Considerations for Eco-LeanSat Satellite Manufacturing and Recycling

Abstract

This research aims to contribute to the development of the Eco-LeanSat concept by focusing on a sustainable approach to satellite manufacturing and the repurposing of remaining satellite capabilities after failure. Despite satellites no longer being suitable for their original purposes, these remaining capabilities can find new applications. The study begins by identifying relevant innovative eco-design applications. Subsequently, it examines sustainability within the satellite lifecycle supply chain, categorizing it into four methods: (1) active debris removal, (2) transport logistics, (3) mission extension, and (4) repair and construction. Aligned with emerging trends in space activities, the study also considers future developments to maximize satellites’ potential to provide new services. Additionally, the research includes a description of a potential lean manufacturing process that encompasses logistic chains to support the development of a more sustainable space economy. Finally, the study concludes with a technological survey tracing the evolution of the development of the SmallSat and CubeSat platforms that identifies relevant innovative designs for a sustainable space environment.

1. Introduction

In the last decades, the space sector market has experienced fast growth. The Space Foundation team [1] estimated that the global space industry, valued at approximately USD 366 billion in 2020, could potentially surpass USD 1 trillion by 2040 [2].

Between 2013 and 2022, a total of 8396 satellites were launched, and in just the first quarter of 2023, 1649 spacecraft were added to this count [3]. The space industry has witnessed profound transformations driven by the emergence of private companies pioneering innovative approaches, including the development of reusable rockets, small satellites, and even space tourism [4]. This transformative movement has been coined “NewSpace” [5], and it is characterized by rapid progress in science and engineering facilitated by technology miniaturization, cost-efficient business models, and rigorous quality control methodologies [6]. These factors have enabled a broader spectrum of participants to engage in the aerospace sector [7,8].

In the past years, the accelerated achievements of NewSpace have contributed to global growth and have led to advancements in the economic, technological, academic, and societal aspects of the space sector [9]. Notably, in the realm of satellite technology, significant strides have been made [10]. Ambitious proposals, driven by the collaborative efforts of the University–Business–States triad, have played a pivotal role in enabling various countries to initiate, develop, and sustain their involvement in the space race [11]. The launch of large constellations, exemplified by recent initiatives such as Starlink, OneWeb, Telesat, Kuiper, and others, serves as compelling evidence of this industry’s substantial growth [12].

As shown in

Table 1. Increase in the percentage of small satellites between the years 2012–2023.

Primary Mission Group	Small SatMarket [13]	Bryce [13]	Seradata [14]	SpaceWorks [15]
Communications	23%	11%	42%	13%
Technology Development	28%	40%	25%	26%
Scientific	23%	8%	12%	13%
Novel Applications/ Other–Unknown	3%	3%	1%	2%
Earth Observation/ Remote Sensing	23%	38%	20%	46%

Source: analysis of SpaceWorks, BryceTech, and Small SatMarket Intelligence databases and Seradata [3,13,14,15].

, the trend of small satellites has witnessed significant growth from 2012 to 2023, and this trend is expected to continue, particularly in the areas of communications, Earth observation (EO), and technology demonstration missions. Table 1 compares the data from four different databases. (As per various sources, the notable variations in percentage values across different databases can be ascribed to the distinct mission classifications in their primary categories. Each database employs different classification parameters, resulting in the consideration of the general mission purpose under the broader category.)The primary missions have been classified into four groups: communications, EO/remote sensing, novel applications/unknown, and scientific and technology development. Almost 60% of the technology demonstration missions have as a primary purpose the maturing of specific components or subsystems, with communications and avionics components being the ones with the largest investments in 2021.

As seen in Figure 1, regarding mass, most nanosatellites (1–10 kg) are commonly used for scientific, EO, and technological applications, while minisatellites (100–500 kg) are more often used for communication purposes, and small satellites (500–1000 kg) are more typically used for navigation missions, despite being less numerous so far. This ranking may change in the future with planned LEO PNT [16] and air traffic control [17] constellations.

Within the mass classification, it is worth mentioning that CubeSats have enabled more participants to actively engage in the space economy. Figure 2 illustrates the number of CubeSats and small satellites launched, along with the mass trends. The most noticeable increases are in the use of nanosatellites, weighing 1–10 kg, and satellites weighing 500–1000 kg.

As the space sector has grown to meet the demands of NewSpace actors, the number of non-functioning space assets in orbit and the risks of debris and space junk collisions between spacecraft have also increased [18,19]. The European Space Agency (ESA) has recorded over 30,000 pieces of space debris [20]. However, it is likely that the number of objects larger than a centimeter exceeds one million. Figure 3a displays numerous unidentified objects (UIs) that were detected and tracked through space surveillance networks [20] between 1960 and 2022, taking into account payload launch traffic within 200 km and a perigee height (hp) of less than or equal to 1750 km. As seen, more than 95% of the satellites launched in 2021 were <1000 kg.

According to the projections of Euroconsult (see Figure 3b), “A total of 3335 smallsats (<10 kg) are expected to launch throughout the next decade, which is more than twice the 1656 launched over 2012–2021” [21].

As of 1 November 2016, ESA’s MASTER model estimated the following numbers of space debris objects in orbit: 34,000 objects larger than 10 cm, 900,000 objects between 1 cm and 10 cm, and 128 million objects from 1 mm to 1 cm [20]. The distribution of objects by size is depicted in Figure 3c, which shows the number of objects larger than each size threshold across all Earth orbits. Figure 3d presents the density profiles at different altitudes in the LEO region for debris sizes of 10 cm and 1 cm, using a logarithmic scale to represent the vast difference in the quantities of these two groups. Figure 3 shows a schematic view of the evolution and projections of space traffic and the orbital debris distribution created using a data analysis and predictive models.

As illustrated in Figure 4, fragmentation events, aside from collisions, currently represent the primary source of space debris. (Note: The end-of-life behavior of space objects can be categorized into seven behavioral classes to illustrate disposal success rates: • NCWO (Not Compliant WithOut attempt): the 25-year rule is not met by the mission orbit and no disposal action has been taken; • NCWFB (Not Compliant With attempt False Before): the 25-year rule is not met by the mission orbit, and a disposal action has been attempted, but it was unsuccessful or insufficient; • NCWTB (Not Compliant With attempt True Before): the 25-year rule was met by the initial mission orbit, and a disposal action has been attempted, but it was unsuccessful or the mission orbit was otherwise altered, and the new orbit is not compliant; • CWFB (Compliant With attempt False Before): the 25-year rule is not met by the mission orbit, but a disposal action has been taken and was successful; • CWTB (Compliant With attempt True Before): the mission orbit met the 25-year guideline, but a disposal action has been taken nonetheless; • CWO (Compliant WithOut attempt): the mission orbit met the 25-year guideline, and no action was taken (nor needed); • CD (Compliant With Direct Re-entry): a controlled re-entry has been performed).

While this percentage is substantial when compared to higher mass categories, it indicates a growing contingent of small payloads that require active means for disposal from the LEO protected region. Conversely, since 2010, the majority of large payloads that reached the end of their missions did so in orbits where they failed to successfully remove themselves. Figure 5 underscores propulsion-related events and anomalies as the categories exhibiting a higher percentage of fragmentation.

Figure 6 highlights propulsion-related events and anomalies as the categories that have exhibited a higher percentage of fragmentation. As can be seen, a significant increase in the number of commercial satellites launched into low Earth orbit (LEO) has taken place in the last few years: the vast majority weighing between 100 and 1000 kg. This trend is also reflected in the growing number of objects in orbit (see Figure 6), which increases the probability of collisions and fragmentation.

Although most constellations have been launched to offer valuable and necessary services, they may create long-term sustainability issues. In the same way, various sustainable strategies have been developed worldwide to address short-, medium-, and long-term solutions aimed at mitigating unsustainable practices in the space sector. One example is the Committee on the Peaceful Uses of Outer Space of the United Nations, which discusses matters related to space and sustainable development [23].

Another example is NASA’s sustainability report and future plans [24], which ensure adherence to the sustainability goals outlined in Executive Order 14057 and NASA policies, with a primary focus on reducing environmental risks and promoting sustainable practices throughout all stages of work [25]. NASA’s sustainability route plan involves the White Sands Test Facility (WSTF), which operates an Environmental Management program. The facility prioritizes waste minimization through the promotion of recycling, reuse, and the Reuse Market Place (ReMaP) software application to divert materials away from landfills. Furthermore, the WSTF is committed to sustainable acquisition, favoring eco-friendly products and services. The Site-wide Sustainability Working Group (S2WG) actively engages employees in initiatives aimed at enhancing water and energy efficiency while meeting mission goals. The facility encourages green projects and relies on S2WG to evaluate funding proposals, encompassing categories like sustainable acquisition, waste reduction, recycling, hazardous waste management, and pollution prevention [26,27]. These endeavors collectively reduce the facility’s environmental impact and cultivate a culture of sustainability [28].

Additionally, numerous other efforts have been undertaken worldwide to address this issue, such as the Cleaning Outer Space Mission through Innovative Capture (COSMIC) from Astroscale Ltd., the UK Space Agency’s mission to remove defunct satellites from low earth orbit [29,30], and the ESA’s Clean Space Initiative [31], which was started in 2012 and considers the environmental impact of the entire lifecycle of space missions [32]. Clean space activities fall into three main areas:

• Eco-design: addressing environmental impacts and fostering green technologies;
• Space debris mitigation: minimizing the production of space debris;
• On-orbit servicing/ADR: removing spacecraft from orbit and demonstrating on-orbit servicing of spacecraft.

Therefore, to ensure the sustainability of future space infrastructure and exploration, it is of paramount importance to consider the removal of human-made space debris through collaborative efforts [33,34]. To contribute to this global initiative, this study aims to formulate a more sustainable approach to space through the Eco-LeanSat concept. This concept entails leveraging satellite characteristics in a sustainable manner to develop reconfigurable satellites during their nominal lifespans and beyond. To achieve this goal, the Eco-LeanSat concept integrates profitability, efficiency, technology, innovation, and environmentally friendly practices through the application of lean methodologies and lean maintenance and repair approaches. The next section examines a sustainability concept approach that incorporates eco-friendly ideas across the supply chain stages for small satellite manufacturing and highlights recent innovative trends. The following section outlines and explains in detail the key characteristics of the evolution of SmallSat capabilities, with thirteen specific mission objectives, including Management and Manufacturing, Disruptive Technologies, Planetary Defense, Sustainable Space, and In-orbit Activities. The final section focuses on the capabilities utilized in SmallSats and CubeSats over their histories. This analysis aims to identify their strengths, key contributors, and significant technological advancements. The purpose of this analysis is to propose optimal features for future Eco-LeanSat designs; it introduces innovative methods to enhance satellite capabilities and manufacturing processes.

2. Sustainability Concept: Implementing a Zero Debris Approach

The proliferation of space debris in Earth’s orbit presents a significant threat to operational satellites and the future of space missions [35,36]. With approximately 128 million debris objects larger than 1 mm, including 34,000 exceeding 10 cm [37], the potential for collisions and their subsequent detrimental effects is a pressing concern [38,39,40].

The exponential growth of space debris, exacerbated by incidents such as the 2009 collision between a defunct Russian satellite and a U.S. satellite, underscores the critical need for proactive measures [41,42]. Operational satellites, fundamental for telecommunications, Earth observation, weather forecast, navigation, and scientific research, face heightened risks from even small debris fragments due to their substantial velocities [43,44,45,46].

2.1. The Zero Debris Approach

Aiming to prevent the cascading effects of debris and ensure the integrity of the space environment, a zero debris approach becomes imperative [47]. In 2022, the ESA proposed eight technical recommendations to attain zero debris by 2030 [31,48]. These recommendations encompass ensuring successful disposal, improving orbital clearance, avoiding collisions, preventing internal break-ups, addressing intentional debris release, assessing on-ground casualty risks, guaranteeing dark and quiet skies, and safeguarding other valuable orbits. Figure 7 provides a summary of each of these pillars.

This section underscores the pressing need to address space debris amidst the burgeoning space industry. The ESA zero debris approach, introduced through the Clean Space Initiative, is a pivotal initiative that aims to eliminate debris production in key orbits by 2030 [31]. The multifaceted strategy involves policy evolution, platform upgrades, removal service development, and improved space operations. With approximately 30,000 pieces of space debris [31,49], effective debris management is paramount to safeguard operational satellites and ensure the uninterrupted provision of essential services. The outlined recommendations for achieving zero debris present a comprehensive framework, including disposal assurance, enhanced orbital clearance, collision avoidance, and the protection of valuable orbits [50,51].

Implementation Strategy

To implement the zero debris approach, the ESA has devised a transversal action plan structured around four main pillars:

• ESA Policy Evolution: Recognizing the need for policy alignment with international guidelines, the ESA is updating its policy to incorporate short-term zero debris recommendations. This stepwise approach aims to achieve zero debris by 2030.
• Upgrade Platforms: Efforts are underway to enhance spacecraft platforms by integrating end-of-life technologies effectively. Key technology developments include deorbiting systems, passivation functions, design for demise, and design for removal.
• Removal Services: ESA is actively developing removal services, including technology development, missions, and standards. Embedding removal interfaces in Copernicus Expansion missions is a crucial step towards fail-safe debris disposal.
• Improved Operations: Enhancing space surveillance and tracking, space traffic coordination, collision avoidance, and close-proximity operations is essential for a successful zero debris implementation. The ESA engages with stakeholders through workshops to enhance satellite operations in these critical areas.

In keeping with this approach, NASA has identified main constraints that prevent speedy action on space sustainability in Earth’s orbit. These challenges include the absence of a unified framework for space sustainability, insufficient metrics and models to support holistic frameworks, uncertainties in the space environment and operations, conflicts between sustainability and other mission interests, and the need for a coordinated global response. To overcome these difficulties, NASA, in its “Space Sustainability Strategy, Volume 1: Earth Orbit, 2024” [52], intends to pursue a series of objectives that build on one another yet can be implemented concurrently.

• Goal 1: Develop a Framework for Assessing Space Sustainability at NASA
  NASA intends to develop an entity relationship model that specifies all quantities of interest and their interdependencies, which will be operationalized through measurements, modeling, and assessments. This approach will aid with defining the existing space traffic and debris environment, developing metrics to assess the long-term viability of orbital activities, and establishing goal values for these metrics. The goals are to define the framework, determine tolerable and desired risk levels, and publicize NASA’s influence on space sustainability on an annual basis.
• Goal 2: Prioritize Efficient Ways to Minimize Uncertainties
  Using the methodology developed, NASA will identify important uncertainties that pose hazards to robotic spacecraft as well as study the effects of orbiting objects on scientific observations and devise cost-effective solutions to eradicate potential negative effects. The goals include identifying opportunities for breakthrough improvements in sensing and anticipating the operating environment, exploring new operational approaches, and developing prioritized approaches to managing current debris challenges.
• Goal 3: Lower Barriers to Space Sustainability Through Technology Development and Transfer
  Based on the lessons gathered from Goal 2, NASA will invest in technologies that promote space sustainability. These expenditures will enhance the capabilities required for long-term operations in Earth’s orbit and will help other U.S. space operators. The goals include investing in early-stage orbital debris management, expanding investments in space situational awareness and traffic coordination, and facilitating debris-related technological demonstrations with possible transition partners.
• Goal 4: Update or Develop Policies to Support Space Sustainability
  NASA will improve space sustainability via policy modifications and advancements. The objectives include updating NASA’s rules and standards based on the results of prior goals, amending debris remediation policies, supporting economic and policy research on space sustainability, and resolving international orbital debris remediation challenges.
• Goal 5: Improve Coordination and Collaboration Outside of NASA
  NASA will continue to lead both domestically and internationally by exploring opportunities for increased information sharing and collaboration with academic institutions, industry, interagency partners, and the global space community. The objectives include collaborating with interagency partners, interacting with space-sustainability-focused communities, exchanging best practices and tools, and capitalizing on technology advancements from the greater space community.
• Goal 6: Enhance NASA’s Internal Organization to Support Space Sustainability
  NASA will establish an entity to supervise the day-to-day coordination and accountability for the agency’s space sustainability activities. This organization will guarantee that NASA meets its sustainability goals, prioritizes related work and funding, and maintains a consistent voice in space sustainability issues.

To achieve space sustainability and ensure a safe orbital environment around the Earth, JAXA, a significant contributor in this arena, is actively engaged in developing technologies to manage space debris and enhance space operation safety. JAXA endeavors to mitigate the risks posed by space debris and foster a sustainable space environment through pioneering research and the creation of groundbreaking technologies. Key objectives for JAXA include advancing rendezvous and capture technologies to handle uncooperative objects and eliminate non-stationary debris from orbit. Additionally, JAXA is at the forefront of low-power electric propulsion technology, enabling smaller spacecraft to effectively remove larger debris from orbit [53].

Facilitating the study of space debris, JAXA’s Space Tracking and Communications Center utilizes radar and optical telescopes to monitor near-Earth space and calculate the orbits of debris. These data enable predictive analyses of debris trajectories, allowing for preemptive measures to safeguard satellites and reduce collision risks [53]. Moreover, JAXA’s Safety and Mission Assurance Department is actively involved in developing international standards to reduce space debris, drawing upon frameworks established by organizations such as the Inter-Agency Space Debris Coordination Committee (IADC) [54] and the International Organization for Standardization (ISO) [55]. Instruments like the Risk Avoidance Assist Tool Based on Debris Collision Probability (RABBIT) [56] enhance satellite safety and contribute to the long-term sustainability of space activities.

Recognizing the paramount importance of space debris mitigation, JAXA has launched the “Commercial Removal of Debris Demonstration (CRD2)” [57] program in collaboration with private business operators. This initiative aims to eliminate large debris from orbit, paving the way for a debris-free and pristine space environment. By fostering new markets and leading international discussions, JAXA endeavors to propel global efforts towards space sustainability and safety.

Involving other relevant institutions of the sector in the implementation of the strategy, the Inter-Agency Space Debris Coordination Committee (IADC) “Report on the Status of the Space Debris Environment 2024” [54] underscores the importance of achieving zero debris in space through sustainable practices. Sustainability in space, defined by the United Nations as serving current requirements without jeopardizing future generations’ demands, requires establishing criteria to measure a viable space environment [54]. While the report acknowledges the effectiveness of space debris mitigation guidelines, it also highlights the need for further adoption and stricter adherence to these measures. Despite efforts to slow the growth of the space debris population, the report warns of a potential doubling of orbital objects within 50 years if current trends persist. Moreover, without additional measures such as active debris removal technology, collisions among existing space debris objects could exacerbate the problem.

Furthermore, prestigious institutions in this field, such as the IAF Space Traffic Management Technical Committee, have conducted research into various aspects of space traffic management (STM) in order to promote safe space exploration and use while minimizing risks to people and property on Earth. This initiative, established through a collaborative effort between the IAA (International Academy of Astronautics), the IISL (International Institute of Space Law), and the IAF (International Astronautical Federation), aims to develop comprehensive recommendations on STM behaviors as well as proposals addressed to decision makers at both national and international levels [58]. The IAF STM TC’s research activities cover a broad spectrum of technical challenges within the STM environment. These include operational coordination services, collision avoidance (both in orbit and during launch and reentry), frequency management and coordination, space hardware disposal, space situational awareness (SSA), space surveillance and tracking (SST), space weather (SWE), space environment management (SEM) for space debris mitigation and remediation, and space operations assurance (SOA), which combines SEM, SSA, and STM. Recent publications from the IAF STM TC emphasize the need for space object monitoring data as the cornerstone of any space traffic management system [58]. The UN Long-Term Sustainability Standards emphasize the need to gather and accurately retain orbital data as well as the development of related technologies in order to support long-term space activities. Ongoing developments in the field include implementing optical surveys in LEO, laser ranging of non-cooperative targets, developing techniques for attitude determination, implementing active LED systems for satellite identification, and addressing challenges in cis-lunar applications [58]. The goal is to identify technological advancements that increase the volume and accuracy of observations, such as ground-based laser tracking to improve ranging accuracy, passive optical systems to supplement radar visibility zones, passive RF systems to improve data timeliness, space-based measurements to collect data on small objects, and attitude motion standards to support emerging missions like active debris removal and on-orbit servicing. These efforts aim to improve STM capabilities and contribute to the long-term management of space activities [58].

Together, these initiatives mark significant progress toward creating a cleaner and safer space environment for future generations, fostering sustained growth in the space industry.

2.2. Towards a Sustainable Orbital Environment

It is crucial to recognize that addressing this challenge necessitates the coordination of various stakeholders to establish standards for maintenance, manufacturing, and space waste management [27,59]. This presents a significant technological challenge, as it involves the advancement of monitoring, synchronization, and comprehensive satellite lifecycle tracking [60]. To tackle these issues, we have introduced a proposal for “Life Extension” into the satellite manufacturing logistics chain, integrating the methods presented as a pivotal and operational part of the satellite’s lifecycle [61,62,63]. This proposal introduces the concept of sustainability as a fundamental addition to the satellite lifecycle supply chain. As depicted in Figure 8, we outline each stage of the satellite supply chain process:

• Manufacturing (comprising components, subsystems, and system integration): It is essential to highlight the advances made in ISO standards for small satellites. The ISO/TC20/SC14 committee [64] began efforts in 2014 to produce standards that define and regulate the use of small satellites, resulting in work item ISO/WD/20991, “Requirements for Small Spacecraft” [65]. This standard seeks to lay the groundwork for the responsible deployment and operation of tiny satellites, with a focus on sustainability and space debris mitigation. In March 2016, the study group presented a report to the IAA, concluding that small satellites should be identified by their design and management philosophy, not their size. The term “lean satellite” has been used to describe satellites that use creative, low-cost ways to enable rapid delivery with small teams. The group developed a scaling system to measure adherence to the lean satellite concept, which was tested on nearly 30 satellites worldwide [66]. In 2019, the Kyushu Institute of Technology (Kyutech), with Japanese government assistance, launched a project to standardize the CubeSat electrical interface [67]. This initiative uses the lean satellite community to get worldwide feedback and build the standard. Activities include editing drafts, coordinating with ISO/TC20/SC14, and organizing international workshops. The standard document, “Space Systems—CubeSat Interface”, is currently being developed. This standard specifies the interface and the documentation required to enable integration and reduce compatibility difficulties, resulting in a substantially shorter process of selecting and testing CubeSat components.
• Operations (involving launch providers and services, space operations, and the ground segment).
• Change of applications.
• Life Extension: A novel proposal that takes into account future missions and emerging technologies. This phase involves evaluating satellite health and operational status in orbit. In case of any failure, two options are considered: (1) in-orbit repair through activities such as rendezvous and docking or (2) active debris removal (ADR), which includes the sustainable waste management techniques mentioned earlier. This proposal also addresses a sustainable final disposal system and the potential for reusing materials for other missions.

The motivation for this sustainable approach arises from identified concerns, where satellites are sometimes decommissioned or abandoned for various reasons, including economic factors, mission completion, or political considerations. In certain instances, new satellites are launched instead of leveraging the capabilities of existing satellites, even in cases of unexpected anomalies. The probability of satellite failure vs. time and subsystem was analyzed in [63]. The probability of failure in the first quarter of its life is three times higher than in the second quarter, and it seven times higher than in the last quarter. Since not all failures in the first quarter are catastrophic and many systems could be repurposed (but are not), this means that their remaining capabilities are underutilized.

In this context, Figure 8 graphically shows the flow to recycle partially failed satellites, or “Zombie Satellites”, to reuse their remaining potential for alternative applications beyond their original design.

Building upon a comprehensive approach that integrates the stages of the satellite logistics chain with the trends examined in the previous sections, Figure 9 provides a summary of the identified emerging trends in space activities, categorized into four primary domains. This figure offers a relational map that encompasses activities on Earth (manufacturing), the ground segment (operations), launch processes, the space segment (mission development), and the interconnections between various activities within each category. During this process, the interconnections between various sustainable methods were identified, offering complementary support to their primary mission objectives. The manufacturing activities on Earth are depicted in yellow, while ground segment activities are marked in red, and launch segment activities are indicated in grey. In the space segment, orange represents activities related to ADR, green represents mission extension activities, and blue represents repair and construction activities. Figure 9 shows the most relevant sustainable proposals, and their interactions with other stages of the chain are highlighted. Based on the analysis conducted in preceding sections, each of these proposals results from the identification of satellite missions that currently possess these capabilities or are expected to acquire them in the near future. Each circle represents the classification within the supply chain stages. Concerning the sustainable supply chain proposal for on-Earth manufacturing, it broadly emphasizes activities that involve: (1) the utilization of new resources, such as recycled materials, miniaturized components, and 3D printing, (2) the implementation of agile methodologies and standardization to reduce costs and time, and (3) the incorporation of new technologies and materials in the manufacturing process. As an example of the incorporation of new sustainable materials, there is a collaboration between NASA and Japan to test an eco-friendly satellite made of wood [68]. This groundbreaking initiative, known as LignoSat, represents a significant step towards eco-friendly space exploration. Unlike traditional satellites built with aluminum, LignoSat will burn completely during re-entry into Earth’s atmosphere, leaving no harmful particles behind [68]. This innovative approach addresses concerns about space debris and contributes to a more sustainable future in orbit. For the launch stage, the selected capability considers the use of platforms that facilitate multiple launches for different orbits, avoiding the generation of multiple launches from the ground, reducing the ecological impact.

In the operations phase, the mission involves integrating various technological developments, which presents multiple challenges related to ground station operations and communications. Achieving this type of operations allows greater versatility and efficiency in communications, data processing, and information gathering, which are fundamental for the success of a satellite mission in a variety of applications: from Earth observation to space exploration and communications. Within the realm of space missions, various proposals have been put forward to enhance the adaptability and efficiency of satellite operations in diverse missions and scenarios. These propositions offer numerous advantages, including:

• Deep Space Exploration: Enabling the execution of missions that venture beyond Earth’s orbit, thereby expanding the scope of space exploration capabilities.
• Autonomous Removal and Earth Re-Entry: Simplifying the process of retiring satellites at the end of their operational life, either through mechanical structures or autonomous means, thereby contributing to the reduction of space debris and facilitating payload recovery.
• Autonomous Rendezvous Operations: Equipping satellites with the capability to autonomously approach and engage with cooperative or non-cooperative objects in the vastness of space.
• Conducting Experiments: Enabling the broadening of our knowledge and the enhancement of our capabilities across various scientific domains.
• Multi-Satellite Missions: This encompasses the deployment of satellite constellations and fractionated missions [69] that provide extended coverage and increased operational redundancy.
• In-Orbit Manufacturing and Assembly: The ability to craft components or conduct assembly in the space environment, thereby reducing reliance on Earth-based resources and adapting to unforeseen circumstances.
• Satellite Recycling: The potential to recover and repurpose satellites, thereby contributing to cost reduction and the mitigation of space debris concerns.
• Secure Cryptographic Keys: Leveraging the unique quantum properties of light and onboard intelligence to secure space-based communications.
• Active Maneuvers: Empowering satellites to execute more efficient attitude control and optimize their positioning with regard to factors such as solar exposure, darkness, Earth orientation, and more.
• On-Orbit Operations: The capacity to carry out updates to software and hardware while in orbit, ultimately enhancing satellite flexibility and longevity. OSS facilitates the extension of satellite lifespans by allowing for inspection, refueling, maintenance, and upgrades, which improves the performance and return on investment (ROI). It promotes space sustainability by reusing, refurbishing, and recycling materials while also reducing orbital congestion through deorbiting technology and prolonged satellite lifetimes: hence, reducing the demand for new launches. However, current OSS technologies face several challenges, including the lack of a successful demonstration track record, an insufficient legal framework to address liability issues, the cost-effectiveness of replacing satellites versus servicing them, and the need for industry consensus on interoperability standards. Furthermore, the dual-use nature of ISAM technology raises concerns about anti-satellite capabilities, which could jeopardize space sustainability initiatives [70].

These capabilities play a pivotal role in enhancing the versatility and efficiency of satellite missions while simultaneously addressing the challenges within the realms of space exploration, space debris management, and the security of space-based communication.

2.3. Efforts towards a Sustainable Supply Chain

Collective efforts by various national and international organizations actively contribute to the sustainability of satellite technology and supply chains [71,72]. This section details key trends in the supply chain phases, encompassing satellite reliability and maintainability, with a strong focus on eco-efficient methodologies and materials. While challenges persist in the manufacturing phase, this section emphasizes the necessity to adopt a holistic approach for materials assessments and environmentally responsible disposal practices. In a world with finite resources, it underscores the growing recognition of environmental sustainability within satellite supply chains, urges efficient resource management throughout the satellite mission lifecycle, and facilitates the transition towards a fully sustainable satellite supply chain [73,74].

2.3.1. Highlighting Progress in Applying This Concept

In relation to the management and operations within a satellite supply chain, NASA has taken the lead in advancing a reliability and maintainability (R&M) program to ensure that systems within NASA’s spaceflight programs and projects perform as intended throughout their lifecycles, thus achieving mission objectives related to safety, mission success, and sustainability [75,76]. The program emphasizes innovation and continuous enhancement to meet the ever-evolving requirements of NASA’s programs and projects [77,78].

Parallel initiatives exist among major space agencies across the globe, reflecting a shared commitment to enhance the reliability and maintainability of space missions. The European Space Agency (ESA) places a significant emphasis on these critical engineering aspects within their space missions. The ESA’s collaborations with industry partners revolve around the development of advanced technologies and materials specifically engineered to withstand the harsh environmental conditions of space while adhering to stringent environmental impact mitigation strategies [79,80].

Similarly, JAXA proactively prioritizes the reliability and maintainability of its satellite missions, adhering to an engineering approach and materials selection that are not only instrumental to ensure mission success but also align with their overarching commitment to environmental responsibility [79,81].

These endeavors within space agencies underscore the paramount importance of engineering excellence in space missions with a concurrent focus on environmental stewardship.

One of the projects contributing to that is the SCHUMANN project [62]. Co-funded by EC (DG DEFIS) within the Horizon Europe framework and coordinated by Space Applications Services (Belgium), it aims to strengthen Europe’s leadership in NewSpace and in-orbit servicing, assembly and manufacturing (ISAM) applications [82].

NewSpace is the new “space industry and applications” paradigm that was established a few years ago and which is progressively evolving. Applications such as satellite life extension, refueling, in-space assembly, in-space reconfigurable mechanisms, and in-space recycling will offer substantial revenue opportunities exceeding EUR 10 billion by 2030 [83].

SCHUMANN is looking to simplify the integration of modular spacecraft elements for satellite manufacturers as well as to drive reductions in the costs of doing so. The first path involves the design and maturation of a modular refueling module (MRM) to give satellites extra life, while the other path, called the satellite construction kit (SCK), will see the creation of a software toolkit that will help developers of functional satellite modules (FSM) demonstrate compliance for the necessary subparts [83].

In addition, numerous national and international organizations are actively involved in advancing satellite technology and supply chain sustainability [44,71]. Their collective efforts contribute to the ongoing development of reliable, maintainable, and environmentally conscious satellite systems that benefit scientific research, Earth observation, and space exploration [72,84,85]. For manufacturing processes and associated activities in orbit to be sustainable, it is crucial to evaluate the properties and behavior of components or materials in the space environment [86,87]. These efforts collectively promote the responsible use of space resources and foster collaboration on a global scale to address the challenges of satellite supply chain sustainability [88,89].

Table A4. Supply Chain Stages Trends for satellite development.

Supply Chain Stage	Category	Trend	Description	Characteristics	Company/ Institution
Manufacturing	Methodologies	Agile and Lean methodologies- Six Sigma	Applications of methods for low-cost, fast delivery, and waste minimization	• Small size	Kysushu Institute of Technology
				• Use of non-space-qualified COTS units
		Vertical Integration in Satellite Manufacturing		• Efficient manufacturing practices.	SpaceWorks
				• Development and production costs of the constellation, amortized across the number of operational satellites.
	New engineering methods and technologies	4.0 Industry	Low-cost, mass-production, data-driven, reduce lead time business model	• Reusable Launchers	Capgemini-engineering
				• LEO satellites constellations
				• Digital transformation
				• Agility methods/ Flexibility
				• Cloud computing
				• Digitalize the manufacturing processes
				• 3D- Printing
				• Digital Twins
				• Artificial Intelligent
				• IOT & connectivity
				• Virtual & augmented reality
				• AIT expertise & tools
				• Product Lifecycle Management (PLM)
				• Integration between design and manufacturing
	Materials	New and current	Flexible carbon-fiber	Tailor-made composites for tougher space structures	ESA
	Space infrastructure	Robots	Self-assemble test	Small cubes with no external moving parts can self-propel, stack, and form various shapes in experiments [136]	Massachusetts Institute of Technology (MIT)
			Robotic arm to build satellites in space	• Length of 11.3 meters, the symmetrical, two-handed intelligent robot arm	Airbus
				• Control computer in the middle of the arm give the robot arm its versatility.
		3D- Printing	Portable Onboard Printer 3D	Producing a system of automated additive manufacturing aboard the International Space Station	Capgemini-engineering
Launch Services	In-space transportation services	ION Satellite Carrier deployer	Satellite transports across orbits into its final operational slot.	• Onboard software to process incoming commands, perform mission operations, process raw data, and downlink information	D-Orbit
				• Multiple form factor support: capacity (a 64 1U and multiple combinations of CubeSats, or microsatellites up to 160 kg.
		DPODs and DCUBEs dispensers		• Ability to perform orbital maneuvers:
				• Precise deployment
		Dispensers- RUAG Space	Satellite transports	• 1.7-meter central cylinder structure and a height of 5.5 meters.	Airbus
				• Automated Potting Process
				• Multi-layer thermal insulation
	Orbital Transfer Vehicles	Sherpa Program	Transportation for LEO, trans-lunar and low-lunar orbits, or beyond to GEO	• Executing multiple deployments,	Spaceflight
				• Providing independent and detailed deployment telemetry, and flexible interfaces.
				• Propulsion technology
	Separation System	CarboNIX	Synchronous spring pusher system deploys satellites smoothly and evenly	• Scalable separation system that is available in sizes of 8″, 15″ and 24″ diameter for microsatellites weighting from 10 up to 500 kg.	Exolaunch
				• Reduce the risk of damaging sensitive satellites optical payloads and electronic components
	Cluster Capabilities	EXOports	Multiport Adapter	• Cluster to be built on a single 15” or 24” ESPA or SpaceX Dispenser Ring port.	Exolaunch
Satellite operation/ Sustainability stage	Spacecraft Docking and Connection Device	FuseBlox™	Soft and hard capture with near-zero momentum transfer and provide high-reliability electrical power and data connectivity	• Self-aligning grapple technique accommodates small spacecraft rendezvous misalignments while device symmetry enables four secure mated configurations	SpaceWorks
				• Modular Capacity for expanding in-space infrastructure
				• Supports gigabit ethernet and MIL-STD-1553 data connections
				• Enabling architectures for space-based solar power
				• In-space assembly and manufacturing
		Docking Plate	In-orbit servicing, refueling, refurbishments and relocation.	• Demonstrate proactive responsible space practice and space sustainability	Astroscale
				• Lightweight, compact and minimally intrusive.
	Refueling Satellites in Space	Refueling technology.	Gas Stations in Space	• End-to-end refueling service using its Rapidly Attachable Fluid Transfer Interface (RAFTI)	Lockheed Martin
				• Drop-in replacement for existing satellite fill-and-drain valves
Life extension/ Sustainability stage	Recycling space debris into raw materials	Refine metal space debris	Space applications with recycling materials	• Provider of refined material for the construction of large orbital stations, the retrofit and repair of satellites, and assembly of reusable spacecraft.	CisLunar Industries (CLI); Space Foundry Airbus and the European Commission
				• Reusable space tugs will deliver large debris items, to be processed and refined to customer specifications.
	Active Debris Removal (ADR)/	Self-Removal	Self-Removal of Spacecraft (TeSeR) program	• Development of a prototype of a “cost-efficient but highly reliable” removal module.
				• Three different removal technologies: solid propulsion, drag augmentation systems and electrodynamic tether.

(Appendix A) illustrates the most notable trends observed in the various stages of the supply chain for satellite development.

In the Manufacturing stage, there are proposals [32] that encompass new methodologies for cost-efficiency, rapid delivery, and waste reduction. This includes the incorporation of new engineering methods and technologies like Industry 4.0 as well as space infrastructures for robotic in-orbit assembly and component manufacturing [90,91]. Moving to the Launch stage, we find developments related to orbital transfer vehicles, in-space transportation services [92], separation systems, and cluster capabilities [93]. In the Satellite Operation stage, with a focus on sustainability, there are advancements in spacecraft docking and connection devices [94,95] as well as for the refueling of satellites in space [96,97]. Finally, in the Satellite Life Extension proposal stage, we consider developments in recycling space debris into raw materials and active debris removal (ADR) [98,99,100].

2.3.2. Challenges

One segment that has presented significant challenges within the supply chain is the manufacturing stage processes. Efforts to enhance reliability during this stage have led to advances in the performance of new materials, technologies, software, and more for space applications [101]. Consequently, there has been a concerted effort to improve the performance of satellite subsystems and extend their missions [102]. Over the years, the satellite industry has witnessed a significant evolution in its supply chain dynamics. Earlier, the supply chain for satellite missions was primarily characterized by long lead times, high costs, and limited suppliers [6,72]. However, with technological advances and the emergence of a more competitive space industry, supply chain management for satellites has evolved. This evolution includes streamlined manufacturing processes, improved component standardization, and the diversification of suppliers, resulting in reduced costs and increased accessibility to satellite technology [103].

In a sustainable approach, the evaluation of these new materials should not only encompass their performance within the satellite structure, but it should also consider their impact when used in space (e.g., for repairs or in-orbit manufacturing) or upon re-entry into the Earth’s atmosphere. Additionally, the final disposal of these materials at the end of their useful life should be considered, including options for recycling or utilization in other processes [104,105]. This holistic approach to supply chain management in the satellite industry reflects the growing awareness of environmental sustainability and the need to manage resources efficiently throughout the entire lifecycle of satellite missions [106,107].

The primary hurdles for future CubeSat and small satellite technologies include coordination, data processing, propulsion, de-orbiting devices, and large deployable structures. Coordinating huge constellations of small satellites poses significant challenges, which can be solved via inter-satellite link (ISL) communications and satellite docking programs. Furthermore, the use of artificial intelligence (AI) will allow for autonomous diagnostics, on-board data processing, and constellation management, all of which improve operating efficiency. Increasing data processing and transmission capabilities necessitates the use of modern communication technologies such as Ku-band and Ka-band transmitters or laser communication, but with careful power management concerns. Furthermore, the utilization of propulsion systems, particularly those based on electricity, chemicals, or water, allows for controlled satellite movement and orbital modifications. Improvements in active and passive de-orbiting systems, such as electric and chemical propulsion, as well as passive systems like air drag augmentation devices (DADs), help to reduce the risks associated with space debris. Additionally, novel solutions such as origami-inspired antenna designs improve space utilization and communication capabilities. Finally, CubeSats are increasingly being used for space exploration missions, which provide chances for scientific inquiry and technology development. However, the proliferation of CubeSats requires the development of new laws to assure safe and interference-free operation. To overcome these obstacles and achieve long-term space exploration goals, stakeholders such as governments, industry, and academia must work together.

2.4. What Actions Can Be Taken Today with Existing Space Debris?

The increasing deployment of satellites is essential to meet diverse user needs in daily life. However, a substantial number of launched satellites, despite the increasing volume, do not operate throughout their expected lifespans. This is often due to various reasons, such as economic constraints, mission completion, or political considerations [108,109]. In certain instances, new satellites are launched to replace those experiencing unexpected anomalies rather than leveraging their residual capabilities.

Observations indicate that failed satellites are often decommissioned, moved to graveyard orbits, or allowed to drift without re-evaluating the anomaly for potential alternative uses. However, failed satellites experiencing non-fatal anomalies can be repurposed depending on their remaining capabilities [63]. For instance, data link anomalies may allow the satellite to support low-rate applications like IoT, environmental monitoring, asset tracking, etc.

For current space debris, there are studies considering potential in-orbit recycling: involving an analysis of operable capabilities that could be somehow reused for other purposes. These satellites, known as zombie satellites, require a detailed examination of each satellite, subsystem, and mission [63]. However, this proposal is accompanied by various challenges that are still being addressed globally.

Prospective initiatives ought to focus on providing comprehensive anomaly descriptions to better grasp their implications on satellite architectures. Overcoming the challenges associated with reviving failed satellites demands addressing technological, regulatory, liability, legal, and ownership barriers. The design and technology of forthcoming satellites should prioritize flexibility in both hardware and software architectures [110,111]. Furthermore, it is crucial to heighten awareness within the industry about the economic and environmental advantages of repurposing satellites, encompassing the reduction of orbital congestion, the minimization of unnecessary launches, the mitigation of space debris, and the alleviation of ecological impacts on the planet [112]. Notably, the Eco-LeanSat proposal lays the groundwork for a potential future satellite infrastructure, facilitating the execution of reuse operations for both hardware and software. Considering the previous study of sustainable proposals for eco-design and their application in the supply chain, and with a view towards applying them to future satellites, the following chapter conducts a technology survey. This survey traces the evolution of SmallSat and CubeSat platform developments, identifying relevant innovative designs and highlighting applications oriented towards sustainable space practices.

3. Eco-LeanSat Proposal

A proposal to develop satellites that can incorporate a sustainable approach from the manufacturing process first involves the identification of the most disruptive capabilities of small satellites so that they can be implemented in an Eco-LeanSat.

3.1. Preliminary Context of SmallSat Capability Evolution

Since the launch of Sputnik in 1957, continuous efforts have been dedicated to develop more capable satellites in smaller form factors. Figure 10 illustrates select examples of successful missions and space probes over time before 1999. A total of 28 missions have been selected, and among them, those considered by the authors as milestones have made pioneering contributions to specific aspects of satellite development, thus representing significant advancements in the field.

In 1999 the CubeSat concept was introduced by Professors Robert Twiggs and Jordi Puig-Suari [114]. It was originally a new educational tool proposed for “low-cost” satellite design, but later on, CubeSat become a “de facto” standard that opened new technological and scientific venues leading to the development of new satellite capabilities. In the following subsections, four main “periods” in the development of satellite capabilities since 1999 have been identified, and they are graphically summarized in Figure 11. A total of 28 missions, either fully successful or partially successful, have been meticulously selected and analyzed, and those that were milestones because of their innovative processes are included.

3.2. First Period: Early Development of Small Satellites and CubeSats (1999–2003)

Thanks to the development of the CubeSat concept, new technologies were tested, avoiding the economic risk of tests using large satellites. In addition, among other significant innovations originated by this concept, new structural and mission design models were introduced, new proposals for launches and operations of space systems were planned, and new payloads for scientific and academic experiments were designed.

Gradually, new players began to promote the commercialization of these structures to turn them into potentially profitable products [115,116].

Based on the authors’ opinion, some of the most important milestones of this period are summarized below.

(a)

Hyperion, the first in-orbit hyperspectral imager, was launched in 2000 on board the LEO-1 spacecraft [117]. It had a spectral resolution of 10 nm in both the visible near-infrared (VNIR) and short-wave infrared (SWIR) regions [118].

(b)

In 2002, JAXA launched three satellites, two of which were small. The first of these, TSUBASA (MDS-1), was designed to verify the necessary technologies in space based on three keywords: faster operation, lower cost, and increased reliability [119]. The satellite demonstrated primary data collection, allowing scientists to experiment before implementing the payloads in larger satellites. Additionally, the satellite contained complex parts developed by the industry to assess their performance and produce smaller and lighter components at a lower cost. The second satellite was a small research satellite that established small satellite spin bus technologies and offered opportunities for in-space verification [119]. This satellite was unique in the sense that it was “handmade” and was fabricated mainly by young JAXA engineers. The project served as a test case to produce small satellites more efficiently and at a reduced cost.

Israel has also explored other types of military small satellites. The Ofeq 5 series was part of the Israeli spy optical surveillance satellites [120]. The first launch of this CubeSat was made on June 20, 2003 [121], in Plesetsk, Russia, on a Eurockot rocket using Russia’s Multiple Mission Orbit Service. The Ofeq series have retrograde orbits due to Israel’s Mediterranean launch path, and they are an upgraded version of the initial Ofeq reconnaissance satellites, which were similar to EROS-A.

A group of CubeSats was launched into a sun-synchronous orbit, which included the Danish AAU CubeSat and DTUSat, Japanese XI-IV and CUTE-1, Canadian Can X-1, and Quakesat. The latter used a series of low-frequency ground sensors designed to detect the energy emitted in the LF part of the electromagnetic spectrum before an earthquake occurs [122].

3.3. Second Period: Technology Demonstrations (2004–2009)

This period begins with the second generation of the GLONASS constellation and ends with the beginning of the development and launch of the European Galileo satellite constellation.

In the authors’ opinion, some of the most important milestones of this period are:

(a)

In 2005, Japan launched an optical in-orbit communications engineering test satellite called “KIRARI”. This satellite had a large-aperture telescope, a high-power semiconductor laser, and highly sensitive signal detectors. It allowed the testing of operations such as beam acquisition to capture an incoming laser beam, beam tracking to detect and control the angle of the incoming laser, and beam pointing to transmit a laser beam accurately in the right direction [123,124].

(b)

In 2006, NASA launched Genesat 1: a technology demonstration and biological experimentation mission. The satellite integrated a miniaturized life support system and a nutrient delivery system for a colony of Escherichia coli bacteria in order to track genetic changes under space conditions [125].

(c)

The Constellation of Small Satellites for Mediterranean Basin Observation (COSMO-SkyMed) was launched in 2007. Each satellite of the constellation is equipped with a SAR-2000: a multi-mode SAR (synthetic aperture radar) instrument with programmable swath size, spatial resolution, and polarization configurations. The SAR transmitter/receiver system operates with an electrically steerable multibeam antenna [126].

Between 2008 and 2009, the first systematic CubeSat-based research program, the Colony-1 CubeSats, were launched by the U.S. National Science Foundation’s Geosciences Division, AS&T (Advanced Systems and Technology Directorate) of the National Reconnaissance Office (NRO). The Weather Colony Program demonstrated the feasibility of scientific payloads in CubeSats, such as small, low-power sensors to measure space weather, monitor solar radiation, measure Earth’s magnetic field, etc. This project also accelerated aspects of technology testing and capabilities with reduced costs and tighter schedules than traditional large satellites [127,128]. The results in

Table 2. Evolution of EO technologies for CubeSat-based missions (from [129], p. 12).

Technology	2012 Technology Review [130]	2017 Technology Review [131]	Justification
Atmospheric chemistry instruments	Problematic	Feasible	PICASSO, IR sounders
Atmospheric temperature and humidity sounders	Feasible	Feasible	—
Cloud profile and rain radars	Unfeasible	Feasible	JPL RainCube demo
Earth radiation budget radiometers	Feasible	Feasible	SERB, RAVAN
Gravity instruments	Feasible	Feasible	No demo mission
Hi-res optical imagers	Unfeasible	Feasible	Planet Labs
Imaging microwave radars	Unfeasible	Problematic	Ka-Band 12 U design
Imaging multispectral radiometers (Vis/IR)	Problematic	Feasible	AstroDigital
Imaging multispectral radiometers ($\mathsf{\mu }$W)	Problematic	Feasible	TEMPEST
Lidars	Unfeasible	Problematic	DIAL laser occultation
Lightning imagers	Feasible	Feasible	—
Magnetic field	Feasible	Feasible	InSPIRE
Multiple direction/ polarization radiometers	Problematic	Feasible	HARP Polarimeter
Ocean color instruments	Feasible	Feasible	SeaHawk
Precision orbit	Feasible	Feasible	CanX-4 and CanX-5
Radar altimeters	Unfeasible	Feasible	Bistatic LEO-GEO/ MEO
Scatterometers	Unfeasible	Feasible	CYGNSS (GNSS-R)

(from [129], p. 12) summarize the evolution of payload development.

In Europe, the construction and launch of the Galileo constellation began. The mass of these satellites is approximately 700 kg [132].

3.4. Third Period: Technology Demonstrations (2010–2014)

In this period, CubeSat platforms mature and, despite most of the launches still being carried out by academia, numerous techdemos see the light of day. Some of the most important milestones are listed below.

(a)

In 2011, ExactEarth acquired small satellites for commercial maritime applications [15]. SmallSat launches were primarily augmented with data transmission capabilities for communication or imaging applications [114]. Another significant milestone was the development of the international CubeSat-based QB50 mission led by the Von Karman Institute for Fluid Dynamics. QB50 consisted of a network of 50 CubeSats built by teams of students from universities around the world to conduct multipoint in situ measurements of the lower thermosphere [133,134].

(b)

In 2013, NanoRacks became the first commercial operator to launch from the International Space Station (ISS) [15]. In the same year, the Cosmogia company (now Planet Labs launched its first Dove pathfinder satellite (Dove 1) [15]. (Planet owns and operates a constellation of more than five hundred 3U imaging satellites with a spacial resolution of ~5 m [135,136].) Its goal was to show the performance of a small camera payload and demonstrate the ability to design, produce, and operate satellites in short times and at a low-cost using commercial off-the-shelf components [137]. Planet’s primary Earth observation payload is an electro-optical imaging system operating in the visible band and with a ground resolution of approximately 5 m. Its secondary payload is a low-resolution IR imaging system with a ground resolution of approximately 1 km [138].

(c)

A year later, Planet launched 93 additional satellites into orbit. Nearly simultaneously, Spire Global, a space-to-cloud data and analytics company, successfully deployed its first satellite model: the Lemur 1. This satellite was equipped with the STRATOS payload, which collects GNSS-RO (radio occultation) for various Earth observation applications, including climate and space weather research by Spire [15]. The Argentinean SAOCOM 1A (Satélite Argentino de Observación Con Microondas) constellation comprises two L-band synthetic aperture radar (SAR) satellites and offer crucial data for applications like measuring Earth surface changes, crop management, and flood monitoring [139,140].

3.5. Fourth Period: Novel Applications (2015–Present)

In this period, the number of CubeSats increased exponentially. Commercial companies entered into the marked, either providing services, satellite subsystems, or fully integrated platforms. Some of the most important milestones are listed below.

3.5.1. CubeSats: Global Advances and Scientific Applications from 2015 to 2018

(a)

In 2015, China launched the first quantum communications satellite together with ³Cat-2—the first CubeSat launched by the Universitat Politècnica de Catalunya (UPC), Spain. It was equipped with a GNSS-reflectometry payload [114].

(b)

Orbital ATK (now Northrop Grumman) successfully launched its first ISS resupply mission with the Cygnus spacecraft; it carried more than 20 satellites [15]. From 1999 to 2015, around 80% of all CubeSats were developed in the U.S. Japan launched 18 CubeSats, Germany launched 10, Denmark launched 9, and Italy, the UK, and South Korea launched 4 each. Since then, over 30 other countries have launched at least one CubeSat.

(c)

In 2016, the International Space Science Institute in Bern, Switzerland, organized a forum to study the evolution of CubeSats as enabling technology platforms. These institutions identified developments aimed at areas such as space physics, focusing on issues like radiation belt variability and complementing missions such as the Van Allen probes [141]. Additionally, in the fields of planetary sciences and astrophysics, research focused on describing new measurement techniques enabled by CubeSats.

In this period, the CubeSat concept became a powerful tool. Because they can be launched easily, the revisit time can be reduced, and also, they can address specific scientific questions for which traditional satellite approaches are not suitable. In this period, space exploration was more accessible, and scientific and technological developments were encouraged in order to innovate satellite systems and their payloads. According to a study conducted by the U.S. National Academies of Sciences, Engineering, and Medicine, the most significant improvement during this time was the precise control of the CubeSat’s attitude [114]. Progress and developments in other satellite subsystems, such as solar panels, organic solar cells, hydrogen cells, and power sources [142], as well as the optimization of communication systems with larger data transmission rates [114], including deployable antennas, optical communications, and inter-satellite links, are noteworthy.

(d)

Similarly, between 2016 and 2018, important research efforts were directed towards propulsion technologies for small satellites, enabling them to achieve new scientifically valuable orbits for specialized experiments or to control their trajectories with other platforms. Plasma thrusters and ion engines designed for CubeSat-type structures have been developed [143,144], and today, thanks to these advances, notable projects like CAPSTONE (Cis-lunar Autonomous Positioning System Technology Operations and Navigation Experiment) [145] have successfully placed spacecraft in a near-rectilinear halo orbit (NRHO).

Recent advances in satellite technology have prompted state policies owing to the high capacities developed in satellites. An example was the announcement on 21 October 2016 by the White House (U.S.) of the “Harnessing the Small Satellite Revolution” initiative, building on a growing wave of private sector interest in miniaturized spacecraft for applications ranging from remote sensing and communications to satellite inspection and repair. One of the opportunities that was raised was NASA’s purchase of up to USD 30 million of Earth observation data collected by small satellites and the creation of a new Small Spacecraft Virtual Institute based at the Ames Research Center in Silicon Valley and with the aim of documenting best practices, lessons learned, and standards for all phases of small-satellite development [146].

In the same year, China launched the satellite Tianyuan-1: the country’s first in-space refueling system for orbital satellites [147]. Aolong-1 was the world’s first active orbital debris removal experimental project. It was equipped with a robotic arm to simulate the grabbing of abandoned satellites and other large pieces of debris in space and could take them to the atmosphere for burning during reentry [148].

(e)

In 2017, OneWeb inaugurated a modern satellite production facility, which increased the number of small satellite launches [15], and the Polar Satellite Launch Vehicle (PSLV)-37 program of the Indian Space Research Organization (ISRO) deployed a record number of 104 satellites in a single launch [15]. One year later, NASA’s Jet Propulsion Laboratory launched Mars Cube One (MarCO) [149]: a technology demonstration mission consisting of two 6U CubeSats, MARCO-A and MARCO-B, which were the first over-interplanetary CubeSats and acted as a data relay for the Mars InSight lander for a short period of time. The MarCO pair conducted communications and navigation while flying independently of the planet Mars [149].

(f)

In the same year, Sun-Synchronous Orbit (SSO)-A from SpaceFlight Industries carried 64 satellites from 17 countries into orbit [150].

Regarding the development of new payloads, in 2017, the first Finnish satellite was launched, Aalto-1, with the Aalto Spectral Imager (AaSI): the first hyperspectral imaging system compatible with nanosatellites and the radiation monitor (RADMON) and electrostatic plasma brake (EPB) missions. The latter was a novel deorbiting technology that employed Coulomb drag between the ionospheric plasma and a long, charged tether [151,152,153]. A similar experiment was conducted on board ESTCube-1 [154,155].

(g)

In 2018, HyperScout-1 became the first hyperspectral imager for nanosatellites [156]. It is also relevant to mention the TUBSAT-1 mission (1991), which was one of the pioneering satellites for multi-purpose imagery (ocean and land) through the use of high-resolution optical imagers, data collection, and hyperspectral imagers [157].

3.5.2. Satellite Technology Breakthroughs: 2019–2020 Achievements and Developments

(h)

In 2019, Capella Space launched the world’s first sub-50 kg SAR satellite (Denali) for a technology demonstration mission. Later versions were designed to operate a constellation of 36 satellites. These satellites were equipped with an X-band SAR boasting a 0.5 m resolution, enabling all-weather imaging through an antenna spanning nearly 100 square feet. These satellites offer hourly images of any location on the surface of the Earth [158].

AstroDigital launched the world’s first 16U CubeSat (Palisade) in the same year. It was a technology demonstration satellite with an onboard propulsion system [159]. Also, India developed the Cartosat-3 satellite, which provides very-high-resolution panchromatic imagery with a resolution of 0.28 m and multispectral imagery in four spectral bands with a spatial resolution of 1.12 m; it has a nominal swath of ~17 km.

Many new technologies have been developed, such as highly agile structural platforms, payload platforms, higher-rate data handling and transmission systems, advanced onboard computers, new power electronics, and dual-gimbal antennas [159,160].

(i)

In 2020, the UPC Federated Satellite System (FSSCat) mission marked a significant milestone by employing AI for the first time for cloud detection. FSSCat consisted of two 6-unit CubeSats: one of them was equipped with UPC’s Flexible Microwave Payload-2 (FMPL-2), featuring an L-band microwave radiometer and a GNSS reflectometer implemented in a Zynq—7045 FPGA for sea ice and soil moisture monitoring. Additionally, the second CubeSat included Cosine’s HyperScout-2 visible + near-infrared + thermal infrared hyperspectral imager and included the PhiSat-1 AI board in a Movidius processor. Notably, FSSCat was the first CubeSat-based mission that contributed to the Copernicus program [161]. The application of AI in CubeSat missions has revolutionized the efficiency and accuracy of data processing. By employing AI algorithms, CubeSats can conduct real-time data analysis, make autonomous decisions, and optimize satellite operations, leading to enhanced mission performance and reduced operational costs. For the FSSCat mission, AI was utilized to select data for download based on cloud coverage, optimizing data transmission. This integration of AI in CubeSats exemplifies how advanced technologies enhance the efficiency and effectiveness of space exploration endeavors.

3.5.3. Space Technology Innovations: Advancements and Sustainability

Governments, universities, and commercial companies in the space sector have been adopting new and innovative solutions to the manufacturing processes of small structures and have been proposing new payloads. For instance, Fleet Space Technologies, an Australian manufacturer, developed the first 3D-printed satellite, Alpha CubeSat, and the first 3D-printed rocket, Terran 1, which was launched on 24 March 2023 by the American company Relativity Space. The use of 3D printing enables the production of custom satellites with a general structure and system parts at a much lower cost than conventional satellites.

Significant innovations encompass optical and laser technology and AI; these play a crucial role in Earth observation and environmental monitoring. They improve data precision for climate monitoring, disaster detection, and resource management. These advancements also strengthen satellite communications, facilitating high-speed, low-latency transmissions, which are essential for services like Starlink’s efficient, high-performance satellite network. Currently, Starlink’s satellite communications constellation comprises over 4000 satellites in orbit. Yet in the near future, companies such as OneWeb and Telesat plan to establish smaller constellations. Tech giants like Amazon and Samsung have also announced intentions to deploy their own constellations, consisting of 3236 and 4600 broadband satellites, respectively [162].

Moreover, artificial intelligence enhances accuracy and responsiveness in satellite navigation, benefiting both civilian and military navigation. In the field of science and space exploration, advanced optical technologies enable detailed observations of celestial objects and planets, which is essential for space research and exploration. They are also applied for security and defense, precision agriculture, and the exploration of natural resources. These innovations drive satellite efficiency and precision, making a significant impact on society and industry [163,164].

Another field of sustainable technological development has been the removal of space debris in orbit. In October 2021, China launched the debris mitigation technology satellite Shijian-21, which uses its propulsion to circularize its orbit more than 22,000 miles over the equator. Since then, it has been conducting rendezvous and proximity operations (RPO) with other objects [165].

Furthermore, the Finnish company ICEYE has been a pioneer in the miniaturizing of SAR and deploying it on microsatellites. These satellites have demonstrated their value not only for ice detection but also for a wide range of valuable applications [166,167,168].

3.5.4. CubeSats and Beyond: Advances and Future Initiatives

South Africa has achieved significant progress in camera technology through the EOS-SAT satellite, which was tailor-made for the agricultural sector. This satellite boasts an impressive 40 km swath width and includes 11 band channels, with ground resolutions ranging from 1.5 to 2.8 m [169,170]. Another noteworthy camera developed in South Africa is the Simera Sense xScape100, which offers multispectral and hyperspectral options [171].

In addition, in the last few years, university projects have been essential to this accelerated progress. One of them is the WormSail satellite: developed via cooperation between the University of Nottingham and the University of Brasilia. The satellite is expected to be launched in 2023 or 2024; if successful, it could be the world’s first multicellular organism on a CubeSat flight [172]. Other mission objectives include the in-orbit demonstration of a flight software algorithm to perform packet routing, a set of observation subsystems to collect images and data from on-board sensors, and a new attitude maneuvering subsystem that includes a three-axis magnetorquer and passive deorbiting mechanism based on origami-type structures and atomic oxygen corrosion [173].

To summarize, until 2013, CubeSats were a small field dominated by academic and university projects. After 2013, mostly due to Planet and Spire Global constellations, most CubeSats shifted to the commercial sector. As of 2012, only 72 CubeSats were in orbit, and as of May 2023, more than 2100 CubeSats have been successfully deployed into orbit. Today, the communications field intends to improve the performance of 5G ecosystems and beyond through non-terrestrial networks (NTNs) based on satellite constellations [174]. Furthermore, there is a trend to develop scientific experiments and create space architectures that use reusable vehicles to access space and return to Earth, such as the Space Rider, which has been conceived to provide a space laboratory for payloads to operate in orbit for a variety of applications [175].

Since the introduction of the CubeSat standard, over the last two decades, technology has achieved a high level of maturity, particularly for generating high power using large, deployable solar panels, which is vital for Earth observation and communication missions. However, notable challenges persist, including the need for larger deployable structures to support advanced antennas, high-precision attitude control systems, enhanced RF inter-satellite links, flexible systems for managing diverse payloads, integration of artificial intelligence for onboard processing, and increased reliability for extended missions, including GEO and inter-planetary ones. These challenges and innovations are defining the future of CubeSats and small satellite technologies [176].

To secure the long-term viability of space activities in the face of the development of small satellites and CubeSats, a diversified strategy is required. First and foremost, it is critical to establish comprehensive space traffic control systems [177]. These systems would aid with monitoring and regulating the increasing number of satellites in orbit, reducing the risk of collisions and assuring efficient use of orbital space. Furthermore, strong debris mitigation requirements are required to reduce the environmental impact of space activities. This is accomplished by implementing measures to reduce space debris generation, such as designing satellites for safe reentry or deploying deorbiting mechanisms, which will help to maintain orbital environments for future generations [70]. International collaboration on space policy and regulation will be critical for addressing these problems. Harmonizing standards and regulations across nations can establish a unified framework for sustainable space activities and ensure equitable access to space resources while safeguarding the Earth’s environment. Also, investing in the development of technology for debris removal and satellite recycling is critical [63]. Efforts to develop and deploy spacecraft capable of actively removing debris from orbit as well as repurposing or recycling decommissioned satellites can help to reduce the environmental impact of space activities and contribute to the long-term viability of space operations.

4. Identified Small Satellite Features

The changes highlighted in the previous section improve the technical capabilities of small satellites;

Table 3. Summary of the most notable small satellite trends.

Features	Characteristics Identified in Small Satellites Missions	Challenges and Contributions to a Sustainable Space
Technology miniaturization	More powerful and smaller systems	Reduced volume of space debris
Multiple mission objectives	Satellites with multiple or complementary mission objectives (i.e., constellations)	Flexibility for multi-purpose and reconfigurable missions
Involves high-risk missions	Uses for scientific experiments in risky orbits (i.e., inter-planetary or asteroid)	Satellite missions with high risk but with reliability and reusable satellites
Low-cost trend	Multidisciplinary projects; university, government, and space companies working together; exchanging knowledge and experiences	Use new materials and reduce manufacturing times through innovative methodologies (e.g., additive manufacturing)
Novel developments	Promote more open space access through standardized platforms and reduced satellite sizes	Development of new capabilities for space architectures

shows a summary of the main characteristics and challenges for future generations of small satellites to contribute to a sustainable space.

Additionally,

Table A1. Management & Manufacturing.

Development Type	Category	Item	Mission	Feature	Agency/Institution	Country-Launch Year
Management and manufacturing	Lean methodologies	An orbit reconfigurable satellite	GomX-4*	Reconfigurable Field Programable Gate Array (FPGA) in flight.	GomSpace- ESA	Denmark (2018)
			ArgoMoon*	Fourth-generation flash-based FPGA on a single chip [179].	ASI (Italian Space Agency)- ESA	Italy (2022)
			LINUSS 2*	With a new architecture, users can enhance capabilities and assign new missions through a software update.	Lockheed Martin Space Operations	USA (2022)
			WISA Woodsat	The world’s first wooden satellite.	WISA Plywood- ESA	Finland (2023)
			DAVE	Technological demonstration of mechanical dampers in microgravity.	Cal Poly	USA (2018)
			Virginia CubeSats Constellation	Measure orbital decay to form a database of atmospheric drag for small satellites.	University of Virginia & Hampton University	USA (2019)
			EagleSat-1		Embry-Riddle	USA (2017)
			MakerSat-0	Measure deterioration of polymers used in 3D printing due to exposure to the space environment.	Northwest Nazarene University	USA (2017)
			RadFxSat	To measure the effect of ionizing radiation in memory integrated circuits, especially in CMOS.	AMSAT	USA (2017)
			ARGUS-2		Vanderbilt University	USA (2015)
		3D-printed	LINUSS 2*	Validating capabilities 3D-printed spacecraft components [196]	Lockheed Martin Space Operations	USA (2022)
		Radiation-resistant components	ArgoMoon*	Hardened components by design against radiation-induced SEUs.	ASI (Italian Space Agency)- ESA	Italy (2022)
			LINUSS 2*	High-power radiation-hardened computer.	SHREC research	USA (2022)
		Compact Satellite Bus/ Dispenser/Deployer	ION CubeSat Carrier	Capable to host a combination of CubeSats that fits the volume.	D-Orbit	Italy (2020)
			PPOD (for LightSail-1)	Poly Picosatellite Orbital Deployer.	CalPoly	USA (2013)
			CSD	Canisterized Satellite Dispenser.	RocketLab	USA (2022)
			LINUSS 2*	Docking adapter bus to add new mission capabilities after launch.	Lockheed Martin Space Operations	USA (2022)
		Solar Panels / Sail	NanoSail D. Square, kite-like, rigid solar sails	Solar sail drag device for deorbiting satellites.	NASA	USA (2006)
			Dcubed	Origami Solar Arrays.	Dcubed	Germany
			Miura-ori (proposal)	Miura-ori Origami principle – efficient way to pack solar panels.	JAXA	USA & UK (2020)
				Self-folding mechanism for self-reconfiguration CubeSat.	Oxford Space System
					University of Liverpool
			Ikaros* Spinning disk solar sails	Lightweight, reflective membrane propellant by the sun’s radiation.	JAXA	Japan (2010)
		Antennas	RemoveDebris*	Helical antennas deployable.	University of Surrey - Surrey Space Centre	UK (2018)
			ESAIL	Hold Down and Release Mechanisms [197]	Oxford Space Systems- ESA	USA (2020)
			NORsat-2	Novel Engineering Techniques for Origami-Inspired (Yagi) Antenna Deployment.	Norwegian Space Agency (NOSA)	Norway (2017)
			NovaSAR-1	Deployable wrapped rib SAR antenna and RF system.	SSTL (Surrey Satellite Technology Ltd.), UK, and Airbus DS	UK (2018)
			RainCube*	Ultra-compact deployable Ka-band Cassegrain antenna.	NASA JPL	USA (2018)
		Flight software	Lunar IceCube	The computer language with the lowest error rate.	Morehead State University, NASA	USA (2022)
		Cameras	Cislunar Explorers*	Three onboard cameras are used to capture images of the Sun, Moon, and Earth.	Cornell University	USA (2024)
			GomX-4*	Hyperspectral imaging	GomSpace- ESA	Denmark (2018)
		Payloads: Radar	RainCube*	Ka-band radar technologies.	NASA JPL	USA (2018)
			Ofeq-5 satellite*	Synthetic-Aperture Radar (SAR).	Israel Defence Force	Israel (2002)
			CryoSat-2*	SAR Interferometric Radar Altimeter.	ESA	France (2010)
			ESA’s Hera mission*	First radar probe of an asteroid.	ESA	France (2024)
			MicroSAR*	Can detect relatively small vessels in a large area simultaneously.	Space Norway- Oxford Space Systems	Norway (2025)
		Design	Cislunar Explorers*	Two L-shaped satellites (6U CubeSat).	Cornell University	USA (2024)
		Thrust/ Propulsion/ Propellant	GomX-4*	Highly miniaturized cold-gas.	Nanospace of Uppsala	Denmark (2018)
			LunIR*	Low thrust electric propulsion technology.	Lockheed Martin Space- NASA	USA (2022)
			Lunar IceCube*	Miniature electric RF ion engine system.	Morehead State University, NASA	USA (2022)
			Cislunar Explorers*	Water electrolysis propulsion system.	Cornell University	USA (2024)
			ArgoMoon*	Hybrid micropropulsion system (mono-propellant and cold gas propulsion).	ASI (Italian Space Agency)- ESA	Italy (2022)
			Team Miles	Plasma thrusters.	Team Miles	USA (2022)
			Mono-propellant deorbit stage (MPDS)*	Designed to quickly and precisely deorbit.	SpaceWorks	USA (2023)
		Ground Station	LINUSS 2*	Multi-core hardware to process more data in orbit.	Lockheed Martin Space Operations	USA (2022)

,

Table A2. Disruptive Technologies, Planetary Defense, Biology & Science, Communication/Data Transfer, Support, Earth Observation, Earth Sciences & Interplanetary Probes, and Military Security, Intelligence Surveillance & Reconnaissance (ISR).

Development Type	Category	Item	Mission	Feature	Agency/Institution	Country-Launch Year
Disruptive technologies	Use of disruptive technologies	Blockchain technology.	GomX-4*	Blockchain technology.	GomSpace- ESA	Denmark (2018)
			SIRION PATHFINDER 2	Test IoT communications using blockchain technology.	EchoStar Satellite Services	USA (2018)
		Artificial Intelligence (AI)	FSSCAT*	Image processing [198]	Universitat Politècnica de Catalunya	Spain (2020)
		Quantum technologies	MOZI HAO (MICIUS QKD)	Test ultra-secure quantum communications in orbit.	China Academy of Sciences (CAS)	China (2016)
			TeQuantS project*	Quantum space-to-Earth communication.	ESA with Thales and Leonardo [199]	France (2026)
		Test cloud computing infrastructure	TYVAK 0129 (PATHFINDER RISK REDUCTION)	Prove out RF-enabled swarming formations and space-to-space networking.	NASA Ames Research Center	USA (2019)
		Cloud Computing and Storage Platform	FSSCAT* / 3Cat- 5B	Image processing [198]	Universitat Politècnica de Catalunya	Spain (2020)
			Nebula-ION platform	Uplink and run software and artificial intelligence and machine learning (AI/ML) apps.	D-Orbit	Italy (2021)
		5G and 6G	SpaceX- 2019-074A	Technology standard for broadband cellular networks [200]	SpaceX	USA (2019)
Planetary defense	Against near-Earth objects (NEOs)	Asteroid	DART Mission (Double Asteroid Redirect Test)	Asteroid Trajectory deflection [201]	NASA	USA (2021)
			Hera’s mission	First test of asteroid deflection, with the first rendezvous with a binary asteroid system.	ESA	France (2024)
Biology and Science	Samples		HAYABUSA 2	Rock samples taken from the Ryugu asteroid.	JAXA	Japan (2014)
	Tests on living organisms	Multi-cellular organism	WormSail	First multi-cellular organism on CubeSat flight.	University of Nottingham	UK (2024)
		Radiation studies	BioSentinel	First study of the biological response to space radiation outside LEO [202].	NASA	USA (2022)
Communication/ Data transfer	Inter-Satellite Linking (ISL)	ISL and station keeping capabilities	GomX-4*	Linked through a new version of the SDR (Software Defined Radio).	GomSpace- ESA	Denmark (2018)
	Long-distance	Lunar- Earth	ArgoMoon*	X-Band transponder.	ASI (Italian Space Agency)- ESA	Italy (2022)
	Optical communication	Optical communication	ArgoMoon*	Rangefinder (RF) controls the distance from target.	ASI- ESA	Italy (2022)
	Interplanetary	Mars-Earth	MarCO	Data relay satellite.	NASA JPL	USA (2018)
	Quantum	Quantum Science Satellite (QSS)	MOZI HAO (MICIUS QKD)	Test ultra-secure quantum communications in orbit.	China Academy of Sciences (CAS)	China (2016)
Support	Inspection	Without the involvement of the ground segment	ArgoMoon*	Transmit telemetry and data through different antennas in satellite.	ASI (Italian Space Agency)- ESA	Italy (2022)
	Long-term Services	Astronaut lunar missions	CAPSTONE*	Calculated orbital stability planned for the Lunar Gateway space station.	Advanced Space, LLC. -NASA	USA (2022)
	Other missions	Companion satellite	LICIACube*	Image the collision DART and Asteroid impact.	ASI	Italy (2021)
Earth Observation and Sciences, Interplanetary Probes	Earth Observation	Artic	GomX-4*	Arctic Radiation experiment.	GomSpace- ESA	Denmark (2018)
		Earth	GRACE*	Earth’s gravity field and ionosphere.	NASA	USA (2002)
			CryoSat-2*	Polar sea ice studies.	ESA	France (2010)
	Interplanetary observation	Asteroid	Near-Earth Asteroid (NEA)	Asteroids flying within 0.5 AU of Earth are to be investigated with high resolution camera. NEA Scout target, to be encountered in November 2023.	NASA	USA (2022)
		Sun	HELIOS mission	First close-in measurements of the Sun’s surface and solar wind.	NASA	USA (1978)
			ESA’s Cluster quartet	Study Earth magnetic field the energetic particles of the solar wind.	ESA	(2000)
			CubeSat for Solar Particles (CuSP)	Sun dynamic particles and magnetic fields.	Southwest Research Institute and NASA	USA (2022)
			Proba-3*	Sun’s ghostly corona, or surrounding atmosphere.	ESA	France (2024)
		Lunar	LunaH-Map	Investigate presence of water-ice.	Arizona State University- NASA	USA (2022)
			Lunar IceCube*	Water distribution on the Moon from lunar orbit.	NASA	USA (2022)
			Luna-27	Explore lunar south pole.	Roscosmos	Russia (2025)
			OMOTENASHI	Measurements of the radiation environment.	JAXA- Lockheed Martin Space - NASA	Japan/ USA (2022)
			LunIR*	Low-energy trajectory control technologies Earth-Moon.	Lockheed Martin Space- NASA	USA (2022)
			Luna-26	Lunar orbital mapping mission.	Roscosmos	Russia (2024)
		Mars	MarCO	Communication link to Earth.	NASA JPL	USA (2018)
		Venus	Ikaros*	Venus flyby.	JAXA	Japan (2010)
Military security; Intelligence Surveillance; Reconnaissance (ISR)	Security	Synthetic-Aperture Radar (SAR)	PAZ	SAR satellite with ship identification secondary function.	Hisdesat Strategic Services S.A	Spain (2018)
			RainCube*	Ka-band radar technologies.	NASA JPL	USA (2018)
			Ofeq-5 satellite*	Synthetic-Aperture Radar (SAR).	Israel Defence Force	Israel (2002)
			CryoSat-2*	SAR Interferometric Radar Altimeter.	ESA	France (2010)
			MicroSAR*	Can detect relatively small vessels in a large area simultaneously.	Space Norway- Oxford Space Systems	Norway (2025)
	Cybersecurity	Quantum technologies	TeQuantS project*	Secure cryptographic keys using the quantum properties of light.	ESA with Thales and Leonardo	France (2026)
	Weapon	Anti-satellite weapons (ASAT)	Cosmos 2504	Test version of inspection satellite.	Russian Ministry of Defence	Russia (2015)
	ISR	Intelligence Surveillance and Reconnaissance	TYCHE	Intelligence Surveillance and Reconnaissance (ISR).	UK Space-based	UK (2025)

and

Table A3. Navigation, Science, Technology & Education, Sustainable Space, Maneuvers, On-orbit activities, and Unconventional satellite mission proposals.

Development Type	Category	Item	Mission	Feature	Agency/Institution	Country- Launch Year
Navigation	Optical navigation	Laser Infrared Crosslink	CLICK A	Optical laser communications with a single 3-unit (3U) spacecraft.	MIT Lincoln Laboratory	USA (2022)
		Interplanetary	Cislunar Explorers*	Navigate completely autonomously, with minimal control from Earth.	Cornell University	USA (2024)
	X-ray pulsars	Interplanetary	XPNAV-1*	Determine its location in the solar system within 5 kilometers.	Aerospace Science and Technology Corp	China (2016)
Science, Technology and Education	Novel Instrument	InfraRed Spectrometer	Lunar IceCube*	Broadband InfraRed Exploration Spectrometer (BIRCHES).	Morehead State University, NASA	USA (2022)
		X-ray Telescope	XPNAV-1*	Test background noise of the universe.	China Aerospace Science and Technology Corp	China (2016)
		Space radiation- Telescope	Foresail-1*	Near-Earth radiation environment.	Helsinki University of Technology	Finland (2022)
Sustainable Space	Active Debris Removal (ADR)/ Docking	Life extension	MEV-1* Mission Extension Vehicle (MEV)	Attached to INTELSAT 901 to provide 5 year life extension.	Space Logistics LLC (Northrop Grumman)	USA (2019)
		Deorbit/ with no docking interface pre-installed	ClearSpace-1	Mission to de-orbit space debris with non-cooperative platforms	ESA	France (2025)
		Service, Inspection and Removal	DART	Demo of Autonomous Rendezvous Tech.	NASA	USA (2005)
			ADRAS-J1	Removing large-scale debris from orbit.	Astroscale (Japan)	Japan (2024)
			ATV Europe’s Automated Transfer Vehicle	Dispose of Space Station waste.	ESA	(2018)
		Capture system /propulsion system	MEV-1* Mission Extension Vehicle (MEV)	A satellite in a graveyard orbit was captured and returned to operational status.	Space Logistics LLC (Northrop Grumman)	USA (2019)
		Green propellant	Mono-propellant deorbit stage (MPDS)*	High-thrust chemical propulsion stage utilizing environmentally-friendly liquid propellants.	SpaceWorks	USA (2023)
		Capture Method- Magnetic Capture	ELSA-d CHASER	Demonstrates magnetic capture in space.	Astroscale	UK- Japan (2021)
		Capture Method- Net	RemoveDebris*	Wrapped and entangled the target.	University of Surrey - Surrey Space Centre	UK (2018)
		Capture Method- Harpoon	RemoveDebris*	Tethered Harpoon test.
		Capture Method- Claw	ClearSpace-1*	Clearspace-1 will capture and safely deorbit a large derelict object.	ESA	France (2025)
		Capture Method- Tether	Dragracer A, B (Alchemy, Augury)	Terminator Tape deorbiting device.	TriSept Corp	USA (2020)
		Laser Orbital Debris Removal (LODR)	EOS Space Systems Space Debris Management	High energy laser pulser radiation.	EOS Company	Australia (2022)
		Self-destructing- magnetic tugboat	In study- proposal	Magnetic tugboat debris capture system [203]	ESA- Institut Supérieur de l’Aéronautique et de l’Espace	France (2017)
		Self-destructing-plasma brake	Foresail-1*	Bring spacecraft back into the atmosphere.	Helsinki University of Technology	Finland (2022)
		Spinning Magnets	In study- proposal	Dexterous magnetic manipulation of conductive non-magnetic objects.	University of Utah	USA (2021)
		Mechanic capture	ASTRO - ORBITAL EXPRESS 1	Robotic arm for servicing missions.	DARPA Satellite Operations (Op.)	USA (2007)
	Reusable vehicles	Space Transportation Systems	Space Rider	Combining reusability, in-orbit operations, and transportation [204]	ESA	France (2023)
	Implement technics	Gobble up space debris	ClearSpace-1*	The satellite will capture the small SwissCube satellite using a conical net before destroying it in the atmosphere.	ESA	Switzerland (2025)
Maneuvers	Formation flying	Fly in close formation	TerraSAR-X and TanDEM-X	SAR Interferometry.	DLR – (German Aerospace Center)	Germany (2007)
	Maneuver	Collision Avoidance Maneuver	Proba-3*	Rendezvous experiment in elliptical orbit [205]	ESA	France (2024)
	Cluster	Cluster formations	ESA’s Cluster quartet	Feet of 4 spacecraft to study plasma phenomena in 3 dimensions.	ESA	Germany (2000)
	Constellations	Satellite constellations	Starlink	Satellite Internet access.	SpaceX	USA (2019- 2022)
	Fractionated	Picosatellites’s formation	ANDESITE	Ad-hoc Network Demonstration for Extended Satellite-based Inquiry and other Team Endeavours [206]	Center for Space Physics (CSP)	USA (2020)
	Retrograde orbit	Lunar	CAPSTONE*	Near polar lunar orbit.	Advanced Space, LLC. -NASA	USA (2022)
		Earth	Ofeq-9	Satellite operates in retrograde low Earth orbit.	Israel Defence Force	Israel (2010)
	Deep space	Lunar	ArgoMoon*	Propulsive maneuver to close in a geocentric orbit.	ASI- ESA	Italy (2022)
On-orbit activities	Servicing missions	Cargo delivery, Satellite retrieval	DART	Autonomous rendezvous operations.	NASA	USA (2005)
		Demonstrating new technologies	Hera’s mission	First probe to rendezvous with binary asteroid system.	ESA	France (2024)
		Assembly and Manufacturing	OSAM-1	Demonstration of manufacturing using 3D printing of 10m beams.	NASA	USA (2025)
Unconventional satellite mission proposals	HAPS (High Altitude Pseudo-Satellite)	Stratospheric platform for COMMS or EO	Ecosat Airships	Solar Airship for communications and observation applications.	Capgemini Engineering	Spain (2021)
	High-altitude platform services.	Geo-synchronous high-altitude payload platform	Sitallite	Communication platform within a 1000 km diameter range [207]	VanWyn, Inc.	Canada (2021)

in Appendix A present a comprehensive historical study analyzing the most significant technology demonstrations and their respective purposes. The selection of relevant technologies was based on their development nature and applicability to specific missions.

The types of development are categorized into thirteen distinct classifications; each is described and detailed in the corresponding column. In some cases, the category column includes further subdivisions based on the mission’s specific objectives. The thirteen types of development classified are as follows:

Table A1:

• Management and Manufacturing: satellite missions focused on introducing novel components, materials, and manufacturing techniques as primary or secondary goals [178,179,180,181,182];

Table A2:

• Disruptive Technologies: satellite missions that test new technological capabilities [183];
• Planetary Defense: satellite missions designed to protect Earth from potential celestial bodies that could have negative impacts in the event of a collision [178,184];
• Biology and Science: missions involving scientific experiments that explore the behavior of microorganisms in a space environment;
• Communication/Data Transfer: missions primarily aimed at developing new communication methods in space;
• Support: satellites serving as assistance for other satellites with payloads, focusing on supporting primary objectives;
• Earth Observation, Earth sciences and interplanetary probes [185];
• Military Security, Intelligence Surveillance and Reconnaissance (ISR);

Table A3:

• Navigation [186];
• Science, Technology and Education: this classification serves educational purposes, primarily targeting leadership in universities and research centers, with objectives centered around scientific and technological demonstrations;
• Sustainable Space: satellite missions focused on facilitating initial space pollution mitigation efforts and establishing a foundation for ongoing space sustainability initiatives;
• In-orbit Activities: missions aiming to utilize existing satellite capabilities for operations in the space environment;
• Unconventional Satellite Missions: showcasing novel capabilities and structures within satellite technology.

Considering the features identified in Table A1, Table A2 and Table A3, they can be classified into four methods: (1) ADR, (2) transport logistics, (3) mission extension, and (4) repair and construction, as illustrated in Figure 12. These methods could be considered for future developments, with a focus on maximizing the potential of satellites to provide services and technologies.

(a)

Active Debris Removal (ADR): Space debris, which includes decommissioned satellites and other fragments, presents a growing threat to the safety and functionality of operational satellites. The implementation of effective active debris removal (ADR) methods is vital for establishing and maintaining a sustainable space environment. In Table A3, this is categorized as Active Debris Removal (ADR)/Docking, and we delve into state-of-the-art ADR technologies and strategies, such as deorbiting with no pre-installed docking interface, capture systems with integrated propulsion, self-destructing magnetic tugboats, space transportation systems, and space debris “Gobblers”, among others. This examination underscores the significance of proactive debris management for mitigating collision risks and preserving orbital space for future satellite deployments.

(b)

Transport Logistics: Efficient logistics and transportation systems are important for ensuring the successful launching, deployment, and repositioning of satellites. In Table A1, categorized under “Management and Manufacturing Techniques”, we delve into cutting-edge logistics solutions, including technologies like orbit-reconfigurable satellites, radiation-resistant components, 3D printing, and other innovative approaches. These solutions are purposefully designed to not only reduce the environmental impact of satellite launches but also to optimize satellite placement for maximum efficiency.

(c)

Mission Extension: Extending the operational life of satellites is not only an economically sound approach, but it also environmentally responsible. We delve into innovative mission extension technologies, such as satellite servicing and in-orbit refueling, as sustainable methods for prolonging the lifespans of satellites and reducing the necessity for new deployments. In Table A2, we showcase a range of developments (e.g., disruptive technologies, communication and data transfer advancements, and innovations in military security and intelligence surveillance and reconnaissance (ISR)). These developments encompass innovative payloads aimed at optimizing satellite performance and ensuring the continued success of missions.

(d)

Repair and Construction: Satellite repair and in-orbit construction capabilities are imperative for mitigating the environmental impact caused by outdated and malfunctioning satellites. In Table A4, we explore the development of autonomous construction and repair techniques, encompassing on-orbit assembly and component replacement [187,188,189]. These approaches are instrumental for extending the operational lifespan of satellites while concurrently minimizing the generation of space debris [190].

As depicted in Figure 12, these parameters collectively represent a comprehensive framework for advancing the sustainability of satellite architectures. Future developments in these areas hold the promise of more reliable and environmentally friendly satellite technologies that are well-equipped to meet the growing demands for space-based services and technologies [191].

5. Conclusions and Future Research

The design of an eco-friendly logistics satellite supply chain requires the collaboration of multiple stakeholders. This study has highlighted the significant technological advances within specific sections of the supply chain. For instance, in the manufacturing stage, the proposal of utilizing new materials with sustainable characteristics for space applications shows promising progress. In the launch stage, the implementation of intelligent dispenser technology enhances satellite deployment accuracy, thereby reducing the risk of mission failure. Additionally, the operation stage has witnessed the emergence of projects aimed not only at fulfilling scientific objectives but also at prolonging the satellite’s lifespan. Sustainable practices such as in-orbit repair, ADR, and environmentally responsible satellite disposal methods following mission completion are proposed in this segment.

Future research on this subject must consider political, legal, economic, and security consequences. The concept of a satellite “as a service”, similar to a multi-owner property, offers potential to reduce the number of space assets by allowing satellite resources to be reconfigured in orbit for different customers at different times. Furthermore, the rapid evolution of on-orbit servicing (OSS) creates several obstacles and opportunities. OSS technologies such as in-space repairs, refueling, refurbishing, and service have the potential to dramatically extend satellite lifecycles while also addressing space debris concerns. For example, more than half of GEO satellites are predicted to have operational issues owing to fuel depletion, but refueling can extend their operational life, keep orbital slots, and benefit both governmental and commercial operators. Companies such as SES and Intelsat are incorporating OSS life extension capabilities into their business models, demonstrating increased customer confidence [70,192]. Recent investments have highlighted the importance of these technologies. The launch deal between SpaceLogistics and SpaceX as well as the U.S. Air Force’s investment in Orbit Fab’s refueling interface demonstrate the strategic value of OSS. Refueling improves mobility, allowing satellites to retain or alter orbits, respond to threats, and avoid collisions, all of which are critical for the resilience and agility of space infrastructure [192]. The rapid evolution of OSS presents numerous challenges and opportunities. Recent initiatives such as Clean Space by the ESA and collaborations on projects like Astroscale, ClearSpace, D-Orbit, and Telespazio, alongside Thales Alenia Space, demonstrate a growing commitment to advancing OSS technologies [193]. These initiatives have received funding to mature their ideas, and their results were presented in preparation of the 2022 ESA council at the ministerial level [193]. Additionally, the development of modular spacecraft designed for serviceability, including refueling and upgrades, can further extend the lifespans of satellites and improve functionality as technology evolves. This modularity reduces costs and launch weights while enabling on-orbit assembly and repair, fostering a robust secondary market for older-but-functional spacecraft. This shift towards modular and serviceable designs will likely become standard by the end of the 2020s, driven by initiatives like the U.S. Defense Innovation Unit’s Modularity for Space Systems (M4SS) project [194]. Furthermore, the adoption of safety standards, exemplified by the JAXA’s JERG-2-026 “SAFETY STANDARD FOR ON-ORBIT SERVICING MISSIONS” [195], underscores the importance of establishing regulatory frameworks to ensure the safe and effective operation of OSS missions. Exploring these topics in depth will provide significant insights for policymakers, legal experts, and industry professionals as they navigate the changing landscape of sustainable space logistics.

The article outlines critical methods for future Eco-LeanSat designs that balance environmental responsibility and performance enhancement. Primarily, the adoption of sustainable materials and manufacturing processes assumes an important role in mitigating the ecological footprint associated with satellite production. This necessitates the sourcing of materials from renewable or recycled sources and the minimization of waste throughout the manufacturing process. To accomplish this, rigorous material testing and the establishment of regulations conducive to the integration of these novel materials into space missions are imperative. For example, the LignoSat mission [68], as mentioned in the article, employs wood in satellite construction, exemplifying an innovative approach to sustainability. Moreover, research into advancements in 3D-printing technology for satellite fabrication is underway, furthering the development of environmentally friendly satellite designs that leave no harmful particles on Earth or in space. Demonstrating the successful adoption and implementation of these materials opens the door to further exploration and study in the realm of spatial sustainability. Second, boosting energy efficiency is critical for maintaining environmental responsibility. Eco-LeanSat designs might include innovative energy management systems and energy-efficient components to reduce power usage during satellite operation. Additionally, incorporating solar panels or other renewable energy sources can help to lessen dependency on nonrenewable energy sources. Furthermore, using eco-friendly propulsion solutions, such as electric propulsion, might improve environmental sustainability.