Interplanetary Student Nanospacecraft: Development of the LEO Demonstrator ESTCube-2

Round 1

Reviewer 1 Report

Review report of the paper entitled: “Interplanetary Student Nanospacecraft:

Development Lessons from the LEO Demonstrator” by Dalbins et al.

 

The paper contains a detailed description of the ESTCube-2 mission. The paper focus on describing the different payloads and subsystems, but it also included section on lessons learned and management problems. 

 

Student CubeSats are today an important and integrated part of research and education and the paper provide a comprehensive overview of designing and building a student CubeSat that should be read by anybody who intend to build a student CubeSat. 

 

With a few exceptions, the paper is well written and well-structured and I am thus happy to recommend publication, when these exceptions have been corrected.

 

Major comments

1)

Title: The focus of the paper is on the ESTCube-2 mission, so this should be reflected in the title. Also, given that the satellite has not been launched yet, I think it is too early to talk about ‘lessons from’.

 

2)

Abstract: Needs to be rewritten as it does not follow the standard of the rest of the paper. 

Apart from mentioning the payload in the abstract, I also suggest that you mentioning the avionics stack system. There should be a more clear read line between the background, methods, results and conclusions as provided in the abstract.

 

3)

I would like to see a discussion of the launch preparation and the various tests that has been and needs to be performed: vibration, vacuum, thermal etc. 

 

4)

A timeline is mentioned by not provided. When were the different system delivered? When were they integrated, tested and delivered?

 

5)

With a few modifications figure 1 could be used as a graphical abstract.

 

Also, it is not common practice to include specific author information on figures. If these people contributed to the paper, they should be included in the author list.

 

4)

Figure 3 and 4 looks really good, but are hard to follow. I do not follow, how the spin rate change is illustrated in figure 3. 

 

5)

Provide more details about why the orientation of the nozzles of the propulsion system in the Z direction is suboptimal. Provide estimated on moments of inertia in the three axis.

 

6)

Mass, power and link budgets should be provided.

 

7)

I like the section on satellite development lessons, but I think is sound a little too much like and apology as it is now. The whole idea with this project is that you would learn from it and that is hard to do if you do not do mistakes. Instead of focusing on the mistakes, I suggest to focus on recommendation. Maybe provide that 10 most important recommendation is a table and then describe them and why you give them. This also apply to the section on management.

 

 

 

Minor comment

1)

Acronyms should be defined the first time they appear in each of three sections: the abstract; the main text; the first figure or table. When defined for the first time, the acronym should be added in parentheses after the written-out form.

 

2)

Line 35: -> the launching of many small satellites

 

3)

Line 46: -> A deorbiting device that will allow satellites to comply with the 25-year rule [4] or the 5-year rule, recently announcement by the Federal Communications Commission (FCC) [5], can significantly increase development and launch costs. A lightweight deorbiting device is thus crucial for cost reduction of debris mitigation.

 

4)

Line 80: -> lessons learned from ESTCube-1 [9].

 

5)

Line 82: -> the program

 

6)

Line 92: -> However, the ESTCube-1 tether

 

7)

Line 93: -> on board Aalto-1 that did also not deploy

 

8)

Line 94: -> In the wake of the ESTCube-1 tether

 

9)

Line 98: -> The program accepted

 

10)

Line 102: -> from an experimental

 

 

11)

Provide a distance scale to figure 2.

 

12)

Line 159: -> The IPB payload is system developed by the Finnish Meteorological Institute based on the Coulomb drag propulsion (CDP) technology.

 

13)

Line 184: -> Sentinel-2 bands 4 and 8a

 

14)

Line 201: -> The CTS experiment will

 

15)

Line 245: -> The mechanical structure of ESTCube-2 was

 

16)

Figure 9: Where is the AOCS located? Same question goes for figure 10.

 

17)

What is the size and weight of the reaction wheels.

 

18)

Line 450: -> using the centrifugal force

 

19)

Line 479: -> to develop the entire satellite platform

 

20)

Line 548: -> Even though the 

 

21)

Line 562: -> We were talented enough

 

22)

Line 626: -> Unfortunately, the prolonged confinement meant that the students  

 

23)

Line 676: -> The ESTCube-2 project became complex and

 

24)

720: Should be change to something like: This paper describes the development of the ESTCube-2 CubeSat, including the design of the CubeSat and its different subsystems, the construction and testing of the CubeSat and how the project was managed and lead.

Are included in the minor comments.

Author Response

Here is the list of actions taken for each reviewer’s comments. The comment is reminded, and the action taken is summarized in italic.

The authors thank the reviewers for their valuable comments that helped clarify the paper and, hopefully, increase its quality for its future readers.

Janis Dalbins

Author Response File: Author Response.pdf

Reviewer 2 Report

This paper presents an overview of ESTCube-2 spacecraft and discuss the main challenges encountered by the team. A list of lessons learned and some suggestions for future projects are also discussed.

The paper is well structured and all the relevant points not deeply introduced are referenced; only a few minor points might be addressed by the authors.

1.      In the text, it was not specified that the spacecraft has a 3 unit size; this information is reported only in figure 8.

2.      On line 185, the authors state that they expect “some discrepancies” with data from Sentinel-2b cameras. However, this point is not further discussed. Please remove the sentence or better explain the expected discrepancies.

3.      Lines 215-218, it is not really clear how the discussed designs for LEO constellations are related to interplanetary spacecraft. Please clarify it.

4.      Line 245, a few words are missing at the beginning of the line.

5.      Line 460, it is not clear how not being based on the CubeSat standard is an advantage for this subsystem.

6.      Lines 463-466, the custom-made antenna description is placed in the “COTS” subsection. This could create a certain confusion. Maybe, it could be stated that despite that the majority of the subsystem is COTS and the antenna is custom.

Author Response

Here is the list of actions taken for each reviewer’s comments. The comment is reminded, and the action taken is summarized in italic.

The authors thank the reviewers for their valuable comments that helped clarify the paper and, hopefully, increase its quality for its future readers.

Janis Dalbins

Author Response File: Author Response.pdf

Reviewer 3 Report

This paper provides a detailed systems design of the ESTcube-2 cubesat. Programmatic aspects of a small satellite project and discussed and lessons leant described. 

De-orbiting technology is key towards the sustainable implementation of small satellite constellations. The presented methodology could potentially minimize the risk of debris posed by conventional drag devices.

While the information provided is comprehensive, a more formal systems engineering approach applied to this description will enhance it effectiveness to the reader. It will be interesting to see the systems engineering approach adopted for EST-Cube 2. A description requirements traceability matrix, key risks and risk reduction activities will greatly enhance the current paper.

This work will serve as a useful reference for groups undertaking cubesat systems engineering. I would recommend this article for publication.

The language used is clear and easy to understand. The document must be checked for minor typos.

Author Response

Here is the list of actions taken for each reviewer’s comments. The comment is reminded, and the action taken is summarized in italic.

The authors thank the reviewers for their valuable comments that helped clarify the paper and, hopefully, increase its quality for its future readers.

Janis Dalbins

Author Response File: Author Response.pdf