Mission Design and Orbit-Attitude Control Algorithms Development of Multistatic SAR Satellites for Very-High-Resolution Stripmap Imaging

Round 1

Reviewer 1 Report

I am concerned about the specifics given in Table 1. This is clearly a military application and I do not feel comfortable supporting such research, even when it is of high quality as reported here.

If the Table 1 contents could be made more general, without references to specific vehicles and equipment and key targets, I would recommend publication. If the Table 1 contents are not made more general, I will not be further involved in the review process.

Author Response

Please see the attached file.

Author Response File: Author Response.docx

Reviewer 2 Report

 

The paper “Mission design and orbit-attitude control algorithms development of multistatic SAR satellites for very-high-resolution stripmap imaging” is devoted to formation flying mission design. The paper is well-written and it is of high scientific quality, it will be interesting for the specialists in SAR systems. There are several comments and suggestions, that could improve the text quality.

It seems that the paper contains several redundant sections, the length of the text could be reduced – it would be better for the readability. For example, section 4.4 “Modeling of the 4-axis reaction wheel system” contains nothing new, it can be omitted.

The authors refer only to the national defense application of the proposed SAR mission, the civil applications also should be emphasized in the text.

It is strongly recommended to place the Figures after its first mentioning in the text, not before as it is in the text now.

 Equations (1) and (2) are the same, which seems to be a typo. Please, correct.

 

 It is not logical, that the authors placed the thrusters requirements analysis (Section 3.1.) before the estimation of the required delta_V consumption. It would be better to place this subsection to the end of Section 3, after the numerical simulation results.

 

 According to Fig. 6 the distance between the satellites is 6 km. It is not clear why the authors use distance of 7,5 km in simulations (table 3), referring to the results from not yet presented section 5? More comments are required.

 According to the equation (13) there is no trust along the radial direction during the maneuvering. Why is there a line in “R” axis in figure 9a, then? If it is zero, it could be omitted.

 Line 245. Typo in word “Starlink”.

 Line 351. Designation “D” was never used in the text.

 What are the initial conditions for the numerical simulations in Section 3.3?

 Typo in Fig. 8(a) in y-axis label “aδa”. Should be just “δa”.

 Requirement (3) (line 475) is not clear. What means “the attitude control must be completed at least 0.7 s”? What is the reason for this requirement?

 It can be concluded from Fig. 13 that geometrical RADN is very inaccurate. Is there some way to improve the geometrical calculations without numerical search?

 Attitude motion equations (24) are quite inaccurate in the common case. Even during tracking of the fixed point on the Earth, the gyroscopic terms “ωxIω” and  “hxIω” influence the stabilization accuracy greatly. In this case the PD-like controller (25) should contain the terms for the gyroscopic torque compensation (along with the gravitational torque compensation). The accuracy results obtained by numerical simulations was achieved using motion equations (24) or initial equations (22)?

 Line 623. Instead of “moment of inertia” should be “tensor of inertia”. The same in Table 6. The values of the axial inertial moments do not satisfy the requirements I_x+I_y>I_z, the inertia tensor is not correct.

 Figure 24b. In x-axis label should be “Range”.

 

Author Response

Please see the attached file.

Author Response File: Author Response.docx