Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This article investigates the MS-MG (multiple satellites and multiple ground stations) planning problem and proposes a mixed-integer linear programming (MILP) model. The model is based on the concept of a time-space network (TSN) and considers constraints related to the space mission environment of the satellites. It establishes a Vehicle Routing Problem with Pickup and Delivery (VRPPD) model for satellite loading and unloading vehicle paths and verifies it through numerical experiments based on actual satellite data from South Korea.

 

Due to Earth's rotation, satellites have limited time windows for task execution and communication with ground stations. Therefore, it is necessary to plan both the satellite's tasks and communication time effectively.

 

The innovations of this article are:

1. Introducing a VRPPD problem model that considers satellite storage capacity constraints while planning satellite observation tasks and instruction upload and download for multiple vehicles.

2. Solving the model using test data and actual satellite operation data on the CPLEX solver to validate its effectiveness.

3. Partitioning the time windows for utilization efficiency by using the continuous variable of task execution start time.

 

The article has the following issues:

1. The index representation  in Constraint (3), the first summation symbol, is inconsistent with the explanation. It should be changed to i∈N\U.

2. The descriptions of Constraints (7) and (8) are not clear enough.

3. The direction of the inequality in Constraint 30 is incorrect.

4. The mathematical model established in this article has numerous set-based constraints, making it difficult to have a unified modeling approach. Describing it becomes challenging for large problem sizes.

5. The experimental data used in the article is too small, and there are no comparative experiments, reducing the persuasiveness of the experimental results.

6. In addition, some new references on EOS scheduling should be included:

 

Ou J, Xing L, Yao F, et al. Deep reinforcement learning method for satellite range scheduling problem[J]. Swarm and Evolutionary Computation, 2023, 77: 101233.

 

Jianjiang Wang, Guopeng Song, Zhe Liang, et al. Unrelated parallel machine scheduling with multiple time windows: An application to earth observation satellite scheduling. Computers & Operations Research, 2023, 149: 106010.

Comments on the Quality of English Language

English writing should be improved

Author Response

The authors greatly appreciate your comments. Please refer to the attached file. Thank you.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

I am not an expert in satellite mission allocation procedures, and the core mathematics behind the method are nearly impossible to verify without doing all the research yourself. However, from the presentation quality and results correctness (some mission sequences in Table 12 are easy to check for “dumb” results from the orbital dynamics perspective) I conclude that the methodology works. TSN graph is a nice visualization tool for this problem. I have some minor remarks, but in general support the manuscript publication.

1.       Lines 31-32. Expectations are given for years 2022 and 2023. It is 2024 now.

2.       Figure 1 has low quality.

3.       Line 162. VTW requires a full name of the acronym. Only one page later in Figure 3 it becomes clear that this is visibility time window? Also, what do brackets mean in [AOS,LOS]?

4.       Line 168, Figure 2a. It is not clear why VTW is different for different bandwidth. Why different lines on the visibility cone are drawn for X and S bands? How exactly these lines are drawn?

5.       Lines 176-177. What is 100, 180 etc? AOS is “start of visibility”. “Start” cannot be measured in numbers. Start time, start declination angle may be measured. This is actually a continuation of Remark 3.

6.       Line 214. I think that it is bad to refer to all equations from 1 to 42. Refer to equations below, equations in this section or something similar.

7.       Line 312. Split time is arguably bad. The satellite should try to transmit all its data in one package to avoid confusion and special procedures of the data collection. Maybe this is a future work idea, to include a soft restriction on split communication windows: it is better to avoid split, but if it is not possible, then split is allowed.

8.       Lines 338-339. The choice of mission areas is confusing: obviously civilian Rio and Tokyo and obviously military North Korea and Iran. I do not ask to change the results of course, just mentioning.

 

Comments on the Quality of English Language

English is generally OK, but some obvious typos exist, and a number of times a word is divided in two parts by "-" in the middle.

Author Response

The authors greatly appreciate your comments. Please refer to the attached file. Thank you.

Author Response File: Author Response.pdf