Hazel Levine
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README.md
Good Plan? Great Plan!
Category: Space and Things Points (final): 77 Solves: 54
Help the Launchdotcom team perform a mission on their satellite to take a picture of a specific location on the ground. No hacking here, just good old fashion mission planning!
The current time is April 22, 2020 at midnight (2020-04-22T00:00:00Z). We need to obtain images of the Iranian space port (35.234722 N 53.920833 E) with our satellite within the next 48 hours. You must design a mission plan that obtains the images and downloads them within the time frame without causing any system failures on the spacecraft, or putting it at risk of continuing operations. The spacecraft in question is USA 224 in the NORAD database with the following TLE:
1 37348U 11002A 20053.50800700 .00010600 00000-0 95354-4 0 09 2 37348 97.9000 166.7120 0540467 271.5258 235.8003 14.76330431 04
You need to obtain 120 MB of image data of the target location and downlink it to our ground station in Fairbanks, AK (64.977488 N 147.510697 W). Your mission will begin at 2020-04-22T00:00:00Z and last 48 hours. You are submitting a mission plan to a simulator that will ensure the mission plan will not put the spacecraft at risk, and will accomplish the desired objectives.
Write-up
In the time range [2020-04-22 00:00:00, 2020-04-23 23:59:00], the USA 224 satellite as given in the TLE above reaches the Iranian space port twice:
- Around 09:28 on 2020-04-22
- Around 09:50 on 2020-04-23 This was found in GPredict after loading in the TLE given in the netcat.
Additionally, the USA 224 reaches the ground station in Alaska twice:
- Around 10:47 on 2020-04-22
- Around 11:10 on 2020-04-23
The rest of the strategy is pretty much just to use trial and error:
- Image for as long as possible until the battery runs dry or we're out of range
- Downlink for as long as possible until the battery runs dry or we're out of range
- Desaturate the wheels about an hour before they exceed maximum velocity
Full plan
2020-04-22T00:00:00Z sun_point
2020-04-22T09:28:00Z imaging
2020-04-22T09:35:00Z sun_point
2020-04-22T10:47:00Z data_downlink
2020-04-22T10:50:00Z wheel_desaturate
2020-04-22T11:30:00Z sun_point
2020-04-23T08:50:00Z wheel_desaturate
2020-04-23T09:30:00Z sun_point
2020-04-23T09:50:00Z imaging
2020-04-23T09:56:00Z sun_point
2020-04-23T11:10:00Z data_downlink
2020-04-23T11:14:00Z sun_point
2020-04-23T22:00:00Z wheel_desaturate