How to avoid a BSOD on your 2 billion dollar spacecraft

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2024-09-25 19:00:05

The lifecycle of most spacecraft consists of a final phase where all the systems are tested to various levels of synergy. One of the most important and complex set of tests are the Closed Loop Tests (CLTs), where the spacecraft is sent simulated orbital data, and then its attitude response is observed. It’s a closed loop because the attitude telemetry is fed back into the simulation while the test is occurring, effectively making the spacecraft and whatever hardware is currently being used part of the simulation. This particular test involved observing the response from control thrusters on the spacecraft when commanded to perform a slew and engine burn to a transfer orbit.

To get the spacecraft response data back to in the loop, a set of memory addresses mapped to the sim needs to be uploaded onto the spacecraft RAM. These memory addresses were not determined while this test was being developed. Instead, a set of placeholder addresses meant for the previous spacecraft was used in the development environment.

Ok, fair enough. When we’re developing our tests prior to them being run on the spacecraft, it’s useful to have something to upload, even if it’s not the final product.