2y ago

Rumbles of a programing error causing the Russian Lunar mission failure.

twitter.com /katlinegrey/status/1693638624678412639

Perhaps the 84 second burn overflowed the integer (2^{6) and was caught by a 2}7s check (127s)

25 comments

there's no way engine burn time is graduated in seconds on a spacecraft in 2023, that's way too coarse
- i can see doing one burn that is kind of rough, then evaluating the situation and applying some correction?
- Why do you expect the Russian space program to be using new equipment after the antique show of an invasion in Ukraine?
  
  Every country uses a combination of older and newer equipment in any war. The war propaganda wizards just try to make things like that look unique to Russia.
  
  Looking forward to T-18 sightings by this time next year . . .
Why in God's name would you use a 6-bit signed integer for anything on a spacecraft? I know space-certified chips are pretty barebones, but surely not that bare bones...
- This is Roscosmos we're talking about here. First lunar mission in 25 years??
The tweet you link didn't indicate that. It said that an engine failure likely caused the overrun, running for 127 seconds instead of the planned 84. Why would something have a 2^7 int size check?
Edit: Quoted
The head of Roscosmos Yuri Borisov said that the main cause of the #Luna25 crash was an engine failure. Instead of the planned 84 seconds, he worked 127 seconds.
Am I missing something?
- There's further discussion of possible explanations in the replies
  
  Ah I think it's Twitter's new thing where you can't see replies of your not logged in.
what do we say to the god of software bugs ruining our space exploration? not today!
one of these days we will finally say it, but... not today 😆
https://en.wikipedia.org/wiki/List_of_software_bugs#Space
- Not today, because the date overflowed a counter somewhere.
  
  Days since last timezone incident: -1
- Yes! I was hopeful after the close failure a few years ago!
- Mistakes happen. For example, may I introduce you to NASA's 125 million dollar Mars Climate Orbiter, which spent most of a year traveling to the Red Planet before ignominiously burning up because a Lockheed Martin programmer decided to write the thruster-firing calculations in Imperial units (feet and pounds) instead of following the specifications to use metric units (meters and kilograms).

25 comments