Developing Mars lander software

[Jesse Phillips]

On Wednesday, 19 February 2014 at 05:53:55 UTC, Tolga Cakiroglu 
wrote:
> I think only knowing that it has failed is not enough. Because 
> the process is landing, and other CPU should know where the 
> process is left. With that heatbeat signal, only option is that 
> all sensor information must be sent both CPUs continuously and 
> sensor values should be enough about what next step to be 
> taken. Then I think it can continue the process flawlessly.

I don't think watching the video answered this, but it hinted 
toward the second CPU being inactive during landing, if something 
went wrong the CPU would need to be awoken at which point the 
backup CPU would take in all the readings from different sensors 
to decide on actions (possibly it is intended only to land the 
rover and not land the rover in the correct location.)

What was interesting from the video is that the second CPU was 
going to be turned off for the landing and not used as a backup. 
A year before landing (I guess that means 3 months before launch) 
they decided to create the backup software if the main CPU failed 
during landing, it didn't.