moeriscus t1_iu2qrbm wrote on October 28, 2022 at 2:55 AM

Reply to comment by alle0441 in NASA spacecraft records epic ‘marsquakes’ as it prepares to die by marketrent

Fair point, but I think it's obvious that NASA lowballs the expected lifespans in order to avoid overpromising/underdelivering to the public and to budgetary committees

Lasombria t1_iu2xp16 wrote on October 28, 2022 at 3:55 AM

My father worked for JPL for 40+ years, and no, they really don't. What they do is make the projected lifespan as guaranteed as possible. A happy side effect of that is these great extended-mission lifespan, but the goal is hitting the primary lifespan securely.

moeriscus t1_iu2yxy9 wrote on October 28, 2022 at 4:07 AM

Ah, thank you for your insight!

Lasombria t1_iu385pf wrote on October 28, 2022 at 5:47 AM

Glad to help. :) Dad loved to about distinctions like that.

Dsiee t1_iu3txgw wrote on October 28, 2022 at 10:47 AM

No, it is an artificat of designing for a high sucess probability. For a simple example, let's say you want a robot for a 1 year mission with 90% probability of it lasting two years. You design the robot so that it has a failure rate of 5% per year. As a result it is highly likely (~80%) that it will last four years or twice the required mission length.

Obviously this is a very simplified example, but hopefully it illustrates the point that you cannot easily determine the exactly lifespan of a piece of equipment.