5 ms·

the altimeter? Surely you would put three on there?

mattlondon 2y ago
+1 They had the altimeter fail on the previous mission too. Seems like a fairly crucial component of a moon lander. Armchair rocket scientist here, but if I were on that engineering team I'd lobby hard for less science payloads and more backups for critical instruments for the actual flight of the craft. The rover and hopper and drill etc all sound cool yes, but worthless if you can't land. Again. For the second time. Because the same critical component failed, again. With apparently no backup, again. Of course, it sounds so simple. I am sure there is more to it (e.g. perhaps they had backups and everything worked, but they just weren't fit for purpose?)
- T-A 2y ago
  > They had the altimeter fail on the previous mission too. Not really. They forgot to toggle the safety switch on before launch, so the laser could not be used: https://spaceq.ca/simple-error-could-have-resulted-in-intuitive-machines-mission-failure/ https://spaceq.ca/simple-error-could-have-resulted-in-intuit...
JonChesterfield 2y ago
Had two. One showed so much measurement noise they couldn't trust it, other kept cutting out. Not great.
- lionkor 2y ago
  So three ones, two different models, one in a different location. These are like... basics, no?
  - ricardobeat 2y ago
    If you multiply every critical component by 3x there will be no room left for anything else.
    - lionkor 2y ago
      Well the way they did it (twice) means they had space for other stuff, and of course also failed because they didn't have enough redudancy
    - uoaei 2y ago
      slippery slope fallacy. just do engineering good
    - pclmulqdq 2y ago
      2n + 1 is a basic minimum amount of redundancy for anything critical in a high-value space mission.
      - adastra22 2y ago
        This isn't a high-value space mission.
        pclmulqdq 2y ago
        The price of a ride to the moon alone would make this "high-value." Cubesats are an example of when you can get away with no redundancy, but this is not a cubesat.
        adastra22 2y ago
        This is best compared to being a lunar landing cubesat. IM is an order of magnitude cheaper than a comparable NASA lander. Cheap is the point, and cheap carries with it some concessions to risk.
        pclmulqdq 2y ago
        $1M was the amount they spent on the lander. If I recall correctly, they got a ride to the moon for free. Delivering that amount of mass to the moon is worth O($10M). It seems incentives were not properly aligned for this group. I should also point out that you can fly a scientific mission on a 1U cubesat for ~$100k all in (including launch cost), which puts it in a very different regime.
bilekas 2y ago
If I’m not mistaken there are three on commercial aircraft.. Seems like the bare minimum for a lunar lander .. I can’t imagine they’re THAT heavy
- florbo 2y ago
  Heavier than you think, probably. I tried looking up laser altimeters suitable for moon landings and was met with a much higher than anticipated amount of complexity. One thing was clear: the higher the altimeter needs to work, the heavier.
- adastra22 2y ago
  Every gram of weight is directly trading off payload.

+1 They had the altimeter fail on the previous mission too. Seems like a fairly crucial component of a moon lander. Armchair rocket scientist here, but if I were on that engineering team I'd lobby hard for less science payloads and more backups for critical instruments for the actual flight of the craft. The rover and hopper and drill etc all sound cool yes, but worthless if you can't land. Again. For the second time. Because the same critical component failed, again. With apparently no backup, again. Of course, it sounds so simple. I am sure there is more to it (e.g. perhaps they had backups and everything worked, but they just weren't fit for purpose?)

T-A 2y ago
> They had the altimeter fail on the previous mission too. Not really. They forgot to toggle the safety switch on before launch, so the laser could not be used: https://spaceq.ca/simple-error-could-have-resulted-in-intuitive-machines-mission-failure/ https://spaceq.ca/simple-error-could-have-resulted-in-intuit...

JonChesterfield 2y ago

Had two. One showed so much measurement noise they couldn't trust it, other kept cutting out. Not great.

lionkor 2y ago
So three ones, two different models, one in a different location. These are like... basics, no?
- ricardobeat 2y ago
  If you multiply every critical component by 3x there will be no room left for anything else.
  - lionkor 2y ago
    Well the way they did it (twice) means they had space for other stuff, and of course also failed because they didn't have enough redudancy
  - uoaei 2y ago
    slippery slope fallacy. just do engineering good
  - pclmulqdq 2y ago
    2n + 1 is a basic minimum amount of redundancy for anything critical in a high-value space mission.
    - adastra22 2y ago
      This isn't a high-value space mission.
      - pclmulqdq 2y ago
        The price of a ride to the moon alone would make this "high-value." Cubesats are an example of when you can get away with no redundancy, but this is not a cubesat.
        adastra22 2y ago
        This is best compared to being a lunar landing cubesat. IM is an order of magnitude cheaper than a comparable NASA lander. Cheap is the point, and cheap carries with it some concessions to risk.
        pclmulqdq 2y ago
        $1M was the amount they spent on the lander. If I recall correctly, they got a ride to the moon for free. Delivering that amount of mass to the moon is worth O($10M). It seems incentives were not properly aligned for this group. I should also point out that you can fly a scientific mission on a 1U cubesat for ~$100k all in (including launch cost), which puts it in a very different regime.

bilekas 2y ago

If I’m not mistaken there are three on commercial aircraft.. Seems like the bare minimum for a lunar lander .. I can’t imagine they’re THAT heavy

florbo 2y ago
Heavier than you think, probably. I tried looking up laser altimeters suitable for moon landings and was met with a much higher than anticipated amount of complexity. One thing was clear: the higher the altimeter needs to work, the heavier.
adastra22 2y ago
Every gram of weight is directly trading off payload.