Hacker News Reader

Comment by lionkor | Hacker News Reader

the altimeter? Surely you would put three on there?

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?)

> 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-intuit...

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

So three ones, two different models, one in a different location. These are like... basics, no?

If you multiply every critical component by 3x there will be no room left for anything else.

2n + 1 is a basic minimum amount of redundancy for anything critical in a high-value space mission.

This isn't a high-value space mission.

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.

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.

$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.

Getting to the moon is vastly more expensive. 40x is the multiplier that is typically used in the industry. Prior to cancellation, NASA spent $433M on the VIPER lander + rover--NOT inclusive of launch costs.

$1m is crazy cheap.

$1M is not the full price of this mission. $1M is the price of the lander only. They were given a ride on a rocket whose total bill was $62.5 million (just for the launch, but spread among 4 missions).

When you spend $1 million but get $10 million of stuff for free, it's not really a "$1 million project."

The $433M number I quoted was for the hardware only too. Apples to apples.

I worked NASA planetary science before. $1m is CRAZY cheap.

The first moon landing cost $300 billion+ in today's dollars.

Yeah, this is not that, though. We know how to get to the moon, and a small probe is lighter than 3 people plus a vehicle that allows them to make a return trip.

This launch, which had a few other payloads, too, reportedly cost NASA $62 million.

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

slippery slope fallacy. just do engineering good

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

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.

Every gram of weight is directly trading off payload.

Reply on news.ycombinator.com