Another Scott Manley comment on the lander design:
Intuitive Machines IM-1 to attempt landing on Feb 22.
- Thread starter Lord Rory Gin
- Start date
Help Support The Rocketry Forum:
Some pictures were downloaded today. As of earlier today lander was still alive.
NTP2
Well-Known Member
Idea! Next time they can put the tanks on top, so by the time they land all the mass is at the bottom and you have a bunch of empty tanks on top.
It seems pretty simple to me or am I missing something.
It seems pretty simple to me or am I missing something.
How do you guarantee the tanks are empty? What if you don't need to use any contingency propellant and you land with a bunch of it still left?
I'm pretty sure they would have done all they reasonably could to lower the CG, regardless.
NTP2
Well-Known Member
that’s a good point, but it leaves me wondering how much contingency they have? Also if that was the max then we are in deep trouble…
- Joined
- Feb 3, 2012
- Messages
- 6,354
- Reaction score
- 5,565
I propose this design...
NTP2
Well-Known Member
Seems a bit aerodynamic for the moon…
But I have a second bad idea, maybe they could have a drop tank, it has the fuel for transfer and deorbit after that it’s dropped and you land with a much lower center of gravity.
You introduce more failure modes by doing that (i.e. the detaching mechanism may not work), and you also have to deal with whatever disruptive reaction force on the lander comes from the tank detachment (Newton's third law).
Not saying any of this is necessarily a showstopper, part of engineering is knowing which risks are and are not worth taking.
NTP2
Well-Known Member
True but I think that 2 landers made by completely different companies both having the same problem means that someone needs to do something to stop it, remember we plan on landing people in a lander with the same basic design (tall and skinny) and we can’t copy the LEM because of size constraints. So we somehow have to make this design work…
Ps I really hate that last sentence, to me it means that we’re doing something very wrong…
terryg
Well-Known Member
Since Starship apparently failed since it did not have a cargo load....
We will see for what they modify for the 2nd lander that they plan on sending at the end of this year. They will have corrected or changed a few things, perhaps have a few different experiments too.
I hope the landing selfie idea gets another crack at it!
IM-1 landed on the moon without any altimeter data, using visual data only.
https://arstechnica.com/space/2024/...landed-on-the-moon-without-any-altimetry-data
https://arstechnica.com/space/2024/...landed-on-the-moon-without-any-altimetry-data
- Joined
- Feb 3, 2012
- Messages
- 6,354
- Reaction score
- 5,565
You would think that they would have an IMU on board and they could use that to confirm their velocity... they could have slowed it down a little early based on the camera and the IMU.
Yeah, good pics - The lander busted 1, maybe 2 landing legs. They say the legs did their job at absorbing the
energy:
energy:
Unfortunately the safety for laser range finder was turned on so the laser was not operative. Having that enabled probably would have provided the necessary information to slow the spacecraft more and land on a more level area. As it was, the alternate distance finding that the lander used meant that the lander came in a little hotter and with more horizontal speed than desired leading to a bit of a bounce & drag of a lander leg upon touchdown. It came down with more force than it was designed to handle. The laser ranger finder was brought up for discussion in today's online update. Somebody forgot to renable it after loading onto the Falcon 9. Something to add to the checklist on IM-2 and IM-3.
I read something similar this morning. The report said that the lander had about a 2 m/s horizontal velocity when it landed.Unfortunately the safety for laser range finder was turned on so the laser was not operative. Having that enabled probably would have provided the necessary information to slow the spacecraft more and land on a more level area. As it was, the alternate distance finding that the lander used meant that the lander came in a little hotter and with more horizontal speed than desired leading to a bit of a bounce & drag of a lander leg upon touchdown. It came down with more force than it was designed to handle. The laser ranger finder was brought up for discussion in today's online update. Somebody forgot to renable it after loading onto the Falcon 9. Something to add to the checklist on IM-2 and IM-3.
As the one scientist said in the above video "it's very hard to land something on the moon."
That supports my idea to make the lander shape less susceptible to tipping. I watched Scott Manley's short video about the current shape of the lander and his opinion was that modifying the lander shape would add too much mass and complication. He obviously knows more about contemporary spacecraft than I do so I can't dismiss what he said. I don't know how difficult it will be to improve the landing guidance of this lander design.
Apparently not that difficult: install the pin to enable the altimeter laser before launch. The only thing wrong with the landing guidance is they couldn't turn it on.
Pretty impressive landing considering it was flying blind and hit the surface when the best available data said it was still 100 meters up.
They had landing guidance, but only optical. It misjudged the altitude, due to not having the laser altimeters functioning, by about 100m. My guess is that without that instrument it couldn't quit pin down its attitude and sideslip accurately, leading to the outcome. It did amazingly well for optical only guidance. Unfortunately it had one too many degrees of freedom without the altimeter.
So as I understand it, while they were able to switch to the NASA experimental lasers for altimetry, the craft couldn't process the data quickly enough? Was it a whole separate laser altimeter or just different lasers? Something in the story didn't stick with me. I thought they had celebrated altimetry worked with the quick patch to NASA lasers.
Last edited:
- Joined
- Jul 23, 2012
- Messages
- 1,899
- Reaction score
- 873
I think they said "the software patch almost worked" but in the end it did not work and did not help. So they landed without their main instrument *and* without their hastily derived alternate instrument.
It's pretty remarkable we're celebrating any landing at all and not just naming a brand new crater.
It's pretty remarkable we're celebrating any landing at all and not just naming a brand new crater.
Whole different instrument, I believe. But they couldn't get it to provide real time data. My understanding is that they started with twelve minute old altimeter data, then computed altitude using inertial and other sensors to plot its movement after that point.
Seems like a good plan, I'm not sure how it ended up a hundred meters off. Maybe the time resolution on the other instruments was too low.
Still pretty amazing they got as close as they did and landed mostly intact.
I could be wrong, but I thought that I had heard that because they were using instruments from the science package and not the intended lasers, that the computers had to process the data in some way before using it and simply couldn't process data fast enough.
That said, I completely understand when they say that the design is tall and skinny because that's a constraint imposed on it by the shroud size. But, while I'm sure that there's a reason this wouldn't work, why not make it even *taller* and then land it sideways on purpose?
NTP2
Well-Known Member
I was going to suggest that then I realized that it would be difficult to make an engine that thrusts in that direction, And tipping it seems like a bad idea.
I was thinking in terms of something that would unfold to be wider and not so tall. Landing sideways could be an improvement because it doesn't have to unfold as much to do that.
MClark
Well-Known Member
Low and wide like it should be.
Lots of available motion to absorb landing shock and slope.
Lots of available motion to absorb landing shock and slope.
