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1970-01-01 parent
Still unclear what happened. Did they not anticipate a big moon hole or did navigation fail when the rangefinder failed?
martin_drapeau
Scott Manley has a great video explaining what he thinks happened. https://youtu.be/ISZTTEtHcTg?si=0LZFyiCysBiFZrMz
1970-01-01 OP
Scott Manley and I agree that altitude signal shouldn't matter if navigation is correct. Athena simply risked touchdown, and it didn't find a flat spot, it found a hole.

https://youtu.be/ISZTTEtHcTg&t=1158

ceejayoz
Can you quote the bit you think is relevant here?

He's saying modern spacecraft can null out the horizontal velocity to land, but without an altimeter, you don't necessarily know when to do so, nor when to give the thrusters a little boost to avoid an obstacle you're about to hit, like a plateau.

someothherguyy
Does anyone know an extension that strips this tracking information and normalizes YouTube URLs?
wruza
Just in case, I’m using my own violentmonkey scripts rather than hoping for extensions, and everyone can do that too (now only on firefox, I guess, and maybe brave).

For example, I remove &t=<n> from urls that youtube added recently in addition to regular watch position restoration. This broke it for me and they don’t seem to plan a revert.

Tyr42
That is also used if you want to share a video at a particular timestamp with someone. E.g. check this out it happens 40s in. YouTube.com....&t=40s
wruza
A little downside, yeah, but these scripts can be easily toggled. What can't be easily done is finding my last timestamp in a 5h long vod when &t-in-history screws it up.
numpad0
tldw: speculation: landed with too much lateral velocity and one of legs broke
ceejayoz
I'm not sure what you find unclear. Navigation was fine - "Athena knew where it was relative to the surface of the Moon" - but without a working altimeter it was kinda fucked for actually touching down.

Hard landing, skid, tip.

nomel
> "Athena knew where it was relative to the surface of the Moon" - but without a working altimeter it was kinda fucked for actually touching down.

Z is an axis that exists in our 3d world, and a required value for any relative position, which means it DID NOT know where it was, relative to the moon.

PantaloonFlames
Ya the wording was not quite … satisfactory. I think they meant , it could tell X and Y, but not Z.

But all three are important.

Related - I’m not clear how the article can describe that landing as “not crashing”. If that was not a crash, what was it? Will they call it a crash only if there are Hollywood-style explosions?

jacobgkau
Bringing "Hollywood-style explosions" into it is a little much. If you slam the breaks on in your car, your tires hit some debris in the road, and you spin around and end up somewhere you didn't intend to be, but the car wasn't meaningfully damaged (i.e. you didn't hit other cars or manmade structures), you made a dangerous uncontrolled maneuver, but you didn't crash. That seems more like how they're describing this "skid."

Relevantly, it sounds like this lunar spacecraft was still functioning after the hard (non-)landing. The only reason it died after that was because of debris settling on the solar panels, which made it run out of power.

PhasmaFelis
If you do something with your car that ends up with it skidding on its side, that's a crash by any possible definition.
jacobgkau
Probably, but this is a space probe, not a car. It's lighter than a car, and is operating in an environment with less gravity.
Retric
One of the legs broke off which requires significant forces not just a skid.

I mean if my car lands on the side and one of it’s wheels fell off that’s a significant crash.

jacobgkau
The leg breaking off is probably the best supporting evidence towards calling it a crash, I'll agree with that.
rdiddly
"The only reason?" One reason for prematurely losing most of the investment is enough. The car analogy is inadequate but let's say my car skids gently into a position from which it won't start and I can't get out and I slowly die of starvation and/or hypothermia. Am I glad that I didn't "crash?"
jacobgkau
I didn't say the mission was a success. I was addressing someone's nitpick over the definition of the word "crash."

If the space probe had a wiring failure after landing that caused the loss of "investment," that wouldn't be a crash. It would be a separate problem.

meindnoch
But if they knew where it was relative to the surface of the Moon, they could have subtracted that from where it wasn't, or where it wasn't from where it was (whichever is greater), to obtain a difference, or deviation. The guidance subsystem could then use deviations to generate corrective commands to drive the missile from a position where it was to a position where it wasn't.
JshWright
The top-heavy design didn't help things either. I'll be shocked if they don't go three-for-three on landing sideways given IM3 has the same tall design.
ceejayoz
The company claims it's not as top-heavy as you'd think from pics:

https://www.theregister.com/2025/03/07/intuitive_machines_la...

> At his press conference earlier today, Altemus defended the design, saying the spacecraft doesn’t have a high center of gravity because most of its cargo attaches to the base of the vehicle. He said there were no plans for a radical rethink of his company's design.

(We see this in returning F9 first stages, as well.)

sandworm101
>> The top-heavy design didn't help things either

Just wait for SpaceX to start trying to land starships on the moon. Also vertically. Also doomed to tip over whenever the surface is slightly out of spec.

https://www.spacex.com/humanspaceflight/moon/

oceanplexian
Why does this even have to be a problem?

We can send small probes to image the moon in incredibly high resolution. It's a big place I'm sure there is a perfectly flat rock somewhere they can use.

sandworm101
Have you ever seen a perfectly flat rock anywhere on earth? One capable of supporting a large rocket? Also, the moon doesn't have the various navigation systems (GPS/radar) that is used when bringing rocket stages back the pad.
JumpCrisscross
> Just wait for SpaceX to start trying to land starships on the moon. Also vertically

SpaceX has done it. To date, other nation-states have tried and failed to replicate their achievements in this domain.

IM’s design is wrongly optimised and probably requires a rethink. That the CEO won’t contemplate this isn’t a great sign for the company.

CamperBob2
SpaceX has done it.

SpaceX has landed Starship on the moon?!

9 More Comments →
sandworm101
Lol. SpaceX has landed on prepared surfaces, concrete pads on land or on large barges. They literally have a big X to mark the target. Let's see them land on some random beach, an uneven surface that may or may not subside. But that is still peanuts comparted to the moon's surface.
9 More Comments →
Frederation
Keep that Musk copium going, man!
tekla
Why do people keep thinking this thing is top heavy just because its taller than wide?

The heavy bits are at the bottom.

timmg
> Why do people keep thinking this thing is top heavy just because its taller than wide?

Because it keeps falling over?

tekla
The landing leg broke. How does that show you its top heavy?
3 More Comments →
_bin_
i think this becomes somewhat less of an issue once SpaceX gets Starship fulfilling contracts at scale. they're limited in width by the max payload faring width for Falcon 9, which is like half that of starship. add to that an exec claimed it's tall but not necessarily top-heavy as mass isn't evenly distributed throughout.
strangattractor
Or use New Glenn which works now and has a larger faring.
walrus01
Was there no functioning laser or radar altimeter for the final descent phase?
ceejayoz
"However, the lander's altimeter had failed."
1970-01-01 OP
Looking at this closely, it was working, however it was noisy. I speculate that they didn't correctly anticipate the moon dust problem. Laser rangefinders may not be a workable solution for future landings.

     So engineers at Intuitive Machines had checked, and re-checked, the laser-based altimeters on Athena. When the lander got down within about 30 km of the lunar surface, they tested the rangefinders again. Worryingly, there was some noise in the readings as the laser bounced off the Moon. However, the engineers had reason to believe that, maybe, the readings would improve as the spacecraft got nearer to the surface.
https://arstechnica.com/space/2025/03/intuitive-machines-sec...

https://www.space.com/nasa-moon-landing-dust-concerns.html

https://en.wikipedia.org/wiki/Lunar_horizon_glow

ceejayoz
Noise at 30km altitude probably points more towards a sensor issue than dust.
4 More Comments →
numpad0
LRFs and radars on the Moon has been fine for a long time, it can also be angled away from gravity axis and multiplied by sine theta if needed.
1970-01-01 OP
If navigation was fine, why was touchdown on a plateau?
ceejayoz
Because "where am I" and "how high am I over that position" are very different things.

Visual demonstration of being at the wrong altitude in the right spot: https://www.f-16.net/f-16-news-article968.html

echoangle
If you don’t know your altitude, navigation isn’t fine though. Navigation should give you a position in all axes.
russdill
It touched down with a large horizontal velocity component
PantaloonFlames
That’s another thing that bothered me about this story. They said they knew where the craft was , relative to the surface of the moon. Wouldn’t that also mean they should know of any substantial horizontal (x/y) component of velocity?
marcosdumay
I don't know if it's the case, but there's a difference between knowing something and calculating its derivative fast enough for it to be useful.
gtirloni
Yes, through image analysis.

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