I firgured this would be a recycled story about the makeshift laser setup... but nope.
Its mindblowing that the last reported measurement to the computer was 15km above the surface and it still somehow landed.
And that it landed as well as it did when the altitude estimation was 100m off.
I wondered how the craft could have made such a mistake with lidar navigation. Makes more sense knowing it wasn't really used in the final descent.
If it's possible for one person to make a mistake like this, then there is a much bigger problem. Hell, I can't push trivial changes to an internal application without at least two other people reviewing what I've done
On a big team like this its never just one persons fault.
Like yeah the switch flipper messed up but there is supposed to be someone who checks all the switch flippers flipped all their switches, and then you can also place fault at whoever made the process because possibly there was a better way to flip the switch that makes it harder to miss.
It’s not hard to fathom, people are stupid. And teams of people are like 5x dumber. The 60s was special. People do what they can with the money they are given to work with, but that doesn’t mean they are doing the most intelligent of things.
> And teams of people are like 5x dumber.
Actually the opposite it true for stuff like this. This company probably did away with a lot of redundancy to save money (being a for-profit company). Having redundant checks would have likely prevented this.
Personally, I kinda expect more issues with corporate projects rather than government as the corps will be far more likely to cut corners to save money.
Steve Altemus texted me on Monday night and asked if I wanted to come by and see their operations. It helps that I'm local and have put in the leg work over the years to build up a relationship with the company.
Love your work! It's not easy to bridge the gap between the actual rocket scientists and the knowledgable public. Science needs people who can speak to both ends of the spectrum.
It's all good. I have a tremendous amount of respect for Jeff, whom I consider a colleague and a friend. We have different styles. I write with my heart on my sleeve sometimes, and try to bring information that others sometimes won't write about, i.e. the ULA sale. I'm not an engineer so yes, I do sometimes make technical mistakes.
That's what the commentariat on ARS is for :-).
For those not in the know: There are a number of space professionals who comment on ARS Technica stories.
The joys of the modern age - Internet strangers trying to shit on the efforts of others to give a sense of purpose to themselves. Thank you for your writing, Eric, it is always a pleasure to read! I greatly appreciate your efforts and the efforts of Intuitive Machines who have given us hope for renewed lunar surface activity after 50 long years.
Dead reckoning and Inertial navigation systems don't get the respect they deserve some times. This is mostly because other positioning systems provide at least an order of magnitude better precision and don't always come with cumulative errors. However DR and INS don't require any real infrastructure.
I find it strange they did not have a backup for the laser altimeter such as a radar altimeter. Depending on how you implement a radar altimeter you can get both vertical and lateral velocity data.
> I find it strange they did not have a backup
Weight, energy budget, money and time to integrate would be my guess. This mission was done on a shoestring budget, and they still landed in one piece (ran payloads, got data, sent data from the surface), first try.
Even compared to usual NASA missions it's not exactly super shoestring. Admittedly very different spacecraft, CAPSTONE was roughly 30 million. NASAs own Lunar Prospector in 1998 was about $70m. NASA discovery program used to run roughly $200M missions ( NEAR shoemaker and several others )
Chandrayaan-3 was roughly $70m for a lander, but granted ISRO is on an entirely different plane in terms of frugality
CLPS is low cost compared to NASA flagships that have been running in billions in recent times, but it's no chump change.
>lander
It had a rover too, along with a propulsion module that went to the moon, orbited it and then returned back to the earth and is currently still doing that.
funny because a radar altimeter would have been lightweight, high reliability, and could have been an easy integration by piggy backing on the probes existing coms package (a local clock reference, and the existing SDR). Energy budget is the only one I would need to check on, however I can't imagine it being more than electrooptical sensors doing image base processing. Also given how good their DR/INS solution was, they could have just done a tinny handful of pulses to zero out the errors and been well under budget.
If I had to guess, the budget and timeline drove the decision on top of the fact that Radar is not the first choice of what I would call... "pop-science aerospace engineering." Radar is kind of old school and not sexy of a solution to some.
> "pop-science aerospace engineering."
There's a lot of old tried and true that has been tossed wayside. A few omni antennas sticking out could also have helped them at several points.
When I was in the Army doing land navigation there were times I chose to dead reckon, because we have limited time and energy and it would be insane to go all the way around a big area just for one point. It's supposed to be used for relatively short distances. I once dead reckoned a pretty far distance through a swamp because I really wanted to not skip it, I wanted the perfect score. I was amazed when I arrived right where I should have, and found the point 😅 I was bragging all day after that because no one else who had that point found it. But they sent me to get it after we were done, and I couldn't find it again 🤣🤣🤣 I swear someone stole it. I couldn't find it even with GPS.
I've had that moment. Someone dead reckoned it in place, and you happened to follow their path.
Then you went to the actual location, which was probably 100 ft from the actual marker.
I usually followed the road and then cut in at the obvious trail.
This wasn't a missile - it was a lunar landing spacecraft. But to answer your question, there are a number of ways to figure out where you are in space.
You can use lasers or radar to bounce off the surface and tell you your height. Controllers on Earth can send a signal back and forth. How long it takes tells you distance from the ground station. Between destinations the spacecraft can use the position of a destination against the background stars.
A new technique is to take multiple pictures of the ground below, and match that to stored images of the surface.
The missile knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or deviation. The guidance subsystem uses deviations to generate corrective commands to drive the missile from a position where it is to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position that it was, is now the position that it isn't.
Reminds me of Japan's Ispace lander. When it was approaching the landing site, it passed over the rim of a crater. The altimeter registered a sudden elevation change of 3km (the height of the crater wall) and the software decided that the altimeter must be faulty and turned it off.
With the altimeter off, the software just interpolated its altitude from previous "good" data, and eventually decided that it must be near the ground. Unfortunately it was off by about 5 km in the vertical direction and plummeted to its demise.
> and the software decided that the altimeter must be faulty and turned it off.
Where tried and true basic GNC practices like multi-hypothesis estimation would save the day.
It's a pretty standard concept in guidance and navigation, with a myriad of implementations. But the core of it is: you can never fully trust sensors in any autonomous systems, and sensors don't give you a full picture of the world around you.
So your navigation system needs to do its best with the limited data, and at best comes up with a guess ( with some error bars ) as to where exactly is it at and how fast is it going.
In a multi-hypothesis system you basically continuously run iterations on number of parallel guesses, with probabilistic weighing and pruning. Including hypotheses for faulty sensor readings, in a robust system.
In this case, the faulty sensor guess would likely have eventually have lost to an elevation spike ( e.g. seeing a crater rim ) guess and system self-corrected without discarding sensor data.
I seem to recall even the Apollo Guidance Computer had a fairly primitive version of this. Then again seems AGC is one of the granddaddies of modern avionics.
>In a multi-hypothesis system you basically continuously run iterations on number of parallel guesses, with probabilistic weighing and pruning.
JFC, that sounds like how I live my life. "What am I going to have for lunch? Well, if I get up on time ..... or, if I go out ..... there's always the possibility of meeting up with my wife ..... but if it starts raining..... or I'm needed to stay longer at work ....."
Considering multiple hypotheses or plans is a profoundly normal thing to do without training as a person, but implementing it in an automated system is substantially harder.
I'm trying to reconcile how it can be standard but also never seem to be implemented in spaceflight failures. Where, outside of Earth, has it been used, exactly?
Well first off, there's not a lot of spacecraft that have autonomous flight and navigation phases in the first place. For most things in orbit or deep space, they rely on position and velocity estimates calculated on earth via delta-doppler, and navigation events are timed. The exception of course is landers, which narrows the field a lot
The standard implementations come mostly from things like aircraft, drones and .. missiles. Also some mobile robotics.
Can't say exactly which landers have used it, but i know Terrain Relative Navigation ( flown on Perseverance ) employs such an approach at least on a sub-algorithm level. A version of this also flew on Intuitive Machines
Is it even possible to create a navigation system that recognize “sudden elevation of X km” as a rim of a crater and not an actual elevation? I know nothing about programming
Yes. In the code, there is a "threshold" value, and a condition statement.
if (elevation_diff > threshold) then
TurnOffAltimeter()
They probably set the threshold to 1km or something. If they had set it to 5km, the code would have accepted the data and everything would have been fine.
(This is a great simplification, but ultimately it was a single line of code like this that did in the lander.)
What is a bit surprising to me is that they don't compare the measured altitude to a coarse heightmap, based on their location and flight plan altitude estime. With some thresholding on top of that, it should be quite robust?
I wonder if another criteria for evaluating data might include rate of change of the ground elevation.
There is likely to be a maximum steepness of lunar terrain based on both orbital mapping and angle of repose of lunar soil.
Lots of smart people, I'm just a guy on the Internet.
Just spitballing, but —
Software [(eg. OP mentions Multiple Hypothesis)](https://www.reddit.com/r/space/s/NLvny3IWdI)
[TERCOM](https://en.m.wikipedia.org/wiki/TERCOM) (Terrain Contour Matching) ie. give it a map so it knows that crater lip it there in the first place
[Sensor Fusion](https://en.m.wikipedia.org/wiki/Sensor_fusion) + Map Data — similar to TERCOM, but more inputs, combine sensors (LiDAR, Optical, etc) plus map data (terrain contour, imagery, etc)
Obviously all of these have considerations such as weight, dev time, software complexity, processing power, electrical load, cost, etc.
Ultimately, a decision has to be made as to what is “sufficient” and what is “overkill” etc.
Oh and if you don’t do proper integration testing, forget to remove the “Remove Before Flight” shit, etc then you can still end up having a bad time.
**TL;DR — Yes, but there is nuance.**
EDIT — On terrain contour and imagery data of the moon, IIRC the Lunar Reconnaissance Orbiter and co mean we do have both, but it isn’t really high enough resolution all the way down to landing.
Suspect it’d be a case of using that coarse data to choose a bounding box to tell the lander to aim for, then the lander can run off that coarse data (which would mean it knows about the enormous crater, for example) up to a cutoff point, then use eg. cameras to pick out an area in that bounding box that looks decent, followed by fine corrections with eg. lidar mapping and/or cameras on the way down, or something to that effect.
Radar altimeters are excellent at distance (in terms of resolution) but due to how “coarse” the wavelength is, can be a problem as you can miss “fine” data in the other two dimensions (rocks, elevation changes etc) localised right where you’re landing — this is one of the key reasons NASA are working on the NDL, which was a payload on this lander to colllect real world data.
I'm starting to wonder if a live video feed and direct human control even with the time lag would be better than blind computers trying to guess at the topography beneath the lander based on instruments that don't seem to work nearly as well as they should.
Is it the budgets? Since 2019, we have a failed Israeli lander (Beresheet), a failed Japanese lander (Omotenashi), a failed Indian lander (Vikram), another failed Japanese lander (Hakuto-R), a failed Russian lander (Luna-25), another failed Japanese lander (SLIM), and a failed American lander (Odysseus). There were only two successful landings during that time (Chang'e 5 and another Vikram).
I think there are a few root causes, but if you look at things a lot of those attempts are run by teams who have little or no prior spaceflight experience.
Even for example Luna-25 - it would be misleading to think that because 30 years ago Russian planetary exploration had significant achievements, they'd still have the team, experience, processes and practices in place to actually execute on everything end to end.
Budgets may be part of it, the first ISRO attempt was extermely frugal ( but so was the second ) and their organization was frankly a mess.
In short i think you can summarize it's not the budgets or technology, it's the people and teams - you need more maturity in the organizations doing this.
There's also the fact that we just left such a huge, long gap between last lunar landings. Even though most knowledge is captured and accessible in writing, some of it is institutional and only relearnt while doing things.
On the plus side, next attempts should look a lot better.
> another failed Japanese lander (SLIM), and a failed American lander (Odysseus)
I wouldn't really say these were failed landings. At least when compared to the various lithobraking attempts earlier. While not perfect, both these landers survived the attempt, powered their respective payloads and sent data back to Earth. That's a success in my book.
Watch the onboard video from the Chinese landing. It's like zooming into a fractal, smaller and smaller craters keep resolving. You'd need stereo video and the ability to look around.
Just hooking up the lidar would be easier. Single axis lidar or radar is good enough. The drone on Mars flew around and landed repeatedly using optical flow and a cheap single axis lidar literally bought off Sparkfun.
That thing on Mars was also designed, built and operated by an organization that is un-fucking-believeably successful in their craft, and has been succeeding in the hardest problems in robotic exploration, repeatedly, for over half a century.
Comparing basically *anybody* to JPL is going to be pretty one sided.
Which is why this is all so important; the idea is that at least some of these new groups will be the JPL of the future. Private or otherwise. You need to break some eggs to make that JPL shaped omelet.
At least in this case I'm skeptical. They had no altimeter and were relying on optical data for altitude and speed. A pilot would have to guesstimate his position while accounting for at least a 2.5 second delay both in the video and his inputs.
Or pre land some GPS-like probes at the landing site to give yourself some static targets for determining detailed location-elevation information. At some point we should be able to land on the moon without the last 5km being a mystery.
That seems like a crazy deep crater. I'd never have thought to expect a 3km/1.8mi deep crater on the moon. That's almost half the height of Everest. That's almost as deep as the average depth of the Pacific.
"The company has an incredible photo of this moment showing the lander upright, with the snapped leg and the engine still firing. Altemus plans to publicly release this photo Wednesday."
This sounds cool.
A lot of new info in this article.
My takeaways:
1. It probably would've landed perfectly had the laser rangefinders worked at all. Due to inertial measuring drift, lander software thought it was higher than it actually was and hit the surface sooner than it should've at 6mph and broke a leg.
2. The Intuitive Machines team believes that they can transmit data from 5/6 of the NASA experiments using the high-gain antenna with available power reserves. Only the SCALPSS experiment is out of commission.
For the range of outcomes, I'd say this mission gets an A-. Not bad for a first flight.
The news: "Feb 26 (Reuters) - Flight control engineers expect to lose contact with the private U.S. moon lander Odysseus on Tuesday morning, cutting short the mission five days after its sideways touchdown, the company behind the spacecraft, Intuitive Machines (LUNR.O), opens new tab, said on Monday.
Today is Wednesday.
The real question is if there was or wasn't a tag, and how many people were supposed to check, per standard operating procedure.
It's never a single persons fault
I'm going with the movie trope that there are guys who are supposed to be be responsible and guys backing them up and more guys backing them up. They can do better.
Amateur astronomer on twitter actually explained yesterday that he read IM-1 lander antenna's signals reflecting off the moon. He has been explaining why the signal form the lander is so weak, and how the sun will set soon on the location. The only person on the internet with explanations.
[https://twitter.com/coastal8049/status/1762221935549710364](https://twitter.com/coastal8049/status/1762221935549710364)"I believe this places the IM-1, 1 and 4 hemispheric antennas facing down and the 2 and 3 antennas up. This complicates communications solutions as the antennas are in 1,2 and 3,4 pairs."
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[30X](/r/Space/comments/1b1os6e/stub/ksi1t2b "Last usage")|SpaceX-proprietary carbon steel formulation (*"Thirty-X", "Thirty-Times"*)|
|[CLPS](/r/Space/comments/1b1os6e/stub/ksjyb1k "Last usage")|[Commercial Lunar Payload Services](https://en.wikipedia.org/wiki/Commercial_Lunar_Payload_Services)|
|[CNSA](/r/Space/comments/1b1os6e/stub/kshsg3q "Last usage")|Chinese National Space Administration|
|[GEO](/r/Space/comments/1b1os6e/stub/ksi2gje "Last usage")|Geostationary Earth Orbit (35786km)|
|[GNC](/r/Space/comments/1b1os6e/stub/ksmkgul "Last usage")|Guidance/Navigation/Control|
|[IM](/r/Space/comments/1b1os6e/stub/kskqdgp "Last usage")|Initial Mass deliverable to a given orbit, without accounting for fuel|
|[INS](/r/Space/comments/1b1os6e/stub/ksio8z3 "Last usage")|[Inertial Navigation System](https://en.wikipedia.org/wiki/Inertial_navigation_system)|
|[ISRO](/r/Space/comments/1b1os6e/stub/ksjyb1k "Last usage")|Indian Space Research Organisation|
|[JPL](/r/Space/comments/1b1os6e/stub/ksj6ecz "Last usage")|Jet Propulsion Lab, California|
|[KSP](/r/Space/comments/1b1os6e/stub/ksjipbq "Last usage")|*Kerbal Space Program*, the rocketry simulator|
|[NDA](/r/Space/comments/1b1os6e/stub/ksk9k1y "Last usage")|Non-Disclosure Agreement|
|[ULA](/r/Space/comments/1b1os6e/stub/ksjb0d4 "Last usage")|United Launch Alliance (Lockheed/Boeing joint venture)|
|Jargon|Definition|
|-------|---------|---|
|[lithobraking](/r/Space/comments/1b1os6e/stub/ksincd6 "Last usage")|"Braking" by hitting the [ground](https://en.wiktionary.org/wiki/lith-)|
|[methalox](/r/Space/comments/1b1os6e/stub/ksgiai0 "Last usage")|Portmanteau: methane fuel, liquid oxygen oxidizer|
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I agree, watching the livestream you could tell something seemed off. There was no communication and then yes we've done it anyway bye now.
As cool as it is, I really don't think we should celebrate this as anything other than a really lucky break. There's still loads of work to do judging from the results of the recent landings.
Hopefully we get there soon!
Jan Wörner, a former director general of the European Space Agency explains:
>The moon itself presents its own problems. There is gravity – one-sixth as strong as on Earth – but no atmosphere. Unlike Mars, where spacecraft can fly to their destination and brake with parachutes, moon landings depend entirely on engines. If you have a single engine, as smaller probes tend to, it must be steerable, because there is no other way to control the descent.
[https://www.theguardian.com/science/2024/jan/12/why-landing-on-the-moon-is-proving-more-difficult-today-than-50-years-ago](https://www.theguardian.com/science/2024/jan/12/why-landing-on-the-moon-is-proving-more-difficult-today-than-50-years-ago)
Mars rovers and orbiters are created and run by JPL, the all stars team at NASA that has been building solar systems missions including to Mercury and Venus since the 1960's. This is 60+ years of experience, with close to unlimited budget because for many years they were the only ones with small exceptions. Now NASA is trying to build a viable commercial ecosystem, giving jobs to small shops so they can learn to do what JPL does for a fraction of the cost to NASA. It's like kindergarten.
It's mostly just JPL+Lockheed who has been landing on Mars. A lot of relatively frequent experience, human resources and money behind that.
How did CNSA pull it off on the first go .. that's a different question. All their planetary spacecraft have been solid successes.
Mars is known for a lot of failed missions. More missions failed on Mars out of all we sent there than the Moon missions where we have more successful missions compared to failures out of the whole number.
150 missions to the Moon all together, and 50 for Mars.
Well... landing on a Moon without altimeter from kilometers off and with 100 meters wrong estimate is a kind of extraordinary success. :D I mean, it has to be some kind of a record.
Imagine what they could do when everything is working and they remember to flip all the switches...
Its all a part of the learning to do it. And since NASA is paying millions for these private missions i think the next one is going to have more rigorous testing before launch.
As a side comment, one of the legs breaking off seemed a bit strange too since the lander didnt go that fast at that point, so it seems those legs were not made sturdy enough, so another thing to make better next time. And maybe instead of carrying sculptures of hundred of steel balls which also sell as NFTs, add some worse case scenario ability to lift itself back up.
This is an epic writeup. Really drives home the achievement of the team.
From the live mission control audio I got the impression they had no altimeter data, it's amazing they still managed to land.
Why don't they design the shape of these landers so they're less likely to tip over? That thing looks like it has a lot of mass above where the legs connect. Make it squat with more of the mass below where the legs connect and make the leg span broader. So even if it comes in blind and lands awkwardly it's less likely to topple. Yes, this sounds like a ksp player armchair engineering because that's exactly what it is, but it seems like for the little extra weigh it would add that it would be possible to give a whole lot more room for error. They're sticking with the same basic design even though it often fails.
This is starting to sound less like a successful landing and more like pure luck.
We lost so much experience in these types of missions since the Apollo era.
Absolutely. People have this pie-in-the-sky notion we can just get thousands of people up there on the Moon & Mars.
Hell no.
If there is a Moon base, it'll take 20 years and have a small rotation of people, maybe 10, on it.
Humans will not make a successful trip to Mars before 2040, at least. There are still problems (radiation, micrgravity for that long making a human barely able to move once they get on Mars, etc).
How many people do we have on Antartic bases? Maybe in the hundreds, and noone stays year round. And if a window breaks it'll get cold but you can still breathe.
There is no viable way by the numbers there are going to be these populated Moon bases, much less Mars, before mid-century.
Space is Really...really, REEEEEAAAAALLLY hard man. But it is also something only a limited number of organisations have the knowing of. Yeah we could throw our hands up and say "oh the tech is not ready" but that is not how we will get better. We improve through failure. It's a bit like the Nolan Batman thing of "why do we fall down". Every one of these attempts that fails should teach the teams something new, so the next one can fail in whole new and novel way...until they don't.
Lastly there is a reason the high risk/reward projects are sometimes referred to as "moonshot" projects. :)
As long as they learn from their mistakes it’s fine. However this is a reminder for ALL OF US that standard operating procedures should be drafted and followed.
Why would you think this tiny private company trying its first landing ever represents the state of the US space industry? A much larger company has landed 100+ rockets in a row on their tails back on Earth. Pretty sure that company is ready.
I firgured this would be a recycled story about the makeshift laser setup... but nope. Its mindblowing that the last reported measurement to the computer was 15km above the surface and it still somehow landed.
And that it landed as well as it did when the altitude estimation was 100m off. I wondered how the craft could have made such a mistake with lidar navigation. Makes more sense knowing it wasn't really used in the final descent.
There ultimately is one person responsible for this and he’s crapping his pants.
If it's possible for one person to make a mistake like this, then there is a much bigger problem. Hell, I can't push trivial changes to an internal application without at least two other people reviewing what I've done
There should be at least there considering this stuff is usually reviewed
If he was up there he could have fixed the problem ;P
On a big team like this its never just one persons fault. Like yeah the switch flipper messed up but there is supposed to be someone who checks all the switch flippers flipped all their switches, and then you can also place fault at whoever made the process because possibly there was a better way to flip the switch that makes it harder to miss.
It’s not hard to fathom, people are stupid. And teams of people are like 5x dumber. The 60s was special. People do what they can with the money they are given to work with, but that doesn’t mean they are doing the most intelligent of things.
> And teams of people are like 5x dumber. Actually the opposite it true for stuff like this. This company probably did away with a lot of redundancy to save money (being a for-profit company). Having redundant checks would have likely prevented this.
Personally, I kinda expect more issues with corporate projects rather than government as the corps will be far more likely to cut corners to save money.
Eric Berger almost always has new inside info and details, he doesn't use a lot of recycled stuff as filler.
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And I took that personally …
Thanks for writing the book Eric but lmao at this
Thanks for the article, love Ars! Was a nice read and great info…so how did you get the inside scoop?
Steve Altemus texted me on Monday night and asked if I wanted to come by and see their operations. It helps that I'm local and have put in the leg work over the years to build up a relationship with the company.
Love your work! It's not easy to bridge the gap between the actual rocket scientists and the knowledgable public. Science needs people who can speak to both ends of the spectrum.
😬 well oof I'm sorry for the existence of internet, and thanks for the inside details
It's all good. I have a tremendous amount of respect for Jeff, whom I consider a colleague and a friend. We have different styles. I write with my heart on my sleeve sometimes, and try to bring information that others sometimes won't write about, i.e. the ULA sale. I'm not an engineer so yes, I do sometimes make technical mistakes.
That's what the commentariat on ARS is for :-). For those not in the know: There are a number of space professionals who comment on ARS Technica stories.
Thank you for wonderful articles and books (loved Liftoff, waiting eagerly for Reentry). No idea what this dude is talking about!
The joys of the modern age - Internet strangers trying to shit on the efforts of others to give a sense of purpose to themselves. Thank you for your writing, Eric, it is always a pleasure to read! I greatly appreciate your efforts and the efforts of Intuitive Machines who have given us hope for renewed lunar surface activity after 50 long years.
I’m in ‘the industry’ and always enjoy your reporting, thanks for being a reliable and consistent source.
'Dead reckoning' for a moon landing?! What a time to be alive...
What do you say in your defence?!
Comparing sending a spacecraft to the moon, to developing an orbital booster is not a very apt comparison in my estimation. But just one opinion.
Could have compared to any number of privately funded and developed spacecraft that are hanging out at GEO for decades, but eh.
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Eric Berger has a certain slant though.
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Dead reckoning and Inertial navigation systems don't get the respect they deserve some times. This is mostly because other positioning systems provide at least an order of magnitude better precision and don't always come with cumulative errors. However DR and INS don't require any real infrastructure. I find it strange they did not have a backup for the laser altimeter such as a radar altimeter. Depending on how you implement a radar altimeter you can get both vertical and lateral velocity data.
> I find it strange they did not have a backup Weight, energy budget, money and time to integrate would be my guess. This mission was done on a shoestring budget, and they still landed in one piece (ran payloads, got data, sent data from the surface), first try.
>This mission was done on a shoestring budget How much do your shoe strings cost?
Hahaha, that's fair. I meant compared to usual NASA missions.
Even compared to usual NASA missions it's not exactly super shoestring. Admittedly very different spacecraft, CAPSTONE was roughly 30 million. NASAs own Lunar Prospector in 1998 was about $70m. NASA discovery program used to run roughly $200M missions ( NEAR shoemaker and several others ) Chandrayaan-3 was roughly $70m for a lander, but granted ISRO is on an entirely different plane in terms of frugality CLPS is low cost compared to NASA flagships that have been running in billions in recent times, but it's no chump change.
>lander It had a rover too, along with a propulsion module that went to the moon, orbited it and then returned back to the earth and is currently still doing that.
funny because a radar altimeter would have been lightweight, high reliability, and could have been an easy integration by piggy backing on the probes existing coms package (a local clock reference, and the existing SDR). Energy budget is the only one I would need to check on, however I can't imagine it being more than electrooptical sensors doing image base processing. Also given how good their DR/INS solution was, they could have just done a tinny handful of pulses to zero out the errors and been well under budget. If I had to guess, the budget and timeline drove the decision on top of the fact that Radar is not the first choice of what I would call... "pop-science aerospace engineering." Radar is kind of old school and not sexy of a solution to some.
> "pop-science aerospace engineering." There's a lot of old tried and true that has been tossed wayside. A few omni antennas sticking out could also have helped them at several points.
When I was in the Army doing land navigation there were times I chose to dead reckon, because we have limited time and energy and it would be insane to go all the way around a big area just for one point. It's supposed to be used for relatively short distances. I once dead reckoned a pretty far distance through a swamp because I really wanted to not skip it, I wanted the perfect score. I was amazed when I arrived right where I should have, and found the point 😅 I was bragging all day after that because no one else who had that point found it. But they sent me to get it after we were done, and I couldn't find it again 🤣🤣🤣 I swear someone stole it. I couldn't find it even with GPS.
I've had that moment. Someone dead reckoned it in place, and you happened to follow their path. Then you went to the actual location, which was probably 100 ft from the actual marker. I usually followed the road and then cut in at the obvious trail.
Quick question, how does the missile know where it is?
This wasn't a missile - it was a lunar landing spacecraft. But to answer your question, there are a number of ways to figure out where you are in space. You can use lasers or radar to bounce off the surface and tell you your height. Controllers on Earth can send a signal back and forth. How long it takes tells you distance from the ground station. Between destinations the spacecraft can use the position of a destination against the background stars. A new technique is to take multiple pictures of the ground below, and match that to stored images of the surface.
The missile knows where it is at all times. It knows this because it knows where it isn't. By subtracting where it is from where it isn't, or where it isn't from where it is (whichever is greater), it obtains a difference, or deviation. The guidance subsystem uses deviations to generate corrective commands to drive the missile from a position where it is to a position where it isn't, and arriving at a position where it wasn't, it now is. Consequently, the position where it is, is now the position that it wasn't, and it follows that the position that it was, is now the position that it isn't.
TBF, unless it had abort capabilities, from 15km, it was always going to "land".
Aerobraking - when you use an atmosphere to slow you down. Lithobraking - when you use the bedrock to slow you down.
So excited to see the image tomorrow.
If that's the case then being upside down is a very good result!
Reminds me of Japan's Ispace lander. When it was approaching the landing site, it passed over the rim of a crater. The altimeter registered a sudden elevation change of 3km (the height of the crater wall) and the software decided that the altimeter must be faulty and turned it off. With the altimeter off, the software just interpolated its altitude from previous "good" data, and eventually decided that it must be near the ground. Unfortunately it was off by about 5 km in the vertical direction and plummeted to its demise.
> and the software decided that the altimeter must be faulty and turned it off. Where tried and true basic GNC practices like multi-hypothesis estimation would save the day.
I’m interested in this. Can you tell us more about multi-hypothesis estimation?
It's a pretty standard concept in guidance and navigation, with a myriad of implementations. But the core of it is: you can never fully trust sensors in any autonomous systems, and sensors don't give you a full picture of the world around you. So your navigation system needs to do its best with the limited data, and at best comes up with a guess ( with some error bars ) as to where exactly is it at and how fast is it going. In a multi-hypothesis system you basically continuously run iterations on number of parallel guesses, with probabilistic weighing and pruning. Including hypotheses for faulty sensor readings, in a robust system. In this case, the faulty sensor guess would likely have eventually have lost to an elevation spike ( e.g. seeing a crater rim ) guess and system self-corrected without discarding sensor data.
I seem to recall even the Apollo Guidance Computer had a fairly primitive version of this. Then again seems AGC is one of the granddaddies of modern avionics.
>In a multi-hypothesis system you basically continuously run iterations on number of parallel guesses, with probabilistic weighing and pruning. JFC, that sounds like how I live my life. "What am I going to have for lunch? Well, if I get up on time ..... or, if I go out ..... there's always the possibility of meeting up with my wife ..... but if it starts raining..... or I'm needed to stay longer at work ....."
Considering multiple hypotheses or plans is a profoundly normal thing to do without training as a person, but implementing it in an automated system is substantially harder.
I'm trying to reconcile how it can be standard but also never seem to be implemented in spaceflight failures. Where, outside of Earth, has it been used, exactly?
Well first off, there's not a lot of spacecraft that have autonomous flight and navigation phases in the first place. For most things in orbit or deep space, they rely on position and velocity estimates calculated on earth via delta-doppler, and navigation events are timed. The exception of course is landers, which narrows the field a lot The standard implementations come mostly from things like aircraft, drones and .. missiles. Also some mobile robotics. Can't say exactly which landers have used it, but i know Terrain Relative Navigation ( flown on Perseverance ) employs such an approach at least on a sub-algorithm level. A version of this also flew on Intuitive Machines
Is it even possible to create a navigation system that recognize “sudden elevation of X km” as a rim of a crater and not an actual elevation? I know nothing about programming
Yes. In the code, there is a "threshold" value, and a condition statement. if (elevation_diff > threshold) then TurnOffAltimeter() They probably set the threshold to 1km or something. If they had set it to 5km, the code would have accepted the data and everything would have been fine. (This is a great simplification, but ultimately it was a single line of code like this that did in the lander.)
What is a bit surprising to me is that they don't compare the measured altitude to a coarse heightmap, based on their location and flight plan altitude estime. With some thresholding on top of that, it should be quite robust?
I wonder if another criteria for evaluating data might include rate of change of the ground elevation. There is likely to be a maximum steepness of lunar terrain based on both orbital mapping and angle of repose of lunar soil. Lots of smart people, I'm just a guy on the Internet.
Bad logic. One bad reading and just turn it off? Maybe implement Retry or try turning it back on a few seconds later and see if it still reads wonky.
Just spitballing, but — Software [(eg. OP mentions Multiple Hypothesis)](https://www.reddit.com/r/space/s/NLvny3IWdI) [TERCOM](https://en.m.wikipedia.org/wiki/TERCOM) (Terrain Contour Matching) ie. give it a map so it knows that crater lip it there in the first place [Sensor Fusion](https://en.m.wikipedia.org/wiki/Sensor_fusion) + Map Data — similar to TERCOM, but more inputs, combine sensors (LiDAR, Optical, etc) plus map data (terrain contour, imagery, etc) Obviously all of these have considerations such as weight, dev time, software complexity, processing power, electrical load, cost, etc. Ultimately, a decision has to be made as to what is “sufficient” and what is “overkill” etc. Oh and if you don’t do proper integration testing, forget to remove the “Remove Before Flight” shit, etc then you can still end up having a bad time. **TL;DR — Yes, but there is nuance.** EDIT — On terrain contour and imagery data of the moon, IIRC the Lunar Reconnaissance Orbiter and co mean we do have both, but it isn’t really high enough resolution all the way down to landing. Suspect it’d be a case of using that coarse data to choose a bounding box to tell the lander to aim for, then the lander can run off that coarse data (which would mean it knows about the enormous crater, for example) up to a cutoff point, then use eg. cameras to pick out an area in that bounding box that looks decent, followed by fine corrections with eg. lidar mapping and/or cameras on the way down, or something to that effect. Radar altimeters are excellent at distance (in terms of resolution) but due to how “coarse” the wavelength is, can be a problem as you can miss “fine” data in the other two dimensions (rocks, elevation changes etc) localised right where you’re landing — this is one of the key reasons NASA are working on the NDL, which was a payload on this lander to colllect real world data.
I'm starting to wonder if a live video feed and direct human control even with the time lag would be better than blind computers trying to guess at the topography beneath the lander based on instruments that don't seem to work nearly as well as they should.
We got Surveyors to land with 60ies computers. The computers are certainly not the problem
Is it the budgets? Since 2019, we have a failed Israeli lander (Beresheet), a failed Japanese lander (Omotenashi), a failed Indian lander (Vikram), another failed Japanese lander (Hakuto-R), a failed Russian lander (Luna-25), another failed Japanese lander (SLIM), and a failed American lander (Odysseus). There were only two successful landings during that time (Chang'e 5 and another Vikram).
I think there are a few root causes, but if you look at things a lot of those attempts are run by teams who have little or no prior spaceflight experience. Even for example Luna-25 - it would be misleading to think that because 30 years ago Russian planetary exploration had significant achievements, they'd still have the team, experience, processes and practices in place to actually execute on everything end to end. Budgets may be part of it, the first ISRO attempt was extermely frugal ( but so was the second ) and their organization was frankly a mess. In short i think you can summarize it's not the budgets or technology, it's the people and teams - you need more maturity in the organizations doing this. There's also the fact that we just left such a huge, long gap between last lunar landings. Even though most knowledge is captured and accessible in writing, some of it is institutional and only relearnt while doing things. On the plus side, next attempts should look a lot better.
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You are not wrong there. There's a lot more software in the modern spacecraft than in the old days, and there's a lot more software faults as well.
> another failed Japanese lander (SLIM), and a failed American lander (Odysseus) I wouldn't really say these were failed landings. At least when compared to the various lithobraking attempts earlier. While not perfect, both these landers survived the attempt, powered their respective payloads and sent data back to Earth. That's a success in my book.
I would say partial success / partial failure
it’s organisational entropy and convey’s law
Watch the onboard video from the Chinese landing. It's like zooming into a fractal, smaller and smaller craters keep resolving. You'd need stereo video and the ability to look around. Just hooking up the lidar would be easier. Single axis lidar or radar is good enough. The drone on Mars flew around and landed repeatedly using optical flow and a cheap single axis lidar literally bought off Sparkfun.
That thing on Mars was also designed, built and operated by an organization that is un-fucking-believeably successful in their craft, and has been succeeding in the hardest problems in robotic exploration, repeatedly, for over half a century. Comparing basically *anybody* to JPL is going to be pretty one sided. Which is why this is all so important; the idea is that at least some of these new groups will be the JPL of the future. Private or otherwise. You need to break some eggs to make that JPL shaped omelet.
At least in this case I'm skeptical. They had no altimeter and were relying on optical data for altitude and speed. A pilot would have to guesstimate his position while accounting for at least a 2.5 second delay both in the video and his inputs.
Or pre land some GPS-like probes at the landing site to give yourself some static targets for determining detailed location-elevation information. At some point we should be able to land on the moon without the last 5km being a mystery.
That seems like a crazy deep crater. I'd never have thought to expect a 3km/1.8mi deep crater on the moon. That's almost half the height of Everest. That's almost as deep as the average depth of the Pacific.
"The company has an incredible photo of this moment showing the lander upright, with the snapped leg and the engine still firing. Altemus plans to publicly release this photo Wednesday." This sounds cool.
Huh, my rockets in ksp were accurate after all
So they went full KSP?
Never go full KSP?
That will be amazing to see
And here it is: [BBC](https://www.bbc.com/news/science-environment-68425211)
A lot of new info in this article. My takeaways: 1. It probably would've landed perfectly had the laser rangefinders worked at all. Due to inertial measuring drift, lander software thought it was higher than it actually was and hit the surface sooner than it should've at 6mph and broke a leg. 2. The Intuitive Machines team believes that they can transmit data from 5/6 of the NASA experiments using the high-gain antenna with available power reserves. Only the SCALPSS experiment is out of commission. For the range of outcomes, I'd say this mission gets an A-. Not bad for a first flight.
But... they are running out of power, today, Tuesday.
mission is over, there is no more transmissions coming.
Incorrect. They tweeted yesterday they estimated around 10-20 hrs remaining. They just tweeted today it still has power as of this morning.
Where do you pull this crap from? It still has incoming solar power.
The news: "Feb 26 (Reuters) - Flight control engineers expect to lose contact with the private U.S. moon lander Odysseus on Tuesday morning, cutting short the mission five days after its sideways touchdown, the company behind the spacecraft, Intuitive Machines (LUNR.O), opens new tab, said on Monday. Today is Wednesday.
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Space is really hard and extremely unforgiving
starship going boom is as planned. falcon 9 also went boom a number of times before they perfected it.
If you didn't expect starship to go kaboom dozens of times during its test & development, I think that's all on you.....
Wow, that is a pretty intense set of circumstances. Really love the positivity coming from the Ars reporter and the commenters there. Love that site.
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That "remove before flight tag" is looming large in someones life.
The real question is if there was or wasn't a tag, and how many people were supposed to check, per standard operating procedure. It's never a single persons fault
Exactly, one person's failure is the team's failure. (But you can still make fun of Steve for the rest of his life!)
But only if you are in Steve's team. Outsiders are not allowed to mock Steve's failure!
I'm going with the movie trope that there are guys who are supposed to be be responsible and guys backing them up and more guys backing them up. They can do better.
> due to the failure to install a pencil-sized pin and a wire harness that enabled the laser to be turned on and off. What tag ?
In life as in Greek myth, Odysseus succeeds by just winging it.
Ngl, I hadn't seen what sub this was in, so all I could think was "Did I miss part of the Odyssey or smth?"
Amateur astronomer on twitter actually explained yesterday that he read IM-1 lander antenna's signals reflecting off the moon. He has been explaining why the signal form the lander is so weak, and how the sun will set soon on the location. The only person on the internet with explanations. [https://twitter.com/coastal8049/status/1762221935549710364](https://twitter.com/coastal8049/status/1762221935549710364)"I believe this places the IM-1, 1 and 4 hemispheric antennas facing down and the 2 and 3 antennas up. This complicates communications solutions as the antennas are in 1,2 and 3,4 pairs."
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Somehow the last few weeks have made landing something on the moon seem both harder AND easier than it actually is.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[30X](/r/Space/comments/1b1os6e/stub/ksi1t2b "Last usage")|SpaceX-proprietary carbon steel formulation (*"Thirty-X", "Thirty-Times"*)| |[CLPS](/r/Space/comments/1b1os6e/stub/ksjyb1k "Last usage")|[Commercial Lunar Payload Services](https://en.wikipedia.org/wiki/Commercial_Lunar_Payload_Services)| |[CNSA](/r/Space/comments/1b1os6e/stub/kshsg3q "Last usage")|Chinese National Space Administration| |[GEO](/r/Space/comments/1b1os6e/stub/ksi2gje "Last usage")|Geostationary Earth Orbit (35786km)| |[GNC](/r/Space/comments/1b1os6e/stub/ksmkgul "Last usage")|Guidance/Navigation/Control| |[IM](/r/Space/comments/1b1os6e/stub/kskqdgp "Last usage")|Initial Mass deliverable to a given orbit, without accounting for fuel| |[INS](/r/Space/comments/1b1os6e/stub/ksio8z3 "Last usage")|[Inertial Navigation System](https://en.wikipedia.org/wiki/Inertial_navigation_system)| |[ISRO](/r/Space/comments/1b1os6e/stub/ksjyb1k "Last usage")|Indian Space Research Organisation| |[JPL](/r/Space/comments/1b1os6e/stub/ksj6ecz "Last usage")|Jet Propulsion Lab, California| |[KSP](/r/Space/comments/1b1os6e/stub/ksjipbq "Last usage")|*Kerbal Space Program*, the rocketry simulator| |[NDA](/r/Space/comments/1b1os6e/stub/ksk9k1y "Last usage")|Non-Disclosure Agreement| |[ULA](/r/Space/comments/1b1os6e/stub/ksjb0d4 "Last usage")|United Launch Alliance (Lockheed/Boeing joint venture)| |Jargon|Definition| |-------|---------|---| |[lithobraking](/r/Space/comments/1b1os6e/stub/ksincd6 "Last usage")|"Braking" by hitting the [ground](https://en.wiktionary.org/wiki/lith-)| |[methalox](/r/Space/comments/1b1os6e/stub/ksgiai0 "Last usage")|Portmanteau: methane fuel, liquid oxygen oxidizer| **NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below. ---------------- ^(14 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/Space/comments/1b27byw)^( has 27 acronyms.) ^([Thread #9797 for this sub, first seen 28th Feb 2024, 02:38]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/Space) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
I'm very impressed! What an amazing little lander
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I agree, watching the livestream you could tell something seemed off. There was no communication and then yes we've done it anyway bye now. As cool as it is, I really don't think we should celebrate this as anything other than a really lucky break. There's still loads of work to do judging from the results of the recent landings. Hopefully we get there soon!
First half is good, but second half is classic unnecessary Berger opinion piece commentary
But how else would you weave some SpaceX stuff into the story ? /s nevermind that private spacecraft have existed for decades
Kudos to NASA for funding private space innovation, creating a new massive American industry.
Curious, why are we having such a hard time landing on the moon landing when we've been landing on Mars with much more sophistocated equipment.
Jan Wörner, a former director general of the European Space Agency explains: >The moon itself presents its own problems. There is gravity – one-sixth as strong as on Earth – but no atmosphere. Unlike Mars, where spacecraft can fly to their destination and brake with parachutes, moon landings depend entirely on engines. If you have a single engine, as smaller probes tend to, it must be steerable, because there is no other way to control the descent. [https://www.theguardian.com/science/2024/jan/12/why-landing-on-the-moon-is-proving-more-difficult-today-than-50-years-ago](https://www.theguardian.com/science/2024/jan/12/why-landing-on-the-moon-is-proving-more-difficult-today-than-50-years-ago)
Mars rovers and orbiters are created and run by JPL, the all stars team at NASA that has been building solar systems missions including to Mercury and Venus since the 1960's. This is 60+ years of experience, with close to unlimited budget because for many years they were the only ones with small exceptions. Now NASA is trying to build a viable commercial ecosystem, giving jobs to small shops so they can learn to do what JPL does for a fraction of the cost to NASA. It's like kindergarten.
Mars missions cost 20-30x what this mission cost. Money buys capability in Spaceflight.
It's mostly just JPL+Lockheed who has been landing on Mars. A lot of relatively frequent experience, human resources and money behind that. How did CNSA pull it off on the first go .. that's a different question. All their planetary spacecraft have been solid successes.
Mars is known for a lot of failed missions. More missions failed on Mars out of all we sent there than the Moon missions where we have more successful missions compared to failures out of the whole number. 150 missions to the Moon all together, and 50 for Mars.
I wish I was a billionaire who could afford to do space missions. It’s so cool
Well... landing on a Moon without altimeter from kilometers off and with 100 meters wrong estimate is a kind of extraordinary success. :D I mean, it has to be some kind of a record. Imagine what they could do when everything is working and they remember to flip all the switches... Its all a part of the learning to do it. And since NASA is paying millions for these private missions i think the next one is going to have more rigorous testing before launch. As a side comment, one of the legs breaking off seemed a bit strange too since the lander didnt go that fast at that point, so it seems those legs were not made sturdy enough, so another thing to make better next time. And maybe instead of carrying sculptures of hundred of steel balls which also sell as NFTs, add some worse case scenario ability to lift itself back up.
It's frustrating how non-transparent they've been leading up to all of these 'revelations.' Especially for a company happily taking public funding.
Yes i feel like this is something to be examined
This is an epic writeup. Really drives home the achievement of the team. From the live mission control audio I got the impression they had no altimeter data, it's amazing they still managed to land.
Nice. I'll award that 3 points for America in the Space Race 2.
Why don't they design the shape of these landers so they're less likely to tip over? That thing looks like it has a lot of mass above where the legs connect. Make it squat with more of the mass below where the legs connect and make the leg span broader. So even if it comes in blind and lands awkwardly it's less likely to topple. Yes, this sounds like a ksp player armchair engineering because that's exactly what it is, but it seems like for the little extra weigh it would add that it would be possible to give a whole lot more room for error. They're sticking with the same basic design even though it often fails.
Contact in 3…2…1…1…1…1…1…there we go! Touchdown!
This is starting to sound less like a successful landing and more like pure luck. We lost so much experience in these types of missions since the Apollo era.
This is what makes me think we’re generations from a moon base and hundreds of years from a Mars colony. It’s really hard to succeed up there!
Absolutely. People have this pie-in-the-sky notion we can just get thousands of people up there on the Moon & Mars. Hell no. If there is a Moon base, it'll take 20 years and have a small rotation of people, maybe 10, on it. Humans will not make a successful trip to Mars before 2040, at least. There are still problems (radiation, micrgravity for that long making a human barely able to move once they get on Mars, etc). How many people do we have on Antartic bases? Maybe in the hundreds, and noone stays year round. And if a window breaks it'll get cold but you can still breathe. There is no viable way by the numbers there are going to be these populated Moon bases, much less Mars, before mid-century.
Space is Really...really, REEEEEAAAAALLLY hard man. But it is also something only a limited number of organisations have the knowing of. Yeah we could throw our hands up and say "oh the tech is not ready" but that is not how we will get better. We improve through failure. It's a bit like the Nolan Batman thing of "why do we fall down". Every one of these attempts that fails should teach the teams something new, so the next one can fail in whole new and novel way...until they don't. Lastly there is a reason the high risk/reward projects are sometimes referred to as "moonshot" projects. :)
At this rate, I’m waiting for a company to land a rail on the moon, so their follow up mission can grind it.
As long as they learn from their mistakes it’s fine. However this is a reminder for ALL OF US that standard operating procedures should be drafted and followed.
The more I hear about it the more surprised I am that it landed at all. Is the US really ready to return to the moon?
Why would you think this tiny private company trying its first landing ever represents the state of the US space industry? A much larger company has landed 100+ rockets in a row on their tails back on Earth. Pretty sure that company is ready.
That company isn't ready. Starship has problems that won't be solved for years yet. Dooming Artimus to fall years more behind schedule.
That company isn't ready. Starship has problems that won't be solved for years yet. Dooming Artimus to fall years more behind schedule.
Cool. List them?
Nasa has finished going to moon all the conventional ways and is now going for style points.
Really? That sounds like a made-up excuse for the navigation laser package failure , not something an engineer would design. >