Posts: 1296 From: Vancouver, WA, USA Registered: Feb 2012
posted 02-26-2024 11:18 AM
Did NASA or IM provide the coordinates of the target landing site before the mission launched?
The 85 degree South to which I referred in a previous message was determined from a medium resolution map on another website. A nearly 5 degree difference, if true, would not be considered a success in the accuracy department.
Also, do we know the approximate length, width, and height of Odie, with and without landing gear?
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-26-2024 11:40 AM
Length 3m (length and height being the same) Diameter 2m (which equates to width and depth).
It landed at Malapert A, its intended destination (which quite frankly IS a success in the destination department).
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-26-2024 12:39 PM
As the moon's gravity is approximately 1/6 that of Earth, wouldn't a lateral motion of x mph impart six times the rotational energy to the top of the lander if a foot impacted a rock than would be the case on Earth? In other words, despite having a low centre of gravity, doesn't a lunar lander need to be shorter (less tall) than an equivalent Earth lander?
A shorter, squatter lander may well have overcome the unplanned lateral motion at landing and survived upright. And if so, isn't it obvious that Odysseus was too tall given that the lander did have lateral motion where none was planned?
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-26-2024 01:00 PM
Scott Manley addressed the lander's height in a thread on X:
There are lots of comments about the Nova-C lander being too tall, contributing to the tip over on landing.
Let's consider why it's this shape:
Firstly the landing legs are as wide as they can get for the Falcon 9 fairing without requiring a deployment mechanism.
Secondly, the core of the vehicle is the propulsion, and two propellant tanks. These are mounted inline because it makes for the lightest design, the propellant tanks are different sizes and masses so putting them side by side makes balancing more complex.
A common way to avoid the asymmetric mass problems is to use pairs of tanks, here's the Morpheus lander as an example. But, this in turn means adds a lot of mass between more material needed for the tanks, extra plumbing, valves and structure.
Inline tanks save mass.
Furthermore this was a spacecraft designed for the poles so the tall sides provide a good place to put solar panels, and antenna. Both benefit from being higher up above local terrain compared to more squat lander designs.
The actual tank sizes would be constrained by the vehicle performance requirements, so that sets the overall height of the vehicle.
NukeGuy Member
Posts: 116 From: Irvine, CA USA Registered: May 2014
posted 02-26-2024 02:24 PM
An object’s moment of inertia depends on its mass not weight.
Jim Behling Member
Posts: 1895 From: Cape Canaveral, FL Registered: Mar 2010
posted 02-26-2024 03:12 PM
quote:Originally posted by Axman: ...doesn't a lunar lander need to be shorter (less tall) than an equivalent Earth lander?
Wider legs and it had them.
Part of the issue with lateral motion and faster descent velocity was due to using the NASA experimental LIDAR, which was used instead the non-operating LIDAR which was part of the lander's avionics.
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-28-2024 10:22 AM
As it turns out, Odysseus landed without any way of knowing its exact altitude. From Ars Technica:
...the flight computer onboard Odysseus was unable to process data from the NASA payload in real time. Therefore, the last accurate altitude reading the lander received came when it was 15 kilometers above the lunar surface — and still more than 12 minutes from touchdown.
That left the spacecraft, which was flying autonomously, to rely on its optical navigation cameras. By comparing imagery data frame by frame, the flight computer could determine how fast it was moving relative to the lunar surface. Knowing its initial velocity and altitude prior to initiating powered descent and using data from the inertial measurement unit (IMU) on board Odysseus, it could get a rough idea of altitude. But that only went so far.
"So we're coming down to our landing site with no altimeter," Altemus said.
Unfortunately, as it neared the lunar surface, the lander believed it was about 100 meters higher relative to the Moon than it actually was. So instead of touching down with a vertical velocity of just 1 meter per second and no lateral movement, Odysseus was coming down three times faster and with a lateral speed of 2 meters per second.
"That little geometry made us hit a little harder than we wanted to," he said.
But all was not lost. Based upon data downloaded from the spacecraft and imagery from NASA's Lunar Reconnaissance Orbiter, which flew over the landing site, Intuitive Machines has determined that the lander came down to the surface and likely skidded. This force caused one of its six landing legs to snap. Then, for a couple of seconds, the lander stood upright before toppling over due to the failed leg.
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.
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-28-2024 12:54 PM
NASA live video
NASA and Intuitive Machines give an update from Johnson Space Center in Houston to highlight the company's first mission, known as IM-1.
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-28-2024 02:28 PM
Embry-Riddle's EagleCam was ejected from Odysseus earlier today but something occurred with its camera or onboard data system such that no images have been received. The Intuitive Machines team is working as best they can to see if they can retrieve an image.
Odysseus has about five hours of battery life remaining before it will no longer operate, but Intuitive Machines will try to wake the lander after the lunar night with hopes it may survive the deep cold.
spaced out Member
Posts: 3209 From: Paris, France Registered: Aug 2003
posted 02-28-2024 02:37 PM
Glad you got a question in there Robert — and kudos for asking one that surprised the panel and prompted them to think about something that obviously hadn't occurred to them.
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-28-2024 02:51 PM
Thanks!
Now I just hope since I gave them the idea, they will give me the scoop when they are ready to announce their choice.
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-28-2024 03:03 PM
I'm incredulous. The lander came in faster than expected and with unplanned lateral motion and "skidded" to a stop and broke one of its six legs, but was upright. And then toppled over! What?
How can an object with six legs topple over because one is broken? Absolute nonsense.
It would appear that somebody needs to sit down with the top bods at Intuitive Machines and explain to them in plain English what "moment of inertia" means...
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-28-2024 03:26 PM
You omitted a key point and mixed up some of the order of events.
According to Intuitive Machines, the lander came in faster than expected and with an unplanned lateral motion, hit the surface hard, which resulted in breaking off one of the legs. It then proceeded to skid across the surface. Once it came to a halt, it sat upright as its engine continued to fire. It was only after engine cut off did the lander slowly tip over due to being on uneven ground (about a 12 degree slope).
(Also, while they know for certain they broke off one of the landing gear, they said today that a second leg may been lost, too.)
Blackarrow Member
Posts: 3700 From: Belfast, United Kingdom Registered: Feb 2002
posted 02-28-2024 08:25 PM
quote:Originally posted by spaced out: Glad you got a question in there Robert
What was the question? And the answer? (I missed the press conference.)
Headshot Member
Posts: 1296 From: Vancouver, WA, USA Registered: Feb 2012
posted 02-28-2024 08:34 PM
Ditto Geoffrey's post.
I missed Robert's question too.
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-28-2024 09:42 PM
See the last couple of paragraphs of this article.
(Or if you're in a rush, I asked about naming Odysseus' landing site.)
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-29-2024 06:59 AM
quote:Originally posted by Robert Pearlman: You omitted a key point and mixed up some of the order of events.
My order of events followed those outlined in the previous Ars Technica report, and I'm not sure which key point I omitted.
Basically, to rephrase everything, what I am saying is this: the lander didn't topple over due to breaking a leg. Whether all or none of the legs survived the landing was irrelevant to the toppling.
The probe toppled because it came in with lateral motion. On first grounding with the lunar surface that lateral motion was converted to rotational energy because the top continued to move when the bottom didn't (or at the very least, if a 'skid' took place, then the top continued to move much faster than the bottom).
This is Moment of inertia [i.e., the opposition that a body exhibits to having its speed of rotation about an axis altered by the application of a torque (turning force)]. Moment of inertia is not just dependent upon mass and centre of gravity; the shape of an object also factors into Moment of inertia...
So, to summarise: The landing probe toppled not because it had a broken leg, but because it had unplanned lateral motion and it was too tall.
Jim Behling Member
Posts: 1895 From: Cape Canaveral, FL Registered: Mar 2010
posted 02-29-2024 08:01 AM
That is wrong. It was upright not moving when the engine cut off.
quote:Originally posted by Axman: A shorter, squatter lander may well have overcome the unplanned lateral motion at landing and survived upright. And if so, isn't it obvious that Odysseus was too tall given that the lander did have lateral motion where none was planned?
Unknown from the data available to us. Also, it is known a squatter lander would be more expensive and not accommodate the experiments and mission as designed.
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-29-2024 09:17 AM
Well I beg to disagree. It landed with lateral motion. On the moon. Where gravity is 1/6 that on Earth. The energy is there, the moment of inertia is there. A pause of a second or two in an upright position is when the torque force overcomes the centre of gravity (especially remembering that everything takes longer in the moon's reduced gravitational field).
And if you still disagree, I don't understand what mechanism you are ascribing to its toppling?
It did topple... it fell over.
If it fell over because it was upright and stationary on a 12° slope - it Was too tall.
If it fell over because it merely broke a leg (or even two), given it had six legs - then, it was too tall.
I don't understand what your objection is to my statement that it was "too tall." Nor do I understand what it is that you think made it topple over!
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-29-2024 10:43 AM
The engine continued firing long past Odysseus landed on the moon (because without altitude data, the on board computer thought the lander was still 100 meters or more off the surface).
According to Intuitive Machines, after the skid ended, the engine nulled the lateral motion and the lander was standing upright (according to inertial sensors) when the thrust finally cut off. Unfortunately, the land below Odysseus was not level and missing one or two of its legs, the lander slowly fell over.
So yes, the lander was too tall to land on an incline if it only had four unevenly-distributed legs, but it was never designed to do that (nor should we expect Intuitive Machines or any company to design for such a scenario).
As they said yesterday, they are not planning any major redesigns of the vehicle* before flying again later this year. They are confident if the laser altimeters were powered on (a mistake they will never make again), they would have stuck the landing.
* They do plan to add more cameras and antennae.
Headshot Member
Posts: 1296 From: Vancouver, WA, USA Registered: Feb 2012
posted 02-29-2024 12:29 PM
That is good news about adding more cameras.
I am a firm believer of the dictum: The general public's perception of of a successful space mission is directly proportional to the number of images received.
On another note: the UnmannedSpaceflight.com has a nice thread about Odie. Some members have been REALLY playing around with the images received thus far and have even spotted the broken-off foot pad lying on the lunar surface.
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-29-2024 01:08 PM
quote:Originally posted by Robert Pearlman: The engine continued firing long past Odysseus landed on the moon (because without altitude data, the on board computer thought the lander was still 100 meters or more off the surface
Sorry to be a pain, but this just doesn't make sense.
Firstly, if the engine continued firing once the probe had touched down, it would have taken off again! Secondly, if it continued firing long past touchdown, it would not only have taken off again, but would have subsequently crash landed in an uncontrolled descent. Thirdly, a vertical engine firing downwards cannot annul a lateral motion.
Those three points are facts grounded in physics and not just 'opinions' I hold.
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-29-2024 01:21 PM
The engine can both throttle and gimbal.
I don't have access to the telemetry data that Intuitive Machines has, but even under a nominal landing, the engine was expected to continue firing all the way down to the surface.
As an aside, Apollo 11 did the same. Had Neil Armstrong not taken over manual control, the computer would have cut off the engine at the point the landing probe touched the surface, letting the lunar module then drop to the ground. But with Armstrong flying, the engine continued firing all the way down, through touchdown. The first words spoken on the moon were by Aldrin, "Okay. Engine Stop."
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-29-2024 01:32 PM
Sorry Robert, again it doesn't make sense to me.
Whether the engine could gimbal and throttle or not, if the probe didn't know its altitude how could it adjust for lateral motion?
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-29-2024 01:43 PM
The lander had an inertial measurement unit that sensed "acceleration like a human's inner ears, which feel rotation and acceleration" (quoting the IM-1 press kit).
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-29-2024 01:51 PM
Here is where I'm "failing to compute."
If it had an inertial guidance system that told it that it had lateral motion that was outside its parameters, why did it not adjust for that? And if the answer to that is because it had no idea how high it was, then in what possible way are you arguing with my assessment of why it toppled over?
Because really, it is quite silly to say it merely fell over after it was upright and stationary and everything was good, engines cut off, lateral motion annulled, everything hunky dory. Just a tiny matter of having lost one leg out of six and standing on a 12° slope. Uh-oh I feel myself toppling over...
Jim Behling Member
Posts: 1895 From: Cape Canaveral, FL Registered: Mar 2010
posted 02-29-2024 02:48 PM
quote:Originally posted by Axman: ...if the engine continued firing once the probe had touched down, it would have taken off again!
No, not if the thrust versus weight was less than one.
quote:...a vertical engine firing downwards cannot annul a lateral motion.
The engine can gimbal and there still attitude and translation thrusters.
quote:If it had an inertial guidance system that told it that it had lateral motion that was outside its parameters, why did it not adjust for that?
Inertial guidance system is inadequate for height knowledge. The vehicle thought it was much higher when it first hit. After it hit, it had zero vertical velocity, so it tried to null the horizontal component, while missing one leg and dragging another damaged one.
Headshot Member
Posts: 1296 From: Vancouver, WA, USA Registered: Feb 2012
posted 02-29-2024 03:31 PM
quote:Originally posted by Axman: ...if the engine continued firing once the probe had touched down, it would have taken off again!
Not true. You cannot make a blanket statement like that without considering the fact that Odie's engine is throttle-able. Whether or not Odie would have taken off again would have been strictly determined by the engine's throttle setting. At a slightly higher setting, Odie would not have even contacted the lunar surface.
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-29-2024 04:20 PM
So who precisely was controlling this "throttle ability"? I mean, really? Get a grip!
The probe fell over. It came in too hard, too slanted. It had too much lateral motion. It had no idea how high it was. It was too tall. It fell over.
Those are facts. Stop trying to paint a pig as a cow.
(As a private message reminds me, Surveyor 3 underwent a similar process. It ended upright despite bouncing three times because the thrust wasn't turned off. But then again it wasn't a ridiculously tall cylinder on spindly legs.)
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-29-2024 04:30 PM
Physics. Physics that even a fourteen year old should know. I really think before anybody posts another rebuttal, please consider this:
As a fact, the probe fell over. Fact.
Nobody has a convincing argument as to why that happened without involving how tall the probe is. Fact.
So. Instead of countering my argument with blithe statements, tell me why it 'toppled.'
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-29-2024 04:34 PM
Why do you feel you know better than the team of engineers at Intuitive Machines who have access to data, visuals and information about their lander that you (and I and everyone else) do not?
Do you really think a company capable of building a NASA-approved lander does not understand the physics and engineering behind their own vehicle?
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 02-29-2024 04:38 PM
Well you said it...
Sometimes it's best not to trust what the top dogs say. And sometimes the engineers get bullied into things the top dogs want. O rings and freezing temperatures spring to mind.
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-29-2024 05:13 PM
Okay, this is not that.
I don't know how much you know about the leadership of Intuitive Machines, but they aren't only businessmen. They are engineers. CEO Steve Altemus was previously the director of engineering for Johnson Space Center. Tim Crain, the chief technology officer, helped developed the navigation system for the Mars Science Laboratory (MSL, also known the Curiousity rover) and then was the Guidance, Navigation and Control lead for the Morpheus propulsion test vehicle developed at Johnson Space Center.
Jack Fischer, who headed the production of Odysseus and leads operations, is a former NASA astronaut and U.S. Air Force test pilot with a Master's degree in astronautics from MIT.
These aren't suits who don't understand what they are describing, nor do they have any reason to cover up anything.
Blackarrow Member
Posts: 3700 From: Belfast, United Kingdom Registered: Feb 2002
posted 02-29-2024 05:52 PM
How exactly do we define "success" in the context of a lunar landing?
I see that Intuitive Machines claims that Odysseus "soft-landed" on the Moon. This reminds me of the old aviation dictum that "any landing you can walk away from is a good landing" (by which yardstick I have 296 out of 297 good glider landings). Odysseus didn't make what I would define as a "soft" landing, but on the other hand it was robust enough to survive toppling over and to transmit images and data from the surface (like Galileo, via a low-gain antenna rather than the desired high-gain).
If the vehicle had had a crew on board, this would almost certainly have been remembered as the greatest failure and tragedy of lunar exploration to date. But of course there was no crew, so I suggest we treat the mission as a qualified success, with many achievements to carry forward to the next mission. But to refer to a "soft" landing is a bit of a stretch.
Robert Pearlman Editor
Posts: 52131 From: Houston, TX Registered: Nov 1999
posted 02-29-2024 06:21 PM
If the vehicle had a crew aboard, it would have been designed differently. Nova-C was specifically created to accomplish what the "C" in its name stands for: deliver 100 kilograms of payload to the lunar surface.
Odysseus did that and in a manner that all of its commercial and NASA-provided instruments were able to function and/or send back data.
History (and Wikipedia) records that the first spacecraft to make a soft landing on Mars was the Soviet Union's Mars 3. The mission is considered a partial success because all contact was lost with the probe 110 seconds after it landed.
With that in mind, Odysseus' seven days operating on the moon (and with a good deal of luck, maybe more) has to be a success.
GACspaceguy Member
Posts: 3042 From: Guyton, GA Registered: Jan 2006
posted 02-29-2024 06:38 PM
quote:Originally posted by Blackarrow: If the vehicle had had a crew on board...
I suggest that if it were crewed it would never been given a "go" for landing. Without the full navigation package, I would assume mission rules would require an alternate mission. With a nonhuman vehicle the only thing at risk is the vehicle.
But conjecture is just that a guess.
Jim Behling Member
Posts: 1895 From: Cape Canaveral, FL Registered: Mar 2010
posted 02-29-2024 07:19 PM
quote:Originally posted by Axman: Instead of countering my argument with blithe statements, tell me why it 'toppled.'
Because three of the six legs were missing or damaged.
quote:So who precisely was controlling this "throttle ability"?
The guidance system was. I don't know why you can't understand this.
Axman Member
Posts: 423 From: Derbyshire UK Registered: Mar 2023
posted 03-01-2024 08:34 AM
I quite understand it Mr Behling. But a guidance system that doesn't know how high the craft it is guiding in is, isn't an optimal system.
And, your post above is the very first time I'd heard that three legs are now missing...
Blackarrow Member
Posts: 3700 From: Belfast, United Kingdom Registered: Feb 2002
posted 03-01-2024 12:14 PM
quote:Originally posted by Robert Pearlman: If the vehicle had a crew aboard, it would have been designed differently.
Of course. But that's not the point. If a crewed vehicle (let's say an Apollo LM) had made a landing like that, it would have been a tragedy, not a success. Obviously Odysseus had no crew, but I maintain that it is a bit of a stretch to say that a vehicle which hit the surface too fast, skidded, lost a couple of landing-legs and toppled over (putting the main communications antenna effectively out of use) was an unqualified success.
Odysseus did not land the way it was supposed to. Its contact with the surface was anything but "soft" so if the mission objective was a "soft landing" then it fell short and I again say its success was partial or qualified.
posted 02-26-2024 11:18 AM
advertisement