ISpace discloses why its lunar lander crashed

Jan

Jan

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Why the ISpace moon lander crashed

The crash of the ISpace moon lander in April 2023 was reportedly due to a software issue that falsely reported altitude readings and resulted in the spacecraft running out of fuel before touching down, the company said in a statement.

The moon lander was supposed to land in an open, flat plain. However, the target landing area changed to the rim of a crater several months before the vehicle's launch, confusing its onboard software.
 
“Based on the review of the flight data, it was observed that, as the lander was navigating to the planned landing site, the altitude measured by the onboard sensors rose sharply when it passed over a large cliff approximately 3km in elevation on the lunar surface, which was determined to be the rim of a crater,” ISpace said.

“According to the analysis of the flight data, a larger-than-expected discrepancy occurred between the measured altitude value and the estimated altitude value set in advance.”

It notes that a major contributing factor to the crash was a decision to change the landing site after a critical design review in February 2021.

“This modification influenced the verification and validation plan despite numerous landing simulations carried out before the landing,” ISpace said.
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In other words, they didn't re-simulate the system to check whether it could land at the designated landing site.

Good video on it here:


Summary:
When the lander flew over the cliff, its ground radar measured a very large change in altitude, which caused their control systems to start ignoring that radar because it had an "abnormal reading", so it had to start relying on other sensors and measurements to estimate the altitude. This causes drift in the altitude reported to the landing control system, which meant it started the landing sequence 5km off the ground. It then ran out of fuel.
 
konfab said:
In other words, they didn't re-simulate the system to check whether it could land at the designated landing site.

Good video on it here:


Summary:
When the lander flew over the cliff, its ground radar measured a very large change in altitude, which caused their control systems to start ignoring that radar because it had an "abnormal reading", so it had to start relying on other sensors and measurements to estimate the altitude. This causes drift in the altitude reported to the landing control system, which meant it started the landing sequence 5km off the ground. It then ran out of fuel.
Click to expand...

I posted that link in a parallel thread on Friday:

Japan's Ispace moon lander assumed lost after attempted landing

Ispace moon lander may have crashed Tokyo-based Ispace Inc. said it could not confirm if its spacecraft successfully landed on the moon. The company’s chief executive said it assumed the landing failed. It was poised to become the first commercial space company to place a lander on the moon...
mybroadband.co.za mybroadband.co.za
 
For some reason it reminded me of Astro Chicken.

Old farts who've played Space Quest 3 should recognize the name.

Here it is, in its full glory : (spoiler - you need to eat something from the burp-o-bar to get an item which will help you decode a cryptic message)

 
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Reactions: Jan
Seems a lot harder these days to land unmanned spacecraft on the moon than it was to land people there in the 1970s.
 
LCBXX said:
Seems a lot harder these days to land unmanned spacecraft on the moon than it was to land people there in the 1970s.
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Only seems, if you don't bother to think about it.

Those who landed people back then basically had unlimited money and hundred of thousands of people to get the job done. Recent lander missions such as Hakuto-R and others mentioned by Scott Manley are designed, developed and run by tiny teams on miniscule budgets and very limited resources.
 
Arthur said:
Those who landed people back then basically had unlimited money and hundred of thousands of people to get the job done. Recent lander missions such as Hakuto-R and others mentioned by Scott Manley are designed, developed and run by tiny teams on miniscule budgets and very limited resources.
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Also let's not undervalue having a decorated human combat fighter pilot in the lander with a Sc.D. from MIT in astronautics whose thesis was "Line-of-Sight Guidance Techniques for Manned Orbital Rendezvous".

In general, automating something is much harder than having a human around to compensate for unforeseen circumstances.

Anyone who played the Dr. Brain games knows this.
 
LCBXX said:
Seems a lot harder these days to land unmanned spacecraft on the moon than it was to land people there in the 1970s.
Click to expand...
Humans are adaptable. If the radar gave a funky reading, they would have simply looked out the window to verify, and then reset the system.
 
LCBXX said:
Seems a lot harder these days to land unmanned spacecraft on the moon than it was to land people there in the 1970s.
Click to expand...
Humans are adaptable. If the radar gave a funky reading, they would have simply looked out the window to verify, and then reset the system.
 
konfab said:
Humans are adaptable. If the radar gave a funky reading, they would have simply looked out the window to verify, and then reset the system.
Click to expand...
This is what happened to Apollo 11. They ran into a similar problem to the Japanese lander (a deep crater before the landing site). They saw that this was giving funky readings and compensated. It also means that this has been a known issue for over 50 years so maybe it should have been better accommodated in the software testing.
 
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