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#320 by Blackstar on 31 Dec, 2022 23:54
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Sorry to flog the dead horse
Flog away.
Don't assume that this question was not asked 20+ years ago. -
#321 by ccdengr on 01 Jan, 2023 00:04
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InSight lasted significantly beyond its design life.
This. No spacecraft is designed to last indefinitely. They are designed to last for a specified time with healthy margins. If one can do that without some capability that costs something in dollars or complexity or risk, then it's an impossible sell to add that. Solar panel self-cleaning, even if it was as easy as laypeople always seem to think, just doesn't make that cut.
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#322 by Blackstar on 01 Jan, 2023 13:44
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This. No spacecraft is designed to last indefinitely. They are designed to last for a specified time with healthy margins. If one can do that without some capability that costs something in dollars or complexity or risk, then it's an impossible sell to add that. Solar panel self-cleaning, even if it was as easy as laypeople always seem to think, just doesn't make that cut.
Yup, and not only is it an impossible sell, the designers don't want to even try making that sell. They're trying to keep the cost down below the cost cap for the program. That means they are designing to reach the mission lifetime (with safety margin) and no more. No mission proposer wants to get rejected because they added that one little thing to the mission that pushed them over the cost cap and resulted in some other proposer winning. They do all hope for much longer lifetimes, however.
Now there's a lot more that can be written about this subject, because many--not all--missions significantly exceed their design lifetimes. Years ago, I dealt with a NASA HQ guy who was convinced that this was because the designers were padding their missions and they could cut back, and reduce costs, so that they achieved the design lifetime and didn't exceed it by huge amounts. He was a former engineer for a three-letter agency, and he certainly knew more about this than I did, so I had to consult with a bunch of mission designers and ask them about that. Almost all of them disagreed with his premise. I don't remember why, but at least part of it is that for some spacecraft components, there's no way to select a specific mission lifetime once you get past a certain point.
I'm going to make up some numbers here, but it's something like this: you can design it to last 2 years with 95% confidence. And then you probably have 90% confidence that it will make it to 3 years, and 80% confidence that it will reach 4 years, and 70% confidence that it will reach 6 years. But for many things, there is no way to design it to 95% confidence for 2 years and then have it drop off radically so that it's only 50% at 3 years. If it works to the design life, it's probably going to keep working for a long time beyond that.
InSight lasted four years. It was designed for two. That's a pretty successful mission.
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#323 by Don2 on 14 Feb, 2023 06:46
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From 2023 LPSC abstracts about Insight:
1/ Collected 1319 Mars quakes and 8 meteoroid impacts. Largest quake magnitude was 4.7. 14 events have a complete location.
2/Seismicity is located in only a few spots around Mars, none close to Insight. Cerberus Fossae is the most active area, and there is evidence for active volcanic dykes there.
3/ There is seismic evidence for a liquid silicate layer at the bottom of the mantle. This would give a core smaller than the currently accepted radius of 1830km. The current radius gives a low core density which requires a large light element budget which is in excess of what is cosmochemically considered feasible. The new seismic analysis supports a smaller, denser liquid core made of Fe-Ni-S-C-O-H. This is consistent with the radio science data.
https://www.hou.usra.edu/meetings/lpsc2023/pdf/1448.pdf -
#324 by Blackstar on 27 Feb, 2023 18:08
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Listening to MEPAG meeting.
InSight is dead, but they are still listening for signals on a non-interference basis with other listening efforts, just in case a dust devil cleans it off and it powers up.
They were hoping for dust devils and expected them, but they did not occur.
The laser reflector is covered with dust but apparently still works. That could change if it gets more dust. -
#325 by Blackstar on 20 Mar, 2023 18:22
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https://link.springer.com/article/10.1007/s11214-023-00964-0
Special Communication
Open Access
Published: 20 March 2023
Results from InSight Robotic Arm Activities
M. Golombek, T. Hudson, P. Bailey, N. Balabanska, E. Marteau, C. Charalambous, M. Baker, M. Lemmon, B. White, R. D. Lorenz, T. Spohn, J. Maki, P. Kallemeyn, J. B. Garvin, C. Newman, K. Hurst, N. Murdoch, N. Williams, W. B. Banerdt, P. Lognonné, P. Delage, R. Lapeyre, E. Gaudin, C. Yana, …T. Gabsi
Space Science Reviews volume 219, Article number: 20 (2023) Cite this article
Abstract
The InSight lander carried an Instrument Deployment System (IDS) that included an Instrument Deployment Arm (IDA), scoop, five finger “claw” grapple, forearm-mounted Instrument Deployment Camera (IDC) requiring arm motion to image a target, and lander-mounted Instrument Context Camera (ICC), designed to image the workspace, and to place the instruments onto the surface. As originally proposed, the IDS included a previously built arm and flight spare black and white cameras and had no science objectives or requirements, or expectation to be used after instrument deployment (90 sols). During project development the detectors were upgraded to color, and it was recognized that the arm could be used to carry out a wide variety of activities that would enable both geology and physical properties investigations. During surface operations for two martian years, the IDA was used during major campaigns to image the surface around the lander, to deploy the instruments, to assist the mole in penetrating beneath the surface, to bury a portion of the seismometer tether, to clean dust from the solar arrays to increase power, and to conduct a surface geology investigation including soil mechanics and physical properties experiments. No other surface mission has engaged in such a sustained and varied campaign of arm and scoop activities directed at such a diverse suite of objectives. Images close to the surface and continuous meteorology measurements provided important constraints on the threshold friction wind speed needed to initiate aeolian saltation and surface creep. The IDA was used extensively for almost 22 months to assist the mole in penetrating into the subsurface. Soil was scraped into piles and dumped onto the seismometer tether six times in an attempt to bury the tether and ∼30%
was entrained in the wind and dispersed downwind 1-2 m, darkening the surface. Seven solar array cleaning experiments were conducted by dumping scoops of soil from 35 cm above the lander deck during periods of high wind that dispersed the sand onto the panels that kicked dust off of the panels into suspension in the atmosphere, thereby increasing the power by ∼15% during this period. Final IDA activities included an indentation experiment that used the IDA scoop to push on the ground to measure the plastic deformation of the soil that complemented soil mechanics measurements from scoop interactions with the surface, and two experiments in which SEIS measured the tilt from the arm pressing on the ground to derive near surface elastic properties.
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#326 by Comga on 20 Mar, 2023 20:27
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This. No spacecraft is designed to last indefinitely. They are designed to last for a specified time with healthy margins. If one can do that without some capability that costs something in dollars or complexity or risk, then it's an impossible sell to add that. Solar panel self-cleaning, even if it was as easy as laypeople always seem to think, just doesn't make that cut.
Yup, and not only is it an impossible sell, the designers don't want to even try making that sell. They're trying to keep the cost down below the cost cap for the program. That means they are designing to reach the mission lifetime (with safety margin) and no more. No mission proposer wants to get rejected because they added that one little thing to the mission that pushed them over the cost cap and resulted in some other proposer winning. They do all hope for much longer lifetimes, however.
(snip)
(my bolding)
That’s generally true for plebeian mission managers but this is JPL.
From the abstract for the Golumbek paper on Insight’s IDA/arm:QuoteDuring project development the detectors were upgraded to color, and it was recognized that the arm could be used to carry out a wide variety of activities that would enable both geology and physical properties investigations.
It seems highly unlikely that a color camera, which usually has half the resolution of the equivalent monochromatic camera, was really important to the science mission. And changing the sensor or building a new camera costs significant money.
Programs at JPL are pretty “forward leaning” when considering adding functions and hardware elements, and trying to hold JPL to cost caps is tough. (I know one person who lost his position attempting that, and someone at JPL who built a twenty man team to do much less well what he had done on a previous mission with two. Long stories)
This isn’t to say that we haven’t seen on occasion terrific results from JPL “mission creep”. It’s part of our Faustian bargain.
Suffice it to say, it wouldn’t have been that surprising if after considering the “wide variety of activities“ they could do, the Insight team had added a brush to the arm.
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#327 by russianhalo117 on 18 May, 2023 20:27
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#328 by Phil Stooke on 18 May, 2023 23:02
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"added a brush to the arm"
Brushing abrasive dust into the surface of a solar panel is not a wise move. Also the range of motion of the arm would almost certainly not even enable it to reach out over the panels. It was designed to work in a specific workspace. -
#329 by catdlr on 19 May, 2023 02:54
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#330 by ulm_atms on 28 May, 2023 23:36
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#331 by Hobbes-22 on 29 May, 2023 08:01
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I don't remember why, but at least part of it is that for some spacecraft components, there's no way to select a specific mission lifetime once you get past a certain point.
I'm going to make up some numbers here, but it's something like this: you can design it to last 2 years with 95% confidence. And then you probably have 90% confidence that it will make it to 3 years, and 80% confidence that it will reach 4 years, and 70% confidence that it will reach 6 years. But for many things, there is no way to design it to 95% confidence for 2 years and then have it drop off radically so that it's only 50% at 3 years. If it works to the design life, it's probably going to keep working for a long time beyond that.
InSight lasted four years. It was designed for two. That's a pretty successful mission.
Yep. This is a well-known observation in engineering: reliability tends to follow a bathtub curve. Components will either fail quickly after the device has been built, or they'll last for a long time before failing.
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#332 by FutureSpaceTourist on 19 Aug, 2023 20:24
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https://twitter.com/haygenwarren/status/1692967513577947216Quote
Although its mission ended in December, data from NASA’s InSight lander is allowing scientists to continue making new discoveries about Mars.
In fact, one team of scientists recently discovered that Mars’ rotational speed is accelerating ⬇️
https://www.nasaspaceflight.com/2023/08/insight-rise/ -
#333 by Star One on 19 Oct, 2023 16:21
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Quote
The strongest-ever quake to violently shake Mars arose not because of a crashing asteroidbut rather the tectonic forces within the planet itself, scientists reported on Tuesday (Oct. 17). The new findings show the Red Planet is more seismically active than previously thought.
On May 4, 2022, NASA's now-retired InSight lander recorded a magnitude 4.7 quake, five times stronger than the previous record holder of magnitude 4.2 that InSight measured in 2021. Unlike most marsquakes that cease within an hour, the reverberations from the May 2022 quake continued for a record six hours, marking the strongest and longest quake ever recorded on another planet.
https://www.livescience.com/space/mars/strongest-and-longest-marsquake-ever-detected-finally-has-an-explanation
Related paper:
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2023GL103619 -
#334 by FutureSpaceTourist on 23 Oct, 2023 03:29
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https://twitter.com/haygenwarren/status/1716194597922070578Quote
A team of scientists has found the source of the largest Marsquake observed by NASA’s InSight lander. The team concluded the quake must have been caused by a release of stress within the planet’s crust.
Martijn Luinstra’s debut article for NSF ⬇️
https://www.nasaspaceflight.com/2023/10/s1222a-origins/ -
#335 by Star One on 25 Oct, 2023 19:00
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Quote
The core of Mars can look bigger than it actually is because of a previously unknown layer of molten rock surrounding it, scientists suggest with a pair of new studies.
…QuoteSince the 2021 studies appeared, InSight detected more Martian seismic waves, produced by a meteorite impact on Mars far away from the lander. "The impact produced a lot of energy, generating seismic waves that traversed the core of Mars," Khan said. "Up until then, we didn't have any of those to examine. They allowed us to gain a completely new picture of the interior of Mars, especially deep structures that we couldn't illuminate before."
Two new studies now estimate the center of Mars is about 2,050 to 2,080 miles (3,300 to 3,350 km) in diameter. All in all, the Martian core "is 30 percent smaller in volume than previous estimates," Henri Samuel, a planetary dynamicist at Paris Cité University in France, told Space.com.
https://www.space.com/mars-core-molten-silicon-rock
Related papers:
https://www.nature.com/articles/s41586-023-06586-4
https://www.nature.com/articles/s41586-023-06601-8 -
#336 by Kaputnik on 05 Mar, 2024 23:54
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The laser reflector is covered with dust but apparently still works. That could change if it gets more dust.
Can the amount of dust covering the reflector be reasonably estimated from the return signal? Or is it more of a case of you either see it, or you don't? -
#337 by FutureSpaceTourist on 08 Jul, 2024 06:38
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https://twitter.com/haygenwarren/status/1810083909171863913Quote
Scientists have calculated the rate of meteoroid impacts on Mars using seismic measurements from NASA’s retired InSight lander. Two new studies estimate much higher impact rates than were previously derived from orbital spacecraft.
By Martijn Luinstra ⬇️
https://www.nasaspaceflight.com/2024/07/insight-meteoroid-impact-rate/ -
#338 by Dalhousie on 08 Jul, 2024 22:46
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https://twitter.com/haygenwarren/status/1810083909171863913
QuoteScientists have calculated the rate of meteoroid impacts on Mars using seismic measurements from NASA’s retired InSight lander. Two new studies estimate much higher impact rates than were previously derived from orbital spacecraft.
By Martijn Luinstra ⬇️
https://www.nasaspaceflight.com/2024/07/insight-meteoroid-impact-rate/
“This size impact, we would expect to happen maybe once every couple of decades, maybe even once in a lifetime, but here we have two of them that are just over 90 days apart,” Daubar said. “It could just be a crazy coincidence, but there’s a really, really small likelihood that it’s just coincidence. What’s more likely is that either the two big impacts are related, or the impact rate is a lot higher for Mars than what we thought it was.”
That assumption seems like a very elementary statistical error.
