Non-SpaceX Specific Exploration Missions Discussion

[JB47394]

Awesome it flew for 3 yrs, when it was only planned for a matter of weeks...

Yeah, but that's pretty standard for NASA hardware. They build them for robustness, and then they run them until they're dead. It's expensive to get these machines out there. ♪ ♪ Though prices may be falling soon. ♪ ♪

 

[scaesare]

Yeah, but that's pretty standard for NASA hardware. They build them for robustness, and then they run them until they're dead. It's expensive to get these machines out there. ♪ ♪ Though prices may be falling soon. ♪ ♪

Speaking of which, I'm still bummed it's been 6 weeks since the Voyager 1 issue, and still no news of a fix... actually no news at all... but these things can take time if they manage to be successful...

 

[Electroman]

Ingenuity: Planned for 5 flights.. ... flew 75 flights

 

[ecarfan]

NASA/JPL have really got their Mars exploration vehicles dialed in.

Perseverance landed February 2021 and is going strong almost 3 years later. I won’t be surprised to see it still operational 10 years from now.

Curiosity landed August 2012 for a planned 2 year mission and is still operating over 11 years later. Wow.

Spirit and Opportunity landed in January 2004 and were designed to last just 3 months. Opportunity lasted nearly 15 years. Spirit got stuck in sand after 5 years and then went almost another 2 years stationary but still doing science before communications stopped.

Incredible track record. Rocket scientists rock!

 

[ecarfan]

Eric Berger: It turns out NASA’s Mars helicopter was much more revolutionary than we knew

the RAD750 computer that operates most modern spacecraft—including the Perseverance rover—weighs more than 1 pound. They couldn't blow that much mass on the computer, even if it was designed specifically for spaceflight and was resistant to radiation…Ingenuity uses a 2015-era smartphone computer chip, a Qualcomm Snapdragon 801 processor. It has a mass of half an ounce.

The RAD750 costs a quarter million dollars. Obviously, the Snapdragon 801 costs almost nothing in comparison.

"The processor on Ingenuity is 100 times more powerful than everything JPL has sent into deep space, combined," Tzanetos said. This means that if you add up all of the computing power that has flown on NASA's big missions beyond Earth orbit, from Voyager to Juno to Cassini to the James Webb Space Telescope, the tiny chip on Ingenuity packs more than 100 times the performance.

Also obviously, the Snapdragon 801 is not radiation hardened yet it performed just fine.

A similar philosophy went into other components, such as the rechargeable batteries on board. These are similar to the lithium batteries sold in power tools at hardware stores. Lithium hates temperature cycles, and on the surface of Mars, they would be put through a hellish cycle of temperatures from -130° Fahrenheit (-90° C) to 70° (20° C). The miracle of Ingenuity is that all of these commercially bought, off-the-shelf components worked. Radiation didn't fry the Qualcomm computer. The brutal thermal cycles didn't destroy the battery's storage capacity. Likewise, the avionics, sensors, and cameras all survived despite not being procured with spaceflight-rated mandates.

 

[scaesare]

Eric Berger: It turns out NASA’s Mars helicopter was much more revolutionary than we knew

The RAD750 costs a quarter million dollars. Obviously, the Snapdragon 801 costs almost nothing in comparison.


Also obviously, the Snapdragon 801 is not radiation hardened yet it performed just fine.

This is going to make a lot of NASA suppliers of $8,000 washers a little miffed.

I also seem to recall that SpaceX used off-the-shelf computer motherboards at one point, and just made a nice aluminum enclosure for them...

 

[JB47394]

This is going to make a lot of NASA suppliers of $8,000 washers a little miffed.

Or cause them to hire more lobbyists. Keep the cost of aerospace high so that any failure is unacceptable. That means that the components must be extremely reliable. That means that they're going to cost more. That means the cost of aerospace is higher. That means that any failure is even more unacceptable. And so on. The tyranny of the rocket equation simpleminded caution.

I also seem to recall that SpaceX used off-the-shelf computer motherboards at one point, and just made a nice aluminum enclosure for them...

My chatbot led me to this page, which has lots of details on Falcon 9 from 2012.

What Hardware/Software Does SpaceX Use To Power Its Rockets? - RankRed

SpaceX vehicles are powered by dual core x86 processors. In addition to Linux operating system, they use LabView, a graphical programming tool that runs on Windows. The programmers at SpaceX prefer using C++ (and sometimes Python). The vehicle code is on the order of a couple of hundred thousand...

www.rankred.com

As you said, they're relying on redundancy from many conventional processors. They're light and cheap, so the greatest challenge is in configuring everything to detect and handle failures. NASA has been moving away from radiation hardening and towards this "radiation tolerant" approach for some uses.

 

[JB47394]

The JAXA SLIM lunar lander mission got within 55m of its targeted landing location, which is amazingly good, but unfortunately during final descent, at 50m above the surface one of its two engines lost power and the lander ended up on its side. That means its solar panels won’t generate enough power to keep it going. It was able to deploy two small probes and one of them returned this photo. Oops!

Apparently the sun has swung around enough for the solar panels to get some power. JAXA says they're back to doing science.

Moon lander: Japan's Slim reactivates and gets to work

The reawakened craft has begun detailed analysis of the lunar surface including nearby rocks

www.bbc.com

 

[Grendal]

 

[scaesare]

Or cause them to hire more lobbyists. Keep the cost of aerospace high so that any failure is unacceptable. That means that the components must be extremely reliable. That means that they're going to cost more. That means the cost of aerospace is higher. That means that any failure is even more unacceptable. And so on. The tyranny of the rocket equation simpleminded caution.


My chatbot led me to this page, which has lots of details on Falcon 9 from 2012.

What Hardware/Software Does SpaceX Use To Power Its Rockets? - RankRed

SpaceX vehicles are powered by dual core x86 processors. In addition to Linux operating system, they use LabView, a graphical programming tool that runs on Windows. The programmers at SpaceX prefer using C++ (and sometimes Python). The vehicle code is on the order of a couple of hundred thousand...

www.rankred.com

As you said, they're relying on redundancy from many conventional processors. They're light and cheap, so the greatest challenge is in configuring everything to detect and handle failures. NASA has been moving away from radiation hardening and towards this "radiation tolerant" approach for some uses.

Ah yeah... redundancy of inexpensive components as a course for reliability and resiliency has proved to be a great approach in many areas...

 

[bxr140]

This is going to make a lot of NASA suppliers of $8,000 washers a little miffed.

Tounge-in-cheek noted, there's really not a lot of margin in space parts. Generally they're so expensive because the purchaser wants to be hyper confident that piece is going to do what it needs to do. The cost goes astronomical (bah-dum) because of things like:

• Significant nondestructive and destructive testing (sometimes 20% of a lot is set aside for lot testing...or even more)
• Really low lot volumes (hundreds or thousands of parts instead of tens of thousands or more), so much higher per-part non-recurring costs (setup, etc.)
• Full traceability from material orgin through final installation location and everything in-between

While some space parts are indeed "better" than equivalent lower grade parts (automotive, etc.) due to things like tighter tolerances or uprated materials, the irony of many space parts (typically less important ones) is that they are literally the same thing as lower grade parts made on the same machines as the lower grade parts...just in way smaller runs. Part of the general COTS philosophy is that whatever you're losing by not doing significant lot testing or traceability exercises, you gain in sheer statistics--the variation in a COTS lot that's orders of magnitude bigger than a space lot is often way more favorable for the end user.

Maybe a little adjacent, and I've probably posted this before, but on the subject of parts selection Doug (basically one of the pioneers in 'volume' smallsat components) and Jonny (formerly the CTO of Skybox and one of the founders of Muon) wrote a paper a while back that a lot of folks still use as guidelines.

I also seem to recall that SpaceX used off-the-shelf computer motherboards at one point, and just made a nice aluminum enclosure for them...

Yeah, especially in low LEO (and a very short life), you really don't need a ton of tolerance for even the really important parts. A combination of shielding and redundancy is really all that's required. Shielding also doesn't need to be dedicated or fully enclosing either--it is more or less additive. Any bits and pieces that might 'block' your important components from those pesky particles count as shielding. One of the things you do toward the end of a satellite design is ray tracing from the important components to understand what physical directions of dosage are actually untolerable. Then you might only need to put a block of shielding on one side of that processor, or maybe to slide that reaction wheel (that is mostly a big block of aluminum anyway) a bit this way or that to provide "free" shielding.


In context, the Snapdragon on Ingenuity actually checks out. Mind, I'm sure it made the old guard go head-explody for a while in Pasadena, but if one actually evaluates the use case it's not some giant leap:

• It had a pretty short life in a radiation environment. Even though space and Mars is, of course, much harsher than LEO from a radiation perspective, its fair to assume Ingenuity was pretty well shielded during the transfer to mars and then also reasonably well shielded sitting on the surface of Mars (half the time not facing the sun). The major upside here is that permanent damage due to total dose would have been minimal (and likely a non-issue).
• In addition to what was likely some component redundancy to mitigate the effects of upsets, the inherently short mission duration of each flight would statistically minimize the possibility of some kind of single event actually happening during flight. No doubt the startup sequence scrubbed/reset the important chips prior to liftoff, so basically all the the processor (and other important/susceptible components) had to do was stay clean for a 1-2 minute flight.

 

[scaesare]

Tounge-in-cheek noted, there's really not a lot of margin in space parts. Generally they're so expensive because the purchaser wants to be hyper confident that piece is going to do what it needs to do. The cost goes astronomical (bah-dum) because of things like:

• Significant nondestructive and destructive testing (sometimes 20% of a lot is set aside for lot testing...or even more)
• Really low lot volumes (hundreds or thousands of parts instead of tens of thousands or more), so much higher per-part non-recurring costs (setup, etc.)
• Full traceability from material orgin through final installation location and everything in-between

While some space parts are indeed "better" than equivalent lower grade parts (automotive, etc.) due to things like tighter tolerances or uprated materials, the irony of many space parts (typically less important ones) is that they are literally the same thing as lower grade parts made on the same machines as the lower grade parts...just in way smaller runs. Part of the general COTS philosophy is that whatever you're losing by not doing significant lot testing or traceability exercises, you gain in sheer statistics--the variation in a COTS lot that's orders of magnitude bigger than a space lot is often way more favorable for the end user.

Maybe a little adjacent, and I've probably posted this before, but on the subject of parts selection Doug (basically one of the pioneers in 'volume' smallsat components) and Jonny (formerly the CTO of Skybox and one of the founders of Muon) wrote a paper a while back that a lot of folks still use as guidelines.



Yeah, especially in low LEO (and a very short life), you really don't need a ton of tolerance for even the really important parts. A combination of shielding and redundancy is really all that's required. Shielding also doesn't need to be dedicated or fully enclosing either--it is more or less additive. Any bits and pieces that might 'block' your important components from those pesky particles count as shielding. One of the things you do toward the end of a satellite design is ray tracing from the important components to understand what physical directions of dosage are actually untolerable. Then you might only need to put a block of shielding on one side of that processor, or maybe to slide that reaction wheel (that is mostly a big block of aluminum anyway) a bit this way or that to provide "free" shielding.


In context, the Snapdragon on Ingenuity actually checks out. Mind, I'm sure it made the old guard go head-explody for a while in Pasadena, but if one actually evaluates the use case it's not some giant leap:

• It had a pretty short life in a radiation environment. Even though space and Mars is, of course, much harsher than LEO from a radiation perspective, its fair to assume Ingenuity was pretty well shielded during the transfer to mars and then also reasonably well shielded sitting on the surface of Mars (half the time not facing the sun). The major upside here is that permanent damage due to total dose would have been minimal (and likely a non-issue).
• In addition to what was likely some component redundancy to mitigate the effects of upsets, the inherently short mission duration of each flight would statistically minimize the possibility of some kind of single event actually happening during flight. No doubt the startup sequence scrubbed/reset the important chips prior to liftoff, so basically all the the processor (and other important/susceptible components) had to do was stay clean for a 1-2 minute flight.

Yeah, I assume design considerations for short duration LEO vs long geo or deep space missions are a couple of order of magnitude more in-depth...

Thanks for the paper, I just skimmed, and the conclusion makes the point their approach allows them to eliminate the need for some aspects of shielding & test:

I wonder what the Voyagers have on them for radiation shielding, and if that's what caused Voyager 1's current problem...

 

[JB47394]

I wonder what the Voyagers have on them for radiation shielding, and if that's what caused Voyager 1's current problem...

All you could possibly want to know.

Voyager Electronic Parts Radiation Program Volume I: Final Report

I started skimming the report, but it's a combination of technical and bureaucratic text, with lots of information on how they tested everything. I tried searching for "aluminum", "styrene", "wrap", "box", "enclosure" and just couldn't find what they actually did to protect the components. I know that the components that the probes carried were radiation hardened. Perhaps that was their main focus.

From page 4-4:

Most of the potential problems with the Voyager electronics are due to long-term ionizing radiation effects. In semiconductor devices these are manifestations of charges trapped in insulating layers on the surfaces of the semiconductor devices. These are most important in MOS structures in which trapped charge in the gate oxide layer produces a first-order change in the apparent gate voltage. Trapped charge in surface passivation layers is also important in junction devices, where it produces an inversion layer that spreads out the effective surface area, thereby increasing recombination-generation currents. These currents are most important in bipolar transistors operated at low collector currents and in n-channel JFET devices. The susceptibility to charging depends on the quality of the oxide layer and is not usually consciously controlled in semiconductor device manufacturing.

One funny thing about Voyager shielding is that they realized that the radiation and magnetic fields would be stronger then they originally designed and tested for. To address the problem, they took strips of kitchen-grade aluminum foil and wrapped some of the cabling. This happened in the last few months before launch.

 

[scaesare]

All you could possibly want to know.

Voyager Electronic Parts Radiation Program Volume I: Final Report

I started skimming the report, but it's a combination of technical and bureaucratic text, with lots of information on how they tested everything. I tried searching for "aluminum", "styrene", "wrap", "box", "enclosure" and just couldn't find what they actually did to protect the components. I know that the components that the probes carried were radiation hardened. Perhaps that was their main focus.

From page 4-4:


One funny thing about Voyager shielding is that they realized that the radiation and magnetic fields would be stronger then they originally designed and tested for. To address the problem, they took strips of kitchen-grade aluminum foil and wrapped some of the cabling. This happened in the last few months before launch.

Cool... I suspect I'll read more of that than I really have time for, lol...

See?? Tin-foil hats may actually be effective after all!

 

[bxr140]

I wonder what the Voyagers have on them for radiation shielding, and if that's what caused Voyager 1's current problem...

In addition to what's above, it's worth noting that radiation tolerance generally goes down with advancing technology. The physical size of old school electronics makes them inherently more tolerant than the tight packaging of today's tech. For instance, for the same size old vs new component you're getting the same overall dosage (of course), but the radiation is impacting orders and orders of magnitude fewer transistors (or whatever) on the old tech and there's orders and orders of magnitude more space in-between those transitors through which a particle can pass right through without doing damage.

One funny thing about Voyager shielding is that they realized that the radiation and magnetic fields would be stronger then they originally designed and tested for. To address the problem, they took strips of kitchen-grade aluminum foil and wrapped some of the cabling. This happened in the last few months before launch.

Reynolds Wrap is a common material in test chambers...but not so much flight hardware...

These days space grade foil is where its at.
(There's plenty of it still, usually used to complete the faraday cage, but its typically much thicker than what's in your cupboard)

 

[scaesare]

In addition to what's above, it's worth noting that radiation tolerance generally goes down with advancing technology. The physical size of old school electronics makes them inherently more tolerant than the tight packaging of today's tech. For instance, for the same size old vs new component you're getting the same overall dosage (of course), but the radiation is impacting orders and orders of magnitude fewer transistors (or whatever) on the old tech and there's orders and orders of magnitude more space in-between those transitors through which a particle can pass right through without doing damage.

Makes sense... as feature size goes down, there are lots of things that have a greater impact: contamination, cosmic rays, etc...

 

[ecarfan]

Eric Berger: For the first time NASA has asked industry about private missions to Mars

This week, the space agency's Jet Propulsion Laboratory issued a new solicitation to the industry titled "Exploring Mars Together: Commercial Services Studies." This is a request for proposals from the US space industry to tell NASA how they would complete one of four private missions to Mars, including delivering small satellites into orbit or providing imaging services around the red planet.
"The Mars Exploration Program Draft Plan through the next two decades would utilize more frequent lower cost missions to achieve compelling science and exploration for a larger community," the document states. "To realize the goals of the plan, government and US industry would partner to leverage current and emerging Earth and lunar products and commercial services to substantially lower the overall cost and accelerate leadership in deep space exploration."

NASA outlines 4 possible mission types, and this one seems a good fit for SpaceX, since its going to do this anyway:

• Next-generation relay services: Provide communications relay services between Mars and Earth for surface and orbital assets for four years.

But the money NASA is offering is only “$200,000 for a study of one of the reference missions or $300,000 for a maximum of two studies” so maybe it’s not worth it to SpaceX.

 

[scaesare]

Eric Berger: For the first time NASA has asked industry about private missions to Mars

NASA outlines 4 possible mission types, and this one seems a good fit for SpaceX, since its going to do this anyway:

But the money NASA is offering is only “$200,000 for a study of one of the reference missions or $300,000 for a maximum of two studies” so maybe it’s not worth it to SpaceX.

Reading about, and listening to Elon Talk about, his disappointment that NASA had no Mars plans even on the table back in the day, and his subsequent decision to it himself, I kinda feel like this legitimizes at the gov't level what he been aiming for over the last couple of decades. Even if the money is not much, I suspect symbolically SpaceX would be all about wanting to cooperate...

 

[scaesare]

Also, interesting white paper written by some folks participating in "Mars Workshops" (partially funded by SpaceX) that may have helped prompt NASA to do this...

 

[JB47394]

Reading about, and listening to Elon Talk about, his disappointment that NASA had no Mars plans even on the table back in the day

Elon certainly isn't the first to come up with a plan to go to Mars. He's just the first to have the technology and resources to do it. The last 60 years are pretty clear in establishing that the US government has no interest in space. There are no new votes to be found there.

List of crewed Mars mission plans - Wikipedia

en.wikipedia.org

I doubt I'm in the minority when I say that SpaceX represents the correct way to pursue spaceflight. When the nation is ready to go, it'll go. It shouldn't be mandated by politicians because they'll do it for non-viable reasons. Political reasons. It's socialized spaceflight.

Also, interesting white paper written by some folks participating in "Mars Workshops" (partially funded by SpaceX) that may have helped prompt NASA to do this...

Why won't these people put dates on their publications? They cite works from 2019, so I'm assuming it's contemporary to those.

I can only imagine the excitement these days in NASA and elsewhere as they watch Starship development progress.