Mars InSight lander

Void · 2019-03-05 11:18:57

It appears that it will take some time to get their thermal probe set up.

https://www.scientificamerican.com/arti … -is-rough/

But I have to believe that they made it work under adverse conditions on Earth.

Done.

elderflower · 2019-03-05 14:27:17

That may indicate better ground bearing capacity than we have supposed so far in other threads. In one spot, at least.

GW Johnson · 2019-03-06 13:06:58

Based on the news reports in various places, it looks to me like they ran into a big underground rock. Too big for the hammered probe to slide around. Seems to be a surprise to them.

I find it not at all surprising to learn there are big rocks interspersed among small rocks and gravel, in the regolith of a planet cratered by impacts. Like the moon.

I'd bet real money the possibility of big buried rocks getting in the way was not part of the design process and development testing for the thermal probe experiment. Although it should have been.

They probably used sand mixed with smallish gravel, packed tight, with some water chemistry-mediated cementation to it. Whatever the Mars soil surrogate has been.

I've been telling everyone for some time now that real ground truth is always at variance with expectations before you go there. Looks like that's true subsurface as well as on the surface. Which is not at all surprising to me.

As for that indicating better surface bearing qualities for landings and takeoffs, we don't know that. Seems foolish to bet lives on an unknown, doesn't it? Plan on something resembling "smooth, loose, fine sand", which the bulk of Mars seems to resemble, when seen up close. The polar permafrost is harder, but that's not where we will land.

GW

Last edited by GW Johnson (2019-03-06 13:10:21)

SpaceNut · 2019-03-06 17:34:40

Good reason to send more of them to do more testing of any sights that we would want to land on mars in order to set up shop to explore for the first site to land at.
It might not be the BFR but its going to be something at sometime in the future.

elderflower · 2019-03-07 10:38:10

Any big civil engineering project on earth will do a site survey, including boreholes and test piles where appropriate, to establish the nature and bearing capacities of soils and bedrock and the groundwater conditions. I do recall a couple of projects that skipped this step, relying on geological maps instead, on one of which an acquaintance made a major fortune hauling aggregate for concrete to overcome the deficiency of the site that the work had revealed. On the second somebody must have made another fortune hauling rock to infill ancient mining galleries which weren't on the maps and were discovered by the rapid disappearance of piles.
These same precautions must be taken by a pioneering group on Mars before we start sending large and heavy expeditions. I'm not suggesting that there are old mines up there, but other subterranean features like infilled channels, lava tubes or kettle holes may be present as well as big boulders. we could probably deliver the needful equipment and half a dozen humans to Mars with 3 or 4 Falcon heavy flights and modified Dragons for the people. then a couple more for return requirements.

Last edited by elderflower (2019-03-07 10:42:18)

GW Johnson · 2019-03-07 12:12:54

What you say about soil bearing testing is all true, except for getting any humans to Mars riding in a space capsule, Dragon or other (including Orion). That trip is nominally 8.5 months on a min energy trajectory, and still 6 months if you can afford the delta-vee to fly faster.

With room to get in and out of space suits, and to pee and poop into plastic bags, a crew of 3 could deal with 2 weeks in an Apollo capsule. With the room to even straighten legs and "doing it in the suit", a Gemini crew (Gemini 7) survived 2 weeks, but were cracking up (2 weeks was early return, the mission was for up to 3 weeks). That's something not at all publicized by NASA, but you can find it if you look hard enough.

Point is, tight confinement drives people crazy. Seriously crazy. The tighter the confinement the sooner the crazy happens, and the more intense the crazy is. Regardless of what you look at, the timeline to go crazy is weeks, not months, regardless of whose capsule design you consider.

And once you get to Mars, you are still confined, because you cannot go outside without a suit, and the gas balloon suits are extremely confining. There is no real relief. Not until there is a settlement with big buildings to roam around in.

OK, now 3 guys in something like a Skylab workshop or bigger can last months at a time. We proved that with the Skylab mission, the Russians with Mir, and now we all together with ISS. That's 100+ cubic meters volume per person, and that is no space capsule!

I think I just told you one of the reasons that Spacex's BFS Starship is so big inside its habitable space, bigger than a widebody airliner, while carrying only 100 people at most to Mars. That's still a bot tight: under 100 cubic meters per person. If you fly 100 people, there had better be confinement relief when they reach Mars.

There, I just gave you a very serious constraint on how many and how soon, for any Spacex-delivered settlement. The others with their smaller vehicles will necessarily take even longer.

GW

kbd512 · 2019-03-07 12:42:51

GW,

Actually, I think you just explained why it is that we need far larger MTV's than Starship. These things need to be space station size vehicles with even more habitable volume and AG. Some semblance of normalcy is required for most people. I disagree that everyone will go crazy in two weeks in a capsule. Most people will go crazy. Some will not. The belief that military training prevents people from acting irrationally because they're uncomfortable for some period of time is also wrong. That is why special forces training spares no effort to make people uncomfortable. It's to find out who will ignore their temporary personal discomfort, or even excruciating pain, and press on with the mission. You'll get far fewer volunteers and fewer still who make it through the training, but the intended purpose of the training is not to push people through who can't do what the job requires.

SpaceNut · 2019-03-07 22:00:48

Yes large ITV and small lander to allow for setting up a site for the much larger lander that will follow once site surveys and prep are done.

elderflower · 2019-03-08 03:42:49

So your large ITV remains in orbit because we don't know where we can land it. Capsule deorbits take crews to the surface, with equipment to check out sites for suitability. Capsules can hop or return to orbit to try again somewhere else.
Perhaps a robot tanker visits the surface to convert CO2 to LOX and returns the LOX to orbit, then you only need to carry the ITV's deorbit/ landing or return fuel and the capsules' exploration fuel to Mars, oxidiser being a much larger mass than the fuel. The LOX supply would need a separate mission to ensure it is available in orbit before the ITV is committed to it's trip.
Maybe capsules could use CO/LOX engines for ascent and hopping as these can be made easily on Mars by equipment to be carried on the capsules, given sufficient power, and even in the absence of usable water. I don't suppose that this fuel would be suitable for the ITV, but for hopping and ascent from the surface the relatively low Isp wouldn't be prohibitive.

Last edited by elderflower (2019-03-08 03:53:24)

kbd512 · 2019-03-08 09:43:27

Elderflower,

Seems like a good combo to me if we're using pump-fed engines. All we need is Martian atmosphere and electrical power. At 3,000psi, LOX/LCO specific impulse is basically equivalent to LOX/LCH4 sea-level performance.

Carbon Monoxide and Oxygen Combustion Experiments: A Demonstration of Mars In Situ Propellants

This study seems to indicate that we'd require 27% less electrical power, too. At some point, the total mass and complexity of all systems required to make this a reality should be considered. LOX/LCO is low-risk compared to the non-existent LCH4 plant and ice mining equipment we'd need to make a LCH4-fueled rocket / lander work. The Isp increase is nice, but not if it means that we just negate all of that with increased infrastructure mass required to provide the infrastructure to produce propellant. LOX and LCO can be made using existing technology, so R&D costs would also be lower. In the future, we could always switch to LOX/LCH4 after we find the ice, determine how to mine it, and how to build a LCH4 plant that works on Mars.

A Comparison of Preliminary Design Concepts for Liquid, Solid and Hybrid Propelled Mars Ascent Vehicles Using In-Situ Propellants

I think the Rutherford engine tech from Electron Labs that sucks the tanks dry and using battery-powered electrical turbo pumps is worth a look. There are no propellant residuals to prevent the turbo pumps from exploding, unlike gas generators or staged combustion, and electrical control over the pumps for deep throttling. Just like staged combustion, all the propellant goes through the combustion chamber after it's been used to regeneratively cool the combustion chamber. The engines are so small and light that they're human-portable on Earth.

SpaceNut · 2019-03-08 18:39:25

Thanks for the post kbd512 and its been copied to the insitu fuels topic. We are sort of drifting but nice find.

SpaceNut · 2019-03-08 19:31:30

Bad insight Bad you are in time out or at the least the engineers are thinking about how to solve the problem.

Mars InSight Lander's 'Mole' Pauses Digging

mars-insight-heat-probe-heat-and-physical-properties-package-hp3-hg.jpg

Data show that the probe itself continues to function as expected: After heating by 50 degrees Fahrenheit (28 degrees Celsius), it measures how quickly that heat dissipates in the soil. The team will be conducting further heating tests this week to measure the thermal conductivity of the upper surface. They will also use a radiometer on InSight's deck to measure temperature changes on the surface. Mars' moon Phobos will pass in front of the Sun several times this week; like a cloud passing overhead, the eclipse will darken and cool the ground around InSight.

GW Johnson · 2019-03-09 14:51:02

As I thought, the news story you linked says the team did not plan on there being any big rocks underground.

On Mars? A planet covered by impact craters the way the moon is? And there are big rocks interspersed with smaller debris all over the moon? Really?

That idiotic design choice ranks right up there with aluminum tires on Curiosity, knowing there were sharp rock shards all over Mars.

GW

SpaceNut · 2019-03-09 22:15:56

All the more reason that any crews going to mars need to use a small landing mass so as to scout out the actual topology of the site before something larger is allowed to land.

tahanson43206 · 2019-03-15 17:48:53

Weather Reports from Mars: A local writer's view

The article at the link below may be visible to those in the NewMars audience who have not previously connected to the news site.

The column is by Joe Blundo, the title is: Earth to Mars: Get ready for guests, and it opens: "Dear Mars, Watch out. We've got our eyes on you"

https://www.dispatch.com/entertainmentl … use-guests

(th)

GW Johnson · 2019-03-17 10:07:49

I haven't seen any detailed news about this probe for a while. Did they ever get their probe hammered past that (unexpected) underground rock?

GW

SpaceNut · 2019-04-23 22:35:51

Earth quakes, moon quakes and now NASA probe detects likely 'marsquake' - an interplanetary first; NASA’s robotic probe InSight has detected and measured what scientists believe to be a “marsquake,” marking the first time a likely

SpaceNut · 2019-04-24 16:22:05

I would have thought that others might have spoke up about the fact that the seizmic unit worked and that we might find a core that is not stone cold. To which did the planet belch out any methane events during that same time frame. Not sure that any articles meantion how strong the quake was or about its depth to which it came from.

If its not stone cold then maybe someday we can get it moving to make a magnetic field as earths does.

Void · 2019-04-24 18:11:04

SpaceNut said:

I would have thought that others might have spoke up about the fact that the seizmic unit worked and that we might find a core that is not stone cold. To which did the planet belch out any methane events during that same time frame. Not sure that any articles meantion how strong the quake was or about its depth to which it came from.
If its not stone cold then maybe someday we can get it moving to make a magnetic field as earths does.

Well, I did see that article. I sometimes forget or leave it to others. Very encouraging news I feel.

I think that for now I can speculate on 3 models for Mars, but nature may throw us a curve ball, and surprise us with something unexpected.

For now, what I expect is;

-Mars completely solid? Well the quake suggests no. Also, Mercury, and Luna have partial liquid cores it is believed, and we think that Venus is also volcanic. I have trouble understanding why Mars would be completely solid. But that is not to say that somehow it is. We don't really know. Or;
-Mars is just now stating to move into tectonic action. There is at least one scientist who thinks so. I am not yet inclined to think so. But again, what would I know? Or;

Most objects like Mercury, Venus, Luna, and perhaps Mars, have partial liquid cores that do not cause tectonic action similar to Earth, because they are stratified. They therefore are heat traps, stingy with release of heat, not like Earth which is rather a hussy about releasing heat. Of course there is also the possibility that indeed if Luna was created by a Mars sized impactor, then somehow that sets Earth as unique. But I think that Earth is in a "Goldilocks" zone for tectonic movement. It has the right mix of materials, and the right temperature in its crust.

For Venus, I speculate that the crust is too hot to submerge. For Mars, I speculate that the crust is to buoyant to submerge. Both by being of a greater amount of less dense materials and by being filled so some extent with voids. Porous, due to a low gravity.

But I might be completely wrong, which rather than humiliating me will teach me that I have adjustments to make in my model of reality.

From my point of view, I want Mercury, Luna, and Mars to be stratified and hotter than expected. Therefore if that proves true, we may harvest the energy of geothermal power. For Mars especially that would be a grand gift.

As for Magnetic fields, I would not at this time be obsessive about it. I think that artificial ones can be created, and to be honest, I think the whole notion of Mars and Venus loosing their atmospheres to the solar wind can only be partially supported. I think that for Mars a significant loss of atmosphere would have been raging rivers and sediments locking the atmosphere into solids.

But we need to learn so much more.

Done.

Last edited by Void (2019-04-24 18:21:11)

elderflower · 2019-04-30 10:03:37

Quakes could occur on a solid planet due to surface activity such as cave collapse or landslips. I believe it is possible to eliminate impact signals but I don't know about collapses of cliffs or of Voids (sorry!).

Void · 2019-04-30 12:59:27

I am void of bad feelings and smile a bit.

I hate to jump in where my expertise is only having read a few articles. Very good chances others are superior in knowledge for this.

But I can say what I believe to possibly be true.

My understanding is that now they believe that both Mercury and Luna have partial liquid cores.

So if I had to flip a coin to save my life, I would venture that Mars more likely will have similar. A large solid core surrounded by a liquid core.

But that remains to be proven.

What I have read is that the quake they think they recorded resembles a Moon quake, and not an Earthquake. They are expecting that eventually they will see a quake 50 times as powerful. So for now the quake offers a hint of a Moon-like core.

They have said that for objects like this the interior can contract or expand, and eventually the crust snaps, and so that creates the Moon quake or perhaps in this case a Mars quake. Most lava tubes are very old, I would think that if they were going to collapse, it would be somewhat unlikely that we would show up for the event with Insight.

But it is good that you offered another possible source of the rumble. There definitely should not be imposed an orthodoxy about what is real for this phenomenon. For me it is second or more hand read information, and I do not consider myself to be of a vast wisdom.

Done.

Last edited by Void (2019-04-30 13:07:57)

SpaceNut · 2019-04-30 17:41:54

The moon is keeping a semi molten core as a result of the earth to which it orbits as the tidal forces will be mirrored on the moon that we see on earth.
The moons of mars I think are to small to make that sort of analysis for it having the same mechanism keeping it hot.

Void · 2019-04-30 18:47:20

You may prove correct. However Mercury, about the same size but otherwise of a much different nature seems to have a partial liquid core.

I think one of the tricks of insight will be to monitor its wiggle waggle properties as per the crust slipping slightly. That location identification supposedly, I think is intended to give evidence of a total solid core or of a remnant liquid core. We will hope to find out.

Done.

Last edited by Void (2019-04-30 18:47:41)

SpaceNut · 2019-05-01 21:11:54

A view from another planets as seen by Insight mission catches Sun rise and Sun set

GW Johnson · 2019-05-15 16:47:49

I finally saw a news clip today indicating that Insight's thermal probe is still only 30 cm down, where it stalled shortly after deployment. They have not given up trying to reach the design depth of 5 m down, but so far success getting deeper than 30 cm has totally eluded them.

My best guess is that there are some large boulders down there among all the sand, gravel, and ordinary rocks. Not at all surprising for a heavily-cratered planet. Nothing at all like the "standard" surrogate Mars regolith dirt. Cratered planet means lots of impacts. Which means in turn shattered rocks of all sizes. And I do mean all. I would have expected big buried boulders.

I also saw the hammered probe design was based entirely on that surrogate Mars dirt. Looks to me like the surrogate Mars dirt assumption was a really bad design choice. Sort of like Curiosity's aluminum tires, but worse.

GW

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