Yet another Mars architecture

GW Johnson · 2014-03-19 09:14:40

One of the tacit assumptions in all of these SLS and Orion projects is that only a capsule with service module and a propulsion stage is needed to fly beyond the moon. That's demonstrably not true. The key phrase is right in the pasted article: "The SLS program does not include the crew quarters. However, NASA is separately developing the Orion Crew and Service Module which will be integrated with the SLS at the launch site."

"does not include the crew quarters"!!!!! So, who's working on crew quarters for very long trips? In any significant way, I mean? Not NASA.

Flying beyond the moon requires months to years, not days. We have known since Gemini 7 in the 1960's that a crew in a cramped capsule is good only for a few weeks, maximum. Sufficient living space properly distributed among functions is required for long trips, period. And, you need to worry about solar flare radiation shielding, and for trips over about a year, microgravity disease. Otherwise, your crew comes home dead, nearly dead, or not at all.

I believe that the lack of effort toward long-duration flight is why "going to an asteroid" got subverted into "let the robot bring the asteroid to the moon, where we can go". Under such conditions, a private outfit has a better chance of sending men to Mars successfully in the next half-century than any of the government agencies. At least they have some motivation. The government quite clearly does not.

GW

Quaoar · 2014-03-19 10:12:48

GW Johnson wrote:

I believe that the lack of effort toward long-duration flight is why "going to an asteroid" got subverted into "let the robot bring the asteroid to the moon, where we can go". Under such conditions, a private outfit has a better chance of sending men to Mars successfully in the next half-century than any of the government agencies. At least they have some motivation. The government quite clearly does not.
GW

And even bring an asteroid in Moon orbit is not so easy for the robot, unless it has some kind of Jedi superpower: we need to develpoed an appropriate unmanned vehicle able to dock the asteroid, despin it, and move it with some kind of high efficient electric propulsion. All this hardware will not magically apper clapping the hands, but it need to be founded, projected, developed and tested.

GW Johnson · 2014-03-19 13:49:37

I think the "robot getting the asteroid" idea was limited to very small ones, around a meter or so in dimension. The problem, as I see it, is the de-spin operation. You can literally bag a thing that small, and drag it home. But it cannot be spinning when you bag it, or else it'll punch a hole in your bag.

The problem with de-spin is that you have to push on the thing somewhere, and more-or-less tangentially at that. Most of the data we have at the small asteroids visited so far by probes suggests that these things are dry, "fluffy", loose piles of all-different-sized rocks and mineral dust grains, bound together only by mutual gravity. That's very nearly no binding-together at all. They will exhibit very-near-zero bulk compression and bulk shear strength.

So, how do you push on a thing like that? In any direction at all? I'm not even sure that a stake driven into a thing like that will hold any force at all, in any direction, either: the particles will just "flow" around your stake. I'm guessing that you'll have to shine a laser on it, but not so much as to push the particles apart: you must use a weaker light pressure than the pull of gravity, and I don't yet know how to quantify that. But, I'd bet that it'll take a long time to have any effect.

GW

RobS · 2014-03-19 13:53:38

GW Johnson, I think asteroids as "fluffy" as you are describing can't be spinning very fast because they'd spin themselves apart. I think they are looking for a chunk of rock (up to 7 meters across, too) that they can engulf in a kevlar bag. Presumably that will spin the entire automated vehicle, but the vehicle can then despin itself and the asteroid in the bag. It does sound very tricky.

Quaoar · 2014-03-19 14:17:46

RobS wrote:

GW Johnson, I think asteroids as "fluffy" as you are describing can't be spinning very fast because they'd spin themselves apart. I think they are looking for a chunk of rock (up to 7 meters across, too) that they can engulf in a kevlar bag. Presumably that will spin the entire automated vehicle, but the vehicle can then despin itself and the asteroid in the bag. It does sound very tricky.

And they are spending billion for an heavy lift launcher only to get a 7 meter rock?

Tom Kalbfus · 2014-03-19 17:30:04

Its a 500 ton rock! Most spaceships are empty tin cans, rocks can be solid all the way through, that rock would weigh as much as five space shuttles, because space shuttles are hollow and that rock is likely not!

SpaceNut · 2014-03-19 18:25:03

Nasa plans Habitat Demonstration Unit – Deep Space Habitat Desert Research and Technology Studies http://www.nasa.gov/pdf/541196main_AnalogFactSheet.pdf

A follow up on this is that most of us look at the ISS modules in that they are basic building blocks that once made with simple modification are launchable to make up what we would need.

Last edited by SpaceNut (2014-03-20 18:41:53)

SpaceNut · 2014-03-20 19:06:04

Here is the most recent article http://spaceref.com/asteroids/nasas-ast … ssion.html

Tracking near-Earth asteroids has been a significant endeavor for NASA and the broader astronomical community, which has discovered 10,713 known near-Earth objects to date.
Asteroid Redirect Mission (ARM) represents an unprecedented technological feat, raising the bar for human exploration and discovery all while helping protect our home planet.
Paul Chodas, a senior scientist in the Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory, Pasadena, Calif. if size were the only factor, we'd be looking for an asteroid smaller than about 40 feet (12 meters) across with hundreds of millions of objects out there in this size range. Scientists estimate that several dozen asteroids in the 20-to-40-foot (6-to-12-meter) size range fly by Earth at a distance even closer than the moon every year.

More information about asteroids and near-Earth objects is available at:
http://neo.jpl.nasa.gov/
http://www.jpl.nasa.gov/asteroidwatch
http://www.twitter.com/asteroidwatch

GW Johnson · 2014-03-21 09:45:41

"500 ton rock" -- my point was that the best data we have says these are NOT rocks, they are rubble piles. The "space rock" concept is quite wrong.

Many of the smaller ones seem to have no binding ice: they are dry, and therefore quite loose. And, yes, they do reach a rotation speed where they fly apart. Lots of evidence for that already exists.

So, how do you push on a thing like that, for the robot asteroid diversion mission, or for a save-the-Earth deflection mission? Or for mining? That's what we have to learn how to do. With the variation from one body to the next in individual properties apparently enormous, how can investigating one be representative of them all? These are VERY serious questions with no firm answers yet.

We can always argue over whether it's smarter to defer (or not defer) developing the capability of long-distance manned travel in favor of a robot asteroid capture capability, so that we still only need the capability of reaching near-moon space with men.

Deferring that capability puts off sending men to Mars, but does allow you to recreate the capability of sending men to the moon, something we have so clearly lost. If instead, you have the capability of long-distance manned travel, then both asteroids in-situ and Mars become reachable with the same hardware (and the moon is "easy"). But, that's a tougher technological and proven-hardware "reach".

It's a ways-and-means thing. How best to go about answering those two fundamental questions about asteroids: (1) How do you push on one of these? (2) How variable are their properties, really? The answers are SO fundamental to so many things we might want to do. This is very important, we have to do this right.

You decide what's smarter for yourself. I did, I favor going straight after long-distance travel as enabling the bigger payoff.

GW

RobertDyck · 2014-03-21 11:59:36

*YOU* *DON'T* *PUSH* *ASTEROIDS* !!!

Mines on Earth do not move the mountain to a city, then mine at that city. You mine in place, smelt, then transport smelted product to a city. Gold mines smelt to 98% pure, then transport ingots to a refinery for further purification. Do the same with an asteroid.

Again I have to repeat, an asteroid aproaching Earth did not work out for the dinosaurs. Do you want to make all humans extinct?

If you want to know how to mine and smelt asteroid material insitu, read the website for an organization called Permanent. That's what they do.

Last edited by RobertDyck (2014-03-21 12:15:02)

GW Johnson · 2014-03-21 16:02:24

RobertDyck:

I was talking about the issues with NASA's asteroid retrieval mission, whether or not they ever really do it. What they had planned was not to visit with men a small NEO in-situ, they planned to use a robot ship with a can or bag, capture an itty bitty one, and drag it near the moon. Near the moon is a feasible mission duration for a crew to endure, crammed inside nothing but an Orion capsule.

If you're going to capture that itty bitty one, you'll have to de-spin it first, or it'll tear up the bag or can that you want to put it in. That requires pushing on it more-or-less tangent to the surface somewhere, to despin it. Either with a physical force or the force of a concentrated beam of light. That second option might (or might not) rely on thermal spalling to create a reaction force. Be that as it may, whatever force is used, it had better be weaker than the very weak gravity force binding the object together, or the thing will just fly apart in your face.

As for "killer" asteroid deflection, I first saw credible plans for this at the IAA conference on the subject in Granada, Spain in 2009. These plans revolve around either "little push" or "big push" methods. Little push is gravity tractors, small lasers, and similar. Big push is impactors and bombs.

There is no blast wave in space: nuclear bombs work from alongside as nothing more than super-intense flashes of light. That causes surface spalling, the reaction to which is your "push". Same thing would happen with a really powerful laser, just nowhere near as large an effect.

At that meeting, the concern back then was the unpredictability of reaction force to spallation. That's still unresolved, but since then, some more of the deflection community seem to have become aware of just how fragile some of these rubble piles are. I personally doubt that big push methods will ever work on an unconsolidated, non-ice bound, rubble pile. Disrupting one too close to home can turn a single billet hit into a shotgun blast, actually the worse outcome.

Underlying all of this worry is a complete lack of the subsurface "ground truth" of these things. What they are made of, how put together, any binding forces or agents, typical mechanical properties, that sort of stuff. As variable as they appear to be, I have grave doubts we could learn very much truly useful info by looking at just one.

That last is a really good argument for making the long voyage out there, and investigating as many as possible. What we learn for deflection also supports mining. That's a win-win. Plus we can look at all sizes, too. There's some reason to believe that size is the difference: why some have ice and others are dry. But, we just don't know, yet.

GW

RobertDyck · 2014-03-21 17:45:09

For mining, there are two types of asteroids you want. Metal asteroids are solid metal. They aren't rubble piles. Current scientific belief is a large asteroid formed with enough heat and size to melt the interior, and enough mass for gravity to differentiate material. Metals sunk to the core, while light materials like silicon and aluminum floated to the surface. This created a rock curst or mantle, with an iron/nickel core. Since this ancient asteroid required enough gravity for differentiation, they suspect it was large enough to be categorized as a dwarf planet. That is, large enough to be round. So about the size of Ceres. Then something happened to smash it into bits. Only 4% of near Earth objects are metal, but all of them had to come from one or more large asteroids / dwarf planets that broke up. Perhaps all are from a single body.

The other type of asteroids you want to mine is carbonaceous chondrite. That's because it has ice. It's basically part way between asteroid and comet. I proposed drilling like you would an oil well, but with an electric heating element on the drill bit. Once firmly within an icy deposit, heat the drill head. This will produce steam at first, but will quickly produce enough pressure for liquid water. The triple point is just 6.12 millibar, so 1% of an atmosphere pressure is 10 millibar, enough for water. Then warm muddy water will be pushed by this pressure up the drill pipe. Filter, process to form LOX/LH2.

So solid metal and consolidated with ice. Both relatively firm bodies. Just stay away from rubble piles.

A 1km diameter asteroid is far too large to move. Mine in place, transport the fuel or metal ingots. Mining will be via autonomous robotic equipment, but you probably will require visits by human crews to fix things. Yes, that requires going all the way out there.

I still argue for sending humans to Mars first.

RobS · 2014-03-21 20:57:19

I think NASA would want to avoid rubble piles for their capture mission. How would they do that? Spectral analysis will help; with it you can determine whether the body is nickel-iron, stony, chondrite, carbonaceous chondrite, a mix, etc. But they might still have a rubble pile problem. They can also determine how fast the objects are spinning and would want to find a slow spinning object. There are some out there. So farm they have not identified any potential targets. Maybe they never will be able to, or maybe the search is still in preliminary phases.

Otherwise, I agree with you: NASA really doesn't need to do this mission.

Quaoar · 2014-03-22 04:31:41

RobS wrote:

I think NASA would want to avoid rubble piles for their capture mission. How would they do that? Spectral analysis will help; with it you can determine whether the body is nickel-iron, stony, chondrite, carbonaceous chondrite, a mix, etc. But they might still have a rubble pile problem. They can also determine how fast the objects are spinning and would want to find a slow spinning object. There are some out there. So farm they have not identified any potential targets. Maybe they never will be able to, or maybe the search is still in preliminary phases.
Otherwise, I agree with you: NASA really doesn't need to do this mission.

If they really want to perform an asteroid capture mission, they have to start now in develping capture and retrial vehicle and hardware. But they are not seriously investing money in such mission plan.
Capture and retrial is a completly new technology and will take more than a decade to be operative. I also think it's better to go first on Mars: entry, descend, landing and ISRU are better known issues.

Last edited by Quaoar (2014-03-22 04:33:21)

RobS · 2014-03-22 05:35:18

I think part of their problem is they can't afford to develop the capture and retrieval system as long as they're developing SLS and Orion, each of which is costing something like 12 times as much as Falcon and Dragon combined!

Quaoar · 2014-03-22 09:02:41

RobS wrote:

I think part of their problem is they can't afford to develop the capture and retrieval system as long as they're developing SLS and Orion, each of which is costing something like 12 times as much as Falcon and Dragon combined!

The more logical think to do is to contract SpaceX to develop an heavy lift launcher for 1/4 of the money of SLS, or even less.

RobS · 2014-03-22 09:13:43

I think Musk said he could develop a super-heavy for $1 billion!

GW Johnson · 2014-03-22 09:15:08

Actually I agree with all of you. The disjoint here is looking at NASA's plans and proposals, and expecting something that makes common sense. NASA is is entirely managed by congressional politics. That's why nothing making any real sense has been done for 4 decades now. Expecting otherwise is insanity (by definition), until the politics is ousted from control over NASA's objectives. The other countries' agencies suffer from their versions of the same problem, so expect no better there.

As to our discussions about what to do with asteroids and whether-or not to go to Mars first, consider this. If you don't limit yourself to a minimalist mission design, the Mars mission quite naturally takes the form of an orbit-to-orbit manned transport, with some provision for landers. It gets built and launched from Earth orbit. This is a very old idea, at least 6 decades. But it's a good one, still. One good thing from the ISS experience is that we learned how to dock-together large structures from launchable modules. That's the key to the orbit-to-orbit transport construction. On-orbit refueling techniques still need development further, but that's at least being done with small quantities of storables now.

Now, here's the thing. Any such orbit-to-orbit manned transport must be capable of supporting its crew on long-duration flights: months to years in space. Any such vehicle is equally suitable for manned visits to Mars, the main asteroid belt, NEO's, Venus, and even Mercury! So why not build just one (or maybe two), build it tough and reusable, and over time do all of those things with it? As time and money permit, and opportunities suggest? Further, as "hotter propulsion" becomes available, refit it, and go further yet: moons of Jupiter and Saturn.

If you have a long-range plan like that, you can amortize the cost of building the ship over multiple missions. Then each mission just needs to pay further for developing the specific landers and surface equipment peculiar to that destination. Landers for Venus and the asteroids are unnecessary. Landers for Mercury will look more like those we used for the moon, just bigger. Landers for Mars will look like some sort of propelled space capsule, because of atmospheric entry needs.

But you have to have a long range plan, and the freedom to do things that make good common sense (instead of politics). No government agency on the planet has those things. And THAT'S why men haven't left LEO in 4 decades.

Final comment: this can be done with commercial launch rockets we already have (counting Falcon-Heavy, and that looks like a good bet). A super-heavy like SLS could reduce the cost somewhat, but only if were a commercially-driven low-cost system. NASA won't do that with a one-use design, they never have thought about how to launch cheaper in any significant way.

Atlas and Delta were commercialized, which drastically lowered their costs to the neighborhood of $2500/pound in 15-20 ton payload ranges. Simplified systems and logistics did this. Titan never was commercialized, and was about 4 times more expensive than what was finally achieved with the other two, compared at the same payloads.

If SLS were commercialized, it would be under $800/pound, following the curves evident from payloads and launch prices exhibited by commercial launchers from around the world. Nothing I have seen from NASA about SLS suggests they will ever be that cheap. Expect no savings there. You might as well fly smaller modules with the rockets we have. Same or lower price. And no waiting, they are flying now. Makes good common sense.

GW

Last edited by GW Johnson (2014-03-22 09:27:35)

RobS · 2014-03-22 10:42:34

I basically agree with you, GW Johnson, with the provision that we still know so little about the future, it is difficult to predict. We are rather in the same position as the development of the automobile was in the first decade before and after the year 1900. There were steam powered cars, electric powered cars, diesel and gasoline powered cars, and Henry Ford said the future belonged to alcohol powered cars. No one knew which propellant would come to dominate; no one could predict the power needed (electric cars were fine for 10 mph, weaving around horses for a few miles) or the cheap availability of petroleum. There are quite a few things we can't completely predict, but one of the most important ones is the cost of getting stuff to LEO. When you're talking about $2500 per pound ($5 million per tonne) fuel is very expensive, so nuclear and ion appear to be necessary alternatives. If Musk really does get launch costs down to $500 per pound ($1 million per tonne) then chemical propellant appears to be the cheapest alternative, even if you want to go fairly fast. A thousand tonnes of LOX/LH2, if it costs a billion dollars to get to orbit, is cheaper than developing a nuclear engine or a solar-ion tug or a system to move lunar water to LEO. But we really don't know whether $500 per pound can be achieved by, say, 2020 (let's give him a few years). IF that's possible, a reusable, durable vehicle (which will also be heavier and need more propellant) becomes more practical. When launches are very expensive, disposable, staged vehicles make more sense.

I suspect Musk will succeed. He literally can't make Falcons fast enough. He plans to double production in the next year. The first launch of a Falcon Heavy is postponed because they can't spare three cores to test it. They're developing a third spaceport (in addtion to Canaveral and Vandenberg) so they have enough facilities to keep up the launch rate. He said his prices were based on 10 Falcon and 10 Falcon Heavy launches per year; he is now at the point where he has to launch 13-15 Falcons per year to meet demand and he can't do it yet. He hopes to soft land a first stage some time this year. If he starts to reuse first stages--the biggest, heaviest part of the Falcon--then prices will indeed continue to drop. If a fully reusable Falcon Heavy can put 35 or so tonnes into LEO (not 53, because of the diversion of fuel to the soft landing) for $35 million, THAT'S a revolution. All sorts of things become possible. Any system to soft land stages on the Earth can soft land them, with modifications, on Mars or even the moon. I'm not sure we can adequately imagine the world of possibilities that opens up.

Beyond that, we will need a basic vehicle for journeys of several months or more. The design for that will evolve as well as we learn about the effectiveness of various levels of artificial gee (maybe 6 rpm and 0.3 gee is workable; we don't know), the various composities and plastics we can use, the possibility of magnetic shielding, the effectiveness and mass of long-duration life support systems, the mass of solar versus nuclear power sources, etc. Our initial "Model-T" interplanetary habs will improve. We will send people to the poles of Mercury, to Venus orbit, Ceres, Callisto, Titan. I think Mars is a perfectly good stage 1 for developing the vehicle(s) that will do this; we don't need a stage 1 with a near-Earth asteroid and make Mars stage 2. Personally, I think a return to the moon is an excellent stage as well and should be done, maybe before Mars, but that's a personal opinion (one I share with Paul Spudis, who I happened to go to grad school with, some 37 years ago!)

RobertDyck · 2014-03-22 11:00:50

GW Johnson wrote:

NASA is is entirely managed by congressional politics. That's why nothing making any real sense has been done for 4 decades now. Expecting otherwise is insanity (by definition), until the politics is ousted from control over NASA's objectives.

Worse would be control by bureaucrats. NASA was established explicitly for research into high risk / high pay-off technologies. Starting with NACA. One major problem with NASA is they have become increasingly controlled by their own contractors. They now think like corporate executives. They want low risk initiatives only, which defeats the point of NASA. For example, the project manager for Curiosity rover spoke at the last Mars Society convention. He said he refuses to consider ISPP for Mars 2020, or any future Mars mission. His excuse is it isn't "proven". And after failure of Mars Climate Orbiter, no attempt at aerocapture. They found the problem and solved it, but still no attempt to even try. Of course one issue is both these technologies exist to reduce cost, and contractors want to maximize cost. But another example: I have spoken to a few engineers for NASA and their contractors, about a "self-launching space station". This idea is to build a space station or major module into the upper stage of a two stage rocket. The upper stage would be filled with cryogenic propellant during launch, but equipment bolted to the inside of the tank. Once in space, the module would be vented of propellant, warmed, and filled with air. That would be the space station. Every engineer I've mentioned this to since the turn of the millennium has said this is a stupid idea. Would never work. Then I mention the name of the space station: Skylab. Yes, Skylab did fly in space. The Skylab workshop was the upper stage of a Saturn 1B, designed to be launched the way I just described. One aeronautical engineer pointed this out to me, and made a presentation at a Mars Society convention, but she doesn't work for NASA. NASA has lost this capability.

So, if you removed politicians, who would control NASA? Bureaucrats? Don't you think that would be orders of magnitude worse? Would NASA have anything left? Bureaucrats hate any risk what so ever, and are willing to spend any amount of taxpayer's money to avoid risk.

You could argue that Congress is way too large. The House of Representatives has so many individuals, all of whom have to be a star in his/her electoral district, that their demands for attention result in very little practical work. That's 433 drama queens. But the US system of government does have a way to cut through that: the President. You need a president who actually cares about space. Unfortunately Obama doesn't. During the 2008 election, his only comment was he wanted to send John McCain to Mars. I think he's a lot better than most Republicans, but to be partisan, I thought Ron Paul made the most sense. Libertarian is just sane. But his supporters morphed into the Tea Party movement. I disagree with much of what the Tea Party says. So now what?

RobS · 2014-03-22 11:17:29

So now what? Hope Elon Musk can do it! He says he wants to get people to Mars by the 2020s. And Lunar Ex wants to build a cheap series of small landers to put small payloads on the moon for about $175 million or less, including the Falcon 9 launcher (NOT Falcon Heavy). Lunar Ex says they can contract with NASA to, say, bring back 8kg of samples from a particular lunar landing site for $175 million, or put a small rover at the north or south pole to explore a cold trap for $175 million, or land a 500 kg space telescope at the south pole for $175 million. Go take a look at their website. When a capability like that exists, it will be hard for NASA to justify spending $500 million and 5 years to do the same thing; especially if Qatar or Brazil contracts for it. There's now a Silicon Valley startup that is launching 100 small satellites into LEO per year for a tiny fraction of the old costs, using cell phone electronics and standardized manufacturing. Pork barrel projects and bureacratic thinking are getting harder to justify.

Last edited by RobS (2014-03-22 11:18:36)

SpaceNut · 2014-03-22 15:09:42

Even with a fully developed system for mars travel there are just only so many customers that can afford it even a Musk's prices. So how do we make a mission to mars more affordable for the average working person. Even with subsidizing the mission with all of the movie rights and others stuff its the upfront costs that need to be reined in.

Quaoar · 2014-03-22 15:21:23

RobertDyck wrote:

The upper stage would be filled with cryogenic propellant during launch, but equipment bolted to the inside of the tank. Once in space, the module would be vented of propellant, warmed, and filled with air. ?

This is very interesting even for an ERV in a Mars Direct like mission: the LH2 tank for ISRU has a big volume that can be used for habitat douring the trip.
How can be avoided equipment damage by liquid hydrogen?

louis · 2014-03-22 15:43:46

RobS wrote:

So now what? Hope Elon Musk can do it! He says he wants to get people to Mars by the 2020s. And Lunar Ex wants to build a cheap series of small landers to put small payloads on the moon for about $175 million or less, including the Falcon 9 launcher (NOT Falcon Heavy). Lunar Ex says they can contract with NASA to, say, bring back 8kg of samples from a particular lunar landing site for $175 million, or put a small rover at the north or south pole to explore a cold trap for $175 million, or land a 500 kg space telescope at the south pole for $175 million. Go take a look at their website. When a capability like that exists, it will be hard for NASA to justify spending $500 million and 5 years to do the same thing; especially if Qatar or Brazil contracts for it. There's now a Silicon Valley startup that is launching 100 small satellites into LEO per year for a tiny fraction of the old costs, using cell phone electronics and standardized manufacturing. Pork barrel projects and bureacratic thinking are getting harder to justify.

You mean the MX-1?

http://www.moonexpress.com/

Interesting.

louis · 2014-03-22 15:50:59

SpaceNut wrote:

Even with a fully developed system for mars travel there are just only so many customers that can afford it even a Musk's prices. So how do we make a mission to mars more affordable for the average working person. Even with subsidizing the mission with all of the movie rights and others stuff its the upfront costs that need to be reined in.

I think it does come down to subsidy. In the past, on Earth, people moving to Australia were subsidised by governments. There's no great problem with the idea. It just means that for every, say, $250,000 it costs to transfer the person from Earth to Mars, you can cover that with surplus earnings and/or loans based on current earnings. I think costs could be further reduced by the Mars colony building its own lander/ascent craft for LMO to Mars surface.

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