Apolo LEM (LLM) possible on Mars?

From a thread awhile back someone proposed combining the landing module from the Apolo moon landing program, the space shuttle and a booster rocket to get people to Mars. the lunar landing mod. as was pointed out was not designed for the extra gravity of Mars, but it got me thinking, could it be retrofitted w/ a chute and maybe some extra fuel. (Now I know if you retrofit enough you could have the Concord land on Mars but I’m talking about very simple changes here.)

This is why I think is would work:
1 using the atmoshpere as a brake, you would use far less fuel for decent. - but getting down is the easy part
2 the lunar modual was loaded with rocks and luner soil, probally many times it’s own weight, if you took just enought martian soil to fill a ziplock baggie, you should have enought power to launch the craft.

Hopefully someone will have a conclusive answer (this is why I posted it here)

I’m no astrophysicist, but I play one on the T.V.

  1. The L.M. couldn’t use a braking chute very well, Mars’ athmosphere is radically different than our own. The gravitational pull, in relation to same while re-entering Earth’s athmosphere, is huge.

  2. For the same reason as stated in #1, you could land ( theoretically), and not bring along a speck of dust back to home, and still have a bitch of a time launching. Again…GRAVITY ! I’m sure in a little while, many fine scientific minds from our Teeming Millions will be along, but as basic knowledge, things that “weigh” X here on earth “weigh” several times X on Mars. Bigger body, more gravitational pull.

The L.M. would need to pack SUCH a force of fuel to escape Mars’ gravity, that it would weight SO much, that it would be hard to brake on the way in because of Mars’ gravitational pull, etc…see where this is going?
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I am not a rocket scientist, but I think there are two problems: The first is that Mars has an atmosphere. The Moon doesn’t. The LEM was not designed to work in an atmosphere. No heat shield, for one thing. Also, it’s not aerodynamic. The Apollo capsule could be steered a little because it was basically a very fat airfoil. It also had a lot less drag than the LEM would have. The second problem is gravity. Mars, while its gravity is less than Earth’s, has a greater gravity than the Moon.

Also, the LEM is 40-year-old technology. (Contrary to one UL, we didn’t “lose” the blueprints for the Saturn V rocket. We could build a new one, but where would we get 40-year-old transistors?) It would take as much engineering to make the LEM suitable for a Mars landing as it would to design something new specifically for a Mars landing. Maybe more engineering. (Where’s Anthracite when you need her?)

Interesting question. I think the major problem is going to be the heat generated by the aero-braking. You’re going to slam into the atmosphere at a speed comparable to the escape speed, which is about 5km/s. So the kinetic energy is about half that of a spacecraft in low earth orbit (7km/s). So I guess that means you need half as much shielding as a spacecraft designed to land on Earth…? Something like that, anyway. If your Mars program involves refueling a Space Shuttle and riding that to Mars, I think you’d be better off riding it all the way to the surface. Perhaps the entire LEM (the lander part as well as the ascent module) could fit in the cargo bay of the Shuttle, and used as a two-stage rocket to get off the surface. That should be more than powerful enough.

However, the biggest problem is that there is no way we can make a LEM now, because you can’t buy the components in the original design. Last year the launch of the Japanese Astro-E satellite failed, and the satellite was lost. They immediately decided to build an identical satellite, but one of the microprocessors was no longer in production and I believe they had to do some redesign to accomodate a new processor. They talked about it as if it could be a show-stopper. Imagine how much worse the problem is for a 30-year old spacecraft design.

I’d think it is MUCH more likely that a device will be perfected that will land, and have intuitive robotics on board. See This Discover Magazine Article from Jan 2001for details on the advances in Artificial Intelligence and intuitive robotics.

That way, one can peruse the soils, athmospheres, etc at will. Robotics will be hardy and able to work in the native environment. The analytical equipment is small, and can indeed be built into devices that are hardier than those that have malfunctioned so far upon landing ( or, shortly thereafter.).

I can see a Geodesic Dome-like structure being used to house both the analysis structure and the Hunt and Gather robotic vehicle. I don’t know why NASA didn’t use a similar shape to protect the Mars Landers that have failed- a Geodesic Dome is one of the few ( the only??) structures in the world that gain strength as size is increased, because structural stresses are shared over all panels evenly.

Hmmmmm. Time to dash off a quick note to Chris Craft. :wink:
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Geez, you guys type fast…

A rigid structure is no help in protecting instruments. You wouldn’t climb into a 4-ft diameter Geodesic cage and jump off the Empire State Building, would you? The major danger is shock (acceleration), not the collapse of the support structure. To reduce shock, you need either a braking mechanism (parachute, retro-rockets) or a shock absorption structure (e.g. the airbags used by one of the Mars probes), or preferably both. The problem with the Mars Polar Lander, as I understand it, was that the braking system was not tested properly, and most likely failed.

Okay, so I wasn’t so clear. Sorry… what I meant was, allowing for LOTS of padding WITHIN the dome, that type of structure would share the shock better than any other, and disperse shocks away and around from the materials within.

Hmmm. Shit. I’m on thin ice here. I don’t know how to prove that a Geodesic Dome would really share the shock better than a pyramid. I do know that the right padding materials would absorb shock significantly. ( i.e. high density charcoal foam, alternated with a thermopedic type of foam, and air padding bubbles).

However, I do agree that braking is kind of cruxial to the whole shebang. :smiley:

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I’m an engineer (albeit a chemical engineer, not a mechanical one, but still…), so I’ll add a few relevant observations. It would take at least as much work to retrofit a lunar module for a martian mission as it would to design and build a new module. So you might as well build a purpose-made Martian Lander. I’d make it an unmanned mission and use remote-controlled robots to gather the soil and stuff for analysis on the module. That way, you avoid the need for any form of life-support for astronauts, as well as the need to get them back to earth.

If you insist on a manned mission, then I’d say that you should assemble the module in earth’s orbit (Like at the International Space Station, if they ever get around to building the damn thing.) That avoids having to get the rocket off the ground first, allowing the module to carry more fuel for getting home.

Oh, and parachutes would work in the martian atmosphere. They’d just have to really big parachutes because the air is thinner there. I’d have booster rockets assisting them, as well.

This statement has me a little confused:

The surface gravity of Earth 980[sup]cm[/sup]/[sub]sec[/sub][sup]2[/sup], a little over 2 [sup]1[/sup]/[sub]2[/sub] times the surface gravity of Mars at 361[sup]cm[/sup]/[sub]sec[/sub][sup]2[/sup]. The LEM, being constructed in the gravity field of the earth would certainly be able to withstand the acceleration of sitting on the surface of Mars.

The Viking landers used a combination of parachutes to slow the craft to 60 [sup]m[/sup]/[sub]s[/sub] before the retros kicked in, braking the craft further and landing at a velocity of 2.4 [sup]m[/sup]/[sub]s[/sub]. I’ll leave it to someone who knows math better than I to figure out if it is feasible to simply scale this up for a LEM-like landing system, or whether the additional weight of the larger craft, crew and fuel for the ascent stage would make it impossible.

Aerospace engineer (mechanical) checking in…

Yes, you could probably rig something to protect the underbelly of the descent module and the landing struts from the Martian atmosphere (density approx 0.5 percent of Earth’s). You could re-stress everything for the greater Martian gravity, and train the crew to take the higher landing deceleration with their legs, as on the Apollo missions, even after an 8-months-long trip in zero G. You could rig a higher-thrust descent engine and ascent engine, as well as stronger thrusters, thicker skin material to counteract the atmospheric pressure, modern computers (literally, most cars today have more computing power than an Apollo spacecraft), the list is endless.

But at the end, you’d have a kludged-up conversion of a 40-year-old craft put together in a crash program to fit in the envelope defined by the diameter of a 40-year-old rocket, the entirety of which was meant for a very different mission to a very different place. It would cost a few billion dollars to do, even so, and might not save anything at all over designing a new spacecraft for a different mission using modern technologies throughout.

Over teaching about how oil does not contribute that much to World electricity production. :wink:

And staying quiet, knowing when there are people who can answer the question better than me. Humility is good.

I suppose lithobraking is out of the question if you wish to retrieve the instruments…

Lithobraking is sometimes (almost always unintentionally) used in aircraft, and the results have not been encouraging over the past 97 years.

Um…I stand ( sit ) corrected. Thank you so much- this is fascinating. I’m still in love with the idea of the Intuitive Robotics doing the work, but my concepts of physics are shut down now. :slight_smile: Right on…

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