New Mars Forums

Does anyone know the mass numbers for the refueling station lander that will create methane for crew return (MAV) from surface to the orbiting ERV?

Do we know if we are capable of landing such mass on the mars surface and its reliablity of success?

Is the mass simular to the LSAM?

Does anyone know what the maximum volume and mass of any mars landers that we would send to the surface can be?

Also how much of that same lander would be cargo or payload?

The Mav is a tiny capsule unfit for a six month journey to earth, it has no Earth entry heats shield as it would be heavy and not needed to be landed on mars, no parachutes for earth entry as the ones needed for mars entry have already been used. Then the stage to push the mav to Earth from mars orbit just made it not possible to land on mars. We do have size limitation of mass and diameters to work with.

Old argument. A few years ago Congress was beginning to realize no nuclear = no space.
.

No proven ice deposit anywhere we would send humans. Even GW Johnson says we can't rely on ice for the very first human mission. But you can rely on atmosphere. Using Zubrin's ISPP is far better than trying to bring return propellant from Earth.

There is ice at Vastitas Borealis Crater, but that's 70° north. Mars Direct has the crew stay 14 months on the surface (about 425 days), waiting for the planets to align for the return home. That's so much time that winter will fall. Mars gets very cold at night, but winter near the pole? Temperature will get so cold that you have to worry about material embrittlement. Much better to stay near the equator, where it's cold, but not that extreme. In other discussion threads we have discussed the spot on Elysium Planitia called "Frozen Sea" or "Pack Ice". It looks good, and radar from orbiters confirm layers, but have not confirmed ice. SHARAD on MRO confirms layers, but does not say what the layers are. Results from MARSIS on Mars Express do not have the dielectric expected for water ice. That could mean all the ice has evaporated/sublimated, or it could mean remaining ice is too shallow for that. They did confirm the dielectric for the south polar ice cap, but that is 3.7km thick! The "Frozen Sea" was 45 metres deep, but at least some has evaporated/sublimated. Is it all gone, or just too shallow for MARSIS? We'll have to drill to find out. Only 5° north of the equator (warm), low altitude (lots of atmosphere for radiation shielding), and flat/smooth (safe to land), so it's a really great spot; but you don't want to bet your life on ice just to find it's all gone..

Mars Direct was an attempt to send humans to Mars on an affordable budget. The price was $20 billion for the first mission, plus $2 billion per mission there after. Or if NASA commits to 7 missions up front, $30 billion. Buy 6 missions, get one free. (Yes it really does work out that way.) One mission every 26 months because that's when orbits around the Sun bring the planets into alignment. So $1 billion per year. That was in 1990 dollars, but still that's a lot better. In fact, since technology has advanced and we now have "New Space" companies, the price may end up the same. But when NASA was finally convinced to take Mars Direct seriously, they decided to re-invent it. They bulked it up from 4 crew to 6, and brought propellant for return all the way from Earth. It only uses ISPP for the Mars Assent Vehicle, to go from Mars surface to Mars orbit. That was the NASA Design Reference Mission (DRM). It was priced at $55 billion for 7 missions. Congress noticed the price jumped from $20 billion to $55 billion already, and they haven't even finished designing the thing. That convinced them NASA would end up demanding the full 90-Day Report, with it's gigantic price tag, so they said "No".

That is the reason Congress continues to refuse to allow any humans beyond Low Earth Orbit. They're afraid that any attempt to do so would result in the full price tag of the 90-Day Report. They are not ever, ever, EVER going to authorize that much money. Not anywhere near that much money.

Go cheap or go home.

If anything I would say the Jovian system is fairly amenable to this kind of inter"planetary" civilization, insofar as the bodies are fairly close to each other and don't have too high delta-Vs to get from one to the other.  There's also, ya know, four of them

If in the context of a story someone wanted to terraform the four moons you'd have a pretty good basis for a rocketpunk story.

Biggest problem with aerocapture/aerobraking schemes is the factor-2 variability of Mars atmospheric density profiles at high altitudes.  Your design has to allow for this,  so it is not as simple and lightweight as you might think at first.  They had to allow for that with the probes that have used it,  in the sense that the differences get partly made up at lower altitudes by lift during entry,  and the rest "lost" in the uncertainties of chute deceleration. 

Big items to be landed on Mars will not find chutes useful,  as they penetrate to too low an altitude for a chute to deploy,  much less do any deceleration good.  That leaves retro-thrust rocket braking as the only practical terminal landing method. 

I think for aerocapture,  you will have to accept a factor-2 variable outcome,  and carry the orbital maneuvering propellant to make up for it.  For aerobraking,  you will have to carry the extra propellant to make up the uncertainty in your retro-thrust rocket-braked terminal landing propellant. 

Either way,  you will be carrying extra propellants.  Propellants that could do direct braking or orbit modification anyway.  You won't save as much at Mars trying to use aerocapture/aerobraking as you would think at first glance.  It is the density variability at high altitude that causes this dilemma. 

Earth's atmosphere does not suffer this kind of variability at high altitudes,  which is why we had no prior experience with it at Mars.  It's why the landing ellipses were so very large on Mars,  until very recently. 

GW

Every module is small enough to launch with commercial rockets we have,  except the landers,  which have to be built-up in LEO from smaller components.  They're just too fat to ride a Falcon-Heavy,  although light enough. 

GW

Assuming nothing goes wrong,  the only piece that reenters is the small return capsule.  Having one with you enables an emergency free return if the engines both fail before arrival home.  But there are two engines. 

The propellant modules that come home arrive in LEO essentially empty.  To be reused,  they would need to be refueled on-orbit from some sort of tanker.

The habitat would need to be restocked with supplies from some sort of freighter.

Depending upon the nature of the engine design,  they might not need refurbishment before re-use.  At least,  that's the kind of design I would recommend.

Point is,  any ship capable of taking men to and from Mars orbit,  can take men to near-Earth asteroids (asteroid defense missions),  or to orbits about Venus and Mercury.

Or it can return to Mars orbit.  Why not build it just once to accomplish all those things as the time becomes right for each of them?  A different lander would be needed at Mercury,

but Venus and the asteroids need no landers at all.  You will need more propellant modules,  but so what?

GW

If instead you want to use LOX-LH2,  your site has to have lots of easy water,  or your ISPP cannot work.  But solar-powered electrolysis will generate hydrogen and oxygen faster,  I think,  as long as you can liquify them.  Rapid liquifaction is the "long pole" in that tent.  In part,  because you must store immense volumes of uncompressed gases before running them through the liquifaction plants.  "Plants" plural because the equipment to liquify hydrogen gas is quite different from the equipment to liquify oxygen. 

GW