Initial Mars base with ITS

[punder]

Been playing around with an idea. My usual disclaimer--if it's been hashed out already, mods please move to existing thread or whatever is appropriate.

The idea is to land two uncrewed ITS in the first synod. Neither is intended to fly again. One is a "wet" habitat, in which the prop tanks will be converted to living space. The other is the fuel production and storage facility, in which the "payload" is the machinery that condenses and converts atmospheric CO2 into LOX and CH4, with the prop tanks serving as the storage tanks.

Both landers include a rotating crane at the top, with the arms collapsed inside the nose, or stored inside fairings along the side, during launch. Note that tall cranes usually need a massive translating counterweight on one end. That's  coming.

One or both landers carry a number of very lightweight robotic earth-moving vehicles (EMs). But of course earth-movers must be massive--that's coming too.

Once landed, the crane deploys. The two opposite arms are positioned over opposing opened hatches, extract equally massive EMs, and lower them to the ground. This process continues for the radially stored pairs of vehicles or other equipment until all have been set down.

The lightweight EMs are converted to effective heavyweights by taking on mass in the form of Martian soil or stone. This might be accomplished using a single bulldozer to slowly (using small loads that don't violate its CG) dump material into "sidecar" compartments on a second bulldozer. Once the second dozer is fully weighted, it can very quickly load the first dozer and the other EMs.

Next, the counterweight end of the crane extracts a lightweight bucket or sack and lowers it. The dozers fill the container with soil, which is hoisted into place under its translating cradle. One of the other EMs may be used as an opposing mass for this operation if needed.

Now, the real point of the cranes: Another part of the payload is a batch of large, segmented sacks (made of an appropriate Mars-durable material of course). A sack is lowered to ground and filled with soil by the EMs. It is then hoisted to a particular spot along the ITS hull and secured there, using rope lanyards hung from an array of carabiners mounted in a ring near the top of the lander, or at convenient points on the hull. This process continues until each ITS is uniformly covered with bags of soil.

This layer of soil bags does triple duty: it provides radiation protection (especially for the hab), insulation, and protection from impacts (in the form of both meteorites and rocks thrown up by future landing ITS).

The prop lander spends the next two years converting atmosphere into fuel, oxidizer, and air for the crew that arrive next synod. The EMs are primarily engaged in locating and extracting subsurface ice for water (edit, and the "H" for the CH4), but also in building infrastructure, such as propellant pipelines to a suitably distant ITS spaceport and protective garages for surface equipment. Perhaps a borer goes to work, as well.

EM power might be solar-electric, but an alternative is IC using LOX/CH4 from the prop lander. At first, this would be leftover reserves from the landing.

The hab prop-tank living space might be built up robotically, or perhaps by the arriving crew, or a combination of both. Perhaps this lander's tanks were built with skeletal floors and walls pre-installed.

That's all I have at the moment. Might do some Solidworks later.

Okay, what do you think?   

[Oersted]

Interesting idea. I think you should read through the "Envisioning amazing habitats" thread, lots of ideas in there too, both futuristic and realistic.

[punder]

Interesting idea. I think you should read through the "Envisioning amazing habitats" thread, lots of ideas in there too, both futuristic and realistic.

I've read the first few pages, and it seems to concentrate mainly on longer-term issues. But I'll keep reading...

[Paul451]

Been playing around with an idea.

Firstly, it seems to me that you're proposing a lot of systems (and hence a lot of development cost) that don't play a role in later versions. The extra-size crane, the sandbag shielding, the "wet" tank/habitat, etc. If it isn't part of the long-term colonisation model, it won't fly.

Secondly, the early flights will almost certainly have a limited number of crew and no passengers/colonists. Any vehicle capable of supporting 100 people for the flight to Mars will be capable of supporting, say, 20 people on Mars, even flying with extra shielding (if necessary.)

Thirdly, the first humans to Mars will return to Earth. Any earlier non-return flights will be cargo only.

Lastly, micrometeorites burn up in the Martian atmosphere. Small meteorites large enough to reach the ground will reach their own terminal velocity before impact, well within the capability of the existing shielding of any man-rated space-vehicle. And no regolith shielding capable of stopping a meteorite large enough to reach the ground with significant impact energy will be able to be supported by a tall-thin "building".

[spacenut]

Earth moving equipment does not have to be as massive on Mars.  Remember Mars has only about 40% gravity of earth.  Earth moving equipment could be made from titanium or aluminum.  Tracked equipment on earth is made that way for mud and snow traction.  Also, front end type loaders have counter weight for lifting heavy soil and rocks.  Usually the equipment's weight offsets that.  Mars is dry, so tracked equipment may not be necessary.  Metal wheels may be all that is needed.  They can be made from spring steel and titanium.  Frame could be made from aircraft aluminum.  Front scraper/lifter could be made from titanium.  Yes, it will all be "heavy" equipment, but not really steel weight wise.  Even if you did make stuff from steel, it would only have to weigh 40% as much as one for planet earth.  A 10 ton earth front end loader, would only have to weigh 4 tons for use on Mars. 

[sevenperforce]

Earth moving equipment does not have to be as massive on Mars.  Remember Mars has only about 40% gravity of earth.  Earth moving equipment could be made from titanium or aluminum.  Tracked equipment on earth is made that way for mud and snow traction.  Also, front end type loaders have counter weight for lifting heavy soil and rocks.  Usually the equipment's weight offsets that.  Mars is dry, so tracked equipment may not be necessary.  Metal wheels may be all that is needed.  They can be made from spring steel and titanium.  Frame could be made from aircraft aluminum.  Front scraper/lifter could be made from titanium.  Yes, it will all be "heavy" equipment, but not really steel weight wise.  Even if you did make stuff from steel, it would only have to weigh 40% as much as one for planet earth.  A 10 ton earth front end loader, would only have to weigh 4 tons for use on Mars.

Uh........

A 10 ton earth front end loader DOES only weigh 4 tons on Mars.

[spacenut]

Yes, but you don't need one even 4 tons on Mars.  I've worked around heavy equipment, and it is designed for earths gravity and weight of the earth being moved.  It doesn't need to be that strong or heavy on Mars.  Thus titanium or aluminum equipment.  The equipment taken to Mars would only have to weigh 4 tons on earth, to match Mars conditions.  Replacing a 10 ton earth piece of equipment.  So the equipment could be much lighter. 

[Paul451]

It's worth remembering that a 10 tonne (or 4 tonne or 1 tonne) vehicle on Mars has the same inertia, but much less traction due to reduced down-weight. That requires a design similar to working on low-friction surfaces on Earth, such as very wide tracks. However Mars, being rocky, will have the wear issues of dusty/rocky environments on Earth (which mud/snow tracks aren't intended for), that excludes some of the "cheats" used on low-traction vehicles (such as spikes/nubs or ridged/bladed tracks).

They will need to be a uniquely Martian design, or else will be over-engineered (hence heavy) in some areas and under-engineered (hence high-maintenance) in others.

[MickQ]

I like the basic idea but I would lean more toward one ITS as the prop plant as planned and the other to carry two
earthmovers and a number of inflatable habs and an airlock module.  The earthmovers dig trenches, habs and airlock module are put in the trenches and connected together then regolith pushed on top.  The airlock module has a number of separate locks for redundancy and also acts as a hub to connect all the hab units together.

I would leave the ITS intact as another prop storage area and also as an escape vehicle if needed in the near term.
It could also supply power for the habs until a more permanent power station is set up.

[sghill]

We've covered all of this in exacting detail in numerous other threads.

[redliox]

How much cargo could an ITS with a small crew (10 or less presumably) land on Mars?  The numbers I see on the ITS specs cite 450 mt to Mars post-fuel transfer in LEO, with 300 mt for 'cargo' but really translating to fuel for Mars Injection and EDL and crew supplies.  Trying to see what the breakdown would be...

To hit the 3.6 km/s from LEO the ITS needs to burn 280 mt of methalox with an ISP of 382 from the vacuum Raptor engines.  Out of that full 450 mt that leaves 170 mt, of which 150 is ship structure and presumably at least 10 mt of reserve methalox to give about 225 m/s of ELD.  10 mt of cargo sound right?

[envy887]

How much cargo could an ITS with a small crew (10 or less presumably) land on Mars?  The numbers I see on the ITS specs cite 450 mt to Mars post-fuel transfer in LEO, with 300 mt for 'cargo' but really translating to fuel for Mars Injection and EDL and crew supplies.  Trying to see what the breakdown would be...

To hit the 3.6 km/s from LEO the ITS needs to burn 280 mt of methalox with an ISP of 382 from the vacuum Raptor engines.  Out of that full 450 mt that leaves 170 mt, of which 150 is ship structure and presumably at least 10 mt of reserve methalox to give about 225 m/s of ELD.  10 mt of cargo sound right?

No, 10 t is off by over two orders of magnitude.

Total mass in LEO after refueling and on-orbit cargo transfer would be 2550 t. Mass after TMI would be ~900 t. Total landed mass on Mars surface is 600 t, composed of 150 t ship + 450 t payload.

[rsdavis9]

How much cargo could an ITS with a small crew (10 or less presumably) land on Mars?  The numbers I see on the ITS specs cite 450 mt to Mars post-fuel transfer in LEO, with 300 mt for 'cargo' but really translating to fuel for Mars Injection and EDL and crew supplies.  Trying to see what the breakdown would be...

To hit the 3.6 km/s from LEO the ITS needs to burn 280 mt of methalox with an ISP of 382 from the vacuum Raptor engines.  Out of that full 450 mt that leaves 170 mt, of which 150 is ship structure and presumably at least 10 mt of reserve methalox to give about 225 m/s of ELD.  10 mt of cargo sound right?

No, 10 t is off by over two orders of magnitude.

Total mass in LEO after refueling and on-orbit cargo transfer would be 2550 t. Mass after TMI would be ~900 t. Total landed mass on Mars surface is 600 t, composed of 150 t ship + 450 t payload.

l(450/10)/l(10)=1.65
So about a magnitude and a half off

EDIT: fixed total vs payload