Alternative Mars Architecture based on Constellation

cIclops · 2007-11-21 01:36:37

Ripped from Utilizing Lunar Architecture Transportation Elements for Mars Exploration (PDF) - October 2007

A simpler solution than DRM 5.0 using Ares V and Ares I with no NTR or ISRU.

o 2030-2040 timescale
o Crew size of three
o Conjunction class 500 surface day mission
o 4 x Ares V and one Ares I launcher
o Inspace propulsion stage
o Aerobraking/aerocapture at Mars
o RTGs for rover and Hab
o Fully closed life support system
o Inflatable MTV (MEV) & Hab
o Zero boil off cryogenic fuel storage

o LOC 12%
o LOM 39%
o Cost estimate: $24 billion per mission

JoshNH4H · 2008-02-02 13:35:41

Looks good except for a few small issues
1. 12% loss of crew?! half it, then I'll be happy.
2. 39% MOC What's MOC, b/c if it's bad, that's way too high.
3. No boiloff of the hydrogen?! not possible
4. COMPLETELY closed LSS? Very hard w/ current tech.

cIclops · 2008-02-03 01:34:57

Yes 12% is too high, that's means losing a crew every 8 missions. LOM (Loss of mission) is always higher, but again 1 mission failing every 3 will make it hard to sustain the program. Zero LH2 boil off, or very close to, is possible but unproven in space and it adds mass of course. This proposal is targeted around 2030-40, it's reasonable to assume that fully closed life support technology (air, water, food) will be available by then.

BTW the ESAS study found that lunar landing missions will have a LOC of 1.6% and LOM of 5.9% The Shuttle has a flight history LOC of almost the same.

JoshNH4H · 2008-02-03 09:56:20

Just wondering, what were the stats (estimated and real) of apollo?

Terraformer · 2008-02-03 10:00:28

Moon landings or not? Of the Moon landings there was Zero LOC and One LOM. I think some off the crew were lost in the missions before though.

JoshNH4H · 2008-02-03 10:06:15

everyone died on apollo I. I mostly meant pre/post mission estimates, because there were only 16/17? apollos.

SpaceNut · 2008-02-04 09:05:35

The problem is that the numbers for what actually happens need to be way lower than the calculated.

RedStreak · 2008-02-04 15:12:24

It's not a bad study, but it could use some tweaking as you guys already suggest looking at the numbers.

One flaw I see is the In-Space-Propulsion-Stage. Why the 'drop tanks'? Wouldn't the plumbing/insulation requirements alone for 6 LOX tanks cause more boil-off issues than one large tank? Next mistake is use of 3 or 4 engines - wouldn't that add more mass to carry versus one J2-X engine? My personal suggestion would be making a stage based on the current EDS - a further suggestion would be to modify it for LOX/CH4 propulsion to take advantage of less boil-off CH4 has than H2; it's unrealistic to think H2 can be contained completely for 2 to 4 years but it'd be at least more feasible with methane. If you can hold LOX that long then you could do same for CH4.

The In-Space-TransHabs are a great idea on other hand. I'd recommend concentrating more of the mass to the lander itself, but giving more room for living space not a bad idea. Venting the CH4 from the sabatier reactor sounds like a waste, especially if H2 is going to be a commodity. Why not pump the CH4 into the thrusters? Save a little mass using tech that might prototype the technique on Mars later.

The Habitat modules look decent enough to use. Their MEV could use more tweaking, mainly in ISRU.

Altogether this plan seems little different from the ol' Mars Semi-Direct, except in specifying (and renaming) components; the use of TransHabs is the only 'big deal' I see coming out of this. They're obviously trying to be direct and realistic in eliminating ISRU development costs...but considering the time table of 2030...wouldn't we have both tested a working CH4 engine and ISRU on Mars by then?

My opinion on this plan - drop the ISPS for an 'EDS2' (maybe rename it the Mars Departure Stage), keep the TransHabs, and don't underestimate ISPP.

RedStreak · 2008-02-04 15:25:02

Part of the literature of this plan, I noted, is doing a series of sortie missions. They seem worried that concentrating resources to a single Martian base would limit exploration. Interesting point there; whereas the Moon will be more prospect and application Mars would be a genuine object of exploration.

I'd suggest establishing two sites for two different purposes:
1) Resource Utilization
2) Maximum science

We could choose two sites, one focusing on extracting resources and the other purely science. I suggest this on the grounds that Mars will likely be thin on sites that harbor both of these - the Tharsis Volcanoes and Valles Marineris are in the same 'region' of the planet, but neither is a huge ice reservoir for instance. Likewise the Martian poles or Merridiani have water-rich-materials but, save polar cores, no specific scientific sites.

Two small bases could be established, with the occassional 'sortie' sent out to the perimeter ranges of both bases. Most cargo launches ought to be directed to the resource base to build-up an eventual permenant habitat but human crew would otherwise be split between the two. Hopper Landers or Martian vehicles could likely keep the two bases in touch as well.

GCNRevenger · 2008-02-04 15:30:49

Maintaining two separate bases could wind up being pretty expensive though. Instead, lets have a single "main" base that supports (fuels) rocket powered "hoppers" that go exploring planet-wide. These could land and stay at a particular spot of interest for a little while perhaps. Surely the science won't be neatly concentrated any one place on the planet.

aftercolumbia · 2008-02-04 17:52:40

I don't see how it can work without ISRU. Zero LH2 boiloff in space is much easier than it is on the surface of Mars (which would probably require so much power for ascent performance hydrogen tanks that you might as well use ISRU anyway.) Consider an easily achievable 450sec no ISRU oxyhydrogen system with a equally easily acheivable 92% ISRU oxymethane system with an Isp of 350sec. Assuming you land a 60 tonne booster in each case and need to execute a 5000m/s ascent to an ERV in an elliptical orbit (why elliptical? Zero boiloff is easier to achieve in an elliptical orbit and saves the ERV's propellant supply either from use for lowering the orbit, or from boiling off due to aerobraking heat.)

With the oxyhydrogen no ISRU zero-boiloff version, you reach orbit with a mass no higher than 19.33 tonnes (this includes the stage and payload for a single stage ascent; it is theoretically impossible to get more payload than this with staging.)

With the oxymethane 92% system, there needs to be an assumption about how much seed material (typically liquid hydrogen) you will have on board. Let us assume that it is 20 tonnes, leaving 20 tonnes of booster (not much more than the 19.33 maximum above) and 20 tonnes of ISRU plant. These numbers are quite reasonable. The 92% ISRU leads to a mass multiplier of 12.5, so your 20 tonnes of seed hydrogen will be a part of 250 tonnes of complete oxymethane propellants. With the given Isp, 250 tonnes of propellant can lift off with a mass of 326 tonnes, leaving 76 tonnes to share between the 20 tonne empty booster and its payload. This translates into a 56 tonne payload, not including the stage structure!!

The directly comparable numbers are 19.33 tonnes orbital mass for the non-ISRU booster vs. 76.06 tonnes for an ISRU booster that is pretty conservative. That's 56.72 tonnes more you can come home with (barring the inevitable complications from the ERV, which would probably bring that number down to around 40 tonnes.)

I would guess that ISRU will be far easier (cheaper) to design, build, test and qualify for flight than the 60 tonne lander!! (ACMD (another thread) uses a 6 tonne lander for this reason.)

"60 tonne lander" means a lander designed to land a useful payload of 60 tonnes, same with "6 tonne lander"; the complete lander at entry is expected to amass about twice as much.

RedStreak · 2008-02-04 17:53:27

Maintaining two separate bases could wind up being pretty expensive though. Instead, lets have a single "main" base that supports (fuels) rocket powered "hoppers" that go exploring planet-wide. These could land and stay at a particular spot of interest for a little while perhaps. Surely the science won't be neatly concentrated any one place on the planet.

That'd be a preferable alternative, first choice even. This article/architecture though seems to argue against that and more of a series of sorties...which in the long-term doesn't do much. :? I think they were gearing toward keeping the public and science community 'entertained' so to speak...which if done rigorously could work but would end up requiring as much capitol as maintaining two bases I bet.

RedStreak · 2008-02-04 18:02:43

I don't see how it can work without ISRU. Zero LH2 boiloff in space is much easier than it is on the surface of Mars (which would probably require so much power for ascent performance hydrogen tanks that you might as well use ISRU anyway.) Consider an easily achievable 450sec no ISRU oxyhydrogen system with a equally easily acheivable 92% ISRU oxymethane system with an Isp of 350sec.

Agreed. I don't think any mission, even in 2030, could travel more than 30 days from it origin point (Mars, Earth, or Moon) without 10% plus H2 boil-off.

With the oxymethane 92% system, there needs to be an assumption about how much seed material (typically liquid hydrogen) you will have on board. Let us assume that it is 20 tonnes, leaving 20 tonnes of booster (not much more than the 19.33 maximum above) and 20 tonnes of ISRU plant. These numbers are quite reasonable...
...This translates into a 56 tonne payload, not including the stage structure!!

I would guess that ISRU will be far easier (cheaper) to design, build, test and qualify for flight than the 60 tonne lander!! (ACMD (another thread) uses a 6 tonne lander for this reason.)

I definetely agree with all that, and it all can be summed up as never underestimate ISRU!!

GCNRevenger · 2008-02-04 22:22:31

Don't be so quick to discount the tank insulation people or the possibility of a compact, light weight boil-off condenser for hydrogen... the Apollo SM cryogenic tanks of fifty years ago could hold ice at 70F ambient for several years as the legend goes. And the Martian atmosphere may insulate better than you think too.

RobertDyck · 2008-02-05 10:37:51

Meridiani Planum is the ideal site for both science and resources.

The hematite concretions, known as "blueberries", were formed by water. However, they are also a hard iron oxide mineral contained within soft rock. That makes them easy to separate from the matrix, just crush with something strong enough to crush jarosite or other matrix rock, but not strong enough to crush hematite. Then tumble the concretions to shake any further material from them, and sift. The concretions are such pure iron ore that the direct iron method of smelting will work, which only requires 900°C. That's cool enough to be produced directly from a nuclear reactor. Meridiani Planum also has substantial water underground, more so than any other large equatorial region. Water is a major resource for resource extraction. For one thing, you need hydrogen and carbon monoxide as the working gasses to smelt iron. Hydrogen is needed to turn carbon dioxide into carbon monoxide. There's also clay and gypsum at Meridiani Planum. Clay is used to make brick; gypsum is used to make wall board or plaster.

As for science, the scientists want to find life. Meridiani Planum is the most promising location for the search for life. Dr. Carol Stoker thinks the high sulphur content there is caused by a geyser. That geyser could also provide heat and water to harbour extant life today.

The only problem with Meridiani Planum is its high altitude. Ideally you want a base location below the datum to provide maximum atmosphere for radiation protection. But you also need a location in tropical latitudes for warmth, plenty of ground water, plenty of resources, scientifically interesting, and safe to land. Any other location would be the bottom of a valley, hard to land in.

I nominate Meridiani Planum for Mars Base One.

RedStreak · 2008-02-05 11:00:27

I nominate Meridiani Planum for Mars Base One.

I'd second that. On a Martian globe what are the nearest geologic features a long-range rover might come across? I know the Tharsis Volcanoes, Olympus, and Valles Marineris are almost half a hemisphere away but there should be something nearby...

RobertDyck · 2008-02-05 16:17:16

Mars is a big planet. Even with a range of 2,000km, a rover would only be able to go 1,000km and back. If travelling at 30km/h (about 18.6 mph), which is about right for rough off-road terrain, that would take 2 days 18 hours 40 minutes round trip. A long range. A radius of 1,000km from a base at Meridiani Planum would not leave the larger region of Terra Meridian. I would like to give an interesting list of objects, but for some reason the Mars clickable maps don't load on my computer now, and I have an appointment with a friend for the evening. Gotta go.

cIclops · 2008-02-05 17:14:02

The way exploration of Mars happens will be determined by the technology and science available at the time. A mobile platform with nuclear power has a lot of advantages over a fixed base. Combined with aerial vehicles and smaller pressurized rovers for remote sorties, such a platform might be the best solution. Sooner or later a static base will be established at a site that will probably be chosen more for local resources than fleeting scientific interest. Water will be the key resource initially. Other resources such as ores won't be a factor for a long time, manufacturing anything other than air and fuel on Mars will be far too expensive.

GCNRevenger · 2008-02-05 19:40:04

I am solidly against any "mobile base" concept, its just not a good idea:

-The base will require nuclear power, and a mobile reactor will need to be much more powerful (and heavy, and expensive) then for a stationary base. Don't forget the shielding either, and Mars dirt is pretty heavy per amount of shielding too I'll bet, or irradiating your water by using it as shielding isn't a good option either.
-Mobility adds mass and restricts volume, which is going to need some serious wheels/shocks/motors etc and will probably make arranging a spacious enough HAB difficult if not intractable.
-Many Mars plans call for the HAB to be separate from the ride home, and traveling around long distances from the ride home is a bad idea. We will, as a matter of necessary competence, be able to land with accuracy.
-Having a mobile HAB runs counter to the goal of building up a base as cheaply as practical (most mass per dollar).

Later on, after we have the base with a supply of water and some decent ISRU capacity, then we have rocket-powered "hoppers" for long range trips.

Before then, we should stick with long-range rovers and the occasional sortie directly from Earth. A possible stop-gap might be prepositioning "gas stations" (solar/dRTG ISRU?) or supply depots to extend the range of the rover.

GCNRevenger · 2008-02-05 19:43:18

Water will be the key resource initially. Other resources such as ores won't be a factor for a long time, manufacturing anything other than air and fuel on Mars will be far too expensive.

A very long time. The positioning of building materials should not enter the calculus for landing/base sites whatsoever. If anything, polymers (which will make up most everything that doesn't need to be built on Earth) can be made from water and Martian CO2 if you aren't in a rush to make mass quantities.

cIclops · 2008-02-06 02:35:36

I am solidly against any "mobile base" concept, its just not a good idea:
-The base will require nuclear power, and a mobile reactor will need to be much more powerful (and heavy, and expensive) then for a stationary base. Don't forget the shielding either, and Mars dirt is pretty heavy per amount of shielding too I'll bet, or irradiating your water by using it as shielding isn't a good option either.
-Mobility adds mass and restricts volume, which is going to need some serious wheels/shocks/motors etc and will probably make arranging a spacious enough HAB difficult if not intractable.
-Many Mars plans call for the HAB to be separate from the ride home, and traveling around long distances from the ride home is a bad idea. We will, as a matter of necessary competence, be able to land with accuracy.
-Having a mobile HAB runs counter to the goal of building up a base as cheaply as practical (most mass per dollar).
Later on, after we have the base with a supply of water and some decent ISRU capacity, then we have rocket-powered "hoppers" for long range trips.
Before then, we should stick with long-range rovers and the occasional sortie directly from Earth. A possible stop-gap might be prepositioning "gas stations" (solar/dRTG ISRU?) or supply depots to extend the range of the rover.

All good points. However, a mobile Hab (calling it a base is too grandiose as its mass will be very restricted, and it will prob only accommodate six) has many advantages. Not least is the ability to optimize its location. Precision landing on Mars may not be possible for some time and error ellipses may be kilometers (MSL will be 20 kms circular). Otherwise, the base/hab is stuck wherever it lands. Once it has mobility, then why not full mobility? Likewise the reactor can also be mobile on a separate platform, landed separately and hooked up with a long cable or perhaps beam power directly from a safe distance. This configuration gives maximum flexibility and minimal risk.

Given a mobile base, pressurized rovers can be smaller as they won't have to cover increasingly longer distances as new sites are located by satellite and aerial platforms. Aerial vehicles capable of transporting crew, shelter, equipment and supplies for remote exploration will be heavy too, and unlikely to be available for some time. Initially all exploration will be on foot or by rover.

A primary traverse for the base would be planned, and the area either side would be explored by the rovers. As expeditions would have 500 days, such a base could move in say 100km steps every 100 days. The base ends up back at the return vehicle, that would have been refueled by ISRU powered by the mobile reactor before the base arrived.

Reuse of these mobile elements may be possible between expeditions. Deciding the location for a fixed base may take several expeditions, their mobile elements can move to this location when its identified. Mars is a BIG place, deciding on one spot for a permanent base will take time. If expedition elements are not mobile, those elements will surely be wasted.

RedStreak · 2008-02-06 02:45:49

Personally I'd just stick with a solid habitat near one major site and use a large rover to investigate more distant targets. Anything more than a few thousand kilometers away you might as well send a new habitat/lander for.

RobertDyck · 2008-02-06 20:27:52

The bounce and roll landing of Mars Pathfinder/Spirit/Opportunity is not possible for humans. They used an aeroshell for initial atmospheric entry, a drogue chute, then a parachute, rockets on the parachute cords for the last seconds before impact, and air bags for the ground impact. Works for sturdy equipment, but the initial impact produces 25 Gs of acceleration. That will make any astronauts chunky salsa on the back wall. Even padded acceleration couches with seat belts will not protect astronauts from that acceleration. To survive you need landing rockets with legs and shock absorbers in each leg. Viking landers used that, and Phoenix will as well.

The proposal for the Canadian Mars lander included a lidar system to map terrain beneath the lander, and software to look for level terrain free of large rocks. Lidar works similar to radar, but it scans a laser beam. The lidar systems are already sold by Optech, they have a display at all Canadian space functions. The Apollo LEM was able to thrust sideways for a bit before landing, a Mars lander will certainly do as well. I think precision landing will be available for the first Mars landing; this is the 21st century.

GCNRevenger · 2008-02-06 21:53:31

Having a nuclear reactor poke along behind you on a separate truck? I don't like it, the reactor still has to be extra-big to generate enough power, and the cable will be very troublesome if not dangerous. You are also eliminating a large swath of terrain you won't be able to move around in: the area behind you, as there will be too much radiation.

Also making the HAB mobile really does place unacceptable constraints on the volume of the HAB, especially with add-on modules down the road or whatnot.

A permanent base should also be higher on the priority list I think, especially to get at the one resource that is critical for the future: water. We will want to establish a drilling rig for water as soon as we reasonably can, which calls for a stationary location.

And being that Mars is such a big place, the short range of a mobile HAB won't cover much more of it than rovers could thanks to its lower speed. For that matter, nor would it be a good option for finding a permanent base site.

Commodore · 2008-02-06 22:54:34

I feel compelled to point out that the goal of the first few launch windows, even the first decade, is not to poke at every mildly amusing rock within a 500km radius, but to assemble, fabricate, an build up a capability to support a growing human population, which can then in turn poke at rocks at will.

Towards this end, we will want to establish a handful of continuously occupied, fair sized bases on opposite sides of the planet built of both local and imported equipment, capable of producing a surplus of life support goods, like food, water, air and fuel. Smaller outposts evenly spaced in between to store supplies, and other wish serve as semi-permenent outpost for more localized exploration.

Within a decade, the entire planet will be open to the kind of purely scientific rock poking everyone seems so excited about.

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Re: Alternative Mars Architecture based on Constellation

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