Mars 24 Project - To Mars with Existing Commercial Rockets

RobS · 2002-09-29 23:07:51

OVERVIEW OF PHASE 3 (YEARS 11 AND 13, MISSIONS 5 AND 6; OR LATER)

The base now has 5 habs and 5 greenhouses, able to accommodate up to 15 people and feed about 10. Electrical capacity on Mars is now about 300 kilowatts. Transportation capacity between the planets is now 8 people in either direction. Phobos now provides almost enough fuel to supply all the needs of Mars missions, including pushing the automated cargo vehicles to Mars on a Hohmann trajectory.

There are now three Mars Shuttles and two Cargo Shuttles, with three at Mars most of the time. No more are needed for several years. Two pairs of Ihabs now ply space between the worlds. The surface base now has considerable life support self sufficiency, extensive exploration capacity, and modest construction capacity.

Phase 3’s goals are to expand the life support and construction capacity so that the base can carry a greater share of the effort to expand Martian facilities. This requires launching a third Ihab each time, expanding the transport capacity to 12 and the surface population to 16 or more.

EQUIPMENT, PHASE 3

Expanded Cargo Transport Vehicle (ECTV) Now that Martian fuel is available, the 19 tonnes of payload launched with SEV propellant from Earth does not have to include the fuel needed to send it on a Hohmann trajectory to Mars; this can be provided at L1.
Cargo: 14.5 tonnes
Structure, avionics 0.5 tonnes
TMI Stage (an Interorbital Propulsion Stage) 1.5 tonnes
Aeroshield 2.5 tonnes (15% of total)
TMI fuel (from Phobos via L1) 5.0 tonnes

The TMI fuel has a large margin, allowing the stage to adjust the orbit after arrival at Mars.

Note that by building a transportation system and using SEVs, we are now able to land 60% of each 24-tonne payload on Mars, whereas the initial Mars Direct system using chemical propellant could land only 16-20%.

YEAR 11 (MISSION 5) Seven launches necessary

Launch 1: Ihab5, 3 tonnes extra consumables, 5-tonne SEV tank with propellant

Launch 2: Consumables (19 tonnes) and a 5-tonne SEV tank with propellant

Launch 3: ECTV with Hab (8 tonnes), greenhouse (6 tonnes), spares (0.5 tonnes), and IPS4 (1.5 tonnes)

Launch 4: ECTV with 6 tonnes solar panels and 8.5 tonnes of regolith moving and processing equipment, with 5-tonne SEV tank and propellant and IPS5 (1.5 tonnes)

Launch 5: ECTV with 8 tonnes of chemical and plastic synthesis equipment and 6.5 tonnes of equipment for Phobos (solar panels, more drilling equipment, another docking pad), with 5-tonne SEV tank and propellant and IPS6 (1.5 tonnes)

Launch 6: 7 tonnes of refurbishment supplies for Ihab1 and Ihab3, 12 tonnes LOX/methane fuel, and a 5-tonne SEV tank with propellant

Launch 7: 12 astronauts. They fly to L1 in a preexisting taxi vehicle using 30 tonnes of Phobosian propellant and carrying 4 tonnes of ecological supplies (fish in fishtanks, rabbits, chickens, seeds, seedlings, etc.).

Total mass going to Mars with astronauts: 19 (launch 1) + 19 (launch 2) + 4 (launch 6) + 16 (Ihab 1) + 16 (Ihab 3) + 17 (Mars Shuttle1) + 17 (Cargo Shuttle 1) = 108 tonnes, requiring 36 tonnes of Phobosian LOX/methane (note that the refurbishment supplies in launch 6 replace some of the mass in the Ihabs and thus does not increase their mass). The three landers require 15 tonnes more, and the 12 astronauts and taxi 30 tonnes more; total 81 tonnes (the previous mission flew 70)

Launches 1-3 propel themselves to L1. The astronauts fly up as well.

The central docking “cube” is arranged as follows: Ihab1 and Ihab3 opposite each other; Ihab5 and Mars Shuttle2 opposite each other; Cargo Shuttle1 with nothing opposite it (it will occupy the spin axis). The three habs and two shuttles aerobrake separately and rendezvous in a high Mars elliptical orbit. Four fly to Phobos in CS1 and remain in the hab there for two weeks doing routine maintenance and exploring the moon. MS2 and eight crew fly to the surface. A week later, the other Mars Shuttle on the surface goes to Phobos to retrive the crew there (if it has mechanical problems, MS or CS1 can fly them down).

Once the ECTVs arrive, the shuttles fly up and bring the cargo down to the surface. The cargo of launch 5 includes items for Phobos; a crew flies up, flies it to Phobos, sets it up, refuels, and returns to the surface.

With 15 astronauts on Mars, exploration continues apace but considerable more human resources are devoted to chemical and plastic synthesis and metal refining. Methane and carbon monoxide are starting materials for many plastics and metal carbides (which are liquid at reasonable temperatures and easy to pour and cast). After four years the base can make metal buildings, plastic greenhouses, furniture, and many other items.

YEAR 13 (MISSION 6) Six launches necessary. A repeat of Mission 5, except Launch 4’s regolith moving equipment is replaced by more automated supply carts, and Launch 5 carries an 8-tonne hab and a Moonlet Fueling Plant to Deimos. The Mars Shuttle visits Deimos for a month when the cargo from launch 5 arrives, deploys the fueling plant, sets up the hab, and explores the moonlet.

Dirt tracks now circle Mars near the equator and extend to the north and south polar regions. A track now runs the length of Valles Marineris and to the top of at least one of the Tharsis volcanoes.

Number04 · 2002-09-30 13:17:36

oh wow...

that's alot of writing.

:0

not to be mean, but we can have the best ideas in the world, but how are we going to get people to hear them?

Unless you're a NASA CEO or something.....

RobS · 2002-09-30 18:44:14

Thats a good question. I wrote all this mostly for my benefit, and I hope the benefit of others on this forum. In some ways, this may help answer a lot of questions others have posted elsewhere. And it helps me to play through the entire scenario and make sure it works. Increasingly, I think Robert Dyck is right: there's not going to be a heavy lifter for a long time. Let's hope the successor vehicle to the Space Shuttle is designed to be flown in two modes: manned, reusable mode and unmanned, cargo mode. The latter could push far more to orbit. If not, the Space Shuttle lobby will kill a heavy lifter program in order to protect their program.

Also, the Space Shuttle gets much cheaper if it is flown more often. The fixed costs are several billion per year and each mission actually has unique costs of about $100 million each. But the several billion, divided among six or seven flights per year, makes the average flight prohibitively expensive. If the flight rate got up to 12 per year, or even 20 per year, the launch costs would be much better. But right now there is no demand for so many shuttle launches. If a moon and Mars program is added on top of the ISS, there would have to be 12-15 flights per year and the unit costs would drop a lot. So the question is, can you go to Mars using the Space Shuttle? I think the answer is yes. But because of the need for on-orbit assembly, you get the same potential explosion of costs that hit the International Space Station.

So I hope my postings help all of us think about the problems of sending people to Mars more thoroughly.

-- RobS

Phobos · 2002-09-30 19:50:48

Robs, you've been inspired. Actually I like your plan better than Zubrin's. Assuming we can pull off the agricultural and Phobos untilization feats you mentioned, it would probably prove easier and cheaper to keep a manned Mars base alive than a Moon bound one. And I also agree that its best to design these missions around launchers that actually exist at the moment if possible. Hey, have you thought about writing a book, I'll buy it.

RobS · 2002-09-30 23:57:48

Well, this does inspire me to write a novel, and I may do that! Seriously, though, I may try to write this up better, but to do that, I need help. My plan has problems:

1. Can you armor the bottom of a vehicle with a heat shield, still use engines mounted on the bottom without destroying the heat shield (maybe doors can open in it?), and then reuse the heat shield. Reuse of the heat shield is essential for multiple use; if nothing else, the craft has to aerobrake at Mars and the Earth.

2. Exactly what do we need, in terms of equipment and the mass thereof, to make plastics, synthesize chemicals, refine metal, and work metal? Does a Mars base need 100 tonnes of stuff and 20 people to do those things, or can 3 people do those things with 16 tonnes of stuff?

3. How safe is it, really, for four people to set out across the Red Planet in two pressurized rovers, with a supply cart tagging along behind, bulldozing routes as they go?

4. Are the masses really adequate? The exchange Robert Dyck and I had illustrate the difficulties of determining the masses of things, even basic things like solar panels.

Anyway, help! Ideas are needed.

-- RobS

Mark S · 2002-10-01 07:42:10

Rob, have you considered putting your plan on the web? If you were to share it with others outside this forrum it might light a candle under NASA's butt...

24-tonne launch vehicles would be the best idea for now. The problem with using the shuttle for anything, aside from its high fixed costs, is the small diameter of its payload bay. Using an EELV like the Delta IV heavy or the less-hyped Atlas V heavy would make more sense because these rockets use 5m payload shrouds. Of course, someone could always adopt my idea of making an even bigger EELV by clustering seven Common Booster Cores...

One last question: did you ever consider nuclear power for the mission? I believe that a 400 kW reactor would have a lower mass than the equivalent solar panel for the electric transfer vehicle.

RobertDyck · 2002-10-02 00:31:47

I have another figure for you. The Glenn Research Center is continueing work to improve ion engines. Their web site has some papers that will be presented at this year's AIAA conferece. That includes work on a high power, high specific impulse ion engine. Only preliminary tests of the big 50cm ion engine at 9.9kW were done, but projected performance at full power is impressive. They expect to get a specific impulse of 8300 second at 30kW, and the engine is designed for 10 years continuous operation.

RobertDyck · 2002-10-02 01:38:58

Materials can be made in a number of ways. For example, manufacture of plastics is relatively simple if you choose a simple plastic such as polyethylene. The first step is to produce carbon monoxide using the reverse water-gas shift (RWGS). The RWGS reaction is:
H2 + CO2 -> H2O + CO
Hydrogen and carbon monoxide can be reacted in the presence of an iron based catalyst to form Ethylene:
2 CO + 4 H2 -> C2H4 + 2 H2O
Polyethylene (PE) resin is a simple plastic. It is formed by polymerizing ethylene. The chemical formula is [?CH2?CH2?]n where n is the number of units. Polyethylene has two variations: Low Density Polyethylene (LDPE) either has random branching or 4 to 6 carbon atoms attached randomly along the backbone. High Density Polyethylene (HDPE) is a long polyethylene molecule without any side groups. This permits the molecules to pack more tightly, resulting in slightly higher density.

HDPE is formed using a titanium/aluminum catalyst in 1-10 atmospheres pressure at 50?-100?C. LDPE is formed using a free radical initiator in 2000 atmospheres pressure at 200?C. LDPE is lighter but weaker, has a lower melting temperature and is transparent; it's used as sandwich bags. HDPE is opaque; it's used as milk jugs and plastic grocery bags.

A small facility could produce low volumes of plastic. The moulding equipment would probably be bulkier than the plastic synthesizing plant. A small PE synthesizing plant could probably be built the size of a refrigerator.

Gibbon · 2002-10-02 04:48:47

you could always hope and pray the HighLift Systems gets off their bums and makes their elevator a reality. It would drop the cost of your mission dramatically.

http://www.highliftsystems.com/

RobS · 2002-10-03 13:39:36

Thank you, Robert, for the information about an ion engine with a specific impulse of 8300 seconds. Incredible! Just what we need, to go to Jupiter and Saturn and beyond. But what do you know about electrical requirements? I gather if you fire your ions out the back at twice as much speed, it takes much more than twice as much electricity to do it. Right now with a specific impulse of 3,000 seconds, it only takes about 2-3 tonnes to push 16-19 tonnes of cargo to near escape. I am not sure it helps much, if we reduce the propellant to 1 tonne and increase the mass solar panels by 5 or 10 tonnes! Hence my question about the efficiency of these sorts of engines.

The visualization of a small chemical synthesis plant being about the size of a refrigerator helps a lot. The mass can't be much in a volume like that, either; maybe 1 tonne. But how much can something that size make? Ten kilograms of something a day? That might be plenty if you can accumulate the material; that's 3.6 tonnes per year.

-- RobS

RobertDyck · 2002-10-04 01:58:30

The reason I mention further advances is to propel the big payloads, a manned spacecraft or cargo ship to Mars. Deep Space 1 was supposed to pass Mars on a gravity assist to a comet, but the mission was changed after the thruster developed problems preventing the top 3 throttle settings. But DS1 was only 440kg total launch mass. A larger spacecraft will require stronger thrust. NSTAR only had 92 milli-Newtons of thrust at 2.3kW and 3100s Isp. The 50cm thruster produced 178mN thrust at 9.9kW and 5210s Isp. They projected 8300s Isp at 30kW, but didn't publish the thrust. They also experimented with increasing the power to a 30cm NSTAR ion engine. The result was 165mN at 6.5kW and 5600s Isp.

You have to realize just how weak that thrust is. 1 Newton of thrust can accelerate 1kg at 1 meter per second squared. Earth's gravity is 9.8m/s^2 so it takes 9800mN to accelerate 1kg at 1 gravity. 165mN would accelerate 440kg at 0.000209m/s^2. That would only add 18m/s delta-V per day of continuous thrust. At 165mN thrust for a 24 metric tonne spacecraft, it would produce 0.000006875m/s^2 acceleration, which would add 0.594m/s delta-V per day. Escape velocity for Earth is 11.2km/s. Orbital velocity at 200km circular orbit is 7.78km/s. That requires 3420m/s additional velocity, which at 5600s Isp would require 10.97t propellant and at 0.594m/s per day would require 5757.5 days = 15 years 9 months 9 days. That is just to spiral out from LEO to escape Earth.

NSTAR required 2.5kW from the solar panels to provide 2.3kW to the thruster. That is due to conversion losses from solar panel voltage to the high voltages required for the thruster. To provide 6.5kW that would require 7.065kW from the solar panels. The solar panels I mentioned before with a single layer of carbon fiber substrate would provide 277.7W/m^2 end-of-life in Earth orbit and mass 2.25kg/m^2. Total mass of the solar panels would therefore be 57.24kg or 0.05724t.

At 3100s Isp it would require 16.037t propellant. That only leaves 7.963t for tanks, engines, solar panels, and payload. Solar panels would mass 20.25kg or 0.02025t. The lower Isp costs you 4.487t additional propellant but only saves 0.03699t in solar panels.

Increasing the number of thrusters would not change the fuel load required, just the total mass of thrusters and solar panels. Increasing thrusters would decrease time to get there. 30 high-power NSTAR thrusters could achieve escape velocity in 191.9 days. Mass of each engine is 48kg including thruster, Power Processing Unit, Digital Control Interface Unit, propellant feed system, and cables. That would require 1.440t for engines and 1.7172t solar panels for a total of 3.1572t. Since standard-power NSTAR thrusters only generate 92mN thrust, you would need 54 of them to achieve escape velocity in 191.2 days. They would require 2.592t for engines and 1.0935t solar panels for a total of 3.6855t.

The standard-power thruster not only require more propellant, the fixed mass is greater. I don't have thrust or mass figures for the 50cm thruster, so I can only calculate propellant: 8.105t. That is 2.865t less than the high-power version of NSTAR. These figures are just to escape Earth orbit. It will take more propellant to go to Mars. Someone please tell me if these calculations are off.

RobertDyck · 2002-10-05 11:46:33

Yes, my grandfather was a farmer and my father was a welder in the heavy equipment shop of the railroad. However, to ensure he was the best welder there, my father got a community college engineering diploma. My mother's parents were also farmers for a while, then operated a restaurant before my maternal grandfather started his career as a carpenter and general contractor building houses. On my mother's side I was the first grandchild to attend university. My mother's training was accounting (RIA now called CMA), but became manager of a computer department; however she never attended university. Although my grandfather was the best house builder in town, he depended on my grandmother to manage the finances; he couldn't balance a cheque book on his own. Your joke hits a little too close to home.

The figures in my calculations are a little over simplistic. The specific impulse (rocket fuel efficiency) figures are exact, and are for engines available now. The thrust, mass, power requirement, solar panel specifications, and carbon fibre structural mass are also exact. Propellant mass to achieve that delta-V (change in velocity) is also exact, and based on a calculator that includes continuous reduction of mass as the spacecraft expends propellant at the specified specific impulse. However, the delta-V calculation is crude. The correct method is to calculate potential energy divided by mass. A higher altitude orbit has lower velocity but higher potential energy. The calculation I did should be relatively close because the starting orbit is very low.

Furthermore, up to an altitude of 800km there is still a little atmospheric drag. The exact amount of drag and exact altitude it extends are dependant on solar flares: additional solar wind impacts the upper most atmosphere causing it to expand. Solar wind/atmosphere interactions involve the Earth's magnetic field resulting in complex plasma calculations. Attempts to predict that are more difficult and less accurate than the weather. At this point we can only look at "space weather" reports.

RobS · 2002-10-05 23:01:41

I had trouble following your calculations because I wasn't sure your starting mass (I guess 24 tonnes; it's a nice round number, isn't it?) or how much cargo you were pushing. The overall masses for the panels and thrusters look similar to the assumptions of Michael Duke's "Lunar Reference Strategy" paper that I used as a baseline for developing Mars-24.

Regarding the total delta-vee necessary; I have heard that ion engines generally require about twice the delta-vee of chemical rockets because of all the gravity loss caused by leaving a planet slowly. I suspect launching to near-escape requires at least 50% more energy because one is circularizing ones orbit constantly as one moves upward. Among other things, that means one briefly travels through a circular geosynchronous orbit, and it requires a delta-vee of 4.1 km/sec to achieve (2.5 km/sec to go from low earth orbit to a geosynchronous transfer orbit, then 1.6 km/sec to circularize). I arbitrarily assumed that L1 (near-escape) required 4.5 km/sec to achieve rather than 3.2 km/sec.

Robert, we have similar background in some ways. I was raised on a farm and was just the second member of my family on my father's side to go to college. My father built aircraft engines but not as an engineer; he was the foreman of an assembly line. Then he quit that work to go from part-time farming to full time. I should add that my mother's father homesteaded in Manitoba, probably in the 1890s, before settling in New England and becoming an insurance executive.

-- RobS

RobertDyck · 2002-10-06 11:05:47

Thanks for replying, RobS. The problem with doubling the energy to spiral out occurs if you apply continuous thrust. That does maintain a circular orbit. Instead, you can apply thrust just at the perigee to raise the apogee. The ironic thing about orbital mechanics is that if you apply thrust at the apogee, it will raise the perigee. Applying short bursts of thrust just at the perigee will create an elliptical orbit with the perigee staying at 200km and raise the apogee with each orbit until the spacecraft escapes orbit. The problem is that will take more time. You're right; the time calculations were based on continuous thrust so this would take significantly longer.

For a couple years I have tried to find a way to direct thrust so it can be applied continuously while raising just the apogee. Because thrust would not be perfectly tangential to the flight path it would be less than 100% efficient. Applying thrust at the apogee, however, should be more effective because applied thrust is additive. When you add the thrust while the spacecraft is travelling slowly, it will have proportionately greater change to velocity. As the spacecraft descends to its perigee, all velocity will increase including the incremental thrust that was added at the apogee. Think of it as gravity assist while still in Earth orbit. The only way to prove this could be effective is to do the math. I'm afraid I need a calculus tutor.

RobS · 2002-10-06 23:37:20

That's a fascinating idea, but alas, I flunked calculus, so I can't help. I think ion engine are always assumed to work continuously and to raise perigee and apogee constantly, wastefully spiralling out of low orbit.

One possibility would be adding a tonne of energy storage system, probably fuel cells, storing up your solar power and using it all to thrust the ion engines at maximum only at perigee. That might work reasonably well when the apogee isn't too high. But as the orbit gets more and more elliptical the percentage of time away from perigee gets longer and longer and you'd have to store a bigger percentage of your total energy.

I am not sure why people aren't thinking of deploying big mirrors to put more light on their solar arrays. The high efficiency gallium arsenide cells operate very well at high temperatures and insolations; I think I saw 25 times normal insolation is okay for them. A mirror deployed in earth orbit could be a hectare in size (100 meters square) and weigh almost nothing. It seems to me with mirrors one could easily create megawatt solar arrays that are small. One could even operate such arrays half decently at Saturnian distances from the sun; the mirrors would just have to be bigger. This would give you so much power, you could just turn the ion engine on and off to make the orbit elliptical, and you'd still have a reasonably short acceleration time.

-- RobS

nebob2 · 2002-10-07 22:31:11

Soem people have considered using concentrators

Advanced Propulsion Concepts

Ion engines are very efficient, but their thrust is far too low for human spaceflight. A solar clipper would be good for cargo though, cheep and efficient.

Why not use a more powerful plasma engine then an ion thruster? You really want to limit flight times for humans. Other forms of plasma propulsion also ofer high Isp, many in the 3000-7000s range, with thrust ranging from 100N for MHDs, 2000N for VASIMR, or 4000000N for the more radical EPPP. Even if you do use an ion engine, powering it up from 400kw to Mw size would be advisible.

RobS · 2002-10-10 15:37:27

Thank you for the web page about advanced propulsion concepts. I did not use anything of this sort because (1) I didn't know much about it, and (2) I was concentrating on shorter term technologies. So far, the largest function ion engine in space uses only 2 kilowatts and the ones being designed are in the 10s of kws range, not even 100s, which is what Mars-24 would need. The more advanded propulsion systems you are suggesting are probably farther down the time line. Of course, if it takes 40 years to send people to Mars, we will probably be using the more advanced systems!

-- RobS

nebob2 · 2002-10-10 16:08:45

There was a 200 kw ion engine from the 60's shown on the site, which is a lot closer to what you need. Ion engines, because of their carefully spaced grids, can be difficult to scale up. Hall thusters would be easier to scale, but are not quite as efficient. The others could take a decade or so of concerted development to make a large reliable engine suited for human spaceflight, their higher plasma temperatures complcate matters but provides high thrust, but since no one is even thinking about a mission until 2014-18, they could be used in time. In the final design, a small nuclear reactor could boost the ion engine from 100's of kws to 1000's, and with electric engines, more power is good.

Austin Stanley · 2002-10-12 17:10:39

One problem that occured to me is that the reliability of these components can probably not be counted on over a very long period without regular maintance and replacment which may be difficult to impossible for some of these craft. You shouldn't count on a object you launched 14 years ago to be highly reliable today. In fact, it will probably have already failed. Habs will spring leaks, engines will break, life-support and other systems will all breakdown in various ways. The craft and habs used in this program will all have to undergo maintance and more than likely replacment, which should be counted for.

Also, since this program extends over a long period of time. I think it would be realistic to assume that over this period of time technological advancments will make various upgrades possible. Any program extending over such a long period of time should hopefully have some hand in directing that technological advance would occur (especialy since this would be by far the most expensive program NASA would be undertaking at the time).

Third I feel strongly that utilising nuclear power can add so much to a martian mission that it should be included in the cards at some point, at least at some point. A nuclear reactor on the surface, and NTR to deliver crew to mars as well as to lift objects once there to orbit (and back perhaps).

Phobos · 2002-10-12 20:23:44

You shouldn't count on a object you launched 14 years ago to be highly reliable today. In fact, it will probably have already failed. Habs will spring leaks, engines will break, life-support and other systems will all breakdown in various ways. The craft and habs used in this program will all have to undergo maintance and more than likely replacment, which should be counted for.

Very true. If we intend to use the habs for years on end it'll be necessary to make it easy to access and replace virtually everything in the hab, particularly mechanical components. I hope they don't make the habs like they did my Mazda where you practically have to pull out the whole damn motor just to replace the starter.

nebob2 · 2002-10-12 23:33:06

Making virtually everything in the hab accessible is more then a long term solution, it is a required safety element. If the crew has to survive on a hostile world for 500+ days, they better be able to repair broken parts. It is a matter of survival. To assume that nothing will go wrong is to assume too much. Look at the early designs for interplanetary ships. They included a repair shop and machine tools, something you won't find in anyone's plans today. And they planned for flight times shorter then or equal to Mars-24's. While it unlikely you would need to do major repairs to the ship itself, carrying extra spares, or the tools to make them, or jury-rig them, on the ground should be considered. It may be more mass, but we are talking about people's lives here.

Phobos · 2002-10-13 12:06:23

They included a repair shop and machine tools, something you won't find in anyone's plans today. And they planned for flight times shorter then or equal to Mars-24's. While it unlikely you would need to do major repairs to the ship itself, carrying extra spares, or the tools to make them, or jury-rig them, on the ground should be considered. It may be more mass, but we are talking about people's lives here.

You know, come to think of it, if we do setup a network of habs on the surface that serve as a base, it might not be such a bad idea to design a special hab that would serve as a workshop that would be loaded with critical spareparts, tools, and manuals. Actually, I think it would be a little silly not to have something like that. It reminds me of when I used to work nights in a foam extrusion plant. They had a huge maintenance department that resembled a hardware store. If a machine broke down there was no question they had the parts to repair it on the fly! Having a "maintenance department" on Mars only makes sense to me. When they design the habs they should try to use the same types of parts as widely as possible so their easier to fix. Try to use the same sized screws, same sized hoses, etc. as far as possible.

Austin Stanley · 2002-10-13 14:40:31

One problem however, is that for many breakdowns repair will simple be impossible either on Mars, or in space. A leak in the hab, for example is probably an easy fix. Malfunction of the propulsion or lifesupport maybe impossible to fix. Replacing the subsystem in some cases, such as propulsion may be impossible. Maintance in orbit will obviously be more difficult. While a "maintance hab" is a good idea, at least at one point. I think much of the equipment will probably be prohibtably heavy as would the stocks necessary for the equipment. However, this repair equipment could be used to build new equipment for new stuff which would always be good. Universal componets is of course and excellent and always a good idea.

nebob2 · 2002-10-13 15:55:04

Most concepts only had a limited number of spares. New spares could be manufactured, as raw material would take up less volume, but would require more equipment. Last time I looked, the surface hab in Zubrin's plan carried a 4 tonne margin for spares and contingency, with a .9 tonne spare and contingency margin on the TEI vehicle. Since two habs are to be sent to the surface, placing extra spares and tools in the initial one would be an effective use of mass, replacing expendibles used for transit in the manned hab. If something major breaks they might not be able to fix it, that is a risk one must take. Having some way of exiting the TMI hab for an EVA to allow small repairs, check the heat shield before aerobrakeing, etc. might also be useful.

RobS · 2002-10-13 22:45:33

I agree that any plan for settling Mars needs to have plenty of spares and margin, with a machine shop of some sort among the early cargo flights. Any plan also needs backups; I think a spare hab is always a good idea (i.e., if a hab accommodates 4 and you have 4 people on Mars, you need to have space for 8; when your crew expands to 8, you make sure you have a third hab and room for 12; etc.). This is another argument in favor of settling one spot on Mars, rather than landing at a different spot every two years. In fact, I think it is an argument that the first mission ought to involve two vehicles capable of accommodating four each, but flying only three each; that way if a hab or shuttle breaks, everyone can squeeze into the other one. Once confidence in the equipment builds, one could then fly four in each vehicle.

Multiple possible use of equipment is also wise. For example, a greenhouse might be able to serve as temporary housing if a hab has a problem. Same with machine shops and garages. If one has two habs and two greenhouses, it might be wise to connect them in the form of a square, so every module has escape routes at either end. As more modules are added, they should always be connected, if possible, so that they always connect to other modules at each end.

Someone stressed the value of nuclear power. I quite agree. I put together Mars-24 without it to see whether it is possible. It appears to be possible. But I agree, nuclear is easier. It may not prove politically practical.

Robert Dyck again stressed the problem of using L1 because it requires circularization. If it requires orbital circularization, I agree a highly elliptical orbit is better. But I have not yet seen anything suggesting it requires circularization. It seems like it should, but L1 is not a real orbit; it is a point where gravity cancels out. It may also be easier to get to it by flying to the moon and circularizing into a high orbit around the moon just short of L1, then raising the orbit to L1. And L1 is a popular idea among the experts; as we recently saw in Space.com, there is a big proposal from NeXT to build an L1 station as a staging point for lunar and Mars exploration. I am assuming they know something we don't, but I wish I knew what it was! Objects often do not stay "at" Lagrange points, but wander in complicated orbits around the point.

-- RobS

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#1 2002-09-29 23:07:51

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#2 2002-09-30 13:17:36

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#3 2002-09-30 18:44:14

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#4 2002-09-30 19:50:48

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#5 2002-09-30 23:57:48

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#6 2002-10-01 07:42:10

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#7 2002-10-02 00:31:47

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#8 2002-10-02 01:38:58

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#9 2002-10-02 04:48:47

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#10 2002-10-03 13:39:36

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#11 2002-10-04 01:58:30

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#12 2002-10-05 11:46:33

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#13 2002-10-05 23:01:41

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#14 2002-10-06 11:05:47

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#15 2002-10-06 23:37:20

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#16 2002-10-07 22:31:11

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#17 2002-10-10 15:37:27

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#18 2002-10-10 16:08:45

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#19 2002-10-12 17:10:39

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#20 2002-10-12 20:23:44

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#21 2002-10-12 23:33:06

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#22 2002-10-13 12:06:23

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#23 2002-10-13 14:40:31

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#24 2002-10-13 15:55:04

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

#25 2002-10-13 22:45:33

Re: Mars 24 Project - To Mars with Existing Commercial Rockets

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