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Dunno, Louis, might work pretty good. It'll need much bigger reflectors, since the solar flux is about half out at Mars. Not as cloudy as here (excepting dust storms), which is good. Losses to the more extreme cold are bad, but the more extreme cold may make the engine more efficient in its cooling phase. 34% efficient ain't nothing to sneeze at. Giant Rankine-cycle (steam turbine) power plants here are at best about 40-something-% efficient. Size plays a role, too. What's in ships is 30-something-% efficient.
I'd be awfully careful about pinning all hopes on 3-D printing. I know they can print metal parts now, but the structural properties are no better than sintered metal forms, which are really, really lousy compared to real forged forms. Doesn't matter what metal you talk about. I'd never make a tool like a wrench, or especially a pressure vessel, by 3-D printing. Not anytime soon, meaning next several decades.
GW
Not sure it needs bigger reflectors. The system referenced produces enough power for 23 homes...you simply get maybe half the power on Mars - enough for the equivalent of 11.5 homes!
Well perhaps the 3D printer will just give the mould which can then be used to shape the metal.
Just been reading up on the manufacture of solar reflectors.
http://en.wikipedia.org/wiki/Solar_mirr … _substrate
Protective glass should not be a problem on Mars. I also note that Mars meteorites found on Earth have contained aluminium so one would hope that deposits of aluminium would allow for construction of the reflectors.
Looks like we know aluminium is definitely there:
This system for generating electricity using solar reflectors and a Stirling engine sounds like it could be a great solution for generation on Mars:-
http://www.theguardian.com/environment/ … ity-system
Using 3D printers coupled with basic steel production - I think a small Mars colony (numbered in tens of people) could manufacture the solar reflectors, which look they consitute the bulk of the system. They might even be able to produce stirling engines as well.
True but they don't need everything at once.
In the initial stages, the base will be tiny - there is unlikely to be a population of more than 50 people max in the first 10 years . There will no shortage of cabling, PV panels, plastics and the like.
CO2 from the atmosphere is there for the taking, as is the solar radiation for power.
Water - obviously...no. 1 priority.
Silica, presumably, will be in abundance.
Iron ore to make tools.
A source of calcium carbonate would be good if they are going to make steel...
And we will never find everything a base needs in one place. The main things a base needs, I think, are water, nickel-iron meteorite, and perhaps copper (which is a widespread ore associated with basalt lava flows). The nickel-iron may be widepsread at the sand size and can be separated magnetically, so water is the key ingredient. I'd look for an equatorial spot with buried ice (easier to fly to Phobos and Deimos. easier to fly to any orbital inclination) and start there. There was a recent article about buried glaciers that appear to be sublimating away in Valles Marineris, so they are at an extremely low altitude, plus are on the equator.
There can only be one comment: pathetic.
No drive, no vision. What are they doing all this for? It's a whole lot of fandangling effort for very little gain.
We could have a functioning colony on Mars within 10 years if we wanted, and NASA could get funding from many other space agencies and other sources of funding if they really wanted to make it happen. They don't. At least, not in any way that suggests it is a priority.
The Humans to Mars Conference is being broadcast live over the internet right now at http://www.space.com/17933-nasa-televis … ce-tv.html . They just gave the new NASA plan for getting humans to Mars. They use SLS with a flight rate of 2 per year, a 100-kw xenon solar electric propulsion to preposition assets (3.5 year flight time!), a deep space habitat that provides a model for a Phobos habitat as well, a 23-tonne Mars surface lander/ascent vehicle (which can also take cargo down one way, such as a surface hab). They take humans to Phobos in 2033, to the surface for a brief visit in 2039, and a 300-day surface stay in 2046. The Mars lander is developed later because of costs, so the first flight just goes to Phobos and tests the deep space part of the mission. The Mars lander can also be used to land astronauts on the surface of the moon as a test in the early 2030s. The Mars lander can only get back to low Mars orbit, so there has to be a prepositioned stage there to get the crew back to Phobos (which will serve as the orbit base for all operations). The SLS assumes 110 metric tonnes to orbit, then 130 mt later. Launches are always in pairs; for example, a launch to get the SEP and a Phobos transfer stage (using hypergolics) into high Earth orbit, then a second SLS to get the Phobos hab and a TMI stage to the same high Earth orbit. For the crew, the first launch gets the deep space hab and TEI stage into high Earth orbit and the second launch gets the Orion capsule and TMI stage into the same high Earth orbit.
The entire idea is to keep the cost UNDER the current NASA budget, adjusted for inflation. ISS funding continues to 2028. The lunar surface program is a brief blip in the late 2020s or early 2030s.
They use supersonic retropropulsion to get the lander to the Martian surface and note that SpaceX has demonstrated this technology, but that was the only reference to SpaceX. There is no assumption of international participation, though it is assumed that will happen.
Quite a few Martian orbit rendezvous. That surprised me.
They are assuming SLS, of course, because Space X can't get 130 tonnes into LEO. If they can, the architecture can be changed.
Very interesting. Q and A is still going on.
NASA is a space exploration agency, not a space colonization agency. We're going to Mars to explore, first and foremost. Permanent human presence is a secondary goal. ISRU is important for the establishment of a permanent outpost, but it's not a justification for going to Mars.
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What would another rocket powered robotic vehicle tell us about Mars that all the other rocket powered robotic vehicles haven't already told us? We've done about as much as we can remotely. Sooner or later we need to land some geologists, meteorologists, and microbiologists to try to determine whether or not humans could conceivably live there. After a few mobile surface exploration missions, we can concern ourselves with establishment of a permanent outpost there.
We could cover thousands of square kilometres very easily and quickly with pitoless drones. They can land and take samples, and return them to base for detailed analysis. Much quicker and more effective than having big human crews in rovers (I presume you know how difficult and draining doing an EVA is) .
I realise NASA isn't a space colonisation organisation. That's why they are not going to be the ones to get us to Mars. Space X is. The most likely scenario is that Elon Musk will get us there - possibly with a "NASA badge" on the front.
I agree with most of what you say GW.
A few areas of disagreement:
1. Historically, exploration was a kind of survey of what was there. Even at the beginning of the 20th century maps of our planet still had substantial areas of "terra icognito". There is nothing like that on Mars now. We have a good, if rough idea of what is there already. But that is not to underplay the importance of a human presence to take exploration further - for one thing humans could control robot vehicles in near real time and speed up that whole process.
2. 100% self-sufficient is unlikely and not very desirable. My own studies suggest that the Mars colony could probably without too much effort sustain itself on a 95% (tonnage basis) i.e. importing 5% of the stuff it uses. Construction can use ISRU materials. Agricultural needs would be taken care of pretty quickly - so food and clothing could be taken care of in-situ. Power could be supplied from ISRU steam engines used steel or similar reflectors to concentrate solar power on boilers, which would then feed steam to engines to power the settlement. Things like turbines could be manufactured from 3D printers.
They would just need to import things like computers, 3D printers, space suits, medicines and medical technology. But after the initial wave of importation, these would reduce to maintenance levels. Probably most people on Mars would never get in a space suit - except in a touristy sort of way. They will probably just live in pressurised habs and pressurised vehicles.
That said, I think the colony will make so much money that it will be able to afford high levels of importation, so the real figure could be closer to 50-70%.
3. Let's take a hypothetical "Mission 2" - just think of all the opportunities for revenue earning from returned regolith and meteorites. Universities all around the planet will be desperate to get their hands on it. Then there are all the mini experiment packs they could take out on behalf of researchers around the planet...$100,000 per Kg. of experiment. Why not? That's before we discuss sponsorship - how much would Coca Cola or Toyota pay to sponsor the Mission and or an exploratory journey? How much would car companies pay to have mock-ups of their cars placed on Mars? How much would Mercedes pay to brand a Mars Rover?
I'm not a great fan of sponsorship, but in the absence of government funding, please don't underestimate the revenue that could come in.
Longer term the colony I think will be able to make huge amounts of money by: providing life support for a university campus near the base; hosting explorers from the various Space Agencies on planet Earth; exporting precious metals;
developing Mars-based industries e.g. Rolex watch assembly, luxury goods manufacture (e.g. gossamer like clothing and jewelry); supporting film and documentary crews; assembling art works (e.g. sculptures - possibly using 3D printers) on Mars; providing data storage e.g. maybe digitised versions of the World's Great Libraries; and "gap year" tourism.
History over the last millennium says that there are (crudely, and with overlap) 3 phases to “exploring” a new land. The ultimate goal was, is, and always will be, colonization if feasible. Depending upon available technology at the time, some places are feasible, others are not. That situation changes over historical time, just as the transportation technology does.
The 3 phases are (for lack of better names) exploration, adaptation, and colonization.
“Exploration” was, is, and always will be whatever efforts are required to answer two very deceptively-simple questions: (1) “what all is there?” and (2) “where exactly is it?” I mean them exactly as stated, word-for-word. That is not Texas slang. If you have not answered them, you have not “explored”, period. End of issue. That IS the lesson of history.
Our probes have not yet answered these questions on Mars, it generally takes men in-situ to do this, since we cannot yet build intelligent, self-aware robots. We NEVER EVER did it on the moon, although we are getting closer in the decades since Apollo. Apollo was almost nothing but flag-and-footprints nonsense. Almost.
“Adaptation” refers to some sort of base or settlement, where people are trying everything in (or out of) reason to figure out how to survive living off the local resources. A facility like this is invariably “life-supported” from home at first, and perhaps for quite a while.
It takes a long time to figure out how to survive in benign environments, much less the hostile ones. And Mars is nothing if not quite hostile to human life. The success rate in such experiments is historically rather low, but the flip side of that is that we have never failed before.
“Colonization” has an entirely different focus. You cannot do this until “adaptation” is successful. In colonization, what you are looking for is twofold: (1) population growth, and (2) whatever trade basis there might be for a local economy. You simply CANNOT successfully do that until you have successfully learned how to live locally 100% upon local resources.
The best of the colonial efforts half a millennium ago here on Earth successfully solved this trade economy thing. Those former colonies are prosperous nations today. The worst never did solve this economy thing, and so stayed in the resource extraction mode only, and those former colonies are third-world nations or borderline failed states today.
I have previously voiced serious concerns that there will be one, and only one, manned expedition to Mars, that is funded by any or all of the government space agencies on Earth. That’s been the history of the last nearly-a-century of government BS and failure, around the planet.
That being said, that first expedition had better land men on Mars. Screw the flyby and Phobos-only ideas. Period. Or else it will be multiple decades before anybody else ever goes. That’s just an unfortunate fact-of-life in the 21st century. Everybody needs to face up to it, too.
500 years ago, explorations were government-financed entirely, so that is still quite the appropriate model. But, “adaptation” ventures were usually jointly funded, public and private. Two examples are the Dutch East India Company, and the British East India Company. The long-term colonies were almost all privately-financed ventures.
What THAT says is that our first (and only) manned exploration mission had better leave behind some sort of an operating “adaptation” facility, and make joint funding available with the visionary private entities that might go back to Mars and use such a facility. If you do nothing but flag-and-footprints on that first mission, then returning to Mars is nowhere near as attractive to private entities, even the visionary ones. You just delayed things by more decades. Maybe a century. Or more.
It’s going to take a lot of time and a sequence of multiple crews at some sort of “adaptation” base, to really and practically solve the problems of “living off the land” on Mars. Expecting to see solutions to those problems, from one early mission, is unrealistic IN THE EXTREME. It NEVER EVER happened that way in the last millennium. And Mars is tougher than anything we ever attempted on Earth.
You will not know what the economic trade basis for successful colonization will prove to be, until those adaptation problems really are fully solved. Talking about that right now is just idle speculation. You gotta go and adapt first, before you know what local resources or products might actually be useful back home.
And, I warn for a second time, DO NOT plan your colony’s economic system on nothing but simple resource extraction. Nothing in history suggests that to be a successful economic model long-term, although nearly all the colonies started out that way.
Having said all that, NOW do you all understand why I have such heartburn with most of the mission architectures I see proposed here, or at NASA, or anywhere else, for that matter?
GW
Well he must be thinking in terms of using some sort of parachute system I guess...I've never seen anything suggest you could land 11 tonnes on 3 tonnes of fuel.
Looks like the Apollo lander (including the ascent stage weighed in at about 15 tonnes) and had over 8 tonnes of propellant on board. So - over 50% was propellant. Are there more powerful propellants now? Maybe that would explain the difference?
http://en.wikipedia.org/wiki/Apollo_Lun … cent_stage
I am not sure what you are saying, Louis, but I looked up Zubrin's article and here is a correction:
"The SpaceX Falcon Heavy will have a launch capacity of 53 metric tons to low Earth orbit. This means that if a conventional hydrogen-oxygen chemical rocket upper stage were added, it could have the capability of sending about 17.5 tons on a trajectory to Mars, placing 14 tons in Mars orbit, or landing 11 tons on the Martian surface. . ."
My comment about 13 tonnes launched to TMI comes from Space X's calculations, and I guess they were not using hydrogen-oxygen propulsion. Zubrin figures, with hydrogen-oxygen for the TMI stage, 17.5 tonnes to Mars, 14 tonnes into orbit, and 11 to the surface. That means two could send 35 tonnes on its way to Mars. That's a lot of tonnage for a descent/ascent vehicle. 11 usable tonnes to the surface is a lot for a hab, for a pressurized rover and supplies, etc. So I think it is well worth our while, assuming we can land things reliably and accurately, to land 2 cargo landers before we land people, so they really DO have the equivalent of a base. Or, we might want to think in terms of pairs of Falcon Heavy launches for everything; one large cargo lander, one transit hab and TEI stage, and one ascent/descent vehicle. That'd be 6 Falcon Heavy launches altogether
I think at this point we are still not certain about the accuracy of landings because Mars has an atmosphere. Apollo 12 could land close to he Surveyor, but the circular error probable of the unmanned Mars probes is tens of kilometers. Zubrin worried about landing accuracy as well. We're still even sure we CAN land larger things on Mars, let alone the accuracy.
That's why you have transponders on the surface and appropriate thrusters on the lander.
IF you have enough retro-rocket thrust there is no reason why you can't land sizeable payloads on Mars.
I suppose we can come up with a half dozen scenarios--however unlikely--where the crew might need more than 24 to 48 hours in the ascent or descent vehicle before docking or rescue. So I am very worried about the idea of a minimum-mass vehicle.
I think Zubrin calculated that with a hydrogen-oxygen third stage, a Falcon Heavy could launch 13 tonnes on a Mars trajectory and presumably can land about 8 or 10 tonnes on the surface. That means two Falcon Heavy launches can land about twice that much; one would launch a trans-Mars injection stage and the other would launch a smaller stage and the payload. So even with a non-reusable Heavy, $200 million will get into LEO 18 to 20 tonnes destined for the Martian surface. So we certainly can get a pressurized rover and a good-sized hab on the surface. For that reason, I think we can afford a decent sized rover, a reasonable sized pressurized rover, and a reasonable sized ascent/descent vehicle.
But I may be wrong.
"land about 8 or 10 tonnes on the surface" out of 13 tonnes - really? That sounds a bit counter-intuitive.
I really can't understand why you keep talking about "landing off target". I can't see how that could happen, unless there was a serious malfunction of the lander - the like of which never happened on the Apollo missions. The lander would be tested and tested again - hundreds of times. There is no reason to think it will land off target. Using your logic we would have to started "safety planning" for all sorts of unlikely events.
Keeping the crew alive is a top priority but effort needs to be concentrated where it is effective in guarding against real risk.
There's no reason why a pressurised Rover shouldn't also be provided for use post-landing. But rather than building some huge monster, we could have a small 2 or 3 person vehicle.
Anyway, exploration should not be a major priority for Mission 1. ISRU experimentation should.
We could probably get plenty of exploration value using a pilotless drone - maybe rocket powered - steered by the first colonists.
Put another way, under normal operating conditions, the crew is aboard the descent/ascent or descent and ascent vehicles for less than 24 hours. The minutes spent during descent and ascent are critical to the outcome of the mission, but should we devote a major portion of available funding to those few minutes because of what might happen afterwards or account for what might happen afterwards with the design of the rest of the mission hardware?
If there's contention about what our general landing accuracy on Mars is or contingency scenarios that have to be accounted for, should we design a propulsively landed solution that necessarily has significant mass and complexity, or should we develop surface transportation solutions that can retrieve our astronauts if they land off target? What solution has the lowest level of technical complexity, small single man capsules with pressured rovers to retrieve astronauts who land off course or a multi-person propulsively landed capsule that lands the entire crew in one operation? What problems or contingency scenarios does landing the entire crew at the same time solve?
Obviously the propulsively landed solution is capable of some degree of course correction to land as near to the target as feasible, but what happens if even that solution lands a little off target? For example, let's say that a propulsively landed multi-person capsule lands 10km from where intended. Does that mean our astronauts have to carry the oxygen and water to walk back to the habitat module? I think you still need a rover of some kind to retrieve the astronauts. You don't need a pressurized rover and perhaps don't even need a rover that carries the astronauts, but you still need a small robotic rover to carry oxygen and water.
For any real surface exploration effort, a pressurized rover that provides some measure of shielding against SPE's is a requirement. Supposedly, we're going to Mars to explore. A substantial pressurized rover is therefore a requirement if we're to accomplish that stated mission objective.
Establishment of a base on Mars is a far future goal that would require some level of cooperation between the various space agencies. It would be really nice to have, but it's not required for surface exploration and shouldn't stand in the way of a surface exploration mission.
I agree Ceres is fascinating and should perhaps be destination no. 2 after Mars. Presumably at times it will be pretty "close" to Mars.
http://upload.wikimedia.org/wikipedia/c … 150414.jpg
Ceres
http://news.brown.edu/files/article_images/Mars1_0.jpg
Mars
Which is easier to land astronauts on?
Which has more water?
Could we grow plants on Ceres? How about Mars?
Mars Direct
Ceres Direct
What is the difference?
Could rocket fuel be produced on Ceres?Seems to me, we only recently got to know Ceres as a world as opposed to a dot in the sky, how does this new perspective affect things? Could we fund a manned mission to Ceres at the same cost as a Mars mission. I also note that there are more frequent launch windows to Ceres than to Mars, as Earth catches up to Ceres and aligns itself more often.
http://www.teslamotors.com/powerwall
This will most definitely be the solution for isolated dwellings/research stations on Mars I think.
Couldn't agree more GW, it's all doable now with current technology. What's missing is political will. Musk may well subsitute entrepreneurial will for that. We will see.
The ascent vehicle/descent vehicle safety issue can be avoided, but not at minimum mass. I think it is wrong to let minimum-mass as a constraint drive you into a corner with no outlet.
It is fairly easy to show that a single stage chemical rocket vehicle capable of a two-way trip to the surface and back from LMO is quite possible. Its only drawback is low payload fraction, meaning many tons of fueled vehicle must be sent to Mars to land a handful of tons on the surface, and still ascend. There is no way around that.
But the advantage is that this vehicle could be refueled either on the surface or in LMO, and thus be reusable. It could make many such trips, very important for constructing some sort of base on that first mission. This becomes very attractive indeed, if in-situ propellant production proves practical at massive production rates.
The safety issue also goes away if you bring more than one of these landers to Mars with you. All it needs is a temporary-occupancy abort capsule for its command cabin, in which the entire crew rides. The other vehicle(s) can be rescue birds if descent or ascent abort becomes necessary. That capsule looks an awful lot like Red Dragon in its characteristics, actually.
The only problem with all of this is the mass of payloads that must be sent to Mars. Those are large enough to require assembly in LEO, not direct shots to Mars. No way around that, either.
But as launch prices have fallen from the $25,000-30,000/lb we had with shuttle to the $2500/lb we have with Atlas-5 and Falcon-9, and to the $1000/lb we will soon have with Falcon-Heavy, this is not an objection that would rule out this kind of mission architecture.
Only the high costs associated with SLS would preclude this approach as unaffordable.
So far, the only real downside I see to this approach is the need to do LEO assembly of those landers. Their diameters are typically around 10 m, too large to put together on the ground and ride up. The real choice is (1) do we need an SLS to launch these landers (a minority of the tonnage to send)? or (2) do we learn how to provide the assembly bay and spacesuits necessary to do on-orbit assembly of this type?
We have about 5-10 more years before we need to freeze the design for the Mars mission for the 2030-2035 time frame. Which do you believe would be easier to do in 5-10 years: (1) get SLS flying, or (2) learn how to do assembly in space and develop a supple spacesuit?
GW
No you don't. We've been over that. With transponders on the surface the chances of failure to land in the correct place are as near zero as anyone could want.
You could equally argue that if you put the ascent vehicle with the descent vehicle you risk damage to both in a non-fatal accident, such that people could be left stranded without a functioning ascent vehicle (whereas with separate landings if there is some damage to the descent vehicle, you still have your ascent vehicle ready to go).
Then you have to worry about the landing vehicle with the people landing in the wrong place, though if the ascent vehicle for the next mission is coming along shortly, you could always direct it to the lander.
You could, but that may create a 1 in 1000 chance of "loss of mission" (i.e., something lands too far away and everyone dies).
Not if you land it first. The descent vehicle only follows if you have established the ascender has landed safely and in good condition.
Bigger than Red Dragon. Musk will want to land a capsule of humans on Mars with a system for launching it back to orbit, I suspect. So it'll need maybe a 25-tonne launch stage (2 tonnes of structure, plus either a tonne or two of hydrogen or 5 tonnes of methane). It'll also need maybe 10 tones of consumables and solar panels, for safety.
Why couldn't you land the ascent vehicle separately?
My suggestion for powering a Rover would be a solar array suspended above the roof of the vehicle (maybe 4x4 metres and a solar array "train" (about 10 metres by 6) that would be dragged behind the vehicle, together with solar panel cladding on the sides of the vehicle. . There would of course be ultra-lightweight solar panels. For the train I would suggest the PV panelling be set on a very lightweight framework of nylon rods or some other light material. Where the rods intersect there could be fixed hardy inflated plastic balls that would allow the train to bob over the rock strewn ground. This should avoid problems with snagging.
All those solar arrays should generate about 15 Kws average through the core daylight hours which should be enough to power the vehicle.
On board would be a 30 KwH battery. When the vehicle doesn't need the direct power from the solar arrays, they would replenish the battery.
Returning to your question about powering the rover, Bob, I have a different suggestion. I doubt you could do very much with a vehicle powered by 4 kw (or 6 kw without running life support). It would be slow, and that would be risky if you go out several hundred kilometers and someone has a medical emergency. It would also be very underpowered if you wanted to run a crane or push rocks or fill a trailer with dirt.
So I suggest you leave the reactors at base, where their radiation can be mitigated with dirt shielding anyway (I'm not sure you want two reactors on board your rover; what's the radiation risk, anyway?). I'd haul several hundred kilograms of liquid methane and oxygen along instead, which could even provide some shielding against cosmic radiation if they were on the roof. I'd run them through a small internal combustion engine (basically, a natural gas electric generator like the kind you can buy for your house or a small business) and power your six wheels with six independent electric motors. I don't know the mass, but it should be easy to look up natural gas electric generators. it's a well developed technology. Let us say we had two 30-kilowatt electric generators, one for normal use, one for backup if the first failed, and both for unusual situations (fast dashes back to base, powering a crane or a bulldozer, etc.). I bet they'd mass somewhere around 30 kg each. If methane-oxygen fuel cells were available--they're being developed--they'd be even better, because of their higher efficiency.
Other advantages of this arrangement: you'd have plenty of oxygen and water for the crew (you'd capture the water from the engine exhaust). If you brought along 100 kg/50 square meters of solar panels, you'd be able to power your life support system in an emergency. Double that mass (200 kg/100 square meters) and you'd produce 100 kilowatt-hours of power every day. If you had a small sabatier reactor and electrolysis system on board, you could manufacture methane and oxygen from Martian CO2 and stored water and that would allow limited, slow movement if you ran out of methane and oxygen (100 kw-hrs of batteries would do the same thing).
Back at the base, the reactors would continually put out power that could be used to make methane and oxygen, which would be stored up for the next expedition.
P.S.: You noted in your posting that 42 square meters of solar panels would put out 6 kilowatts of power, but that's when the sun is overhead. Since the relationship between the circumference of a sphere and its diameter is diameter times pi, that means a stationary (unsteerable) solar panel would put out about a third that much per square meter over a 24-hour period (almost 2 continuous kw). It's easier to think in terms of kilowatt-hours. 42 square meters would put out about 46 kilowatt-hours of power per day (in orbit facing the sun it'd produce 144 kilowatt-hours; divide that by pi). If 42 square meters masses 84 kg (roughly) and produces 46 kwhr (let's round it down to 42 kwhr to keep things even), than means you are getting roughly 1 kwhr per square meter and per 2 kg of solar panels. This is useful because Zubrin wanted a 100 kge (2400 kwhr) reactor. With solar panels, you'd need 2400 square meters and 4,800 kg of panels. That's about the mass of the reactor he was proposing (which was larger than necessary) . Of course, in dust storm season you'd get about 1/6 as much power, I think. But this gives us a good idea of the capacity of solar energy to power a Mars base.
I agree Rob - I think the MCT may be a few phases down the line...you're not going to immediately land 100 colonists at a location without highly developed ISRU facilities are you? And there would be little pointing in using the huge MCT to take a small team. So I think something like the Red Dragon is much more likely to be the first phase.
The Youtube video offers useful numbers and facts that are hard to find. But I am not as confident as he is. Space X has backtracked about the size of the Raptor engine, for example. Space X does not yet have a Mars plan; they are searching for one and have ideas, but not a plan. There is also the question of phase 1, phase 2, etc.; it may be that Musk wants to send 100 colonists at a time in a vehicle of the size the video suggests, but that may prove to be phase 3 or phase 4. If phase 1 is more of the sort of scale that NASA would imagine (and therefore could support) we may be talking about something with 4-6 crew launched by 3 Falcon Heavies or 2 upgraded Heavies, closer to the size of Mars Direct. It makes sense to start with something of that scale; one could get government support for it and one could start with a small crew who would scout out outpost sites, scout for water, etc. Besides, it is easier to start with smaller scale technology demonstrators, and cheaper to start with rockets for which there is existing demand. No one in the world wants a launcher than can put 1,000 tonnes into LEO, and the cost of developing it would be immense even for Space X. So it seems to me they must be thinking incrementally. That is also what they did with Falcon 1, 5, 9, and Heavy.
Interesting speculation on Space X plans for a Mars Mission:
Given we have been successfully operating solar powered vehicles on the surface, way beyond expected lifetime, I would suggest that we run with that. Electric motors are very simple.
I was just doing some further research. The guys who designed the SAFE-400 nuclear reactor, designed a smaller one: HOMER-15. It has 15 kWt producing 3 kWe, with reactor system mass 214kg. The rover would require 2 of these, or one twice the size. In the discussion "Light weight nuclear reactor, updating Mars Direct", I quoted figures for ISS life support. For 4 astronauts that worked out to 1.8 kW. I found a website selling an electric light truck that consumes 8 kW normal, 15 kW max. And a Chinese electric light garbage truck, motor rated for 6.3 kW. That's for Earth. Could a pressurized rover the size of a minivan, operating in Mars 38% gravity, trundle along at 50 km/h (30 mph) on 4.2 kW electricity, plus 1.8 kW for life support?
Curiosity rover may be much bigger than Spirit or Opportunity, but Curiosity's nuclear power system generates 125 watts beginning of life, 100 watts end of life. This vehicle would have 6 kW. That's 60 times as much power.
I like the sound of all that, Robert. However, the ascent vehicle could use methane manufactured on Mars.
I would go with a double mission - two crews of three. They could probably allgo on one ITV.
Pre-land the Mars Ascent Vehicle. The MAV would use ISPP, and carry astronauts and samples to Mars orbit. The MAV is inspired by Mars Direct and Semi-Direct.
Pre-land a laboratory with pressurized rover. The rover would have recycling life support, allowing for extended excursions from base.The crew would ride in the Interplanetary Transit Vehicle: ITV. The ITV would be assembled in LEO, using ISS as construction shack. Add TMI propulsion stage, add the lander. This whole assembly would travel to Mars as one unit. Aerocapture into high Mars orbit. Then crew would descend in the lander. Yes, the lander would be habitat, with recycling life support.
For return, the MAV would act as the TEI stage. This allows for ISPP for the entire return to Earth. The ITV would aerocapture in to Earth orbit, then aerobrake down to LEO, rendezvous with ISS and dock. The ITV would use a single Dragon as escape pod, in case aerocapture fails. If not used, it would stay attached for the next mission. Since the ITV will dock with ISS, any vehicle capable of returning crew from ISS can be used. If Dragon is to be used, then the "escape pod" may as well be used for crew return. In this case the second crew would ride Dragon up to ISS, then dock that Dragon to the ITV as their escape for return.
A couple additional backup modes. Notice the ITV has food and life support for transit from Earth to Mars, and back. The lander/hab has food for the surface stay. But the lander will be attached during capture into Mars orbit. This means if a free return to Earth is necessary, all that food will be available for the trip. And life support in the lander/hab would be available as backup for the ITV.
Mars Direct has life support on the hab/lander, and ERV. My plan has life support on the hab/lander, ITV, and rover. So the rover is an additional layer of backup. Is that too much? Could recycling life support be designed more compact than currently on ISS? Compact enough for a minivan-size rover?
I propose 4 crew.
The Mars Rover expeditions have shown there are many places on Mars where there are large plains scattered with rocks of manageable size.
The pre-landings could serve several purposes:
1. Laying guidance transponders.
2. Clearing a safe landing zone.
3. Manufacturing rocket fuel for an ascent vehicle (or maybe on a first mission, storing such fuel).
4. Providing long term consumables for a two year stay.
5. Providing mining robots to mine for water, iron ore or other resources.
6. Establishing a surface hab for the first colonists to transfer into.
7. Providing an automated farm hab to grow food on the surface.
8. Mapping of the surface - down to 10s of cms.
Louis,
I've never thought that landing accuracy was a particularly challenging aspect of the mission. JPL is trying to call a snow day on manned Mars landings due to their aerocapture entry accuracy, which is still less than 10km. No manned mission needs to use aerocapture. Any manned EDL should start in LMO.
Until your explanation of what you wanted to do, I thought you'd suggested littering the landing area with supplies to ensure that the astronauts would have consumables once they'd landed. We already have high precision surface maps. We need to test a transponder system or GPS that permits two or more vehicles to rendezvous on the surface.
If you want to set up a base of operations as soon as you get there, then you can have the robot or robots start deploying structures for a base. Understand that as soon as you establish a base, you're never going very far from that base.
Pushing rocks and debris out of the landing area is an excellent idea but that could take a long time, if it's even possible, without real earth moving equipment.
Rendezvous is something NASA has down. Apollo 12 landed close enough to Surveyor 3 that astronauts walked over, removed some parts, and returned them back to Earth. Those parts were studied to see what long term exposure to the lunar environment did to them. If Apollo could do that with 1969 technology, then how reliable is modern technology?
When I talked to Robert Zubrin about Mars orbit rendezvous, he didn't like it. He thought it was risky. Especially a mission plan that requires both surface rendezvous (landing close to something pre-landed) and orbit rendezvous. But Dragon and Cygnus do it all the time, completely automated/unmanned. And Russia did it with Progress, Europe with ATV, Japan with HTV. And NASA completed several manned rendezvous/docking: Apollo 11-17 (13 docked but didn't rendezvous), Apollo 10 (LM didn't land but did everything else), Apollo 9 docked in LEO. Gemini VI-A rendezvous with Gemini VII in December 1965. And all those Shuttle flights to Mir and ISS. I think orbit rendezvous and docking is mature now.
I agree Robert. If we have GPS, and can have cars that park themselves, cars that drive themselves, I simply don't believe we can't have accurate rendezvous and docking in a Mars Mission context.
I wasn't arguing Red Dragon could be reused.
Why on Earth do you think we would be incapable of landing accurately in the desired zone if we have transponders on the surface? How many aircraft completely miss airports? Landing with retro rockets has none of the difficulty associated with landing a plane on a runway. It has its own challenges - but remember all the Apollo landings (and ascents) were successful - and they took place nearly 50 years ago!
It's not a question of "scattering" supplies. Once the first robot is down and has laid transponders, all the landings will be accurate. Remember we have cheap cars on Earth that can park themselves. No reason why in a multi-billion dollar project we can't get robot landers into the desired zone. A robot tow vehicle can ensure that all the supplies are towed accurately to collection point which will be within 150 metres of the lander zone.
I'd get a mapping robot down there first so it can map the whole area, lay transponders and paint marker stones white. The map data can then be sent back to Earth and used to aid guidance of the pre-landers.
The mapping robot would probably be something like a one tonne robot vehicle with capability for: laying equipment (e.g. transponders and PV panels; pushing rocks and small boulders out of the way; and maybe digging.
Louis,
Reusing Red Dragon for subsequent landings is not possible. It's wishful thinking. No spacecraft ever built has been reused after reentry. The months of refurbishment work to re-certify the orbiters for flight after each reentry in enormous specialized terrestrial facilities that employ hundreds of workers doesn't count.
You either land a really small and light one man capsule for a human or you land as big a cargo package as your lift vehicle and EDL solution allow with a single launch. That'd be between 15t and 17t for F9H if you use SEP to send the payload to Mars. The key to survival on the Martian surface is mobility and complete redundancy. If you land far off course in Red Dragon or any other EDL solution that does not include a fully fueled ascent vehicle and you're not mobile, you'll probably be a permanent resident. If you design a mobile mission architecture that's required for any real surface exploration effort, a side benefit is that you can screw up landings something fierce and live to tell the tale. You still have to land within a hundred kilometers or so of a waiting surface rover, but landing 20km away from a habitat module doesn't equate to loss of crew and loss of mission.
Put another way, what typically happens here on Earth when you miss the runway? The same thing will happen on Mars. Some things you just have to get right. EDL on Mars is just one of those things.
Littering the landing area with supplies won't help, either. You can't throw supplies all over the landing area and hope you land near them unless money is not a problem. If money is not a problem, you can afford to land the most massive multi-person lander your heart desires, complete with a fully fueled ascent vehicle and habitat module. Money is a major problem. That's why scattering extremely expensive payloads all over the Martian surface isn't an option and neither is designing massive EDL vehicles.
The reusable rocket will certainly reduce the costs of the Mars Mission but I was referring to the "Red Dragon" proposal for a lander:
http://www.space.com/24984-spacex-mars- … ragon.html
I have not had the chance to run the numbers but this is what Loius is refering to:
louis wrote:Entry is not a problem - it is clear to me that the Space X cantilevered design will work. We just need a minimal descent/ascent vehicle. Once people get to the surface they can then transfer within 3 days to a full functioning hab that has been pre-landed.
kbd512 wrote:I agree with need to have minimalist descent/ascent solutions for humans, but what does the SpaceX "cantilevered design" have to do with that?
http://en.wikipedia.org/wiki/SpaceX_reu … nt_program
The reusable launch system technology is under development for the first stages of the Falcon family of rockets. It is particularly well-suited to the Falcon Heavy where the two outer cores separate from the rocket earlier in the flight, and are therefore moving more slowly at stage separation. If the technology is used on a reusable Falcon 9 rocket, the first-stage separation would occur at a velocity of approximately 2.0 km/s (6,500 km/h; 4,100 mph; Mach 6) rather than the 3.4 km/s (11,000 km/h; 7,000 mph; Mach 10) for an expendable Falcon 9, to provide the residual fuel necessary for the deceleration and turnaround maneuver and the controlled descent and landing. The reusable technology will also be extended to both the first and upper stages of the future launch vehicle for the Mars Colonial Transporter.
http://upload.wikimedia.org/wikipedia/c … raphic.jpg
If you label launch after refueling on Mars and look at booster burn back as the descent to Mars we have what would be a powered landing with no parachutes or heat shield as a developing method of how to solve the mars landing.
Finally found the altitude of seperation....
http://www.technologyreview.com/news/52 … -to-earth/
A camera on the second stage of the rocket captured live video of the nine SpaceX-built Merlin engines firing on the first stage of the rocket, with the plume of flame and smoke gradually expanding as the air around the vehicle thinned. At about 50 miles in altitude, and traveling at about 10 times the speed of sound some 35 miles off the Florida coast, the first-stage engines cut off as planned. As the first stage dropped away, the single Merlin engine in the second stage fired to propel the Dragon craft the rest of the way into orbit. Another camera view showed the Dragon moving away from the second stage into space with the Earth as a backdrop.
