New Mars Forums

You might think it would be easier to get volitiles from Venus then asteriods, but you would be dead wrong.  Venus has a gravity well nearly as dense as that of Earth, so if you were to stop there and pick up gasses you would have to fight that gravity on your way out.  And on top of this Venus has got to be one of the most inhospitable locations in our solar system.  It is closer to the sun increasing worries about radiation (both thermal and ionizing) and the planet itself is a veritable hell hole.

IMO the ideal location to get volitiles for the moon (if you want to go forward with this crazy plan) is right here on Earth.  Our atmosphere and ocean has pleanty and a sufficently long elevator cable should be able to hurl them at the moon with little difficulty.

I've heard of Karov's idea before but heard of generating electricity from it, a great improvment.  But also, once your pipe passes the LaGrange point you can also use it's velocity to add to your Delta-V, properly timed this system could at least augment the transportation of nitrogen to mars.  At best no manufactured items would be needed at all.  Freeze a ball of nitrogen then give it an insulating coating water ice, then wait for the proper time and hurl it on it's way.  Of course the timing would have to be of nearly impossible precision and direct windows would probably be rare if they existed at all, and your cable would have to be very long, but hey every little bit helps right?

I don't think you are properly taking the moons low gravity into account.  Since it's gravity is only .16 G that 10MT mirror would only weigh about 1.6MT on the Moon, so the structure to support could be fairly lightweight.  While it mass remains the same, which is important when you consider rotating moving/rotating it, this movment will occur very slowly, so the necessary motors would not have to be very power/large.  In fact, haveing someone go out every 8 hours or so and manualy adjust the grid might be plausible.  And of course, as the mirror mass decreases so will the mass of the necessary support equipment.  All you are realy looking at is a hinge and a perhaps a small motor anyways, the mirrors are strong enough to support themselves in Earth gravity.

As for the problem of tracking the sun 360* around the sky, this is actualy a fairly simple problem.  If for some reason it's not practical to have the primary track the sun and focus on your furnace (and I don't see why this would have to be the case, the geometry is certianly possible), you would just utilise a secoundary mirror to reflect the concentrated light onto the furnace.  Such an arangment may be used in any case to alow the light to be concentrated more easily.

Now I do not think that nuclear reactors are OVERLY hazerdous, just that they are much more so than a solar dynamic system.  One would not want to approach one of these space reactors to closely or linger nearby for to long as the will likely not have enough shielding.  This creates a delima however as the furnace has to be fairly close for efficent heat transfer AND you are going to want to visit the processor to get your oxygen out of it.  This has made me worry a little bit about Mar ISPP as well.

I'm unclear on this argument.  The furnace as you say will be realtivly cheap and simple.  The nuclear reactor however is neither.  It's hard for me to imagine a situation where the reactor would be cheaper per thermal watt than a mirror would be.  While the solar furnace would certianly have to be bigger, it is likely only to be a fraction of the weight of any generation system in anycase.

This brings in another point.  The solar system could be utilised practicly forever with proper maintence.  The nuclear system is going to have a definet shelf life, after which it would be useless.  The system would have to be abandond or disassembled as the old reactor would remain a danger for years to come, with disposal in place being the most practical retirment option.

Not necessarily so.  The SP-100 would get about 400W/kg of thermal energy.  The 1kg/m^2 mirrors would get 1400W/kg of thermal juice, MUCH better.  And as you scale up the amount of thermal (basicly total) energy produced with a nuclear reactor you also scale up the radiation dangers and possible scale back its effective lifetime.

I hate to sound rude about all this, but some of this information is easily avaliable on the internet if you just take 3 secs. to look for it.

A quick search on google gave me results on my http://www.google.com/search?q=mars+sol … cial]first page. 

The exact amount of solar radiation will very of course depending upon exactly how, when, and where you measure it, but for Mars a good value seems to be around 500 w/m^2.  Roughly half that of earth.

The question about nuclear weapons is more complicated (you find your answer in 3 secounds with google), but still a good excersies for a high school student.  Figure out the amount of energy your bomb is going to release, figure out the amount of energy necessary to convert CO2 ice into a gas, then simple algerbra will give your solution.  And there you go, a rough "back of the envelope" solution.

In any case I agree with what most of the others have said here.  A single nuclear weapon is going to be just a drop in a very large bucket here.  You would have to employ them in mass to get any kind of real effect.  It's important to rember that mars is infact REALY big, and the effect of any single weapon is realtivly small.

I think some of the concurns here are overblown however.  A single nuke isn't going to throw out enough dust to seriously effect the amount of solar energy the planet recives.  Especialy if it was detonate over the poles as you propose.  I doubt one could even effect the global temperature and pressure in a measurable way at all.  I will grant that dust loft and airtime are unknown for mars and probably much greater than that of earth, so if you did deploy alot of surface nukes... who knows.

Likewsie you are correct that the overal concurns about radiations are mild in comparision to the general hostility of the planet.  You wouldn't want to stand at ground zero of course, but once it was over the horizon you would be fine.  Fallout is also less of a concurn if you have to live in a enclosed life support system at least the 15 years or so it would be any kind of concurn.  But again, if you were to start droping surface nukes on the kind of scale you would need to, well it might be another story.

In KSR mars trio, she talks about drilling deep wholes and setting of nukes in them to help melt the permafrost, this sound like to me like a much better idea to me, but even here it would have to be deployed on a very large scale to achive anything.

If I am being simple minded here, it's because the problem truely is not that complex.  We won't have any war in space for the same reason the Russians never invaded West Germany.  Such a conflict would quickly escalate to more widespread warfare, eventualy culminating with nuclear weapons and widspread destruction on both sides.  If China (for example) decides to shoot down one of Frances space assets (landing craft or whatever), France isn't simply going to shrug their shoulders and ignore it, they would strike back at any Chinese targets they could reach in retaliation.  The Chinese then strike back, and on and on it goes untill there is nothing left of France and China.

The thing is that both China and France know this is the likely outcome of events, and so don't do it.  The risk of nuclear war is not worth the marginal gain of a monopoly in space.  This kind of Brinkmanship is certianly scarry, but it is what has prevented nuclear war for some 50 years now, and will on into the future.

No, MAD (Mutualy Assured Destruction) as a policy works on all fronts.  As I pointed out before, France isn't going to treat an attack on one of it's space colonies any diffrently then it would an attack on one of it's colonies still here on Earth (I think they still have a couple), or an attack on it's homeland itself.  For quite some time the US and NATO were hoplessly outmatched in Europe, but with the bomb to back them up, the Russians never invaded because of the danger of escalating to a nuclear war which would mean MAD, where nobody wins.

Man and I though "Star Wars" and the SSI (Strategic Space Inative) was a form of stupidity that Regan had only inflicted the US with.  Such a system is impractical and extreamly expensive here on Earth.  Building one all the way out on Mars is even MORE impractical and would be so hidoulsy expensensive as to be completely impossible.

Currently our "space command" sits back at Cheyenne mountain keeping an eye out for a nuclear attack which hopefully will never come.  If one does, there only response is to launch a retalitory strike of there own.  Thats it.  The US doesn't have any means of enforcing anykind of stragic control of space.  Indeed, the Russians were the last ones with ANY kind of space arsenal, all of which have left service a long time ago, and probably wouldn't have worked that well in the first place.

I'm all for a joint effort. I'm just saying we should follow the "golden rule" he who pays the gold, makes the rules.  I wouldn't be very happy if the US had to put up all the dough for a mission, but someone else got to call the shots.

This point (if in fact we ever do reach it), is a long ways off.  Developement of Mars or anyother extra-terrestial body is going to take 50+ years, no matter what.  For some of the stuff you talk about (meaningfull colonies, Space defense platforms considerbly longer than that).

What!?! When a nuclear bomb explodes intense radiation is emmited in all directions.  The bomb caseing (if it somehow survived the conventional explosions that triggered the bomb), would most certianly be vaporised in the blast.  The amount and kind of radiation (which is ALOT and mainly thermal) does not change wherever a bomb is exploded.  Actualy heat (being the increased motion of atoms) is not actualy produced by the reaction (only EM and neutron radiation is), but is rather a result of the intense radiation coming into contact with some matter.  The casing (beign at ground zero) is going to absourb alot).  Without air to absourb the radiation, the effects would propigated inverse square law, and damage could probably be expected at great distances.  Heck, even if the casing somehow did survive, so much radiation is released in the visible spectrum, you could probably see it THROUGH the casing.

I have to disagree with Martin_Tristar here, your line of reasoning simply doesn't make sense.  For at least the next 50 years, and quite possibly for much longer than that, Mars is going to be of no more strategic resource than Antartica, and substantialy harder to get to at that.  Honestly, the planet is millions of miles away and has as much surface area as Earth.  It is of little importance if the US, UN, Russia, China, France, Japan, or any other country "claims" it as there own.  It's not like they will able to enforce a claim on the entire planet or that Mars is going to run out of room anytime soon.

What RobS says makes more sense.  He who pays the bills will make the major decisions with the locals having a great deal of autonomy.  Making it a bone of geo-poltical contention simply doesn't make sense.  It's not a strategic military outpost by anymeans, and it won't be of signifigant economic utility for a long time to come.  Certianly much great science will come from it, but that has always been freely shared.

As for the theory of the US (or some other Mars coloniser) using there "critical" mass to hinder other groups from developing mars, this is absurd.  As I pointed out before Mar's distance makes developing that so called "critical mass" a event that will happen in the distant future.  And even then, the shear vastness of space and mars makes any attempt to monopolise it's resources futile.  What are they going to do, shoot down the landing crafts?  Invade your colony with tanks and inflantry?  Impractical if not clearly impossible.  And clearly any nation that can send a mission to mars can also develope nuclear weapons and delivery systems along with the MAD deterent that implies to hostile options.

I think Mark Friedenbach had a great point, Exhaustion is a very major danger.  Rember that the the astronauts are probably going to be on a 100% oxygen atmosphere during EVAs at a lower air-pressure then is typical her on Earth.  They and very dependant upon the suit to remove CO2, provide oxygen, and remove excess heat.  Even though mars is very cold, it's thin atmosphere is probably a very good insulator.  There have been several near disasters during EVA for just this reason.

I would also point out that even with the lessend gravity a body in motion still has inertia, which is likely to be even greater on Mars, due to the additional mass of the spacesuit.  In the event of an accident, even if the suit does not rip, their is still the dager of broken bones, and other damage to possible delicate spacesuit equipment, like the LSS and comunication systems.

I don't think Orion drive are totaly useless for space travel, but the range of its application will certianly be limited.

First off, neither is going to be lifting people off of the planet.  Railguns cannot practicaly do it.  And while Orion might be able to, one must be realistic, the enviromentalist are never going to let it happen, end of story.  I also tend to agree with GCN's assement that it would be economicaly impractical.

Even travel within our system is difficult.  Orions push plate and shock absorption system are very massive and so assembly of such a vehicle is fairly difficult.  Also if launching from Earth oribt, there may be EMP effects to consider as well.  But for voyages to the outer system, it does have it's advantagtes, high thrust, high specific impulse, and a realitivly simple system.

But where an orion type system realy comes into it's own IMO is in moving asteriods.  I'm not 100% convinced that moving the entire asteriod is more practical than just moving the end product.  But if that is what you want to do then an orion type system is definelty the way to do it.  Big NTR, Railguns, Ion Drives, ect are all far more complex and massive then an orion type system, and offer little advantage in terms of thrust and ISP.  Indeed, you may be able to do without a pusher plate and shock absorption system at all using the asteriod itself for that role.  In that case all you would have to deliver would be a well protected system for delivering the nuclear weapons.  Perhaps you land a well armoured shack on one end of the asteriod and deploy the nuclear weapons via a small rocket/probe.  In any case the system would be simple and effective.

But for interstellar travel I think Orion will probably be quite useless, it simply does not deliver enough ISP.  And the number of nuclear weapons you would have to build would very large, there may not be enough nuclear material.

No, no, none of this is sufficent testing.  You must test things in the way you intend to use them, or there realy isn't much point to it.  If you are going to use your spacesuits, for example, hundreads of times with minimial time for servicing and repair then that is how you should test them, not with hoses replacing their life support packs.  Or if you are going to use your Rovers for multiple hundread  km then this how you should test it, not just drive it around with a crane.  If you are not simulating the enviroment in which an accident might occur, what is the point?

The other point is that to realy have effective testing you have to test all your systems in concert.  A failure in one system may not lead to disaster but it may cause another system to fail in unexpected ways.  You also have to develop systems for dealing with accidents when they do happen, and the place to do this is not on Mars.

And again, its not as if there is nothing to do on the moon.  There are lots of things we still have to learn about the planet.  And this knowledge will be usefull in our later exploration/development of the solar system/universe.  There are several other large stoney planetoids in the solar system, but the moon is a heck of a lot easier to access.

I know there are terrestrial reactors which use liquid metal (usually sodium) yet have good-excelent effeciency.  But they require a secoundary cooling loop, which adds to the mass of the system.

While I agree that a bigger booster is probably the solution, I don't see "orbit assembly" as you call it as realy being a showstoper.  This isn't realy orbital assembly, it's just orbital docking, something the US and the Russians have LOTS of experience doing, dating all the way back to the Geminin missions.

I don't disagree with this, but I think there are some important parts you have left out the equation, namely development, infastructure, and transportantion costs.  Currently no one uses the carbonly process to refine platnium, much less doing it in an exterrestial enviroment (be it mars/moon/asteriod), so you would have to pay the costs to develope the equipment as well.  Likewise, you have to develope tools and techniques for minning this stuff in an exterrestial enviroment.  This will probably prove to be quite difficult, as all terrestial methods are either labor intensive (shaft minning) or requires very large quantities of explosives and equipment (pit minning) and both may prove hard to impossible to use off of earth.

Earth also has the advantage of a developed infastructure to rely upon.  A terrestial mining company doesn't have to pay the for the powerplants, roads, water facilties, ect... it needs to use, those resources are already developed here on earth.  An off planet facility has to pay for all those and more, including housing and lifesupport for it's workers.  And the company will probably have to develope some sort of system for delivering the metal back to Earth as well.

But most importantly of all, is the cost to transport all this equipment to your destination.  Minning equipment is heavy, as is the equipment to refine it.  Launch costs being what they are, and given the small fraction of that payload that is actualy deliverable to your destination, I think the cost for transporting you machinery may quickly overwelm the cost of the machinery itself.

Given all these factors, I don't think investment costs in the trillions of dollars is out of line.