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Although I think that the near-term changes from biotech and nanotech are highly overrated, the 100-year time scale for the two technologies could easily get a vacuum-proof person. I'm sure that turn of the century vacuum tube manufacturers had all sort of unrealiztic claims for how their products would revolutionize society. I'm pretty sure that no-one though that in 100 years, there would be an Internet that carries most of the world's commerce and information. We tend to overestimate short term technological change and underestimate long term change.
Even if the changes for such an individual were severe, you'd get thousands of people willing to go that route - look at all the wierd and bizzare things that people do now. There's amurder tial in Germany recently where a guy's on trial because he ate another man - with that man's INFORMED CONSENT. The guy he ate WANTED to be killed and eaten - they even videotaped the whole thing for proof. There's even the equivalent of a cannibal/meal dating service out there although tis appears to have been the only casualty so far.
No, you're not going to hurt for volunteers. Furthermore, those people will have kids and you'll soon have an adapted spacefaring race. O'Neill colonies are probably the future of humans in space. Vacuum adapted folk make even more sense in that framework - no atmosphere and life support to worry about.
What you're basically talking about is an M2P2 type solar shade. There's some advantages and disadcantages to this approach.
advantages: much cheaper to make and easier to maintain. If one unit goes down, you can just fire up a quick replacement backup.
disadvantages: solar sail effect - if you are making the dust particles absorbtive/reflective, you are still getting giganewtons of thrust. With such a low - almost 0 - sail mass, it's going to be impossible to keep your sails in place. There's a reason that M2P2 is a hot topic in spaceship drives right now. i did rough calculations that showed that if you fired up a 100 kg craft in Mercury orbit with a ~90 km diameter M2P2 sail and a reflectivity of 1%, the spacecract would hit something like 0.1% of the speed of light in about 5 days as it blasted out of the solar system.
Problem 2: keeping the dust particles in the sail field. The sail field has a very weak effect upon the dust particles and at 15kW/m^2, it's going to require a VERY powerful field to keep your dust particles from just flying away.
Problem 3: most dusty M2P2 models figure on a 1% albedo, TOPS. Even that's not terribly plausible, a 1% reflectivity is pushing the limits.
Since we've got to bring the light level down to about 10% of the initial amount, you'd need 229 seperate layers of dusty plasma shields to get the light level down that far. Also, you're then throwing away Mercury's most valuable resource - solar power. There's no good way to harvest power from a dusty plasma sail that anyone's figured out yet.
The only way to attenuate the light with light materials would be a non-dusty M2P2 sail that stops the solar wind, catching a few hundred meganewtons of force and then a series of thin film solar collectors that progressively attenuate the light an collect power. Still, the engineering and maintainance of such a structure would far, far exceed the gross world product of the Earth today.
There's no good reason to try and terraform something like Mercury, just go below the surface and weather out the temperatures there. What you want to do is like paving the entire surface of the Earth (a much easier task, BTW) so that standard cars can go everywhere instead of making off-road vehicles and planes.
The proximity of asteroid belt resources to mine platinum group metals is also potentially lucrative. Those metals are one of teh few things that would actually be economical to ship across the solar system. Platinum is presently $30,000/kg. The delta V to get from the asteroids to Mars LMO is about 2.7 km/s and from there, a 0-energy trajectory to LEO is prety much free. A total delta V of about 3 km/s requires relatively little money to accomplish. The demand for platunim group metals is nearly limitless. Many thigns like pollution reduction, hydrogen storage cells and other technologies are basically stymied by a low availability of these metals. A Mars base, properly equipped, could actually start paying for it's own development.
The problem is that Mars Direct is already very mass-low. You're really pushing the low end of safe with that plan. If anything, you should increase the lander mass.
What would probably be better would be a large, very capable RV in addition to the crew hab. The RV might have a 2000 km range and be capable of sustaining a crew of 3-4 almost indefinately. (RTG/nuclear/solar power) You could then make month-long extented journeys across the planet and still get back to the base.
A CH4/O2 powered ballistic hopper would also fill in quite nicely for this duty. You can just jet to an area of interest, grab some samples, camp our for a few days and then blast back to base for detailed sample analysis and refuel.
ERRORIST - it's responses like the last one that make talking to you such a complete waste of time. Relativity and time dialation effects are well known and measured. If they didn't happen, GPS wouldn't work properly, gold would look like silver, mercury would be a solid at room temperature, Mercury's orbit wouldn't precess and gravitational lenses wouldn't occur.
If you want to keep sticking your head in the sand and ignore vast quantities of scientific evidence because you can make some asinine analogy using baseballs, I think we'd all appreciate it if you did it on your own time and would quit wasting ours. If you are just too damn lazy to spend an hour reading any number of well-written explanations of relativity or quantum physics you can find on the Internet through Google or to buy a $3 used book and read it, don't expect us to waste our time debating with you.
Newtownian physics is WRONG. It was proven to be wrong a hundred years ago. Even if parts of Einstein's relativity and quantum physics are proven wrong, the effects like time and space dialation, relativistic momentum corrections, wave-particle dualities and quantum uncertainty have been proven beyond a doubt. Comparing a baseball to a photon is like believing in a flat Earth or epicycles. If you don't want to believe in modern physics, feel free but please quit spamming the boards with it.
IF you could go at the speed of light, the answer is unknown. The math involved simply doesn't support such a question.
If you were going almost the speed of light, and switched on headlights, you would see the photons going away at the speed of light. An observer watching you would see the photons going just a tiny bit faster than you, slowly pulling away. The rason for this discrepancy is that your are now time-dialated - time slows down for you. Therfore, light seems to be leaving you at teh same speed. This is how special relativity works - light always goes at the speed of lihgt, no matter what frame of reference you're in because time and space warp themselves to compensate. More accurately, you are cutting through spacetime at a different 'angle' but that's a hard concept to visualize.
ERRORIST - what you are forgetting is that the light is already the most efficient drive mechanism available. You don't gain anything by heating the material with the laser. Any energy that goes into accelerating ions is subtracted from the beam - you can't get something for nothing.
Also, don't forget that lasers are very inefficient - you'd be better off just heating your fuel up with an electric heater.
What your'e proposing is the basic idea behind present ion engines except that it's a lot less efficient.
I know that the Falcon V isn't big enough for any reasonable CEV. However, Space X is talking about an HLV at some point in the future.
One point about the Delta rockets is that Sea Launch - a Boeing subsidiary - is already putting Delta out of business. My father works at an unlrelated area of Boeing and gets to hear inside scoop on lots of stuff. It turns out that Sea Launch was nearly killed by the Delta folks who realized that it would put them out of a job. the Sea Lunach Zenit launchers can loft mass for about 1/2 the price of a Delta. Fortunately, the Sea Launch folks seem to have made it through and there's a fairly brisk demand for those launches these days.
My guess is that the Space X folks can get slightly lower than Sea Launch for costs but that the final costs willend up being higher than they expect. Sea Launch is already fairly bare bones and frugal.
Compared to learning to fly a jet - a requirement for any spacecraft pilot, a bike should be trivial. Plus, you never forget how. I went for about 15 years without touching a bike when I was a teenager, sat on a bike a few years ago and just rode off like nothing. I'm pretty srue that you retain muscle memory for a bike longer than, say walking.
As for fines, I really can't see that as being a problem. Modern mountain bikes used sealed hubs that have a pretty high tolerance for particulate matter. The only spare parts you'd have to take would be things like chain links and wheel hubs. That would be a trivial amount of weight for numerous spare parts.
Incidentally, the Army has been investing in bikes heavily and a number of commando units are now bike equipped. In field tests, bike equipped soliders were able to go cross country to an objective, rescue 'hostages' and get them back to base before the foot-mounted team even got to the objective.
Cindy posted some great pics a while back showing dust devil tracks on the top of Olympus Mons where there isn't enough atmosphere to make a dust devil now. Meteoric dating puts those tracks at less than 3 million years old. I think that it's quite likely that Mars undergoes episodic warmings. If that's the case, if any life existed on Mars, it's almost certainly still there, hibernating or in hot springs.
These episodic warmings also raise hopes that Mars can be successfully terraformed - obviously, the polar caps and ground containenough sequestered gas to reconstitute quitea bit of atmosphere.
I think that the biggest objection is that there's no guarantee that you'll be able to go anywhere. Imagine putting wheels on a house (the hab will have to be at least that big) and dricing it around the countryside where there aren't any roads. You can go a few places but overall, you're going to constantly be stopped by impassible terrain features that a smaller rover can easily navigate. Plus, if you end up tipping your hab over or crashing it into something, you're kinda FUBARed. That said, I've seen that many of the modern hab designs have a small set of wheels for some level of mobility.
Mars is by far the easiest of the planets to terraform. Venus is probably the second most easy. However, it's probably 20 times harder.
Sun shades are something that an engineer can doodle on a piece of paper but just can't be practically built. A reflective shade to raise the temp of aMartian polar cap is one thing. A shade that's blocking a significant portion of the total solar energy hitting a planet is another entirely. See the Mercurt terraforming thread for how crazy solar shades end up getting. I suppose that a Venutian shade is less crazy than the Mercury one but it's still very impractical. For one thing, you're talking about a structure that's a significant fraction of the diameter of a planet, massing billions to trillions of tons. If anyone has any suggestions as to how to build one of these, I'm all ears. Furthermore, if anything fails, your ecosystem rapidly fries.
kippy - The He3 mining schemes I'v seen involve big balloons floating in the upper atmosphere of Jupiter. The problem is that if you stop there, climbing out of the gravity well is VERY difficult. I suppose if you use that He3 to power some sort of futuristic fusion drive, it's not to bad, but the amount of energy spent is gigantic.
chat - go back up and you'll see my musings on hitting Venus with large numbers of small ice chunks. For one thing, there aren't any ice asteroids in the asteroid belt, you have to go out to at least the Kupier belt by Pluto or further to find any. Also, unless you deliver all of the kinetic energy to the atmosphere alone, not much gets knocked off. Even a huge impact would leave the atmosphere relatively intact. Also, your 1000 km impactor would shatter the crust of Venus. It's nota matter of waiting a few centuries for the 'nuclear winter' to abate - it's a matter of millions of years waiting for the crust to reform from magma. If you calculate the sorts of energy required to give aplanet spin and to loft a moon, the energy levels are just ridiculous. We're talking about events that raise the average temperatuer of the planet by hundreds of degrees C. Also, the formation of that moon would take eons and in the meantime would result in large amounts of meteoric material raining down on MArs for extended periods of time - read millenia.
Mars Dog - If Venus rotated fast enough to send the atmosphere into geosynchronous orbit, the entire planet would blow up like a skeet shot by a shotgun. You're talking about rotating the planet fast enough to largely negate gravity.
The answer for the solar shade is 'very wild'. My calculations account for the light pressure. The solar wind is about 1/10,000th the force (still significant) but this is a highly damaging force. You're looking at a solar wind flux 9 times higher than here at earth. Your Mylar will quickly degrade under a constant stream of 500 km/s ions. The only way to get around this is to make the shield very thick and massive. That helps a bit since it allows the shade to keeps its shape and to weigh it down to counteract the light force.
At this point, you're looking at a shade massing at 1.9 trillion metric tons. (assuming 100 grams/square meter of mass - a fairly reasonable number) Furthemore, being inside the L1, you no longer have orbit stabilization - your shade will start to pull ahead of Mercury because of the smaller orbit. That's OK since you can just tack the shade to provide lateral thrust. However, the situation is VERY delicate, any perturbation in light levels, etc will result in a runaway shade. Furthermore, meteor impact and terrorist actions would be devastating to the shade.
What happens to your terraformed Mercury when 15 kW/m^2 suddenly hit it?
FOOMP!
15 kW/m^2 is about what you'd expect to see inside a toaster when its running.
Even IF you can build this crazy shade - which is doubtful - it's got to have a diameter > than Mercury's and be thick - and you can get an atmosphere there (which will have to be imported, if you can avoid catastrophic loss of the terrafoming from shade failure, even if you can impart a spin to Mercury - even if you can do all this....
You have a tiny, rather miseable planet.
Much better to just burrow underground or sit on that train track and mine metals and set up solar collectors than it is to try and terraform.
I should clarify - by easier to deal with hot than cold, I mean large extremes. It's much easier for humans to survive on a partially terraformed Titan at -70C than for them to survive on a partially terraformed Venus at 300C. When its cold, you can just put on a jacket, so to speak. Trying to deal with excess heat is very difficult.
I doubt that Titan will ever have liquid water on it and there would be no reason to try - it a big oil spill anyway. Trying to make the open surface of Titan livable would be like trying to remodel a living room in the gastanks of a gas station while they were still half full. My point is that getting worlds other than Mars to shirtsleeve temps with O2 is just not feasible. In any sort of timeframe that would be plausible for any non-Mars terraforming project (and arguably even Mars) we will have the biotech and nanotech to make our own bodies adapted to vastly more hostile environments. Along with more advanced engineering, it's just a waste of valuable energy to terraform most planets.
For example, it would probably be fairly straightforward using tech 100 years from now to modify humans to be vacuum compatible. Having colonists that are compatible with the environment rather than vice-versa makes much more sense.
The hopeful thing here, though is that this is a win/win situation. If the CH4 is from life - huzzah! If the CH4 is from geological activity - huzzah!
Geological activity would indicate that there are active hot springs which greatly increase the probability of life. Not to mention the availability of liquid water and geothermal power.
One thing to keep in mind is that 10 ppb of CH4 represents about 260 million kg of CH4. Whatever is making this CH4 is doing so in substantial quantities. It's also apparently geographically localized - again hinting at either a geologically active region or a life-rich region. And, of course, there's also the possibility of both - CH4 emitting volcanic vents with methanogens living in them.
Re: 0-energy trajectories:
I don't think so, based on what I've been able to understand in the papers. Lo talks about the manifolds that seem to be sperical shells that surround the sun with radii the same as each planet's orbit. These orbits can't pass through these shells except where the planet actually sits and givea 0-energy trajectory through. What puzzles me is that this means that an Earth -Mars mission just leaves here and heads to Mars. Obviously, you can't get an Earth gravity boost from a spacecraft that's still in its gravity well. Perhaps there's enough ofa gravity boost that one gets from swapping between the Earth's and the Moon's gravity wells sequentially but that strikes me as fishy.
Re: Hubble:
Well I'm glad that someone is thinking along these lines. However, this is a temporary solution. The Hubble's gyros are about to go belly up. I doubt that this tug has the fine pointing capacity to keep Hubble operational if the gyros fail. At least, it won't become a 'ballistically implanted reef' as the company so finely puts it. Also, there's no way to install the upgraded camers which have already been built.
I'd love to see some sort of actual tug that has a few robotic arms that can reproduce a human's movements reliably. I mean, most of our cars are built by robots, what's so hard about making a three-joint manipulator arm and putting in on a spacecraft for cryin' out loud.
That's a really cool idea - using the apogee kick motor as a docking point. Of course the eventual tugs will be orders of magnitude bigger but this sort of experience will be invaluable. (NASA should have made one of these things 10 years ago)
Now that O'Keefe is pushing to have Hubble be rescued by a robotic mission (WTF?!), it might provide some impetus to finally create a decent telerobotics presence in LEO. There's no reason to send astronauts to do work that someone can do from the ground.
That turbofan/rocket's a pretty spiffy idea. I also think that the scramjet is about as good as you can get for standard launch tech barring major advances in things like rotovators/space elevators/antigravity. Some further advances in scramjet tech can come from microwave power transmission that can further lighten the fuel load on the plane. Also, a maglev launcher system actually makes sense with a scramjet system.
However, I'm trying to head off the 'scramjets will make spaceflight too cheap to meter' crowd that always seem to crop on on places like Slashdot. I can realistically see scramjets getting orbital costs for things like fuel to LEO down to <$300/kg. However, that's still a substantial cost - lofting me and luggage to orbit would still cost more than my parents' house.
RobS - Again, I share your concerns. Of course, there isn't a free lunch here, just cheap ones. My biggest concern is, of course the process of getting to Mars L1 without having to spend all the energy fighting the Sun's gravitational field.
It's roughly analagous to a chemical reaction where you have two similar energy states seperated by a high energy activation barrier. This system seems to act as a catalyst that lowers that energy barrier, making it eaiser to get between the 2 equivalent energy states but I'm a bit unclear on HOW. I can easily understand how lunar L1 can easily feed to Earth L1 but Lunar L1 to MArs L1 just seems almost too good to be true.
I guess that I'm just relying on faith here - Dr. Lo has managed to successfully design a NASA mission that's almost finished and these 0-energy trajectories seem to be hot stuff these days. I assume that if they didn't work, someone would have raised an objection by now.
A qualitative analysis of the Genesis orbit seems to suggest that the L points basically let you hit any point in the solar system for nearly free. After all, after the inital orbital injection for Genesis was enough to send the probe to L1 and back to Earth.
Of course, getting to lunar L1 is expensive, I've maintained that all along. However, the advantage is that the equivalent to the OCS thrusters is enough for the rest of the mission. Even a simple refuelable chemical thrust tug could ferry stuff to L1 and then detach. The remaining engines on your cargo can be tiny along with smaller fuel tanks, etc. The overall weight savings will be substantial. All those heavy, expensive high delta V engines and tanks can go back to LEO for reuse. You therefore limit your high delta V mission requirements to the Earth-L1 corridor. I think that there will be significant infrastructural savings from this approach. Also, you can share booster tug elements with the faster crew and cargo missions. They can go to the lunar L1 with similar sorts of tugs (fast and slow) where they can depart on standard Hohmann trajectories.
(I am aware that the L1 requires a halo orbit for stability, I was leaving this out for succintness. I think that even L4 and 5 have a sort of halo orbit that forms from the Coriolis stabilization)
I'm not too concerned about Mars to Mars L1 since I don't anticipate large cargo loads going this way for the time being.
A scramjet isn't the end-all-be-all of spaceflight. It does help a lot, though. From what I've read, the Isp of a scramjet is close to 1000. While that's great, you have to deal with a fairly heavy scranjet not to mention the turbofans/ramjets that get you up to mach 4/5 where the scramjet takes over. Also, there's no guarantee that a scramjet can take you all the way to mach 25. If not, you've still got to have rocket engines. All of that eats up your LEO weight allowance so that you're lofting space jet rather than cargo. For example the Shuttle is a 100 ton to LEO booster that spends 80 tons of that lofting a kind of crappy space plane. A scramjet powered plane will do better but the same sort of problem is still inherent.
The scramjet will eventually change LEO boosters but it's probably going to be at least a decade or two and the difference will be evolutionary rather than revolutionary.
That's correct, the CH4 is definately out of chemical equilibrium. The question, as Cairan puts it is what the source is. Apparently (I've never heard this, but then, there's lots I don't know) the presence of CH4 in the Martian atmosphere has been something of a holy grail of Mars researchers looking for life.
However, this assumes that there is no residual geological activity on Mars. Geological activity (read: volcanic activity)and certain water-rock interactions can create CH4. Either that, or the Martians got a hold of a Case for Mars and started up a Sabatier reactor to make fuel for their invasion of earth.
Fresh off the press, two independent teams have reported finding low levels of methane in the Martian atmosphere. One was using ground-based telescopes and the other used Mars Express data. Although geological sources haven't been ruled out, this is a strong sign of an active Martian ecosystem.
The problem with a sunscreen at that distance from the sun is the enormous thrust you'll generate. You have to find some way to keep ot from becoming a high-speed interstellar probe. A reflective shield that blocks ~85% of the incoming light to Mercury recieves about 2 GIGAnewtons of thrust. For solar shields further out from the sun, you can probably have them held by the sun's gravity but I seriously doubt that this will be practical in this case.
To add, I believe that there's an Earth-Mars trajectory that takes off straight from lunar L1. (there's an interesting if information poor animation on the professor's Marton Lo's website that can be found about halfway down [http://www.gg.caltech.edu/~mwl/communic … tions2.htm]this page.)
I don't know how accurate this anim is but I'm assuming that since they went to the trouble of animating it, they've run a simulation demonstrating the trajectory.
Of course, this wouldn't be used for moving personnel but it's got a lot of utility for moving heavy cargo to the rest of the solar system. The L1 departure point is still a fairly good location for departing astronauts, however, as it allows creew modules to geta refuel before departing on a fast Hohmann trajectory.
I'll have to agree about the tether deorbit idea. Tethers look like a great idea for satellites where mass and volume is at a premium but you're not in any particular hurry to deorbit. The projected deorbit time for the Terminator Tether ™ system from Tethers Unlimited is on the order of weeks to months for a standard satellites.