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If you need a nuclear reactor for power on the surface, wouldn't it also make sense to have nuclear propulsion from the surface into orbit? That would eliminate the hydrogen feedstock and the sabatier reactors. You would simply need compressed carbon dioxide, taken from the martian atmosphere, to run the nuclear thermal rocket. The same reactor could be used for propulsion and power. The only issue I have with this setup is the amount of shielding that will be needed in the tiny ERV. Any suggestions about fixing this problem.
There is a plastic model from a company called Start of a rocket called "Hercules" (maybe Heracles.) This rocket is allegedly the Soviet design for a Mars heavy lift launcher. It has a stretched Energia core and six Energia strap-on boosters. If anybody has more information on this speculative rocket, particularly in the way of drawing and specifications, I would greatly appreciate it.
Is there any way to store H2 in a more dense fashion than we currently do? It would do a great deal to cut down on the structural weight of the rocket if we could. Monatomic hydrogen could be denser than H2, but like somebody mentioned, it's probably not possible to make and store it. Hyrogen's low density makes me favor rocket-grade kerosene or methane for rockets.
It would also be advisable to look for an alternative to Liquid Oxygen, because the oxidizer makes up the majority of the rocket's weight. Hydrogen Peroxide is dense, but it has a lower ISp than LOX and there aren't too many engins that burn it. It's also pretty pricey. The best solution would be using oxygen from the atmosphere. If only we could get a working scramjet or LACE engine...
In terms of "power politics," there is no compelling reason to fly to Mars. The will exists in Russia, but the funding isn't there. I'm sure that Mars is a long range goal for China, but the U.S. will be waiting for too long if we want to race China to Mars. What we need is an intellectual renaissance in America which causes current and future generations to embrace science, technology and achievement. Then we will have the will (along with the pre-existing means and wealth) to send humans to Mars.
I think that cultural stagnation, not some kind of newfound humility, is holding the United States back from Mars. A friend of mine once observed, "We Americans are arrogant, but at least we readily admit it."
I still think that the United States is dominant in the area of space technology, but the Air Force believes that other nations pose a credible threat to its satellites. China is the most likely threat, because of both their ideology and their advancing space program, which may have military goals in addition to its stated scientific ones.
It's looking like this will be an interesting century.
I was thinking about an argument that was made against NTR's, namely that they run much hotter than commercial reactors so they can get the highest possible ISp. I then looked in NASA's report for the 1998 Design Reference Mission. It turns out that the NTR proposed for the mission would run at an incredible 3100 K ! In order to do so, the reactor would use a tri-carbide material that would resist the extreme temperature. This type of reactor had been tested during the Russian NTR program and had run successfully for over an hour before the test was halted.
I'm pretty sure that any manned Mars mission would have to wait for about thirty more years. NASA has been talking about doing a robotic Sample Return in 2016. That would mean a return to earth by 2018. A manned mission would take at least eight more years beyond that date, assuming that MSR worked correctly.
The only way to accelerate the process is a private venture to land on Mars. I'd like to see the Mars Society team up with the aerospace industry to form a company that would colonize and explore the red planet.
Peter, it's great to hear from a fellow Riddler in this forum. I think that Riddle's current students need to play a bigger role in the Mars Society, like the group that submitted the Translife proposal did. I'm interested in your Mars Now paper and want to know where I can find a copy.
Lars, what is your source on the "Chernobyl levels of radiation at every launch" if we went ahead with nuclear thermal rockets? I find it hard to believe that a small (100,000 pound thrust) nuclear thermal rocket would be equivalent to the worst peacetime nuclear disaster in history. No matter how much radiation is released by an NTR, it will all happen either high in the earth's atmosphere or in orbit, above the atmosphere.
Nuclear thermal rockets were the first non-chemical rockets, but politics have prevented us from using them. I don't want to see mankind fail to achieve its destiny in space because we are afraid of nuclear power. If NERVA continued through the 1960's, it is possible that humans would have been to Mars by 1986. Right now, the Bush administration and NASA's chief administrator both support applications of nuclear power in space. Let's seize the opportunity and venture to Mars before this window of opportunity closes.
I think that MSR is very important, but not from the standpoint that it will prove or disprove the existence of life on Mars. MSR will act as a testbed for the technologies that will allow HUMANS to determine whether life existed on Mars. Propellant production, ion propulsion, and direct re-entry, among other technologies, can all be attempted on a smaller scale in a realistic deep-space and Martian environment before they are used for a humans-to-Mars mission. As Zubrin said in "Case For Mars," MSR is like dropping two small robots in the Arctic and searching for fossils. The sampling you receive will not necessarily be representative of what Mars' regolith is like. Even a repeat of the Viking landers using better instruments would not have the range or the intuition available to human geologists and paleontologists.
Yes, ion and plasma rockets have very low levels of thrust, but high thrust is not essential for thier mode of operation. Most of them work for propulsion away from earth and into deep space. It does not need to exert a force strong enough to fight the earth's gravity. As for nuclear thermal rockets, I do not share in your concerns about their safety. I feel that a lot of the guesswork in building a safe NTR was taken out by the Kiwi/Nerva program of the 1960's, and new research will make them a viable and safe form of propulsion.
It doesn't look like there will be a humans to mars mission in the near future if we can trust NASA's recent polls of public attitudes toward space. 60% of Americans are opposed to sending men to Mars, and they control NASA's purse strings and directions. Without the bucks, there will be no Buck Rogers. It seems funny that Zubrin did not give much thought to public opinion when he wrote "Case For Mars." But in Michael Collins's "Mission to Mars," the Apollo astronaut illuminates the problem that the mission will face. I think that the only way to turn the tide of public opinion is with a positive result for life when we finally retrieve samples from Mars.
I'm thinking that the "Buran" being auctioned is a mockup or a static test article. The radio station has stated that this particular Buran is NOT the Buran which made the type's only spaceflight.
I definitely think that space tourism will drive CATS. Most people cannot afford to be a Dennis Tito or a Mark Shuttleworth, but the will to fly in space is certainly there among the public. The Cosmopolis rocketplane, currently being studied by Space Adventures, will hopefully give more people an affordable opportunity to experience space. If Space Adventures is successful, more companies will follow, and we will see CATS within our lifetime.
On a related note, a Los Angeles radio station is auctioning off a Russian shuttle, with a starting bid of $6 million. Assuming that the orbiter is spaceworthy, or if it could be made spaceworthy, could Russia restart production of Energia so the owner could use the shuttle as a space tourist vehicle?
In NASA's current MSR scheme, the sample container is left in LEO to be retrieved by a shuttle. The shuttle will then land at an isolated site like White Sands so the samples can be studied. The plan sounds okay to me from a safety standpoint (its far better than cooking the samples, like some have suggested.) It also avoids the contamination of the samples that may occur if the canister makes a landing by itself at land or at sea.
Still, it's unlikely that living organisms will be in the Martian soil. The best place for life to exist would be subsurface water. According to Mars Odyssey, the planet has plenty of it. I can imagine that Mars has an ecosystem similar to that found near the undersea vents on earth.
It is imperative that the scientific community try to retrieve samples from Mars as soon as possible. Even if the tests for life come up negative, the mission will pave the way for humans to Mars.
The only problem with MSR is that none of the space agencies are committed to launching the mission. MSR is no longer a NASA priority, and I doubt that NASDA or ESA will launch the mission before 2014.
What can we do to make MSR happen? I know this is very optimistic, but I think that the Mars Society should raise the money for it and conduct the mission for themselves. If Translife is a success, this scenario will be a definite possibility. MSR will be expensve, but only the Mars Society believes in using in-situ propellant production for MSR, and it will be essential to test this technology on Mars before attempting a humans-to-Mars mission.
The ISS just might be completed after all, and the X-38 might be made redundant.
The X-38 was intended to act as an ISS crew return vehicle. But a similar "crew taxi" is being developed for the Space Launch Initiative. It is a strong possibility that the SLI crew taxi will serve double duty as a rescue vehicle for the ISS. It has also been suggested that Italy could adapt its pressurized logistics module to act as accomodations for an additional three or four astronauts.
There is hope yet for the ISS.
I wanted to go back tn an argument I had made previously about fuel costs being a barrier to space access. I was reading "Case For Mars" the other day and Zubrin prettymuch shot my argument out of the water. In his example, using a methane-fueled SSTO to reach orbit, it would burn $14 of fuel for every pound placed in orbit. The key to an economical RLV, then, is simplified maintenance and a fast turnaround. Still, space access could be made even cheaper if we built an air-breathing aerospace plane.
We have to ask ourselves why we abandoned the moon, and how we will avoid repeating these mistakes when we go to Mars. I see at least three reasons for the failure of Apollo to establish a lunar colony:
1. Excessive cost. Any lunar base would beed a transportation architecture that is much cheaper than launching a Saturn-V class rocket for every excursion.
2. Propaganda ahead of science. If Apollo had science and not Cold War rivalries at its heart, it would be easier to justify its expenses. However, it was quite valuable in that beating the Soviets to the moon was a major cause for the collapse of the Soviets (If you believe Tom Wolfe, Mercury ended the Cold War.)
3. Changing national priorities. In the United States, social programs, war in Vietnam, and the environmental movement sapped the funding and support from Apollo in the early 1970's. Any government-backed space exploration effort will suffer from the same problems. Perhaps that is why Zubrin backs private enterprise. An interesting alternative would be the formation of a "Mars Corporation" that will settle and explore the red planet.
I certainly disagree with "American Imperialism," as America was never intended to be an imperial power (despite our dabbling in imperialism during the end of the 19th century.) If a Russian booster is the key to getting to Mars, we should not be so foolish to reject it. And once foreign powers are ready to colonize Mars, we should encourage them rather than forcing them join with us.
However, I am convinced that the first mission to Mars will be financed and manned by America alone. We are the only country that has been to the moon. The same spirit which drove America to put men on the moon will enable us to travel to Mars. The first footsteps on Mars will then open the floodgates for more nations to follow.
If a "Sea Dragon" type booster is built, it should definitely use hydrogen fuel for both stages, for the simple fact that the hydrogen can be obtained from the sea water at zero cost. RP-1 kerosene would represent a greater expense.
I am in favor of a USA-only Mars expedition for many reasons, the largest of which is the example set by the ISS. If an international Mars program faces the delays and waste that ISS does, we should forget about it. Another reason behind my "America only" stance has to do with a belief that America is the "New Zion." America is the greatest nation because we descended from the British empire, which in turn was originally founded by the Roman empire. If a new "promised land" is to start on Mars, it will be the United States that sets the ball in motion.
Boeing, Lock-mart, and Northrop Grumman/Orbital Sciences have released fifteen images of what the next space transportation system may look like. The most intriguing concept comes from Northrop Grumman. A two stage, reusable rocket is carried by a flying wing from the runway to launcyh altitude. After its climb, the rocket fires its engines and the wing falls back to earth. I particularly like the idea because it eliminates the problem of ferrying the orbiter, and it has more flexibilty than a system that takes off from a fixed launch pad.
I guess I wouldn't yet be one of those "more technical people," but I might be able to weigh in on this. Most rockets are approximately 90% fuel by mass. When you drive a car or fly an airplane, you do not think of the cost of fuel as being a significant portion of the vehicle's cost, because neither vehicle has a fuel fraction as high as the rocket. But with the rocket, it's structure makes up less of the total cost of flying the vehicle.
By building inexpensive structures instead of rugged, reusable ones, it might be possible to build an expendable booster that is cheaper than a reusable one. Materials like steel, while heavier than aluminum, are cheaper to produce. It is also lighter and cheaper to develop a pressure fed engine instead of clustering existing pump-fed engines for the rocket.
I do not think that enough studies have been done comparing the virtues of "big dumb boosters" and RLV's. Certainly, the Space Shuttle has not been run in a cost-efficient manner like it should have, and we have yet to build a commercially-viable big dumb booster.
Within the next year I hope do do some research with a small pressure-fed engine, similar in concept to the engines that Andrew Beal tried to develop for his big dumb booster. When I am done I will be more than happy to share my experiences with this forum.
NASA had actually planned on an ISS that wold be launched as a single main piece aboard a shuttle derived rocket (with the station taking the place of the shuttle orbiter.) This was one of three configurations NASA looked at; it was probably rejected because it made too much sense. The final ISS design makes extensive use of Russian core modules originally designed for Mir-2. This decision was probably made to reduce the amount of R&D that America would have to spend on ISS.
I wentto the awesome Encyclopedia Astronautica (www.astronautix.com) and got some more details about General Atomics' Project Orion. The bombs would be detonated 200 feet behind the vehicle's pusher plate, and each would have a yield of 0.1 kilotons. Apparently Von Braun backed the idea, but not even a man of his influence could convince NASA that it was a good idea.
I don't know much about atomic bomb yields, but I'm pretty sure that we have some tactical nuclear weapons with a similar yield.
Anyone up for swing around Mars?
Let's just build Sea Dragon.
Proposed by Robert Truax in the 1960's, Sea Dragon was over 450 feet tall, and could put 550 tonnes into LEO. It would be towed by a nuclear-powered ship (possibly a retired aircraft carrier or submarine) to an equatorial launch site, where a plant onboard the ship would electolyze the sea water into hydrogen and oxygen fuel. The rocket would then fill its attached launchpad with water for ballast and take off directly from the sea.
Sea Dragon would be cheaper than similarly sized boosters because it would be built in a shipyard from maraging steel, and it would use pressure-fed engines. Furthermore, no new launch pads would be built to support Sea Dragon. When we finally decide to go to Mars, Sea Dragon will spare us the trouble of on-orbit assembly while still providing the crew with adequate equipment.