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The hab is 8 meters/25 feet in diameter, has two levels each with about 50 square meters/500 square feet, and has a TOTAL mass of 25 tonnes, but that includes supplies, furniture, a pressurized rover, and scientific equipment. The structure is given as 5 tonnes, the life support system as 3 tonnes. ...The ERV cabin has a 3 tonne mass with a 1-tonne life support system.
For life support, 3 tons is a bit light for a 4 person P/C LSS, but it might be achievable with some more development (though the power plant to run it would also be several tons). Expecting to only need 1 ton for a 4 person P/C LSS is just foolish. What I don't understand is if Zubrin realized that it would weigh at least 3 tons on the fist hab, why did he think that he could get away with only 1 ton on the ERV?
The only really new things are trading out the venerable but underpowerd RL-10 with the new RL-60,
Boeing will want to use their own engine, so that will be MB-60 rather than RL-60. It looks like they are planning to do this modification whether it is required for VSE or not.
I think that it will end up using 3 launches of an upgraded Delta IV Heavy.
The requirements description also mandates that the CEV design be expandable.
What do they mean by that?
Why exactly are the mass estimates so off the mark? Zubrin estimates that the hab and ERV will each be about 60,000 pounds, that seems logical to me. If you look at the estimates, everything is accounted for, along with a 16% margin for mass gain.
60,000 lbs for a four-person hab is smallish, but may be workable. However, I think that the habitable part of the ERV needs to be about the same size as the hab because it provides essentially the same function. In the Mars Direct scheme, the ERV must also include some big rocket stages, hydrogen feedstock, a nuclear reactor, etc. so that the habitable part of the ERV ends up being much smaller. The Mars Direct scheme gives the ERV a mass which compares unfavorably with small real life 3-person space vehicles such as Soyuz, Shenzhou, and the Apollo Command/Service modules, despite the fact that is must carry 4 people on a much more difficult mission. There are also some other objections to Mars Direct, but I think that this is the one 100% irrefutable reason why the current Mars Direct plan would not work.
That drawing of the Mars Society hab would be perfectly acceptible for a mission with a crew of four, IMHO of course. Compared to the U-boats that operated in WW2, that would look positively spacious, and many of the enlisted men on the crew would never see daylight in tours as long as a mission to Mars.
Compared to the ERV, it would definitely be the U-boats that look spacious.
I don't think that any of those would help unless the efficiency of the ionic breeze engine improves substantially. You need a high specific power, rather than just a high specific energy.
If you disagree with Dr. Z (as he seems to be called), fine, if you can argue successfully why he's wrong. I haven't seen someone do that satisfactorially yet, but I suppose I could be proven wrong at any time.
Look at Zubrin's mass estimates for the ERV. Even if you assume his mass estimates for the launcher and the propellant production factory are accurate, that still leaves you with an ERV crew capsule that is lighter than Soyuz. And it is supposed to keep 4 astronauts alive for 6 months? It just won't work, and there is nothing that you can cut on the ERV to improve the situation.
Since the ERV makes its propellant on Mars it will be able to return substantial amounts of samples to Earth, this is still viable stuff.
No, you can't take much back to Earth. I don't think that the ERV would be able to get the astronauts back to Earth even if they did not take any samples with them.
What is the thrust rating for the RS-68 by the way?
Isn't it the second most power liquid fuel rocket engine ever produced by the United States? Second only to the F-1
The RS-68 has a rated thrust of 337,807 kgf. That is the largest LH2/Lox engine that has ever been used on a launch vehicle. A larger Lh2/Lox engine called M-1 was developed for a possible successor to Saturn, but the program was cancelled and it never flew. The only other larger liquid engine produced by the US was the F-1, though the RD-180 used on the Atlas engines is a little bigger, and theoretically it will also eventually be manufactured in the US.
Which would be cheaper to develop, build, mass produce and man rate?
I suspect that the Super Ares would be cheaper to develop, since it uses mostly modern components rather than trying to revive components that stopped being used a long time ago. The Super Ares should also be much cheaper to operate, and it would probably be safer. It is a much better option than trying to revive Comet.
A better comparison would be between Super Ares and a comet-like vehicle that switched out some 60's parts for modern ones. However, I think that Ares style vehicle would still come out on top.
It seems this uses the http://en.wikipedia.org/wiki/Biefeld-Br … feld-Brown Effect. There are a few people who are still working on it, but there has not much progress on improving it's efficiency since the article was written. However, modern capacitors are light enough that a vehicle could be built using current technology which could lift its own power supply for a brief amount of time(a few seconds.) A lot of the fundamental physics involved are still not well understood.
Ion engines achieve high exhaust speeds in low vacuum;
But only 3 to 4 meters a second on Earth. On Mars, pressures are lower, which would allow for a higher exhaust velocity.0.96 hp. per pound, as compared with a typical 0.1 hp per pound of helicopter or 0.065 hp for a pound Piper Cub
I would like to see calculations for Martian conditions.
You actually want the exhaust velocity to be low, since that will increase the amount of thrust you get per unit of energy. However, if you try and get the velocity too low, you will end up without producing a significant amount of thrust. Another thing you have to consider is that the size and shape of the coronal glow would change due to the reduced amount of pressure. So how would a optimized Martian ionic breeze system compare with an Earth ionic breeze system? I don't really know, and I have not been able to find any sources that give a clear answer on that question. Anyone have a vacuum chamber that you can use for some experiments?
http://www.chinadaily.com.cn/english/do … .htm]China, ASEAN work towards creating world's largest free trade area
Russia doesn't have a future strategy, and Russia hasn't been making "smart investments" or whatever...
Just because Kliper only goes to LEO does not make it worthless. It will have double the capacity of Soyuz and has the potential to make human access to space cheaper and safer. That could be useful for a wide variety of projects, and it would improve utilization of the ISS.
Kliper is not a panacea, but that is also the reason why it is likely to work. It will provide a modest improvement in Russia's spaceflight capabilities, which is about as much as Russia can hope to do considering their budgetary restrictions. I think that building Kliper is a good investment for Russia.
I don't follow. The debate was my idea of using the MAV as the TEI stage vs. NASA's DRM that sends propellant for TEI from Earth. Both systems leave the ITV in Mars orbit. Life support and consumables are the same. NASA's DRM uses ISPP for the MAV anyway, so using the MAV for TEI just means a larger tank, ascent engine, and feedstock. The enlarged mass for the MAV is less than the additional propellant, larger tank, and TMI stage for the ITV.
Sorry, I thought you were using the MAV as the ERV like Mars Direct. Doing it your way certainly seems more reasonable than Mars Direct, but I am still not sure if it is better than just having a fueled ERV in orbit. Do you have any calculations of how much fuel you will have to bring up?
The two options are to carry fuel for return to Earth from Mars surface, or from Earth surface. Mars surface is closer to LMO and Mars has lower gravity.
The problem with this is that you have to send feedstock, a nuclear reactor, and automated fuel production facility, a really big rocket stage, an interplanetary hab, an Earth descent module, consumables, life support equipment, aeroshield, radiation shielding, etc. all the way from Earth to Mars surface, and then you have to launch it all the way back to Earth. And it has to be reliable enough to survive several years in a hostile environment and launch without any maintenance. While you can get a lot more of your fuel from Mars' surface that way, the total fuel requirement for the mission will be much higher, and the total risk will be higher as well.
The technical challenges of building such a vehicle are simply too difficult, and most likely neither Energia nor Ares would be able to launch it.
Can Boeing launch two Deltas within a month of eachother?
The launch pad that Boeing built for Delta IV is designed for 15 launches per year, so it should be possible. Still, I think that using HLLVs would be a much better idea because it would have lower reoccurring costs and lower risks. Plus, you are using an HLLV to launch the ERV anyway, so why not use it for all launches?
China recently http://www.guardian.co.uk/uslatest/stor … l]launched the first submarine in it's new "type 94" class nuclear powered ballistic missile submarines. This new class represents a very significant improvement in Chinese capabilities, and it will be much quieter that China's previous submarines. It will carry an estimated 20 of China's new JL-2 missiles with a range of at least 4,600 miles, meaning that it's range will cover most of the US even if it stays in Chinese territorial waters. Western experts knew that China was working on type 94 submarines, but most did not expect the first one to be launched for several more years.
Mars Direct was estimated to cost $30 billion for 7 missions in 1990, although in public Robert Zubrin keeps saying $20 billion for an unspecified number of missions. NASA's Design Reference Mission was estimated at $55 billion. That's significant cost creep, and without building any hardware; it demonstrates the need to keep cost under control.
If we have to choose one mission and stick to it, we should choose the http://cmex-www.arc.nasa.gov/CMEX/data/ … ]Reference Mission. It is much more feasable and less risky than Mars Direct, and it is already approved by NASA. $55 Billion is a very reasonable price for a mission that is likely to work.
BTW, could someone check my math on this? I was expecting the parachute to be big, but not THAT big.
Uding your equation, I get a value of 36.5 m^2/kg, or 1/27 as large as your parachute. The hab would therefor need a parachute of "only" about 1 km^2.
Having humans on Mars controlling robots gets you the worst of both worlds. You need to spend a lot of resources to keep the humans alive and the robots working, and the robots still will not be as dexterous or versatile as the humans themselves.
On ISS, when something needs to be fixed or installed, they do not send a robot to go do it; they send out an astronaut. The surface of Mars is much more hospitable to humans than LEO, though it is arguably less hospitable to robots. Humans will end up doing most of the work, not robots.
But the amount of energy the wind provides increases by the square of the velocity.
Actually, the amount of energy that the wind provides increases with the cube of the velocity.
I doubt high-speed rotation in high winds is a structural problem; helicopter blades turn much faster.
Helicopter blades are also a lot smaller than the blades of large windmills. If you increase the length of a rotor while keeping it spinning at the same rate, then the strength of the materials that you are using would have to increase proportionately to the square of the blade length.
High speed rotation is a problem for large windmills. It is the reason why modern large-scale windmills use carbon fiber or fiberglass blades. It is also one of the reasons why windmills must tilt their blades so that less power is produced in high winds.
Near Earth asteroids are the easiest targets. In fact, they are much easier than Mars and arguably easier than the Moon. We could even see a trip to one before astronauts go to Mars. However, all of these would be short Apollo style missions and I don't see any asteroid bases or colonies happening any time soon.
For Venus, the pressures, temperatures, and chemistry should be enough to keep humans away for a very long time.
Mercury is much easier than Venus, but it is still not really very hospitable and the solar flares will be pretty nasty that close to the sun. It will get a low priority.
Jupiter's icy moons are the next easiest targets. With a Hohman transfer orbit, it would take 2.8 years to get to Jupiter. It will be a long mission, but it should be doable without any major technological advances.
Titan comes after Jupiter's moons. A Hohman transfer orbit would take 6 years to get to Saturn, and there would be almost no sunlight. It does have the advantage of an atmosphere that is 1.6 times as thick as Earth's, but you would still need oxygen and it would be extremely cold. Overall, I think that it would be significantly less hospitable than Mars, and it will defiantly require some advanced space nuclear reactors.
double post
For use in the atmosphere, could you use a more conventional explosion initially to create a vacuum in the combustion chamber, followed quickly by a 'machine-gun' succession of antimatter/fusion explosions. The frequency of the detonations might keep the chamber clear of atmospheric gases until orbit is achieved(?).
I don't think that you can create a good vacuum through explosions. You might get rid of the atmospheric gasses, but you introduce new gasses with each explosion.
Klipper would not be able to fit on the current R-7 boosters anyway, so it would make some sense to adapt it to Ariane V rather than designing a new booster.
If you want to get an efficient reaction, then your antimatter will have to hit the Uranium/Lithium Deuteride spheres from all directions in a small fraction of a second. You can't just point a beam of antimatter at a block of Uranium and Lithium Deuteride and expect it to produce a worthwhile fusion reaction.
Even if you solve all of the antimatter production and storage obstacles, there is still a long way to go before you have a practical engine. I think that we will see ordinary fusion engines become successful before we get antimatter catalyzed fusion working.
Sure they can do it for less money absolutely, but can they do it for a smaller portion of GDP? I doubt it. So "cheaper" is a relative term.
If they can do it for less money absolutely then they can defiantly do it for a smaller portion of the EU's GDP.