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Solar sails are good for some things, but they don't really scale up very well, so they are not a good choice for human missions. They also cannot perform their best on missions to the Moon or Mars, so Solar Sails are not a very VSE friendly method of propulsion.
DC-X/DC-Y/DC-I probably would have had a better chance of succeeding than the X-33/VentureStar concept; with our current level of technology, wings are simply too heavy for any practical SSTO to carry. However, I doubt that even the DC-I could have become a successful launch vehicle. The vehicle would have to stretch the limits of technology so much that it would have the same sort of cost and safety issues that have plagued the shuttle, only more so.
Japanese military and space equipment generally costs more than equivalent US equipment, not less. Setting up an advanced industrial capacity requires a lot more equipment than many people seem to think, and it gets much worse if you stupidly build humanoid robots rather than using a simpler and more efficient design.
The Japanese Moon base plan looks like pure fantasy.
ESA pledges to support Kliper. http://www.spacedaily.com/news/rocketsc … .html]link
Radial velocity measurement has improved a lot in the last couple of decades. 30 years ago, 1 km/s was state of the art. However, this technique may not improve very much in the future. Apparently stars have internal vibrations of about 1 m/s, so even if the instrumentation improves beyond that point it would be difficult to distinguish the planet's influence from these vibrations. Also, it should be noted that while the Gliesse 876 is probably only 6-9 times as large as Earth, Earth would be about 50-100 times more difficult to detect using this method. This is because planets that are close to their stars cause their stars to undergo a greater change in during each orbit than planets that are far from their stars, so a .5 Earth-mass planet at .25 au is as easy to detect as Earth. In addition, Gliesse 876 is significantly lighter than Sol, meaning that its velocity will change more than a heavier Star's would with planets orbiting at the same distance.
In order to detect planets like Earth, other methods are needed. This http://en.wikipedia.org/wiki/Image:Extr … .png]graph shows the sensitivity of some of methods of finding planets. COROT and Kepler are transit surveys, so even though they are very sensitive they can only detect planets if they pass directly between the star and the telescope. Gravitational microlensing surveys are also very sensitive, but again they rely on luck and are unlikely to find planets around nearby stars. Most of the planets that have been found were found by the radial velocity method, and you can see what 3 m/s and 1 m/s instruments can detect. Astrometry is the oldest detection method, with attempts at finding planets going back 60 years, though the technology has not been good enough for this method to succeed until recently. This is the method that I think is most likely to find Earth-like planets around nearby stars.
Astrometry works by measuring the proper motion of stars. This works best on nearby stars, and the sensitivity decreases in proportion to distance. 3 parsecs is about 10 light-years, so the SIM mission with an angular resolution of 1 microarcsecond would be able to detect an Earth-like planet that is 10 ly away. Unlike the radial velocity method, it is actually easier to detect planets that are far away from their stars than it is to detect planets that are close to their stars(provided that the planet has time to make a complete orbit during the duration of the study).
Eventually, directly imaging planets may also become a good method of finding planets.
Now, considering countries like the United States, Britain, and Australia etc. have stepped up to the plate and done the right thing, even in the face of the mindless loud protesting of the amoral Left, perhaps it's time for the U.N. to put its honour where its hypocrisy is and insist on French, German and Russian troops on the ground in Sudan. Hell, let's get Chinese troops in there, too!
I am pretty sure that you could get French troops to support an intervention in Sudan, though I am not sure about the Germans or the Russians. The Chinese already have troops in Sudan, the problem is that they are sort of on the wrong side. That is the reason why it is so hard for the UN to do anything about the situation.
No I have to disagree with you on this, For more than 30 years there have been a lot of people with very good engineering and science skills coming from the Universities and colleges of India.
Yes, but for the last 30 years there have been a lot more people with good engineering and science skills coming from the universities in China.
What India has is a weakness in indigenous Launchers and in the making and advancing of them. In this China with its long march are way way ahead.
This is clearly true. However, the same official who was saying that India was a step ahead in satellites also said that India was equal with China in terms of rocket technology. How can you assume that the official is correct in one of his claims when he is clearly wrong in another?
I have noticed that a lot of Indians believe that it is patriotic to exaggerate their accomplishments to an absurd degree. This looks like just another case of hyperbole. I think India is still far behind China in most areas of satellite technology.
What about someone like John Carmack? Armadillo Aerospace still has a long way to go, but if they do end up accomplishing something worthwhile I would consider Carmack a hero.
You should not stereotype millionaires. Not all of them have always been rich, and not all of them care only about making money.
Thats not entirely true MR... Martian Tristar here is talking about a NERVA NTR engine, a nuclear rocket engine. With one of those, then a SSTO spaceplane on paper starts looking much more plausable. The trouble is, of course, the radiation: that shielding for the crew would defeat the mass savings of using an NTR engine, and if there were a failure... well... lets just say that you don't want to be down-wind of the crash site for a few years. The size of the NTR engine needed would also be quite large and might itself present weight problems. The extra-large liquid hydrogen tanks would be a drag/reentry problem too.
Radiation shielding for the crew should not be a huge problem. The most natural configuration would put the crew in the front and the engines in the back, meaning that almost the entire vehicle is acting as a buffer between the two. It also makes sense to use NTR in a horizontal takeoff/landing vehicle, because that means the engines can be smaller as it does not need a T/W ratio greater than one. However, the environmental problems are still considerable.
Isn't GCNR a chemist?
Better performing jet engines maybe? If this could get to 100,000 feet and mach 3 on two jet engines alone then fire up the SSME's, they produce 100,000 more pounds of thrust in a vacuum.
It won't make enough of a difference. Your vehicle still would not be able to get anywhere near orbit. There is a reason why the STS is 90% fuel at launch. It has to be, or it will not be capable of getting into orbit. Even starting at mach 3 and 100,000 ft, your vehicle would still need a mass ratio almost that high to get to orbit.
Both drag and gravity apply to solar sails just as much as they apply to other matter. I don't see how changing your balloon into a sail will help you.
The studies seem to indicate that a new telescope would deliver significantly more capability than Hubble, while being less expensive and less risky than a Hubble servicing mission, and would probably last longer than a refurbished Hubble as well. In light of these facts, does anyone dispute that it would be a much better investment in terms of science/dollar to build a new telescope than it would be to service Hubble?
If you accept that the HOP is a better investment, why continue to support Hubble? When it comes down to it, funding for astronomy is really a zero sum game, so if you want to preserve Hubble then you will just be delaying the production of something better.
Dook, you won't be able to make any useful contributions to discussions about launch vehicles until you familiarize yourself with the http://en.wikipedia.org/wiki/Rocket_equation]rocket equation. The constraints placed on rockets by the rocket equation mean that an orbital launch vehicle’s mass will always consist mostly of fuel. In fact, there has to be so much fuel that most of the non-fuel weight will be taken up by fuel tanks. If you ignore fuel and fuel mass ratios and instead only concentrate on engines and thrust, your designs probably won’t be capable of reaching orbit.
I still have to work out the hyd/oxy storage and useage. It very well may not work.
For a typical SSTO using O2/H2, the fuel and oxydiser take up close to 90% of the total vehicle weight. Basically you will need 100x more fuel than you were expecting to use.
We don't have to worry about running out of electrical power in the near future. Coal and Uranium should last for at least 100 more years, while wind and solar can supply enough power at a cost that is only slightly higher. The problems with scarcity that we will have in the near term are shortages in oil and natural gas. There won't be any problems in making sufficient energy, but there will be problems finding cheap alternative chemical feedstocks and compact, efficient methods of storing energy.
I think that magical uber-fabbers are still a long way away. However, with our transition into an information economy, we are already seeing threats to the traditional capitalist models. The simple fact is that it is not very efficient to try to buy and sell packets of information, as the marginal cost of the information is essentially zero. It would be much more efficient if all information were free and open-source, but that runs into another major problem: there needs to be a way for the people who created the information to be compensated. One way to solve this would be for people to give donations for information they find useful, but it seems doubtful that people would be altruistic enough for this system to work well. Another option would be for the government to employ people who create the information, but that does not seem like an optimal solution either. Can anyone think up a good solution to this problem?
Space is really pretty empty. I think that the chances of a collision are low enough that we do not need to get too worried about it.
launcher GTO payload
Ariane 5g 6,800 kg
Ariane ECA 10,500 kg
Ariane ECB 12,000 kg
Delta IV heavy 12,757 kg
Did they reduce the estimated payload for the Delta IV recently? I thought it used to be 13,130 kg, but now Boeing's site says it is 12,757 kg, and Astronautix says that it is only 10,843 kg.
Ariane ECA is smaller than a normal Delta IV heavy. In fact, even Ariane ECB is still slightly less powerful than Delta IV heavy.
The requirements are deliberately ambiguous. Notice how it says CEV system rather than CEV capsule or CEV module. Basically, the draft key performance parameters just says some part of the CEV system has to land on the Moon.
The Russians either expect the ISS to last longer than you believe that it will or they believe that they will still be sending people into LEO after ISS is gone. Probably both.
Russia has continued to make improvements to Soyuz so it is the best expendable spacecraft ever built.
What about Shenzhou?
I found a US government web site that stated the cost of Soyuz-T/TM: 95 million Rubbles in 1992. Today's exchange rate is 28.075 Rubbles = 1 US Dollar, so that makes the spacecraft $3.38 million plus 13 years of inflation. Try to match the reliability, mass per astronaut, or price.
The plus 13 years of inflation is a pretty big factor here. With the hyperinflation of the mid 90s, the Russian ruble decreased in value by a factor of more than 10,000. This was partially corrected on Jan 1, 1998 when the Russian government increased the value of currency by a factor of 1000. However, 95 million rubles from 1992 should still equate to well over $100 million of today’s dollars.
I would be interested to see a breakdown of the shuttle army to determine what percentage of those folks work exclusively with the orbiter.
The entire "hardware" segment of the Space Shuttle budget is a little less than half of the total. About one third of the budget is used for "flight and ground operations", and the rest is split between "program integration" and R&D. Hardware includes procurement and refurbishment of all flight hardware and software. Operations includes final assembly of the shuttle stack, mission control, astronaut training, aircraft support, life sciences work, etc. Program Integration works with the payloads and does some management work.
I have not been able to find a more detailed breakdown than that. The current NASA budget does not even show how much money each category is getting, so the amounts in each segment are just what I remember from previous budgets.
![http://en.wikipedia.org/wiki/Image:Extr … .png]graph](http://en.wikipedia.org/wiki/Image:Extrasolar_Planets_2004-08-31.png]graph){kind=link}