Nibb31

And putting a CubeSat in GEO is going to cost a lot more. I don't even think there are any upper stages with provisions to carry CubeSats to GEO.

Paying for a space program funds highly-qualified domestic jobs. Those people then spend their money and pay taxes locally. It also provides a purpose for the education and science sectors, which also creates a lot of work and generates revenue. Without a domestic space program, those engineers and scientists would have to find work overseas, where they would spend and pay taxes. Their contribution to India's economy would be minimal and India would stagnate technologically.

It's probably not feasible to go and rescue a stranded astronaut with a Soyuz. Soyuz does have an EVA hatch on the orbital module which can be depressurized for contingency situations, but no handrails for the astronaut to hold on to. You would need a second astronaut doing a stand-up EVA from the hatch to try to catch the stranded astronaut. Even then, I'm not sure that a US EMU suit could fit through the small EVA hatch of the Soyuz, or if two suited astronauts could fit inside the Soyuz orbital module. Neither Dragon, Dreamchaser, or CT-100 are EVA capable, so they would be useless for a rescue. I don't think that would ever happen anyway. The probability of a tether breaking or an astronaut forgetting to attach it are already very slim. This is basic life-saving training that is hardwired into their brain. Then combine the probability of the SAFER failing, and the probability of drifting too far for the second astronaut (they always EVA with a partner) to catch with his own SAFER. We must be talking probabilities in the 1:1,000,000. SAFER is the rescue method. No need for another one.

As you have seen, NASA astronauts are equipped with SAFER. If the astronaut was incapacitated or if the SAFER mulfunctioned, the contingency plan was to manoeuver the Shuttle to catch him in the payload bay. I don't think there is such a plan with the ISS.

The links I posted earlier about TRL levels, did you read them? It's not the first time you've claimed that you would be happy to off yourself or others for some sort of delusional cause. I think you should be seeking help instead of posting on forums.

I suggest watching Children of Men (2006), the first movie from the guy who directed Gravity. It depicts a world where Humanity has become sterile (due to pesticides, disease, or some other unexplained cause). There are no more children and there is no tomorrow. It's a great movie for pessimists like me

Why would you want to waste actual payload weight by carrying wings all the way to other moons or planets? Because: - They are damn expensive to build. - They are damn expensive to maintain. - They would have nothing to do.

Simply being at a similar orbital distance as Earth doesn't make a planet habitable. We lack data to extrapolate statistics. The only model we have is our own solar system. But yes, it is statistically probable that among the billions of planets in the galaxy, there might be some that are like ours. It's all hypothetical though, because there is no way for us to ever go there or even communicate.

Stop saying that. Thank God you're not.

I don't know what you call "no fatalities", but the Nedelin launch pad explosion killed 90 people, and 4 cosmonauts were killed in-flight (Soyuz 1 and Soyuz 11). My point was that those accidents are well known nowadays and widely documented, so it's a bit far fetched to think that the Russians are still hiding any space accidents from the Soviet era.

Goldenpeach was referring to an incident during the launch that was unrelated to the oxygen tank explosion. One of the second stage engines suffered a shutdown. The other engines and the S-IVB burned slightly longer to compensate and they got into orbit fine.

No. The F-1 and J-2 engines were not restartable. Restartable rocket engines are quite more complex, so that level of complexity is only implemented when necessary, for the S-IVB or the CSM for example. The Shuttles OMS engines were restartable, but not the SSMEs. The reason there was propellant left in the stages is because it's preferable to shut down the engine with a bit of extra propellant at the end of the burn than to run out of propellant prematurely and starve the engines. Turbopumps don't like starvation and can fail catastrophically. The S-II kept on burning at low throttle in order to maintain positive acceleration for a clean separation event. You don't want things accelerating and decelerating all over the place. Also, rocket engines take several seconds to cut their thrust. It must have been around 2% throttle at separation time. The actual staging sequence was something like this: - S-IC burn for a pretermined time. - Cut off S-IC engines. - Fire explosive charges for S-IC separation. - Fire ullage motors on the interstage. - S-II engine ignition - Fire explosive charges to jettison the interstage. The interstage was jettisoned separately because they were afraid about the clearance with the J-2 engines. If it had stayed attached to the spent first stage, they were afraid that it might hit the engine nozzles. The interstage itself contained the ullage motors and was a heavy piece of kit that needed to be jettisoned. Failure to drop it would have prevented the rest of the rocket from reaching orbit. The ullage motors were small solid rockets that gave a jolt to the S-II (and S-IVB) before main engine ignition. This was designed to settle the propellant at the bottom of the tanks to prevent cavitation in the turbopumps, which could be catastrophically destructive. As you can see, the whole sequence is a tad more complex than "press space"

Rubbish. Scientific method requires that for a technology to be available, it needs to be demonstrated. You should read about NASA's TRL process: http://www.nasa.gov/topics/aeronautics/features/trl_demystified.html http://en.wikipedia.org/wiki/Technology_readiness_level The concepts that you keep on suggesting on a regular basis are TRL 2 or 3 at best. In order to be seriously considered for a mission involving actual astronauts, it needs to be at least TRL 6 for a prototype auxiliary system. For something as vital as life support or propulsion, you will need to reach TRL 8 if it is mission-critical. I've already told you this, but I'll say it again. If YOU want to propose the use of a technology, YOU need to demonstrate that it has reached the appropriate TRL. It's not up to ME to prove that what YOU are proposing doesn't work. Besides, what I said was that a viable self-sufficient Mars colony is impossible with current technology. I believe that a semi-permanent lunar outpost with a crew rotation and a regular line of supply is probably feasible. However, not something large enough to survive an extinction event with genetic bottleneck. Yet a large portion of Humanity is still living in the 19th century today. And if you had told someone from the 19th century that we could grow wings and fly, he wouldn't beleive you either, and he would be right. The ISS was impossible in 19th century. I'm not saying that it will not be possible in 200 or 300 years, but really that's irrelevant because anything can happen by then. Civilizations rise and fall in that sort of timeframe. We might have all mutated into some sort of cybernetic singularity for all we know... I sincerely don't know. My guess is that if you built them at something like a kilometer deep, bunkers within a certain range of the impact site would probably not survive, but a majority of them would. After the impact, the major problem would be firestorms on the surface that would rage for several months and cause a nuclear winter. After that however, if you have working life support, communication, transport, hydroponics, stockpiles of supplies, wind power generators, you might be able to save enough population to survive a genetic bottleneck event.

A dozen solar farms around the equator can provide power 24/7 and will always cost less than a solar farm in geosync. An orbital solar plant would be limited by launch capacity to GSO. The current heaviest sat in GSO is ~7 tons. SLS might provide the capability for 20t to GSO, but it can't be used for commercial launches, so that's moot. On Earth, you can just add panels to increase production or to compensate for any loss. Also, the technology to beam high power from GSO to the ground without major loss or side effects is absolutely not proven. Not really. Most solar panels are rated for 25 years on Earth. The ISS Solar Array Wings were designed to last 15 years. In space, they are subject to MMOD damage. On Earth they can be cleaned and are easy and relatively cheap to replace. A repair in space would be expensive, especially at GSO.

Not when paying for it means raising taxes or diverting funds from some politician's favorite money sink or corporate interests (real estate, insurance companies, banks...). When that happens, you will start seeing lobbies and interest groups paying for independant studies that will prove that the asteroid threat is a myth so that those corporations can still publish good results for the next quarter. Doesn't that sound familiar? There would also be arguments about what to do and how to do it, where the priorities would be, who would be in charge of the global effort, who gets saved and who doesn't, who gets to be in charge of your colony, and all that sort of thing. There is no way we could all come together and agree to divert a major part the World's resources into a single project like that. It would take years just to get some sort of general agreement treaty. Comparison with Apollo is not relevant. It was a single country's effort and it had very little impact on the World economy. It wasn't in response to a threat, it was a demonstration of technological superiority which was chosen because it was considered technically feasible. We've already explained to you dozens of times that building a colony of several hundred people on the Moon is simply not possible with current technology. Let's not have this argument again. A colony of a few hundred (or even a few thousand) individuals on Mars has less chance of long-term survival than hundreds of colonies in underground bunkers scattered around Earth. Any life support technology that would work on Mars could be built on Earth for much less cost and effort, on a wider scale, and saving much more people. It would be a much more feasible survival technique than developing Orion drives, terraforming Mars, inventing Star Trek teleporters or whatever pet peeve your misinformed imagination has come up with this week.

NASA also pays pretty much that price to launch a Mars probe or an Earth observation satellite. My point was that 185 million dollars for a Moon shot would be cheap by today's standard. Wikipedia says that the cost of a Moon shot in 1969 was more around 375 million dollars, which equates to ~1.8 billion dollars today. By comparison, an SLS launch will cost somewhere between 500 million and 2 billion dollars. This doesn't include the cost of the payload. Each Orion CSM will cost around 700 million to 1 billion per unit, and you would have to add the cost of a lander or whatever mission module you want to bring along.

Look at our current emergencies: climate change and overpopulation. We can't even agree on a global level to reduce CO2 emissions, although it's simple common sense. There is no way we could agree to direct resources to emigrate thousands of people to Mars or the Moon in an emergency. There would be naysayers disagreeing that the asteroid problem is real, religious fruitcakes claiming that it's God's will so be it, and the rest would never agree on a solution or the path to take. Even we, as a small group on a forum, can't agree on that. But even if we could, we simply don't have the technology to divert a massive asteroid on short notice or to emigrate hundreds of people to other planets in short notice. Our best bet fir survival would be to dig deep, stockpile food and supplies, and brace for the impact. At least a few million should be able to survive, which would be enough to start all over again

This is the first I hear of such a partnership. Do you have any sources? My impression was that Skylon didn't use composites. It's supposed to be made of aluminium and titanium.

It's spelled Valkyrie, and again, the burden of proving that something works is on you, not me. I can't prove that it doesn't work because it's as much science fiction technobabble as star trek warp drives. I'm not going to waste my time explaining how fantasy and magic don't really work. This forum is supposed to be about science.

Factory was short for manufactory, which has pretty much disappeared. Manufacture litteraly means "made by hand".

Orion drive is a totally idiotic idea. Assuming you could actually build a ship that could withstand hundreds of nuclear blasts without killing everyone on board, do you have any idea how many nuke bomb pellets would be needed to propel your ship to interstellar speeds? I doubt the entire world's uranium reserves would be enough. It's an idea that goes back to the 60's when Ford was designing nuclear cars and the Russians were using nukes to dig artificial lakes. Just because someone thought it might be a good idea in those crazy days doesn't mean it still is. And your Valkyrie is science fiction. Dude, Avatar is not reality.

Sounds like Saturn and Apollo Applications Program...

There are no on-orbit serviceable parts on the JWST. Apparently they have planned to put a passive NDS on it, just in case, but there are no EVA hand rails, doors, or swappable racks like those on Hubble. Any of those provisions would have added extra mass and decreased performance, so they were omitted in the design. Also, some of the part sun shield parts might have cutting edges, protruding parts or too hot to touch, so they could be a hazard for EVA astronauts.

Some Russian missiles actually used moving weights to change their CoM for control. There is also the option of thrust vectoring.

My biggest problem with the movie were: (SPOILERS! BEWARE OF THE LION!) Obviously the orbits were all wrong. Hubble, ISS and Tiangong are all on different inclinations or altitudes. Of course, there are ascending and descending nodes where the orbits cross, but the best you could see from one spacecraft is the other spacecraft wizzing across. No way could you actually rendez-vous with it without several days of manoeuvres, plane changes, raising and lowering orbits, etc... Why was there a spare Soyuz at the ISS and a fully functional Shenzhou at Tiangong? Where did the crews go? How did they leave? But mostly, and more fundamentally, why did Clooney sacrifice himself? What magical force was pulling him away when they were stationary with the station? Why did he fly off when he detached his tether? Why was Bullock suddenly free to pull herself up as soon as he was detached? And why the heck couldn't he simply pull on the tether to bring Bullock and himself back towards the station? That whole scene was really awkward... ...but not nearly as much as Clooney's entire dialogue!