The space elevator is to send materials out of geo. orbit, what do we really need to send to space?
367942
Let's take a hypothetical example:\n\nYou start a mining company. You are trying to mine asteroids for ore, at which point you send the ore back to earth and drop it to the ground. However, ships, spare parts, electronics, etc, are all built on Earth.\n\nThe point of a space elevator, is that you would be able to boost stuff to space at a vastly lower cost than trying to use propellant to beat the Earth's gravity. This would allow you to take advantage of all the natural resources that are sitting around in the solar system - He3 in the gas giants (for nuclear fusion, if we figure it out),  ores from asteroids, finished goods (from orbital factories operating in microgravity), etc.\n\nOnce you resolve the expenses of boosting stuff to orbit, you would be able to justify an intrasolar economy and eventually colonization of the Moon, Mars, Pluto, asteroids, and possibly moons like Phobos, Deimos, Titan, and Charon.
1159810
1) Practice.  If we are to go anywhere else, we need to learn how to handle the unfriendly environment.\n\n2) Unknown intangibles.  The original space program needed small, lightweight computers to take with them in space.  Now everyone reading this is using a small, lightweight computer, rather than using a terminal to tie into a large mainframe.\n\nA return to space, for long-duration missions, could (repeat, COULD) yield new recycling methods, or improved energy-efficiency, or localized energy production.\n\nOr it may produce nothing.  It's a gamble.  But compared to other gambles that we routinely make (research into more effective weapons, that may never be needed to be used, for example), it's a comparatively inexpensive one.
171362
A lot. At least 2000. Plus lots more space junk, old boosters, bits of metal, etc.
685026
u also need to create a biosphere,,self contained sealed enviroment that has oxygen producing plants and also plants for food,and a filtering system for water. and a waste mangement system all self contained. and a communications system back to earth.
1142221
because the cost of building robots and sending them out to space to mine these asteriods, then transporting the ore back to earth is more than the ore itself. We will begin to harvest space junk when space travel becomes cheaper.
394388
Speed/velocity, isn't actually what's needed.  It's acceleration.\n\nWhether it's a huge acceleration at the start and a gradual slowdown into orbit (imagine a gun), or a slow acceleration throughout the trip, the result is the same.  \n\nThe space shuttle uses a combination of the above - a steady (fast) acceleration at the beginning, then a coast into orbit.\n\nWhat is needed is that the total force pushing you up is greater than the total force pulling you down.
1059573
Sure if you mean a robotic space craft. We could even send a human, if we don't care that he would die shortly. As far as sending a craft with a living human, we don't have that technology within a reasonable price range.
889751
Possible, yes.  Likely, no.  We know the orbits of the satellites we put up pretty well.\n\nHowever, there IS a lot of junk orbiting the Earth - pieces of spacecraft, nuts, bolts, etc - and they are orbiting fast.  Being hit by a fast-moving piece of space trash is something they have to keep in mind and try to account for when building shuttles.
625832
I assume this question involves using common sugar (sucrose) are the fuel.\n\nThe answer would depend on how you are extracting the energy out of the sugar as well as just how large of a mass (rocket + ...) you want to move to the moon.\nYour question is far too vague (and meaningless) without A LOT more details.
762426
Absolutely. In orbit, the space shuttle crew tests (although there is no actual need to use) the hydraulic system, and the system is actually used in both the ascent and descent phases to move the aerosurfaces.
313099
Well, it's literally "rocket science."  Gravity is the worst problem, probably.  It takes a huge amount of rocket fuel to get even a small object into space, let alone people and all the things they have to carry with them. (Imagine how exhausting it would be climbing straight up a 50-mile-high cliff.  Now imagine doing it without anything to hold onto!)  So once you get something up there, there's not much fuel left to keep accelerating.  Every little ounce has to be counted and allowed for in order to get a rocket up into orbit.\n\nBesides, in space everything is relative.  Spaceships and probes actually travel quite fast -- thousands of miles an hour -- but the places we're going to are MILLIONS of miles away.  The Cassini probe to Jupiter traveled nearly two billion miles to get there!\n\nFuel is just one of many problems that have to be dealt with in space travel.  In space, there is NOTHING at all.  No food, no water, no electricity, no heat, no air, no gravity.  Compared to space, walking across the Sahara Desert would be a fun hike.\n\nThere are so many things that you might never think of.  For instance, when the very first astronauts went into space, nobody knew what would happen to their eyes.  It was possible that in zero gravity their eyeballs would lose shape, and they would be blind!  Luckily, that didn't happen, but at the time nobody knew for sure.  Because of that and many other dangers, astronauts are very brave people.
431855
Hi there!  I'm a physics and astronomy student, so, while I'm not the authority on the subject, I can tell you what my current understanding is:\n\nIt really all comes down to cost in my opinion.  We aren't sending astronauts to Mars primarily because it would cost a lot to get them there with current technologies and it would still take a while for the trip (it took about 7 months for the Mars rovers to get there).\n\nSome people also think it is unsafe because we haven't sent humans out nearly that far yet.  Messages would also take at least 8 minuets to get a response (I think Mars is about 4 light minuets away so it would take as long to transmit a signal to Earth and just as long for the response to get back).  That's kind of a pain but not a big problem in my mind.\n\nAs for sending probes further out, this is indirectly related to cost.  We are still only able to move so fast.  You can blame this on reduced funding for NASA if you like (or closed minded scientists perhaps).  \n\nWe have sent a few probes out to explore the outer planets of our own solar system but we can't expect to be exploring other stars and solar systems anytime soon because even the next closest star system is about 4.3 light years away.  If we could travel at the speed of light (which we definitely could not with current technology) it would take 4.3 years to get there.  (Using the relationship for Mars from earlier I'd guess that this means it would take oh...162,540 years (really rough estimate assuming I did the math correctly) with our current abilities, so sending humans would be silly since we rarely make it past 100).  This is connected to funding because, in theory, if we had more money we could come up with and actually use better ideas for space exploration, including faster means of travel.\n\nFinally, we can explore "visually".  We can collect different types of light (like visual light, infrared, x-ray, and ultra violet) and learn a lot about our universe that way.  Most of what we know about our universe comes from local collection and interpretation of this (like with Hubble).  This field is progressing at a reasonable rate as we developer better equipment for viewing very distant things in great detail.  It could also benefit from increased funding though.\n\nIn retrospect, I suppose that money might be the root of the issue, but until we figure out how to jet through space more quickly, so is time.
1034887
Mass transfer.\n\nThe mechanism is one by Newton, not Einstein, and it is Newton's 3rd law.\n\nThis mechanism is the whole action-reaction thing and applied to the rocket is simply; as the fuel is burned and exhaust expelled the expulsion of the exhaust mass is what propels the rocket in the opposite direction.
847011
You would need to provide vast amounts of resources provided to earth from space and travel into space. People fight and hate for the limited resources  and wealth available.
1015902
It all comes down to how big your planet is and how far you want to move it.  You need a way to exert a force on the planet for a long enough time to get it to produce enough of a velocity change to get into the other orbit.\n\nTheoretically it is simple.  Practically it is impossible.  There just aren't sources of propulsion powerful enough to move something as massive as an average planet a substantial distance.
924904
Firstly our wastes contains many substances like several kinds of elements for e magnesium, iron, cobalt, etc.. If we send them into space, we will lose the possibility to recycle the wastes and reuse the elements or compounds in them to manufacture other things. However if we want to get rid of them by space, this costs a whole lot of money since for sending 1 g of waste, about nearly hundred times the amount of energy needed to create that waste will be lost to propel the waste into space. So it would be illogical to do that since we would be wasting our precious energy sources, our money and also polluting our earth more by the burning of fuels to propel the rockets into space.
60821
We have been able to navigate and land unmanned craft from the Earth to Mars, however it is a lot different than traveling the 240,000 mile to the moon.  Mars is millions of miles away from Earth.  We just last week launched an unmanned craft to Pluto, it is the fastest traveling spacecraft to date and it is going to travel 36,000 miles an hour and take 9 years to get there.  The amount of dedication and logistics to send a manned spacecraft to Mars sucessfully is probably the biggest question.  I believe when we can get the traveling time down we will see manned missions to Mars, it won't be money that keeps us from going what's another trillion dollars in National Debt amoung friends anyway?