why astronauts on return from a space journey are unable to walk?
969840
Being in a weightless condition means the leg muscles atrophy from non-use
980237
Since its a manned flight, the space craft being heavier, it would take at least eight months or more. However, like correctly pointed out by Christoph... N, it would be a very painful ride for the space passenger. The radiations and the athropy of the muscles & bones would cause a lot of discomfort.
150431
in space there are negative effects such as loss of bone mass and gradual weakness due to the absence of gravity.
261571
The astronaut actually has to pass his own gas to stay warm in space :).. \nok seriously To work in the open cargo bay of the space shuttle or in space, astronauts wear the shuttle extravehicular mobility unit (EMU) spacesuit and they are kept warm by their own bodies heat because of the well insulation and design of the EMU
72063
They already do. Do you mean, inter-planetary flights? And if so, how far away? Pluto? Nuh-uh. Mars? Not necessarily a bad idea. It all depends on how far away the mission crew is to be sent, and how long the duration of the journey is to be. If the crew were to find themselves in an emergency, they would of course have to be more resilient and capable of quick thinking because Houston would not be of any help to them.
1135793
Due to the lack of an atmosphere in space, sound cannot travel.  A rattlesnake's familiar tail shaking will not be heard in the vacuum of space.
116745
I used to be suspiscious.  But then I found that in preparation for the moon walk, the astronauts had to be ready to step in at least 3 feet of space dust, based on evolutionary models that had the moon sitting there for 3-4 billion years collecting space dust.  When they got there, however, there were only a few inches of dust.  If they had staged it, they would have likely put 3 feet of dirt to make it look real.  But they were surprised when they landed only to find a few inches.  Might say something about evolutionary theory, hmmmm...
1020818
Not unless they are incapable of walking.
294010
One big adjustment is to once again get used to an environment that has gravity.  In the gravity free environment of space movement is unhindered by gravity.  Back on earth muscles have to readjust.
399830
They asked astronauts questions like this: "what if you had an oxygen leak and only had 10 minutes of air.  What would you do?"  The answer is "spend the next 10 minutes trying to find and fix the leak".\n\nSame thing for this question:  Try and survive any way you could.
879679
The camera was mounted on the leg of the lunar lander.\n\n1) Twelve 12 American astronauts have walked on the moon.\n\nApollo 11: Neil Armstrong & Buzz Aldrin\nApollo 12: Pete Conrad & Alan Bean\nApollo 13: << failed to land on the moon >>\nApollo 14: Alan Shepard & Edgar (Ed) Mitchell\nApollo 15: David Scott & James Irwin\nApollo 16: John Young & Charles Duke\nApollo 17: Eugene (Gene) Cernan & Harrison Schmidt\n\n\n2) Why haven't we been back?  \n\na) American astronauts visited the moon on six occasions.\n\nb) The "moon race" was an extension of the cold war. It was mostly about national prestige. We got there first and achieved our primary objective. There was some good science: surveys, measurements, sample collection. But it was mostly about being there first. Once we achieved our primary objective, there was no political will to go back. There still isn't.  Perhaps, if we discover He3 or something else valuable, there will be.\n\nc) I used to travel to Crested Butte, Colorado every year to ski. Because I don't go anymore, does it mean that I never went?\n\n\n3) What about the Van Allen radiation belts?  Wouldn't it have killed the astronauts?\n\nThe existence of the Van Allen radiation belts postulated in the 1940s by Nicholas Christofilos.  Their existence was confirmed in *1958* by the Explorer I satellite launched by the USA. \n\nThe radiation in the Van Allen radiation belts is not particularly strong.  You would have to hang out there for a week or so in order to get radiation sickness.  And, because the radiation is not particularly strong, a few millimeters of metal is all that is required for protection.  "An object satellite shielded by 3 mm of aluminum will receive about 2500 rem (25 Sv) per *year*."\n\n"In practice, Apollo astronauts who travelled to the moon spent very little time in the belts and received a harmless dose. [6]. Nevertheless NASA deliberately timed Apollo launches, and used lunar transfer orbits that only skirted the edge of the belt over the equator to minimise the radiation."  When the astronauts returned to Earth, their dosimeters showed that they had received about as much radiation as a couple of medical X-rays.\n\n\n4) The U.S. government scammed everyone?  \n\nIn 1972, there was a politically motivated burglary of a hotel room in the Watergate Hotel in Washington, D.C. There were only about six or eight people who knew about it. However, those people, including Richard M. Nixon, the President of the United States, failed to keep that burglary a secret. It exploded into a scandal that drove the President and a number of others from office.\n\nIf six or eight people couldn't keep a hotel room burglary a secret, then how could literally thousands of people could have kept their mouths shut about six faked moon landings? Not just one moon landing, but six of them!\n\n\n5) What about the USSR?  \n\nEven if NASA and other government agencies could have faked the six moon landings well enough to fool the general public, they could NOT have fooled the space agency or military intelligence types in the USSR. The Soviets were just dying to beat us. If the landings were faked, the Soviets would have re-engineered their N-1 booster and landed on the moon just to prove what liars Americans are. Why didn't they? Because the landings were real and the Soviets knew it.\n\n\n6) Why does the flag shake?  Where are the stars?\n\nTake a look at the first two websites listed below.  They deal well with all of the technical questions.\n\n\n7) Finally, please tell us what you would accept as definitive evidence that the six moon landings were real. Is there anything?
219948
walking requires one foot to be on the ground at all times... running- both feet are off.... so, the instant there is that lapse where both feet aren't on the ground
735960
There have been several African-American astronauts\n\nhttp://ask.yahoo.com/20020218.html
320348
Deep ocean travel requires two things:\nProtection from the enormous pressure\nAdequate supply of oxygen and breathing gas for the safe return to the surface.\n\nAs we dive deeper, our bodies are subjected to the increasing water pressure.  This is especially so if we dive only to depths of less than 100 meters.  As we dive deeper, our bodies are subjected to greater pressure.  Our blood absorbs MORE gas (namely nitrogen gas); as we return to the surface, the increased amount of nitrogen gas in the bloodstream begins to leave the bloodstream.\n\nIf divers return to the surface too fast, the nitrogen gas will bubble out too fast causing a painful and possibly fatal condition called "The Bends".  So, divers must "acclimate" to sea level pressure slowly.\n\nDivers who dive very deep must remain inside pressure chambers in which the air pressure is slowly reduced to sea level pressure, gently allowing the (bloodstream's) absorbed nitrogen gas to escape safely.
299767
YES. The atmosphere is so thin you can't breathe. When the first astronaut, Alan Shepard, rode Freedom 7 in suborbital flight we sure thought we were going into space. All the hazards of deep space were experienced on that flight.
52518
Although the astronauts can comfortable work in any orientation, the shuttle is generally designed as if the roof were "up" and the wheels were "down".  Of course, the whole cockpit has to be designed like this since the astronauts are in it during landing when there definitely is a diference between "up" and "down".  But if you look closely at the pictures in the links below, you will see that in the work area, most visual cues (like signs and labels) and the workstations are also all oriented in this way.  \nThis means that the astronauts GENERALLY work with the roof being at their heads, which thiers brains will interpert as being "up".\n\nInterestingly, the space shuttle actually flies upside down relative to Earth (the roof and open shuttle bay is usually facing earth).  But even with the windows, the astronauts don't feel like they are upside down- to them, the Earth is just above their heads.\n\nhttp://www.nasa.gov/images/content/124678main_s114e7127.jpg\nhttp://www.nasa.gov/images/content/124681main_s114e7129.jpg\nhttp://spaceflight.nasa.gov/gallery/images/shuttle/sts-114/lores/s114e7111.jpg\nhttp://www.nasa.gov/images/content/124669main_s114e7012.jpg\nhttp://www.nasa.gov/images/content/124666main_s114e7001.jpg\n\nAbout your Jan 4 edits:\nAs I mentioned above, the shuttle generally orbits with the "top" (or "roof" or "bay doors") pointed towards earth.  However, if two shuttles were to meet in space, they would be oriented in whatever manner was appropriate for the manuver they were attempting (docking, payload transfer, etc.)
122974
"bred2bbroken" covered the question well.  I add one interesting tidbit to his answer.  The sensors that tell your body that you are thirsty are in your head.  With all that blood and bodily fluids moving away from your feet and towards your head (due to the absence of gravity), you do not feel thirsty.  This causes a problem during reentry.  Suddenly, you are severely dehydrated.  This can lead to lapses in judgement, etc.  Astronauts, therefore, drink a gallon of water during their final orbit.  If reentry has to be delayed, due to adverse weather conditions or whatever, then they have to orbit again.  Guess where all that water goes?  :)  So, they make one pass around, which takes a little over an hour, and then they have to chug a gallon of water again!  :)