When the first people went to space did they know about gravity in space by this point or were they totally clueless about the atmosphere (zero gravity) until they got up there?
Yes, they knew about gravity. They needed to.
I didnt mean gravity in general I meant the concept of zero gravity in space. Before man was in space how could you really know about zero gravity?
It’s not zero gravity, it’s the sensation of zero gravity from competing forced pulling you toward the earth and away from the earth at the same time. Without knowing that we could not have gone to space in the first place.
When a spacecraft orbits Earth, it is actually in Earth’s gravity well. The spacecraft is falling toward the planet, but the planet is curving away from the spacecraft at the same rate (because it’s a spheroid). This is called ‘free fall’. You can experience free fall briefly on a swing, for a longer period on a roller coaster, or a longer period in an aircraft.
See: Free fall.
Yep. An orbit is just free fall where you are high enough and fall fast enough to miss the ground.
Definitely. This is very basic physics, especially for people who build rockets.
Einstein’s theory on relativity (1907 IIRC) covers this question. People must have known about this way earlier.
Newton worked out the laws of gravity long before anyone went into space. So there were no surprises over that.
Before they actually flew any of the space missions, the Project Mercury astronauts trained for free-fall conditions in airplanes that flew zero-G trajectories (the “vomit comet”). So yeah, the astronauts and the whole space program expected zero gravity and even had some practice dealing with it.
Also, just so you know, gravity is not caused by the atmosphere. Atmosphere is like the air and stuff? And gravity pulls you down and stuff? So it’s not the same?
What medicos didn’t know were the effects of weightlessness on humans. Read Tom Wolfe’s The Right Stuff - the Mercury astronauts were NOT selected because of their engineering or piloting skills; they were selected as medical test subjects.
There were plenty of science fiction stories in the 30s and 40s that dealt with the concept of weightlessness. I think Verne even talked about it in From the Earth to the Moon.
The details and long-term physical reactions were what was learned.
Except that Verne, famously, got it wrong. His travellers only briefly experience weightlessness, around the point where they are sufficiently far from the Earth that its gravitational pull on them is cancelled by that of the Moon.
In practice any travellers who survived their capsule being shot out of a giant gun cotton cannon would be in freefall in an unpowered ballistic trajectory around the Moon and hence would be weightless the whole time.
Gravity is still pretty damn strong in the ranges the ISS and the Space Shuttle orbits. If they weren’t going so fast (so, as mentioned above, they’re continually falling around the Earth), they’d fall to the ground practically just as fast as walking off a cliff.
The Moon, which is about 240,000 miles away is kept in orbit by Earth’s gravity. No one has been past the orbit of the Moon (that is 12 men from the Apollo missions), and rest only orbit about 250 miles above the surface of the Earth.
The strength of gravity’s pull falls-off at the inverse square of your distance from the source. So, a gravity well as strong as the Earth—you’d have to go quite a distance before its pull would be nominal.
Sort of. The Moon is going just a little too fast to stay in orbit. It’s moving away from Earth at a rate of 3.78 cm (1.5 in.) per year.
Was just trying to keep things simple. 
Actually, that’s 24 men from the Apollo missions. :smack: Can’t forget the ones who made to Lunar orbit, but never walked on the surface.
Of course they knew all about gravity and the effects of the atmosphere, or lack thereof. If you are wondering about how they first dealt with these things, I would suggest looking at Gene Cernan’s autobiography. He was one of the first extra-vehicular space walkers and (as of 5/12/2015) the last human being on the moon. It isn’t great literature but it is a good read.
I’d be very surprised if the first major writer on space travel, Konstantin Tsiolkovsky, didn’t have a detailed exploration of this in the 19th century.
This is the first episode of a 1959 TV episode of the series Men into Space, in which a spaceman needs to be rescued from floating around forever after being knocked off the spaceship.