Leaving Earth's Orbit

[kags]

How many people have ever left earth's orbit? (I know what I think the answer is, but I have just read a different figure in a book!)

[Loosehead]

Strictly speaking none. But assuming you are reffering to the moon landings:

I know that 12 men have walked on the moon, some went to the moon but sat inside the modules so I think the answer is somewhere between 13 and 16

[kags]

I can get to 24 - Apollos 11 to 17 left the Earth's orbit to travel to the moon - and each had 3 astronauts on board so that's 21. Apollos 8 and 10 also orbited the moon so that's 6 more, but 3 of them (Jim Lovell, John Young and Gene Cernan) are included above, so that makes 24 in total. Apollo 7 and Apollo 10 stayed in earth's orbit, as did the Skylab astronauts and Space Shuttle Astronauts.  I read 27 yesterday (although frustratingly I can't find it again in the book!), so I wondered if I had missed someone out. I'm pretty sure the Russians stayed in Earth's Orbit.  

[Loosehead]

Fair enough Kags, I just new that 12 was the number who walked on the moon from an old Trial Pursuit question, I tried to extrapolate from that. Stricktly speaking of Course the moon orbits the Earth so they never left Earth orbit.

[kags]

ah yes - hadn't thought of that!!!

[MargeB]

Isn't 'orbit' a function of mass? The moon is large enough to be in the earth's orbit at that distance, and the astronauts on it are affected by the gravity of the moon so are in earth orbit 'with' the moon, but before they get to the moon they are out of earth's orbit? Correct me if I'm wrong.

[kempie]

kags - by your own figures there were 9 manned lunar flights each with a payload of 3 astronauts making 27 astronauts in total.

However you mention the doubling up of Lovell, Young & Cernan which brings the number of men having 'close encounters' with the Moon back down to 24.

[kags]

yes - 24 - that's what I had worked out, just wondered if there were any more I had missed.

[kempie]

Not that we know of.

http://en.wikipedia.org/wiki/List_of_lunar_astronauts

[kags]

Found the bit in the book - it's from Moondust by Andrew Smith and it says "well over 400 people have now been into space, but only 27 have left earth's orbit and been out there, all with Apollo. So not the Russians! I think he has done some double counting.  

[issy]

Surely the question which you are asking is how many have left the earth's atmosphere, that is gone into space.  No one has actually left the earth's orbit which would require travelling to the gravitational pull of another planet.

You would have to go even further to escape from our sun's orbit.

If you leave earth's orbit you are going to have a tough job getting back!

[kags]

te hee - didn't mean this to become a question about orbital mechanics. My understanding is that you can fire an object into space, and at a certain distance from the earth, the laws of orbital mechanics say that the object will fall toward the earth at the same rate the earth curves away from it, so it will stay locked in that orbit, possibly for ever, powered only by physics. In order to leave that orbit, it would be necessary to speed up sufficiently to reach an altitude where the laws no longer applied. In Apollo, that meant firing up the engines on the space ship, in order to head off to the moon. At some point, they would then become locked in orbit around the moon. So whilst they might technically still be orbitting the earth (and the sun and the centre of the solar system etc etc), they were not "locked" in earth's orbit. So how many people have done that?

[MargeB]

That's what I thought kags. Good explanation.

[Gef]

Read all of the answers and I still believe that it is none.

[kags]

Gef - why do you think it's none?

[Gef]

Kags, the furthest our astronauts have been is to the moon. The moon orbits the Earth so they are still in Earth orbit.

[kags]

yes - okay, but if you read my last answer I clarified what I was asking. I am going to write to the author and ask him.

[kags]

I have had a reply from the Author, an absolutely lovely man. The number is actually 24, the mistake was spotted too late to change in the UK hardback edition. I can sleep easy at night again.