burn-up on re-entry

[PLIVELY34]

if i was out in space wearing only a space suit and decided to return to the earth's surface without the aid of a space shuttle or re-entry capsule, what speed what i have to be going not to burn up to dust. i always have thought to myself if i re-entered that earth s atmosphere at say 3 miles per hour could you survive re-entry. i always thought it was the friction with the atmosphere at speed that caused objects to burn up. any one know the answer to this one as i don't fancy testing it in the field.

[Teddio]

Assuming you are in low Earth orbit ,your speed would be about 17600mph. You would have to slow down to around 17000mph to lose enough height to enter the Earth's atmosphere. You would burn up!
If you were motionless, say 200 miles above the Earth's surface, you would have to continuously burn a rocket motor to produce a thrust force equal to your weight. To achieve a re-entry speed of 3mph would mean using a rocket producing a thrust equivalent to your body weight for several hours. Not a viable option.

[jake-the-peg]

As Teddio says the nub of the problem is whether you are in orbit. To achieve an orbit you have to be going at quite a speed and you have to loose that to re-enter.

If you're sub-orbital it's not such a problem. This is why the Virgin Galactic commercial passenger spaceflights will be sub-orbital.

They intend to use a craft based on 'spaceshipone' which won the X prize for the first commercial reusable space flights.

However even this reached 600�C (about 1000�C less than the shuttle) so you'd be unlikely to survive in just a space suit free falling in this way - let's say medium-rare as opposed to well-done - and the fuel you'd need to slow your decent would be considerable.

[heathfield]

At Mach 2.0, around 1,350 mph, Concorde's nose would heat up to approximately 127� Centigrade ( 260� Fahrenheit). That's considerably hotter than boiling water, so you might want to re-enter a tad slower than this.

[dundurn]

You might find it interesting to read up on Joe Kittinger. He was a researcher into high altitude ejection from jet aircraft and tested a new parachute desihg by going up, initially to around 70,000 ft and finally to over 100,000 feet , suspended under a balloon. Then he stepped off! Not quite out in space, but as near as anyone would want to get.

[PLIVELY34]

thanks for all the answers. clears a few things up