# body burning up on entering earth's atmosphere

Would a human body, wearing no special safety clothing, burn up completely upon re-entry into earth’s atmosphere, after being jettisoned toward earth from a spacecraft in orbit?

In view of the amount of energy that would have to be dissipated before any remains reached the surface, I think the answer must be yes.

Various Googling suggests the Shuttle sees a temperature of around 1500 C for 15 to 20 minutes. That ought to get the job done.

Probably yes if you planned it for that purpose but the Colombia shuttle disaster proved that recognizable body parts could just fall from space after the break-up of the spacecraft itself. There were many of them and their protective gear wasn’t that strong. Even parts that weren’t covered fell to earth severely burned but still mostly intact.

Right, but that’s a different story from what’s specified in the OP: body only, no spacecraft.

More significant to me - Columbia broke up somewhere around 39 miles up, as far as I can quickly tell. That’s a far cry from orbit, and meant that the people who were in Columbia at the time of the disaster weren’t subject to the initial fall through the upper atmosphere themselves.

If rocks burn up in the atmosphere, I’d expect bodies to, as well.

Wouldn’t it be a matter of velocity? Joe Kittinger sure didn’t burn up, although he was only about 20 miles up.

Since OP indicates the craft was in orbit, that would mean a pretty significant starting velocity, no?

Also, not only was Columbia at a fraction of its initial orbital height, it had (i’d expect) “burned” off a significant/majority? of its horizontal velocity component. Given that total energy is a function of velocity squared, you now have a small fraction of energy to get rid of as compared to starting from an orbit.

If you just dropped someone from orbit (assuming they were not orbiting at all) then I do not think they would burn up much. As noted Kittenger didn’t have that problem although in the much thinner atmosphere above him I am not sure what the terminal velocity would be.

If you are in orbit then yeah, you are moving pretty fast. IIRC the Space Shuttle orbits at something like 5 miles/second. If you hit the atmosphere moving about that fast you are going to burn up if unprotected.

Rocks burn up due to compressive heating, and rocky (as opposed to metallic iron) meteoroids break up from the forces involved more often than not. I’d expect similar forces exerted on a human body to tear it to shreds; those shreds being relatively light are going to slow down very fast. So, I’d expect some significant charring, but also fairly good-sized fragments to remain intact and land on the ground.

Note that a large percentage of the rocks entering our atmosphere are going considerably faster than LEO velocity.

In fact, most meteors enter with an initial velocity approaching or exceeding the Earth’s orbital speed (~29.7 km/s), and even Near Earth Objects that are nominally in Earth’s orbit and are perturbed into intercept are moving at around Earth escape speed (11.2 km/s), which is significantly higher than orbital speed at LEO. Also, most aerodynamic heating from ram pressure is going to occur in the upper layers of the upper stratosphere; by the time you hit anything one could reasonably discern as an atmosphere a blunt, low beta body like, er, a body, is going to be moving so slow that convective cooling will vastly override any pressure-based heating. I would tend to agree with Q.E.D.; that the aerodynamic forces may pull extremities off or the torso apart, and the heating and evaporation from the reentry environment will tend to weaken the body structure, I would expect major parts to survive reentry with external charring and desiccation plus impact trauma at surface level terminal velcoity (200-350 kph, depending on size of part).

It is at least conceptually possible to provide reentry for a live person with minimal protection. See the MOOSE personal emergency reentry system. As long as the system remains aerodynamically stable in the arse-down position and doesn’t turtle, there is no reason why this concept couldn’t work.

Stranger

Hmm. If I dropped a feather from orbit, it’s low density/low mass means that air resistance will slow it down below the threshold required to cause it to combust, wouldn’t it?

Rocky or metallic objects (dense) retain higher velocities for longer, so heat up more.

The question, than, is the human body going to be slowed down enough, or is it dense enough to retain speed.

(Or am I on the wrong track?)

Was that the one with Juan Valdez serving as captain?

FWIW, various Googling suggests a human body has about 5 times the average density of the Space Shuttle during re-entry.

Sounds like I might be on the wrong track then, thanks.

You can’t look at bulk density for the purpose of exterior ballistics, unless you assume that the horse is a sphere to make the math easier. You have to look at the sectional density and form factor to derive the ballistic coefficient, which is the mass over the section area divided by the form drag coefficient, or the sectional density divided by the form factor coefficient. This will give the a roughly inverse linear relationship to deceleration for high speeds. In addition, although you can calculate bulk energy loss from this, local heating due to leading edge features which cause stagnation can be much higher than the overall thermal environment the vehicle will see, hence why the Shuttle has high temperature carbon-carbon leading edges and thermal tiles on the underside, but relatively less insulating thermal blankets on the top sides of the wings and on the more protected parts of the fuselage. The aft parts of the Orbiter topside are actually cool enough to sit on during reentry if you don’t mind a shear force that would take your head clean off.

All of this assumes a stable orientation in flight, which the human body obviously wouldn’t enjoy. Something floppy like a body will tumble and flail in flight, which changes the beta and can serve to dissipate energy by converting momentum into lift and losses due to turbulent drag. The Shuttle, on the other hand, comes down in an automatically controlled flight path that maintains a high drag orientation and performs a series of energy wasting maneuvers to in the upper atmosphere before it hits the thicker bits of atmo where it glides in.

Stranger

Depends - if it gets going fast before it hits significant amounts of atmosphere, I think it could burn up.

I’m a bit confused by this. It sounds as if you’re saying that a body may convert its energy to turbulent drag, while on the other hand the Shuttle does much the same thing.