# Surviving Re-entry in only a space suit

Because who needs a space craft?

Picture this:
While performing a routine spacewalk, outside your small, 1- man space pod, a fault in the propulsion system controls causes the pod to explode, launching you into a low orbit of the Earth.

Now with a limited air supply, and only your own space suit & MMU (Manned Manuvering Unit) at your disposal, you are tasked with re-entering Earth's atmosphere, in a survivable manner. (Please note that chance of survival does not need to be 100%).

The Question:
Is it scientifically possible to survive re-entry in this manner, and if so how? If not, and if it would be possible if the scenario were to be modified, please describe how it could be modified in order to make it possible.

Note: Your MMU does not need to be of the modern NASA variety. The story is set a short time in the future, so the design can be slightly more advanced (but still within reason for an MMU).

Edit: Originally, I had planned for the MMU to provide a wireless transceiver (allowing the astronaut to calculate his re-entry angle based on GPS signals?), a set of manuvering thrusters (set his re-entry vector & slow him down to prevent a crash - if possible), and possibly the material needed to construct a rudimentary heat-shield (if such material would feasibly be used in construction of an MMU).

• Would you be orbiting the Earth six or seven km / second? If so, no. – Mikey Jan 23 '16 at 3:20
• You can be orbiting at any feasible speed. Plus the thrusters on your MMU could be used to alter your speed (to a realistic extent) if necessary. – Chef Cyanide Jan 23 '16 at 3:30
• They might as well say, "You're gonna die Jeff". – Xandar The Zenon Jan 23 '16 at 3:37
• Check out this: en.wikipedia.org/wiki/MOOSE – AMACB Jan 23 '16 at 3:55
• I assumed your MMU to be something like a near-future EVA setup, in which case, absolutely not. Further to this, I would expect your destroyed space pod would have the only chance of things like a parachute? I'm not trying to be contrary, because I think it's a good question (+1), it just seems like a dead end to me. The answers will be good here though. Maybe define what's included with the MMU that's not included with the 1-Man Space Pod? – Mikey Jan 23 '16 at 5:42

There are many problems to overcome:

According to NASA, most meteors of a radius of 80 feet burn up in the atmosphere so that they cause little to no damage. So, we need to somehow cool off our poor guy so that he isn't a pile of ashes by the time he hits (or floats, if he was ashes) to the ground. Add a very potent coolant system or heat shield.

Now that we've solved burning up, we still have to consider landing. Terminal velocity at sea-level for an upright human is about 200 mph. Most meteors burn up around 30 miles, so our friend would have to decelerate in a "mere" 30 miles, either requiring a reverse propulsion system to boost him upward, or a parachute. The former would also require some kind of stabilization system, such as gyroscopes, to avoid flipping over. The problem with a upward thrust is that gravity will push down when you are not at terminal velocity, so you would have to supply a continuous thrust of around 9.9 m/s^2 for about 10 minutes to slow him down to land safely (which is impractical), so you would need a parachute. To be safe, we also include a upward-accelerating jetpack to ensure a safe landing.

All in all, your chances for survival are fairly slim, but it could be possible to survive such a fall.

• Thank you for such a practical analysis of the problem (+1). Out of curiosity, do you think it would be feasible for our astronaut to re-configure his MMU in order to provide the thrust which you mentioned? – Chef Cyanide Jan 24 '16 at 14:29
• Unlikely if he is floating around in space. Even if he was inside a space station, I doubt he could figure out how to even if it was possible. – AMACB Jan 24 '16 at 16:03
• We can dispense with the parachute. He's got quite a range of places to land and presumably good guidance as to the deorbit burn and where to aim. His target should be a place that lacks things sticking up and has just received a huge snowfall. Extremely dangerous but potentially survivable. – Loren Pechtel Jan 24 '16 at 17:48
• Pretty good summary of the issues, but you missed the first one: getting into re-entry in the first place. Unless the hapless voyager can alter his orbit enough to re-enter, he will just orbit forever. Not every orbit that intersects the upper atmosphere is a re-entry: if you come in too shallow, the atmospheric shock just bounces you back up! – Securiger Nov 14 '18 at 11:37
• (And the delta V needed for this manoeuvre is vastly more than real world EVA kits can provide: for example, the MMU does a maximum of 23.4 m/s. when you need km/s.) – Securiger Nov 14 '18 at 11:46

If this sort of scenario was considered likely, the MMU might incorporate a "ballute".

This is a low mass substitute for a reentry heat shield, and has the added bonus of being an air bag for your final landing. Real life use includes being used to retard bombs (so the bomber can escape the blast) and this has been proposed for real life space missions. The movie 2010 has the Russian spacecraft using a ballet to aerobrake in the orbit of Jupiter, so the technique is versatile.

Now this might not be a common thing to add to an MMU, since while lighter than a heat shield, the mass of the fabric and gas bottles to inflate the Ballute will still be considerable, and make manoeuvring in space slow and unwieldy (you will also require far more fuel for your MMU to work). It would be like suggesting you always carry a parachute and a backpack full of survival gear for both desert and arctic conditions, on the off chance you fall out of an airplane or window.

For your scenario, if the construction shack can't send a rescue pod out quickly enough to pick up the unfortunate astronaut, they might be able to launch a "reentry pack" with prepackaged ballute, inflation gear, extra oxygen, survival kit and a powerful solid fuel rocket motor. It intercepts the astronaut, who rapidly straps it on (or the robotic arms on the device grab him and pull him aboard), then it orients itself, the solid fuel motor fires to begin reentry and the ballet inflates. For simplicity, the device might actually be designed to land on water so the ballute becomes an improvised life raft as well (using it as an airy bag on land might bounce you face first into the desert floor....).

Happy landings

• While still not quite as epic a solution as I had originally been hoping for, your solution is both realistic and practical (assuming I can find a way for our unfortunate astronaut to acquire one of these ballute systems). I will certainly consider it if I can't find a way to achieve re-entry using the materials that are already in the astronaut's possession (+1). Thank you very much! – Chef Cyanide Jan 24 '16 at 14:25
• No problem. Don't stand too close to windows, though ;-) – Thucydides Jan 25 '16 at 1:55