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There is an emergency on board the ISS. Astronauts can´t evacuate and they will die within five days if critical repairs are not made.

Fortunately an automated cargo spacecraft, like Cygnuss or Progress, was prepared prior to this accident and its release was scheduled in just 24 hours. A team of technicians will proceed urgently to load the cargo with tools and spare parts needed for repair.

But there is concern about whether repairs are possible if they are not made by specialized technician. The best and most specialized technician in the world, a retired astronaut who is in perfect health, flies to Tyuratam, or Guayana, or Florida, asking to be allowed to fly within the freighter equipped with an EVA suit with enough oxygen and energy to survive until rendezvous with the ISS.

Does he have chance to survive or this plan is simply suicidal?

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The biggest problem would be how to restrain the astronaut aboard the craft during the launch. Unlike a man rated spacecraft, cargo carriers have no seats, and a seat on a spacecraft needs to be capable of holding an astronaut in place during liftoff while the ship is undergoing high and variable "g" forces, lots of vibration and acoustic pummelling and weird changes in attitude as the craft rotates and tips over during the launch phase. Then the seat needs to keep the astronaut in place in zero "g" as the ship coasts in orbit, and not let him be buffeted too severely as the ship makes small burns for orbital correction and moving to dock with the ISS itself.

Since spacecraft are very high performance craft with little margin for error and payloads calculated almost to the gram, the extra weight of the seat and support mechanism would need to be compensated for by removing some of the cargo, which kind of defeats the purpose.

The other thing which makes ships "man rated" are things like life support (you will need to somehow keep the astronaut alive for 3-5 days on board the spacecraft, meaning more cargo is displaced for oxygen tanks, water and some sort of way for the guy to eat). There is also a lot of thought given to being able to separate the capsule from the rocket should some sort of disaster occur during launch, but cargo capsules typically don't have this mechanism attached (the Dragon capsule is the only exception to date, having built in rockets around the "skirt" rather than a "tractor rocket" on a detachable tower). Since we can assume the astronaut is planning to return via the Soyuz capsule attached to the ISS, we can overlook the lack of reentry protection if you are not using a Dragon capsule.

So this is one of those plans which is barely feasible even in theory, and by the time you added on all the stuff needed to get the guy in orbit, you may as well have just flown in a man rated capsule and mated it to the rocket in the first place.

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I think some preparation and modification would be necessary. An EVA suit has long suffered criticism for being more of a small space craft than a space suit, although I don't know why that would beg criticism. For you that would be a good thing. However, with a possible three day trip, this would definitely be uncomfortable for the poor astronaut. I believe they use diapers for stool. They have a urine collection bag, but that might need to be enlarged since currently EVAs only last about 9 hours. Also, because pressurizing suits to 14.7 psi (atmospheric pressure) causes them to be too stiff to be useful, they pressurize them to a lower value. That means that astronauts have to breathe pure oxygen for some time before doing an EVA in order to get nitrogen out of their blood to prevent the bends. Your astronaut would have to do something similar. I have no knowledge about food and water, but certainly he would need a larger supply of each, probably all in liquid form. So the suit might need some reasonable modifications to function properly. For oxygen he could be plugged directly into the ship or some portable unit installed in the ship.

What do you mean by "on top?" He would be on the inside of the craft, right? Otherwise, I'm pretty sure he could not handle the pressures involved during launch. The Progress has a pressurized forward module which would help.

I'm certain I am missing something, but maybe these things will help. Good luck.

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    $\begingroup$ By "on top" I meant "inside the craft, and this craft on top of the rocket". :-) $\endgroup$ – Ginasius Mar 19 '16 at 7:44
  • $\begingroup$ That's what I figured. $\endgroup$ – ozone Mar 21 '16 at 17:26

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