So, you want to take a short trip into space? Seems easy enough – hop in your rocket, aim it at space and lift off, right? If you want to survive, it will take a little more planning than that. Luckily, we're here to help.
Space is inhospitable to humans. It's too cold, has nothing for us to breathe, and requires high velocity to reach and maintain orbit. The worst part is probably the return trip. Re-entry will subject your spaceship (and you) to extremes of temperature and force that are difficult to overcome. Before you get started on your own space flight, go through our handy checklist to make sure you've got the bare essentials.
Capsule. This is your tiny chariot of the gods, the throne from which you'll survey the heavens from orbit. In reality, it will be a cramped canister that will be, in turn, too cold and too hot. If you want to really trim your budget, you can make the whole thing one giant sphere of aluminium alloy. That's how Yuri Gagarin, the first person in space, did it.
Insulation. Space is cold. To be more accurate, space has no temperature at all, since it's a vacuum. The amount of insulation you need depends on how long you want to hang out in space. The minimum is some kind of thermal blanket lining the inside of your capsule. This will keep you from freezing while in space and also mitigate some of the heat of re-entry.
Oxygen. The cheapest method uses potassium superoxide (KO2), which, through a chemical reaction removes carbon dioxide and adds oxygen to the capsule's atmosphere. If your capsule is not airtight (many American space capsules were designed to allow slow, steady leakage), you'll need pressurized air to maintain pressure and breathable atmosphere. Some emergency pressurized oxygen bottles are probably a good idea – 10kg of oxygen will be enough to get you through a short emergency. Just be careful around the pure oxygen.
Rocket. Now that you've got a capsule with a reasonable chance of supporting human life, ever so briefly, in space, you have to get it to space. Mount the capsule on top of a large rocket. If you want to fly old-school, you'll need roughly 136,000kg of hydrazine/dinitrogen tetroxide rocket fuel, which is scary stuff, but at least it can be safely stored at normal temperatures. If you're being safety conscious, modern solid fuel like the space shuttle's Ammonium Perchlorate Composite Propellant is a better choice.
Control systems. Your capsule may have its own on-board control rockets, or be temporarily attached to a control module. You'll need a way to orient the craft for re-entry and rockets to fire at the right time to send it into re-entry. You can use pre-programmed on-board computers, let the ground crew handle it, or put it into the pilot's hands. Don't scrimp here. Too steep of a re-entry angle and you'll burn up. To shallow and you'll bounce off the atmosphere and careen off into space. "Your circuit's dead, there's something wrong…"
Re-entry. When you re-enter the atmosphere, your capsule will be moving at around Mach 25. The "bow" of your capsule creates a shockwave of super compressed gases, and that compression heats them up tremendously, to over 2500C. You might assume a streamlined shape would be best, but it turns out that a blunt, wide object pushes the shockwave ahead of itself, keeping the heated gases a little farther away. That's why Vostok capsules were spherical (they were wide and blunt from any re-entry angle) and Gemini and Apollo capsules were cone-shaped (they re-entered wide end first). Even so, the capsule is going to experience a lot of heat. The cheapest heat shield for a one-time mission is ablative, usually made of beryllium or a metal alloy. The shield gradually chars and burns away, sacrificing itself so that you can reach the Earth. If you've got the R&D budget, ceramics work very well and have better insulating properties. Finally, don't forget a sturdy internal frame and well-anchored seat belts. You'll be pulling 3 Gs or more (Gagarin reportedly remained conscious under 8 Gs of deceleration).
Landing. The parachute/sea touchdown method seemed to work pretty reliably for the Americans. The Russians always had trouble with their landings – Gagarin's capsule left a crater, though luckily he'd ejected and came down with his own parachute. Don't overlook this aspect. It would be a shame to mess things up at this point in the mission.
Plan B. Don't expect everything to go smoothly. Somewhere along the way, there will be a problem or a unforeseen circumstance. Carry extra food, water and oxygen. Install a backup computer system (they're so small and light these days). Make sure the pilot is trained to engineer solutions or take over control systems if necessary. And fold your own parachute.
Davis, Jeffrey R., et al. Fundamentals of Aerospace Medicine. Lippincott Williams & Wilkins, 2008.
NASA. "Gemini 9A."
Sotheby's. "Vostok program."