Space Diving

Red Bull Stratos

Like skydiving, space diving refers to the act of jumping from a plane, balloon, or spacecraft in outer space and falling to Earth’s atmosphere before parachuting to a landing. Depending on one’s definition of ‘space,’ the only historical case of a human intentionally space diving from the stratosphere is Joseph Kittinger, who jumped from a helium balloon at the height of 100,000 feet (approximately 30 kilometers).

Higher jumps from mesosphere or thermosphere have yet to be successfully performed, though Orbital Outfitters is working to create a suit that will enable safe space diving. Space diving from beyond the stratosphere has been imagined in various fictional contexts.

Robert Heinlein, the author of ‘Starship Troopers’ and a former spacesuit designer, conceived of a (fictional) reentry system involving multiple ablative shells and parachutes. These requirements would be somewhat eased when entering the atmosphere from a simple drop, where the heat of reentry would be considerably less than that of reentering from orbit. Parachutes would require increased strength to slow the higher weights associated with the added equipment.

There are several technical requirements and challenges to the possibility of space jumping. The space diver suit would have to protect against hostile temperatures, pressures, and lack of oxygen. At the heights involved, low pressure would cause decompression sickness within the space diver. This would turn the blood to gas and would be fatal. Furthermore, depending on the weight of the diver, the reentry suit would likely have to be armored to survive the heat of reentry. While there is no ‘fire layer’ of atmosphere, the speed of orbit is in the thousands of kilometers per hour. To go from this speed into the atmosphere would cause friction on the air, and could cause the diver to heat up to 400+ degrees Fahrenheit.

Gravity is also a challenge. As the diver presses through the thin atmosphere to the thicker air below, he could slow at such rates that he experiences negative G-forces from 2-8, possibly contributing to blackouts or other pressure-related complications. NASA is known to have investigated the concept in case of an emergency situation on the shuttle where alternative methods of reentry are not available — however, such planning has not moved beyond the conceptual stage given the high energies involved in reentry from orbital speeds.

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