We’ve still got a few technical kinks to work out before we can parachute down to Earth from the cosmos.
In 2014, Alan Eustace, then the senior vice president of knowledge at Google, dropped from a hot-air balloon floating 135,899 feet above Earth’s surface. During the four minute and 27 second plummet, the tech mogul reached speeds of over 800 miles per hour and shattered Red Bull stuntman Felix Baumgartner’s previous skydiving record, established just two years earlier.
Since U.S. Air Force Capt. Joe Kittinger’s famous free-fall from 102,800 feet above Earth’s surface in 1960, adrenaline junkies have sought higher and higher altitudes from which to jump, inching ever closer to the Kármán line, or the boundary between our atmosphere and space. So far, neither Eustace, Baumgartner, nor anyone else who has careened down from the heavens has made it anywhere near the boundary, which lies roughly 62 miles above Earth’s surface, or 327,360 feet. So what would it actually take to skydive from space?
The Edge of Space
First, you have to get there. In the past, these high-altitude skydivers have used specialized hot air balloons to lift them into the stratosphere, the second layer of Earth’s atmosphere. But balloons can only go so high (roughly 135,000 feet) before the air becomes too thin for them to maintain their altitude. Reaching greater heights requires rocket-powered flight—a challenging feat because the diver’s bailout would need to be timed for when the spacecraft reaches its apogee, the point in its orbit when it is farthest from Earth.
A Specialized Suit
The pressurized spacesuits astronauts wear act as personal spaceships, with everything the astronaut needs to survive in the event of an emergency. A space diver’s suit “would have to be a very, very rugged spacesuit,” says Erik Seedhouse, Ph.D., an assistant professor at Embry-Riddle Aeronautical University in Daytona Beach, Florida.
For starters, it would likely require its own propulsion capability, Seedhouse says, in order to properly orient the diver so they don’t begin to tumble out of control—something that could cause them to pass out or that could tear off an arm or leg. Test-dummy experiments conducted before Eustace’s flight revealed that a diver could enter a flat spin of 180 revolutions per minute.
“If you start spinning really fast, then it’s like if you were inside a blender,” Dr. Emmanuel Urquieta Ordonez, an assistant professor at Baylor University’s Department of Emergency Medicine and Center for Space Medicine in Houston, says. “The blood that normally needs to go to your brain to keep you awake and conscious will start going to your legs, and then you could technically pass out.” (Eustace used a drogue parachute to help stabilize his descent, but this method could become less reliable at higher altitudes.)
Maintaining pressure and temperature are the most important requirements of a suit like this, Urquieta Ordonez says. Above 62,000 feet, “either you need 100 percent oxygen, or you need to increase the pressure of the suit for the lungs to be able to move the oxygen into your veins,” he says. Above 60,000 to 62,000 feet, a demarcation known as the Armstrong limit, “any fluids—even saliva—will boil because there’s no atmospheric pressure to keep it in a liquid state,” he explains. The temperatures at these altitudes could be fatal, too.
The life-support systems within the suit—a clean supply of oxygen, a CO2 scrubber, water and cooling systems, for instance—would need to accommodate what could be an hours-long journey, depending on how high the diver jumps from. And there would likely need to be some sort of redundancy, meaning if one part of the life-support system failed, a backup would kick in.
The Risks of Reentry
Atmospheric reentry adds another layer of complexity. A space diver’s suit would need to withstand temperatures as high as 3,400 degrees Fahrenheit. Seedhouse says the options include either ablative materials, like those that burned off of the Apollo command module, or a tile system like the one used during the shuttle program. Altogether, Seedhouse estimates a suit replete with a propulsion system, a fully redundant life-support system, and heat shield could weigh as much as 500 pounds.
So, when will it be time to jump? The space tourism industry seems to be on the cusp of a major boom. Last year, SpaceX sent an all-private crew of astronauts to orbit and both Jeff Bezos’s Blue Origin and Richard Branson’s Virgin Galactic safely launched crews of private astronauts on suborbital flights. A slew of private space missions (orbital and suborbital) are planned for next year. Still, Seedhouse says it will be a while before even the ultra-wealthy can hurl themselves out of spacecraft and safely dive back to Earth.