MARCH 2007 IN
RICK ASTER’S WORLD

Space Jumping

Could a person jump off a platform in space and land on the ground?

In a recent dream, I was attending a festival. As part of the event, two men identified as “space jumpers” jumped from a platform in outer space and in less than two hours landed, with much fanfare, on a field on the festival grounds.

After the landing, people went out to the field to talk to the space jumpers as they disconnected from their gear, which included sky boards, wings, and ordinary parachutes. I had never heard of such a thing and was quite impressed.

It was all a dream, but could something like that really be possible?

Space Diving

As I found out, people are already working on this, and the parts that would seem to be the most difficult have already been sorted out and demonstrated. Canadian Arrow is a company developing technology for recreational space flight. It takes one minute on a rocket to propel their capsule into the thermosphere, from which it descends on parachutes. In 2004, the company demonstrated the launch, descent, and recovery of its capsule over Lake Ontario.

People looking for a bigger thrill than that could someday go space diving. They would exit the capsule after it goes into free fall in order to return to the surface on individual parachute systems. The company shows individual re-entry system designs from the Gemini space program.

A similar system was actually tested in 1960 when a U.S. Air Force officer sky-dived from a height of 31.3 kilometers. From that height, it took 13 minutes to reach the ground. For the past five years, space diving enthusiasts have been attempting to duplicate this feat, with some success. The main limiting factor is the difficulty in getting balloons to go so high up.

An altitude of 30 kilometers is significant because, when you are talking about flying, this is around the upper limit of the atmosphere. The altitude record for a person in a balloon is 34.6 kilometers; in an airplane, 25.9. The air is not thick enough to go much higher. At 30 kilometers, the atmospheric density is 1/100 of the surface air pressure we are used to. If you were descending from space, you would want to slow down from the high speeds of outer space to a speed similar to land speeds before you hit this lower, thicker part of the atmosphere.

Speed

Speed, it turns out, is the crux of the problem in space jumping. A “stationary platform” in space near Earth would actually be circling the planet at a speed of at least 7,000 meters per second. That kind of speed is nothing compared to the speeds of objects in space, but it is too fast to be going when you hit the atmosphere. The air would slow you down, but the friction could generate a dangerous amount of heat.

Of course, there are ways to get around this. In my dream, the space jumpers generated air braking in the upper levels of the atmosphere with large inflated wings, somewhat similar to paraglider equipment, that deflated when they got into thicker air near the clouds. In reality, aerospace engineers have been studying shuttlecock designs for this purpose. These designs have large air braking mechanisms, called feathers, behind a re-entry vehicle. This provides a large area for air braking and keeps the heat away from the vehicle. At the same time, it keeps the vehicle pointed in the right direction, preventing it from going into a spin. A blunt cone shape at the front diverts most of the heat away, so that it does not accumulate in the descending spacecraft. Engineers think such a system could work for a heavy spacecraft; a much smaller version of the design might work for an individual.

The designs actually in use in space flight are based on wings and parachutes, and there is every reason to think that elements of these designs could work on an individual scale.

One way or another, you have to slow down from the 7,000 meters per second of orbital speed to something like 1,000 meters per second in the upper atmosphere, and you have little time to spare to accomplish this. It is not so far from outer space to the ground. There is no borderline between the atmosphere and outer space, but most people agree that 100 kilometers above ground counts as outer space. If you think of traveling 100 kilometers by highway or railroad, it is a distance you can cover in an hour or less. It is hard to imagine that you could slow yourself down enough to cover this vertical distance in a controlled descent lasting much more than an hour. The key, though, is to get to the atmosphere with little enough velocity that the air can slow you down.

Once you arrive in the lower atmosphere, the air slows you down to 54 meters per second even without any equipment, and with a parachute, you can make a relatively soft landing with a measure of control over where you land. This is actually the difficult part of space jumping, yet the techniques of parachuting were sorted out almost a century ago, and there is nothing in parachute equipment that would not be able to survive a short trip through outer space. Sky-divers routinely jump through 40 percent of the atmosphere. The idea of space jumping extends the jump through the other 60 percent of the atmosphere.

Every day space rocks fall to the ground and land intact. It is not that hard to imagine that a person with the right equipment could do so too.

Creature comforts

If you could work out how to aim it, a small cargo package could manage the kind of jump I described with little difficulty. But people are not cargo, and we would need some protection from the elements to make the jump.

A person in a low-pressure situation needs pressure to hold the body together. The human body is adapted to atmospheric pressure, but you could use the pressure of stretch fibers, essentially bodywear, in its place. On your face, you will need at least some kind of special pressurized mask.

The mask would also deliver air to breathe. You would need thermal insulation against both the cold of the middle atmosphere and the heat of air braking. Canadian Arrow believes this can all be integrated into a single space-diving suit that could be no more complicated than scuba gear.

I admit there are a lot of details to be worked out, but when you take a close look at it, space jumping is not as far-fetched as it seems at first glance. When you look at how little equipment and energy it seems to require compared to landing a space vehicle on the ground, space jumping might eventually become a regular part of space travel.


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