The ups and downs of space
- October 5, 2012 1:55 PM |
- By Quirks
By Bob McDonald, Quirks & Quarks
Next week, if all goes well, two events, traveling in opposite directions, will take place in space - both of them private enterprises. Space-X will launch its Dragon capsule up to the International Space Station, and Austrian daredevil Felix Baumgartner will skydive from the edge of space.
The Space-X launch will be the first of 12 launches, under contract by NASA, to service the International Space Station. Hopefully, it will be a routine event, even though the company has done this just once before. But that first test flight last May was so successful that NASA has approved a full service mission on only the second flight, something NASA itself has never done. The capsule will bring up supplies and experiments for the astronauts already in orbit.
NASA is anxious for private space flight to get off the ground because the only way to reach the space station (whether for supplies or astronauts) since the space shuttles have been retired is on Russian Soyuz capsules - something the Americans find embarrassing. Facing more budget cuts, NASA is hoping that the private sector will keep Americans flying on American rockets from American soil.
The other event, a downward trip by Felix Baumgartner, is an attempt to break several world skydiving records. He will be carried to an altitude of 36.5 km (120,000 feet) above Roswell, N.M., by a helium balloon, in what looks a lot like the Dragon space capsule. At that altitude, he will see the blackness of space and the curve of the Earth below. Wearing a pressurized space suit, he will step out into what is essentially a void. The atmosphere at that altitude is only 0.5 per cent of what it is on the ground. The air is so thin he will not hear the sound of wind rushing by his helmet when he first leaps out.
But within the first 30 seconds of his dive, things will get very noisy. Without much air resistance to get in the way, his body will accelerate very quickly, due to gravity. If he exceeds 1,225 km/hr, he will become the first human to break the sound barrier without a vehicle. At that point, he will be buffeted by a shock wave that will form first around his helmet, and then work its way along his body, down towards his feet. His specially designed suit will have to protect him from the pressure and heat generated by the wave, which will radiate out sideways as a flat circular disc, with Felix punching a hole through the centre. That will be the most dangerous part of the dive.
From that point on, Felix will feel an upward pressure on his chest (if he's facing the right way) as he runs into denser air below that will slow him down to the speed of a regular skydiver.
Felix says his dive is more than a stunt - it is a test of technology that could be used as emergency equipment for pilots, astronauts and space tourists. However, unless those people are flying in balloons, this technology will not be of much use.
First of all, few aircraft can reach those altitudes, and when something does go wrong, pilots, who already wear pressure suits, tend to stay with their aircraft as long as possible to try to save it before bailing out.
Astronauts who step out of an orbiting spacecraft cannot freefall back to Earth, because they are traveling at more than 28,000 km/hr. Hit the air at that speed and you will burn up, which is why returning spacecraft have to be protected by heat shields. Felix will be jumping from an almost stationary platform, straight down, and while supersonic is fast, an orbiting spacecraft is moving 25 times faster.
Space tourists, such as those paying for flights on Virgin Galactic, will essentially go straight up and down from space like a baseball thrown into the air, and only get a few minutes of weightlessness at the top of the arc. That is not enough time to get into a bulky pressure suit and bail out if something goes wrong. The tourist rockets are designed so people can float around inside the cabin, unencumbered, and enjoy the view - not be strapped into a bulky space suit the whole time.
So, while the skydive from the edge of space may not have many practical applications, it is an astounding feat for a human. And these two events - a privately funded skydive from space and a commercial delivery to space - are a demonstration of both the indomitable spirit that has driven humans to go where no one has gone before, and once we do, our ability to find ways of making money doing it.
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