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Into Thin Air


Early in 2005, champion skydiver Cheryl Stearns will make the highest free-fall jump in history from the edge of space. The StratoQuest mission's aim is to test new equipment that may enable astronauts to bail out of a stricken shuttle. It is badly needed research, as the Columbia disaster has shown. Stearns tells Barry E. DiGregorio how it all started with a dream.

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Describe what will happen during the jump.

The balloon ascent will take about 2 1/2 hours to reach 130,000 feet under ideal conditions. The ride down from the stratosphere will take about 10 1/2 minutes - 5 1/2 minutes for the free fall and another 5 minutes after my parachute opens. If I bail out at 130,000 feet and nothing goes wrong, I will reach Mach 1 in 47 seconds. Once I hit an altitude of 100,000 feet the atmosphere will thicken, and atmospheric friction will start slowing me down.

My maximum free-fall speed will be around 1150 kilometres per hour, though because of the thinness of the atmosphere it will feel like only 4 kilometres per hour. The speed I reach will depend on my body position on the way down. If I go into a head-down dive I could go much faster, and I may reach a speed of Mach 1.3. I don't know whether I will create a sonic boom. At 130,000 feet it will be about 0 °C . Above 70,000 feet you are into the ozone layer and the air is relatively warm. But between 30,000 and 70,000 feet it will be colder - around -35 to -70 °C.

I will open the parachute at 7000 feet so that by the time I reach 5000 feet I will be under a full canopy - you need 2000 feet of leeway for this parachute to fully deploy. By this stage I will have slowed to a speed of around 240 kilometres per hour due to friction.

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Posts: 13123 | Registered: Feb 2002  |  IP: Logged | 

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There is something really, really cool about a human creating a sonic boom.

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Posts: 11895 | Registered: Apr 2002  |  IP: Logged |