How high is space, how far can you fall with a parachute, where is the Project Calliope satellite going to be, and where does the hard radiation from the sun get nasty? Gathered for the first time in one place is our High Altitude Explorer's Guide.
A typical airplane cruises at 9km (6 miles) up, around 30,000 feet. Military jets (from the SR-71 onward to modern planes) can hit over 30km (19 miles) up, over 100,000 feet.
Can you parachute from that height? Yes, in 1960 Joseph Kittinger set the record at 31.3km (19.5 miles), or 102,800 feet. Felix Baumgartner is trying this year, 2010, to freefall from 36km (over 22 miles), an 118,000 feet fall.