Scientific balloon, 1 January 2002.
© National Aeronautics & Space Administration / Science & Society
'When scientists need longer exposure times in high altitudes, they use scientific balloons like the one pictured here. Made of a super-thin polyethylene, the balloons are filled with inert helium and can be launched from almost anywhere, staying aloft for as long as 24 hours, 26 miles above the surface. Goddard Space Flight Center assumed the management of these research tools from the National Science Foundation in 1982 and now launches about 35 balloons a year.'