Although the big satellites get most of the press, a lot of astronomy is done from balloons, huge mylar bubbles that can carry a gondola up to about 120,000 feet over the earth — more than 22 miles or 32 km. That’s high enough that much of the atmospheric contamination is gone, but a lot cheaper and easier to reach than orbit. I’ve been involved in the BOOMERaNG and MAXIMA balloon experiments, to measure the Cosmic Microwave Background, and currently with EBEX. Some experiments, BOOMERaNG among them, take advantage of the conditions at the South Pole and launches from Antarctica, using the “polar vortex” in the atmosphere to keep the balloon aloft for as much as a couple of weeks. (I should point out that for me, “involved with” means that I stay home where it’s warm and comfortable, but get to play with the data once my hardier colleagues return from the field.)
If you want to get a feel for ballooning, check out BLAST!, a film made of the campaign to fly the eponymous experiment (the acronym stands for Balloon-borne Large-Aperture Sub-millimeter Telescope), made by Paul Devlin, the film-maker brother of one the experiment’s Principal Investigator. It follows the team from their university labs to the Northern launch site in Scandanavia, and finally to Antarctica. I haven’t seen the whole thing yet, but I’m told it does a good job of giving the impression of the alternating excitement and boredom — and lofty goals — of these experiments.