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Huge Balloon Lofts New Telescope
Science Daily is reporting that a new solar telescope has been launched via an enormous balloon filled with helium. Dubbed project "Sunrise" the National Center for Atmospheric Research (NCAR), NASA, Germany's Max Planck Institute for Solar Physics, Spain's Astrophysics Institute of the Canary Islands, and the Swedish Space Corporation all partnered to launch the balloon in order to view never before see features of the Sun. "The project may usher in a new generation of balloon-borne scientific missions that cost less than sending instruments into space. Scientists also can test an instrument on a balloon before making a commitment to launch it on a rocket. The balloon, with its gondola of scientific instruments, was launched successfully on the morning of October 3 from the Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. It flew for about 10 hours, capturing stable images of the solar surface and additional data from the various instruments of the sophisticated payload. The gondola then separated from the balloon and descended with a parachute, landing safely in a field outside Dalhart, Texas."
The payload (SUNRISE) is designed to carry a 1-meter telescope with a full complement of scientific instruments. This flight had a small (30 cm) stand-in telescope, to test the active pointing system, and a camera with a small array of narrowband filters, to see what wavelengths are visible from the flight altitude.
Strangely enough, some the components of sunlight at 120,000 feet altitude are not well known. Some interesting ultraviolet lines (the "h" and "k" lines from Magnesium) are thought to be visible there, that are not visible on the ground -- but nobody has yet characterized the ultraviolet absorption spectrum from the very upper layers of the stratosphere and from the mesosphere. Most telescopes that have flown so high were rocketing through on their way to space, rather than floating under a balloon. So this first flight was both to test the pointing (and other flight control) systems, and to double check that some desired wavelengths are present and usable at the target altitude.
Even the test flight of SUNRISE was a real accomplishment: it is far from the ideal of small, cheap, lightweight, quick-and-dirty payloads under scientific balloons, and is run more like a space mission both in terms of payload complexity and in terms of team management. The team is multinational and the payload is subject to rigorous engineering and testing.
The balloon flight environment is in some ways more harsh than the vacuum of space: payloads are subjected to wild temperature swings on climbout, and the thermal environment is not nearly as controllable as it is in empty space. On the other hand, launch and flight are very gentle compared to unmanned space shots.