The National Science Foundation (NSF) and the National Aeronautics and Space Administration (NASA) said today they had set a new record in the almost 20-year history of scientific ballooning in Antarctica, by launching and operating three long-duration sub-orbital flights simultaneously within a single southern-hemisphere summer.
Scientists use data collected from such high-altitude balloons to study ultra-high-energy cosmic rays, search for anti-matter and look at other environmental or astrophysical experiments.
The NSF supports long-duration balloon flights in Antarctica to conduct astrophysical experiments. Circling the continent on unique stratospheric winds at altitudes of roughly 23 miles for periods of up to 31 days, experiments operate in an area that is almost free of atmospheric interference. For some experiments, this provides scientists with conditions equivalent to flight aboard a satellite or the space shuttle, at much lower cost.
The key payloads this winter were: The University of Maryland's Cosmic Ray Energetics And Mass (CREAM) payload which was launched on Dec. 19; the Balloon-borne Experiment with a Superconducting Spectrometer (BESS-Polar) payload from NASA's Goddard Space Flight Center and Japan's High Energy Accelerator Research Organization (KEK), launched on Dec. 22; and Louisiana State University's Advanced Thin Ionization Calorimeter (ATIC) was launched on Dec. 26. Each of these large-aperture instruments is similar in size to an observatory class satellite.
The Antarctic is unique in that the atmosphere lets the balloons make long-duration flights that easily circle the continent. First, a nearly circular pattern of gentle east-to-west winds establishes itself in the Antarctic stratosphere lasting for a few weeks. The circulation is generated by a long-lived high-pressure area caused by the constant solar heating of the stratosphere. This allows the launching and recovery of a balloon from roughly the same geographic location and permits a flight path that is almost entirely over land, according to the NSF. Constant daylight in Antarctica means no day-to-night temperature fluctuations on the balloon, which helps the balloon stay at a nearly constant altitude for a longer time, researchers said.
Second, because the sun never sets during the austral summer, the balloon is illuminated continuously, both directly and by reflection from the underlying clouds or snow. As a result, the balloon maintains a constant temperature and is able to maintain a stable altitude. In other areas of the world, the daily heating and cooling cycles change the volume of gas in the balloon, causing it to rise and fall and expend ballast, severely limiting flight times, according to the NSF.
As an international zone under the Antarctic Treaty, balloons can be launched, flown and recovered anywhere on the continent without diplomatic complications experienced in other areas of the globe, the NSF said.
The milestone is significant, as it occurs during the height of the International Polar Year (IPY), a coordinated scientific campaign that is utilizing scientists from more than 60 nations. NSF is the lead federal agency for IPY, which began in March 2007 and will continue until 2009 to allow for two full years of observations and field work in parts of the world that are generally uninhabitable for as long as six months each year, researchers said.