Balloon-Borne Experiments
Why Use Balloons Instead of Satellites?
Balloons are much less expensive than satellites. The least expensive satellites cost over $120 million for the equipment and launch whereas, balloon flights cost only a fraction of that while still collecting good data.
When Was the First Balloon Borne Experiment?
In 1912, Austrian physicist Victor Hess along two assistants manned a balloon at 16000 ft, discovering that ionizing radiation levels increased with altitude and thus mostly did not originate from the earth itself. Hess won a Nobel Prize in 1936 for his discovery of cosmic rays.Antarctic cosmic-ray balloon flights began in 1947, when Martin Pomerantz send the first unmanned balloon to 127,000 ft. The United States opened its first Antarctic naval base in McMurdo in 1956, but did not begin launching multi-day balloon experiments until 1988.
For more information about McMurdo balloon launches, visit http://stratocat.com.ar/bases/41e.htm.
When Do the Balloons Launch?
The December 10 - January 10 launch window for McMurdo Station in Antarctica is determined by the seasonal polar wind circulation pattern necessary to maintain the balloon trajectories over the continent. The payloads can then hopefully be recovered and used for subsequent flights.
Why Antarctica?
Antarctic balloon flights can last much longer than flights in other places because of the polar vortex and because there is very little atmospheric or temperature change. Constant daylight in Antarctica means no day-to-night temperature fluctuations on the balloon, which helps it stay at a nearly constant altitude during the flight.
Unique atmospheric circulation over Antarctica during its summer months allows scientists to launch balloons from a site near McMurdo Station, the Foundation's logistics hub in Antarctica, and recover them from nearly the same spot weeks later. During that time, each balloon circles the continent one to three times. Scientists from the United States, Japan, South Korea, France and other countries are using the balloons to investigate the nature of ultra-high-energy cosmic rays and to search for antimatter.
The information from this answer came from this NASA news article.