NASA -- In June 1999, astronauts on the space shuttle deployed an 87-lb beach-ball sized satellite designed to study the effect of solar activity on Earth's atmosphere. The satellite, named STARSHINE, is a hollow aluminum sphere covered with 1 inch-square mirrors. Observers have been tracking the ball for over 9 months by means of reflected sunlight. STARSHINE was often visible to the naked eye in the evening sky from distances greater than1000 miles.

Usually space scientists like their satellites to stay in orbit as long as possible, but STARSHINE will accomplish its goals in a different way -- by falling back to Earth.

STARSHINE is falling slowly in altitude with each orbit as it encounters the fringe of the Earth's atmosphere. Eventually, the atmospheric drag will become too much and STARSHINE will reenter the atmosphere, burning up like a slow bright meteor or fireball. Best estimates from the STARSHINE orbit decay site currently place reentry on February 18 at about 07:07 UT, with an uncertainty of plus or minus 14 hours.

Around the time of solar maximum, which is expected to begin in mid-2000, the extra ultraviolet and X-radiation created by magnetic fields around sunspots causes the Earth's atmosphere to heat up and expand. Radiation from solar flares also ionizes the upper atmosphere, which leads to more expansion. A satellite's orbit around the Earth can be disturbed by the enhanced drag from the swollen atmosphere. That's the idea behind STARSHINE. By watching how the diminutive satellite's orbit decays, scientists can deduce the extent and density structure of the upper atmosphere as we approach the peak of the sunspot cycle.

Mitch Battros
Producer - Earth Changes TV
http://www.earthchangesTV.com