NanoSail-D2, a replacement satellite for Nanosail-D which was lost during a rocket failure, was a small satellite built by NASA's Marshall Space Flight Center in Huntsville, Alabama and NASA Ames Research Center in Mountain View, California. Launched on November 20 last year, NanoSail-D2 was tasked with studying the effects of the upper atmosphere on a deorbiting satellite with a "large low mass surface area sail." NASA said.
NanoSail-D2 eventually deployed a solar sail, and it was the first satellite to use a solar sail in low-Earth orbit. For more than 240 days, NanoSail-D2 orbited the Earth with an orbital decay that would eventually send it plummeting through the atmosphere.
The rate at which the satellite's orbit decayed was dependent on a number of factors including the solar activity, atmospheric density at the present altitude of the satellite, and the angle of the sail to the orbit's path. While NASA says that it's still evaluating data, Dean Alhorn, principal investigator for NanoSail-D at Marshall Space Flight Center, says that solar flares during the deorbit increased the drag and brought the nanosatellite down more quickly - most solar sails tend to utilise solar energy to fight drag and move the craft into a higher orbit.
Now that the mission is complete, researchers can use what they learned to help predict deorbital patterns, and maybe even help create a controlled deorbit utilising a solar sail that would allow a satellite to completely burn up in the atmosphere, preventing any dangers associated with a dead satellite hitting the Earth.