NASA’s prototype solar sail spacecraft will continue to orbit Earth for a few more months, the U.S. space agency said April 26.

NASA’s NanoSail-D satellite was originally expected to burn up in Earth’s atmosphere 70 to 120 days after unfurling its 100-square-foot solar sail, which happened Jan. 20. But the satellite is descending more slowly than anticipated, meaning it should stay aloft at least until July, NASA officials said.

“NanoSail-D has lowered its altitude above the Earth by approximately 28 miles (45 kilometers) from its original altitude of 400 miles (640 kilometers), and continues to descend,” said Dean Alhorn, NanoSail-D principal investigator at NASA’s Marshall Space Flight Center in Huntsville, Ala. The mission team, Alhorn added, now “predicts NanoSail-D will continue to descend and eventually re-enter Earth’s atmosphere and disintegrate six months to one year from sail deployment.”

NASA and the skywatching website are holding a NanoSail-D space photography contest for the best photos of the solar sail. First prize is $500.

In North America, a good viewing window opened April 27 and should continue for 10 to 14 days. For the best look, skywatchers should seek out NanoSail-D passes to the west of the viewing location, officials said.

The change in NanoSail-D’s deorbiting plans is in keeping with the little satellite’s mission, which has been full of surprises so far.

NASA launched the NanoSail-D solar sail — the core of which is about the size of a loaf of bread — Nov. 19 from the Alaska Aerospace Corp.’s Kodiak Launch Complex aboard a Minotaur 4 rocket. The satellite’s primary mission was to demonstrate a compact solar sail system. The technology could lead to further development of solar sails for future missions, and could help satellites deorbit cheaply and efficiently, mission managers have said.

At launch, NanoSail-D was one of six scientific payloads aboard a larger satellite called FASTSat, which stands for Fast, Affordable Science and Technology Satellite.

On Dec. 6, NASA engineers triggered the ejection of NanoSail-D from FASTSat, but it apparently did not work. Then, on Jan. 19, officials announced that the little satellite had spontaneously popped out of its mothership.

Two days later came more good news: NanoSail-D had successfully deployed its solar sail.

“The NanoSail-D mission is NASA’s first compact structure to deploy in low Earth orbit and will be the first solar sail to deorbit,” said Joe Casas, FASTSat project scientist at Marshall. “The NanoSail-D mission continues to provide a wealth of data that will be useful in understanding how these type of deorbit devices react to the upper atmosphere.”

The NanoSail-D team has been monitoring the craft’s orbital characteristics since sail deployment. They have found that the satellite is orbiting Earth in a flat spin rather than the expected random tumble.

The flat spin attitude causes NanoSail-D to encounter less atmospheric drag, keeping it aloft longer than anticipated, researchers said.