NASA is looking into extending its space shuttles past their planned 2010 withdrawal from service, according to an e-mail made public over the weekend.

The move comes as the U.S. space agency faces a dilemma.

If it retires the shuttles as originally scheduled, it won't have an autonomous means to get astronauts or cargo to the International Space Station, or ISS, until at least 2014, when its next generation of spacecraft, the Orion, is slated to enter service.

NASA would have to rely on Russia allowing U.S. astronauts and payloads to piggyback on its launches, or — the current stopgap plan — it could buy Russian spacecraft and launch them itself.

The frost that has chilled U.S.-Russian relations during recent events in Georgia has made both of those alternatives unpalatable. So NASA is launching a study to determine how it might extend shuttle service.