Two U.S. astronauts aboard the International Space Station have voted in a presidential election that is out of this world.

NASA astronauts Edward Michael Fincke and Greg Chamitoff used a secured digital transmission to cast their ballots for Tuesday's U.S. election.

The astronauts received their electronic ballots from NASA's Mission Control in the southern state of Texas. Local election officials separately sent them passwords via e-mail.

John McCain and Barack Obama

The votes will be counted by officials in the Texas counties where the astronauts live.

Fincke and Chamitoff did not reveal whether they voted for Democratic Senator Barack Obama or Republican Senator John McCain.

But in a televised message, they urged voters to get to the polls and fulfill their civic duty, saying, "If we can do it, so can you."

Texas passed a law in 1997, allowing NASA's Houston-based astronaut corps to join the democratic process while in space.

Since then, four Americans have voted while in orbit. The first astronaut to vote in a presidential election cast his ballot in the 2004 race.

Some information for this report was provided by AFP.