American astronauts cast votes in space

Two American astronauts currently in space already have voted and urged their Earth-bound compatriots to do the same in a message broadcast by NASA.

"Voting is the most important statement Americans can make. It's a cherished right," International Space Station Commander Edward Michael Fincke said in the pre-recorded spot.

"So this election day, take time to go to the polls and vote. If we can do it, so can you."

Fincke and ISS Flight Engineer and Science Officer Greg Chamitoff, orbiting the Earth at an altitude of some 354 kilometres, cast their votes by secure digital transmission on Monday, NASA officials said.

Mission Control at Johnson Space Center in Houston, Texas shipped digital ballots to the space voters, and local election officials sent passwords directly to them.

The ballots were returned, encrypted, via Mission Control.

Election officials worked closely with NASA to make sure Americans in space can vote, and vote confidentially.

"Nobody can get into the ballot," said Jennifer Ballard, election supervisor in Harris County, Texas. "You have to have the password to get into the ballot."

"We do a lot of things to try to support their stay on the space station, which can last six months or more," said Johnson Space Center spokeswoman Nicole Cloutier.

"We certainly don't want to deny them their privilege to vote in this election."

An American astronaut voted from space for the first time in 1997, from the Russian Space Station Mir, and since then a total of four Americans have voted in space.

A Texas law establishing special procedures for space voting was passed in 1997, NASA said.