The New York Times provided live updates about the launch.

When Scott J. Kelly goes up to the International Space Station — he and two Russian astronauts are scheduled to launch on Friday — he will not come back down again for a year.

That year is to be the longest space mission a NASA astronaut has ever undertaken. This trip — Mr. Kelly’s fourth to space — will also push him to the top in cumulative time in space among NASA’s astronauts. When he lands in March 2016, he will have spent more than 500 days of his life floating in orbit, including a 159-day trip to the space station that ended in 2011.

With his trip this time twice as long, “my expectation is that it’ll be more challenging and, as a result, more rewarding,” Mr. Kelly, 51, said in a recent interview.

Like all travelers to the space station since the retirement of NASA’s space shuttles in 2011, Mr. Kelly and the two Russians, Mikhail Kornienko and Gennady Padalka, will be launching on a Russian Soyuz rocket from the Baikonur Cosmodrome in Kazakhstan. Liftoff is scheduled for 3:42 p.m. Friday Eastern time, which is 1:42 a.m. Saturday in Baikonur. The Soyuz capsule will dock at the space station about six hours later.