(By Irene Klotz, Reuters) – A Russian Soyuz capsule carrying a NASA astronaut and two Russian cosmonauts arrived at the International Space Station on Friday, ending a nearly six-hour flight, a NASA TV broadcast showed.

U.S. astronaut Jeff Williams and cosmonauts Oleg Skripochka and Alexey Ovchinin blasted off from the Baikonur Cosmodrome in Kazakhstan at 5:26 p.m. EDT (2126 GMT) and reached the station at 11:09 p.m. EDT (0309 GMT).

They replace a crew that ended a nearly year-long flight earlier this month.

Williams, a grandfather and veteran of three previous spaceflights, noted that he has been in space with 45 different people over the years. He, Skripochka, who has flown once before, and Ovchinin, a rookie, will spend about six months living and working aboard the station, a $100 billion research laboratory that flies about 250 miles (400 km) above Earth.

The U.S. space agency and Russia have not yet assigned crews for additional year-long missions following the March 1 return of astronaut Scott Kelly and cosmonaut Mikhail Kornienko from a 340-day spaceflight.

Williams, 58, who will be serving aboard the station for a third time, is expected to return to Earth with a career total of 534 days in space. This would surpass the current U.S. record, which is Kelly’s cumulative 520 days.

The Soyuz TMA-20M spacecraft carrying the crew of Jeff Williams of the U.S., Alexey Ovchinin and Oleg Skripochka of Russia blasts off to the International Space Station (ISS) from the launchpad at the Baikonur cosmodrome, Kazakhstan, March 19, 2016. REUTERS/Shamil Zhumatov

Above: The Soyuz TMA-20M spacecraft carrying the crew of Jeff Williams of the U.S., Alexey Ovchinin and Oleg Skripochka of Russia blasts off to the International Space Station (ISS) from the launchpad at the Baikonur cosmodrome, Kazakhstan, March 19, 2016. REUTERS/Shamil Zhumatov

The world record belongs to Russian cosmonaut Gennady Padalka, who returned from his fifth flight last September and has spent a total of 879 days in space.

“I feel very ready to be going back to the space station,” Williams said in an NASA interview before the launch.

Scientists are interested in seeing how the human body fares during longer stays in space as the United States and other countries are planning for multi-year missions to Mars.

In addition to more exposure to radiation, astronauts experience bone and muscle loss and changes in their cardiovascular, immune and other systems.

Williams, Skripochka and Ovchinin join a three-man crew already aboard the station. The crew has been preparing for the arrival of an Orbital ATK cargo ship, which is scheduled to blast off from Florida on Tuesday.

(Reporting by Irene Klotz; Editing by Tom Brown and Tom Hogue)