A Soyuz spacecraft carrying three crew members is heading for the International Space Station after taking off from Russia's launch facility in Kazakhstan.
American astronaut Joseph Acaba and Russian cosmonauts Gennady Padalka and Sergei Revin were on board the Russian rocket, which blasted off around 11 p.m. ET Monday, or 9 a.m. Tuesday at Baikonur Cosmodrome in Kazakhstan.
A live video stream on NASA TV showed the preparations for the launch. Shortly after takeoff, the crew reported that everything was OK on board.
The trio will dock with the ISS early on Thursday for a four-month stay, joining three astronauts who have been on board since December.
The six will work together until July, when Oleg Kononenko of Turkmenistan, Don Pettit of the United States and Andre Kuipers of the Netherlands will head back to Earth. NASA, the Russian Federal Space Agency and the European Space Agency work together on the space station.
"Due to the facts that I will be launching on a Russian vehicle and the true international nature of the Space Station, my training has taken me to Russia, Canada, Japan and Germany," Acaba wrote on his blog.
On Friday, Acaba, Padalka and Revin completed their final inspection of the Soyuz vehicle, which was then rolled out to its launch pad on Sunday.
Soyuz rockets, which have been sending Russians into space since 1961, are now the only way crews reach the space station since the United States retired its space shuttle program in July.
The rockets have grown taller and have better electronics, but have basically remained the same over the decades, providing the highest number of launches of any spacecraft in the world.
On the station, the three crew members (part of the ISS's Expedition 31) worked on science experiments and cargo transfers as they awaited their new crewmates, NASA said.
Pettit conducted experiments about the effects of spaceflight on humans, the effectiveness of high-intensity exercise as a tool to guard against a loss of muscle mass and bone density in weightlessness, and how a variety of solid materials burn and extinguish in low gravity.
Meanwhile, Kuipers performed cargo operations and Kononenko performed routine maintenance on the life support systems.