A Russian spacecraft carrying two crew and billionaire space tourist Charles Simonyi has docked with the International Space Station (ISS).
Simonyi flew with two professional cosmonauts
The three men transferred to the ISS after a two-day flight from Earth.
Mr Simonyi, 58, paid $25m (£12.7m) for the trip. He is the fifth space tourist and will spend 10 days aboard the ISS.
The Hungarian-born US software engineer is the 450th person to enter orbit and, by his own admission, "the first nerd in space".
The Soyuz craft docked at 1910 GMT, the Russian space centre said.
Among the cargo is a gourmet meal of roast quail marinated in wine and duck breast, selected by American lifestyle guru Martha Stewart, a friend of Mr Simonyi.
It is to be consumed on Thursday, when Russia marks Cosmonauts Day.
Speaking to Mr Simonyi over the communications system at mission control, Ms Stewart told him: "You are now truly out of this world."
Mr Simonyi is due to return to Earth on 20 April, along with Russian Mikhail Tyurin and US astronaut Miguel Lopez-Alegria who have been on the ISS since September.
Another US astronaut, Sunita Williams, will remain on board with incoming cosmonauts Fyodor Yurchikhin and Oleg Kotov of Russia.
Mr Simonyi is to carry out a series of experiments including measuring the amount of radiation he is exposed to while on board the ISS.
The aim is to help to generate an accurate map of the station's radiation environment.
Mr Simonyi began training for the flight six months ago at the Yuri Gagarin Cosmonaut Training Centre in Star City, Russia; and at the Baikonur Cosmodrome in Kazakhstan.
He underwent a gruelling physical programme, including strict medical tests, to prepare him for the ride to escape the Earth's atmosphere and his time onboard the ISS.
The 58-year-old was born in Hungary but now lives in the US, where he amassed a fortune through his work on computer software, including helping to develop Microsoft Word and Microsoft Excel.
His trip was arranged by US-based Space Adventures.
The firm has previously sent four private explorers to space:
- American Dennis Tito in 2001
- South African Mark Shuttleworth in 2002
- American Greg Olsen in 2005
- Iranian-born US businesswoman Anousheh Ansari in September 2006.