This article was updated at 6:25 p.m. ET.
A Russian Soyuz spacecraft arrived at the International Space Station today (Dec. 17), carrying the three newest members of the orbiting laboratory's crew.
The Soyuz TMA-20 with NASA astronaut Catherine Coleman, Russian cosmonaut Dmitry Kondratyev and European astronaut Paolo Nespoli docked at the space station at 3:12 p.m. EST (2012 GMT) after a two-day orbital journey. The trio launched from the Baikonur Cosmodrome on the frigid steppes of Kazakhstan in Central Asia on Dec. 15.
Coleman, Kondratyev and Nespoli docked to the station's newest port ? the Earth-facing Rassvet berth ("Rassvet" is Russian for "Dawn"). After a series of tests to check the seals between the Soyuz and the space station, the spaceflyers opened the hatches between the spacecraft at 6:05 p.m. EST (2306 GMT).
Shortly after floating through and entering their new home-away-from-home, Coleman, Kondratyev and Nespoli called down to Earth, where their families were gathered at Russian Mission Control.
"Hi Mom, it's Jamie," one of Coleman's sons radioed up. "I miss you a lot and I'll take care of Dad."
"I know you will. I miss you too," she replied.
The arrival of the three crewmembers rounds out the station's existing Expedition 26 crew, made up of station commander Scott Kelly of NASA and flight engineers Alexander Kaleri and Oleg Skripochka of Russia, who launched to the station on Oct. 7. [Graphic: Inside and Out: The International Space Station]
Life on the space station
Coleman, Kondratyev and Nespoli are beginning a five-month stay in space, and as members of Expedition 26, they will participate in a wide array of research experiments and educational outreach.
"Now that we have a six-person crew, we're going to try to average 30 hours a week on various types of science," station commander Scott Kelly said in an interview conducted before the Soyuz launch. "Hopefully we'll have great results from the scientific experiments that we're able to do onboard."
The experiments are primarily geared toward understanding how the alien environment of space affects people, particularly over the long term. In a preflight interview, European Space Agency astronaut Paolo Nespoli said he will be involved in over 60 experiments in various disciplines.
The crewmembers will also be required to conduct maintenance activities and general station upkeep.
Russian cosmonauts Skripochka and Kondratyev also plan to carry out two spacewalks to install an antenna to complete an information transfer system that sends large computer files to and from the space station. The spacewalks are currently scheduled for Jan. 21, 2011 and late February.
Monitoring space traffic
The station crew will also be kept busy with the arrival of several different vehicles to the station. Three unmanned cargo supply vessels are set to dock at the station in the new year.
A Japanese H-II Transfer Vehicle (HTV) is scheduled to launch Jan. 20 from the Tanegashima Space Center in Japan, and will dock to the Earth-facing port on the station's Harmony module on Jan. 27.
The European Automated Transfer Vehicle (ATV), named after famed mathematician and astronomer Johannes Kepler, is set to launch from Kourou, French Guiana on Feb. 15. It will then dock to the aft port of the Russian Zvezda service module on Feb. 26.
The Russian Progress 41 resupply vehicle is scheduled to launch from Baikonur in Kazakhstan on Jan. 28 and will dock to the Pirs docking compartment on Jan. 31.
In addition to the various cargo ships, the space station will also host two visiting space shuttle missions early next year. Discovery's final mission (STS-133) is currently planned for early February, and will deliver the last pressurized U.S. segment to the station ? a space closet that will be attached to the nadir side of the station's Unity node.
In April, the space shuttle Endeavour is also set to make its final flight to the space station. In addition to carrying supplies, Endeavour will ferry an ambitious experiment, called the Alpha Magnetic Spectrometer, to the station. The 15,000-pound (6,800-kg) cosmic-ray detector will be installed on the top side of the station's truss, and will be used to search for antimatter galaxies and elusive dark matter.
During their five-month stay onboard the station, Coleman, Kondratyev and Nespoli will also take part in marking several significant milestones and anniversaries in spaceflight history, NASA officials said. These include the 50th anniversary of the first human spaceflight by Russian cosmonaut Yuri Gagarin on April 12, the 30th anniversary of the first space shuttle flight, also on April 12, and the 50th anniversary of the first American human spaceflight (May 5).
The six-person Expedition 26 crew will spend about three months together before Kelly hands over command of the station to Kondratyev, who will lead Expedition 27. Kelly, Kaleri and Skripochka are set to return to Earth in mid-March, while Coleman, Kondratyev and Nespoli will live on the station until May.
- Graphic: Inside and Out: The International Space Station
- Gallery: Space Windows on the World
- Is the International Space Station Worth $100 Billion?
You can follow SPACE.com Staff Writer Denise Chow on Twitter @denisechow.