STAR CITY, Russia (AP) -- The new crew to the international space station will conduct experiments to research new AIDS vaccines and plant growth, and work on new space vehicles that will help future missions to the moon and Mars, crew members said Thursday.

With nearly three weeks remaining before the launch of the Soyuz space craft, Russian cosmonaut Salizhan Sharipov and U.S. astronaut Leroy Chiao held their last news conference before their mission.

The Russian-built Soyuz craft is scheduled to blast off Oct. 11 from Russia's Baikonur cosmodrome in Kazakhstan. Sharipov and Chiao will replace Gennady Padalka and Mike Fincke, who are winding down a six-month mission on the orbiting station.

Cosmonaut Yuri Shargin also will travel into space, but is to return nine days later with Padalka and Fincke.

Russian space vehicles have provided the only link with the space station since the United States grounded the shuttle fleet after Columbia broke apart over Texas on Feb. 1, 2003, killing all seven astronauts on board.

"I think it is a service to the memory of the crew of the Columbia that we continue our work in space,'' Chiao told reporters at Russia's Star City, just outside Moscow. "I think exploration is something that is really innate to the human organism and something that kind of separates us from the other forms of life on earth.''

Sharipov said the pair will conduct at least two space walks - the first one scheduled for the end of the this year, when they will install antennas and cameras on the station's exterior.

In February, the pair is scheduled again to walk outside the station in preparation for the arrival of a European-built space cargo ship, the ATV Jules Verne, he said.

Chiao said the crew will also conduct medical experiments to help researchers find a vaccine for AIDS, and will begin tests on a new space vehicle that could be used in future missions.

"If we start sending vehicles to the moon and to Mars, we are no longer riding lower orbit wards where it is relatively close to home and you can just jump in a lifeboat and come home if something wrong happens,'' Chiao said.