The Walker Expedition was sent in the 42nd century to bring back the power source that kept the planet Krop Tor in a stable orbit around the Black hole K37 Gem 5.
Only Captain Zachary Cross Flane, Ida Scott and Danny Bartock returned alive after the drilling awoke The Beast. Captain Walker had been killed soon after the Base was built,
Krop Tor
Mr. Jefferson died while trying to stop the Ood in the ventilation shafts, Scooti Manista was killed by Toby Zed while he was under the influence of The Beast and Toby was killed by Rose Tyler who blew him into space due to his possession. The rest of the crew members were killed by the Ood. The Ood themselves died when the planet collapsed into the black hole. (DW: The Impossible Planet / The Satan Pit)
The Walker Expedition had some affiliation with the Torchwood Archives. Expedition leader Zachary Cross Flane (who replaced Captain Walker, who presumably also knew) knowingly worked for them. Other crew members may not have done.
Known Crewmembers:
Captain: Walker
Acting Captain: Zachary Cross Flane
Science Officer: Ida Scott
Ethics Commitee: Danny Bartock
Archeoligist: Toby Zed
Security Chief: John Jefferson
Trainee Maintence Officer: Scooti Manista