“Preliminary investigation shows that two of Link’s three reaction wheels currently are not operable, and there is some loss of functionality in its cold gas thruster system,” NASA said. Reaction wheels work by discharging momentum to control the pointing, or attitude, of a spacecraft in orbit. The electric thrusters are one of the most critical elements of the rescue mission. They are used for orbit raising to allow Link to rendezvous with the Swift satellite some 200 miles above Earth. Katalyst is now calling upon the electric thrusters to stabilize the Link spacecraft’s attitude, something they were not intended to do.