Space station "railroad" problem solved

 作者:敖梁     |      日期:2019-03-05 10:08:01
By Will Knight NASA engineers have identified the technical glitch that upset the first test of the International Space Station’s mobile transporter. During Monday’s test, the unit’s software shut down all operations as the transporter attempted to lock into place at the first “work site”. The $190 million transporter travels along a set of rails attached to the ISS’s newly fitted S-Zero truss. The station’s robot arm Canadarm2 will eventually be attached to the transporter and moved to different work sites about the ISS. At these points the arm can be plugged into power and data points and used to carry out further construction work. Engineers believe that the locking procedure caused the transporter to rise slightly and disconnect from a sensor that is used to identify each work site along the rails. The transporter’s software consequently reasoned that the transporter was not in place and ordered the locking process to halt. Controllers overrode this software to successfully lock the transporter in place at the next work site along at 2340 GMT. “They ended up needing to do it manually rather than automatically,” a NASA spokeswoman told New Scientist. “There are finite changes due to micro gravity that do not occur on the ground.” The transporter will remain at this point until the next shuttle mission, which planned for autumn 2002. Being able to move the robot arm to different sites will allow further construction work to take place at the ISS. Eight more trusses are planned to complete a 109-metre frame at the outpost that will hold a 100-metre solar panel array. NASA’s first pair of spacewalking grandparents,