Discovery To Dock With Space Station
By Frank Morring, Jr. 
JOHNSON SPACE CENTER, Houston - Astronauts on the space shuttle Discovery are preparing to dock with the International Space Station on March 17, after wrapping up their inspection of the orbiter's fragile thermal protection system March 16 and finding no obvious damage.
Docking will come at 5:13 p.m. EDT, after the now-routine rendezvous pitch maneuver to give the station crew a chance to use telephoto lenses to check Discovery's belly for damage as it flies a back flip while approaching from below at a range of 600 feet. After that, Mission Commander Lee Archambault and Pilot Tony Antonelli will maneuver Discovery to the front of the station's Harmony node, where it will dock with the pressurized mating adaptor with its tail pointing to the Earth.
That task will be a little simpler than might have been the case had space station managers decided to maneuver the orbiting laboratory out of the path of a troublesome piece of space debris tracked earlier in the week. Paul Dye, lead shuttle flight director of the STS-119 mission, said late March 16 that the debris moved into the "green" category as ground tracking station got a better fix on its orbit over time.
That means the suspect object was considered such a low-risk threat - less than one chance in 100,000 of a hit on the station - that the avoidance maneuver wasn't needed. As a result, the station will be right where the shuttle crew originally expected it to be, and the shuttle won't have to change its rendezvous trajectory to accommodate a new station orbit.
Last week, station astronauts had to take temporary refuge in the station's Soyuz lifeboat while another piece of debris from a spent rocket stage passed nearby (Aerospace DAILY, March 13).
Dye said that so far the mission has been "really clean," with a jammed ergometer for crew exercise the only anomaly that hasn't been solved yet. Even if the microgravity exercise bike can't be fixed, the crew can maintain muscle tone with bungee-based exercises or perhaps use the gear on the space station.
No obvious problems were spotted during inspections of the orbiter, although Dye stressed that the real work of finding potentially dangerous cracks is up to the team of experts here who painstakingly analyze the imagery sent down from the shuttle's 50-foot inspection boom.
Both spacesuits on Discovery have been checked out for transfer to the station, and the crew is preparing to begin transferring supplies and hardware to the station in less time than they experienced in training. There will only be three spacewalks during their stay instead of four, and the docked period will be correspondingly shortened, because Discovery must leave by March 25 to make way for the arrival of a Russian Soyuz with the first members of the next station crew.
Shuttle surface photo: NASA
