Space Station's Solar Power Compromised by Balky SARJ Unit - UNDUE VIBRATIONS, POWER SPIKES AND GRIT GIVE NASA PAUSE

摘要

Since last October, NASA engineers on the ground, as well as International Space Station (ISS) and shuttle Discovery astronauts, have been working to indentify and rectify an ongoing problem with one of the two solar array panels that power the station's energy system. The area of concern is one panel's two 10-foot-wide bull gears, fitted with two redundant-drive motors, or drivelock assemblies (DLA). Together, they comprise one SARJ - or solar alpha rotary joint - in the power truss that serves to direct the massive starboard solar panels towards the sun. Only one DLA is needed at any time to power the outboard bull gear. The other panel is problem-free. While at this writing a root cause remains elusive, the problem does not present any imminent danger to the crew or station, according to NASA. That's because despite what NASA SARJ recovery team leader Kevin Window characterizes as a "major anomaly," both solar panels can still be maneuvered, if necessary. In other words, the motor and/or bearings that power the panel in question have not seized and are therefore operational, if only manually for the time being.