MISSION CONTROL CENTER  
STS-63 Status Report #2  
  
Friday, February 3, 1995, 1: 15 p.m. CST  
  
As the six astronauts on board Discovery sleep, ground controllers 
in Houston are continuing to prepare for Monday's rendezvous with 
Russia's Mir space station.  
  
Controllers are monitoring a leaky reaction control system thruster, 
but so far, the steering jet does not pose an obstacle to the 
rendezvous.  
  
Shortly after Discovery reached orbit, ground controllers informed 
the crew that a right aft reaction control system jet had developed a 
small leak. The thruster is losing between 1-2 pounds of propellant 
every hour, a manageable loss according to mission managers. 
Earlier indications showed a loss of 2-3 pounds. Temperatures on 
the thruster remain constant at about 54 degrees Fahrenheit. If the 
temperature drops below 40 degrees Fahrenheit, controllers may 
have to close a manifold that supplies propellant to the leaking jet.  
  
Closing that valve would preclude the use of another healthy 
maneuvering jet which is to be used for close-in maneuvering 
around Mir. In that case, Discovery would not Discovery would not 
maneuver any closer than 1,000 feet from Mir.  
  
Flight controllers continue to monitor the jet's status and to 
investigate options for further minimizing or containing the leak.  
  
Earlier today, Commander Jim Wetherbee executed the first of 
several maneuvering burns that will take place over the next few 
days as Discovery prepares to rendezvous with the orbiting Mir 
space station.  
  
Crew members also activated the Spacehab module and began 
working with the experiments housed inside. Twenty different 
experiments ranging from protein crystal growth to a robotics 
demonstration comprise the STS-63 Spacehab payload 
complement. The astronauts also conducted a photographic survey 
of Discovery's payload bay using the shuttle's robot arm.   
  
All other systems on board Discovery continue to function well as 
the orbiter circles the Earth every 90 minutes at an altitude of 189 
by 180 nautical miles.