James A. Lovell, Jr., Commander... Fred W. Haise, Jr., Lunar Module Pilot... John L. Swigert, Jr., Command Module Pilot.
SPACECRAFT--Hey, we've got a problem here.
Thus, calmly, Command Module Pilot Jack Swigert gave the first intimation of serious trouble for Apollo 13--200,000 miles from Earth.
CAPSULE COMMUNICATOR--This is Houston; say again, please.
SC--Houston, we've had a problem. We've had a Main B bus undervolt.
By "undervolt" Swigert meant a drop in power in one of the Command/Service Module's two main electrical circuits. His report to the ground began the most gripping episode in man's venture into space. One newspaper reporter called it the most public emergency and the most dramatic rescue in the history of exploration.
SC--And we had a pretty large bang associated with the caution and warning here.
Lunar Module Pilot Fred Haise was now on the voice channel from the spacecraft to the Mission Control Center at the National Aeronautics and Space Administration's Manned Spacecraft Center in Texas. Commander Jim Lovell would shortly be heard, then again Swigert--the backup crewman who had been thrust onto the first team only two days before launch when doctors feared that Tom Mattingly of the primary crew might come down with German measles.
Equally cool, the men in Mission Control acknowledged the report and began the emergency procedures that grew into an effort by hundreds of ground controllers and thousands of technicians and scientists in NaSA contractor plants and On university campuses to solve the most complex and urgent problem yet encountered in space flight.
SC--We've got a Main bus B undervolt, now, too... Main B is reading zip (zero) right now.
CAPCOM--We'd like you to attempt to reconnect fuel cell 1 to Main A and fuel cell 3 to Main B.
SC--Okay, Houston... I tried to reset, and fuel cells 1 and 3 are both showing zip on the flows.
SC-- Houston, are you still reading 13?
CAPCOM--That' s affirmative. We're still reading you. We're still trying to come up with some good ideas here for you.
SC--Let me give you some readings... Our O2 (oxygen) cryo number 2 tank is reading zero--did you get that?
CAPCOM--O2 quantity number 2 is zero.
After peaking briefly just before the bang, pressure in one of the two cryogenic (super-cold) oxygen tanks, back in the Service Module, had dropped to zero in eight seconds. These oxygen tanks, with the companion cryogenic hydrogen tanks, feed the three fuel cells that generate the spacecraft's electrical current, provide breathing oxygen, and produce water.