Astronauts and flight controllers crowd around the guidance console as the drama unfolds. Photo: NASA/JSC

Glynn Lunney at Mission Control described it as "the longest night in the space programme". For hours after the explosion we've been listening to the exchanges between the crew and Mission Control, trying to identify what it is that the astronauts can see venting into space. But both the crew and Mission Control reported their consoles showing rapidly falling oxygen pressures. Fred Haise was first ordered to shut down two fuel cells, and then the third and last. Once shut down, they can't be reactivated. His voice was bleak as he queried -- but obeyed -- Mission Control's confirmation that the Command Module's last source of life-giving power and oxygen was to abandoned.

Use as little power as possible, said Houston, as the crew retreated into the Lunar Module. Lights were put out. Swigert sat in the dark using a flashlight. On the ground, back up crews were already in the simulators, said Houston reassuringly. They were trying to work out control modes and looking at consumables. Meantime, could the crew look out of the window and try to identify some stars to get a spacecraft alignment ?

"Right now" said Lovell, "It's pretty dark. "There are a thousand or so foam stars out here, left over from some of the debris [from the explosion]. It's hard to discern what's real and what's not real."

Five hours after the crisis began came the first briefing on a survival plan -- prefaced by a warning that the situation in the Lunar Module was "water critical -- so use as little as possible". Water is not only essential for drinking, but for air conditioning and cooling the electronic system.

It's the grimmest situation so far in America's space programme. But though the atmosphere here is undoubtedly very tense, the exchanges between Mission Control, Jim Lovell and his crew have been unwaveringly calm and steady.

There are 70 hours to go before a possible safe splashdown.