Apollo 13 descends on its parachutes towards splashdown. Photo: NASA/JSC

Re-entry day -- the climax of this 7-day space drama -- started quietly. But steady confidence changed to nervous tension when the Commander, Jim Lovell, who's now clocked up 30 days in space, made what was probably his biggest mistake in all that time.

Clearly cold and jaded, with only three hours' sleep behind him, he punched up the wrong computer programme for the final course correction. It would have fired the main descent engine instead of the little 100 lb thrusters. Mission Control here spotted it at once, and no harm was done. But there were five hours still to go.

Minutes later, the astronauts' boss, Deke Slayton, was at the mike, telling the crew that they must break open their medical kit and take dexedrine tables - stimulants to sharpen up their reactions. Until then, they'd all refused to take even an aspirin.

The point was, everything possible had by then been done on the ground. It was now up to the crew. When the disaster struck, over three days ago, everyone thought it had happened at the worst possible moment, since the spacecraft was nearly a quarter million miles from earth.

As it's turned out, it was that that saved the astronauts' lives. For it gave Mission Control the time, by running the simulators non-stop, to work out re-entry techniques barely dreamed of.

Apollo 13 splashes down in the Pacific Ocean. Photo: NASA/JSC

One hour, 15 minutes before splashdown, Lovell, Haise and Swigert shut themselves into the dead Command Module and jettisoned their Lunar lifeboat, Aquarius. "Farewell, and thankyou" and "She sure was good ship" we heard them saying as they watched it drift apart.

After that, everyone could relax. From then, it was a familiar re-entry procedure. Here at Mission Control even the journalists found time to cheer when Apollo 13, supported by its three huge parachutes, suddenly appeared on the TV screens, a mere four miles from the Recovery carrier, USS Iwo Jima.

Within half an hour of the astronauts stepping aboard, Dr Tom Paine, head of NASA, was announcing that even if Apollo 13 was a failure, there had never been a more prideful moment in the history of NASA than that final splashdown.