Apollo 10 launched from KSC on May 18, 1969, at 16:49:00 UTC (12:49:00 EDT, local time at the launch site), at the start of a 4.5-hour launch window. The launch window was timed to secure optimal lighting conditions at Apollo Landing Site 2 at the time of the LM's closest approach to the site days later. The launch followed a countdown that had begun at 01:00:00 UTC on May 17. Because preparations for Apollo 11 had already started at LC-39A, Apollo 10 launched from LC-39B, becoming the only Apollo flight to launch from that pad and the only one to be controlled from its Firing Room 3.
Problems that arose during the countdown were dealt with during the built-in holds and did not delay the mission. On the day before launch, Cernan had been stopped for speeding while returning from a final visit with his wife and child. Lacking identification and under orders to tell no one who he was, Cernan later attested in his autobiography that he had feared being arrested. Launch pad leader Gunther Wendt, who had pulled over nearby after recognizing Cernan, explained the situation to the police officer, who then released Cernan despite the officer's skepticism that Cernan was an astronaut.
More background from Chaikin's A Man on the Moon: The Voyages of the Apollo Astronauts:
On the eve of Apollo 9’s spectacular success, Mueller, like others at NASA, was asking, why in the world send the entire Apollo spacecraft to the moon—with all the risks involved—and not try to land?
One reason was that Stafford’s lunar module, built before Grumman enacted a super weight-saving program, was too heavy to land. There was some talk of letting Stafford use Armstrong’s LM, the first one built that was light enough for a landing, and postponing Apollo 10 a month to allow the switch.
But some, particularly Chris Kraft, raised strong objections. There were too many unknowns, he said. His trajectory people didn’t understand the moon’s lumpy gravitational field well enough yet to predict what mascons would do to the paths of the orbiting command and lunar modules. Would they pull the lander off course for its descent to the surface? And while the astronauts explored the moon, would mascons pull the command module off course for the rendezvous ahead? NASA needed more navigation data from Apollo 10 before it could commit the next crew to a landing.
Furthermore, Kraft’s flight controllers needed experience in communicating with two separate spacecraft at lunar distance. Sam Phillips, the tough, exacting air force general who served as Apollo program director, listened to all sides of the argument and decided that the dress rehearsal was not only desirable, but crucial.
Tom Stafford agreed. He’d wanted the first landing as much as anyone else, but he wasn’t about to campaign for a mission he knew was beyond accomplishing. Now was the time to find the hidden unknowns and solve them, so that Apollo 11 would be able to concentrate on the landing itself.
And Apollo 10 wasn’t simply a repeat of Apollo 9 in a different place; new procedures were required for a rendezvous in lunar orbit. Stafford and Cernan would take their lander and descend to 50,000 feet above the lunar surface, where they would make a critical test of the landing radar. Then, from this close vantage, they would scout Apollo 11’s proposed landing site in the Sea of Tranquillity before rejoining Young in the command module. By any measure, the dress rehearsal was a grueling mission; it seemed to Stafford’s crew that they had more to do on Apollo 10 than all the others combined.
And they did almost KLUNK in lunar orbit, so the dress rehearsal was a good idea...
No comments:
Post a Comment