HOUSTON, July 24, 1969 (UPI) -- Thunderstorms in the main recovery area forced a last minute change in the landing area of Apollo 11, heading for a Pacific Ocean splashdown today that will be witnessed by President Richard Nixon.
"The weather is globbering in at our targeted landing point due to scattered thunderstorms. We don't want to tangle with one of those," ground control told Neil Armstrong, Edwin Aldrin and Michael Collins late Wednesday.
Officials gave the space fliers new instructions that stretched the landing area to a point 247 miles south east of Johnston Island, rather than 497 miles southeast of the island. Splashdown time is 12:49 a.m. (EDT).
The change posed no great problem for the crew since the flight path can be stretched by utilizing the lift capabilities built into the design of the spaceship.
Officials didn't want to take a chance with anything as unpredictable and potentially violent as a Pacific thunderstorm that could possibly keep the rescue helicopters grounded at a crucial moment, or kick up such large waves that the astronauts became seasick once on the water.
At midnight (EDT) the Columbia command ship was about 84,448 miles from earth and rocketing homeward at 4,794 m.p.h.
Its speed will continue building until it blasts into the heavy earth atmosphere at 24,667 m.p.h., trailing a fireball that should be clearly visible to Nixon aboard the recovery carrier USS Hornet.
During their homewardbound flight Wednesday night the astronauts beamed to earth a final, dramatic television show in which they told what the trip to the moon had meant to them.
Each of the astronauts appeared before the camera during the 15-minute telecast and paid tribute to the scientific and engineering teams on the ground that have made the flight a success.
Scientists said the seismometer set up on the moon by Armstrong and Aldrin Wednesday had radioed back reports of either a moonquake or the jolt of a meteoroid hitting the lunar surface.
A moonquake would indicate the moon, like earth, is a live celestial body with a hot core producing stresses below its surface.
Dr. Garry Latham, one of the nation's leading geophysicists, leaned toward the theory that a quake, rather than a meteoroid, caused the vibrations. "In fact," he said. "I'm going to claim a case of champagne from a colleague in California on a wager as to whether or not there are moonquakes."
The event was recorded by a series of wiggles on a graph at the Manned Spacecraft Center, a quarter million miles from the moon.
"If that were a meteoroid impact," Dr. Latham said, "it would by the equivalent to an explosion of a few kilotons (of TNT), and that would be a very large meteoroid which is rare and we would be very lucky to get it so soon."
"So for that reason I feel tentatively it is a moonquake."
Dr. Eugene Shoemaker, principal investigator for Apollo 11's geological findings, agreed with Latham. He said if a meteoroid impact caused the vibrations it would have had to be something like a 10 ton projectile striking the moon at 45,000 m.p.h.
"And this is not likely to happen but three or four times a year," Shoemaker told UPI. "It's too energetic to be likely that you would get so big a bang right off."
Latham said before the instrument was placed on the moon Sunday night the moonquake question was among the top lunar mysteries. He said scientists simply did not know whether they existed.
It will be shortly after dawn (5:49 a.m.) Honolulu time when Apollo 11 and its precious cargo of astronauts and 50 to 60 pounds of lunar rock and soil samples hit the water.
Because of the possibility the spacemen may have picked up some strange germs while trampling the lunar surface, Nixon's greeting to the astronauts will be through the closed window of a 35-foot-long isolation trailer where the astronauts will be taken as soon as they step aboard the carrier.
The trailer then will be flown to the Houston Manned Spacecraft Center where they will remain in isolation an additional 15 days while doctors determine whether they have brought back any moon bugs that could prove dangerous to man.