FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Atlas
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1971
1971 - 0230.PDF
FLIGHT International, II February 1971 215 of the drogue. The most probable solution was that moisture had frozen to form a wedge of ice and that this had later melted. For the next 19hr the astronauts flew on while con trollers pondered. The problem was whether this failure could occur again during the mission, as when Antares rejoins Kitty Hawk after lift-off from the lunar surface. Should this occur, a rather perilous EVA would be required between two unsecured spacecraft in order to get Mitchell and Shepard back into the command module. The alterna tive would have been simply to eliminate the Moon landing and devote the mission to photography from lunar orbit. But at the end of the 20hr "think session," with the risks weighed and rewards considered, go-ahead was given for Moon landing. Meanwhile, the S-IVB had been manoeuvred away from the Apollo spacecraft by ground controllers and aimed directly at the Moon. Because of the launch and docking delays, this took place lhr 45min late at T + 6.19hr. It was to crash on to the Moon early on February 4, shortly after Apollo entered lunar orbit. The seismic shock of the 25,0001b rocket hitting the Moon at 5,690 m.p.h., 9,027km/hr is equivalent to that of 11 tons of TNT. The resulting shock wave was to be measured on the seismo meter left behind by the crew of Apollo 12. Nicknamed "Big Moose" by Roosa, the spent rocket was travelling its own course 1,000 miles, 1,600km from Apollo and tumbling end over end every 4.5min. From then on things went better. At 2211 on Monday the spacecraft passed the half-way mark, 119,372 miles, 192,108km from Earth, travelling at 3,403 m.p.h., 5,477km/hr. The spacecraft was established in its "barbecue" or passive thermal control mode, in which it rotates slowly to provide a constant exposure of all surfaces to the Sun. Without this, one side of the space craft would roast while the other froze. The manoeuvre was halted only for course corrections and navigation fixes. A third mid-course correction proved unnecessary and was cancelled, enabling some valuable leeway to be made up on the unscheduled use of extra fuel during the docking problem. The astronauts have been very much less talkative than the crews on previous nights—so much so that, at one point, Houston called up to check that they were still there. One subject that did stimulate conversation was the presence of the optical flashes experienced by most of their predecessors. These are thought to be the result of penetration of the optic nerves by cosmic rays, and a positive aproach was taken towards studying them in preparation for this flight. Shepard, Mitchell and Roosa were all taught a preselected range of terminology in describing the flashes, in order to help scientists recreate them on Earth. The flashes were so strong that Roosa reported an ability to see them almost immediately after shining a torch directly into his eyes. Mitchell described three different types of flash that he had seen as resembling, respectively, a star, a streak and sheet lightning. Shepard agreed that the mysterious lights "do seem to be random in a showering-type pattern. They are visible in a darkened cabin within a very few minutes of turning the lights out, perhaps in as small a time as two minutes." Dr Richard Ebenson, a radio-biologist at Houston MSC, observed that "up to now there has been no evidence that the light flashes have produced any injury—nothing detectable. For short missions, therefore, we don't expect there to be any harm. Our only concern at present would be with longer missions." Two other minor problems had occurred by this time to brighten the voyage even further. On Tuesday, February 2, the oxygen flow in Kitty Hawk was found to be slightly higher than normal. The fault was rapidly traced to an open valve in the waste management system and soon corrected. The other problem was the failure of Shepard's cardiac sensor during launch. It came loose, so that no heart measurements were obtainable until Shepard replaced it with a spare, 90min after lift-off. At 0648 GMT on February 4, more than 81.5hr after launch, communications were cut off as the spacecraft curved round behind the Moon. A 6min burst from the main engine slowed it into an initial elliptical orbit varying from 70 miles, 112km to 193 miles, 310km above the sur face. At 0720, "Big Moose" crashed on the Moon, 9min ahead of schedule but, because of the docking delay, 150 miles, 240km off target. Its original target was a point 295 miles, 472km west of the landing site and 190 miles, 305km from the seismometer. It ended up some 220 miles, 354km south-west of Fra Mauro and only 150 miles, 240km from the seismometer. Meanwhile, back in the spacecraft, the astronauts travelled on for another two orbits and had lunch. After 4.5hr, an unprecedented manoeuvre was carried out when another short burst of the engine, lasting 21 sec, dropped the spacecraft into an orbit of which the high point was now 70 miles up but the low point was only 50,000ft, 15,000m above the surface. The object of this exercise was to minimise the lunar module's descent distance so that more fuel would be available for terminal manoeuvres over the landing site. The hilly nature of the terrain makes this the most difficult landing so far. Although the orbital manoeuvre offered the LM only an extra 15sec of hover time, those few seconds might have proved invaluable. For the next 17.5hr the spacecraft continued circling the Moon at this height. Emerging from the darkened While the astronauts struggled to dock in space, engineers at Houston experimented with simulators in unsuccessful attempts to identify the problem. The three small capture latches at the probe tip, below, failed to operate
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
