Dec 23 1975
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(New page: Pioneer 11, about a third of the way on its course toward Saturn, had successfully completed its riskiest course-change maneuver in response to signals from earth, 458 million km dista...)
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Pioneer 11, about a third of the way on its course toward Saturn, had successfully completed its riskiest course-change maneuver in response to signals from earth, 458 million km distant. Controllers at Ames Research Center ceased communications with the Pioneer for several hours, giving the spacecraft time to command itself into a change of position, fire its thrusters, and reposition itself with antenna pointing back to earth. The maneuver increased spacecraft velocity by 108 km per hr, to ensure that Pioneer would have a choice of approach as it neared Saturn: between the rings and the planet, or under the rings and upward outside them. Recent tests had shown the onboard camera working well; Pioneer 11 had been scheduled to take the first closeup pictures of Saturn and its rings upon arrival at the planet in 1979. If its course had been set inside the rings, Pioneer 11 should be able to look closely at Saturn's sixth moon, Titan, which is larger than the planet Mercury. (NASA Release 75-319; ARC Release 75-69)
The Pentagon, checking out reports of Soviet laser devices that had blinded U.S. reconnaissance satellites, had found the reports to be wrong, said new Secretary of Defense Donald H. Rumsfeld at his first press conference since taking over from James R. Schlesinger a month ago. Rumsfeld declined to say how it had been determined that intelligence reports were wrong, but said: "After examination, any implication that the activity that was reported... did in fact exist was not correct." He said it was clear there was no violation of any arms control agreement, nor any evidence to support the laser report, which he sought to portray as press speculation. (W Star, 23 Dec 75, 6; NY News, 23 Dec 75, 2)
The National Oceanic and Atmospheric Administration had developed a new remote-sensing technique to "see" nitrogen oxide in the stratosphere, permitting scientists for the first time to calculate the actual rate at which the nitrogen compounds destroy stratospheric ozone. Much of the work on the ozone cycle had been theoretical, based on computer models and laboratory tests; seasonal variations in the stratosphere at high latitudes, revealed by spectrometers on jet aircraft, had not been predicted by theory, which meant that the computer models had not provided close simulation. The new technique, using a spectrometer to measure the light spectrum and isolate that portion caused by nitrogen dioxides, would permit routine checks on daily, seasonal, and latitudinal variations in the content of the stratosphere. The method would be applied by small automated instruments run by minicomputers at NOAA stations in Alaska, Samoa, Hawaii, and the South Pole, and at the Air Force base in Greenland. (NOAA Release 75-220)
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