Sep 20 1976
From The Space Library
Aviation Week & Space Technology magazine reported that the first hitch in operations of the Viking 2 lander-trouble with its digging arm-had been solved: the problem turned out to be in a micro switch. Ground control at the Jet Propulsion Laboratory in Calif. had commanded the lander's computer to ignore signals from the malfunctioning switch in future digs. If the corrective commands freed the arm for duty, the experiments needing soil samples would begin receiving them and results would become available within a week or 10 days. Viking 2's lander cameras had returned excellent pictures of the Utopia terrain around the landing site; the meteorological experiment was collecting and returning weather data regularly; and the seismometer (whose parallel on Viking 1 was never uncaged) was ready to monitor marsquakes, the magazine said. (Av Wk, 20 Sept 76, 25, 58-61)
The council of Intersputnik-the International Organization for Cosmic Telecommunications-ended its fifth meeting in Berlin after 4 days of deliberations. Attending were delegations from Bulgaria, Hungary, the German Democratic Republic, Cuba, Mongolia, Poland, Czechoslovakia, and the USSR; also attending were observers from the Intl. Organization for Radio and Television (OIRT), Intercosmos, and the Standing Commission for Post and Telecommunications (CEMA). The meeting adopted documents on the use of technical installations for transmitting TV, radio, telephone, telegraph, pictures, and data by satellite. (FBIS, ADN Intl. Service in German, 20 Sept 76)
Evaluation of data and pictures from a dendrite-remelting experiment flown in Dec. 1975 on a space processing applications rocket (SPAR 1) confirmed the belief that space processing could produce better materials than was possible on earth, NASA announced. The experiment, one of nine sent to a 225-km altitude for about 5 min of near weightlessness, included a camera to record solidification of aluminum chloride solution in a transparent vial in the absence of gravity. No fluid motion was detected in the liquid, which solidified uniformly without the formation of crystals (dendrites) that broke off and settled to the bottom of the solution in a control experiment on earth. This experiment was the first in which scientists had viewed the process of solidification under weightless conditions, said the co-investigators, Carolyn Griner and Dr. Mary Helen Johnston of Marshall Space Flight Center. Controlling the crystalline structure of materials would enable scientists to make them uniformly strong to meet specific needs. (NASA Release 76-159; MSFC Release 76-167)
Nine sites for the world's first solar electric-power plant had been proposed by utility companies and government units in the U.S. in response to a request in July 1976, the Energy Research and Development Administration announced. Sites suggested were in Arizona, California, Florida, Mississippi, Puerto Rico, Rhode Island, and Texas. The agency planned to complete an evaluation and negotiate a contract with the selected proposer early in 1977; the selected proposer would become a partner with ERDA in constructing and operating a plant to generate electric power from high-pressure steam produced by concentrated power from the sun. Power from this pilot plant would be distributed by the utility to its customers; the plant would produce 10 Mw (10 000 kw) under optimum full-sun conditions, enough to supply a community of 10 000 population. Construction of the plant would begin in 1978 and reach completion in 1980, at an estimated cost of $100 million. (ERDA Release 76-294)
20-25 September: The committee on planetary and lunar exploration of the Space Science Board began meeting 20 Sept. at the Calif. Inst. of Technology to consider proposals for future space exploration, including a radar mission to Mars to determine the thickness of the ice at the polar caps and investigate the terracing of the planet as a clue to past climate. Terrace edges in both polar regions had been found to lie along concentric circles centered close to, but not identically with, the poles. Scientists had suggested the terraces were formed when Mars was spinning around a slightly different axis under climate conditions other than those at present. A change in the Viking 1 orbiter's path to take over communications relay for the Viking 2 lander would free the Viking 2 orbiter by 24 Sept. to proceed with a polar-observing mission.
The Viking 2 lander's pyrolytic-release instrument, which had been directed to look for evidence of photosynthesis activity in a dry Mars soil sample in the dark to avoid ambiguity, had returned an ambiguous reading, said Dr. Norman H. Horowitz of the Calif. Inst. of Technology, who designed the instrument. The count of radioactive molecules released during the analysis was 21 per minute, far less than the 96 per minute counted in the first similar assay by the Viking 1 lander, but more than the 15 counts per minute the instrument would show in the absence of photosynthesis. The puzzled scientists planned another sampling, this time with a moistened sample under a sun simulator, which had been omitted from the first run to prevent overheating the Viking 2 instrument, working in a location warmer than the Chryse area tested by Viking 1.
Although neither of the Viking landers had turned up more than a suggestion of life, Viking 2 had confirmed the presence of water on Mars, and more than had been expected, project scientists announced at a JPL news conference 22 Sept. The permanent northern polar cap was found to be composed entirely of frozen water, not of frozen carbon dioxide as had been thought. A thin layer of dry ice covering the polar caps during most of the Martian year had suggested that both caps consisted of frozen carbon dioxide. Two Viking 2 orbiter measurements that led to the discovery were the unusually high water-vapor content in the atmosphere over the northern pole, and the average-surface temperature readings on the icecap, which were too warm for frozen carbon dioxide to exist. Dr. Hugh Kieffer of UCLA predicted that a survey of the south polar cap would find it also made entirely of water ice. The new evidence suggested that, when first formed, Mars might have had twice as much water as the earth had at a similar period in its development; even now, scientists described Mars as "a planet-size iceberg." Other Viking instruments had detected traces of krypton and xenon in the Mars atmosphere. This discovery was the first clue that the planet once had a considerably denser atmosphere that could have supported liquid water and even rainfall. Dr. Gerald Soffen, chief Viking scientist, said that the krypton finding was a "major marker" that would permit deductions about the origin of the Mars atmosphere.
On Saturday, 25 Sept., mission scientists at JPL were "relieved" to see photographs transmitted by Viking 2 showing that the lander had followed an order radioed from earth to dig a trench and dump the soil sample into the organic analyzer to screen it for 2 wk in a search for microorganisms. (Mission Status Bulletin 44; NYT, 21 Sept 76, 18; 26 Sept 76, 5; W Post, 23 Sept 76, A-2; 24 Sept 76, A-2; 26 Sept 76, A-6; W Star, 23 Sept 76, A-3; 26 Sept 76, A-14)
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