Jun 11 1976
From The Space Library
A 2-wk experiment to observe the Gulf Stream about 580 km east of NASA's Wallops Flight Center used a combination of spacecraft, aircraft, and water craft to check the ability of remote sensors to measure the magnitude and boundaries of the Gulf Stream from space. Gulf Stream measurements would aid in planning more effective use of coastal waters, as in cooling nuclear power plants, or in constructing offshore drilling rigs or airports located on manmade islands. Scientists also wanted more data about the Gulf Stream, which carries heat energy that influences the global balance of energy in the atmosphere and the ocean, affecting weather and climate as well as coastal water movement, besides carrying nutrients important to the fishing industry. Traditional methods using closely spaced ship stations or buoys to obtain data had proved inadequate for studying fast-changing or large-scale phenomena. Satellite measurements used in the experiment included infrared signatures that identified the Gulf Stream boundary from space photographs. A precision altimeter on NASA's Geos 3 (Geodynamic Experimental Ocean Satellite) measured surface deviations in the ocean within 20 cm, from which velocity of a current could be calculated; the experiment also used the National Oceanic and Atmospheric Administration's NOAA 4 weather satellite. A C-54 research plane from Wallops carried instruments on 3 flights to measure the current by observing wave interactions; surface measurements were taken by the research vessel Advance II from Cape Fear Technical Institute at Wilmington, N.C., manned by ocean scientists from N.C. State University at Raleigh. The project was part of a scientific research task directed by NASA Hq's Office of Applications. (NASA Release 76-115; WFC Release 76-7)
Detente, to be meaningful to U.S. scientists, must include progress toward more intercommunication and openness, said Dr. Bruce Murray of CalTech and Merton E. Davies of RAND Corp. in an article in Science magazine. Noting that for nearly 2 decades the space program of the U.S. and the USSR were bound together through rivalry, competition, and most recently-cooperation, the authors found it appropriate upon completion of the Apollo-Soyuz mission to review relationships between the 2 countries and focus on areas of possible common interest. The interrelationship with the Soviet space effort had stimulated both societies and had influenced the character of individual programs, the authors said. Future joint activities could take three forms: data exchange, cooperative experiments, and joint operations. Examples cited were exchanges of weather-satellite pictures, lunar soil and rock samples, and limited data on Mars obtained during simultaneous missions in 1971; the U.S. biological experiments carried on Cosmos 782, launched and returned to earth in 1975; and the joint operation of Apollo-Soyuz, which demonstrated the practicality of such missions despite differences in language, institutions, technology, and style. Joint scientific progress in space would depend on broader social objectives and activity, supported by popular enthusiasm for intellectual and generally human adventure, the authors said. (Science, 11 June 76, 1067)
The board of governors of the International Telecommunications Satellite Organization (INTELSAT) announced that, at its recent meeting in The Hague 19-27 May, it adopted a 10-m class Standard B ground station to supplement the Standard A station long the foundation of INTELSAT's global system. Currently, 114 Standard A ground stations with 30-m antennas were operating throughout the world, as well as 29 smaller stations used for domestic service, telemetry, tracking and control, monitoring, and limited telecommunications between 2 or 3 destinations. Broadest use of the Standard B station would be in developing countries that had limited telecommunications requirements. Under study for some years, the Standard B. station would use single-channel-per-carrier (SCPC) equipment that allowed routing of traffic on a circuit-by-circuit basis instead of in large groups or bundles, minimizing the capacity loss associated with smaller antennas; it also worked with voice activation, which would be mandatory, using satellite capacity for telephone service only when activated by voice signals. Adoption of the second standard for international service would mean a 40% drop in rates paid for use of the satellites, plus ability to route traffic to any ground stations equipped to receive the user's signals, with no restriction on the total amount of traffic. Previously, the drain on satellite power limited small ground stations to providing service to only 1 or 2 other points. (INTELSAT Release 76-17-1)
11-30 June: The scheduled Fourth of July landing of Viking 1 on the planet Mars was briefly complicated by 2 problems announced in the news media 11 June: a mechanical problem with a leaky valve in the Viking's fuel tank, and a threatened strike by about 200 technicians at a desert tracking station at Goldstone, Calif., one of 3 in the world that relayed signals to and from the Viking. Neither proved insuperable; by 18 June, John D. Goodlette, chief Viking engineer, was describing the mission as "shooting right down the pickle barrel." "If we do nothing to the spacecraft from here on out," he added, "we'd miss our target by less than 60 miles [95 km]." Washington Post staff writer Thomas O'Toole explained that the target was a spot about 9600 km from Mars, where the onboard braking engine would slow the spacecraft from about 14 200 kph to about 9600 kph, putting it into an elliptical orbit to survey possible landing sites.
Viking 1 would scan and map the surface for 2 wk; its cameras would photograph the prime landing site near an ancient rift valley, and other instruments would measure surface temperatures and search the Mars atmosphere for signs of water. The new orbit would bring Viking over the planned landing site once each 24.6-hr Mars day (called a sol). The 2 wk of photographs and measurements were needed so that scientists at Jet Propulsion Laboratory, where the flight had been directed since launch in April 1975, could choose the safest and most interesting spot for their 4-ton bird to alight. The landing attempt would be the first U.S. try at putting a spacecraft down on another planet; the USSR had made 5 unmanned attempts, 3 on Venus and 2 on Mars. The 2 Venera spacecraft had survived on the surface long enough to send back 1 picture each; the third crashed, One Mars spacecraft had crashed, and the other was blown over after it landed by winds clocked at more than 300 kph.
After Viking's braking engine was fired, the main job of flight directors would be to navigate it into a path where its orbit would be lowered again, with apogee reduced from about 19 000 km to 12 500 km. The firing was successful 19 June, and the Viking neared the end of a 690-million-km voyage that began 10 mo ago. William J. O'Neill of JPL said the precision of the flight could be likened to "shooting a basketball in Los Angeles and putting it through a hoop in Madison Square Garden in New York City." Viking was following a northeasterly path around Mars that would bring it within 1450 km of the planet's surface; flight directors planned a second maneuver to bring it still closer over an area 20°N of the equator, called Chryse, where Viking would attempt to land 4 July, selected as a good place to search for signs of life or fossilized life that thrived when a river flowed there a billion years ago. Harold S. Masursky of the U.S. Geological Survey, chief geologist for Viking, said that Chryse resembled California's Death Valley or the water-worn dry valleys of Nevada or Wyoming, where ancient rivers overflowed their banks millions of years ago to deposit alluvial soils on the valley floors. Rock and soil in the Chryse valley appeared red from millions of years of iron oxide deposits brought down by the river overflow; Masursky and his colleagues hoped that the red soils would contain organic molecules, signs of a once-existent life on Mars.
A photograph taken 19 June and released by JPL on Sunday, 20 June, showed the "awesome" Valles Marineris from about 360 000 km up parallel canyons south of the Mars equator that, if extended together on earth, would reach from Calif. to Penna. The smaller was about 3 km deep, 64 km wide, and 645 km long; the larger was 6 km deep, 96 km wide, and more than 3200 km long. (Arizona's Grand Canyon, largest on earth, is about 2 km deep, 21 km wide at its greatest breadth, and only 350 km long.) The northern hemisphere of Mars appeared covered with haze, which scientists said was probably from water vapor misting out of the cold surface as the sun warmed it during the longer summer days.
Successful firing of the braking engine at 1:25 pm EDT Monday, 21 June, put Viking 1 into a lower orbit so that its cameras could begin to photograph steep slopes, craters, boulder fields, and other potential obstacles. On 27 June, Viking project manager James S. Martin announced that the 4 July landing was off; pictures of the primary landing area showed "too many unknowns," and the site appeared too hazardous to risk landing without investigating other sites. As the Viking 1 cameras could not distinguish objects "smaller than a football field," objects as yet invisible could endanger the landing. However, as there was no assurance of any hazard-free area roughly 20 km by 100 km anywhere on Mars, some scientists had wanted to go ahead with the planned landing. Previous closeups taken by Mariner 9 were not as detailed as those from Viking, and dangerous details of the primary landing site became more obvious with photos from Viking 1 coming in more clearly.
The New York Times reported that the first alternative site was an area called Chryse Phoenicia, a basin about 30 km northwest of the original site; if that site appeared too rough, scientists would look at Tritonis Lacus, about 6400 km east of Chryse, although if this happened, the landing might be delayed until as late as the first wk of August. Project Manager Martin suggested delaying the Viking 1 landing, if it were not down by 25 July, until the Viking 2 (now 8 million km away) arrived in Mars orbit; possibly 2 Viking spacecraft might be orbiting simultaneously. JPL said flight tracking and control facilities there were insufficient to handle full operations of both spacecraft simultaneously, and a number of preorbital maneuvers for Viking 2 would be required starting about 27 July. John Noble Wilford said in the New York Times that the earliest possible Viking 1 landing would be 9 July, and other alternatives would take longer. Scientists, he said, were "dismayed by the rugged Martian terrain"-the primary landing area being heavily pocked with craters, steep escarpments, and a sprinkling of knoblike features probably remnants of erosion like that in the Grand Canyon.
On 28 June, Viking 1 photographed a site about 300 km northwest of Chryse-the "northwest territory"-after pictures of the prime site showed it to be far more rugged than expected; the scientists wanted a landing as close as possible to the original site because they thought it offered the best chance of finding signs of existing or fossil life. The alternate site would be somewhat flatter and safer, but less interesting scientifically, O'Toole said in the Post 29 June. Photographs released 29 June at JPL showed a plateau in the Chryse valley originally picked as the Viking 1 landing site, where a curving and rugged coastline at the plateau's base could have been formed only by an ocean-like surf. Pictures taken from an altitude of about 1450 km showed a crater with lava-flow traces more than 30 km wide, "a truly enormous scale" according to chief geologist Masursky. "The biggest lava flooding ... on earth are the basalt floods on Iceland, which are no bigger than a few kilometers across." Temperature changes mapped by Viking were also dramatic: instruments on Viking registered differences of more than 60°C (140°F) between day and night in the same parts of the planet. Dr. Hugh H. Kieffer, atmospheric scientist on the Viking team, said that the atmosphere on Mars was almost perfectly transparent to sunlight, as little water was present to absorb it; "whatever sunlight reaches the planet gets right to the surface, which then radiates the heat back to the atmosphere to warm it up." An instrument aboard Viking could tell when day broke on the Mars surface although it had no way of "seeing"; it measured water vapor in the atmosphere, and registered its presence when the sun warmed the permafrost that "literally pops [water] into the atmosphere when that sun hits the surface first thing in the morning," according to Dr. Barney Farmer of JPL. Besides surveying possibilities for its own landing, Viking 1 was photographing potential landing sites for Viking 2 to give scientists an idea whether they might have to shift sites for that spacecraft also. (W Post, 12 June 76, A-12; 19 June, A-3; 20 June, A-1; 21 June, A-9; 22 June, A-17; 28 June, A-3; 29 June, C-4; 30 June, A-27; NYT, 21 June, 10; 28 June, 17; Av Wk, 28 June 76, 14)
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