Aug 20 1975
From The Space Library
Viking 1 was successfully launched at 5:22 pin EDT from Eastern Test Range's Launch Pad 41 on a Titan III-Centaur launch vehicle. The launch, first scheduled for 11 Aug., had been postponed until 14 Aug. to replace a faulty thrust-vector control valve on the launch vehicle [see 11 Aug.]. A second delay had occurred when the spacecraft's internal batteries had discharged to 9 volts, well below safe limits [see 13 Aug.]. The spacecraft, Viking A, had been removed from the launch vehicle and replaced by Viking B. The range safety officer had issued a waiver of standard procedures and permitted removal and installation of the spacecraft without detanking and depressurizing the launch vehicle, thus allowing the launch to be rescheduled for 20 Aug.
Viking 1, consisting of a 2360-kg orbiter attached to an 1180-kg lander, was placed in a trajectory to Mars within the designed 3-sigma limits. Nearly 35 min after trajectory insertion, the Centaur stage separated from the spacecraft. The solar panels were deployed and oriented toward the sun, and the biocap-a container used to hermetically seal the lander while in earth's atmosphere-was jettisoned. On 27 Aug. at 2:30 pm EDT a trajectory-correction maneuver targeted the spacecraft to its Mars orbital insertion point. By 28 Aug. all systems aboard the spacecraft were operating normally and in a cruise mode. Travel time to Mars was estimated at 10 mo, with a possible Mars landing on 4 July 1976, the height of the U.S. Bicentennial. A second spacecraft, Viking B, had been scheduled for a 1 Septa launch to arrive at Mars in 12 mos.
The Viking missions supported NASA's planetary program goals of exploring the solar system and gaining 'knowledge of its origin and evolution, and of the origin and evolution of life and of the dynamic processes that shaped man's terrestrial environment. Specific purpose of the two Viking missions was to increase knowledge of Mars by making observations from Mars orbit and by direct measurements in the atmosphere and on the surface, with particular emphasis on biological, chemical, and environmental data on past or present existence of life on the planet.
Viking 1 was targeted to land in the Martian equatorial region, in a very low area resembling the fluvial plain of a dry river bed-an ideal site to search for organic material. Alternate sites for both Viking landers had been selected and there would be some flexibility until insertion into Mars orbit, after which the available band of landing sites would be narrowed by orbital geometry. Once in orbit, the orbiter would survey prospective landing sites; when the decision on where to land had been made, retrorockets would separate the lander from the orbiter and the lander would descend to the surface, sequentially braked by its aeroshell's drag, by a parachute, and finally by its retrorockets. After landing, the science instrumentation would be activated and exploration would begin; data would be transmitted back to earth by the lander radio or through a radio-relay link with the orbiter.
The orbiter's main body, an octagonal ring 46 cm high with alternating 140- and 51-cm sides, consisted of 16 modular compartments. The entire structure was 10 m across the tips of the extended solar panels and 3.3 m high from the lander attachment points to the launch vehicle. Besides propulsion, navigation and control, communications, power, computer, and data-storage subsystems, the orbiter carried its science instrumentation mounted on a scan platform that could move with 2 degrees of freedom. The three science instruments were twin high-resolution, slow-scan TV cameras; an infrared atmospheric water detector; and a high-resolution infrared thermal mapper for detecting surface-temperature variations.
The lander was a six-sided aluminum and titanium box 46.2 cm deep and enclosed top and bottom by cover plates; it measured 3 m wide and 2 m high from the footpads to the top of the S-band antenna. The six sides measured 109 cm and 56 cm alternately, with the three landing legs attached to the three narrower sides. The three retrorockets were mounted at 120° intervals on the lander; generating up to 2838 newtons (638 lbs) thrust, they would be ignited at an altitude of 1220 m to slow the lander's descent from 222 kph to 9 kph at landing. Four small engines provided attitude control.
In addition to subsystems for thermal control, power, and communications, the lander carried six instruments: twin scanning TV cameras, a sophisticated biology laboratory, a gas chromatograph mass spectrometer, an x-ray fluorescence spectrometer, a meteorology instrument, and a seismometer. Used with numerous temperature, pressure, and magnetic sensors, the instruments would perform entry, landed, and radio experiments.
NASA's investigation of Mars had begun in 1964 with the launch of Mariner 4. That spacecraft's flyby on 15 July 1965 had revealed the planet to be moonlike with a dry, barren, cratered surface showing little evidence of wind or water erosion and no magnetic field. The better instrumented Mariners 6 and 7 that flew by the planet during the summer of 1969 reported a chaotic view of jumbled ridges and valleys unlike anything found on the earth or moon. The spacecraft also showed wide featureless expanses where craters had been somehow eroded, suggesting that Mars had been geologically active. Mariner 6 and 7 photographs showed a thin layer of snow-probably carbon dioxide-and instruments measured a thin atmosphere of mostly carbon dioxide.
High-quality photographs from Mariner 9, placed in Martian orbit on 13 Nov. 1971, provided evidence of fluid erosion, glacial action, and volcanoes. The Viking missions had continued the Mariner explorations of Mars.
Viking was managed by Langley Research Center under overall direction of NASA's Office of Space Science; LaRC also had management responsibility for the lander system designed and built by Martin Marietta Corp. Jet Propulsion Laboratory designed and built the orbiter system. The Titan-Centaur launch vehicle was the responsibility of Lewis Research Center; LaRC managed launch and flight operations executed by Martin Marietta, Kennedy Space Center, and JPL. Goddard Space Flight Center was responsible for tracking and data systems, and JPL managed the mission control and computing center system. (NASA MORs S-815-75-01102, 1 Aug 75, 28 Aug 75, 16 Sept 75; NASA Release 75-183; LaRC Launch and Mission Operations Status Bulletins Nos 9-11; Viking: Mission to Mars (NASA SP-334); W Post, 18-22 Aug 75; NYT, 18-22 Aug 75)
Doctors had rechecked x-rays of Apollo-Soyuz Test Project astronaut Donald K. Slayton's lungs taken before the 15 July launch and found that they also had shown a shadow revealed by postflight x-rays, Dr. Arnauld E. Nicogossian, NASA's ASTP physician, said at a Johnson Space Center press briefing. Dr. Nicogossian said that the spot had not been noticed before because the x-rays were difficult to read and the spot had been covered by normal vasculature and bony structure. Only a 6 Aug. tomogram [see 25 Aug.] had verified that the shadow was a lesion. Dr. Nicogossian said the nitrogen tetroxide inhaled by the ASTP astronauts during reentry [see 15-26 July] had not been shown to have caused or increased the size of the lesion.
Dr. Nicogossian added that, if cancer were diagnosed during the surgery, the usual medical procedure was to remove a part of the lobe, but he did not think that would prevent Slayton from flying in the future.
Slayton said that he felt "pretty damn lucky" that the lesion had been discovered when it was. "This thing could have been discovered before the flight.... And I could have easily gotten jerked off the flight, so that would have been bad. Secondly, if we hadn't had the gas in the cockpit on reentry, . . . [the doctors] could very easily not have picked this thing up until my next annual physical which is 6 or 8 months off." Then it would have been a "lot tougher" to fix.
Slayton, one of the seven original U.S. astronauts, had been grounded in 1962 because of an erratic heart rate, first detected in 1959, but had been returned to flight status March 1972 in time for assignment to ASTP. He told the briefing that he hoped to be out of the hospital within 7 days and back to work in 2 wk, and on flight status again within a month. (Transcript, ASTP PC-63, 20 Aug 75)
NASA announced that the U.S. tour by the five Apollo-Soyuz Test Project crewmembers had been postponed to 13 Oct. because of astronaut Donald K. Slayton's scheduled lung surgery. The crew's tour of the U.S.S.R., scheduled to begin 22 Sept., would continue on schedule [see 15 Aug.]. (NASA Release 75-236)
Lt. Col. Michael Love successfully completed the 28th flight of the X-24B lifting body, making its second and final runway landing [see 5 Aug.] at Flight Research Center. The purpose of the flight was to land on a concrete runway, survey body pressure, study a left hand fin tuft, check out the thermal protection system, and perform stability and control maneuvers with the rudder bias at 5° toe-out. Launched from a B-52 aircraft at 13 700 m, Col. Love ignited the vehicle's rocket engine and the X-24B reached a speed of mach 1.53 and an altitude of 21 900 m before engine shutdown and unpowered glide and landing.
Flights of the 11-m delta-shaped vehicle were part of a joint NASA Air Force program to study transonic flight characteristics of an aerodynamic shape that could be the forerunner of future hypersonic cruise vehicles. (X-24B fit rpt, NASA Prog Off; FRC Release 25-75)
The Large Area Crop Inventory Experiment (LACIE), a low-budget cooperative NASA-Department of Agriculture-National Oceanic and Atmospheric Administration program designed to assess U.S. wheat crop yields and to forecast production, could develop into a worldwide crop program, J. F. Ter Horst reported in the Los Angeles Times. If elevated in status and budget priority by President Ford, LACIE could accurately measure a worldwide grain feast or famine each year, identifying regions of big harvests and potential shortages, vital in allocating world food supplies to meet the needs of growing world population. Ter Horst quoted an advisor of President Ford as saying that, if the LACIE system were in worldwide operation, "we would know what the Russian grain crop was likely to be, what they would be buying, and just how much of our crop we could afford to sell them." Ter Horst added that intelligence sources indicated the Russians had already measured U.S. crops by satellite. "If true, that could explain the confidence of Russian grain-purchasing moves this year. It also indicates an accelerated U.S. political need to play catch-up in this phase of the space race." (Ter Horst, LA Times, 20 Aug 75)
A Today editorial had commented on the planned Viking flight to Mars: "Success of the Viking flight could mean additional Congressional support for more sophisticated flights in the future. . . It will be almost another year before we will have the answers to the Viking experiments. . . At that time, we will be celebrating the 200th birthday of our country-and what better way to celebrate the birth of one nation than with the discovery of another?" (Today, 20 Aug 75)
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
