Aug 12 1977
From The Space Library
NASA launched the first high-energy astronomy observatory, HEAO-A, from ETR on an Atlas Centaur at 2:29am EDT into a near circular orbit with 456.3km apogee, 431.4km perigee, 93.5min period, and 22.75° inclination.
HEAO 1, nearly 19ft long and nearly 9ft in diameter, weighting 56261b at liftoff (including 29601b of experiments and an 8311b separation system), had a 6mo design lifetime but would carry enough consumables and orbit at an altitude to allow extension of its mission up to lyr. It would operate in 2 modes, pointing and scanning: its batteries would point continuously at the sun as the vehicle moved 1°/day in the ecliptic longitude, and its detectors would scan in wide circles perpendicular to the plane of the ecliptic. TRW had built the spacecraft equipment module (SEM) containing all the subsystems used by all the experiments for operation and control, and a mission unique experiment module (EM) filling the requirements of each payload segment. Dr. Fred Speer, HEAO manager at Marshall Space Flight Center, said the spacecraft, rotating end over end, would survey the entire sky within its 6mo lifetime.
This launch was the first in a three mission program to study x-rays, gamma rays, and cosmic rays emitted by stellar sources, the other launches to be in 1978 and 1979. The HEAOs would carry large and heavy scientific instruments needed for observations at the high-energy and low-flux levels of these phenomena. Estimated cost of the 3 observatories was $237 million.
The original plan in 1968 had been to launch a 40ft vehicle weighing 22 0001b; budget problems had reduced the size of the undertaking. However, the x-ray detector built by NRL as 1 of 4 experiments carried by HEAO 1 was the largest instrument ever flown on an unmanned satellite, weighing almost 10001b. The NRL package, called the large area x-ray survey, was a 7-module array 20 times as large as any of its predecessors that would map the sky by recording incident x-ray fluxes and would determine the spectrum, time, and intensity variations of newfound x-ray sources. NRL's Dr. Herbert Friedman noted that known x-ray sources now numbered about 200; HEAO 1 might increase the list to several thousand. Celestial sources of x-ray emission included white dwarfs, neutron stars, and black holes, products of stellar catastrophe, as well as quasars and radio galaxies; also, a class of ministars almost too small for detection by the biggest optical telescopes might emit radiation 10 000 times as great as all the radiant energy of earth's sun.
The other experiments on HEAO 1 were a scanning-modulation collimator to make parallel observations, using instruments designed by Harvard and MIT, to pinpoint locations of sources and determine their structure; a cosmic x-ray experiment designed by NASA and CalTech, to look for diffuse x-rays or cosmic rays; and another experiment from MIT and the Univ. of Calif. San Diego, to look for hard x-rays and low energy gamma rays. NASA planned a guest observer program for this mission, participants to be selected from responses to a "Dear Colleague" letter issued by the Office of Space Sciences.
A malfunctioning rate gyro had delayed the planned June 30 launch; the Bendix-built instrument had been removed and returned to the manufacturer March 31, but further similar delays occurred [see July 26]. Early data from orbit showed spacecraft systems and experiments were operating normally. (NASA Releases 77-45, 77-56, 77-71, 77-83, 77-87 OSS rept S-832-77-01 [prelaunch] May 16/77, July 29/77; MOR S-832-77-01 [postlaunch] Aug 12/77, Apr 3/78; MSFC Releases 77-32, 77-64, 77-107, 77-142; KSC Releases 85-77, 140-77; Spacewarn SPX-284; NYT, Apr 10/77, 23; Aug 13/77, 33; NRL Release 23-8-77S)
The Shuttle orbiter Enterprise made its first free flight at Edwards Air Force Base in Calif. with a "flawless landing" on a runway in the Mojave desert 53min 51sec after taking off at 8am local time (llam EDT) and 5min 22sec after release from its 747 carrier. Astronauts Fred W. Haise, Jr., and Charles Gordon Fullerton were the Enterprise pilots; veteran test pilots Thomas C. McMurtry and Fitzhugh L. Fulton, Jr., flew the Boeing 747.
Spectators, estimated to number about 70 000, had begun arriving the previous night (Thursday, Aug. 11) to cheer the landing just after 9am local time with the desert temperature nearing 100°F. The orbiter had separated from its carrier 3min late because the heat of the air had slowed the climb. The 747 had "strained its engines" to carry the 73ton Shuttle as high as possible; it had climbed to 27 000ft (8100m) before it started downward, in order to gain speed. The 122ft-long orbiter, released at 22 100ft (6738m) altitude, had soared one way, the 747 another, to ensure separation. Pilots of the T-38 chase planes following the flight had assured the crews of the 743 and the orbiter that they were clear of each other. "Thanks for the lift," Haise told the 747 crew as the craft separated.
Haise had rehearsed the free flight the previous day in a small twin engine jet modified to behave like the Shuttle. Actual separation, which could not be rehearsed in advance, was the only way to prove that the Shuttle would lift cleanly over the tall vertical tail fin of the 747.
Separation had occurred without difficulty, however, and both pilots reported themselves delighted with the orbiter, which had handled in unpowered flight as easily as design engineers had predicted. It was "a lot like flying a Concorde," according to Haise, and Fullerton described it as a "very crisp, very stable airplane." On the orbiter's way down, Haise had pulled up in three inflight "flare" maneuvers to test its landing characteristics. One of the identical redundant computers on the orbiter had failed at separation, cutting off flight-control accelerometers, without affecting the flight.
The Enterprise landed like a glider, without engines, relying on its battery of computers and "the most advanced control system ever installed in a spacecraft." It had approached the ground at an 11° angle, more than 3 times as steep as a commercial jetliner's approach, and at a speed of 338kph (210mph) compared to a typical 747 landing speed of 170mph. The orbiter had touched down a mile in front of the aiming point, because Haise underestimated its glide capability; it had rolled another 2mi before stopping.
For this first free flight, the orbiter wore a tail cone over its three aft rockets; on the fourth flight, scheduled for Oct., NASA would remove the cone, causing the orbiter to land more steeply (as it would upon returning from space). In regular use, the Shuttle as a weight-saving measure would have no power after firing its rockets to deorbit, no airbreathing engines for maneuvering in the atmosphere; it would be slowed by air friction only and would glide down at 200mph or more to a landing. For the actual spaceflight early in 1979, the Shuttle would ride into orbit pushed by solid-fuel rocket motors on a giant external tank and by the liquid-fuel rockets on its tail.
Purpose of the free flight exercises was to verify the orbiter's subsonic airworthiness, the operation of the integrated system, and the pilotguided vs. automatic approach and landing capabilities. The ability to land at an airport instead of parachuting into the ocean gave the Shuttle the "versatility and economy required to make space operations routine in the next decade," according to the W. Star. (NASA Release 77-160; NASA Actv., Aug/77, 2; NYT, Aug 13/77, 1; W Post, Aug 13/77, Al; W Star, Aug 13/77, A-3; B Sun, Aug 12/77, 7; C Trib, Aug 13/77, 1-1; Time, Aug 22/77, 64)
MSFC announced that a young student assistant under the first NASA research grant awarded Alabama A&M Univ. 12yr ago, now a nationally known organic mass spectrometrist, had become a NASA researcher again, representing Meharry Medical College and the Natl. Inst. of Health as a summer faculty fellow. Dr. Stanley L. Evans, one of 23 researchers selected for the Aeronautics and Space Research Faculty Program sponsored by NASA and the Am. Society of Engineering Education, would study separation and preserving of cells in zero gravity. (MSFC Release 77-144)
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