Mar 8 1985
From The Space Library
NASA announced that, following launch of Atlas/Centaur 62 carrying the seventh INTELSAT V payload, a significant leak occurred in the Centaur liquid oxygen (L02) tank during Atlas and Centaur separation, resulting in loss of LO, and precipitation of a series of anomalous events that compromised vehicle performance and caused loss of the mission.
Centaur main engine start and steady-state operation began for the first burn sequence; however, the engines burned fuel rich as a result of an attempted correction of the LO, loss. Also, Centaur's first main engine cutoff had occurred approximately 11 seconds early, as a result of LO, mass loss (approximately 1483 lb.) through the tank opening. After first main engine cutoff, the leading LO, ullage gasses (HE and GO2) created a disturbing force on the vehicle, causing it to tumble out of control during the ensuing coast period.
During the coast period, the LO, tank pressure vented down to less than the hydrogen tank pressure at 1040 seconds, causing reversal and rupture of the intermediate bulkhead so that the two tank pressures were essentially the same throughout the remainder of the flight.
Although 2nd Centaur engine start was achieved, the engines shut down after less than seven seconds of operation because of inadequate tank pressurization and subsequent engine cavitation. This made it impossible to achieve proper orbit, and NASA terminated the mission.
Following the failure, NASA Headquarters initiated a Flight Review Board composed of representatives from the NASA centers, U.S. Air Force, and INTELSAT. During the investigation, NASA obtained special assistance from Physics International for analytical shock analysis of various blast-shield and tank-pressure configurations, General Dynamics/Ft. Worth Division for shaped charge firing tests and consultations, and Pratt & Whitney Aircraft for special engine testing to resolve 102 back flow anomaly and special postflight reconstructions.
The investigation teams' findings indicated that the most probable cause of the failure was due to shock induced loads on the 102 tank at high tank pressures causing tank failure. Corrective actions taken to clear AC-63 for flight would include reduced tank pressures to prior levels, increase in the interstage adaptor to blast-shield gap, and a check for ambient flight pressure and leaks on each tank. (NASA MOR M-491-203-84-07 [postlaunch] Mar 8/85)
An accident at Kennedy Space Center (KSC) today damaged the Space Shuttle orbiter Discovery and injured a technician, forcing delay in the orbiter's next flight originally scheduled for March 29, the Washington Post reported. The accident occurred about 8 a.m. when the bucket of a "cherry picker" crane hovering over Discovery fell, hitting a Lockheed technician who was on a work platform and then striking Discovery, which was horizontal on the floor of the orbital processing facility.
The 2,500-lb. bucket broke the technician's leg and injured his shoulder, then fell onto the closed left-hand cargo bay door, which was so thin and made of such light-weight material that it could not be opened on earth without elaborate supports to keep it in a fixed position. The bucket made two holes about three feet apart in the heat protection tiles insulating the door and damaged the door's structure.
A NASA spokesman said an investigating board would determine the cause of the accident, extent of the damage, and impact on the flight schedule. Officials speculated that NASA would have to replace the 2,400-lb. door, which would require shipment of a new door from the manufacturer and as many as three or four days of work to complete installation. (W Post, Mar 9/ 85, A2)
NASA announced that astronomers at the Jet Propulsion Laboratory (JPL) and the Universities of Hawaii, Arizona, and Texas were observing Pluto and its only known satellite, Charon, as the two alternately moved in front of one another in a series of eclipses that occurred every 124 years or twice in each orbit of the sun. Each time Charon passed between Pluto and earth, a portion of Pluto's surface was blocked from view, resulting in a dimming of the combined light from both bodies. When Charon moved behind Pluto, their roles reversed. Measurements of the times, durations, and changes in brightness of the events would allow astronomers to calculate the masses, diameters, and densities of Pluto and Charon, permitting development of models of the two bodies' composition.
Current estimates of Pluto's density had an uncertainty of 50%, not accurate enough to derive information on its composition. However, researchers thought Pluto's density was about that of water, making it the lowest-density planet known that had a solid surface.
The new measurements indicated that the combined brightness of Pluto and Charon diminished by 4% during the eclipses, a dimming that lasted about two hours and was superimposed on a 30% brightness change that occurred over a 6.4-day period. The longer change in brightness happened because one hemisphere of Pluto was 30% brighter than the other.
Very little was known about Pluto and even less about Charon, including when or even if the five-year-long series of eclipses would begin. In order not to miss any of the earliest events, the astronomers had established an observing network at McDonald Observatory in Texas, the University of Arizona observatories, Palomar Observatory in California, and Mauna Kea Observatory in Hawaii. Dr. Edward Tedesco of JPL had been the first to see and measure an eclipse of Pluto by Charon January 16 from Palomar; Richard Binzel observed another eclipse February 17 from the McDonald Observatory; and Dr. D. J. Tholen observed a third eclipse February 20 from the Mauna Kea Observatory. Pluto and Charon's great distance from earth and relatively small sizes made them the solar system's most difficult objects to observe. (NASA Release 85-36)
Galileo project team members would soon complete the two month-long environmental test, phase 2, of the spacecraft, during which they put Galileo in a 25-ft. space simulator, an evacuated chamber cooled to -250 to 270° F, in order to observe how Galileo functioned in a space-like environment, the JPL Universe reported. Engineers also exposed the spacecraft to an array of high-intensity quartz lamps, which simulated the solar effects Galileo would experience in space.
Jet Propulsion Laboratory (JPL) personnel would move Galileo in about two weeks to the spacecraft assembly facility for the system test, phase 3. Following spacecraft disassembly, researchers would simulate different operational phases of the mission for spacecraft testing.
Galileo was composed of a planetary orbiter and an atmospheric entry probe for investigations of the planet Jupiter's magnetosphere's chemical composition and its physical state of structure and physical dynamics. (JPL Universe, Mar 8/85, 1)
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