December 1982:space activities report

THE STS-5 MISSION

The Space Shuttle is scheduled to begin its operational phase on 11 November with the launch of Orbiter Columbia on its fifth flight. The main cargo consists of two paying passengers: the SBS and Telesat communications satellites.

Kennedy Space Center Shuttle Project Engineer Robert Sieck explained that several significant changes to the spaceship were made during the eight weeks it spent in the Orbiter Processing Facility, changing it from a development vehicle into a spacecraft designed for operational use.

“Perhaps the biggest single difference will be the added crew accommodations." said Sieck. “We have four crew members on the fifth mission, instead of only two, and we have to add seats and other provisions for them, such as communications and emergency oxygen. Besides the commander, Vance Brand, and pilot, Robert Overmyer, two mission specialists will fly: Dr. Joseph Allen and Dr. William Lenoir. They will be responsible for the deployment of the communications satellites as well as the operation of other experiments carried aboard”.

Sieck said that one seat was installed on the flight deck between and to the rear of the two pilots’ seats, with the other on the mid-deck. “They are foldable and will be tucked out of the way for the on-orbit portion of their mission.”

Because the STS-5 mission will be shorter than the previous two missions, Dieck said that one set of oxygen and hydrogen tanks which feed reactants to the electricity-producing fuel cells was removed, saving about 1,300 lb (600 kg) in weight.

“As another weight and cost savings measure, the ablative panels on the Orbiter’s elevons will eventually be totally replaced with the reusable thermal protection tiles. About 80 tiles were bonded in position there for this next mission. Replacing the ablator with tile will save about $500,000 on each flight when that job is complete."

Other than changing ablator for tile, Sieck said that much less work was needed on the Orbiter’s thermal protection system than was required following previous missions. Tiles damaged from the unexpected hail storm that pelted the Orbiter the night before the STS-4 launch in late June were repaired in place. "There were 400 tiles identified as subjects for densification. Technicians removed and densified tiles on an 'opportunity basis’, but the STS-5 mission could be flown without densification of any tiles.”

Another weight-saver was the removal of the 900 lb (400 kg) Remote Manipulator Arm. Sieck explained that development tests with the Canadian-built mechanical arm are complete, and engineers are satisfied with its performance. The arm is not needed on this particular flight. The two communication satellites will sit in their own cradle-like devices that have a spin table and spring mechanism to first rotate them to about 50 revolutions-per-minute, then "pop” them into space at about 3 feet per second (1 mps). Columbia will be some distance away from the satellite when a pre-set 45 minute timer ignites the solid propellant Payload Assist Module to push the spacecraft up to a geosynchronous altitude of about 22,300mi (36,000 km) above the Earth.

Another item removed was the 800 lb (360 kg) Induced Environmental Contamination Monitor, used extensively on flights 2, 3 and 4 to check for contaminants in and around the Orbiter’s cargo bay that might adversely affect delicate experiments. Changes were also made to the complex network of instrumentation. Some of the Development Flight Instrumentation sensors were moved to other parts of the spaceship, or made part of the Operational Instrumentation system.

“During the post-STS-5 modification period, the entire DFI package will be removed and replaced with a compact measurement unit," Sieck said. “Changes in location of these sensors will be compatible with the new measurement system. Major changes were also required for the two commercial satellites, but with the idea that those changes will be compatible with future commercial customers as well.”

Sieck said that, in order to monitor the spacecraft’s vital functions, as well as being able to send commands to the satellites and their associated handling equipment, "black boxes” were installed as part of the Operational Instrumentation system. Other “black box” changes were made to improve the reliability of the flight control system.

The number of problems arising from the STS-4 flight that engineers had to fix prior to STS-5 was dramatically lower than on any previous flight: from about 150 items after STS-1 tonly about 20 as a result of STS-4. The major hardware changes were the removal of the No. 1 fuel cell, replacement of the No. 3 Auxiliary Power Unit and its associated Water Spray Boiler, and the changing of a thruster on the Forward Reaction Control System. The fuel cell was to be returned to its manufacturer. United Technol¬ ogies, for "troubleshooting”, with the possibility of it being reinstalled if it could be repaired in time. The suspicion was that there was a temperature control problem indicated by a low exhaust outlet temperature seen during STS-4.

Columbia, delivered on July 15 to Kennedy on the back of NASA’s 747 Shuttle Carrier Aircraft, was processed in Bay 1 of the sophisticated hangar. Next door, in Bay 2 of the Orbiter Processing Facility, sits Challenger, Columbia's sister ship, also being readied for space flight. Challenger’s first mission is scheduled for this January.

Columbia was towed over to the Vehicle Assembly Building in mid-September where it was mated with the two Solid Rocket Boosters and External Tank. Various tests, including a simulated countdown with the flight crew, and a loading test of the External Tank with liquid hydrogen and oxygen were performed at the pad. The hypergolic propellants were to be loaded aboard Columbia, and the two communications satellites inserted in the cargo bay, prior to starting the countdown for an 11 November launch.

The five day mission is scheduled to end with a landing on the desert lakebed at Edwards Air Force Base in California. Columbia will then be returned to Rockwell International’s Palmdale Facility in California for modifications. Challenger will be used while Columbia is being outfitted for operational duty.

LATEST DELTA SUCCESS

The launch of the Anik-D1 communications satellite on 27 August marked the first use of the Delta 3920/Payload Assist Module combination, as well' as being the 30th consecutive successful launch of the basic vehicle. The new Delta 3920 series went into operation on 16 July with the launch of NASA’s Landsat 4 Earth resources satellite from the Western Missile and Test Range at Vandenberg Air Force Base in California.

Despite the introduction of the Space Shuttle, the number of satellites awaiting launch is greater than ever. The Anik satellite was sent aloft from the newly-refurbished Pad 17B at Canaveral, the first use of the facility for four years; NASA believes that the two Delta pads will allow them to make 18 firings a year.

The Delta was first introduced in 1960 (with the unsuccessful attempt at orbiting the first Echo balloon) to satisfy the demand for a medium-payload vehicle. It has proven itself to be the world’s most reliable expendable launch vehicle, with an over¬ all success rate of 93.4 per cent, including 94.7 per cent since July 1972 and 100 per cent since 22 October 1977.

During its more than two decades of service, Delta has kept pace with satellite customers’ demand for greater payload capacity and more sophisticated mission capabilities. Today’s most powerful model can launch 28 times as much payload into a geosynchronous transfer orbit as the first version. As the high volume of demand for Delta-class payload launches (both firm missions and Space Shuttle backup missions) developed for the 1980’s, it became clear that the vehicle had to be kept in the intentory. The Delta 3920/PAM used in the Anik-D1 launch is one of four versions in service, each a three-stage vehicle augmented by nine solid propellant strap-on boosters. As the most powerful of these, the 3920/PAM can boost payloads of up to 2800 lb (1720 kg) to Earth-synchronous orbits 22,300 mi (35,880 km) high.

The first PAM was flown in November 1980 when Delta 153 successfully launched the SBS-1 communications satellite. Seven PAMs have now lifted payloads into geosynchronous orbit from Delta 3910s.

ESA ORBITING OBSERVATORY

One of the five European proposals being put forward as the next ESA satellite project is that of Magellan, writes Andrew Thomson. The UV astronomical observatory will be in competition with the ISO (Infrared observatory), X-80 (X-ray observatory), Disco (solar astronomy) and Kepler (Mars orbiter) proposals for selection next March.

Magellan would orbit a far-ultraviolet (UV) spectrograph to survey our own and other galaxies. The spectrograph, with high resolution and sensitivity, would cover the 500-1400 7 wavelength range. Current UV missions such as the International Ultraviolet Explorer and the Space Telescope do not venture into wavelengths shorter than 1150°. Wavelengths below that are still basically unexplored except for a very few observations of very bright objects made by the "Copernicus” Orbiting Astronomical Observatory launched ten years ago.

Magellan is a revised version of the MISIC (Milieu Interstellaire et Intergalactique) instrument originally proposed by French and American groups within the framework of the Space Shuttle programme. With the shuttle delays, laboratory studies of the instrumentation were continued, indicating that a free-flying satellite was timely. The observatory is designed to cover a wide range of subjects: the composition and behaviour of interstellar matter (in our own and other galaxies); the chromospheres and coronae of stars; binary star systems, and star clusters; stellar mass loss; galactic nuclei and quasars; intergalactic matter; and planetary physics. .

Magellan can be expected to contribute significantly to our understanding of the evolution of galaxies. Matter is cycled continuously from the interstellar medium to stars, and back again via mass loss and explosions. Magellan will observe the state of this matter during most of its phases: inside the interstellar medium, in the atmospheres of stars, in stellar winds and ejecta, and even at the surface of stellar remnants such as white dwarfs and, possibly, neutron stars.

The satellite would be placed into a highly eccentric (1000X71,000 km) 24-hr orbit following launch by an Ariane 2 or 3. Total payload mass would be in the 200 kg range, the whole spacecraft weighing approximately 700 kg (fully fuelled). It would be designed for a lifetime of two years, although it could observe the full celestial sphere within six months.