Space Shuttle Atlantis, a testament to advanced engineering and manufacturing, was a complex vehicle designed for repeated journeys into Earth's orbit. Its construction involved a meticulous process spanning several years, culminating in a spacecraft that was both robust and efficient. From its initial contract award to its first flight, every stage was carefully managed to ensure the orbiter's capability to withstand the rigors of space travel. Understanding
its specifications and the maintenance it underwent provides insight into the technological prowess required for the Space Shuttle program.
From Assembly Line to Launch Pad
The journey of Atlantis began on January 29, 1979, with the contract award to Rockwell International's Space Transportation Systems Division. Structural assembly of the crew module commenced on March 30, 1980, followed by the aft-fuselage on November 23, 1981. A significant milestone occurred on June 13, 1983, when the wings, manufactured by Grumman, arrived at Palmdale, California. The final assembly phase started on December 2, 1983, and was completed by April 10, 1984. This rapid construction timeline meant Atlantis was completed in about half the time it took to build Space Shuttle Columbia.
After its completion, Atlantis rolled out from Palmdale on March 6, 1985. It then underwent overland transport from Palmdale to Edwards Air Force Base on April 3, 1985, before being delivered to the Kennedy Space Center on April 13, 1985. A crucial Flight Readiness Firing took place on September 12, 1985, ensuring all systems were operational for its maiden flight, STS-51-J, which launched on October 3, 1985. When it rolled out of the Palmdale assembly plant, Atlantis weighed 68,635 kg (151,314 lb), making it nearly 3.5 short tons (3.2 t) lighter than Columbia, a testament to continuous improvements in design and materials.
Key Specifications and Design Features
Atlantis possessed impressive dimensions and capabilities. It had a dry mass of 78,000 kg (172,000 lb). Its length measured 37.2 meters (122 ft), with a height of 17.2 meters (56 ft) and a wingspan of 23.7 meters (78 ft). These specifications allowed it to carry significant payloads and perform complex orbital maneuvers. The orbiter's structure was primarily made from aluminum alloy, though later orbiters like Atlantis incorporated graphite epoxy in some structural elements to reduce weight. The windows were constructed from aluminum silicate glass and fused silica glass, comprising an internal pressure pane, a 1.3-inch-thick (33 mm) optical pane, and an external thermal pane, tinted with the same ink used for American banknotes.
Electric power for Atlantis's subsystems was supplied by three hydrogen-oxygen fuel cells, producing 28-volt DC power, which was also converted to 115-volt 400 Hz AC three-phase electric power for specific systems. These fuel cells powered the entire Shuttle stack from T-minus 3 minutes 30 seconds through the end of the mission. The hydrogen and oxygen were stored in cryogenic tanks in the mid-fuselage, with a variable number of tank sets installed depending on mission requirements. The fuel cells could generate 21 kilowatts of continuous power, with the orbiter consuming an average of about 14 kilowatts, leaving 7 kilowatts for the payload. Additionally, these fuel cells provided potable water for the crew.
Maintenance and Modernization Through Its Lifespan
Throughout its operational history, Atlantis underwent two major overhauls known as Orbiter Maintenance Down Periods (OMDPs). The first OMDP occurred in October 1992, lasting 20 months. During this period, 165 modifications were implemented, including the installation of a drag chute, new plumbing for extended duration missions, improved nose wheel steering, over 800 new heat tiles and blankets, new insulation for the main landing gear, and structural airframe modifications. The second OMDP, from November 1997 to September 1998, involved 130 modifications. These included the integration of glass cockpit displays, replacement of TACAN navigation with GPS, and the installation of an International Space Station (ISS) airlock and docking mechanism. Weight reduction efforts were also undertaken, such as replacing Advanced Flexible Reusable Surface Insulation (AFRSI) blankets with lighter FRSI on upper surfaces and installing lightweight crew seats. The Extended Duration Orbiter (EDO) package, installed during OMDP-1, was removed to lighten Atlantis, optimizing it for its primary mission of servicing the ISS. After the Columbia accident, Atlantis received over 75 modifications, ranging from minor bolt change-outs to window replacements and fluid system updates, ensuring enhanced safety and performance for its remaining missions.
