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| Orbiter Upgrades |
| The 21st Century Space Shuttle: New Improvements The space shuttle has undergone significant changes. From the inside out, thousands of advances in technology and enhanced designs have been incorporated into the shuttle since it was first launched. The result is a safer, more powerful and more efficient spacecraft. When the shuttle Atlantis launches on STS-101, it will be the most up-to-date space shuttle ever. From a new "glass cockpit" to main engines estimated to be three times safer, Atlantis is a far different vehicle from the one that first flew in 1985. This year also will see the 100th space shuttle launch in history, a milestone for a spacecraft that has taken over 600 passengers and three million pounds of cargo to orbit. The shuttle fleet has spent almost two and a half years in space. But even the most-traveled shuttles remain young in the lifespan for which they were built. NASA is preparing for the possibility of flying the space shuttle for at least another decade, and future improvements are geared toward a goal of doubling shuttle safety by the year 2005. The New "Glass Cockpit"  For the first time, on mission STS-101, 11 new full-color, flat-panel display screens in Atlantis's cockpit will replace 32 gauges and electromechanical displays and four cathode-ray tube displays. This new "glass cockpit," technically labeled the Multifunction Electronic Display Subsystem (MEDS), is 75 pounds lighter and uses less power than before; and its color displays facilitate pilot recognition of key functions. The new cockpit will be installed in all shuttles by 2002, setting the stage for the next cockpit improvement planned for 2005: a "smart cockpit" that reduces pilot workload during critical periods. On STS-101, Atlantis will fly with more than 100 new modifications incorporated during a 10-month period at Boeing's Palmdale, Calif., facility in 1998. The airlock was relocated to the payload bay to prepare for International Space Station assembly flights; the communications system was updated; several weight reduction measures were installed; enhancements were made to add protection to the cooling system; and the crew cabin floor was strengthened. The shuttle Columbia is at the Palmdale factory this year receiving many of the same upgrades, including installation of the new "glass cockpit." Future Shuttle Upgrades: Cutting Risk in Half by 2005 Enhancements now under development could double the shuttle's safety by 2005. New sensors and computer power in the main engines will "see" trouble coming a split second before it can do harm, allowing a safe engine shutdown. A new engine nozzle will eliminate the need for hundreds of welds and potential leaks. Electric generators for the shuttle's hydraulics will replace the highly volatile rocket fuel that now powers the system. And a next-generation "smart cockpit" will reduce the pilot's workload in an emergency, allowing the crew to better focus on critical tasks. Other improvements will make steering systems for the solid rocket boosters more reliable, make the manufacturing of solid propellant safer and increase the strength of external fuel tank welds. "Smart Cockpit"--The new "glass cockpit" that will be initiated when Atlantis launches on STS-101 is the precursor of the "smart cockpit" planned for 2005. The enhanced displays of the "smart cockpit" will not fly the shuttle, but they will do much of the deductive reasoning required for a pilot to respond to a problem. By simplifying the pilot's job, this "smart cockpit" will allow astronauts to better focus on critical tasks in an emergency. Better Main Engines--The space shuttle's main engines operate at greater extremes of temperature and pressure than any other machine. Since 1981, three overhauls of the original design have more than tripled estimates of their safety. Now, a fourth major overhaul will make them even safer by 2005. Planned improvements include a high-tech optical and vibration sensor system and computing power in the engines that detects trouble in advance. This advanced health monitoring system has sensors that will detect and track an almost microscopic flaw in an engine's performance in a split second, allowing the engine to be safely shut down before the situation can grow out of control. Also, the engine's main combustion chamber will be enlarged to reduce the pressures on internal components without reducing the thrust; and a new, simplified engine nozzle design will eliminate hundreds of welds--over 500 feet of them--and potential leaks. Safer Hydraulic Power--Aside from the main engines and solid rocket boosters, the single highest risk shuttle subsystems are the auxiliary power units, generators that power the hydraulic systems. Today, these generators use a highly volatile and toxic rocket fuel. But recent advances in battery and electrical power technology--much of which was developed by the automotive industry--will replace that system by 2005, eliminating many hazards not only in flight but also on the ground. Electric motors, powered by a bank of lightweight batteries, will be developed to power the shuttle's hydraulic system, providing greater reliability for astronauts in flight and a safer workplace for ground crews. Solid Rocket Boosters and External Tank Upgrades--Future improvements for the solid rocket boosters include a redesign of several valves, filters and seals in the steering system to enhance their reliability as well as studies of the potential for an electrical system to power the booster hydraulics. In addition, changes in the solid rocket propellant manufacturing process will make the workplace safer for shuttle technicians. For the external tank, a new friction-stir welding technique will produce stronger and more durable welds throughout the structure. Major Space Shuttle Improvements: A Brief History April 1983, STS-6: A Lighter Fuel Tank--A redesigned lightweight external tank, 10,000 pounds lighter than the original design, flew on STS-6 in 1983, increasing the shuttle's cargo capacity by the same amount. In 1998, a super-lightweight external tank flew on STS-91, further reducing the tank's weight by 7,500 pounds and again increasing the shuttle's cargo capacity by the same amount. The super- lightweight tank is made of a Lockheed Martin-developed aluminum-lithium alloy that is not only lighter but also 30 percent stronger than the previous tank design. September 1988, STS-26: Return to Flight--When Discovery returned the shuttle fleet to space following the Challenger accident, more than 200 safety improvements and modifications had been made. They included a major redesign of the solid rockets boosters, the addition of a crew escape and bailout system, stronger landing gear, more powerful flight control computers, updated inertial navigation equipment and several updated avionics units. May 1992, STS-49: Endeavour's Maiden Voyage--Endeavour's first flight in 1992 was the debut of many shuttle improvements, including a drag chute to assist braking during landing, improved nosewheel steering, lighter and more reliable hydraulic power units, and updates to a variety of avionics equipment. June 1992, STS-50: Extended-Duration Flights--Columbia was the first shuttle to be modified for allow long-duration flights and flew the first such mission in 1992. The modifications included an improved toilet, a regenerative system to remove carbon dioxide from the air, connections for a pallet of additional hydrogen and oxygen tanks to be mounted in the cargo bay, and extra stowage room in the crew cabin. June 1995, STS-71: International Space Station Assembly--The first shuttle/Mir docking mission featured new shuttle changes that allowed it to dock with the Russian space station and prepare for assembly of the International Space Station. For the shuttle to dock with Mir and ISS, the airlock had to be moved from inside the cabin to the cargo bay on all orbiters except Columbia. Weight was also reduced through lightweight lockers, seats and other cabin equipment. Those changes, coupled with the super-lightweight external tank and performance improvements, increased the shuttle's cargo capacity by 16,000 pounds since 1992. July 1995, STS-70: Space Shuttle Main Engines--Three major redesigns have more than tripled estimates of shuttle main engine safety. The first redesign (called the Block I engine), first flown in 1995, included changes to strengthen the oxygen turbopump and engine powerhead. The second overhaul, called the Block IIA engine, included a larger throat in main combustion chamber and first flew on STS-89 in January 1998. The third redesign, called the Block II engine, includes a stronger fuel turbopump and will fly for the first time in 2000. A fourth major overhaul is now planned to fly by 2005. Called the Block III engine, it will include further improvement of the combustion chamber and a simplified nozzle design. Today's Space Shuttle--Since 1992, not only has the cargo capacity of the shuttle increased by 8 tons, the annual cost of operating the shuttle has decreased by 40 percent. Improvements in the main engines and other systems have reduced the estimated risks during launch by over 80 percent. And the number of all actual problems experienced by the shuttle in flight has decreased by 70 percent. Although they have flown for almost 20 years, the space shuttle orbiters have used only about a quarter of the lifetime for which they was designed. Discovery, which has flown the most missions, has completed 27 trips to space out of the 100 flights that all the shuttles were originally designed to complete. |
