National Aeronautics and Space Administration (NASA)
National Aeronautics and Space Administration (NASA)
The National Aeronautics and Space Administration (NASA) was formed in 1958 from the National Advisory Committee on Aeronautics (NACA) and other agencies in the military and government that might benefit from a centralization of efforts in air and space research. Within a decade, NASA had three piloted and several unpiloted space projects either complete or in the works. In the next few years, NASA introduced digital computers to aeronautics.
During its first fifteen years, NASA experienced its greatest period of influence on computing, both in hardware and software. Since the mid-1970s, NASA has become more of a user than an originator of computing technology, though several research programs still exist. NASA's need for cost-effective and innovative solutions to problems of navigation, safety, and communication has significantly influenced the development of computer technology, particularly in the application of embedded real time systems, redundancy, networks, large systems, and new computing hardware technology.
Embedded Real Time Systems
Software engineer David Parnas once said that "all systems are real time systems, it is just that some are faster than others." A real time system has to achieve its results in a time indistinguishable from when they are needed. Air traffic control, anti-lock brakes, and microwave ovens are all real time systems according to that definition. When NASA was formed, the technology of the day made real time systems considerably rare. NASA soon determined that one of the great difficulties of travel to the Moon is navigation, and it decided to design the Apollo spacecraft with a real time system for flight control. This is also known as an embedded system because the computer and its software are an integral part of the entire subsystem, like the computer in an automobile.
The first piloted NASA spacecraft was Freedom 7 with Project Mercury, which had no computer-controlled guidance on board. The second group of spacecraft was within Project Gemini. NASA chose Gemini to introduce and test the use of on board computers to provide flight control and navigation. The Gemini and subsequent Project Apollo computers had to be relatively small, about 25 kilograms (55 pounds). They had to operate in real time, since they were used in flight control. Both were a significant change from NASA's room-sized ground-based computers in size and speed, yet both were much less capable than present-day desktop computers.
For example, although personal computers now have millions of words in memory, the Apollo computer had only 36,000. And although the ubiquitous microprocessors in microwave ovens and automobiles have small memories, they are much faster than the 6,000 operations a second that the Gemini computer could manage. A special case of an embedded real time system is airplane flight control. NASA put a surplus Apollo digital computer into a Navy F-8 and flew it in 1972. Now, almost all military and commercial aircraft use such "fly-by-wire" systems. It was NASA's requirement for embedded real time systems on both piloted and unpiloted spacecraft that led to the creation of many of the commercial and consumer systems we take for granted today.
Real time embedded systems in life-critical applications, such as flight control and life support, must not fail. Also, long duration unpiloted missions cannot repair a failure. Since NASA frequently conducts both types of flights, reliability has been a continuing concern to the agency. NASA most often ensures reliability through redundancy and backup, as opposed to ground-based systems that can be fixed readily. Perhaps the finest example of a redundant system is the data processing system on the space shuttle orbiter that uses four identical computers in a redundant set and a fifth identical computer running backup software. This concept has been adapted in business and industry to ensure safety and stability in computer-based operations.
Computer users today take high speed Internet access for granted, and rue the slowness of a 56K baud modem. "Baud" means "bits per second," a measure of the volume of communication. However, NASA ran the Mercury man-in-space program (1959–1963) with only a 1K baud connection! NASA had radar systems at Cape Canaveral and in Bermuda to track the ascent of Mercury launches. The radar information was received at a computer site near the White House on Pennsylvania Avenue in Washington, D.C., at 1,000 bits per second. The computer determined the flight path of the spacecraft and generated displays back in Florida so that the engineers could track the rocket's progress. This is one of the first uses of remote computing, and NASA built many more networks to support all kinds of spacecraft data and communications. Included in these are the complex networks and processors on board each piloted and unpiloted spacecraft.
When NASA was formed, the average computer system filled a room, but was still relatively small in terms of memory that could be accessed quickly. Many computers had a read/write memory of only 2,000 to 16,000 words, compared to machines in the early twenty-first century that have millions of words in storage. Magnetic tapes stored large groups of data. Apollo and other projects needed fast memories, so the IBM Corporation and other NASA suppliers experimented with large one million word memories and groups of processors. NASA has always shown an interest in big, fast machines, and has sponsored research into parallel processing , which is now commonplace in the world of information processing and analysis.
New Hardware Technology
Initially, programs like Apollo took a conservative approach to purchasing computer hardware. Piloted space flight programs were risky enough without pushing the leading edge. However, in the case of the Apollo flight computer, the gains from using relatively untried technology outweighed the risks. Also, by the time the actual Moon flights took place, several years had passed, during which newer technology was able to amass a reliability history. NASA approved the use of integrated circuits in the Apollo computer design. For a short time in the early 1960s, NASA and the U.S. Air Force (for the Minuteman missile) exhausted the entire production of integrated circuits in the United States.
In unpiloted space probes, NASA could take even more chances. Therefore, the first projects to use CMOS (Complementary Metal Oxide Semiconductor) integrated circuit technology were the Voyager probes to the outer planets. Such low-power chips have found their way onto the upgrades of the space shuttle.
Since the 1960s, NASA's need for computer technology has contributed to the development of consumer and business applications of computer knowledge. The real impact of NASA on the computing industry is that it has constantly challenged its contractors to find new solutions to exotic problems, through a blend of trusted technology and cutting-edge computer science. Many parts of those solutions are passed on to consumers in the form of new uses for computers and greater reliability in computer systems. Innovations designed to help protect the lives of NASA astronauts have become part of everyday life, from time-keeping and food preparation, to computerized automobile navigational systems and airplane flight safety.
see also Apple Computer Inc.; Bell Labs; Ibm Corporation; Intel Corporation; Microsoft Corporation; Xerox Corporation.
James E. Tomayko
Tomayko, James E. "Achieving Reliability: The Evolution of Redundancy in American Manned Spacecraft Computers." The Journal of the British Interplanetary Society 38, no. 12 (1985): 545–553.
——. Computers in Space Flight: The NASA Experience. New York, NY: Marcel Dekker, Inc., 1987. Also published as NASA Contractor Report 182505, March, 1988, reprinted on the NASA web site. <http://www.hq.nasa.gov/office/pao/History/computers/Compspace.html>
——. Computers in Space: Journeys with NASA. Indianapolis, IN: Alpha Books, 1994.
——. "The Fly-by-Wire Revolution in Flight Control." American Heritage of Invention and Technology, Winter (1992): 19–24.
——. History of NASA's Pioneering Digital Fly-by-Wire Project. NASA SP–4224, 2000.
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