NASA's mission is ``probably more difficult than that of any other organization in the world,'' says a report by the advisory committee on the future of the U.S. space program. It offered this illustration of what makes the National Aeronautics and Space Adminstration's job so tough: ``Each Voyager spacecraft has the electronic circuitry of over 2,000 color television sets, yet is required to work for 12 years while traveling from Earth to Neptune. ``The two Voyager spacecraft schedules were absolutely unforgiving, the planets in their paths aligning themselves only once every 176 years. Yet by the time Voyager 2 reached Neptune, 4.4 billion miles away and 12 years later, the spacecraft was a mere 22 miles off its charted course and only one second off its updated flyby time. ``Mechanical challenges are equally impressive. Each space shuttle contains some 300 miles of electrical wiring, over 3,000 feet of welds and over 2.5 million lines of software code. Its pumps propel 65,000 gallons (the capacity of a large swimming pool) through its engines each minute. ``The power turbine on the shuttle operates at a temperature of 1,300 degrees Fahrenheit. Just four feet away, the pump turbine operates at minus 400 degrees Fahrenheit .... ``The Hubble Space Telescope involved a total of over 40 million hours of work. To process a space shuttle for flight requires that 1.2 million separate procedures be accomplished. ``Furthermore, NASA must do all that it does in the public spotlight - which is, of course, as it should be.''
