THE DECISION TO BUILD another space shuttle, and thereby have a shuttle based on the West Coast, is a sound and well-reasoned one.

In an era when instruments of global destruction travel at orbital altitudes, it would be naive to believe the United States could have afforded to limp along with its manned space fleet crippled. Even with heavy reliance on expendable boosters, the nation's space program almost certainly would have fallen behind without the replacement space shuttle.Without the additional manned spaceship, many of the scientific and technological projects that cannot be done with unmanned boosters would have been shelved. Indeed, many of the advances that have resulted from research aboard the shuttle might have languished for lack of follow-up.

What's more, a smaller shuttle fleet probably would have precluded any use of the new spaceport at Vandenberg Air Force Base northwest of Santa Barbara. That launch site is crucial to exploration of space, because satellites and men can be launched safely from there into polar orbits. A polar launch from Kennedy Space Center would put the cities of southern Florida in severe danger in the event of an accident.

Only on such polar flights can astronauts, or automated cameras, survey the entire surface of the earth, which turns under them as they make repeated passes over the north and south poles.

What's more, the prospect of a complete ban on launch of commercial satellites from the shuttle would have turned a whole generation of satellites that exist or are under construction into junk. As satellite builders learned when they switched from expendable rockets to the shuttle, it's very difficult to switch a satellite designed for one type of launch onto a different type of vehicle without greatly increasing the chances of failure. Owners of the $40 million to $60 million Palapa B-2 and the Westar IV satellites, which had to be rescued and brought back to earth, can testify as to why a failure on orbit is not a good idea.

President Reagan's decision to both order a new shuttle, and have most commercial satellites launched on expendable boosters, recognizes this. It also recognizes that orbital economics dictate that some cargo be delivered to space without the additional weight and risks associated with having a crew aboard. Just as maritime companies have reduced the size of their crews, the nation's space program has had to acknowledge that some cargoes cannot bear the added expense of lugging along a crew and its life-support systems.

In the ocean shipping business, no one would suggest seriously that breakbulk ships be banned from the oceans because containerized ships have proven highly efficient. Quite the contrary, breakbulk ships play a vital role in complementing and supporting containerships.

In the same respect, it makes no sense to ban low-cost, throwaway boosters. They are needed when what's required is simple delivery to orbit. Their availability will allow the United States to use the shuttles for things that cannot be done entirely with automated systems or remote control. For example, it might be most practical to boost material for the new space station into orbit on unmanned boosters, then send men up in the shuttle to sort out the inevitable glitches that pop up in construction.

Some of the latest successful flights of the shuttle showed exactly how important this can be. For example, efforts to recover and repair satellites each ran into unexpected problems. But the humans aboard were able to improvise, manhandle the satellites and complete their assignments.

The decision to go to a mixed space fleet, with both boosters and a replacement shuttle, also makes wise use of the money invested in the West Coast's new spaceport. Permanently mothballing the completed launch site at Vandenberg would have been akin to building an entirely new seaport and then not using it for lack of ships. Abandoning the new manned space center would have been nearly as much of a wrong turn as when an entire squadron of Navy ships ran aground in the fog a stone's throw from the launch site back in the 1920s.

Nor is it possible to ignore the defense implications of building an additional shuttle. The Air Force this year began a major undertaking aimed at developing a trans-atmospheric vehicle - a craft that would take off like an airplane, reach hypersonic speeds, then launch a small rocket plane into space. But construction of such an orbit-on-demand craft is still many years away. In the meantime, there must be adequate shuttle capacity to support military projects and carry out polar-orbiting scientific exploration.

With 30 of 44 scheduled satellites due to move onto private boosters, companies such as Martin Marietta, General Dynamics, Hughes Aircraft, Boeing Aerospace, Transpace Carriers and Space Services can expect to share in a business estimated to require $6 billion in boosters in the next half dozen years.

Len Thorell of Todd Shipyards Corp. used to tell his men that they have nothing to fear from robot welders in the shipyard, because they do nothing but free humans from mundane, repetitive tasks to concentrate on the important work. In the same way, greater use of unmanned boosters and automatic systems will free shuttle astronauts to concentrate on the important work in space.

For the full story: Log In, Register for Free or Subscribe