Walt Disney's Dumbo the Flying Elephant is an appropriate image for the space shuttle. Both are elephantine and, so far at least, only imaginary flying objects.

Dumbo amused the public. The shuttle is abusing the taxpayer. It is now over two years behind schedule and many hundreds of millions of dollars over budget. Despite the hoopla about paying passengers and commercial payloads, income from shuttle service will never cover costs. The American desire to put people in space has prevented open, critical examination of NASA's decisions, especially by the scientific community. The shuttle may not fly at all.

Inflation and budget-cutting demand that we acknowledge the shuttle's inefficiencies and risks. It would be prudent to postpone costly shuttle flights until an improved second-generation design can be implemented in the 1990s. In fiscal 1981 alone, we could save several billion dollars and perhaps the lives of astronauts.

The shuttle program was launched in 1972 and funded as a civilian venture. NASA convinced Congress that during the 1980s the shuttle, with its reusable orbiter, would save $5.2 billion compared with the use of conventional expendable launch vehicles. By the time the shuttle makes its first flight, the program's cost overrun could equal much of the hoped-for savings. Space research and unique opportunities to manufacture materials in near-zero gravity notwithstanding, the slowly emerging truth is that the Department of Defense will be the major shuttle user. Should military needs pressure NASA and Congress into maintaining the existing shuttle program?

What merits evaluation and examination now is the option of shortening the present shuttle program, learning as much as possible from limited suborbital flights, without high-temperature reentry, and moving on to the second-generation design. Even without shuttle flights, NASA has learned that the present design is risky, will not result in substantial cost savings and will not allow many misions to be flown. It would be courageous to accept the fact that pushing the limits of technology with minimal funding has become too costly and risky to complete as planned.

The unprecedented risk for NASA of outright failure, possibly on the first flight, results from the shuttle's unique ceramic tile system -- a system never used before. The large sums of money already spent are no excuse for continuing with what may be a deeply flawed design. The crucial decision to select aluminum covered with cermaic tiles rather than titanium as the main structural material for the shuttle may have doomed the program from the very beginning.

Each tile is specially made for a particular location on the orbiter surface. These fragile, custom-made tiles are like hand-carved glass sculptures. Moreover, each tile must be glued to the orbiter's surface by hand. The tiles are needed to protect the aluminum from the high temperatures of reentry. Thus far, the tile system has seen failures, delays and cost overruns. Tile failure on takeoff or in space would subject the shuttle to metal weakening, burning or melting during reentry. The tiles might have to be repaired in space before a return could be risked. Could such a repair mission take place? Titanium would have required a much less novel, accidentprone and risky thermal protection system.

Moreover, the figures NASA gave to Congress to justify the choice of aluminum showed it as a cost-saver. But when the total program costs are properly considered, it turns out that aluminum, with its greater weight, is costing about $700 million more than titanium. The present shuttle orbiter is 8,000 pounds overweight, resulting in the loss of 15,000 pounds of lifting capacity. This will rule out some scientific and military missions.

Yet risk to life and economic losses are not the only consequences of the aluminum design. NASA chose not to capitalize on the very large titanium R&D effort that the Department of Defense has sponsored for many years. This decision, coupled with the cancellation of both the SST and the B1 bomer, which were to use considerable titanium, left little to spur private companies to maintain and develop advanced titanium technology and manufacturing capbility. The taxpayers paid for titanium development and then paid again for not using that work. The country now has not only an aluminum Dumbo, but also an inadequate titanium capability.

Never mind the attempt to convince the American public that Captain Kirk of the Enterprise is in command of a sound NASA spaceship and that the nation's need and desire for a space program leave no room for criticism. A shuttle without tiles and using titanium as well as recently developed composite materials could be designed for larger and heavier cargoes with risks to human life on a par with past programs. With a new design, the shuttle could be made totally reusable and construction costs reduced substantially.

NASA was lucky with Skylab. For the astronauts' sake, I hope NASA is as lucky with the shuttle; and for the nation's sake, I hope the shuttle program will br redirected. There are sound reasons for maintaining a space program. But a spectacular accident could be the program's death blow. NASA should redesign and postpone rather than let space suck more public money into fewer flights with more risks than benefits.