The apparently successful test of a redesigned booster for the space shuttle has moved the United States a step closer to returning its astronauts to orbit. But concerns linger about the booster-testing program itself, and some experts want to see greater presidential leadership in charting a long-range course for the space program. Sunday's full-scale test of a development version of the solid-fuel booster represents the latest waymark in the National Aeronautics and Space Administration's (NASA) effort to get the shuttle program off the ground following the explosion of the orbiter Challenger in January 1986.
The space agency passed the first of those waymarks early last month, when workers at the Kennedy Space Center turned on the electrical power in the orbiter Discovery and began checking out its electronic gear in preparation for a June 2, 1988, launch.
In addition, NASA has given Rockwell International the go-ahead to begin work on a shuttle to replace Challenger, bringing the fleet strength back up to four orbiters. The $1.3 billion project, which will use existing structural spare parts as the basis of the new shuttle, is expected to be completed in April of 1991.
The solid-fuel booster test, conducted at Morton Thiokol's Wasatch Facility near Brigham City, Utah, was the first full-scale attempt to evaluate a number of changes made in the booster, including those made to the joints between booster sections.
Challenger's explosion was traced to a failure of seals along one of those joints to hold in searing exhaust gases. Although Sunday's ``burn'' looked good to engineers from NASA and Morton Thiokol, they say it will take about two weeks to analyze all the test data.
One more test of a development motor is scheduled, to be followed by at least three tests of qualification motors. Those motors would be identical to the ones the shuttle would use, says Myron Uman, project director for the National Research Council panel advising NASA on the redesign program. Additional tests will be conducted even after the shuttle resumes operation.
A remaining concern about booster design involves the reliability of the joints between the bottom of the booster and the nozzle, which slides into the bottom of the booster and serves as the exit channel for its exhaust gases. ``All along, the panel has been concerned that work has focused on the base-line design without adequate attention to alternatives,'' says Mr. Uman.
For its part, NASA maintains that it has to focus on modifications to the existing design because it doesn't have the manpower to pursue alternatives, even though some variations in design are already on the shelf.
``Personally, I think NASA is rushing things,'' Mr. Uman says. ``NASA people are working under enormous pressure. They're working seven days a week - they have been since the Challenger accident - because there are some very important concerns about getting the shuttle going again.''
Booster redesign was one of several recommendations made in the Rogers Commission report on the Challenger accident, submitted to President Reagan in June 1986. The recommendation dealt with three broad areas: technical changes in the orbiters and their engines; changes in the way the agency develops data on and communicates about safety issues; and changes in personnel and organization.
``NASA is doing a good job in correcting the technical deficiencies,'' says Robert Bowman, president of the Institute for Space and Security Studies in Potomac, Md.
And the management changes are ``fairly well implemented,'' says John Pike, director of space policy for the Washington-based Federation of American Scientists, adding that it will be difficult to gauge how well the changes work until they're put to the test.
But even when the shuttles thunder skyward again, the US space program is likely to be missing an element crucial to its long-term success, say US space-policy analysts - the political leadership needed to turn neatly outlined objectives into concrete, funded projects.
The latest addition to the stack of space-goal studies came last week with a report to NASA by a team headed by astronaut Sally K. Ride.
The study urges NASA not to rush headlong into a manned trip to Mars, but to procede in an orderly manner with interim projects such as studying Earth from satellites, sending unmanned probes to study the planets, and setting up a scientific and industrial base on the Moon.
``The information is all there,'' says Dr. Bowman of reports that outline goals for the US space program. ``I'm not sure we have the political leadership to make it happen.''
Space-policy analysts say that leadership has to come from the White House.
``There's no way you can generate support for these programs at the agency level,'' Mr. Pike says.
``Congress will fund a program that makes sense and that is proposed with presidential leadership,'' Bowman says.
Without that leadership, NASA will have a tough time overcoming what Mr. Chartrand calls its biggest problem - low morale, which transcends the Challenger explosion. ``Experienced people are leaving. People are complaining about science,'' he says, referring to the fact that the decade of the 1980s will pass with no new US space probes launched.
While by no means a cure-all, a successful launch of the shuttle next June would be a big help. Says one analyst, ``Until the shuttle flies safely, morale at NASA isn't going to change much.''