A lack of launch opportunities could force American space scientists to look to other countries to loft their orbiters and planetary probes. In an interview, Lew Allen, director of the National Aeronautics and Space Administration's Jet Propulsion Laboratory, described the frustration that has enveloped the US space science community, which has not seen the launch of a new planetary mission in more than 10 years. When asked if there was a chance that the United States would use rockets such as Western Europe's Ariane to launch missions developed solely by the US, Dr. Allen replied, ``There could be. My own view is that technology transfer and other issues are not so great as to preclude it. If there are opportunities to do good science, and it can be done using other people's vehicles, we should not shy away from that.''
At the same time, he says, it is unacceptable for the US to continue much longer without adequate access to space using its own launch vehicles. The commercial success of rockets coming into the US stable depends on how often they're used, he explains, ``so one doesn't want to shift too many payloads off to somebody else's launch vehicle.''
Already, US scientists have collaborated with the Japanese on that country's Ginga orbiting X-ray satellite. The US is also collaborating with France to build Topex, an experiment to use radar to measure ocean currents. Scheduled for launch in December 1991, Topex will ride into orbit atop an Ariane rocket.
``And, of course, that's a comforting thought right now,'' Allen says with a chuckle. He expresses general satisfaction with the latest revisions in the shuttle payload schedule, made before last month's unexpected failure of a shuttle solid rocket motor. A spokesman at NASA's Marshall Space Flight Center in Huntsville, Ala., says that the revised manifest includes about four months' worth of wiggle room to allow for unexpected delays. If NASA has accurately estimated the delay resulting from the booster failure, that manifest should stand.
In addition, NASA administrator James Fletcher has said that four major missions - Magellan to Venus; Galileo to Jupiter; the US-European project Ulysses, which will study the polar regions of the sun; and the US Mars Observer - have the space agency's highest priority after national-security payloads.
The decade-long dearth of US launches has been hard on the space science community. It has also taken its toll on the Jet Propulsion Laboratory.
``JPL is a bit of a graying organization,'' Allen says, pointing out that some going into retirement were responsible for JPL's past successes. ``With the 10-year period in which no spacecraft have been launched, I'm concerned that the skills are not honed'' sufficiently to ensure that future missions are as successful.
This institutional concern, plus input from the space science community at large, has led to discussions of less expensive missions that take advantage of microminiature technologies ``to permit important scientific experiments to be done on very small vehicles,'' Allen says.
Two concepts have filtered to the top of the pile. One is an unmanned orbiter that would circle the moon's poles in search of water.
Some scientists hold that there are permanently shadowed areas in these polar regions that could hold substantial amounts of water in the form of ice. Cost estimates for the trip range from $30 million to $40 million.
In addition, Allen suggests the possibility of a mission to support the space station project by taking debris measurements in space. The results would help station designers develop adequate shielding for the manned facility.
In taking a broad look at the future of the US space program, Allen calls for a more balanced view of NASA's role in space. ``I believe that the other activities of NASA should not be regarded as secondary offshoots'' of the manned spaceflight program, he says. ``I'm thinking particularly of science and technology.''
``NASA should consider its mission to accomplish space science as a mission to be accomplished by the most effective means that it can, whether or not that involves a manned spacecraft. And in most cases it won't. The budgets and allocations of resources to that should stand on their own, in contrast to being a percentage of the manned flight endeavor.
``Similarly,'' he continues, ``the technology programs of NASA, which have over recent years been limited to the development of technologies that are most important for the manned missions, should be expanded to have a characteristic closer to the aeronautics activities of NASA,'' in which NASA research supports that of commercial and military interests ``and not just some NASA institutional interest.''