Sky & Telescope June 1987 [antikvár]

focal pointIs the U. S. Abandoning the Solar System?WE certainly abandoned the Moon in 1972, at the end of the Apollo program. Now NASA estimates that to return would require 10 years and cost more than Apollo did. Some people fear that a similar retreat is in store for our explorations of the planets.By any reckoning the golden age of planetary exploration is behind us, its momentum lost in the slashed NASA budgets of the Vietnam-Watergate-Reaganomics era. Between 1962, when the first Mariner space probe was launched to Venus, and 1978, when two Pioneer Venus craft left the Earth, the United States launched 27 successful unmanned missions to the Moon and planets. But it will be 1989 at the earliest before another U. S. craft leaves on a voyage of exploration.Three planetary missions Magellan to Venus, Galileo to Jupiter, and Mars Observer await launch, but 1 'A years after the Challenger accident there is still no firm plan to deal with them. Meanwhile the spacecraft themselves are aging, and tens of miUions of dollars are being spent each year on mission redesign and parts replacement. The sad fact is that despite a total planetary budget of more than $300 million per year, the missions are not being launched and new data are not being obtained.To be sure, we are still reaping the rewards of Voyagers 1 and 2, but those probes represent early 1970's technology. Just think how consumer products have changed over the last 15 years and you can imagine how much better we can build spacecraft today! And there is no shortage of exciting planetary missions to be flown. The solar system is waiting for us to probe the atmospheres of Jupiter and Saturn, to land on the surface of Titan, to skim across Saturn's rings, to land on a comet and return a sample of its ancient pristine material, and to resume the exploration of Mars.All this is easily within our capability. It would have been affordable, too, had spending for planetary exploration continued at the level of the early 1970's. Then the planetary program amounted to almost 10 percent of NASA's research and development budget; today it is less than 3 percent.Actually, NASA has a very specific plan, prepared at the agency's own re-quest, to revitalize its planetary program. In 1980 NASA established the Solar System Exploration Committee (SSEC) to formulate guidelines to rebuild the planetary program in a scientifically exciting but cost-effective manner. This committee has just completed its final report. First outlined in 1983, it provides a blueprint for recovery but time is running out.The SSEC proposal has three main parts. The first objective, clearly, is to launch Magellan, Mars Observer, and Galileo. Until they are on their way, these missions remain an unproductive drain on our resources. Although designed for the Space Shuttle, these and other planetarymissions can all be launched just as easily, and at lower cost, by using expendable launch vehicles (ELV's). Sadly, in the year and a half since Challenger not one ELV has been ordered by NASA, which has been too preoccupied by internal problems and the restoration of shuttle flights to deal with this critical issue.The second part of the SSEC plan calls for the initiation of new planetary missions based on a generation of more capable, less expensive spacecraft called Mariner Mark II. These have been under development for five years at the Jet Propulsion Laboratory and are required if the U. S. is to reestablish its leadership in planetary exploration. Specifically, theSSEC timetable suggests new start-up funding in FY88 for a Mariner flight to Comet Tempel 2. This Comet Rendezvous Asteroid Flyby (CRAF) mission should be launched in 1992 or 1993, to be followed in 1995 by a second Mariner called Cas-sini, a joint mission to Saturn and Titan involving both NASA and the European Space Agency. But without the new Mariners and ELV's, the U. S. will not be able to fly beyond the inner solar system.The third and most ambitious element of the SSEC plan looks forward to the development in the 1990*s of new technologies for planetary exploration, with a focus on Mars. The objectives of this program are to land robot rovers on the planet's surface and to collect samples for return to Earth. Such a program could be carried out by the U. S. acting alone. But many of us prefer to explore Mars in concert with other spacefaring nations, particularly the Soviet Union, which recently redirected its own planetary program away from Venus and toward Mars.All this sounds great, but can we ever get there from our present state of weakness? The answer is yes if we act now, but the longer we wait the more difficult and expensive the task will be. NASA says it supports the SSEC plan, yet its budget request for FY88 defers the launch of Mars Observer from 1990 to 1992 and contains no new-start funding for the Tempel 2 mission. In fact, the planetary budget request is down $50 million from FY87, at a time when almost all other programs in NASA are growing.The present course could lead to the early extinction of the planetary program. Are we really prepared to give up this field of activity in which the U. S. has led the world for the past quarter century? If we are serious about the planets, we should demand that NASA and Congress take positive steps now. Mars Observer should be launched in 1990, CRAF should be started, and ELV's should be procured. It's time to stop studying the problem and start solving it!DAVID MORRISONMorrison slitdies [he planets at the University of Hawaii and chairs NASA's Solar System Exploration Committee.Focal Point invites contributions from read-ers who wish 10 comment on contemporaryissues in astronomy and space science.