SCIENCE SPACE TECHNOLOGY : Scientists Say Smaller Satellites Mean Bigger Payback
It may be that the best way to maintain a big space program is to think small. At least that is the opinion of scientists and engineers who believe that the future of spacecraft is in smaller satellites.
They say the National Aeronautics and Space Administration is making a colossal mistake by insisting that each generation of spacecraft be bigger and more complex than those that preceded it. NASA’s strategy is to put lots of instruments on each spacecraft so that a single propulsion and communications system can serve the needs of many scientific disciplines.
Because it is hard to get congressional approval for space projects, “the tendency has been to stuff everything on one spacecraft because we’re never sure we will get another one,” Paul Coleman, director of UCLA’s Institute of Geophysics and Planetary Physics and an adviser to NASA, told several hundred scientists and engineers who met at Utah State University recently for the fifth annual Conference on Small Satellites.
Like Coleman, most of those attending the conference believe that NASA’s approach invites disaster. If a large spacecraft fails, all is lost. It would be better, they argue, to build many smaller spacecraft, each designed to meet a specific goal. Then, if any craft fails, only that part of the program would need to be replaced.
As an example of the risk in placing too much faith in a single spacecraft, the “small satellite” proponents point to Galileo, now heading toward Jupiter with an antenna that failed to open. If the antenna cannot be fixed before Galileo reaches Jupiter in 1995, virtually the entire mission will be lost because of a single failure.
The scientists who met here are more concerned about satellites that orbit the Earth than planetary probes. They are struggling to persuade NASA to use smaller satellites, but the space agency is resisting because it costs more to launch and operate a lot of smaller “birds” than a single huge satellite.
But there is some evidence that key people within the agency are beginning to listen. Lennard Fisk, NASA’s chief scientist, said recently that the agency is considering using more, but smaller, satellites to study global climatic changes. Even when he thinks small, Fisk still means pretty big. The downsized satellites would still weigh about 15,000 pounds and carry many instruments.
Critics argue that suitcase-sized satellites could do the job better, but it would take a lot of small satellites to do the job.
Therein lies the rub, said Fisk, because it would be far easier to manage one large satellite than a dozen flying in a tight formation.
The debate has raged for the past decade, but the “small satellite” people are gaining momentum because of progress in reducing the size and weight of satellite instruments. Some of that progress grew out of research carried out by the Strategic Defense Initiative Organization, the so-called Star Wars program.
“We’re going to have 1,000-pound satellites that will be able to do what a 20,000-pound satellite could do 10 years ago,” Michael Griffin, head of technology development for the Star Wars program, told the conference.
The next generation of space instruments will include some that are incredibly small. Many satellites use cameras, called star trackers, to maintain their proper orientation by locking onto specific stars. Some star trackers are about the size of a video camera, but Lawrence Livermore Laboratory has built one that could fit inside a coin purse.
That kind of progress in miniaturization has opened many avenues because it means that very small satellites could be built to meet very sophisticated goals.
Scientists and students at the University of Michigan have proposed building a satellite with a radar camera pointed at the Earth that could detect seasonal equatorial swamps. The “Medsat,” as they call it, could be used for malaria control by identifying areas where mosquitoes are likely to breed.
Many other missions would be suitable for small satellites, but none of the little birds are being built because of a lack of space vehicles to launch them into orbit. That is part of the Catch-22 that the small satellite people find themselves in these days.
“There are no vehicles because there are no payloads,” said UCLA’s Coleman. “And there are no payloads because there aren’t any vehicles.”
Ironically, there are vehicles available, but they will probably be destroyed. Coleman said Minuteman missiles, which are being phased out through arms reduction treaties, are ideal for launching small satellites, and the U.S. government has several hundred.
The international treaties include wording that would allow the missiles to be used for scientific research, but the Bush Administration is under pressure to destroy them. Coleman said much of that pressure comes from U.S. aerospace companies.
“Why should we let the government give them away?” and glut the market for launch systems, one aerospace engineer told Coleman as a Times reporter stood nearby.
Later, he said: “We don’t care if you use them as long as you don’t use them to put anything in orbit.”
“Great,” Coleman guffawed. “We can use them as long as we don’t do any science.”
Coleman says the small satellite proponents will win only if they can bring the cost of their programs down considerably. He said the cheapest way to get a small bird into orbit today is with a Pegasus winged rocket, which is launched from a B-52 aircraft. Even that costs about $20 million, he said.
“We have to get the cost down to below $2 million,” Coleman said.
That would make small satellites more competitive. A lot of them could be launched for the cost of the $1.4-billion Galileo mission, or the even costlier Hubble Space Telescope, which orbits the Earth with a flawed optical system.
