"One of the reasons we're experimenting with small satellites is that you don't have to tie up a team for decades and spend a lot of money," said Edward Montgomery, who worked on the NanoSail-D mission at NASA's Marshall Space Flight Center in Huntsville, Alabama.
"We're not being cavalier, but the benefit is that you can try and see what happens and try again and still save money over a conventional mission," he said.
Another project, the U.S. Naval Research Laboratory's TacSats program, aims in the long term to provide ground forces with real-time satellite imagery and reliable communications.
But the program is also part of a growing movement to standardize the equipment, sizes, and shapes of small satellites.
Standardization would allow companies to manufacture systems in bulk, further reducing the cost and time it takes to prepare small satellites.
In fact, the Naval Research Lab hopes to develop TacSats that can be made and launched within in days or weeks of being commissioned.
Small Eyes, Deep Impact
Small satellites might also help save our planet.
An 885-foot (270-meter) asteroid named Apophis caused a scare several years ago when prediction models showed it might hit Earth in 2029.
Scientists have now ruled out that collision. But they say Apophis will still come within our moon's orbit, and if it hits a gravitational sweet spot around the moon, it could be thrown on course to collide with Earth in 2036.
(Read about asteroids and comets targeting Earth in National Geographic magazine's August 2008 issue.)
To help pin down Apophis's orbit, the Planetary Society put out the call for spacecraft designs that could visit the asteroid. The winning entry was a 400-pound (180-kilogram) satellite named Foresight.
Without the support of a major space agency, though, Foresight will never make it into space, according to John Olds, head of SpaceWorks, the company that designed the winning satellite.
Meanwhile, the Canadian Space Agency hopes by 2010 to have launched its own $12 million surveillance satellite to find Apophis-size asteroids, comets, and meteoroids that orbit unnervingly close to Earth.
The Canadian satellite includes a 6-inch (15-centimeter) telescope. The whole satellite will be about the size of a large suitcase and weigh less than 150 pounds (70 kilograms).
"Various people have done estimates that suggest there are around a thousand near-Earth objects greater than a kilometer [a half mile] in size, and various research programs have found approaching 800," said Alan Hildebrand, principle investigator for the Canadian project.
"But with smaller objects, we're talking hundreds of thousands, maybe between 200,000 and 500,000," he said.
"We've found just over 5,000, and remember that [the space object that likely caused] the Tunguska explosion in 1908 was probably only 30 to 50 meters [100 to 160 feet] in diameter."
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