February 2003
Frisbees in Space
by Dr. Tony Phillips
When Pete Rossoni was a kid he loved to throw Frisbees. Most kids do-it's pure
fun. But in Pete's case it was serious business. He didn't know it, but he was
practicing for his future career î in space exploration.
Grown-up Pete Rossoni is now an engineer at NASA's Goddard Space Flight Center.
His main project there is figuring out how to hurl spacecraft into orbit
Frisbee-style.
The spacecraft are small-about the size of birthday cakes. "This wouldn't work
with big satellites or heavy space ships like the shuttle," notes Rossoni. But a
cake-sized "nanosatellite" is just right.
Nanosatellites-nanosats for short--are an exciting new idea in space
exploration. Ordinary satellites tend to be heavy and expensive to launch. The
cost alone is a deterrent to space research. Nanosats, on the other hand, can
travel on a budget. For example, a Delta 4 rocket delivering a communications
satellite to orbit could also carry a few nanosats piggyback-style with little
extra effort or expense.
"Once the nanosats reach space, however, they have to separate from their ride,"
says Rossoni. And that's where Frisbee tossing comes in.
Rossoni has designed a device that can fling a nanosat off the back of its host
rocket. "It's a lot like throwing a Frisbee," he explains. "The basic mechanics
are the same. You need to impart the spin and release it cleanly-all in about a
tenth of a second." (The spinning motion is important because it allows the
science magnetometer to measure the surrounding field and lets sunlight to play
across all of the nanosat's solar panels.)
The ST5 nanosats are designed to study Earth's magnetosphere-a magnetic bubble
that surrounds our planet and protects us from the solar wind. But their primary
goal, notes Rossoni, is to test the technology of miniature satellites.
"We haven't done anything like this before," says Rossoni. Soon, however, the
concept will be tested. A trio of nanosats is slated for launch in 2004 on the
back of a rocket yet to be determined. The name of the mission, which is managed
by JPL's New Millennium Program, is Space Technology 5 (ST5).
Can groups of nanosats maintain formation as they fly through space? Will their
internal systems-miniaturized versions of full-sized satellite
components-satisfy the demands of both the harsh space environment and critical
science measurements? Is Frisbee-tossing as much fun in orbit as it is on Earth?
ST5 will provide the answers. Read about ST5 at at
http://nmp.nasa.gov/st5. Budding young
astronomers can learn more at
http://spaceplace.nasa.gov/st5/st5_tortillas1.htm.