Space Buoys

By Dr. Tony Phillips

Congratulations!  You’re an oceanographer and you’ve just received a big grant to investigate the Pacific Ocean.  Your task: Map the mighty Pacific’s wind and waves, monitor its deep currents, and keep track of continent-sized temperature oscillations that shape weather around the world. Funds are available and you may start immediately.

Oh, there’s just one problem:  You’ve got to do this work using no more than one ocean buoy.

“That would be impossible,â€? says Dr. Guan Le of the Goddard Space Flight Center.  “The Pacific’s too big to understand by studying just one location.â€?

Yet, for Le and her space scientist colleagues, this was exactly what they have been expected to accomplish in their own studies of Earth’s magnetosphere.  The                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                 magnetosphere is an “oceanâ€? of magnetism and plasma surrounding our planet.  Its shores are defined by the outer bounds of Earth’s magnetic field and it contains a bewildering mix of matter-energy waves, electrical currents and plasma oscillations spread across a volume billions of times greater than the Pacific Ocean itself.

“For many years we’ve struggled to understand the magnetosphere using mostly single spacecraft,â€? says Le. “To really make progress, we need many spacecraft spread through the magnetosphere, working together to understand the whole.â€?

Enter Space Technology 5.

In March 2006 NASA launched a trio of experimental satellites to see what three “buoysâ€? could accomplish.  Because they weighed only 55 lbs. apiece and measured not much larger than a birthday cake, the three ST5 “micro-satellitesâ€? fit onboard a single Pegasus rocket.  Above Earth’s atmosphere, the three were flung like Frisbees from the rocket’s body into the magnetosphere by a revolutionary micro-satellite launcher.

Space Technology 5 is a mission of NASA’s New Millennium Program, which tests innovative technologies for use on future space missions.  The 90-day flight of ST5 validated several devices crucial to space buoys: miniature magnetometers, high-efficiency solar arrays, and some strange-looking but effective micro-antennas designed from principles of Darwinian evolution.  Also, ST5 showed that three satellites could maneuver together as a “constellation,â€? spreading out to measure complex fields and currents.

“ST5 was able to measure the motion and thickness of current sheets in the magnetosphere,â€? says Le, the mission’s project scientist at Goddard.  “This could not have been done with a single spacecraft, no matter how capable.â€?

The ST5 mission is finished but the technology it tested will key future studies of the magnetosphere.  Thanks to ST5, hopes Le, lonely buoys will soon be a thing of the past.

Learn more about ST5’s miniaturized technologies at Kids (and grownups) can get a better understanding of the artificial evolutionary process used to design ST5’s antennas at

This article was provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.


Space Buoys


The Space Technology 5 micro-satellites proved the feasibility of using a constellation of small spacecraft with miniature magnetometers to study Earth’s magnetosphere.

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