Spacecraft-on-a-chip to harness MEMS

by R. Colin Johnson, Contributing Editor
MEMS Investor Journal

Cornell University researchers have designed millimeter-sized spacecraft that are only microns thick and weigh just a few milligrams. These spacecraft-on-a-chip are currently just prototypes, but if their test launch goes as planned next month, MEMS will eventually be used to craft all of the "moving parts" on future spacecraft-on-a-chip.

"This is the same kind of mission as the Sputnik -- the first satellite which transmitted its internal temperature back to Earth," said engineering professor Mason Peck at Cornell University (Ithaca, New York). "Instead of temperature we are going to transmit back the angle that the sun is hitting the solar cells on the chip."

The ship will use a MEMS capacitor that is charged by the solar cell covering its front side. When the capacitor is charged, it will turn on the radio transmitter that sends a 512-bit burst and then goes back to sleep. By timing the interval between data bursts, Peck's ground crew will calculate the angle at which the sun was impacting the tiny spacecraft.

Peck's spacecraft-on-a-chip will join an area of space where there are already millions of other tiny orbiting satellites -- "space dust" particles that are measured in microns. By studying the orbital data from dust particles, Peck discovered that electromagnetic forces can overpower gravity, enabling unconventional orbits and even escape trajectories to be achieved without expending an ounce of rocket fuel.

"The reason to go small is not to save money, or to save space, or any of the typical concerns of spacecraft engineering," said Peck. "We are trying to exploit the physics of the very small for new kinds of propulsion and news kinds of spacecraft orbits. Smaller bodies are blown around by solar pressure and are also affected by electromagnetic fields."

Sandia National Laboratories is helping to construct the next generation spacecraft-on-a-chip, which will use a multi-chip module architecture, but the eventual design will be a system-on-chip with integrated MEMS components including a gyroscope for attitude control, electromagnetic coil for correcting orbit decay and solar sails for propulsion.