NASA: Swarm of 'Smart Dust' spacraft positioned at Lagrange Point

A SWARM of "smart dust" spacecraft, positioned at a sweet spot between the Earth and the sun, could alert us to the approach of dangerous space storms well before a conventional craft can.

The first prototypes are due for launch into low-Earth orbit this year, perhaps as early as May.

Mason Peck, a mechanical engineer at Cornell University in Ithaca, New York, and his colleague Justin Atchison have designed a 1-centimetre-square spacecraft that is 25 micrometres thick and weighs under 7.5 milligrams. The craft is modelled on the dust particles that orbit the sun and are propelled by the photons streaming out from the sun.

This solar radiation pressure would have a negligible effect on normal-sized spacecraft but is significant at the millimetre scale. The grooved edges of the "spacecraft-on-a chip" deflect incoming photons in such a way as to ensure it always faces the sun.

The craft's miniature size would let it hitch a ride into space on the back of another satellite mission headed for the Lagrange point between the Earth and the sun. A Lagrange point is a kind of gravitational sweet spot, where a small object can be stationary relative to two larger objects.

The chips are essentially small solar panels with a radio antenna, and could act as a solar wind sensor (Acta Astronautica DOI: 10.1016/j.actaastro.2009.12.008).

The team envisage sending a whole swarm of these "smart dust" chips to the Lagrange point, where they would monitor the strength of the solar wind. They would also warn of any oncoming gusts of charged particles that could disrupt communications and electronic systems on Earth.

After the tiny craft has been dropped off at the Lagrange point, the effect of solar radiation moves it closer to the sun. Peck estimates that this could give an extra 13 minutes' notice of a storm compared with larger solar monitoring craft such as NASA's Advanced Composition Explorer.