The Stuff Between The Stars

The cosmos is laced with tiny specks of dust that decide the fate of young stars and planets. Now, NASA scientists can study the properties of far-flung space dust in the lab.

Space is a vacuum, right?

Well, almost... The space between the stars is about as empty as the best artificial vacuums created by scientists on Earth, but throughout space, the void is faintly sprinkled with gas molecules and dust grains.

These extremely sparse crumbs of matter drifting in lonely spaces between the stars may seem utterly obscure and insignificant, but they turn out to play an important role in the formation of stars and planets and many other astrophysical phenomena.

To better understand how dust grains respond to conditions in space, researchers at NASA's Marshall Space Flight Centre (MSFC) have built an apparatus in the Dusty Plasma Laboratory (DPL) that can suspend individual dust grains in a near vacuum. Once a dust grain is captured, scientists can bombard it with forms of radiation found in space and see what happens.

"What we're doing here is taking one particle and exposing it to these space-like environments and studying what happens to its (electrical) charge and other properties," said Catherine Venturini, who worked on the project for more than four years while pursuing her master's degree in physics at the University of Alabama in Huntsville.

The electrical charge on dust grains in space can, among other things, determine how small particles of dust stick together and grow into larger-sized grains that lead to the formation of stars and planets. Gravity pulls dust and gas in interstellar clouds together, but because the electrostatic force over short distances is so much stronger than gravity, even a small electrostatic repulsion between dust grains can influence (and possibly prevent) a cloud's collapse.

more information Stars in the Keyhole Nebula began to form about 3 million years ago. Tiny grains of interstellar dust influence how rapidly the nebula can collapse. They also enrich the cloud with heavy elements that are important for the formation of rocky Earth-like planets.

Also, the gas in the cloud tends to heat up as it compresses. If the cloud cannot radiate that heat away, the expansive force of the heat will resist further compression. Dust grains in the cloud are able to radiate this heat as infrared light, cooling the cloud and allowing collapse to continue.

If a nebula does collapse into a stellar system, dust provides many of the elements such as carbon, iron, magnesium and silicon that comprise the planets. (Unlike household dust, which is largely composed of dead skin cells and other organic debris, cosmic dust probably consists mostly of heavier elements.)