Looking up at the night sky one sees only the darkness between the stars. An area void of activity? Not exactly. This area between the star systems in our galaxy, also known as the interstellar medium, is populated with dust and hot gas. This gas is thought to have a role in planetary and solar system formation.

On November 1 NASA will launch a Black Brant IX sounding rocket carrying the X-ray Quantum Calorimeter (XQC) payload from the White Sands Missile Range, N.M., to study the role of this hot gas in solar system formation via the X-rays that it produces.

Dan McCammon, principal investigator from the University of Wisconsin, Madison, said," When this gas reaches temperatures around one million degrees and above, it begins to glow in X-rays.

This hot gas is thought to be produced by past supernova explosions and to be the initial conduit for transporting the elements formed in the center of stars throughout the galaxy, where they are necessary for making solar systems with rocky planets (everything the Earth is composed of except its hydrogen must once have been buried in the center of a star). But the details of how this happens and the distribution and composition of the very hot gas are still not well understood."

X-rays are also produced in inter-planetary space when ions from the solar wind exchange electrons with interstellar neutral hydrogen and helium passing through our solar system. XQC will use detectors called microcalorimeters to measure the heat deposited when an X-ray is absorbed by the detector.

Because the amount of energy carried by a single X-ray photon is very small, the detectors must be operated at very low temperatures (around 50 millikelvin or 1/20th of a degree above absolute zero) in order to measure the small temperature rise.

"The temperature change in a microcalorimeter can be translated into a very precise measurement of the energy of the incoming X-ray. By building up a spectrum of these measurements across a range of energies, we can determine which element produced the X-rays and much additional information on the conditions in the hot gas. We can begin to differentiate the contribution of the solar wind from that of the interstellar medium" McCammon said.

In addition, to the science that will be gained with this mission, university students are gaining invaluable hands-on experience in space research. McCammon noted that several graduate students have been assisting in the development of the experiment and will participate in the launch.

The students are NASA Space Technology Research Fellow Kelsey Morgan; graduate students Dallas Wulf and Gabriele Betancourt-Martinez ; postdoctoral researcher Felix Jaeckel; and undergraduate students Mitch Hokin, Clayton Bennet, Natalia Petre, Ethan Kay, Laura Luo and Dylan Mattox.

The 54-foot tall Black Brant IX is projected to carry the 928 pound XQC payload to an altitude of 175 miles during the 15 minute flight. The payload will descend via parachute and land about 48 miles downrange where it will be recovered.