Shuttle Ready To Collide With Some Dust
A University of Colorado at Boulder experiment will ride into orbit on a NASA space shuttle to explore gentle collisions between particles of space dust -- a fundamental process in the formation of planets and the evolution of planetary ring systems.
The payload, dubbed Collide-2, or Collisions Into Dust Experiment Two, is part of the MACH-1 payload currently scheduled for launch on the space shuttle Endeavour on Nov. 29. Collide-2 continues the research into the dust collisions where its predecessor, Collide, left off in April 1998.
Collide-2 will perform six independent impacts of small quartz spheres into fine quartz sand. The impacts will be videotaped by two small camcorders, allowing the CU team to analyze the amount, direction and speed of dust ejected from the target trays by each impactor.
The experiment will provide data on the release of dust from the type of collision that occurs in planetary rings, and perhaps during the early phases of planet accretion.
According to Joshua Colwell, a research associate at CU-Boulder's Laboratory for Atmospheric and Space Physics, Collide has undergone improvements and modifications for its re-flight on Endeavour. The major features Collide contained all are present in Collide-2, although the projectile launchers, doors, and camera containers all were redesigned after parts of the components failed to fully operate in the original experiment.
Changing the target material also was an important priority, said Colwell. The first Collide experiment used a fine powder called JSC-1, which is similar to lunar dust. "We found that the finer material gets compacted during launch and does not behave in the way it should during the experiment." This time, only one of the six experiment boxes will contain JSC-1, while the other five will contain the grainy quartz sand.
"We've also switched from a Teflon projectile to a quartz one to make the material interactions more realistic," he said.
Collide-2 is one of three experimental programs underway at LASP to study the physics of low-energy collisions in space. Planetary ring systems, protoplanetary disks, the asteroid belt and Kuiper belt are all collisionally evolved systems. However, little is known about the dissipation of energy, the production of ejected materials and accretion in the low-speed collisions that occur between objects with low-surface gravity like planetary ring particles.
Although dust is ubiquitous in the rings of the four gaseous giant planets, how the dust is "knocked off" larger ring particles a meter or more across during their continuous collisions with each other remains a mystery.
"The rings are comprised primarily of large particles, but we see dust throughout the rings," said Colwell. "The dust is short-lived, so it acts as a very sensitive tracer of the dynamics of the larger particles. But to understand that, we need to understand each step in the life cycle of a dust particle," he said.
The enormous gravity of Earth prevents researchers from doing the type of experiment contained in Collide-2 on the ground, said Colwell. "In order for the dust to behave the way it would in the space environments being simulated, we need to get into a microgravity environment."
Collide-2 was designed and assembled primarily by LASP students, under the direction of LASP faculty, instrument assemblers and engineers. Colwell is the principal investigator and LASP researchers Larry Esposito and Mihaly Horanyi are co-investigators.
Most of the experiment's electronics were designed for the original Collide by former graduate student Barry Arbetter of CU-Boulder's electrical engineering department. Tom Calihan and Dave Crotser were the primary students involved in the re-design work for Collide-2. Other present and former CU-Boulder students who worked on Collide-2 include Andrew Diaz, Andreas Lemos, Darren Curtis, Jeff Gonder and Matt Kanter. In addition, Adrian Sikorski, an undergraduate at the Colorado School of Mines in Golden designed and built several Collide-2 components.
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Dust Gets A Charge In A Vacuum
Boulder - July 14, 2000
A small layer of dust suspended several feet above the moon's surface that was first photographed by the Lunar Surveyor spacecraft in the 1960s and later observed by Apollo astronauts has been a puzzle to some planetary scientists.