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

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.

COLLIDE-2 was funded by NASA’s Microgravity Sciences and Applications
Division through the Innovative Research Program and NASA’s Lewis
Research Center.

For photos and additional mission information, visit the official
website of COLLIDE-2 at