Collision Deemed Major Success
The hyper-speed demise of NASA's Deep Impact probe generated an
immense flash of light, which provided an excellent light source
for the two cameras on the Deep Impact mothership. Deep Impact
scientists theorize the 820-pound impactor vaporized deep below the
comet's surface when the two collided at 0152 July 4, at a speed of
about 10 kilometers per second (6.3 miles per second or 23,000
miles per hour).
"You can not help but get a big flash when objects meet at
23,000 miles per hour," said Deep Impact co-investigator Dr. Pete
Schultz of Brown University, Providence, RI. "The heat produced by
impact was at least several thousand degrees Kelvin and at that
extreme temperature just about any material begins to glow.
Essentially, we generated our own incandescent photo flash for less
than a second."
The flash created by the impact was just one of the visual
surprises that confronted the Deep Impact team. Preliminary
assessment of the images and data downlinked from the flyby
spacecraft have provided an amazing glimpse into the life of a
comet.
"They say a picture can speak a thousand words," said Deep
Impact Project Manager Rick Grammier of NASA's Jet Propulsion
Laboratory, Pasadena, CA. "But when you take a look at some of the
ones we captured in the early morning hours of July 4, 2005 I think
you can write a whole encyclopedia."
At a news conference held later on July 4, Deep Impact team
members displayed a movie depicting the final moments of the
impactor's life. The final image from the impactor was transmitted
from the short-lived probe three seconds before it met its fiery
end.
"The final image was taken from a distance of about 30
kilometers (18.6 miles) from the comet's surface," said Deep Impact
Principal Investigator Dr. Michael A'Hearn of the University of
Maryland, College Park. "From that close distance we can resolve
features on the surface that are less than 4 meters (about 13 feet)
across. When I signed on for this mission I wanted to get a
close-up look at a comet, but this is ridiculous… in a great
way."
The Deep Impact scientists are not the only ones taking a close
look at their collected data. The mission's flight controller team
is analyzing the impactor's final hours of flight. When the
real-time telemetry came in after the impactor's first rocket
firing, it showed the impactor moving away from the comet's
path.
"It is fair to say we were monitoring the flight path of the
impactor pretty closely," said Deep Impact navigator Shyam
Bhaskaran of JPL. "Due to the flight software program, this initial
maneuver moved us seven kilometers off course. This was not
unexpected but at the same time not something we hoped to see. But
then the second and third maneuvers put us right where we wanted to
be."