[meteorite-list] Deep Impact Collision to Give Hawaii Prime-Time Show

[Ron Baalke]

http://starbulletin.com/2005/06/12/news/story5.html

Cosmic collision to give Hawaii prime-time show
      
NASA's Deep Impact probe is set to smash into a comet on July 3

By Helen Altonn
Honolulu Star Bulletin
June 12, 2005

Hawaii residents should have front-row seats for a potentially
spectacular collision in space on July 3.

The show is the programmed crash of a detachable probe from NASA's Deep
Impact spacecraft into Comet Tempel 1 at about 7:52 p.m.

Material ejected from deep inside the crater by the impact will give
astronomers a look at what it was like when the solar system was formed
4.5 billion years ago.

"Pretty much everybody on planet Earth and all major observatories will
be looking at this at the time of encounter," said Karen Meech, member
of the Deep Impact Science Team with the University of Hawaii Institute
for Astronomy. "I'll be surprised if there is a telescope that is not
looking at it," she said in an interview.

Big Island and Maui observatories have a major role in the mission --
the first to explore a comet's interior -- as well as the Hubble and
Spitzer Space Telescopes and Chandra X-Ray Observatory.

Meech, who is coordinating all ground-based and orbital satellite
observatories, said at least 60 professional observatories are lined up
to record the event.

NASA planned it for the best viewing time from Mauna Kea, where Meech
will be with a worldwide consortium of astronomers.

An international collaboration of students and educators from the United
Kingdom, Iceland and Hawaii will collect data from the Faulkes Telescope
on Haleakala. The Advanced Electro-Optical System Telescope also will be
observing.

Events will be held on Maui, in Hilo and Waimea on the Big Island and in
Honolulu for residents who want to know more about it and participate.

The Deep Impact Spacecraft was launched from Cape Canaveral in January
with a "flyby" spacecraft and a smaller "impactor" spacecraft.

They will remain connected until about 24 hours before impact when the
three-foot, 820-pound copper probe is released into the comet's orbital
path.

The comet is racing through space at about 23,000 mph or 6.3 miles per
second, according to NASA.

It will be too faint to see without a telescope or binoculars before the
impact, but will be near the star Spica and planet Jupiter, both bright
objects.

"We are really threading the needle with this one," Rick Grammier, Deep
Impact project manager at NASA's Jet Propulsion Laboratory in Pasadena,
said in a news release. "In our quest of a great scientific payoff, we
are attempting something never done before at speeds and distances that
are truly out of this world."

The impact could create a crater ranging in size from a large house to
something bigger than Aloha Stadium and from two to 14 stories deep, the
scientists said.

But Don Yeomans, a JPL Deep Impact Mission specialist, said, "The impact
would be the astronomical equivalent of a 767 jetliner running into a
mosquito.

"It simply will not appreciably modify the comet's orbital path," he
said, adding that the comet is not a threat to Earth.

Often called dirty snowballs, comets are composed of leftover debris
from the early solar system formation, Meech said. "They preserve a
record of the chemistry and physics of what was going on then."

When astronomers look at the comets, they're not really sampling the
solar system because the surfaces have evolved, she said. "The goal is
to look beneath the older surface layers and get at the pristine material."

Space and ground-based telescopes will observe material ejected from the
comet and analyze the spectrum of reflected sunlight off of the comet to
identify elements and molecules.

The comet will be much brighter because of the sunlight reflecting off
the dust, Meech said.

For observers with the naked eye, the moment of impact may look like a
bright new star appearing, she said, pointing out it may take some time
for the dust to move away from the nucleus of the comet.

The ejected material should be brighter the next day and remain bright
perhaps for a month before it fades, she said.

Astronomers have been planning the mission for about 10 years, Meech
said. She has studied the comet for about eight years to learn more
about its orbit, size and shape to target the spacecraft.

She said the mission is limited by cost to two or three basic
instruments. The fly-by spacecraft has a high-resolution instrument with
a camera and infrared spectrometer and a medium-resolution instrument.
The impactor also has a medium-resolution instrument to record the
craft's last moments.

Studies are expected to answer basic questions about the solar system
and composition and role of comets in the Earth's early history.

All results will be aired at a scientific meeting in Brazil in early
August, Meech said.