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Hubble Space Telescope observations of Comet 103P/Hartley 2, taken on Sept. 25, 2010, are helping in the planning for a Nov. 4 flyby of the comet by the Deep Impact eXtended Investigation (DIXI) on NASA's EPOXI spacecraft. Credit: NASA, ESA, H. Weaver (The Johns Hopkins University/Applied Physics Lab) |
NASA is gearing up
for a close encounter with a comet next week.
The space agency's
Deep Impact spacecraft has been chasing Comet Hartley 2 for months, and on Nov.
4 the probe will come within a mere 434 miles (698 km) of its icy quarry.
The flyby ? which
will mark just the fifth time a comet has been imaged up close ? should help
scientists learn more about comet structure and evolution, as well as the early
days of the solar system, researchers said. [Photo
of Comet Hartley 2.]
"This is going
to give us the most extensive observation of a comet to date," Tim Larson
of NASA's Jet Propulsion Laboratory told reporters yesterday (Oct. 26). Larson
is project manager of Deep Impact's mission, which NASA calls EPOXI.
Deep Impact was about
5.6 million miles (9 million km) from the comet as of Oct. 26. Astronomers have
also spotted twin fireballs that may be meteors
from Comet Hartley 2.
A small, active comet
Comet
Hartley 2 completes its long, looping sojourn around the sun every 6.5
years. It was discovered in 1986 by astronomer Malcolm Hartley and made its
closest approach to Earth in 24 years on Oct. 20.
Comet Hartley 2 is
also small comet, measuring just under a mile (1.5 km) across or so. But it is
very active, researchers said, spitting lots of dust and vapor when it nears
the sun and warms up ? which is happening now.
Deep Impact has been
eyeing the comet since Sept. 5, when it took its first
photo of the icy wanderer from about 37 million miles (60 million km) away.
Since that date, the spacecraft's instruments ? two telescopes with digital
color cameras and an infrared spectrometer ? have been gathering loads of data
on the target comet.
Deep Impact has been
beaming about 2,000 images of the comet back to Earth every day since Oct. 1,
researchers said.
The close flyby, set
to take place at 10:01 a.m. EDT (1401 GMT) on Nov. 4, will give researchers
even more to chew on. The EPOXI team hopes to learn details about what
comprises Hartley 2's nucleus and compare it with other comets, scientists said.
Comets are made up of
leftovers from the solar system's early days, back when the planets were
forming from a disk of gas and dust swirling around the newly formed sun. So
seeing what's in comets could tell astronomers a lot about how the solar system
formed, researchers said.
Round 2 for Deep
Impact
This is not Deep
Impact's first comet encounter.
The spacecraft served
as the mothership for NASA's Deep Impact mission,
which intentionally crashed
a probe into Comet Tempel 1 in 2005 to study the
object's composition.
Now, the Deep Impact
spacecraft is being put to other uses ? it's tracking and studying various
celestial objects under the umbrella of NASA's broad EPOXI mission. The name is
derived from the mission's dual science investigations ? the Extrasolar Planet Observation and Characterization (EPOCh) and Deep Impact Extended Investigations (DIXI).
The spacecraft has
covered about 3.2 billion miles (5.2 billion km) in the last five years,
researchers said, but it's still going strong, closing in on Comet Hartley 2 at
speeds of about 27,000 mph (43,548 kph).
- Deep
Impact's Top 10 Comet-Crash Images
- The Best Comet Photos
of All Time
- Twin Fireballs May Be Meteors From Comet Hartley 2
