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NASA:
Valentine’s date with a comet
Like two strangers in the night, a US spacecraft and a speeding comet
will dash by one another on Valentine’s Day, NASA said last week, and
skywatchers are eager to see what happens.
The Stardust-NExT spacecraft will be rapidly snapping pictures of
comet Tempel 1 as they pass at a distance of 200 kilometres. Space
experts are curious to see how a trip around the sun has affected the
surface of Tempel 1, which is about six kilometres wide and travels on
an orbit that brings it as close to the sun as Mars and as far away as
Jupiter.
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Comet Tempel 1 |
Tempel 1 was last seen in 2005 by NASA’s Deep Impact mission as the
comet was shooting toward the sun on its five-year orbit between Mars
and Jupiter. Deep Impact pummelled the comet with a special impactor
spacecraft and the material that came out was a surprise to scientists:
a cloud of fine powdery material emerged, not the water, ice and dirt
that was expected.
Deep Impact also found evidence of ice on the surface of the comet,
not just inside it.
Now space experts want to see how the comet has changed after its
tour around the scorching sun. “Every day we are getting closer and
closer and more and more excited about answering some fundamental
questions about comets,” said Joe Veverka, Stardust-NExT principal
investigator at Cornell University.
“Going back for another look at Tempel 1 will provide new insights on
how comets work and how they were put together four-and-a-half billion
years ago.”
The February 14 meetup has been a long time coming for Stardust-NExT,
or New Exploration of Tempel, NASA said.
“As of today, the spacecraft is approximately 15.3 million miles away
from its encounter,” the US space agency said in a statement. “Since
2007, Stardust-NExT executed eight flight path correction maneuvers,
logged four circuits around the sun and used one Earth gravity assist to
meet up with Tempel 1.
“Another three maneuvers are planned to refine the spacecraft’s path
to the comet.”
The rendezvous will occur 336 million kilometres away from Earth.
Initial raw images from the flyby are expected to be in NASA’s hands by
February 15.
AFP
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