Like Rover, Like Asteroid
From: Ron (baalke_at_earthlink.net)
Date: 10/15/04
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Date: 15 Oct 2004 15:53:20 -0700
http://marsrovers.jpl.nasa.gov/spotlight/20041011.html
Like Rover, Like Asteroid
Jet Propulsion Laboratory
October 11, 2004
Though they've never seen an asteroid, NASA's two robotic geologists
have contributed so much to planetary exploration during their
journeys
across Mars that two asteroids have now been named after them. The
rovers are the first planetary missions to be so honored.
"I think it's cool!" said Jim Erickson. "I think everyone on the
mission
feels that way. Those are our rovers. When something is named after
them, we all get the honor. And those rovers deserve respect."
Erickson is project manager for the Mars Exploration Rover Mission at
NASA's Jet Propulsion Laboratory in California.
The asteroids, named Spirit and Opportunity after NASA's Mars
Exploration Rovers, were discovered on Sept. 24, 1960 by Ingrid van
Houten-Groeneveld, Cees J. van Houten, and Tom Gehrels. The trio
spotted
the moving masses of rock on photographic plates of the night sky
taken
with telescopes at Caltech's Palomar Observatory.
Both rovers have now been exploring Mars for almost three times as
long
as originally expected.
Thousands of Years of Immortality
It took more than 40 years to name the asteroids Spirit and
Opportunity
because both are quite faint. International Astronomical Union rules
require asteroids to be observed during four separate cycles around
the
Earth and sun before they become eligible for numbering and naming,
explained Ron Baalke, a software engineer at JPL. The more
observations,
the more precisely scientists can calculate the orbit. Baalke works in
NASA's Near Earth Objects program, where he helps track and calculate
the orbits of asteroids to identify those whose paths cross that of
the
Earth.
Spirit has a diameter of 4 kilometers to 9 kilometers (2.5 miles to
5.6
miles) and Opportunity has a diameter of 3 kilometers to 7 kilometers
(1.9 miles to 4.4 miles). Van Houten-Groeneveld, who lives in the
Netherlands, proposed the name recently after the asteroids were
assigned an official number in 2002.
Both asteroids take 7.9 years to complete one orbit around the sun
between Mars and the mammoth gaseous planet Jupiter. Neither follows a
path that crosses the orbit of other planets and neither will be
knocked
out of orbit by the immense gravitational force of Jupiter. They
belong
to a small group of asteroids known as the Hilda group that have a 3:2
orbital resonance with Jupiter. This means that each time Jupiter
completes two orbits around the sun, the asteroids complete three.
The honor renders the two Mars rovers immortal in the sense that the
asteroids are in stable orbits that will last for thousands of years.
Asteroid 37452 Spirit
The asteroid Spirit travels in a path that is tilted 8 degrees from
the
plane of the solar system. Click here
<http://neo.jpl.nasa.gov/cgi-bin/db_shm?des=37452> to see an animation
of the asteroid's orbit.
Image credit: NASA/JPL
Link to Full Res
<http://marsrovers.jpl.nasa.gov/spotlight/images/Spirit-asteroid_041007163903.jpg>
Asteroid 39382 Opportunity
The asteroid Opportunity travels in a path that is tilted 3 degrees
from
the plane of the solar system. Click here
<http://neo.jpl.nasa.gov/cgi-bin/db_shm?des=39382> to see an animation
of the asteroid's orbit.
Image credit: NASA/JPL
Link to Full Res
<http://marsrovers.jpl.nasa.gov/spotlight/images/Opportunity-asteroid_041007163946.jpg>
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