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Starburst
region imaged by VLT
NGC 3603 is a starburst region: a cosmic
factory where stars form frantically from the nebula’s extended clouds
of gas and dust. Located 22 000 light-years away from the Sun,
it is the closest region of this kind known in our galaxy, providing
astronomers with a local test bed for studying the intense star
formation processes, very common in other galaxies, but hard to observe
in detail because of their large distance.
The newly released image, obtained with the
FORS instrument attached to one of the four 8.2-metre VLT
Unit Telescopes at Cerro Paranal, Chile, is a three-color
combination of exposures acquired through visible and near-infrared (V,
R, I) filters. This image portrays a wider field around the stellar
cluster and reveals the rich texture of the surrounding clouds of gas
and dust. The field of view is 7 arcminutes wide.
Image Credit: ESO
Spirit is
stuck for good, says NASA
As
Earth and Mars approach orbital close points and opposition, a hunk of
intelligent metal sits crippled and stuck in a sand pit on the Red
Planet. The two worlds never seemed farther apart.
 WASHINGTON
-- After six years of unprecedented exploration of the Red Planet,
NASA's Mars Exploration Rover Spirit no longer will be a fully mobile
robot. NASA has designated the once-roving scientific explorer a
stationary science platform after efforts during the past several
months to free it from a sand trap have been unsuccessful.
The
venerable robot's primary task in the next few weeks will be to
position itself to combat the severe Martian winter. If Spirit
survives, it will continue conducting significant new science from its
final location. The rover's mission could continue for several months
to years.
"Spirit is not dead; it has just entered another phase
of its long life," said Doug McCuistion, director of the Mars
Exploration Program at NASA Headquarters in Washington. "We told the
world last year that attempts to set the beloved robot free may not be
successful. It looks like Spirit's current location on Mars will be its
final resting place."
Ten months ago, as Spirit was driving
south beside the western edge of a low plateau called Home Plate, its
wheels broke through a crusty surface and churned into soft sand hidden
underneath.
After Spirit became embedded, the rover team crafted
plans for trying to get the six-wheeled vehicle free using its five
functioning wheels -the sixth wheel quit working in 2006, limiting
Spirit's mobility. The planning included experiments with a test rover
in a sandbox at NASA's Jet Propulsion Laboratory in Pasadena, Calif.,
plus analysis, modeling and reviews. In November, another wheel quit
working, making a difficult situation even worse.
Recent drives
have yielded the best results since Spirit became embedded. However,
the coming winter mandates a change in strategy. It is mid-autumn at
the solar-powered robot's home on Mars. Winter will begin in May. Solar
energy is declining and expected to become insufficient to power
further driving by mid-February. The rover team plans to use those
remaining potential drives for improving the rover's tilt. Spirit
currently tilts slightly toward the south. The winter sun stays in the
northern sky, so decreasing the southward tilt would boost the amount
of sunshine on the rover's solar panels.
"We need to lift the
rear of the rover, or the left side of the rover, or both," said Ashley
Stroupe, a rover driver at JPL. "Lifting the rear wheels out of their
ruts by driving backward and slightly uphill will help. If necessary,
we can try to lower the front right of the rover by attempting to drop
the right-front wheel into a rut or dig it into a hole."
At its
current angle, Spirit probably would not have enough power to keep
communicating with Earth through the Martian winter. Even a few degrees
of improvement in tilt might make enough difference to enable
communication every few days.
"Getting through the winter will
all come down to temperature and how cold the rover electronics will
get," said John Callas, project manager at JPL for Spirit and its twin
rover, Opportunity. "Every bit of energy produced by Spirit's solar
arrays will go into keeping the rover's critical electronics warm,
either by having the electronics on or by turning on essential heaters."
Even in a stationary state, Spirit continues scientific research.
"There's
a class of science we can do only with a stationary vehicle that we had
put off during the years of driving," said Steve Squyres, a researcher
at Cornell University and principal investigator for Spirit and
Opportunity. "Degraded mobility does not mean the mission ends
abruptly. Instead, it lets us transition to stationary science."
One
stationary experiment Spirit has begun studies tiny wobbles in the
rotation of Mars to gain insight about the planet's core. This requires
months of radio-tracking the motion of a point on the surface of Mars
to calculate long-term motion with an accuracy of a few inches.
"If
the final scientific feather in Spirit's cap is determining whether the
core of Mars is liquid or solid, that would be wonderful -- it's so
different from the other knowledge we've gained from Spirit," said
Squyres.
Tools on Spirit's robotic arm can study variations in
the composition of nearby soil, which has been affected by water.
Stationary science also includes watching how wind moves soil particles
and monitoring the Martian atmosphere.
Spirit and Opportunity
landed on Mars in January 2004. They have been exploring for six years,
far surpassing their original 90-day mission. Opportunity currently is
driving toward a large crater called Endeavor and continues to make
scientific discoveries. It has driven approximately 12 miles and
returned more than 133,000 images.
Image:
Spirit's last tracks. The view from Spirit's navigation camera shows
tracks left by the rover as it drove backward, dragging its inoperable
right-front wheel, to the location where the rover became trapped in
soft sand in April 2009.
Credit:
NASA/JPL-Caltech
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