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Posted by baalke on August 8, 2006, 2:55 pm
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http://marsrovers.jpl.nasa.gov/spotlight/20060807.html
Winter Solstice on Mars: Rovers Look Forward to A Second Martian Spring
August 07, 2006
Like the fabled tortoise that, in the race with the hare, moves slowly
yet accomplishes much, NASA's Mars Exploration Rover Spirit has
continued to make progress little by little, while essentially running
in place.
Eking out a steady stream of scientific data as solar power levels have
plunged to a seasonal low during the rover's second Martian mid-winter,
Spirit has discovered meteorites that might otherwise have been missed
and completed work on a 360-degree, full-color panorama of its
surroundings. The rover has collected long-term observations of the
Martian atmosphere, rocks, and soils under varying conditions of
sunlight, temperature, and wind.
"Spirit has conducted a regular routine of scientific observations,"
said Jake Matijevic, rover engineering team chief, "though they haven't
been very extensive each day because the energy levels don't allow
that.
After the solstice, we'll turn the rover to investigate a different
part
of the surface. We'll move very carefully to preserve our tilt toward
the sun."
The winter solstice falls on Tuesday, Aug. 8, 2006, Spirit's 923rd sol,
or Martian day, of exploration. Since April, the rover has been parked
on an outcrop known as "Low Ridge Haven," tilted 11 degrees to the
north.
Opportunity Continues Trek
On the opposite side of the planet, Spirit's twin, Opportunity,
continues to advance toward Victoria Crater, the largest crater yet
visited on the surface of Mars. While exploring Martian plains north of
the equator, Opportunity, too, has experienced lower power levels
during
the southern hemisphere winter, though not to the same degree as
Spirit.
Opportunity recently arrived at another, smaller crater known as
"Beagle
Crater," which is 35 meters (115 feet) wide. Scientists plan to spend
some time examining rocks that were excavated onto the surface during
the impact that formed the crater. Opportunity is collecting full-color
panoramic images of the site.
Like Spirit, Opportunity will have more power for science operations as
the days grow longer before and after the vernal equinox on Feb. 8,
2006, when the lengths of the day and night will be equal. On Earth,
the
vernal equinox is considered the official start of spring.
No Stranger to Adversity
As the sun moves toward zenith and power levels increase, the biggest
challenge for Spirit will be mobility. Last March, Spirit's right front
wheel stopped working. Engineers safely navigated the rover to its
winter haven, in part because they had learned to drive Spirit
alternatively backward and forward on five wheels in 2004, when
the right front wheel temporarily began drawing excess power.
Using this maneuver, the rover dragged the ailing wheel behind the
vehicle, carving a trench in the sand.
Rover handlers are optimistic that Spirit will be able to explore all
but the steepest or sandiest terrain.
"I think we should be able to drive Spirit 10 to 15 meters (30 to 45
feet) a day when solar power is restored to optimum levels," observed
Matijevic. "Sandy areas are going to have to be treated as obstacles.
We'll be looking for routes that are not too rocky but that also do not
have much sand."
Looking Ahead
Bruce Banerdt, project scientist for the mission, said team members
were
looking forward to collecting more science data as a result of having
more electrical power. NASA recently agreed to extend the Mars
Exploration Rover mission for another year starting in October.
"When Spirit has sufficient energy, which may be early September, we're
thinking about turning the rover about 30 degrees to get a better look
at the bright soil churned up by the rover's right front wheel,"
Banerdt
said. "We'll look at the chemical composition to see if it's made of
sulfate salts like other deposits we've visited. We'll have excellent
data from the 13-filter, panoramic camera images to guide us to
promising targets for further study."
The ascending sun will also bring warmer temperatures - warmer, that
is,
for Mars. The coldest day of the Martian year will probably be the same
as the shortest day, said Matijevic. Unlike Earth, Mars does not have a
thick atmosphere to buffer changes in temperature. Though Spirit is not
awake to measure the coldest temperatures in the middle of the night,
models estimate that Spirit's solar panels have recently experienced
frigid temperatures of about -104 degrees C (-155 F.).
Location, however, does make a difference. Being stationed on a
heat-absorbing rock has probably kept the rover slightly warmer than it
would have been out on the sands of the "Inner Basin," he added.
Though surviving on Mars is always a challenge, there have been no
surprises this winter. Energy levels and operating temperatures have
been in agreement with what engineers predicted. "Our experiences this
winter are very similar to what we experienced last winter," said
Matijevic.
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Posted by Landy on August 8, 2006, 7:17 pm
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baalke@earthlink.net wrote:
> http://marsrovers.jpl.nasa.gov/spotlight/20060807.html
> The winter solstice falls on Tuesday, Aug. 8, 2006, Spirit's 923rd sol,
> or Martian day, of exploration.
So which hemisphere is it the winter solstice in?
It's only the Winter solstice on half of Mars - so the
statement that it is "winter solstice on Mars" is not possible.
cheers
Bill
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Posted by Curt Welch on August 8, 2006, 7:32 pm
Please log in for more thread options > baalke@earthlink.net wrote:
>
> > http://marsrovers.jpl.nasa.gov/spotlight/20060807.html
>
> > The winter solstice falls on Tuesday, Aug. 8, 2006, Spirit's 923rd sol,
> > or Martian day, of exploration.
>
> So which hemisphere is it the winter solstice in?
The one that spacecraft are in of course! They are both near the equator
but in the southern hemisphere.
From google mars:
http://www.google.com/mars/
Spacecraft: MER Spirit Rover (USA)
Location: 14.57S, 175.47E
Launched: 2003
Results: Landed successfully in January of 2004, and still running.
Spacecraft: MER Opportunity Rover (USA)
Location: 1.95S, 5.53W
Launched: 2003
Results: Landed successfully in January of 2004, and still running.
> It's only the Winter solstice on half of Mars - so the
> statement that it is "winter solstice on Mars" is not possible.
They didn't say it was THE winter solstice on ALL of Mars did they? If the
winter solstice is on half of Mars, is not the statement, "Winter Solstice
on Mars" correct?
> cheers
> Bill
--
Curt Welch http://CurtWelch.Com/
curt@kcwc.com http://NewsReader.Com/
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Posted by Landy on August 10, 2006, 7:54 pm
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Curt Welch wrote:
>
> They didn't say it was THE winter solstice on ALL of Mars did they? If the
> winter solstice is on half of Mars, is not the statement, "Winter Solstice
> on Mars" correct?
>
No it is not. "Winter solstice on Mars" is an inane statement. What
should have been said was that it is Winter solstice in the southern
hemisphere on Mars.
Unfortunately this springs from an Americocentric view of Earth as
well. You will often here that release dates for books/movies/software
etc will be quoted as "fall (AKA autumn) 2007" (or what ever year it
is). This is of course either forgetting that Earth has another
hemisphere where the seasons are opposite, or worse still springs from
the mistaken belief that seasons are the same across the globe. You
would be surprised how many people believe the latter and think that
summer is hotter because the Earth is closer to the sun.
While the original statment is perhaps forgivable in conversation over
a beer, these are supposedly scientific forums - and so we need to be
correct about things.
cheers
Bill
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Posted by robert casey on August 10, 2006, 10:39 pm
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>
> Unfortunately this springs from an Americocentric view of Earth as
> well. You will often here that release dates for books/movies/software
> etc will be quoted as "fall (AKA autumn) 2007" (or what ever year it
> is). This is of course either forgetting that Earth has another
> hemisphere where the seasons are opposite
Well, doesn't it get cold in the Summer and hot in the Winter in the
southern hemisphere? :-)
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