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ZL2VAL > SPACE 04.01.04 14:02l 150 Lines 5987 Bytes #999 (0) @ WW
BID : 2A0372ZL2VAL
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Subj: Spirit homes in on Mars
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Sent: 040103/1024Z @:ZL2AB.#46.NZL.OC #:32401 [New Plymouth] FBB7.00g
From: ZL2VAL@ZL2AB.#46.NZL.OC
To : SPACE@WW
Tense Times as Spirit Closes In On Mars
By Leonard David
Senior Space Writer
posted: 06:00 am ET
02 January 2004
PASADENA, California -- Hundreds of scientists and engineers are
gathering here at the Jet Propulsion Laboratory (JPL) to take part in
the touch down of Spirit -- the first of two look-alike mobile landers.
The six-wheeled, golf-cart sized robot is to reach the surface of Mars
on Saturday, January 3, at about 8:35 p.m., Pacific Standard Time.
The spacecraft's trajectory is so precise that ground controllers opted
not to perform a correction maneuver called TCM A5, and may forgo a
final adjustment to Spirit's targeting into Gusev Crater.
Spirit's twin, Opportunity, is also on course and will reach Mars three
weeks later.
Akin to making a "hole in one" after Spirit has flown over millions of
miles, ground control team members at JPL want to make a bulls-eye
landing within Gusev Crater, a 90-mile (145-kilometer) wide feature
likely formed three to four billion years ago as a result of an
impacting asteroid.
Gusev is considered a dry and ancient lakebed, complete with a channel
system that most probably carried liquid water, or water and ice, into
the crater.
Spirit in the sky
The Gusev landscape has been eyed for years by Nathalie Cabrol, a
planetary scientist at NASA's Ames Research Center. She was a key
advocate for having a Mars Exploration Rover touch down at Gusev, and
eagerly awaits the first "ground level" panorama from Spirit?s camera.
"Yes, this is getting very close now," Cabrol told SPACE.com . "At the
present time, interestingly enough, I am not nervous at all. I guess,
there is nothing we can do except pray!"
"I find myself often thinking how big Mars should be by now in Spirit's
"eyes" and it is a wonderful thing to be thinking about," Cabrol said.
"I would like to be there, and just see Gusev becoming bigger and bigger
in the last moments before landing," she said.
Aerial show
As Spirit dives through the Martian atmosphere, a complex set of actions
must occur in rapid-fire order, such as: Unfurling a critical parachute,
heatshield separation, radar scans of the approaching terrain,
retro-rocket firings, and the inflation of a huge set of airbags to
cushion the lander from repeat bounces before coming to full-stop on Mars.
To a person standing on the surface of Mars, that aerial show would be
an eye-catcher for sure.
"I wish I could be sitting on Gusev floor and see Spirit landing,
bouncing and finally come to rest on this place I have been thinking
about so much in the past 13 years," Cabrol said. "With God's help, in
few days from now, we will see the first images of Gusev and I feel
extremely privileged. For a planetary geologist, and for the time being,
this is as close as one can get to being in the field on Mars."
First signal
As Spirit hurdles toward Gusev Crater, the spacecraft will initially
communicate with Earth through a series of simple tones, letting
controllers on Earth know the craft has completed various phases of its
entry, descent, and landing.
The Deep Space Network (DSN) antennas on Earth could hear from Spirit
Saturday night, but may not receive the first signal from a healthy
spacecraft until Sunday evening.
Within the first 24 hours, Spirit will have several chances to
communicate with Earth both directly to the DSN and through NASA's Mars
Global Surveyor orbiter and NASA's Odyssey orbiter.
Both orbiters are now circling Mars, collecting science about the
planet. They will each fly over Spirit's landing site within Gusev
Crater, throughout the mission.
Growing planetary junkyard
Meanwhile, the enigmatic world appears to have claimed yet another
robotic explorer. Mum's the word from the British-built Beagle 2. It
dropped onto Mars? surface more than a week ago.
Repeated attempts to contact the lander have not been successful. Beagle
2 was targeted to land on Isidis Planitia, a large flat region that
overlies the boundary between the ancient highlands and the northern
plains.
While the British stiff-upper-lip is clearly in full bloom, the chances
that the impressive science package is alive and well seem to be fading
away, day by day.
If lost to Mars, the Beagle is one more piece of hardware heaped atop a
growing planetary junkyard of earlier failed U.S. and Russian Mars
missions that dot the planet.
"Death Planet"
"Mars has been a most daunting destination. Some, including myself, call
it the "Death Planet"," noted Edward Weiler, associate administrator for
NASA?s space science programs during a recent press briefing. "Just
getting to Mars is hard, but landing is even more so," he added.
NASA's Deep Space Network has contributed search time for the missing
lander. But now the DSN is increasingly busier handling the links for
both Spirit, as well as the NASA Stardust mission that is closing in on
Comet Wild-2 for a January 2 flyby.
The next opportunity for retrieval of a signal from Beagle 2 will be
with the European Space Agency?s (ESA) Mars Express in the New Year.
ESA's Mars Express is the orbiter that deployed the Beagle 2 and is now
circling the planet.
ESA ground teams recently nudged the Mars Express from an equatorial
orbit into a polar orbit around Mars.
That change of orbit will allow increasingly closer looks at the Beagle
2 landing site.
If Beagle 2 did successfully make it to the surface of the red planet
intact, the reduced distance, the ideal angle of overflight and the
pre-tested communications link between the 'mother' craft and its 'baby'
Beagle 2 will increase the probability of catching signals from the
lander.
=========================
73 de Alan, (Sysop ZL2AB).
AX25:ZL2VAL@ZL2AB.#46.NZL.OC
APRS:!3903.34S/17406.45E]
IP :zl2val@qsl.net
Message timed: 23:24 on 2004-Jan-03 (NZ local)
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Points to ponder
~~~~~~~~~~~~~~~~
Ambition is a poor excuse for not having enough sense to be lazy.
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