The Spirit is Willing
Nov
20, 2009
The Spirit rover has reached an
impasse. Is this the end of its
mission?
On June
10, 2003, NASA launched a robotic
science package called "Spirit" on a
mission to travel across the surface
of Mars. Less than a month later, on
July 7, 2003, its identical twin
"Opportunity" left the launch pad at
Cape Canaveral on a six month
journey to the Red Planet.
The
Spirit and Opportunity rovers were
named by Sofi Collis, age 9, in an
essay contest sponsored by the Lego
company. Hers was the winning entry
chosen from 10,000 submissions.
Spirit has been on the surface of
Mars for nearly five years. Its
original parameters were for a
mission duration of no more than
three months, however it was almost
immediately funded for an additional
five months. The fact that it has
now lasted ten times longer than
initially anticipated demonstrates
both the quality of its construction
and the quality of the information
it continues to send.
Before the Mars Exploration Rovers,
there was little known about the
surface of Mars. Viking 1 and Viking
2 soft-landed 33 years ago, but had
no capacity for movement. No other
experiments were successfully placed
on the surface until the
Pathfinder mission
with the wheeled remote vehicle
called "Sojourner," after the
nineteenth century abolitionist
Sojourner Truth. Pathfinder returned
the first
3D images
of Mars.
Spirit landed in a crater over 170
kilometers in diameter called Gusev.
The crater was chosen by the
navigation team because it appeared
to be the remains of a crater lake,
including a runoff channel.
Planetary scientists hoped that it
would provide evidence that liquid
water was able to exist out in the
open in the now
frozen desert planet's
past.
Spirit was the first space probe to
take a
high resolution
picture of another planet. After
bouncing several times across the
rocky terrain inside a nest of
airbags, when the ship finally came
to rest, just before the rover was
deployed, the cameras looked back at
the effect of its several impacts.
Its first target when it drove off
the landing platform was the
depression in the center of the
image, later called "Sleepy Hollow."
The
landing site proved to be
unrewarding. Despite what looks like
a riverbed entering Gusev crater
there was nothing but basalt,
probably the most common rock in the
Solar System. The mission team
referred to Gusev as a "basalt
prison." The only recourse was to
drive the rover to the "Columbia
Hills" (memorializing the Columbia
space shuttle tragedy) just visible
on the horizon. It meant a three
month trip. On the way, Spirit saw
what was, for Electric Universe
advocates, a significant phenomenon:
dust devils
whirling through the Martian dust.
A
press release
from the time stated: “When humans
visit Mars, they'll have to watch
out for towering electrified dust
devils." The reason for the headline
was that the dust devils seemed to
be glowing like fireflies as they
swept past the rover. In particular,
the bottoms of the whirlwinds
appeared to be continuous electric
discharges. In a previous
Picture of the Day,
it was shown that the tops of the
towering vortices are also lit up.
The
electric discharges on Mars form
what can become gigantic dust
devils. Electrically charged dust
storms, spinning at hundreds of
kilometers per hour, create intense
magnetic fields that tend to confine
charged particles and accelerate
them around the vortex at high
speed. Rapid acceleration, coupled
with high voltages in the dust
causes the electric glow.
As
Electric Universe theorist Wal
Thornhill wrote at the time:
"Spirit is moving about in an area
where there are frequent dust
devils. The dust devils are not
simply rotating winds caused by
rising warm air. They are the form
lightning takes in the thin Martian
atmosphere. So they are a great
hazard to surface craft, with their
powerful electrostatic and
electromagnetic effects. Just as the
Galileo spacecraft suffered repeated
computer glitches when it flew too
close above the plumes of the
electrical jets on Io, it is
possible that Spirit has become a
lightning rod and suffered internal
arcing – with possibly serious
consequences for its onboard
electronics. I sincerely hope not!"
Perhaps an electrical environment
that was more intense in the past is
also responsible for another of
Spirit's discoveries. As the rover
traveled through an area of deep
powder in 2006, its rear wheel
became jammed, causing it to drag.
The ground was churned up,
uncovering some
bright material
just below the surface which turned
out to be magnesium sulfate. The
presence of sulfur in the Solar
System has been suggested in past
articles as a sign of electric
discharges converting the oxygen in
water-ice to sulfur.
Spirit has been stuck in a patch of
soft ground for several months. It
is hampered by its malfunctioning
wheel, so has been unable to get
out. Mission operators are going to
attempt another maneuver that might
extricate the hapless vehicle, but
hopes are not high. If Spirit is
unable to extricate itself, the
mission will end as is. Whether it
continues to wander the hills and
valleys of Mars, or whether its
lonely vigil fades out in the lee of
a sandstone cliff, Spirit will long
be remembered by the writers of
these pages.
Stephen Smith
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