- On January 3, 1999, NASA's Mars Polar Lander roared away
from Earth on a bold mission to explore a unique region of the red planet.
The spacecraft was to gently set itself down near the border of Mars' southern
polar cap, the first ever spacecraft to study the distant world's polar
environment.
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- After months of crossing interplanetary space, Mars Polar
Lander was in the final minutes of slowing itself down, ready to make a
self-controlled touch down. It was never heard from again.
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- Nobody knows for sure exactly what occurred at journey's
end.
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- The loss of the Mars Polar Lander became a detective
story that pitted photo analysts at a super-secret spy agency and NASA
experts about the overall condition of the lost-to-Mars probe.
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- It's a saga of light and dark pixels, egos, and professional
courtesy, and a report that never saw the light of day, until now.
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- Radio silence
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- On December 3, 1999, the Mars Polar Lander was plunging
through Mars' atmosphere, headed for a soft landing on the planet's south
polar region. Once safely down the probe was to establish radio chat with
Earth and begin months of scientific work.
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- Attached to the Mars Polar Lander were a pair of small
hitchhiking devices, the Deep Space 2 Mars Microprobes -- Scott and Amundsen
-- which were to be ejected at high altitude to fall and penetrate beneath
the martian surface. They too failed to phone home.
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- Following more than a month of attempts to bring MPL
back from the dead, NASA declared the mission a failure. The loss spurred
several intense studies, both internal and external to NASA.
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- Those assessments led to a "most probable cause"
for the mishap, according to NASA.
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- Spurious signals when the trio of lander legs deployed
during descent is thought to have given a false indication to onboard smarts
of the spacecraft. It fooled itself into thinking it had landed, although
it was high above Mars.
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- The result, according to blue ribbon study groups: a
premature shutdown of the spacecraft's engines and the destruction of the
lander when it fell onto the planet. In this scenario, the probe would
have been destroyed as it smacked into the surface at 50 miles per hour
(22 meters per second), reported a Jet Propulsion Laboratory (JPL) special
review board.
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- The lander was not equipped to advise Earth controllers
what its step-by-step situation was as it zoomed in for a touch down.
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- Without any entry, descent and landing telemetry data,
there was no way to know whether the lander reached the terminal descent
propulsion phase. If it did reach this juncture, it is almost certain that
premature engine shutdown occurred, investigators concluded.
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- Enter NIMA
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- The polar environment was more severe than the landing
sites of previous missions. Far less was known about this exotic territory,
but Mars Polar Lander was billed as an "exciting and significant step"
in Mars research.
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- Mars Polar Lander's job was to focus primarily on Mars'
climate and water. It carried an instrument suite to further scientific
understanding of the climate history of the planet. It was outfitted with
a robot arm, capable of digging into Mars in a search for near-surface
ice.
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- In an early attempt to find the spacecraft, overhead
search imagery of the MPL landing site was acquired by the Mars Orbiter
Camera (MOC) system, carried by NASA's Mars Global Surveyor that had been
orbiting the planet since 1997.
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- Both JPL as manager of the MPL mission, as well as Malin
Space Science Systems, the primary contractor/operator of the MOC system,
conducted additional imagery scans to look for the lander.
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- But locating MPL, or pieces of a wrecked spacecraft,
proved inconclusive. Even if MPL sat on the surface intact it would have
been tough to detect. The MOC system was right at the very limits of its
abilities to clearly spot MPL hardware.
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- At NASA's request, a team from the National Imagery and
Mapping Agency (NIMA) -- recently renamed as the National Geospatial-Intelligence
Agency -- carried out a detailed search of the primary MPL landing area
utilizing MOC images and an array of high-tech analytical equipment.
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- Why NIMA? The agency is both a combat support as well
as national intelligence agency whose mission is to provide timely, relevant
and accurate geospatial intelligence, or GEOINT, in support of our national
security. The agency is an acclaimed leader in describing, assessing, and
visually depicting physical features on Earth. In short, it makes use of
such hush-hush tools as spy satellites.
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- The NIMA Mars sleuthing work was led by Ivar Svendsen,
who had 27 years of experience in imagery analysis, but who has since passed
away.
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- Svendsen was joined in the search for Mars Polar Lander
by the imagery expertise of James Salacain who had at the time chalked
up some 15 years of specialized duty in support of the national imagery
community.
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- Hunt for evidence
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- NIMA's task was straightforward. Use its imagery exploitation
skills and techniques for locating and making out small human-made objects
in terrestrial imagery -- but this time apply that handiwork to Mars.
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- The NIMA experts began studying dozens of Mars Global
Surveyor surface shots of the most probable MPL touch down site and surrounding
area. They were on the hunt for evidence of the lander, and other associated
hardware -- such as a cast-off descent aeroshell and parachute. These objects,
in theory, would be barely detectable by Mars Global Surveyor.
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- Also part of NIMA's investigation was gauging the different
types of materials used on Mars Polar Lander hardware, including detailed
looks at the reflective properties of the lander's solar panels.
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- In early and late 2000, the NIMA Mars surface scanning
work was done. Analysis of the search findings was wrapped up in early
2001.
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- Details of the unclassified report to NASA were provided
to SPACE.com by the National Geospatial-Intelligence Agency.
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- Three candidate sites
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- The NIMA team identified three candidate sites that had
"pixel returns" appearing to match the expected signatures of
the lander and its associated hardware. A pixel is the smallest discrete
component of an image. The greater the number of pixels-per-inch, the greater
the resolution.
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- A central feature, tagged as site two, was assessed as
the possible location of the Mars Polar Lander itself. This double "bright-spot"
signature could very well be an upright lander, sitting on the surface
with its solar panels in the deployed position, the NIMA experts reported.
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- Another pixel return, called site one, was subjected
to intense scrutiny. The NIMA analysts believed that signature may well
represent the lander's backshell, a protective cover that encased the robot
probe during atmospheric entry. In every image of site 1, there appears
to be an object visible on the surface that is brighter than the background.
This object is located nearly two miles (3-kilometers) up-range from the
possible MPL landing zone.
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- At site one, attempts to discern a large, 20-foot (6-meter)
diameter white parachute that was to remain attached to the backshell proved
problematic. The interaction of the parachute lying on the surface could
be causing that signature to become indistinct, the search team concluded.
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- Lastly, a bright pixel at site three may be indicative
of the presence of human-made materials, the NIMA researchers stated. This
locale includes a possible high-velocity impact site, including what appears
to be ground scarring, leading up to a glint. That glint could be the MPL
heat shield, the analytical team surmised.
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- The bottom line to the NIMA assessment: The Mars Polar
Lander failure likely occurred late in the spacecraft's rocket engine-powered
descent phase, or perhaps even after landing.
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- Embarrassingly wrong
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- NIMA's findings about the fate of Mars Polar Lander were
surprising to NASA.
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- NASA, in turn, reviewed the NIMA story -- a nicely bound
report, one that was complete with lots of Mars Global Surveyor imagery,
other color pictures, drawings, circles and arrows throughout.
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- According to a source familiar with the report, and taking
into account expert advice about the inner workings of Mars Global Surveyor's
MOC system, NIMA got it "embarrassingly wrong."
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- The suspect pixels probed by NIMA were identified as
electronic noise in the MOC hardware. The NIMA experts didn't detect Mars
Polar Lander, the source said, "they detected noise."
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- On March 26, 2001, a joint NASA/NIMA release was issued
by the space agency. It saluted NIMA's investigative skills, underscoring
the principal challenges in locating the missing lander. One major problem
being that the Mars Polar Lander is only somewhat larger -- about six and
a half feet across -- than the smallest objects the Mars Global Surveyor's
camera can see on the surface of Mars.
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- Furthermore, NASA made it clear that it had its own "alternative
view" of NIMA's findings. It noted that "these features could
be noise introduced by the camera system, so further work between NASA
and NIMA will be conducted to address differences of interpretation."
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- At NASA, the report was deep-sixed. The space agency
did not want to be in a position of seeing NIMA embarrassed, the source
said. "The space agency didn't want to look like it was invalidating
the work or claiming to invalidate the work of our nation's premier spy
agency."
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- Case closed? Not by a long shot.
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- Resolving the mystery
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- In a December 2002 article in Geospatial Intelligence
Review, the two NIMA analysts, Svendsen and Salacain, remain steadfast
about their observations. The signatures at the three sites studied "appeared
to be reflected light or glints" from some portion of the Mars Polar
Lander Entry, Descent and Landing system and/or the lander itself, they
asserted.
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- The NIMA team does note that spurious camera noise cannot
be ruled out. However, "the coincidental appearance of spurious noise
within the MPL primary landing site that also happened to emulate MPL-like
imagery signatures was considered unlikely."
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- In a postscript to their work, the NIMA researchers underscored
the fact that NASA's Mars Reconnaissance Orbiter (MRO), set for takeoff
in 2005, is built to take very-high-resolution snapshots of the planet's
surface. Those MRO images "may help finally resolve the mystery of
what actually happened to the MPL," they explained.
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- "If not, the MPL mystery may have to patiently away
a final and definitive investigation by a future visiting astronaut on-site
inspection team from Earth," the NIMA experts concluded.
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- The People's Camera
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- Onboard the Mars Reconnaissance Orbiter will be the HiRISE
(High Resolution Imaging Science Experiment). This super-powerful camera
will reveal small-scale objects in the debris blankets of mysterious gullies
and details of geologic structure of canyons, craters, and layered deposits.
And it could also take long shots at finding Mars Polar Lander.
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- HiRISE should be able to resolve objects a little smaller
than 3.3 feet (1 meter) diameter, said Alfred McEwen, the principal investigator
of HiRISE at the University of Arizona in Tucson. "But the Martian
surface is littered with meter-scale objects, so we could image the lander
but not be able to distinguish it from a boulder," he told SPACE.com.
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- The camera also has color imaging capability, so perhaps
a bump with an anomalous color could be detected, McEwen said. "Or
maybe there's a strewn field, perhaps including a few pieces we could detect
as pixels with anomalous colors," he added.
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- McEwen said he was not enthusiastic about taking on such
a search for Mars Polar Lander, unless there are specific locations that
are strong candidates. "But if NASA wants us to make a more extensive
search, then we will certainly cooperate."
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- HiRISE has already been dubbed "The People's Camera."
The science community and the broader public as a whole are encouraged
to participate in HiRISE targeting and data analysis. Anyone may submit
suggested image targets, as discussed on a HiRISE web site: http://hirise.lpl.arizona.edu/HiRISE/public.html
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- Technological closure
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- Tracking down the final resting spot for Mars Polar Lander
offers a form of technological closure, said Steven Jolly, chief engineer
for Mars Reconnaissance Orbiter at the Denver-based Lockheed Martin Space
Systems Company. The aerospace firm also built Mars Polar Lander, with
Jolly then serving as the company's flight operations lead for the mission.
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- "For all of us that worked on that spacecraft, we'd
love to know what went wrong," Jolly said. "All of us wished
that there was confirmation of the NIMA thoughts. That would tell us an
awful lot about the whole entry, descent, and landing sequence," he
said.
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- Jolly told SPACE.com that spacecraft engineers wrestled
with lots of scenarios that might have led to Mars Polar Lander going deaf,
dumb, and blind.
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- For one, the craft could have failed to deploy an antenna,
the only direct-to-Earth link. Then there's the view that it touched down
on the side of a hill, tipping over and also negating radio communications.
There were even intriguing, but never substantiated signals that looked
like a coherent utterances from the lander.
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- Residual hope
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- Clearly, the post-mortem "probable cause" for
Mars Polar Lander's failure must be taken into account too. Those flaws
singled out by investigative groups, Jolly said, are being solidly addressed
in the Phoenix Scout mission -- a lookalike lander scheduled to head for
Mars in 2007.
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- But there remain those that think the lander might have
survived a premature engine shutdown and free-fall "crunch down"
on Mars. "It's quite possible that the lander is in exactly the condition
that's been postulated by NIMA," Jolly said. "So it's not out
of the realm of possibility that it could be viewable."
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- "We owe it to the American public and to our own
conscious to probably take a look with the Mars Reconnaissance Orbiter,"
Jolly said. "But I don't think I would conduct a search. That would
take too much in the way of precious resources that ought to be applied
to the science that MRO represents. But certainly a few attempts should
be made."
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- Jolly admitted that there is still residual hope that
someday Mars Polar Lander will be found on the planet, sitting there fairly
intact.
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- But if this turns out to be the case, Jolly said that
raises a key question: "Why the heck didn't it work?"
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- This article is part of SPACE.com's weekly Mystery Monday
series.
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- Copyright © 2003 <http://us.rd.yahoo.com/dailynews/space/SIG=grdpua/*http://www.SPACE.com/>SPACE.com.
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