Devon Island, Nunavut, Canada
|
Haughton Crater, Devon Island
as a Mars Analog Environment
For years, planetary scientists
looking for Earthly environments similar to Mars for geological
and biological research have worked in such places as Antarctica's
Dry Valleys, Chile's Atacama Desert, Iceland's volcanic and ice
fields, California's Death Valley, Washington State's Channeled
Scabland, or Wyoming's Yellowstone National Park.
There is in reality no place
on Earth that is truly like Mars, nor is there any one place
on our planet that would quaitfy as the perfect Mars analog.
If anything, this means that nothing will replace actually going
to Mars. What then, is meant by a "Mars analog"?
Mars analogs can be defined
as locations on Earth where some environmental conditions, geological
features, biological attributes, or combinations thereof may
approximate in some specific way those to be encountered on Mars,
either at present or earlier in that planet's history, such that
new insight into the nature and evolution of Mars may be gained
from their study. But in addition to providing scientific insight
into our neighbouring world, Mars analogs can serve as valuable
test sites for the preparation of the future exploration of that
planet. |
In recent years, a team of scientists
led by MARS project scientist Dr. Pascal Lee of NASA Ames
Research Center has identified a new Mars analog site of high
promise: the 20 km-diameter Haughton Meteorite Impact Crater
and its surroundings on Devon Island, in the Canadian High
Arctic. Haughton is a site of much interest because it appears
to present not just one or a few potential Mars analog features,
but an astonishing variety of these.
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Devon Island, Queen
Elizabeth Islands, Canada |
Haughton Crater
(Click on the image for
a larger picture) |
Haughton Crater
on Devon Island
(Click on the image for
a larger picture) |
Some of the possible parallels investigated
by this NASA-supported effort, referred to by its participants
as the Haughton-Mars Project,
are listed below:
- Haughton is an impact crater,
a common and fundamental geological feature ofthe Martian surface
(and of many other planetary surfaces).
- Haughton is set in a polar
desert,a cold, relatively dry, windy, and sparsley vegetated
environment. While Devon Island is warmer and wetter than Mars
is today (and so are all other Mars analog sites on Earth), this
polar desert might be akin to Early Mars, when conditions are
thought to have been wetter and perhaps warmer.
- The center of the crater hosts
a very unusual type of terain, impact breccia permeated with
ground-ice. During the impact even, shattered Earth rocks were
thrown up high in the sky and fell back into the crater in monumental
heaps of jumbled fragments. These fragments rewelded together
under the intense heat of the impact to form impact breccia,
an analog for the "regolith" (rubble) gound on all
planets subject to meteorite bombardment. At Haughton, the impact
breccia is permeated with "permafrost" (ground-ice),
thus producing what may be the closest natural analog on Earth
to the Martian regolith.
- Shortly after its formation
23 million years ago, the Haughton crater was occupied by a lake
in which sediments were laid down. The lake has long since drained
away, but the sediments are still preserved in patches inside
the crater, slowly weathering away under the cold arctic climate.
These ancient crater lake sediments provide an analog for sediments
expected to be found in ancient impact craters on Mars that may
have once contained lakes as well. Ancient crater lakebeds on
Mars represent prime candidate sites where a well-preserved climate
record and possibly fossils might still be found.
- Haughton also provides an
opportunity to study the amount of warming of early lake waters
by impact-induced hydrothermal activity. In cold environments
such as that of the Arctic or Mars, the heat released at the
site of a freshly-formed impact crater may produce what has been
called a "phase of thermal biology", an episode of
biological development possible only under the uncharacteristically
warm temperatures immediately following an impact.
- A variety of valleys ranging
from intricate networks of channels to deep canyons dissect the
landscape at Haughton. Several types of valleys resemble those
seen on Mars. The resemblance appears to be more than superficial,
as the similarities are often specific and unique. Studying how
the varieties on Devon Island formed may provide clues to how
some valleys on Mars formed. Ultimately, such studies may help
answer the long-standing question of what happened to water on
Mars.
- The Arctic is host to a variety
of periglacial formations, geologic features such as ice mounds
and polygon fields which are indicative of the presence of ice
concentrations in the ground. Many features on Mars, especially
at high latitudes, have been hypothesized to be periglacial formations.
Haughton and the rest of Devon Island are a paradise of periglacial
landforms, providing an opportunity to explore this additional
parallel. Understanding periglacial formations at Haughton may
ultimately help recognize where ice can be found at shallow depth
on Mars.
- Haughton also offers examples
of life adapted to an extreme environment. Biological contrasts
between life inside and outside the crater have also been noted,
thus shedding light on the role of impact craters as specific
ecological niches on planets. Biological research at Haughton
may thus have profound ties with exobiological studies on Mars.
NASA's study of this Mars analog
wonderland in the cold, remote and barren reaches of Devon Island
provides a unique opportunity to study how humans will explore
Mars. The Haughton-Mars Project has already included in its two
first field seasons experiments geared towards developing the
new technologies, operational procedures, and experience in human
factors that will help realize or optimize the exploration of
Mars by humans. Field communication devices, "wearable"
information sharing systems, a coolant-free permafrost drill,
a ground-penetrating radar, robotic vehicles (developed by Carnegie
Mellon University), a field spectrometer, stereo cameras, a field
emergency medical kit (developed by NASA Kennedy Space Center),
and EVA requirements and procedures are among the human Mars exploration
items that have begun to be studied.
Such experiments will be continued
on Devon Island during the 1999 field season of the Haughton-Mars
Project, which will take NASA scientists back to Devon Island
from 21 June to 31 July, 1999. The Mars Society will participate
in this expedition to select the site where the MARS will
be set up and begin assembly of the first elements. A ground array
of solar panels may be among the first elements installed.
