[meteorite-list] Mars Rover Carries Device for Underground Scouting (MSL)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 20 Oct 2011 10:35:07 -0700 (PDT)
Message-ID: <201110201735.p9KHZ72b028683_at_zagami.jpl.nasa.gov>

http://www.jpl.nasa.gov/news/news.cfm?release=2011-325

Mars Rover Carries Device for Underground Scouting
Jet Propulsion Laboratory
October 20, 2011

An instrument on NASA's Mars rover Curiosity can check for any water
that might be bound into shallow underground minerals along the rover's
path.

"If we conclude that there is something unusual in the subsurface at a
particular spot, we could suggest more analysis of the spot using the
capabilities of other instruments," said this instrument's principal
investigator, Igor Mitrofanov of the Space Research Institute, Russia.

The Mars Science Laboratory mission will use 10 instruments on Curiosity
to investigate whether the area selected for the mission has ever
offered environmental conditions favorable for life and favorable for
preserving evidence about life.

"The strength of Mars Science Laboratory is the combination of all the
instruments together," Mitrofanov added.

The Dynamic Albedo of Neutrons instrument, or DAN, will scout for
underground clues to a depth of about 20 inches (50 centimeters). The
Russian Federal Space Agency contributed it to NASA as part of a broad
collaboration between the United States and Russia in the exploration of
space. Sergey Saveliev, deputy head of the Russian Federal Space Agency,
emphasized that the cooperation on this project serves as a continuation
of the joint activities associated with the study of Mars to enhance the
scientific return to the international community in the areas of Mars
exploration and Mars knowledge. The accommodation and integration of the
Russian DAN in the U.S. Mars Science Laboratory flight and mission
systems give evidence of strengthening cooperation between the two
countries in space endeavors.

DAN will bring to the surface of Mars an enhancement of nuclear
technology that has already detected Martian water from orbit. "Albedo"
in the instrument's name means reflectance -- in this case, how original
high-energy neutrons injected into the ground bounce off atomic nuclei
in the ground. Neutrons that collide with hydrogen atoms bounce off with
a characteristic decrease in energy, similar to how one billiard ball
slows after colliding with another. By measuring the energies of the
neutrons leaking from the ground, DAN can detect the fraction that was
slowed in these collisions, and therefore the amount of hydrogen.

Oil prospectors use this technology in instruments lowered down
exploration holes to detect the hydrogen in petroleum. Space explorers
have adapted it for missions to the moon and Mars, where most hydrogen
is in water ice or in water-derived hydroxyl ions.

Mitrofanov is the principal investigator for a Russian instrument on
NASA's Mars Odyssey orbiter, the high-energy neutron detector (HEND),
which measures high energy of neutrons coming from Mars. In 2002, it and
companion instruments on Odyssey detected hydrogen interpreted as
abundant underground water ice close to the surface at high latitudes.
That discovery led to NASA's Phoenix Mars Lander going to far northern
Mars in 2008 and confirming the presence of water ice.

"You can think of DAN as a reconnaissance instrument," Mitrofanov said.
Just as Phoenix investigated what Odyssey detected, Curiosity can use
various tools to investigate what DAN detects. The rover has a soil
scoop and can also dig with its wheels. Its robotic arm can put samples
into instruments inside the rover for thorough analyses of ingredients.
Rock formations that Curiosity's cameras view at the surface can be
traced underground with DAN, enhancing the ability of scientists to
understand the geology.

The neutron detectors on Odyssey rely on galactic cosmic rays hitting
Mars as a source of neutrons. DAN can work in a passive mode relying on
cosmic rays, but it also has its own pulsing neutron generator for an
active mode of shooting high-energy neutrons into the ground. In active
mode, it is sensitive enough to detect water content as low as one-tenth
of one percent in the ground beneath the rover.

The neutron generator is mounted on Curiosity's right hip. A module with
two neutron detectors is mounted on the left hip. With pulses lasting
about one microsecond and repeated as frequently as 10 times per second,
key measurements by the detectors are the flux rate and delay time of
moderated neutrons with different energy levels returning from the
ground. The generator will be able to emit a total of about 10 million
pulses during the mission, with about 10 million neutrons at each pulse.

"We have a fixed number of about 10 million shots, so one major
challenge is to determine our strategy for how we will use them," said
Maxim Litvak, leading scientist of the DAN investigation from the Space
Research Institute.

Operational planning anticipates using DAN during short pauses in drives
and while the rover is parked. It will check for any changes or trends
in subsurface hydrogen content, from place to place along the traverse.
Because there is a low possibility for underground water ice at
Curiosity's Gale crater landing site, the most likely form of hydrogen
in the ground of the landing area is hydrated minerals. These are
minerals with water molecules or hydroxyl ions bound into the
crystalline structure of the mineral. They can tenaciously retain water
from a wetter past when all free water has gone.

"We want a better understanding of where the water has gone," said
Alberto Behar, DAN investigation scientist at NASA's Jet Propulsion
Laboratory, Pasadena, Calif. "DAN fits right into the follow-the-water
strategy for studying Mars."

Mars Science Laboratory Project Scientist John Grotzinger of the
California Institute of Technology in Pasadena said, "DAN will provide
the ability to detect hydrated minerals or water ice in the shallow
subsurface, which provides immediate clues as to how the geology of the
subsurface might guide exploration of the surface. In addition, DAN can
tell us how the shallow subsurface may differ from what the rover sees
at the surface. None of our other instruments have the ability to do
this. DAN measurements will tell us about the habitability potential of
subsurface rocks and soils -- whether they contain water -- and as we
drive along, DAN may help us understand what kinds of rocks are under
the soils we drive across."

Information from DAN will also provide a ground-truth calibration for
the measurements that the gamma-ray and neutron detectors on Odyssey
have made and continue to make, all around the planet, enhancing the
value of that global data set. The team leader of Odyssey's gamma-ray
spectrometer suite, William Boynton of the University of Arizona in
Tucson, is a co-investigator on the DAN investigation, with the major
responsibility to provide DAN data products to NASA's Planetary Data
System for usage by scientists everywhere.

Besides heading the team that developed and will operate DAN, Mitrofanov
is the principal investigator for a passive neutron-detector instrument
to check for hydrated minerals on Mars' moon Phobos as part of the
Phobos Soil Return mission that Russia plans to launch in November
2011/. /"Measurements by DAN on the Mars surface will be useful for the
interpretation of Phobos data," he said.

The DAN instrument was developed by the Space Research Institute,
Moscow, in close cooperation with the N. L. Dukhov All-Russia Research
Institute of Automatics, Moscow, and the Joint Institute of Nuclear
Research, Dubna. A Russian-language website is available at
http://l503.iki.rssi.ru/ .

The Mars Science Laboratory is managed by JPL, a division of the
California Institute of Techology, Pasadena. For more information on the
mission, visit http://www.nasa.gov/msl .

Guy Webster 818-354-6278
Jet Propulsion Laboratory, Pasadena, Calif.
Guy.webster at jpl.nasa.gov

2011-325
Received on Thu 20 Oct 2011 01:35:07 PM PDT