TUCSON, Ariz. — University of Arizona space scientists are inviting the
public to join them on campus at a special open house at the Lunar and
Planetary Laboratory (LPL) 6 p.m. – 9 p.m. next Tuesday, Oct. 23, as the
2001 Mars Odyssey spacecraft arrives at Mars.

The State of Arizona has a lot riding on the mission — namely two of the
three primary science instruments, said LPL director Michael Drake.

Drake chairs NASA’s Solar System Exploration Subcommittee, the chief U.S.
advisory committee for planetary exploration. Tuesday will be an important
moment in the history of Mars exploration, Drake told UA students last
Friday. Not only will scientists see the planet as never before, Odyssey
will help target where future rovers and landers should go in missions
leading to a 2013 Mars sample-return mission, he said.

UA planetary sciences Professor William V. Boynton heads the Gamma Ray
Spectrometer (GRS) on the Odyssey spacecraft. The GRS will for the first
time map the amount and distribution of chemical elements that make up the
martian surface.

Scientists led by Arizona State University’s Philip R. Christensen and NASA
Johnson Space Center scientists, respectively, have a thermal emission
imaging experiment and a radiation environment experiment on the Mars
Odyssey spacecraft.

Boynton and his team will be at the Tuesday evening open house in LPL’s
3rd-floor atrium to answer questions as events unfold.

Odyssey will begin the difficult and risky orbit-entry maneuver at 7:30 p.m.
Tucson time, when the spacecraft fires its main engine to slow its velocity
so it can be captured by the planet’s gravity. Then the spacecraft will
disappear behind Mars, unable to communicate with Earth for the next 20
minutes. When Odyssey re-emerges, it will transmit a radio signal back to
the NASA Deep Space Network on Earth. The network will relay that very
welcome signal to the LPL in Tucson at around 7:50 p.m.

David A. Kring, director of the NASA/UA Space Imagery Center and organizer
of the open house, said exhibits will highlight recent Mars mission
discoveries and research by several UA professors involved, including Victor
Baker, Boynton, Kring, Alfred McEwen, Robert Strom and Peter Smith. Kring
also has arranged tours of the Space Imagery Center and the "Mars Garden,"
where UA teams test their Mars mission instruments.

LPL is in the Kuiper Space Sciences Building, located east of the Flandrau
Science Center on the mall. Parking is available in lots across the mall
next to the Optical Sciences Center, and at the Second Street garage north
of the Administration Building.

The GRS during its 917 Earth-day-long geological mission will map the
amounts of the chemical elements over the entire surface of Mars —
including hydrogen, most likely in the form of water ice, buried up to a
meter (more than 3 feet) beneath the martian dust.

It is research that Boynton was ready to begin with his GRS experiment on
Mars Observer in 1993, when the spacecraft vanished as it arrived at the Red

Gamma rays are induced by cosmic rays from space and occur along with
natural radioactivity in rocks and soil. Different chemical elements emit
gamma rays at specific "signature" energies. The GRS will measure the
energies of gamma rays emitted from Mars’ surface, mapping the amount and
distribution of chemical elements over the planet.

The GRS is actually a suite of three instruments that include a gamma sensor
head and two neutron detectors.

Boynton and his team designed and built the GRS at their university
laboratories in Tucson. William Feldman of the Los Alamos National
Laboratory and Igor Mitrofanov of Russia’s Space Institute designed and
built the neutron detectors.

The GRS neutron spectrometers were turned on soon after the Odyssey
spacecraft was launched from Cape Canaveral on April 7, 2001. Scientists
opened the gamma sensor head door at the end of June and collected data to
calibrate the instrument, then closed the door at the end of August to
prepare for next week’s Mars Orbital Insertion.

All three parts of the GRS are performing well, "up to our expectations,"
team members say.

After Odyssey is safely in Mars’ orbit, mission managers will begin
"aerobraking," a technique that uses friction of Mars’ upper atmosphere to
slow the spacecraft still further, smoothing its initially elliptical orbit
into the circular orbit required to do science. Aerobraking is a 76-day
process, and transition to science orbit takes another approximately 14
days, UA team members say.

If everything goes as planned, the GRS neutron spectrometers will begin
mapping hydrogen in the planet’s surface and carbon dioxide at the poles
around mid-January 2002, they add.

The GRS is scheduled to begin mapping other elements in the martian surface
200 days after Mars orbit insertion. This operation is contingent on sun
angle, temperature and detector performance. Team members say they are
hoping to start this data collection earlier, perhaps as early as March

Boynton and his team of scientists, engineers, graduate students and
undergraduate students will run GRS science operations from the UA campus.
Scientists from other research institutions across the United States and
from several other nations are involved. The 2001 Mars Odyssey project
overall is managed for NASA by the Jet Propulsion Laboratory in Pasadena,

Boynton’s team has more details on the mission at their website,

(EDITORS: The NASA/UA Space Imagery Center will also hold open house from 1
p.m. – 4 p.m. next Saturday, October 20. In addition to the exhibits and
tours described above, UA Regents’ Professor Victor Baker will talk at 1
p.m. on "Water on Mars," and UA Professor Alfred McEwen will talk at 1:30
p.m. on "Ongoing Mars Global Surveyor Mission." Kids, their parents and
teachers are especially invited to Saturday’s event.

(VIDEO: NASA-generated Beta-footage on the 2001 Mars Odyssey Mission will be
available Friday afternoon, Oct. 19, from Vern Lamplot in UA News Services,
621-1877. For photo opportunities as exhibits are installed later this week,
contact David Kring at 621-2024.)