Like a sweet, older sibling standing quietly to the side as the baby of the
family gets all the "ooh’s" and "aah’s," the 2001 Mars Odyssey orbiter
has blended into the background noise of cheers for the Mars Exploration
Rover discoveries. But Odyssey deserves her own praise and applause
this Saturday as she reaches a major milestone. At 5:29 p.m. PDT on May
22, 2004, Odyssey is scheduled to complete her 10,000th science mapping
orbit around the red planet.

"You know, we often take big numbers for granted in the business of
exploring space: light years of distance, terabytes of data, millions of
pounds of thrust," said Gaylon McSmith, Mars Odyssey Science Office
Manager. "Believe me, to the scientists of this project, 10,000 orbits
and everything it took to achieve this milestone is truly a BIG number.
Odyssey’s science return has been outstanding and 10,000 orbits has
provided an absolute treasure trove of information that will benefit
researchers for many years to come."

Big Orbit Numbers = Big Science

Odyssey was designed to make three major contributions to the
understanding of Mars:

  • map chemical elements and minerals on the surface of Mars to find out what "Mars is made of"
  • look for water in the shallow subsurface
  • analyze the radiation environment to determine its potential
  • effects on human health.

A Long Road to Success

Odyssey was launched from Cape Canaveral in Florida on April 7, 2001, and
began its science mapping mission on February 19, 2002.

"It has been a long road getting to this point," explained Bob
Mase, Mars Odyssey Mission Manager and former Navigation
Lead. "We followed two spacecraft losses: the 1998 Mars
Climate Orbiter and the Mars Polar Lander. After those
failures, the pressure was on. We had to plan and re-plan."

The original Mars 2001 concept consisted of two spacecraft: an
orbiter launching from Vandenburg Air Force Base in California
and a precision lander carrying a Spirit- and Opportunity-sized
rover. But, following the Mars Climate Orbiter and Mars Polar
Lander failures, the entire Mars Program as well as the Mars
2001 project were restructured to incorporate lessons learned.
The project was re-planned several times and eventually ended
up with just a single orbiter spacecraft. The spacecraft design
was still changing in the final 12 months prior to launch. "It was
an accomplishment just to get Odyssey to its new launch pad
on the opposite side of the country in Florida!" said Mase.

Relief on meeting that deadline was short-lived.While the six-month,
286-million-mile (460-million-kilometer) cruise from Earth to Mars
was largely uneventful, getting the spacecraft into orbit around Mars
(Mars orbit insertion) was arduous from a personal perspective. One
month prior to Mars orbit insertion, the 9/11 national tragedy shocked the
nation and the team. The flight team at Jet Propulsion Laboratory in
Pasadena, Calif., and their dedicated partners who operate the spacecraft
from Lockheed Martin in Denver, Colo., put their heads down and forged
ahead to achieve their goal of continuing America’s legacy of peaceful
exploration. Overcoming personal losses and concerns stemming from the
9/11 experience, the Odyssey team steadfastly prepared for arrival at
Mars and the grueling aerobraking process, which would drag the
spacecraft through the martian atmosphere to slow the spacecraft and
bring Odyssey into its desired mapping orbit.

"Every one of our 332 dives into the volatile martian atmosphere
carried the potential to burn us up," Mase explained. "Looking back on
it, the current success makes it easy to forget the pressure we were
under.The eyes of the world were upon us as a symbol of the American
spirit, and the future of the Mars Program was on our shoulders as we
were the first mission to return to Mars following two failures. The
notion that ‘you cannot fail’ still echoes in my mind," said Mase.

Fail they did not, and are still making enormous contributions to
current and future missions.

"The Mars Exploration Rover project wants to congratulate Odyssey on
doing a tremendous job on both accomplishing their own science
investigations and at the same time enabling Spirit and Opportunity to
make significant scientific discoveries from the surface of Mars," said
Richard Cook, Mars Exploration Rover former project manager. "Almost all
of our data – over 75% — is coming down through the Odyssey relay,
which is a testament to both the flexibility of the people on the
project and to the capability of the design of the spacecraft."

"Odyssey’s science return has been outstanding, and the entire team is
eager to repeat this feat of 10,000 orbits numerous times in the years
to come," said McSmith.

ODYSSEY SCIENCE INSTRUMENT HIGHLIGHTS

The Thermal Emission Imaging System (THEMIS) consists of two
cameras: one that images visible wavelengths in full color and an
infrared camera that is capable of detecting thermal and mineral
variations. To date, THEMIS has mapped 99.7% of the planet in the
infrared wavelengths and 15% in visible wavelengths. THEMIS images
have been used to identify possible recent snowpacks on martian
hillsides, to find exposed water ice near the south pole, to provide the
first complete high resolution map of the south polar layered deposits, to
map the remarkable region of Meridiani where the Opportunitiy rover
drives, and to detect ancient unweathered volcanic rocks and map
unusual mineral deposits.

The Gamma Ray Spectrometer (GRS) is a suite of three
instruments: a gamma subsystem located on the end of a
six-meter boom and two neutron subsystems, a neutron
spectrometer and a high energy neutron detector. This
collection of instruments collects gamma rays and neutrons
emitted from the planet to determine the elemental
composition of the upper meter of the martian surface. The
GRS has obtained full planet maps of the abundances of
several elements including silicon, iron, chlorine,
potassium, and thorium. GRS maps show very high
contents of water ice buried just beneath the surface over
large areas in the polar regions. GRS has also measured the
thickness of the annual carbon dioxide frost as the martian
seasons change.

The Martian Radiation Environment Experiment (MARIE) is a
radiation monitor similar to those flown on the space shuttle and the
International Space Station. MARIE has measured the background
radiation levels in orbit at Mars, and shown them to be 2 to 3 times
that around the Earth. It has also served as an outpost for monitoring
solar particle events.