A similar Los Alamos instrument aboard NASA's Lunar Prospector provided compelling evidence for water-ice at the moon's poles.
Los Alamos' neutron spectrometer will map the water table in the upper meter of the Martian soil, helping scientists to understand the climatic history of the red planet and also provide information on the location and quantity of water available for future exploration and possible colonization. The neutron spectrometer will also map the basaltic lava cover, measure the seasonal variation of dry ice snowfall at the poles and provide the necessary neutron data needed to convert the gamma ray data into elemental compositional abundances.
"We are excited and nervous about the launch. You never know what will happen -- you just hope it gets off the ground and makes it into orbit around Mars and sends us back data," said Bob Reedy a nuclear scientist at Los Alamos attending the launch who has been a part of the National Aeronautics and Space Administration Mars Gamma-Ray team for fifteen years and experienced the disappointment of the past two failed Mars missions.
Neutrons are generated when galactic cosmic rays slam into the nuclei of atoms on the planet's surface, ejecting neutrons skyward with enough energy to reach an orbiting spacecraft. Elements create their own unique distribution of neutron energy - fast, thermal or epithermal -- and these neutron flux signatures allow scientists to determine the elemental composition of the soil based upon the data received from the instruments.
The neutron spectrometer will map Mars' basaltic lava by measuring fast neutrons indicative of a major component of the lava - iron. By looking for a drop in epithermal neutron flux the scientists will locate hydrogen, most commonly in the form of water molecules, on or below the Martian surface. Hydrogen in the soil efficiently absorbs the energy from neutrons, preventing them from escaping the surface and being detected by the spectrometer.
Studying Mars will help answer questions about Earth's formation and the origin and evolution of the solar system. But Bill Feldman, Los Alamos' principal investigator on the design and construction of the neutron spectrometer says, "A paramount question of interest is, why doesn't life exist on Mars? Our understanding of what elements are necessary to foster and sustain life here on Earth exist on Mars, but yet life does not appear to have existed there. If life does not exist, nor never did exist on Mars, what makes Earth so unique that it can support life?"
Three weeks after launch as the spacecraft cruises toward Mars the neutron spectrometer will be turned on. Mars Odyssey will reach Mars in October after its 286 million-mile journey and gradually tighten its orbit to get into its mapping orbit sometime in January. At that point all instruments aboard Mars Odyssey will begin sending data about the red planet back to Earth.
The other instruments aboard the 1,600-pound spacecraft include a thermal-emission imaging system, a gamma-ray spectrometer and a radiation monitor. The Mars Odyssey mission is designed to map the mineral and chemical make-up of the Martian surface and the location of water and shallow buried ice, and for the first time study the radiation environment of the planet to gauge the risk for future astronauts.
The neutron spectrometer was designed and constructed by a team of scientists and engineers from Los Alamos' Space and Atmospheric Sciences and Space Instrumentation and System Engineering groups headed by Feldman, Ken Fuller, Steven Storms, Danny Everett, Glenn Thornton and Jerry Longmire.
Los Alamos has been flying neutron spectrometers since 1963 in support of the U.S. nuclear treaty verification program. The present design used for Mars Odyssey was developed in mid 1980 in support of the U.S. strategic defense initiative.
Los Alamos National Laboratory, a multidisciplinary research institution engaged in strategic science on behalf of national security, is operated by Los Alamos National Security, LLC, a team composed of Bechtel National, the University of California, The Babcock & Wilcox Company, and Washington Group International for the Department of Energy's National Nuclear Security Administration.
Los Alamos enhances national security by ensuring the safety and reliability of the U.S. nuclear stockpile, developing technologies to reduce threats from weapons of mass destruction, and solving problems related to energy, environment, infrastructure, health, and global security concerns.