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A powerful imager that will seek traces of past water on the Red Planet reached a key milestone this month when the team developing the Compact Reconnaissance Imaging Spectrometer for Mars — or — successfully completed its Critical Design Review.

CRISM, to be designed, built and operated by engineers and scientists at The Johns Hopkins University Applied Physics Laboratory (APL) and several partner institutions, is one of six scientific data-collecting instruments slated for NASA’s Mars Reconnaissance Orbiter, scheduled to launch in August 2005.

CRISM will be the first visible and infrared spectrometer to fly on a U.S. mission to Mars. The hi-tech electronic detective will search for “fingerprints” of minerals that form in the presence of water and might have been left by hot springs, thermal vents, lakes or ponds on Mars far back in its history, when water may have existed on the planet’s surface. CRISM will track regions on the dusty Martian surface and map them at scales as small as 60 feet (18 meters) across, from an altitude of 186 miles (300 kilometers) above the planet. The instrument will read the hundreds of colors in reflected sunlight to detect certain minerals on the surface — including the signature traces of past water.

CRISM will spend part of the orbiter’s 2-year mission covering Mars “globally” at large scales, searching for potential study spots, before taking detailed, high-resolution measurements of those specific sites. “CRISM plays a very important role in Mars exploration,” says CRISM Principal Investigator Dr. Scott Murchie, of APL. “Our data will identify areas most likely to have contained water, and areas that would make the best potential landing sites for future missions seeking traces of life or fossils on Mars.”

APL hosted CRISM’s Critical Design Review, a standard review for NASA planetary missions and projects, in early April. A 14-member panel of engineering experts from NASA’s Jet Propulsion Laboratory, Pasadena, Calif., NASA Goddard Space Flight Center, Greenbelt, Md., APL, and the aerospace industry talked to CRISM team members and examined the instrument’s designs and scientific plans. The panel concluded that the project team is ready to build its hardware and prepare CRISM for integration on the Mars Reconnaissance Orbiter.

“Scientifically and technically, we showed the review board that CRISM is on track and has a reasonable probability of success,” says Barry Tossman, CRISM project manager at APL. “We still have hard work ahead of us, but I’m sure this team will maintain its focus and progress.”

Assembly and testing on CRISM at APL will begin in late summer 2003. The team expects to ship the instrument to spacecraft-builder Lockheed Martin Aerospace, Denver, in June 2004.

The CRISM team includes expertise from universities, government agencies and small businesses in the United States and abroad. APL, which has built 60 spacecraft and more than 140 spacecraft instruments over the past four decades, also leads the effort to develop, integrate and test CRISM. CRISM’s co-investigators are top planetary scientists from Brown University, Northwestern University, Space Science Institute, Washington University in St. Louis, University of Paris, the Applied Coherent Technology Corporation, and NASA’s Goddard Space Flight Center, Ames Research Center, Johnson Space Center and Jet Propulsion Laboratory.

The Mars Reconnaissance Orbiter mission is managed by the at the Jet Propulsion Laboratory for , Washington, D.C. For more information on Mars exploration, visit . For more information on the CRISM instrument, visit .