The UI investigation is part of an international project aboard the European Space Agency's (ESA) Mars Express spacecraft scheduled for launch in 2003. Formally known as Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS), the joint Italian-U.S. project includes the University of Rome and NASA's Jet Propulsion Laboratory and Co-Investigator Gurnett at the University of Iowa.
Under the terms of a contract with JPL, Gurnett and his UI colleagues Rich Huff, Don Kirchner and Jim Phillips will provide the 160-foot-long antennas and related electrical instruments that the Mars-orbiting spacecraft will use to probe beneath the planet's surface, as well as study the ionosphere in the Martian skies. Also, Rockwell Collins of Cedar Rapids will collaborate with the UI in designing the radio transmitter and coupling it to the antennas.
Gurnett says that the project offers an excellent opportunity to learn what happened to the water that most scientists believe was responsible for carving the planet's spectacular canyons, some of which are longer and deeper than the Grand Canyon.
Because the planet's atmospheric pressure is extremely low, liquid water would have long ago evaporated from the surface. However, water may exist just below the surface in the form of permafrost and, farther down, as a liquid due to radioactive heating from the interior of the planet.
"Our objective is to use a low-frequency radar to penetrate the Martian surface to a depth of five kilometers -- about three miles," he says. "As the radar signal penetrates into the permafrost, we should be able to detect a strong radar reflection from the ice-water interface. The hope is that we'll be able to detect the interface and tell how much water is there."
Jeffrey Plaut, planetary geologist at JPL and co-principal investigator of MARSIS, noted, "Much of the water may lie too deep for us to detect, but the radar will be capable of showing boundaries between many kinds of geologic materials, such as layers of lava, sheets of sand, sediments, debris from impacts, and ice-rich rock and soils. Seeing into the third dimension of the crust of Mars is what makes this a unique and exciting experiment."
The other part of the project involves examining the Martian ionosphere, the electrically charged layer of the upper atmosphere that on Earth reflects radio signals back to the ground, sometimes hundreds of miles from their point of origin.
"Currently, very little is known about the ionosphere of Mars. We'll bounce radar signals off of the ionosphere and measure the time delay of the signals to learn the shape and height of the ionosphere," Gurnett says. "The result should be a major increase in our knowledge of the ionosphere around Mars."
The UI team is an excellent choice for this multidisciplinary project because, as Gurnett points out, even though radar is not his usual area of expertise, his UI research team for many years has specialized in the construction of low-frequency, space-borne radio systems.
Unlike the much-higher frequency radars normally used by airplanes and spacecraft to map surface features, the low-frequency radar provided by the UI team will penetrate deep beneath subsurface rocks and permafrost on Mars. Gurnett's team has provided low-frequency radio antennas for numerous spacecraft, including Cassini, scheduled to arrive at Saturn in 2004.
Gurnett, who was recently elected to the prestigious National Academy of Sciences, is a veteran of more than 25 major spacecraft projects, including the Voyager 1 and Voyager 2 flights to the outer planets, the Galileo mission to Jupiter, and the Cassini mission to Saturn.
He made the first observations of plasma waves and low-frequency radio emissions in the magnetospheres of Jupiter, Saturn, Uranus and Neptune and discovered lightning in the atmospheres of Jupiter and Neptune. Gurnett and his UI colleagues, engineering group manager Rich Huff, principal engineer Don Kirchner and design engineer Jim Phillips, have 111 years of spacecraft instrument design and construction between them.