By Day and Night, New Mars Images Reveal Lots of Ice

March 1, 2002 -- New images taken by NASA's Mars Odyssey spacecraft reveal the distant planet both by day and, for the first time, by night.

So far even these earliest images indicate the planet is chock-full of ice.

"The signal we've been getting loud and clear is there's a lot of ice on Mars," said William Boynton, principal investigator for the gamma ray spectrometer instruments on the craft, during a press conference today.

Scientists have already concluded that water exists on Mars, but these images, showing that ice may be abundant on the planet, bolster theories that life exists or once existed on Mars.

Looking for Hydrogen

Gamma ray spectrometers "read" the abundance and distribution of chemical elements and minerals on the planet's surface by measuring characteristic gamma rays reflected from different minerals and elements as cosmic rays strike the surface.

Researchers found ice on the planet's surface by detecting hydrogen, which is the main element in water. Large amounts of hydrogen were detected within the upper three feet of the planet's surface. And early assessments suggest that water ice may be distributed even beyond the planet's polar regions, where researchers had already concluded ice exists.

The images indicate that water ice is mixed in with dust and rocks under the surface for a broad region of the planet, stretching from the frozen southern polar cap north to about 60 degrees south latitude.

Jim Garvin, lead scientist of the Mars Exploration Program at NASA headquarters in Washington, D.C., emphasized the images and results are still "preliminary" and that another month or so of analysis will be needed to confirm their observations.

The Odyssey spacecraft reached Mars' orbit on Oct. 23 and began activating its scientific instruments for mapping the planet on Feb. 19.

Among its other instruments is a thermal emission imaging system that reads the range of temperatures on the planet's surface. The infrared technology on the 1,600-pound Odyssey craft doesn't depend on visual light to see and so has been able to capture the first images of Mars during nighttime.

During the Martian day, the sun heats the surface. Surface minerals then radiate this heat back to space in signature ways that can be identified and mapped by the instrument.

"I was struck by the amazing clarity and resolution of these images," said Phillip Christensen, principal investigator for the Odyssey's camera systems.

Steep Slopes, Big Boulders

The images, which cover about 20-mile-long swathes of Mars' surface, reveal steep slopes of 8,000 feet cloaked in cool shadows and large boulders warmed by the sun. Further scrutiny shows these boulders still sit on the craters they smashed out when they pelted the planet's surface millions of years ago.

Dark streaks 164 feet across can be seen on some of the cliff faces. These streaks suggest where dust may have streamed from a nearby mantle.

Christensen says he hopes the thermal imaging system might soon identify hot springs on the planet's surface as well as help in mapping future landing sites for planned Mars probes.

Data and images from the thermal imaging system and the gamma ray spectrometers are transmitted to Earth through Odyssey's newly-deployed antenna at rates as high as 110 thousand bits per second.

One instrument that has not been sending back data is the Odyssey's radiation environment experiment, which stopped functioning in August. This device was designed to measure the levels of deadly solar radiation to gauge the potential health risks to humans who might someday explore the Red Planet.

The instrument was working on the craft as Odyssey traveled to Mars and found that radiation doses during this journey would be twice the levels that astronauts now experience on the International Space Station.

Investigators are still trying to understand what happened when the tool stopped communicating in August and switched off.

Garvin said the results and images released today are just the "tip of the iceberg." The researchers hope the $300 million mission will eventually manage to map the mineral, thermal and elemental contents for the entire planet.