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Odyssey arrived in Mars orbit in October 2001 and after firing rockets to enter orbit did a number of aerobraking maneuvers to enter it’s final orbit around Mars. Odyssey had for main goals that defined the mission:[1]

     Goal 1:  Determine if life ever arose on Mars.  This is part of the follow the water strategy of NASA for investigating possible life on Mars.  This spacecraft can remotely sense surface and subsurface water.  It also can detect minerals that are left behind when water is present.  If there is subsurface water on Mars it may exist in the form of liquid water if there are hydrothermal hot pockets like those found in Yellow Stone Park.   On Earth life is found in extreme conditions of darkness, temperature, acidity and pressure.  There is an entire chapter in this book on that very interesting subject.

     The other substance NASA looked for was Carbon.  Carbon, at least on Earth, is the back bone of our biochemistry, DNA and the physical bodies of all life.

     Goal 2:  Characterize the climate on Mars.  While conditions are Mars are not condusive to the existence of liquid water, Odyssey will look for subsurface water and ice.  Most of Mars water to day is in the form of subsurface ice in the non-polar surface ice.  Odyssey will pay particular attention to the seasonal changes of carbon dioxide in the polar regions.  Martian dust storms with can cover large areas of the planet at one time will be tracked with the goal of understanding how the come about.

     Goal 3:  Characterize the geology of Mars.   Determining the composition of Mars helps geologists understand how the landforms were created and more about the geologic history of Mars.  Mars and Earth both have volcanoes, cratering, wind, water and tectonics.   We can understand the process that have been active on Mars by comparing them to our own.

     Goal 4:  Prepare for Human Missions.   The radiation levels will affect any human missions in the future.  Odyssey took measurements on the way to Mars as well as in Mars orbit.  Beside bone loss during a long mission, radiation poses one of the greatest threats to human health.  Mars also has a highly oxidizing soil, one that breaks down organic molecules.  This will likely not be a direct threat to the astronauts, but would affect any future terraforming activities.

     Odyssey carried three main instruments to carry out it’s mission of globally mapping Mars composition.   The three instruments are THEMIS, GRS and MARIE.  Odyssey would also be the communications link for the Mars rovers Spirit and Opportunity. 

     THEMIS is Thermal Emission Imaging System and is used to map the distribution of minerals, particular those like hematite that can form only in the presence of water. 

     GRS stands for Gamma Ray Spectrometer which detects the presence of 20 different chemical elements.  Of particular in interest is the Hydrogen in the shallow subsurface which may be a hint of water.

     MARIE is the Mars Radiation Environment Experiment which as the name implies takes measurements of radiation levels.

[1] http://mars.jpl.nasa.gov/odyssey/science/

Recent Findings:

Gamma-Ray Evidence Suggests Ancient Mars Had Oceans


This 3D map superimposes gamma-ray data from Mars Odyssey's Gamma-Ray Spectrometer onto topographic data from the laser altimeter onboard the Mars Global Surveyor. The red arrow indicates the shield volcanoes of Elysium rise in northern Mars, seen obliquely to the southeast. Blue-to-violet colors at the Elysium rise and highlands stretching to the foreground of the map mark areas poor in potassium. Red-to-yellow colors mark potassium-rich sedimentary deposits in lowlands below the Mars Pathfinder landing site (PF) and Viking 1 landing site (V1).


As much as a third of Mars could have been underwater, UA scientists say

An international team of scientists who analyzed data from the Gamma Ray Spectrometer onboard NASA's Mars Odyssey reports new evidence for the controversial idea that oceans once covered about a third of ancient Mars.

"We compared Gamma Ray Spectrometer data on potassium, thorium and iron above and below a shoreline believed to mark an ancient ocean that covered a third of Mars' surface, and an inner shoreline believed to mark a younger, smaller ocean," said University of Arizona planetary geologist James M. Dohm, who led the international investigation.

"Our investigation posed the question, Might we see a greater concentration of these elements within the ancient shorelines because water and rock containing the elements moved from the highlands to the lowlands, where they eventually ponded as large water bodies?" Dohm said.

Mars Odyssey's GRS, or Gamma Ray Spectrometer, led by William Boynton of UA's Lunar and Planetary Laboratory, has the unique ability to detect elements buried as much as 1/3 meter, or 13 inches, below the surface by the gamma rays they emit. That capability led to GRS' dramatic 2002 discovery of water-ice near the surface throughout much of high-latitude Mars.

Results from Mars Odyssey and other spacecraft suggest that past watery conditions likely leached, transported and concentrated such elements as potassium, thorium and iron, Dohm said. "The regions below and above the two shoreline boundaries are like cookie cutouts that can be compared to the regions above the boundaries, as well as the total region."

The younger, inner shoreline is evidence that an ocean about 10 times the size of the Mediterranean Sea, or about the size of North America, existed on the northern plains of Mars a few billion years ago. The larger, more ancient shoreline that covered a third of Mars held an ocean about 20 times the size of the Mediterranean, the researchers estimate.

The potassium-thorium-iron enriched areas occur below the older and younger paleo-ocean boundaries with respect to the entire region, they said. The scientists used data from Mars Global Surveyor's laser altimeter for topographic maps of the regions in their study.

They are reporting their findings in the article, "GRS Evidence and the Possibility of Paleo-oceans on Mars." The article will be published in a special edition of Planetary and Space Science, which stems from a June 2007 workshop on Mars and its Earth analogs held in Trento, Italy. UA Regents' Professor Victor Baker and Boynton, and other scientists from the United States, Italy, Spain, South Korea and Canada are co-authors.

Scientific debate on the possible existence of ancient Martian oceans marked by shorelines was sparked by several studies almost 20 years ago. One such study, by Baker and colleagues at the UA Lunar and Planetary Laboratory, proposed that a few billion years ago, erupting magma unleashed floods far greater than Brazil's Amazon River. The floods ponded in the northern lowlands of Mars, forming seas and lakes that triggered relatively warmer and wetter conditions that lasted tens of thousands of years.

Scientists are driven to understand how and when water existed on Mars because water is critical to life.

Spacecraft images going back to Mariner 9 in the early 1970s and the Viking orbiters and landers later in the 1970s showed widespread evidence for a watery past for Mars. Images and other information from a flotilla of U.S. and European Mars orbiters have sharpened the details in the past decade, they added. Results from Mars Global Surveyor, Mars Odyssey, Mars Express and Mars Reconnaissance Orbiter highlight a water-and-ice-sculpted Martian landscape.

Scientists studying spacecraft images have a hard time confirming "shoreline" landforms, the researchers said, because Mars shorelines would look different from Earth's shorelines. Earth's coastal shorelines are largely a direct result of powerful tides caused by gravitational interaction between Earth and the moon, but Mars lacks a sizable moon. Another difference is that lakes or seas on Mars could have formed largely from giant debris flows and liquefied sediments. Still another difference is that Mars oceans may have been ice-covered, which would prevent wave action.

"The GRS adds key information to the long-standing oceans-on-Mars controversy," Dohm said. "But the debate is likely to continue well into the future, perhaps even when scientists can finally walk the Martian surface with instruments in hand, with a network of smarter spaceborne, airborne and ground-based robotic systems in their midst."

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