Looking for water, salt:
The Gamma Ray Spectrometer (GRS)


The GRS was designed by scientists at the UA

Elements like oxygen, iron, sulfur and carbon are the building blocks of the solar system. The Gamma Ray Spectrometer experiment will find out what elements are on Mars by measuring the way they react to cosmic rays, tiny charged particles t hat come from the stars. When these cosmic rays come in contact with different elements, a certain amount of energy is released, and the three parts of the spectrometer experiment can measure this energy.

The first part will measure gamma rays, which are very high frequency waves of light, much higher than what you can see with your eyes, said Arizona scientist William Boynton, GRS team leader and cosmochemist at the UA.

"The other parts are geared toward telling us what the neutrons are like on Mars," Boynton said. "Neutrons are tiny pieces of atoms that get broken up when high-energy cosmic rays radiation strikes the surface of Mars."

The two neutron-measuring devices will be very good at measuring water or ice. Water is made of two elements, hydrogen and oxygen, and the neutron devices are very good at detecting hydrogen, even if it is three feet below the surface of Mars, Boynton sa id.

The gamma ray part of the spectrometer will be very good at finding places on Mars that could have been covered by an ocean. Oceans on Earth are made up of salt and water, and salt is made of the elements sodium and chlorine. If the gamma ray instrument finds a lot of sodium or chlorine left over in these places on Mars, then scientists will have proof that an ocean of water really did cover parts of Mars.

The spectrometer will be able to measure and detect about 20 elements that will help us find out what makes up the surface of Mars and how the geology of the planet has changed over time.

A new kind of camera: THEMIS


Above: regular camera
Below: same view by heat sensitive THEMIS

Phillip Christenson of ASU is the leader of the THEMIS team. THEMIS will map the entire surface of Mars using a camera and a thermal infrared imager, which will measure the temperature of the surface.

During the day, the sun heats up the surface of Mars. The different minerals on the surface radiate this heat back in different ways, and the thermal imager can measure this heat to figure out what minerals are present.

Using the information about minerals from the thermal imager and the information on elements from the spectrometer, the photos from the camera will help locate places with interesting minerals, places where a spacecraft could land in the future. One of t hose spacecraft could bring back a sample, said UA scientist William Boynton.

"At some point … we'll be going to Mars with the idea of picking up a rock and bringing it back. With sample return, you can find out a thousand times more about Mars than you can with remote sensing instruments."

Measuring radiation: MARIE


JPL/NASA

The MARIE experiment, designed by scientists at NASA's Johnson Space Center, will tell us how much dangerous radiation there is on Mars, so that NASA can protect astronauts who will someday visit the planet.

Radiation is energy that comes from atoms changing. It occurs naturally on the Earth and through cosmic rays in space. Radiation can come in many forms from the light and heat of the sun to the gamma rays and neutrons that the Odyssey's spectrometer will measure. High levels of radiation can be dangerous to plants and animals because they can damage living tissue.

The results of the MARIE experiment will allow NASA to design spacecraft and spacesuits that will protect astronauts from dangerous radiation. So just when will NASA send humans to Mars? UA planetary scientist Peter Smith thinks it will happen in 30 to 5 0 years.



Special Section | Friday, April 6, 2001

Prepare for liftoff


The planet Mars as seen by the Hubble Space Telescope on March 10, 1997. The photo was taken when the planet made one of it's closest passes to the Earth, about 60 million miles or 100 million km.

Arizona Daily Star

You might remember 2001 as the year Arizona went to Mars - or Mars came to Tucson. Why?

Two of the three science instruments on NASA's Odyssey mission, which is scheduled to leave for Mars tomorrow, were designed and built by Arizona scientists.

And MarsQuest - a traveling science exhibit presented by the Tucson Children's Museum in partnership with SciEnTeK-12 - will make its only appearance in the western United States at Park Place in Tucson this summer, giving lots of Arizonans the chance to experience what it's like on the red planet.

The 2001 Mars Odyssey Orbiter. Click above to see a diagram. Art by Corby J. Waste (JPL) from http://grs8.lpl.arizona.edu/images/

Mars who?

Mars is the seventh-largest planet and the fourth from the sun. Named for the Roman god of war, it's about half the size of Earth and one-and-a-half times farther away from the sun. At certain times of the year, little red Mars is the third-brightest obje ct in the night sky after the moon and Venus. Mars has two moons, a volcano three times higher than the tallest mountain on Earth, and a canyon that is longer than the United States.

Why Study mars?

Of all the planets, Mars is the most like Earth. A day on Mars is only 37 minutes longer than a day on Earth and, like our planet, Mars has seasons of summer and winter. Long ago, Mars had rivers and oceans of water. It was almost as warm as the Earth and may have had simple life forms. But something happened, and now Mars is dry and cold. Studying Mars may help us learn how planets evolve and how life formed on Earth.

Odyssey in the works

NASA'S 2001 Odyssey mission will arrive in Mars' orbit in October. The Odyssey orbiter carries three science instruments that will help us find out even more about what makes up the surface of Mars and how dangerous the planet's radiation would be for fut ure human explorers.

Mars Odyssey Orbiter Mission

Mars missions:

*1965 NASA's Mariner 4 flyby takes 22 close-up pictures of Mars.

*1969 NASA's Mariner 6 and Mariner 7 flybys take 200 high-resolution images of regions of Mars.

*1971 NASA's Mariner 9 orbits the planet for two years, mapping Mars and taking 6,900 pictures of the planet and its two moons.

*1973 Russia's Mars 5 orbits the planet and takes the first TV pictures from its surface.

*1975 NASA's Viking 1 and 2 orbiters collect 52,000 images, and landers collect 4,500 more images from the surface of Mars.

*1997 NASA's Mars Pathfinder lands on the surface of Mars and sends out a tiny rover called Sojourner, which explores the surface and examines many Mars rocks. Pathfinder collects 16,000 images of the surface of Mars from the lander and 550 images from the rover, as well as more than 15 chemical analyses of rocks and extensive data on winds and other weather factors.

* 1997 NASA's Mars Global Surveyor begins mapping the surface of Mars. Surveyor has collected more information than all other missions combined. The mission was extended in 2001 and will continue to orbit Mars, studying its magnetic field , topography and atmospheric changes.

Failed Mars missions:

More than 20 missions to Mars have ended in disaster. Seventeen Russian missions have failed. Failed U.S. missions include Mariner 3 (1964), Mariner 8 (1971), Mars Observer (1993), Mars Climate Orbiter (1999) and Mars Pol ar Lander (1999).

The 2001 Mars Odyssey is the latest mission in NASA's exploration of Mars. The primary goals of the mission are to learn about the climate, resources and evidence of past or present life on the red planet. Water is the common thread that runs through a ll of these goals.

"We have a particular science goal for Mars, and perhaps the most exciting scientific question of our day is how did life begin, not only on Earth but elsewhere," said Alfred McEwen, a planetary geologist at the University of Arizona. "On Earth, if you have liquid water, the chances of finding life are almost 100 percent. Does that apply to Mars? None of us has any idea yet."

*LIFTOFF: The Odyssey is scheduled to lift off from Cape Canaveral Air Station, Fla., tomorrow. If the weather is not good for launching, NASA can wait for a clear day until April 27. The Odyssey needs to launch between April 7 and April 27 bec ause that's when Earth and Mars are aligned in their orbits around the sun so that a spacecraft can travel to Mars with the least amount of fuel. Earth and Mars are lined up like this every 26 months. The Odyssey spacecraft will be packed inside a capsule underneath a Delta three-stage rocket. By the time the third stage of the rocket has fired, the spacecraft will be unpacked from its capsule past the orbit of the Earth.

* GETTING THERE: The Odyssey orbiter will travel between the planets for about 200 days on its way to Mars. During this time, scientists on Earth will check the instruments to make sure they're working. The thrusters on the spacecraft will be fi red during the trip. These firings are called trajectory correction maneuvers, or TCMs for short. These firings will put the spacecraft on just the right path to Mars.

*INTO MARS ORBIT: If Odyssey is launched on schedule, the main engine on the spacecraft will fire so that it is captured in the orbit of Mars Oct. 24. Over the next 76 days, thrusters on the spacecraft will fire at different times to bring the orbiter closer and closer to Mars, until it's about 250 miles from the surface. By January of 2002, the science instruments will begin taking measurements from an orbit that takes the spacecraft around Mars every two hours. The instruments will gather inf ormation for at least two years.

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