The Spacecraft

Mars Odyssey Facts Launch Date - April 7, 2001 Arrival Date - Oct. 23, 2001 Weight - 1,671 lbs (758 kg) Cost - $135 million Mission - Two-year study of elemental composition and radiation on Mars

Is there or is there not water on Mars? There have been recent reports that have backed up both sides of the debate. Here are a few of the articles written on the subject:

• Space Daily: Has Mars Always Been a Dry World
• Space.com: Water Discovery Increase Chances of Martian Life
• CNN: Visual evidence suggests water springs on Mars

This type of interplanetary probe is amazing in how it retrieves data and relays that information millions of miles back to Earth.

Photo courtesy NASA A look at the various components of the Mars Odyssey Orbiter

The Mars Odyssey Orbiter is equipped with three scientific instruments that it uses to explore the Martian surface and atmosphere. Let's take a look at each of these:

• Gamma-ray spectrometer (GRS) - This device measures just how much hydrogen exists in the upper 3 feet of the planet's soil. The amount of hydrogen found gives scientists some evidence about the existence of water on Mars. (more information on the GRS)
• Thermal emissions imaging system (THEMIS) - This instrument identifies rock and mineral types on the planet's surface and searches for traces of hydrothermal activity. Information gathered from THEMIS helps determine safe landing sites for future missions. (more information on the THEMIS)
• Martian radiation environment experiment (MARIE) - Scientists are curious about the amount of radiation humans will be exposed to during a possible manned mission. MARIE gathers data about radiation on the planet. (more information on the MARIE instrument)