Happy Red Planet - "On the Net"
Five different missions are beaming data back to Earth.
Perhaps the most celebrated is the Mars Exploration Rover Mission <http://marsrovers.jpl.nasa.gov/home/index.html> which is now in its fourth year on Mars. It has been one of our most spectacular successes in space. You will recall that when the twin Rovers, Spirit and Opportunity, landed on Mars in January 2004 NASAs scientists and engineers were hoping their mission would last at least ninety sols, or Martian days. The Martian day <http://www.giss.nasa.gov/tools/mars24> is 24.66 hours long. The rovers have now exceeded what NASA engineers jokingly refer to as their warranty by more than twelve times. Spirit has driven seven kilometers across the Martian surface and Opportunity has logged ten kilometers. Together they have taken more than one hundred and seventy thousand photographs.
Mars Global Surveyor <http://mars.jpl.nasa.gov/mgs> is the oldest of the robots studying Mars, arriving in 1997. It circles the planet in a polar orbit every two hours, four hundred kilometers above the surface. Its longevity has led to the discovery of strong evidence that water still flows from time to time on Mars. Comparison of photographs of a gully taken in 2001, and again in 2005, show a new deposit of materials that appears to have been carried downslope by a transient flood.
Mars Odyssey,<http://mars.jpl.nasa.gov/odyssey/index.html> was designed to map the chemical and mineral composition of the Martian surface. It has led to the discovery of vast amounts of water ice just beneath the surface at the polar caps. Odyssey has also mapped the radiation environment on Mars and has served as a relay for Spirit and Opportunity, sending 85 percent of the data from the rovers to Earth.
Mars Express <http://www.esa.int/SPECIALS/Mars_Express/index.html> is the European Space Agencys Mars probe. In addition to providing high-resolution imaging and mineralogical mapping of the surface, it is also investigating the atmosphere of Mars and is making the first radar sounding measurements of the ionosphere and subsurface structure of the planet. As planned, the Mars Express mission was also to have included a lander called the Beagle 2. Alas, the Beagle never called home after landing on Mars and was declared lost. Images taken by Mars Global Surveyor suggest that the lander came down hard in a crater on Isidis Planitia.
Mars Reconnaissance Orbiter <http://www.nasa.gov/mission_pages/MRO/main/index.html> or try <http://marsprogram.jpl.nasa.gov/mro> is the newcomer on the Mars block, arriving in March of 2006. Its task is to uncover the history of water on Mars, using an array of instruments: a high-resolution camera, imaging spectrometer, context camera, ground-penetrating radar, atmospheric sounder, global color camera, radio and accelerometers.