The Exploration of Mars
In the past few decades, the Russian and American space agencies have sent many spacecraft to Mars. Some have been a great success while others didn't even make it into space! In 1998, Japan also joined in Mars exploration with the Nozomi spacecraft.
Mariner 4 was the first mission to make it successfully to Mars. It arrived on July 14, 1965. The Mariner 4, 6, 7, & 9 missions had great success in returning images of the Red Planet and its moons, Phobos and Deimos. Between 1971-1973, the USSR sent Mars 2, 3, 4, 5, & 6 to Mars. With varying success, these orbiters and landers sent back data on the Martian atmosphere, surface, gravity, magnetosphere and temperature. In the mid 70's, the Viking missions were very successful. In all, the Viking 1 & 2 Landers returned over 1,400 images of the Martian surface! And the Viking 1 and 2 Orbiters returned 55,000 images showing surface details as small as 10 m!
After a quiet decade, Mars exploration took off again with the Mars Observer mission launched in 1992. Unfortunately, this spacecraft was lost due to explosion! NASA built upon this experience and created the successful Mars Surveyor Program which included the well-loved Mars Pathfinder and Mars Global Surveyor missions.
The new millennium has brought a new phase of Mars exploration. On April 7, 2001, the 2001 Mars Odyssey was launched. Odyssey went into orbit around Mars in October 2001, and has been mapping the planet and collecting data on the chemical and mineral composition of the Martian surface and searching for evidence of water. It is also providing vital information about potential radiation hazards for future human explorers. The European Space Agency's Mars Express mission, including the Beagle 2 lander, arrived at Mars in December 2003. NASA launched twin Mars Exploration Rovers (MER) in June and July of 2003; they landed on the Red Planet in January 2004. The two MER robots have lasted far longer than their initial intended 90-day lifetimes. As of May 2008, both were still functioning and collecting data, after more than four years on Mars.
NASA's Mars Reconnaissance Orbiter (MRO) was launched in August 2005 and went into orbit around Mars in March 2006. It is mapping the Red Planet at very high resolution, partly to help with the selection of landing sites for other future missions. The Phoenix Mars Lander, launched in August 2007, is slated to touch down near the North Pole of Mars in May 2008. Phoenix will use a robotic arm to dig up samples of Martian soil, which it will analyze in miniature laboratories it carries. A major goal of the Phoenix mission is to find water ice that scientists believe is just below the surface, based on data collected by the 2001 Odyssey spacecraft.
What of the future? NASA's Mars Science Laboratory is a large, sophisticated rover that is slated for launch in the fall of 2009. Beyond that, plans for other missions are still being formulated. We may send airplanes or balloons to roam the Martian skies, or a drilling rig to search for water and possible signs of life deep underground. Scientists also hope a sample return mission might some day bring Mars rocks back to Earth for analysis in more sophisticated laboratories than can be carried aboard spacecraft.