The MAVEN spacecraft will become the fourth operational spacecraft in orbit around Mars when it reaches the Red Planet in 10 months, assuming the three already there remain active. NASA’s Mars Odyssey (pictured) is the elder of the group, having launched in 2001. Launched in 2003, the European Space Agency’s Mars Express is the middle child and NASA’s Mars Reconnaissance Orbiter launched in 2005 is the young one in the neighborhood.
On the surface, two of NASA’s rovers are diligently evaluating the features and aspects of the Red Planet up close. Mars Opportunity, launched in 2003, and the Mars Science Laboratory called Curiosity is a relative new-comer, having landed at Gale Crater in August of last year.