March 10, 2006 - The Reconnaissance Orbiter reaches Mars and establishes its orbit. It carries the most powerful camera ever to leave Earth, called HiRise. The camera takes its first four pictures on March 23, while the orbiter circles Mars at a distance of between 600 and 2,500 miles (900 to 4,000 kilometers). This initial phase of exploration lasts two weeks.
January 24, 2007 - On the third anniversary of its landing, Opportunity continues its mission of exploring the Martian terrain - 33 months longer than originally intended.
August 4, 2007 - NASA's Phoenix Mars Lander is launched successfully. Its rocket launches at Cape Canaveral Air Force Station in Florida and takes about 10 months to reach Mars. Phoenix, part of NASA's Scout program for smaller and lower-cost spacecraft, is designed to analyze soil samples and scan the Martian atmosphere after landing near its northern pole.
May 25, 2008 - The Mars Phoenix Lander completes a 296-day, 422-million-mile journey, landing near the planet's North Pole.
November 2008 - The Mars Phoenix Lander ceases communications after completing it's mission. Originally expected to last 90 Martian solar days the lander performs science for 149 of its 152 solar day lifetime.
March 22, 2010 - Last communication is heard from Spirit. The project continues to monitor for further communication. Opportunity is still operational.
September 10, 2010 - Scientists release data from the Mars Phoenix Lander suggesting that water has been weathering Mars' surface throughout history. Data also suggests that Mars' carbon dioxide atmosphere has been replenished by geologically recent volcanic eruptions providing evidence for what could be ongoing activity.
April 6, 2011 - The rover nicknamed Curiosity is unveiled. It is far larger than Spirit and Opportunity, weighing approximately 2,000 pounds (900 kilograms) and about the size of a Mini Cooper car.
May 25, 2011 - NASA scientists end attempts to regain contact with Spirit.
November 26, 2011 - The Curiosity rover launches from Cape Canaveral at 10:02am, aboard an Atlas V rocket bound for Mars. The journey is scheduled to last approximately 8.5 months.
August 6, 2012 - Curiosity successfully lands on Mars at 1:32am EDT.
September 26, 2013 - Journal Science publishes five articles regarding Mars, revealing raw data which indicates the Martian surface contains about two percent water by weight.