Complex sentence: In addition to observation from Earth, some of the latest Mars information comes from five active probes on or in orbit around Mars as of 2012: 2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, Opportunity rover, and Curiosity rover.
Split into simpler sentences: In addition to observation from Earth, some of the latest Mars information comes from five active probes on or in orbit around Mars including three orbiters and two rovers. This includes 2001 Mars Odyssey, Mars Express, Mars Reconnaissance Orbiter, Opportunity rover, and Curiosity rover.