NASA's Mars Reconnaissance Orbiter (MRO) arrived at Mars on March 10, 2006. During the next six months, MRO used hundreds of dips into the top of the Martian atmosphere to gradually adjust the size of the orbit and stabilize at nearly circular orbit at 250 to 360 km (155 to 196 miles) from the surface of the planet.
Over the past ten years, MRO has revealed in unprecedented detail a planet that held diverse wet environments billions of years ago and remains dynamic today.
One example of MRO's major discoveries is the possibility of liquid water being present seasonally on present-day Mars.
It drew on three key capabilities researchers gained from this mission: telescopic camera resolution to find features narrower than a driveway, spacecraft longevity to track seasonal changes over several Martian years, and imaging spectroscopy to map surface composition.
Other discoveries have resulted from additional capabilities of the orbiter. These include identifying underground geologic structures, scanning atmospheric layers and observing the entire planet's weather daily.
Data from MRO have improved knowledge about three distinct periods on Mars. Observations of the oldest surfaces on the planet show that diverse types of watery environments existed - some more favorable for life than others. More recently, water cycled as a gas between polar ice deposits and lower-latitude deposits of ice and snow, generating patterns of layering linked to cyclical changes similar to ice ages on Earth.
Dynamic activity on today's Mars includes fresh craters, avalanches, dust storms, seasonal freezing and thawing of carbon dioxide sheets, and summertime seeps of brine.
All six of the orbiter's science instruments remain productive in an extended mission more than seven years after completion of the mission's originally planned primary science phase.
Featured image: NASA MRO / HiRISE