Since its early planning stages, the Mars Reconnaissance Orbiter mission has had three underlying science objectives:

1. Advance our understanding of Mars' current climate, the processes that have formed and modified the surface of the planet, and the extent to which water has played a role in surface processes.

2. Identify sites where possible effects of liquid water indicate environments that may have been conducive to biological activity or might even now harbor life.

3. Identify and characterize sites for future Mars landings.

In pursuit of these objectives, the mission will make observations and measurements to:

• Assess Mars' seasonal and time-of-day variations in water, dust and carbon dioxide in the atmosphere.
• Characterize Mars' global atmospheric structure and surface changes.
• Search for sites with evidence of water or hydrothermal activity.
• Examine the detailed stratigraphy (layers laid down over time), geologic structure and composition of Mars' surface features.
• Probe beneath the surface for evidence of subsurface layering, reservoirs of water or ice, and the internal structure of polar ice caps.
• Map and monitor the Martian gravity field to improve knowledge about Mars' crust and variations in atmospheric mass.
• Identify and characterize prospective landing sites with high potential for discoveries by future missions.

The tremendous amount of data generated by observations in many wavelengths and at high resolutions dictates the importance of the orbiter's large high-gain antenna and high-powered telecommunications system for sending the data to Earth. Nevertheless, limits on time and data capacity mean that only a small fraction of Mars can be examined at the highest resolution. The surface of Mars covers an area about the same as all the dry land on Earth. Surprises detectable with this orbiter's capable instruments could lie anywhere. Choosing where to look closely will affect what discoveries are made.

To make the most effective use of the highest-resolution capabilities, the mission's science team will employ a strategy of mixing three distinct modes of observations: daily global-scale monitoring, regional surveys and targeted high-resolution observations. The broader views will aid interpretation of the higher-resolution data and will identify additional sites for targeted observations. Some instruments can observe in more than one mode. Targeted observations may combine nearly simultaneous data collection by more than one instrument, providing context for interpreting each other's data.