Earth and Mars
This composite image of Earth and Mars was created to allow viewers to gain a better understanding of the relative sizes of the two planets.
The Mars Exploration Program's Science Theme
The Mars Exploration Program is a science-driven program that seeks to understand whether Mars was, is, or can be, a habitable world. To find out, we need to understand how geologic, climatic, and other processes have worked to shape Mars and its environment over time, as well as how they interact today.
Mars is similar to Earth in many ways, having many of the same "systems" that characterize our home world. Like Earth, Mars has an atmosphere, a hydrosphere, a cryosphere and a lithosphere. In other words, Mars has systems of air, water, ice, and geology that all interact to produce the Martian environment.
What we don't know yet is whether Mars ever developed or maintained a biosphere--an environment in which life could thrive.
Four Science Goals for Mars Exploration
The key to understanding the past, present or future potential for life on Mars can be found in the four broad, overarching goals for Mars Exploration:
