This illustration provides a comparison for how big the moons of Mars appear to be, as seen from the surface of Mars, in relation to the size that Earth’s moon appears to be when seen from the surface of Earth. Deimos, at far left, and Phobos, beside it, are shown together as they actually were photographed by the Mast Camera (Mastcam) NASA’s Mars rover Curiosity on Aug. 1, 2013. (NASA/JPL-Caltech/Malin Space Science Systems/Texas A&M Univ)

The effects of changing obliquity on Mars’ climate. Mars’ current 25-degree tilt is seen at top left. At top right is a Mars that has a high obliquity, leading to ice gather at its equator while the poles point sunwards. At bottom is Mars with low obliquity, which sees its polar caps grow in size. Image: (NASA/JPL–Caltech)

Components of Beagle 2 Flight System on Mars This annotated image shows where features seen in a 2014 observation by NASA’s Mars Reconnaissance Orbiter have been interpreted as hardware from the Dec. 25, 2003, arrival at Mars of the United Kingdom’s Beagle 2 Lander. Beagle 2 was released by the European Space Agency’s Mars Express orbiter but never heard from after its expected landing.  Images from the High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter have been interpreted as showing the Beagle 2 did make a soft landing and at least partially deployed its solar panels. The 0.1-kilometer scale bar indicates a dimension of 328 feet.  The location is approximately 11.5 degrees north latitude, 90.4 degrees east latitude. The image is an excerpt from HiRISE observation ESP_037145_1915, taken June 29, 2014. Other image products from this observation are available at . The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Mars Reconnaissance Orbiter Project for NASA’s Science Mission Directorate, Washington.  Image Credit: (NASA/JPL-Caltech/Univ. of Arizona/University of Leicester)

NASA’s Mars Reconnaissance Orbiter took this photo of the Curiosity rover on Mars on Dec. 13, 2014. Image released Feb. 5, 2015 (NASA/JPL-Caltech/Univ. of Arizona)

In February 2015, NASA’s Mars Exploration Rover Opportunity approached a cumulative driving distance on Mars equal to the length of a marathon race. Image released Feb. 10, 2015. (NASA/JPL-Caltech/Univ. of Arizona)