THEMIS Looks at Phobos


These animations shows three views of the Martian moon Phobos as viewed by the Mars Odyssey orbiter. The apparent motion is due to movement by Odyssey’s camera, Thermal Emission Imaging System (THEMIS) rather than moon.

Each of the three panels is a series of images taken on different dates (from top to bottom): 29 September, 2017; 15 February, 2018; and 24 April, 2019. Deimos, Mars’ other moon, can also be seen in the second panel. These are visible light images, but THEMIS is mainly used for thermal-infrared scans.

Image Credit: NASA

THEMIS, Deimos, and Phobos


These images of Phobos and Deimos, the moons of Mars, were taken by the Mars Odyssey orbiter’s THEMIS (Thermal Emission Imaging System) camera using visible-wavelength light. The apparent motion of the moon caused by the camera’s point-of-aimaim being moved during the 17-second span of the observation.

The distance to Phobos from Odyssey during the observation was about 5,600 km. The Deimos was almost 20,000 km away.

Image Credit: NASA

A Near Miss at Mars


Near MissThis graphic shows the predicted orbit of comet C/2013 A1 Siding Spring as it swings around the inner Solar System in 2014. On 19 October, the comet will pass very close to Mars. Its nucleus will miss Mars by about 132,000 km. As it flies by it, will be shedding material moving at over 50 km/s, relative to Mars and Mars-orbiting spacecraft. Even a tiny particle only 0.5 mm across moving at that speed could cause significant damage to a spacecraft.

NASA currently operates two Mars orbiters, and a third on its way, arriving in Martian orbit a month before the comet flyby. Teams operating those orbiters plan to adjust their orbits so that the spacecraft will be on the opposite side of the Mars when the comet is most likely to pass by.

Image Credit: NASA