06.21.2017 A.I. laser targeting
06.01.2017 Diagram of Lake Stratification on Mars
05.22.2017 NASA's Mars 2020 Rover Artist's Concept #1
05.15.2017 Putting Martian 'Tribulation' Behind
05.15.2017 From 'Tribulation' to 'Perseverance' on Mars
04.20.2017 Chemical Laptop Team
04.20.2017 Subcritical Water Extractor
04.20.2017 Chemical Laptop
04.20.2017 Atacama Landscape
03.30.2017 Measuring Mars' Atmosphere Loss
03.29.2017 Lifetime Achievement Award to Theisinger
03.29.2017 A Decade of Compiling the Sharpest Mars Map
03.21.2017 Break in Raised Tread on Curiosity Wheel
03.17.2017 COBALT/JPL team
03.09.2017 Back-to-Back Martian Dust Storms
02.27.2017 Swirling Dust in Gale Crater, Mars, Sol 1613
02.27.2017 Dust Devil Passes Near Martian Sand Dune
02.27.2017 Sand Moving Under Curiosity, One Day to Next
02.08.2017 Mars Reconnaissance Orbiter Observes Changes
01.26.2017 Mono Lake
01.25.2017 'Wing' Dike of Hardened Lava in New Mexico
01.25.2017 Blade-Like Martian Walls Outline Polygons
01.23.2017 Spirit And Opportunity By The Numbers
01.10.2017 Mars 2020 Rover - Artist's Concept
01.06.2017 Earth and Its Moon, as Seen From Mars
12.13.2016 Now and Long Ago at Gale Crater, Mars
12.13.2016 Where's Boron? Mars Rover Detects It
11.15.2016 Schiaparelli Impact Site on Mars, Stereo
11.03.2016 Schiaparelli Impact Site on Mars, in Color
10.17.2016 MAVEN Captures Rapid Cloud Formation
10.17.2016 Mars' Nightside Atmosphere
10.17.2016 Ultraviolet Image Near Mars' South Pole
10.17.2016 Ultraviolet Mars Reveals Cloud Formation
10.05.2016 Dust Haze Hiding the Martian Surface in 2001
10.04.2016 Test of Lander Vision System for Mars 2020
10.03.2016 A Sharpened Ultraviolet View of Mars
Phobos in Transit (M-34)Mars has two small, asteroid-sized moons named Phobos and Deimos. From the point of view of the rover, located near the equator of Mars, these moons occasionally pass in front of, or "transit," the disk of the sun. These transit events are the Martian equivalent of partial solar eclipses on Earth because the outline of the moons does not completely cover the sun (in contrast, Earth's moon does block the entire sun during a total solar eclipse). These eclipses, like those on Earth, occur in predictable "seasons" a few times each Mars year.
As part of a multi-mission campaign, NASA's Curiosity rover is observing these transits, the first of which involved the moon Phobos grazing the sun's disk. The event was observed on Martian day, or sol, 37 (September 13, 2012) using Curiosity's Mast Camera, or Mastcam, equipped with special filters for directly observing the sun. In a series of high-resolution video frames acquired at about three frames per second for about two minutes, the outline of part of Phobos blocked about five percent of the sun.
This animation shows the transit as viewed by the Mastcam 100-millimiter camera (M-100) in nine frames. Another version of the animation is available, consisting of 20 frames taken by the Mastcam 34-millimeter camera (M-34), which has about one-third the resolution of the M-100. In total, 256 frames were taken by the M-100 and 384 frames for the M-34.
The transit was also observed by Curiosity's Rover Environmental Monitoring Stations (REMS) instrument, which saw about a five percent drop in the sun's ultraviolet radiation during the event.
Mission scientists use these events to very accurately determine the orbital parameters of the Martian moons. Phobos, for example, orbits very close to Mars and is slowly spiraling in to Mars because of tidal forces. These forces change the orbital position of Phobos over time, and accurate measurements of those changes can provide information about the internal structure of that moon and how it dissipates energy. Deimos orbits much farther away and is slowly spiraling out.
NASA's Mars Exploration Rover Opportunity will also attempt to observe a different set of Phobos and Deimos transits, seen from the other side of the planet, in Meridiani Planum.
Image Credit: NASA/JPL-Caltech/MSSS