Update November 7, 2014: NASA scientists at the Jet Propulsion Laboratory in Pasadena, California, report that analyses by the MAVEN mission and other Mars-orbiting spacecraft reveal that the red planet likely enjoyed a nighttime meteor shower due to the comet. Thousands of shooting star likely crossed the Martian sky on the evening of October 19. The meteors kicked up enough sparks to essentially create a new layer of charged particles in the high ionosphere surrounding the red planet, according to the University of Iowa’s Don Gurnett, lead investigator on the Mars Advanced Radar for Subsurface and Ionosphere Sounding instrument on the European Space Agency’s Mars Express spacecraft.
Starry-eyed spacecraft on and around Mars have made history, capturing snapshots of a comet swinging close around the red planet. A rover image of the flyby is the first view of a comet taken from the surface of another world.
The once-in-a-million-years event unfolded on Sunday, October 19, as comet Siding Spring brushed past Mars some 87,000 miles (140,000 kilometers) above the planet’s surface. NASA, the European Space Agency (ESA), and India’s space agency made sure to protect the fleet of orbiters there, by positioning them behind the planet to shield the spacecraft from the dust flying off the comet.
The orbiters all remain active and healthy and have begun to stream the images they captured of the comet just before and after its closest approach. At this point, at least two NASA spacecraft, the Mars Exploration Rover Opportunity and the Mars Reconnaissance Orbiter, have successfully imaged the barnstorming comet as it flew past at 125,000 miles (201,000 kilometers) per hour.
High above the planet’s surface, the Mars Reconnaissance Orbiter used its high-resolution cameras to focus on the comet’s bright nucleus and the hazy coma filled with gas and dust surrounding it. The image below has a scale of 453 feet (138 meters) per pixel, revealing that the nucleus was about a third of a mile (half a kilometer) wide—about half the size of previous estimates.
Meanwhile, NASA’s Opportunity rover, which has been exploring the red planet since 2004, captured a ten-second-exposure image (below) about two-and-one-half hours before the closest approach of the comet to Mars. If the rover had waited until the comet reached its closest point to the planet, the skies would have been too bright from the approaching dawn for the rover’s camera.
“It’s excitingly fortunate that this comet came so close to Mars to give us a chance to study it with the instruments we’re using to study Mars,” said Opportunity science team member Mark Lemmon, of Texas A&M University, in a press statement.
“The views from Mars rovers, in particular, give us a human perspective because they are about as sensitive to light as our eyes would be.”
More cometary portraits are expected to be streamed in the coming days from other spacecraft orbiting Mars, including the ESA’s Mars Express and India’s Mars Orbiter Mission.
So stay tuned for more historic images!