Yesterday, comet Siding Spring hurled past Mars at half the distance between the Earth and moon, bringing a massive cloud of dust along with it. To protect its space-based assets, space agencies employed precautionary measures, and they appear to have worked.
Top image: NASA.
The comet made its closest approach to Mars at 2:27 p.m. ET on October 19th, zipping past at 125,000 mph (56 kilometers per second). It brushed past the Red Planet at a distance of (87,000 miles) 140,000 km, which is 10 times closer than any known comet has passed by Earth.
Credit: ESA/M. Micheli/D. Abreu.
Astronomers believe that this comet, which was named after the Australian observatory that discovered it, is a first-time visitor to the inner solar system. It's thought to have originated in the Oort Cloud more than a million years ago.
Image: A shot of the comet as seen by the Opportunity Rover (the fuzzy object at center). Credit: NASA/JPL-Caltech.
NASA was concerned that the comet's dusty tail could pose a threat to orbiting spacecraft, so they tweaked its satellites' orbits so that they would be behind the planet during the most treacherous part of the flyby.
"Mars will be right at the edge of the debris cloud, so it might encounter some of the particles, or it might not," NASA Mars scientist Rich Zurek said in a statement.
After the flyby, NASA confirmed that all three of its satellites — the Mars Atmosphere and Volatile Evolution (MAVEN), the Mars Reconnaissance Orbiter (MRO), and the Mars Odyssey — were unaffected.
Likewise, the European Space Agency reported that its Mars Express spacecraft are fine and that images would be downlinked on Thursday.
India's recently arrived Mars Orbiter Mission also came out without a scratch.
"We're glad the spacecraft came through, we're excited to complete our observations of how the comet affects Mars, and we're eager to get to our primary science phase," said MAVEN Principal Investigator Bruce Jakofsky of the University of Colorado, Boulder in a statement.
Indeed, though the satellites were on the far side, they still managed to collect valuable data. Astronomers have never observed an Oort cloud comet nucleus before, providing an unprecedented opportunity for study.
Check out some cool pics of the encounter here.