This weekend, on Oct. 19, Comet C/2013 A1 Siding Spring is set to make its closest approach to Mars at roughly 2:27 p.m. EDT (1427 GMT). During this close encounter, Siding Spring will flyby the Red Planet at a distance of only 88,000 miles (139,500 kilometers) -- that's roughly one-third the distance from the Earth to the Moon. NASA has multiple spacecraft on or orbiting Mars currently, and they are ready to capture an unprecedented view this weekend. With the help of these vehicles, we will be able to see the first ever view of a comet flying by another planet, as seen from that planet.
NASA held a press conference this week discussing this historic flyby. Comet Siding Spring was first discovered last year by Robet H. McNaught at Australia's Siding Spring Observatory. The comet, coma and all, is believed to have as much mas as a mountain, and would fill two-thirds of the space between the Earth and Mars. Comets are cosmic time capsules, carrying with them the secrets of the early solar system. They originate from many different parts of the solar system, but what makes Comet Siding Spring and this flyby so unique is that this will the first time we capture an image of an Oort Cloud comet.
The Oort Cloud is an icy section of the outer solar system that is too far from Earth to send spacecraft, so the opportunity to image an Oort Cloud comet is pretty extraordinary. Scientists believe Comet Siding Spring first formed near Jupiter, in the early days of the solar system, before being flung out to icy edges of the solar system. It is estimated that Siding Spring's orbit brings it to the inner portions of the solar system every one to two million years, so this comet could potentially be in almost the same condition as when it formed. Thanks to advanced tracking systems, NASA has had the opportunity to prep its Martian fleet of spacecraft poised and ready to photograph this historic flyby.
Researchers thoroughly reviewed the comet's trajectory and carefully studied any effects the flyby may have on the spacecraft, and determined the risk was minimal. However, several of the orbiters were moved to alternate positions where they would be shielded by the Red Planet from any cometary dust. The Mars Reconnaissance Orbiter (MRO), Mars Odyssey, and MAVEN will all be observing Comet Siding Spring from orbit, while Curiosity and Opportunity will attempt to image the comet from the planet's surface. Both rovers are in the midst of Mars' dusty season, so capturing the comet may be a difficult task. Curiosity will also make use of its ChemCam and try to determine what minerals are contained within the comet.
MRO will be doing exactly what its name says, reconnaissance on the comet's nucleus. It will gather data on the shape, and composition of the nucleus, in order to learn more about the comet's interior. By using its infrared and visible spectra instruments, Odyssey will focus on Siding Spring's tail, hoping to determine if the close encounter with Mars has any lasting effect on the comet. Since MAVEN is designed to study the upper atmosphere, it will be on the lookout for any atmospheric changes due to the comet. In addition, MAVEN will use its ultraviolet spectrometer to capture views of Siding Spring, and possibly even map the comet. Shortly after passing by Mars, Siding Spring will zip past the Kepler Space Telescope. Scientists hope to capture more images of the comet, thus further determining if there was any impact from the flyby.
Want to see the comet as it flies by Mars? Well, if you live in the Southern Hemisphere you just might be able to. So, bust out your binoculars and your telescopes, as this cosmic event will be visible for a couple days. If you are able to capture the flyby, please be sure to send us your photos, and stay tuned for further updates.