Hubble Spots Mars-Bound Comet Sprout Multiple Jets
The images above show - before and after filtering - comet C/2013 A1, also known as Siding Spring, as captured by Wide Field Camera 3 on the NASA/ESA Hubble Space Telescope.
On 19 October the comet will pass within 135 000 kilometres of Mars - less than half the distance between Earth and our Moon.
The image on the left, obtained on 11 March, shows comet Siding Spring, at a distance of 568 million kilometres from Earth. Hubble can't see Siding Spring's icy nucleus because of its diminutive size. The nucleus is surrounded by a glowing dust cloud, or coma, that measures roughly 19 000 kilometres across.
The image on the right shows the comet after image processing techniques were applied to remove the hazy glow of the coma revealing what appear to be two jets of dust coming off the location of the nucleus in opposite directions. This observation should allow astronomers to measure the direction of the nucleus's pole, and axis of rotation.
Hubble also observed Siding Spring on 21 January as Earth was crossing its orbital plane, which is the path the comet takes as it orbits the Sun. This positioning of the two bodies allowed astronomers to determine the speed of the dust coming off the nucleus. This information can be used to determine whether, and to what degree, dust grains in the coma of the comet will impact Mars and spacecraft in the vicinity of Mars.
Discovered in January 2013 by Robert H. McNaught at Siding Spring Observatory, the comet is falling toward the Sun along a roughly 1 million year orbit and is now within the radius of Jupiter's orbit. The comet will make its closest approach to our Sun on 25 October at a distance of 209 million kilometres – well outside of Earth's orbit. The comet is not expected to become bright enough to be seen by the naked eye.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.
(Adapted from the original article published on the NASA website.)