14 DAY TRIAL // Astronomers using the NASA/ESA Hubble Space Telescope were recently able to collect a new image of comet C/2013 A1, which is currently heading towards a flyby of Mars. The object is scheduled to reach its point of closest approach to the Red Planet on October 19, when it will pass some 135,200 kilometers (84,000 miles) above its surface.
According to scientists at NASA, this is the equivalent of half the distance between the Earth and the Moon. Astronomers will be observing the event with a number of space- and ground-based telescopes, hoping to catch all of its elements in detail. The image released on Thursday, March 27, is part of the efforts to prepare for this event.
The comet, also known as Siding Spring, was discovered by Siding Spring Observatory astronomer Robert H. McNaught, on January 3, 2013. The object is believed to have originated in the Oort Cloud, a collection of frozen objects located towards the outskirts of our solar system, beyond the Kuiper Belt.
McNaught used the 50-centimeter (20-inch) Uppsala Southern Schmidt Telescope to discover the comet, which at the time was located in the constellation Lepus, around 7.2 astronomical units (AU) away. An AU is the mean distance between Earth and the Sun, around 157 million kilometers (93 million miles). By comparison, Saturn is located 9.5 AU away from the Sun.
Astronomers believe that it may have taken the comet several million years to travel the huge distances separating the Oort Cloud from the Sun. On October 19, the object will pass extremely close to the Red Planet, so much so that its coma may actually envelop the entire planet. The point of closest approach will be reached at 18:30 UTC.
In anticipation of this event, Hubble captured this image of C/2013 A1 on March 11, when the comet was around 569 million kilometers (353 million miles) away. Though its core is too small to distinguish even with this telescope, the coma trailing the comet is plainly visible, as it spans around 19,300 kilometers (12,000 miles).
The processed image on the right reveals what appear to be two different jets coming out of the cometary core. These jets are heading in different directions, astronomers say, making it easier for instruments to measure the orientation of the object's poles and to figure out its rotation axis.
“This is critical information that we need 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,” explains astronomer Jian-Yang Li, who is based at the Planetary Science Institute in Tucson, Arizona.
Currently, there are three spacecraft orbiting the Red Planet – NASA's Mars Reconnaissance Orbiter and Mars Odyssey, and the European Space Agency's (ESA) Mars Express. On the surface, the American space agency operates the Mars Science Laboratory (MSL) rover Curiosity and the Mars Exploration Rover (MER) Opportunity.