Comet Siding Spring and Mars

Comet Siding Spring


Discovery of Comet Siding Spring (C/2013 A1)

A comet was discovered by Robert McNaught on January 3, 2013 with a 20" (0.5 m) Schimdt telescope at the Siding Spring Observatory. At the time of discovery, the comet was beyond the orbit of Jupiter.


Like other comets discovered using equipment at the Siding Spring Observatory, this comet informally became known as Comet Siding Spring. Its official designation was C/2013 A1. As the comet's naming convention indicates, C/2013 A1 was the first long period comet discovered in 2013. The Siding Spring Observatory is in New South Wales, Australia. It's located 3,822 feet (1,165 m) above sea level on the side of Siding Spring Mountain. There is more than $100,000,000 of research equipment at the observatory, including twelve telescopes.


The Catalina Sky Survey (CSS) captured images of C/2013 A1 on December 8, 2012, but its images were not identified as a comet. This recent phenomena, where a comet can be imaged prior to its official discovery is called a "precovery".








The Size of Comet Siding Spring

How big is comet Siding Spring? Like all comets it is not a perfect sphere. Estimates for the diameter of the nucleus, at its wide point, have been between 0.62 and 31 miles (1 to 50 km). That's a fairly wide range obviously. It's difficult to tell, since the coma is already thousands of miles wide. As the comet nears Mars, the size of Comet Siding Spring's nucleus will be more accurately determined.



Orbit of Comet Siding Spring

The orbit of Comet Siding Spring (C/2013 A1) is highly eccentric. It spends the vast majority of its life in the Oort Cloud.


Its orbital path can be seen in the movie below. The most interesting thing about C/2013 A1's orbit is that it will come very close to Mars on October 19, 2014. If it were to hit Mars, the explosion would release hundreds of millions or billions of megatons of energy. For reference, the atomic bomb dropped on Nagasaki, Japan at the end of World War II was 0.023 megatons and the 1908 airburst over the Tunguska River in Siberia was 4.0 megatons.



Will Comet Siding Spring hit Mars?

Four simultaneous points of view of Comet Siding Spring's orbit (C/2013 A1). Click on icon in lower right corner to enter full screen HD mode.

Credit: Osamu Ajiki. Modified by Ron Baalke (JPL). Adapted by Kevin Curran.

Astronomer Leonid Elenin observed Comet Siding Spring on February 27, 2013. Based on his observations, astrophysicists initially determined that Comet Siding Spring would pass 0.000276 AU (41,300 km, 25,700 mi) from the surface of Mars on October 19, 2014. For reference, the average distance between the Earth and Moon is 238,900 miles (384,400 km).


In the early days of observation, a JPL astrophysicist stated, "Since the impact probability is currently less than one in 600, future observations are expected to provide data that will completely rule out a Mars impact." On April 15, 2013, when the rest of us were paying taxes, JPL released its updated calculations stating there is only a 1 in 120,000 chance that Comet Siding Spring will hit Mars on October 19, 2014.


After 493 days of observation, Its closest approach to Mars was revised to 0.000887 AU (82,460 miles, 133,700 km).

If the comet did hit Mars, the effect on our neighbor would be monumental and would mark the second time in recorded history that a comet has been observed hitting a planet. The first, and only recorded observation, was the impact of Comet Shoemaker-Levy 9 on Jupiter in 1994. However, the book Fall of a Thousand Suns: How Near Misses and Comet Impacts affected the Religious Beliefs of our Ancestors sheds light on some of the stunning impacts and near misses that our ancestors experienced.




Meteor showers on Mars from Comet Siding Spring

So will Comet Siding Spring cause a meteor shower on Mars? Possibly.


At best, the dust will miss the red planet by 69,800 km (Ye and Hui, 2014). At worst, using extremes in mathematical uncertainty, it will engulf the Mars in a meteor storm (Ye and Hui, 2014). It might also engulf the Martian Moon Deimos, which will be two Martian radaii closer to the nucleus of Comet Siding Spring (Ye and Hui, 2014).


Although meteor showers have only been observed on both Earth and Mars (Spirit Rover, 2004), meteor showers are assumed to occur on several planets and moons in our solar system.




Will Comet Siding Spring damage Mars orbiters?

Mars Reconnaissance Orbiter

Artist conception of NASA's Mars Reconnaissance Orbiter passing above Mars.

Credit: NASA / JPL

After Comet Siding Spring (C/2013 A1) has passed closest to Mars, it could take 30-60 minutes for meteors to reach the orbiters (Ye and Hui, 2014). In March of 2014, Soren Madsen, the Mars Exploration Program's chief engineer, said that JPL was looking at ways to allow the four operational NASA orbiters (Mars Reconnaissance Orbiter, Mars Express, and Mars Odyssey) to make observations of the comet and then duck for cover behind the far side of the planet before the meteor storm. "We're basically hiding the orbiters behind Mars."


Mars Exploration Program chief scientist at NASA's Jet Propulsion Laboratory, Rich Zurek, had this to say, "Our plans for using spacecraft [orbiting] Mars to observe Comet Siding Spring will be coordinated with plans for how the orbiters will duck and cover, if we need to do that."


Approximately three weeks before Comet Siding Spring's closest approach to Mars, two more orbiters will arrive. NASA's Mars Atmosphere and Volatile Evolution (MAVEN) and the Indian Space Research Organisation's (ISRO) Mars Orbiter Mission (MOM or Mangalyaan). MOM's mission is to study and develop the designs, techology and planning required for an interplanetary mission. If successful, ISRO would be the fourth space agency to reach Mars joining NASA, the European Space Agency and Soviet Space Program.




Will Comet Siding Spring damage Mars rovers?

Mars Rover

Artist conception of Mars Rover, Curiosity.

Credit: NASA / JPL

Currently, only NASA has functioning rovers on the Martian surface.


Due to the Martian atmosphere, the two operational U.S. rovers on Mars (Opportunity and Curiosity) are in less danger from Comet Siding Spring (C/2013 A1). Most of the dust-sized debris shed by the nucleus of Comet Siding Spring will burn up in the Martian atmosphere. However, larger pieces of debris could impair or destroy our rovers. Additionally, Opportunity is powered by the Sun, so it would need to use its reserve power in the extremely unlikely event that a larger impact kicks dust in the Martian atmosphere. Curiosity does not have the same problem. It is nuclear powered.


If NASA can correctly assess the danger, then our orbiters, rovers, and telescopes may be able to send back not only some of the most stunning images of comets in 2014, but in history.







Where and when can you see Comet Siding Spring?

Comet Siding Spring will be visible with small telescopes, and even binoculars, in the Southern Hemisphere beginning in the middle of September in 2014. It will be in the constellation Ophiuchus.


Five U.S. spacecraft orbiting Mars may be able to capture images of the passing comet. Mission planners will have to determine if the orbiters can be reprogrammed to observe the comet. For example, the Mars Reconnaissance Orbiter (MRO) is programmed to point down at the planet not up.


The comet's closest approach to Earth will be on October 25, 2014, when it will be 130 million miles (209 million km) distant. It is expected that Comet Siding Spring will be too faint to be seen with the naked eye.




Image - Comet Siding Spring from NEOWISE (January 14, 2014)

Comet Siding Spring - NEOWISE
NASA's NEOWISE mission captured images of C/2013 A1 on January 14, 2014.


From December 2009 to February 2011, the Wide-field Infrared Survey Explorer (WISE) surveyed the entire sky from Earth orbit. It was reactivated in September of 2013, in order to help discover and study asteroids and comets. It was renamed NEOWISE.


Its first discovery was on December 29, 2013, when it found a near-Earth asteroid named 2013 YP139. On January 14, 2014 it captured one of the first images of Comet C/2013 A1, better known as Comet Siding Spring.














Images - Comet Siding Spring seen from Hubble (October 29, 2013 - March 11, 2014)

The Hubble Space Telescope took the final image (seen below) on March 11, 2014 when Comet Siding Spring was 353 million miles (568 million kilometers) away from Earth. The coma was 12,000 miles-wide. Two jets, first observed on October 29, 2013, still spewed material from the coma. These jets will allow astrophysicists to determine the rotation of Comet Siding Spring.


Comet Siding Spring seen from Hubble (January - March 2014)

Enhanced images of Comet Siding Spring (C/2013 A1):

Image on left taken on October 29, 2013. Comet's distance from Earth was 605 million km.

Image in center taken on January 21, 2104. Comet's distance from Earth was 552 million km.

Image on right taken on March 11, 2014. Comet's distance from Earth was 568 million km.

The images showed that there were two jets of material spewing from the nucleus.

Credit: NASA (Hubble Space Telescope's Wide Field Camera 3)




Speed of Comet Siding Spring

How fast will Comet Siding be traveling? Its speed varies, but during its closest approach to Mars the Jet Propulsion Laboratory estimates that Comet Siding Spring will be traveling 35 miles (56 km) per second. Speeds like that are almost impossible to process, so let's break it down a little.  It's 2,100 miles (3,360 km) a minute, which means Comet Siding Spring (C/2013 A1) could travel from Chicago to Los Angeles in 50 seconds.


Be thankful it's Mars in the crosshairs, in 2014, and not Earth.




Comet Siding Spring's orbital period

The orbital period of Comet Siding Spring (C/2013 A1) has yet to be determined. It's perihelion will occur on October 25, 2014. This may be the first, and last, time Comet Siding Spring has ever entered the inner solar system. If it does return, it will not do so for a million years.




When will Comet Siding Spring return? (Next Perihelion)

Due to its orbit not being definitively predicted, the next return of Comet Siding Spring to the inner solar system has yet to be determined. Don't worry about it. Even if you eat right and exercise, you won't be alive to see its return unless you're the villain from the movie Out of Time.