Comet ISON (C/2012 S1) had been lauded as the comet of the century by many astronomers, with the celestial body set to make its spectacular appearance within our skies in the coming months. Unfortunately, if NASA’s recent findings are anything to go by, the entire affair could be a big disappointment. Alas, the space agency have described their latest ISON observations, from the Mars Reconnaissance Orbiter (MRO), as “not very pleasing.”
The Mars Reconnaissance Orbiter and HiRISE
Despite the latest government shutdown, all of NASA’s spacecraft are functioning as normal. In recent days, the Mars Reconnaissance Orbiter, Opportunity and Curiosity have all successfully collected imagery.
The Mars Reconnaissance Orbiter was launched from Cape Canaveral, Aug. 12 2005, and was originally designed as a multipurpose spacecraft to explore the possibility that Mars was home to water. MRO is fitted with a host of instruments to facilitate investigation of the Red Planet’s surface, as well as its atmospheric constituents, boasting a total of six different technologies.
The spacecraft is fitted with a weather camera, a spectrometer, a shallow radar and a Mars climate sounder. In addition to this, MRO also boasts a High Resolution Imagining Science Experiment (HiRISE) camera. Operating in visible wavelengths, the HiRISE device is capable of identifying tiny structures within the unmapped gullies of Mars, and has provided immense detail on many of the geologic structures of the planet.
The Mars Reconnaissance Orbiter’s HiRISE camera was wielded on Sept. 29 to observe comet ISON, as it tore past Mars, heading towards the inner solar system. According to researchers Alan Delamere ad Alfred McEwen, who posted an article on the University of Arizona’s website, HiRISE is said to have observed a small spot of brightness:
“HiRISE saw a small spot at the position of ISON that is relatively bright, like a star, but moving relative to actual stars.”
ISON no Longer Comet of the Century?
The researchers go on to describe the faintness of the comet’s coma – the central atmosphere, surrounding the nucleus of the comet, resulting from solar radiation and winds vaporizing the volatile materials within the comet.
The images collected represent a 256 x 256 pixel area of HiRISE’s view, taken at a distance of eight million miles. The post states that two further observations were being planned for Oct. 1 and Oct. 2. It was estimated, at this point, the comet would have been at its closest approach to Mars – a mere seven million miles.
Sadly, it appears that comet ISON won’t live up to its highly publicized expectations. Discovered by a pair of Russian astronomers (Vitali Nevski and Artyom Novichonok) in September of last year, many had theorized it to be the “comet of the century.”
Based upon the observations of HiRISE, preliminary data suggests that the comet’s brightness is much lower than anticipated. ISON is now under 250 million kilometers from our Sun; as it edges ever-closer to Perihelion, its brightness will continue to amplify as dust and water ice is vaporized by the intense heat.
ISON is a sungrazing comet, and is expected to approach Perihelion (it’s closest elliptical orbit of the Sun) in late November. Astronomical observations suggest, based upon ISON’s hyperbolic path, this is a new comet, derived from the clusters of icy planetesimals within the Oort cloud.
As the comet approaches the Sun, however, the extreme tidal forces are likely to cause it to fragment. Whilst larger comets have been known to survive the perilous journey through Perihelion, smaller bodies are usually not so lucky.
BRRISON Balloon Launch
NASA also planned to launch its Balloon Rapid Response for ISON (BRRISON) mission. The launch was initiated on Sept. 28 to investigate the comet’s constituents, and gain an enhanced understanding of the chemical processes that led to the evolution of complex organic molecules.
Alas, according to a press release put onto the BRRISON website, the payload “… suffered an anomaly following launch…” Consequently, the team were unable to collect any useful data.
According to NBC News, the balloon’s telescope encountered a mechanical glitch just two and a half hours after deployment. The telescope, which had been affixed to the gondola, “returned to a stowed position too rapidly,” pushing it past an internal latch; as a result the telescope remained stuck, and no imagery could be taken.
Although comet ISON no longer appears to be the comet of the century, we await further details from NASA on some of the Mars Reconnaissance Orbiter’s latest observations.
By: James Fenner
BRRISON Website Link