NASA Mars probes watch comet near-miss
After a dramatic, one-in-a-million-years close encounter between Mars and comet Siding Spring on Sunday, all five functioning US Mars probes survived and are reportedly healthy. NASA confirms that the Mars Odyssey, Mars Reconnaissance Orbiter (MRO), and the Mars Atmosphere and Volatile Evolution (MAVEN) orbiter, along with the rovers Curiosity and Opportunity came through without a scratch and are returning valuable data on the comet.
According to NASA, C/2013 A1 Siding Spring is a newcomer to the inner Solar System as it makes its first ever visit from the Oort Cloud that lies on the outer fringes of the system. Discovered in 2013 by Australia’s Siding Spring Observatory, its trajectory was calculated to take it so close to Mars this year that astronomers at one time feared that it might impact the Red Planet. However, as it drew closer, more precise observations showed that it would only come within a cosmic hair’s breadth.
On October 19 at 11:27 am PDT, Siding Spring reached its closest point to Mars, passing within a mere 87,000 mi (139,500 km) of the planet. For comparison, that distance is about a third of the distance between the Earth and the Moon. NASA’s orbiting probes were in no danger of colliding with the comet, but with it traveling at a speed of approximately 125,000 mph (56 km/sec), the dust from its tail that reached Mars 100 minutes after the encounter posed a threat like a blast of shrapnel. To avoid this, NASA ordered the probes to carry out an orbital maneuver that placed Mars between them and the comet during the danger period.
NASA reports that during the encounter all but one orbiter maintained communications, and all were able to carry out observations that may provide scientists with a unique glimpse into what the Solar System was like four billion years ago.
Mars Reconnaissance OrbiterThe workhorse NASA’s trio of orbiters, the
The space agency says that the MRO watched the comet go by with its High Resolution Imaging Science Experiment (HiRISE), the Compact Imaging Spectrometer for Mars (CRISM), and the Context Camera (CTX), and will continue to observe the comet while it remains within range over the next few days.
Meanwhile, the MRO’s Mars Climate Sounder (MCS), the Mars Color Imager (MARCI) and the Mars Shallow Radar (SHARAD) will record the effects of the comet’s dust tail on the atmosphere.
MAVENNASA's newest orbiter at Mars,
MAVEN’s instruments sent back data on the gases and dust released by Siding Spring, while others are currently assessing the impact of the comet’s tail on the Martian atmosphere.
Mars OdysseyThe longest-lived unmanned probe ever sent to the Red Planet,
The data from these instruments will be downloaded and processed at mission control over the next few days.
Curiosity and OpportunityMeanwhile, NASA’s two surface rovers,
The video below outlines the role of the various probes during the Mars/Siding Spring encounter.