This autumn a remarkable other-worldly happening will take place: Mars will have a close encounter with Comet C/2013 A1 Siding Spring, which approaches the Sun for the first time in its existence, according to information provided by NASA. This event has a special significance for the scientific community, mainly due to the remarcably short distance between the surface of Mars and the comet at its most critical moment. It is expected that in October 19 the comet’s flyby will be at only 82,000 miles, which is less than 10 % the distance experienced by any known Earthly similar cosmic experience.
For NASA, the comet’s passage is a unique opportunity to gather new data regarding a comet’s structure, composition or dynamics, 3 spacecrafts being expected to be involved in this celestial “rendezvous”. The adventure could swing both ways however, the comet’s shedding material posing a great danger to the integrity of orbiters. At cosmic speeds (in this case a 35 miles per second velocity is to be expected) even the tail’s half a millimeter particles could induce significant damage to any spacecraft’s structure. Currently, NASA operates two Mars orbiters, the Mars Reconnaissance Orbiter (MRO), arrived in 2006, and 2001 Mars Odyssey, still active since 2001. The third spacecraft, Mars Atmosphere and Volatile Evolution (MAVEN) is still on its way to Mars, being expected to enter orbit in September.
MAVEN will focus on studying the gases erupting from the nucleus into the comet’s coma and the effect of the passage on planet’s upper atmosphere. Odyssey will have to analyze the spectral and thermal properties of the coma and tail. MRO, similarly to MAVEN, will try to reveal new aspects of the gases present in the coma, as well as monitoring upper atmosphere changes in temperature, cloud formation and electron density. New features regarding the nucleus, like its rotation rate and surface details are expected to complete the data gathering. However, the main priority of this composite mission remains the overall protection of the orbiters.
[ads2]
The teams operating the spacecrafts will focus on keeping them on the opposite side of Mars during the most dangerous moments of the flyby. Anticipating the whole event, each of the orbiters should make re-positioning maneuvers in order to be placed in an ideal spot during the flyby. MRO already made one in July 2 with an additional move planned for August 27. Mars Odyssey is scheduled for a similar relocation in August 5 and MAVEN, after arriving in the vicinity of Mars, will perform a “precautionary maneuver” in October 9.