Call it an unfortunate coincidence. Indian scientists are concerned their Mars probe may arrive about the same time a comet blasts past the Red Planet.
There’s worry that the methane in the comet’s tail will give false readings on one of the probe’s instruments used to detect the gas in the Martian atmosphere. Methane, while intimately associated with living things like cows, people and bacteria, can also be produced by chemical reactions between water and rocks.
Comet C/2013 A1 Siding Spring was discovered on January 3 this year by Robert McNaught of Australia. Once an orbit had been calculated, astronomers discovered that the comet would pass only about 93,000 miles (150,000 km) from Mars on October 19, 2014.
The comet itself could be anywhere from a few miles to a few dozen miles across, but the tail and atmosphere it develops from heating by the sun could easily span hundreds of thousands of miles. Comet tails and their fuzzy shrouds called comas are made of dust and vaporized ices of water, methane, ammonia and carbon dioxide.
While the possibility of A1 hitting Mars is remote, the rarefied dust and gases in the comet’s head and tail could brush the planet’s atmosphere as the comet speeds by at some 35 miles (56 km) a second.
Mangalyaan - Hindi of ‘Mars craft’ – is the first interplanetary mission of the Indian Space Research Organization (ISRO). The probe will study the composition of the Martian atmosphere, photograph the surface and map the planet’s minerals from orbit.
With an expected launch on November 27 and 9-month trip time, Mangalyaan will arrive in late August before the comet makes its closest approach.
There’s talk, according to a recent article in the online India Daily News and Analysis, that some ISRO mission planners are considering alternative launch dates to prevent their methane-detector from giving false readings.
While I’m only an amateur astronomer it would seem to me that having the orbiter in place before the comet arrives would be a real boon. It could begin sampling atmospheric gases and then record the affects – if any – that the Siding Spring comet might introduce. In effect, Mangalyan would serve as both Mars AND comet probe. Possibility it could even be re-directed for a time to photograph the comet from a spectacularly close distance.
We’ll wait to see what happens. Astronomers are keeping a close eye on this comet and refining exactly how close a pass it will make to the Red Planet. Stay tuned.