Scientists excited about the visual treat despite safety risk

The Indian Mars Orbiter Mission (MOM) spacecraft, two weeks old in its Martian orbit, is getting primed to glimpse a unique cosmic event.

A little past midnight on October 20, MOM — millions of kilometres from its earthly home — will be privy to an astronomically significant fly-past of Comet Siding Spring. MOM will duck for cover behind Mars, like the NASA missions there; and if lucky, it may capture and send snapshots of those moments to us.

Comet watchers say Siding Spring is passing through the Solar System for the first time and that it will approach Mars at a tenth of the distance any comet has visited Earth.

For MOM, as well as the handful of NASA missions exploring Mars, the comet’s fly-by is both a spectacle and a hazard. As it departs, Siding Spring’s large dust trail can potentially wreak havoc on the sensitive electronic devices of earthly spacecraft and disable them.

ISRO engineers handling MOM from the command centre at Bangalore have been trying to balance MOM’s safety with the visual treat the fly-by promises, according to MOM Mission director V. Kesava Raju. For the October 20 encounter, the 25-plus team of engineers associated with the five MOM instruments were working out the best position for the instruments, he added.

Opportunities to take pictures of the comet and its tail during October 19 – 21 are also under discussion. Post-encounter, the key concern would be to protect MOM’s body from exposure to the large cloud of dust.

“The comet will make its closest encounter with Mars around 1.40 a.m. IST on October 20 give or take 15 minutes [which will be 20.08 hours UTC on October 19]. We have already taken steps to ensure that the spacecraft will be shielded behind Mars at that time,” Dr. Raju told The Hindu.

On October 6, the orbit of the spacecraft was shortened to 72,200 km (from about 78,000 km) at the long end while keeping the near end from Mars intact at 423 km.

MOM’s Twitter handle @MarsOrbiter recently posted: “Joining the welcome party for comet #SidingSpring. @MarsCuriosity, @MAVEN2Mars, @HiRISE, #MarsOdyssey & #MarsExpress are there too. Excited!”