India's space probe at Mars' doorstep

K. S. Jayaraman

doi:10.1038/nindia.2014.126 Published online 22 September 2014

Closing in on the red planet.

AF archive / Alamy

After the triumphant arrival of NASA's Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft  on Mars today, space scientists across the world are eager to see similar success with the Mars Orbiter Mission (MOM) — also known as Mangalyaan — India's first interplanetary probe.

Designed and developed by the Indian Space Research Organization (ISRO), Mangalyaan was launched into an initial parking orbit around Earth on 5 November, 2013 by ISRO’s Polar Satellite Launch Vehicle (PSLV) rocket. After a series of manoeuvres, it left Earth's orbit in December 2013 and has been racing towards Mars since then. MAVEN launched by NASA on 18 November 2013 entered the Mars orbit today (21 September 2014), while India's MOM is poised to follow suit.

"The MAVEN team sends its best wishes to the MOM team for a successful insertion into Mars orbit and for the science mission that will follow," Bruce Jakosky, MAVEN’s principal investigator from the University of Colorado at Boulder told Nature India.

After completing an interplanetary journey of almost 10 months and 680 million kilometres, MOM is programmed to drop into Mars orbit early morning on 24 September after the crucial Mars Orbit Insertion (MOI) manoeuvre. The manoeuvre will slow down the spacecraft enough to “capture” into Mars orbit.

ISRO Scientists are keeping their fingers crossed for the insertion manoeuvre, the final challenge to the mission. It requires waking up MOM's on-board 440-newton liquid fueled engine that has been "asleep" for almost 10 months.The last time it fired was on 1 December 2013 to "slingshot" the spacecraft from the Earth orbit on a Sun-centric trajectory towards Mars.

Not to take a chance, ISRO scientists will test fire the engine for four seconds this afternoon (22 September, 2014) to judge its readiness for its key role two days later. Should there be a problem with the main engine, ISRO has a contingency plan that involves firing Mangalyaan's eight smaller (22-newton) attitude control thrusters, Koteeswara Rao, ISRO scientific secretary, told Nature India.

The fuel burn for orbit insertion manoeuvre will be performed autonomously (without the need for commanding from Earth) on 24 September 2014 morning and the insertion will take place while MOM is behind Mars and out of radio contact. Proof of a successful orbital insertion will come several minutes later via ground stations operated by ISRO in Byalalu near Bangalore, NASA in Goldstone, California and the European Space Agency in Madrid.

According to ISRO, if the orbit insertion is successful, Mangalyaan will settle  into an elliptical orbit with a period of 76.8 Earth hours. At its closest point, it  will be flying in the upper atmosphere, about 423 km above the Mars surface and at its farthest point, the spacecraft will be about 80000 km above. The orbit will not be the same as planned if the insertion takes place using the smaller thrusters as they have to be fired for longer duration, according to Rao.

During its planned six-month mission in Mars orbit, Mangalyaan's five scientific payloads, will measure methane — a possible clue for life in Mars — in the planet’s atmosphere, map the surface composition and mineralogy, and collect data to help understand why and when Mars lost the liquid water that once flowed there.

"Measurements that MOM will make overlap in interest with the measurements that MAVEN will make," Jakosky said in an email. "There would be real value in either coordinating, making the observations, or in analyzing the data jointly. We've started discussions with the the MOM team about joint analysis." Jakosky said. The two teams can do valuable collaborative science even if they didn’t coordinate the observations, he said.

Recent data from  NASA's Curiosity rover revealed no signs of methane in the near-surface Martian environment. If Mangalyaan detects methane in the upper atmosphere the discovery may justify the $70 million spent on the mission, says an ISRO scientist.ISRO  has said that MOM's  key objective is to demonstrate India's capability to build and launch interplanetary probes and test home-grown navigation and deep space communication technologies. Any science that comes out of this low-cost mission is a bonus, ISRO maintains.

If its mission succeeds,  ISRO says, India will become the first Asian country to send a probe to Mars and become the fourth member of a club that currently includes only Russia, the United States and Europe.