Updated: September 21, 2014 11:51:07 am
Over the last few days, a hotline connecting scientists at the mission operations room at the Indian Space Research Organisation’s Telemetry, Tracking and Command centre in Bangalore with scientists from NASA’s Jet Propulsion Laboratory (JPL) in Goldstone, California, and Canberra, Australia (where NASA operates Deep Space Networks), has been buzzing constantly.
A spacecraft launched by ISRO on November 5, 2013, and another launched by NASA on November 18, 2013, are set to enter the orbit of planet Mars within 48 hours of each other. With nine of 51 past attempts to get to the Red Planet failing at the point of entry into the orbit of Mars, the last thing scientists at ISRO and NASA want is for their spacecraft to collide. With D-Day fast approaching for both missions — September 22 for NASA’s Maven spacecraft and September 24 for ISRO’s Mars Orbiter — scientists from both the space agencies are trying to ensure that everything goes smoothly at both ends.
The smallest of errors — in calculation of location, distance and the precise moment when a spacecraft must insert itself into the orbit of Mars — can result in losses worth millions of dollars. But ISRO is counting its gains too: the Orbiter cost it only $71 million, a fraction of what it took for Maven ($671 million) or for the Hollywood space blockbuster Gravity ($100 million).
While NASA has 21 Mars expeditions to its credit — with 15 successful ones, including the first winning fly-by in July 1965, the first successful orbit mission in October 1972 and the first successful Mars landing with Viking 2 in 1980 — the Mars mission is the farthest the Indian space programme has gone.
Though ISRO will be solely responsible for manoeuvring its spacecraft into the orbit of the Red Planet on the morning of September 24, the space agency will be leaning significantly on NASA’s Deep Space Network to communicate with the Mars Orbiter.
At 7.30 am on September 24, exactly 48 hours after they navigate the entry of the Maven into the Mars orbit, 250 technicians from NASA’s JPL in California and Canberra will throw their weight and the might of four 71-metre antennas behind ISRO’s mission operations centre (MOX for short) to communicate with the Mars Orbiter. At that moment, the Orbiter will be about 224 million km away from Earth.
For ISRO scientists venturing into deep space for the first time, NASA is also a point of reference for all the number crunching that has been done to determine the precise distances, moments and speeds at which the Mars Orbiter will have to manoeuvre in order to end up in an orbit where its nearest distance from the Red Planet is 423 km.
“Any country in the world that wants to undertake deep space missions has to go to NASA’s JPL for ground station support. We have a dedicated hotline where if I pick up the phone here, somebody from JPL will pick up at the other end,” says Mars Orbiter Mission project director S Arunan.
“If you look at some of the missions that failed at the insertion stage, it was because they failed to estimate the distance from Mars. This occurred in the early phase of space history. A lot of learning has since occurred in tracking and determining orbits. We have cross-checked our data with numbers determined by NASA’s JPL and both numbers match exactly,” says ISRO scientific secretary V Koteswara Rao.
In the period since the erstwhile Soviet Union made the first attempt to travel through deep space to get to the Red Planet in October 1960, 51 Mars missions have been attempted, including 22 to put a spacecraft in orbit around Mars, but only nine have been successful. Of these, 10 attempts were made since the 1990s and only four have been successful — three from NASA and one from the European Space Agency. Two NASA missions, one ESA, one Japanese, one Russian and one Chinese mission have all failed. If ISRO’s Orbiter succeeds, India will be the first among global space-faring nations to get to Mars in the first attempt.
At ISRO’s Mission Operations Centre in Bangalore, a group of around 100 scientists has been working continuously, ensuring that the Orbiter has stayed on its 666-million-km heliocentric course to the Red Planet since its launch. Over the last 300 days, the ground station at Byalalu has been monitoring the Orbiter between 11 am and 11 pm. During the next 12 hours, it is monitored by ground stations in the US, Australia and Spain while scientists at the Byalalu centre monitor data transmitted by these deep space networks.
A liquid apogee motor (LAM engine), the primary engine in the spacecraft, had fired for 21 minutes on December 1 to send the Orbiter on its way to Mars. On September 24, it is this engine that will take centrestage. After lying dormant for the past 300 days, the engine will have to fire into action for a precise 24.23 minutes to provide a deceleration force of 1.1 km/sec to enable the Orbiter to synchronise into the orbit of Mars.
“When we reach Mars, our spacecraft will have a velocity of 22.57 km/sec whereas Mars’ velocity is 25.71 km/sec so our spacecraft is slow. But when it is coming under the influence of Mars, it gains a velocity of 5.7 km/sec but we don’t want that much velocity. What we require is 4.6 km/sec. So from 5.7 km/sec, I have to reduce this velocity to 4.6 km/sec so the deceleration needed is 1.1 km/sec. This is to be achieved by firing the engine,” says V Kesava Raju, post-launch director of the Mars Orbiter Mission.
With days left for the key manoeuvre, here at the mission operations centre, proof and prayers are sought in equal measure. “Most of us working at MOX cannot sleep until the mission is done well. There is anxiety over the data every day but things have gone well so far,” says a scientist who does not want to be identified.
Much of the tension is around whether the LAM engine will fire after lying dormant for so long. In case of a failure, Plan B will be executed where eight small engines called AOC thrusters will be fired. ISRO, however, needs the LAM engine to fire to get to the desired distance of 423 km from Mars and its failure will result in the mission being forced to observe Mars from further out.
On September 22, ISRO will conduct a small four-second test of the LAM engine to slow the spacecraft by 2.14 metres per second and if the engine fails to fire in the test, ISRO will be forced to switch to its Plan B on September 24, says Rao.
With the Mars Orbiter being an intelligent, self-contained and autonomous system, it has to assess situations and take decisions on its own on the basis of the commands that scientists at the mission operations centre have uploaded to the spacecraft in recent weeks.
“Because of the time delay in communication (12.5 minutes for one-way radio communication on September 24), all operation commands are uploaded and stored on board the spacecraft for execution at the appropriate time. In normal conditions, we will not give any command on September 24,” says Rao, the ISRO scientific secretary.
“In case of any untoward event, the spacecraft has to survive on its own. If the attitude is not proper, then communication with Earth may be a problem. The spacecraft will have to correct the attitude on its own and get into a position where it can communicate with the Earth,” says Raju, the post-launch director.
ISRO has consistently said that though the mission is a scientific one, the main objective is to demonstrate the capability of reaching the Mars orbit. “I would say 85 per cent of our mission is for technology demonstration that we can orbit Mars,” says ISRO chairman
Radhakrishnan, currently on an extended term and set to retire at the end of the year, is looking for a final hurrah. After a series of failures and controversies in his early days as chairman, Radhakrishnan has overseen some key successes in India’s space programme in recent days, including the successful firing of an indigenous GSLV rocket. “The trans-Martian injection of December 1, 2013, and the Martian insertion of September 24, 2014, are the two crucial parts of the mission,” says Radhakrishnan, who is also a Kathakali enthusiast.
Designated an outstanding scientist, the former director of ISRO’s Laboratory for Electro Optic Systems and Project Director for the Astrosat satellite is the key go-to man for different units involved in the Mars Mission. “During Earth-bound manoeuvres and during the heliocentric phase, we have tested the systems several times and everything was found to be normal,” he says.
The mission director for ISRO’s 2008 moon mission Chandrayaan 1 and the director for its proposed Chandrayaan 2 is overseeing the Mars mission as well. He is currently the programme director for Indian Remote Sensing and Small Satellites Programme. As Annadurai says, the success of the Mars mission is crucial for ISRO to propose funding for new projects.
For the senior scientist with the ISRO satellite centre in Bangalore, the Mars mission is his maiden venture as project director. His team created the Mars Orbiter for ISRO in 12 months. Since the launch, Arunan said, he and his team have been in touch with NASA’s Jet Propulsion Laboratory as well as ground stations in Bangalore, Madrid, California and Canberra.
Raju and his team have been responsible for monitoring the Mars mission through its journey. He has been involved in building multiple satellites for ISRO and was earlier a mission director for ISRO’s Cartosat project. “We are confident the spacecraft will complete its intended life span of six months as a good thermal environment has been provided,” he says.
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