Why India went to Mars



by Gurbir Singh



Bangalore, India (SPX) Sep 23, 2014



MOM has eight small thruster used for attitude control but its main rocket engine is the Liquid Apogee Motor (LAM) was developed by ISRO for its communication satellites.

India went Mars because Japan and China had tried and failed and she wanted the glory to the first Asian country to succeed. The small cars sized Mars Orbiter Mission (MOM) with its modest 15kg science package of five instruments was launched by the Indian Space Research Organisation (ISRO) on 5th November 2013 from India's space port Shriharikota on the east coast and is due to arrive on 24th September.

The Cold War between the Soviet Union and USA gave rise to the Space Race that took men to the Moon has now re-emerged in Asia. Japan, India and China now competes for national prestige and glory in space "firsts" but just like the Space Race of the 1960's each nation denies that a race exists.

Japan has sent space probes to Mars and Venus but in both cases failed to orbit either planet. It has succeeded in an extraordinary technological achievement in sending a spacecraft to an astroid and returning grains of astroid material back to Earth. The largest module on the International Space Station currently in Earth orbit, Kibo was built by the Japanese Space Agency.

Backed by a large and growing economy, guided by a highly focused political strategy that can only be delivered by a single party state, China is the undisputed leader in space in Asia. Today China has a rover on the surface of the moon, a space station in Earth orbit and over a decade-long experience of human spaceflight. No human has set foot on the Moon since 1972. Current consensus has it that the next person to walk on the Moon will be from China.

In 2011, China's mission to Mars, launched aboard a Russian rocket failed to leave Earth orbit. With Japan and China out of the running, India saw an opportunity to get to Mars during the 2013 launch window and grabbed it. In so doing, India was replicating a tactic used during the USA/USSR race to Moon in 1968. Apollo 8, was designed to test the American lunar module in Earth orbit.

The lunar module development fell behind schedule so NASA took the extremely high-risk decision to send Apollo 8 to the Moon instead. It was high risk because no human had ever left Earth orbit before and the manned Apollo spacecraft had only been in space once before.

Despite ISRO's absence of experience in space station, lunar rovers, heavy lift rockets and human spaceflight, it does have extensive experience in designing, building launching and satellites.

There are just over 1100 satellites in Earth orbit today 74 of which were built in India and 58 are in currently in operation. ISRO's heavy lift rocket, GSLV-3 with an indigenous cryogenic engine made a successful launch in January 2014 but it is still a couple of years from regular operational use.

MOM was thus launched using the smaller PSLV launcher which not only limited the size of the science payload to 15kg but also required the six Earth orbits for gravity assist to build up the required speed to reach Mars. MOM was launched on 5th November but left Earth orbit on 1st December.

The final hurdle

Travelling at over 22km every second, India's MOM is due to arrive at Mars on 24th September. It has to slow down to get in to orbit. Like a golfer with excellent aim but hitting the ball with excessive power sees the ball passes over the hole. If MOM cannot slow down it will fly past Mars and end up orbiting the Sun.

MOM has eight small thruster used for attitude control but its main rocket engine is the Liquid Apogee Motor (LAM) was developed by ISRO for its communication satellites.

LAM has a long and reliable track record in ISRO's satellite program and it was used by ISRO for its 2008 mission to the Moon, Chandrayaan-1. But the ten month journey to Mars is an untested long interval between two consecutive firings of the LAM engine. This is the one final step that has to work for ISRO to claim its prize as the first Asian nation to arrive at Mars.

ISRO has uploaded the the commands MOM will execute for the Mars Orbit Insertion (MOI) as it approaches Mars. If all goes to plan MOM will point to the opposite direction of travel and at 01:47 UT on Wednesday 24th September will ignite the LAM for 24 minutes and 14 seconds to reduce speed from over 5.1km per second to just over 4.3km per second relative to Mars.

This manoeuvre will use up 250kg of propellent leaving 50km for operational use in its 423km by 80,000km elliptical orbit eventually orbiting Mars once every three days. Most of the 24 minutes during which the LAM engine fires will MOM will find itself in darkness for the first time since it left Earth orbit. The onboard batteries will provide the electric power but the sharp decrease in temperature will occur at a critical time.

Plan B

The 300 day long interval between firing the LAM engine has been ISRO's main concern. Will the engine fire after such a long time? ISRO has gained some confidence by mirroring the LAM firings with an identical LAM engine on Earth. So far so good.

On 24th September, when ISRO's engineers had built in four Trajectory Control Manoeuvres (TCM) on 11th December, 11th June, August and 14th September) during MOM's ten month journey from Earth to Mars. These are small course tweaks to ensure the spacecraft is on the correct course using the eight small thrusters.

The one scheduled for the 14th September was replaced with a successful firing of the LAM for almost 4 seconds on 22nd September to perform the TCM instead of the eight smaller thrusters. Had the LAM failed, ISRO engineers would have had over 24 hours to reconfigure the smaller engines to fire for a longer period to slow MOM sufficiently for it to enter Mars orbit.

In plan B the resulting orbit would not be achieved to a required precision impacting the quantity and quality of the science MOM could undertake. But MOM will be in orbit and ISRO will be able declare a mission success.

Low cost launch

The relative orbits of Earth and Mars result in an optimal launch window for a space craft travelling from Earth to Mars. They occur once every 26 months. In addition to MOM, the 2013 launch windows was used by NASA to launch its Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft which will arrive at Mars two days before MOM.

At around $72 USD, India's MOM is about 10% the cost of NASA's MAVEN. There are significant differences between the two missions that prevent a like-for-like comparison. One of the reasons for this vast price tag difference is simply the nature of the two national economies. Indian space engineers are get paid a lower salary, live smaller homes and drive cheaper cars than their American counterparts.

Another reason for the differences in cost is the amount of re-use of existing infrastructure. ISRO used smaller PSLV launcher and the MOM spacecraft infrastructure modelled on Chandrayaan-1 which itself was based on the Indian National Satellite and Indian Remote Sensing (INSAT and IRS) systems.

Science Objectives

ISRO's first mission beyond Earth Chandrayaan-1 carried science instruments from several countries. MOM has five, all of which were developed in India by ISRO engineers. This was one of the many consequences of developing this mission in breakneck speed.

MOM is more a technology demonstrator than a science mission like NASA's MAVEN. MOM's package of five science instruments includes two cameras (a thermal camera and a optical colour camera) along with a Methane sensor are likely to generate the most interest. Methane has been detected on Mars since 2003 at varying times from Earth based observatories, spacecraft in martian orbit and spacecraft on the surface.

It is highly unlikely that MOM will make any groundbreaking scientific discoveries that have escaped the American and European missions that have been scrutinising Mars with higher specification instruments for decades. But it is possible. A detection of methane by the methane sensor along with an associated surface feature imaged by the colour camera could help identify locations of the surface of Mars for further study.

MOM is ISRO's first mission to Mars, getting it in to orbit is going to be the key objective. Potential science at a that it can collect will be a bonus. Getting to Mars is not a trivial achievement. One of MOM's first actions once in orbit is to take an image of Mars using the colour camera. If the mission can get to this point, ISRO can legitimately declare success.

Two months after winning India's general election, India's new Prime Minister Modi was present in the mission control centre of Shriharikota to watch live the launch of the PSLV C25 delivering for foreign satellites to Earth orbit. With an eye on enhancing greater regional influence within the eight countries of the South Asian Association for Regional Cooperation (SAARC) , he made a surprising announcement.

During his post launch speech in english commending ISRO's success he directed "our Space community, to take up the challenge, of developing a SAARC Satellite - that we can dedicated to our neighbourhood, as a gift from India.

A satellite, that provides a full range of applications and services, to all our neighbours. I also ask you, to enlarge the footprint of our satellite-based navigation system, to cover all of South Asia". India's reason for going to Mars is the same as that of other nations. India is now turning to its prowess in space as an instrument for regional diplomacy and foreign policy.

Gurbir Singh is the publisher of www.astrotalkuk.org and author of the book Yuri Gagarin in London and Manchester.