India has become the fourth nation, or group of nations, after the United States, Russia, and the member states of the European Space Agency (ESA), to inject a home-grown spacecraft into orbit around Mars. Earlier today (Wednesday, 24 September), the Indian Space Research Organisation (ISRO) joyfully announced success as its Mars Orbiter Mission (MOM)—also known as “Mangalyaan” (Hindi for “Mars Craft”)—completed a 24-minute “burn” of its Liquid Apogee Motor (LAM) and eight attitude-control thrusters at 7:41:46 a.m. IST Wednesday (10:11:46 p.m. EDT Tuesday), to allow itself to be captured into an elliptical path around the Red Planet, whose closest point (periapsis) is 262 miles (421.7 km) and farthest point (apoapsis) is 47,841.6 miles (76,993.6 km).
Within a short period after the success, ISRO reported to an anxious world that India’s long-nurtured dream of reaching and exploring Mars in its own right had begun. Present at ISRO’s Telemetry, Tracking, and Command Network (ISTRAC) in Bangalore were India’s Prime Minister, Mr. Narendra Modi, together with numerous senior ministers and dignitaries. NASA, which provided tracking support for the MOM/Mangalyaan mission through its Deep Space Network (DSN) of antennas in Goldstone, Calif., Madrid, Spain, and Canberra, New South Wales, Australia, praised India’s achievement. “We congratulate the Indian Space Research Organisation,” said Administrator Charlie Bolden. “It was an impressive engineering feat and we welcome India to the family of nations studying another facet of the Red Planet. We look forward to MOM adding to the knowledge the international community is gathering with the other spacecraft at Mars.”
The arrival of MOM/Mangalyaan comes just two days after Sunday’s triumphant arrival of NASA’s Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft in orbit around the Red Planet. Since its launch atop India’s Polar Satellite Launch Vehicle (PSLV) from the Satish Dhawan Space Centre, on the barrier island of Sriharikota, within the southern state of Andhra Pradesh, last 5 November, MOM/Mangalyaan has followed a “heliocentric” trajectory to reach Mars. The relatively limited propulsive yield of the PSLV and its own LAM engine made it infeasible to inject it directly onto a trans-Mars trajectory, in the same manner as MAVEN. Instead, it was inserted very precisely into a highly elliptical Earth orbit of about 155 x 14,600 miles (250 x 23,500 km) by the PSLV. It was then tasked with executing six LAM “burns,” over a three-week period, to steadily expand its apogee to a maximum distance of 119,846 miles (192,874 km) from Earth, whereupon it would escape the Home Planet’s sphere of influence and establish itself onto a hyperbolic trajectory to rendezvous with Mars about 10 months later.
Following its launch, MOM/Mangalyaan was placed into an orbit which very closely paralleled pre-flight predictions, inclined 19.27 degrees to the equator and with a period of a little less than seven hours. After separation from the final stage of the PSLV, its main antenna and electricity-generating solar arrays were deployed, and the first orbit-raising burn of the LAM took place on 7 November. It lasted 416 seconds and lifted MOM/Mangalyaan’s apogee to 17,550 miles (28,852 km). Subsequent burns further expanded this apogee, firstly to 24,970 miles (40,186 km) on 8 November, then to 44,500 miles (71,636 km) on 9 November and later—after minor technical difficulties—to 73,720 miles (118,642 km) by 12 November. The next LAM firing on 16 November pushed the spacecraft yet further to 119,846 miles (192,874 km), and the final boost on 1 December enabled it to leave Earth’s gravitational influence and set sail for Mars.
Tracked by the Spacecraft Control Centre at ISRO Telemetry, Tracking, and Command Network (ISTRAC) in Peenya, Bangalore, and supported by the Indian Deep Space Network (IDSN) at Byalalu, MOM/Mangalyaan utilized its 22-Newton thrusters to execute the first of four planned Trajectory Correction Maneuvers (TCM-1) on 11 December, by which time the spacecraft was 1.8 million miles (2.9 million km) from Earth and by April 2014 it had crossed the halfway mark in its journey. The follow-up TCM-2 maneuver was originally planned for 9 April, in order to make minor trajectory adjustments in response to solar radiation pressure, but MOM/Mangalyaan was adhering so closely to its pre-planned flight profile that the burn proved unnecessary and was postponed until 11 June. At this point, it had attained a distance of 63.4 million miles (102 million km) from Earth and had traveled 290 million miles (466 million km) of its heliocentric journey.
A third burn was originally planned for August, but also proved unnecessary. “MOM is closely following its trajectory and the mission managers have just ruled out the need for a Trajectory Correction Maneuver, originally planned for August 2014, which means MOM needs only three of the four TCMs originally planned for the heliocentric journey,” explained ISRO on its Facebook page. “All the parameters of the spacecraft are within limits. We will review again in the end of August whether any trajectory correction is needed before its injection in Mars orbit next month.” Last Tuesday (16 September), time-tagged commands to perform the critical Mars Orbit Insertion (MOI) maneuver were uploaded to the spacecraft, followed by a series of instructions for the upcoming TCM-4 burn.
The TCM-4 burn occurred perfectly at 2:30 p.m. IST (5:00 a.m. EDT) Monday, 22 September. It lasted 3.968 seconds and expended about 1.1 pounds (0.5 kg) of propellant. With typical understatement, ISRO noted that “Test Firing of Main Liquid Engine of Mars Orbiter Spacecraft is Successful” on its website. Unlike the TCM-1 and TCM-2 burns, which utilized the spacecraft’s eight 22-Newton attitude-control thrusters, the TCM-4 firing marked the first test of the 440-Newton LAM engine, which had not been fired since the inaugural Earth-departure maneuvers, about 300 days earlier in late 2013.
With the success of TCM-4, it was intended that the LAM and the eight attitude-control thrusters would be fired in tandem for Wednesday’s MOI maneuver. “We are confident the engine will work,” explained Koteshwar Rao, ISRO’s scientific secretary, “but just in case it doesn’t, we have a Plan B that involves firing the eight thrusters for a longer time.” However, Mr. Rao cautioned that employing the 22-Newton thrusters alone would consume a larger quantity of propellant in order to achieve a stable orbit around Mars.
Precisely on time, at 7:17:32 a.m. IST Wednesday (9:47:32 p.m. EDT Tuesday), the LAM roared to life to begin a burn which ran for 1,388.67 seconds—some 24 minutes and 14 seconds—and served to change the velocity of MOM/Mangalyaan by 3,605.6 feet per second (1,099 meters per second). However, due to the communications delay across the interplanetary gulf between Earth and Mars, ISRO controllers were not aware of the start of the successful engine firing until about 12.5 minutes later. The burn concluded at 7:41:46 a.m. IST Wednesday (10:11:46 p.m. EDT Tuesday), having consumed an estimated 550 pounds (249.5 kg) of propellant and established MOM/Mangalyaan into its highly elliptical orbit. Inclined 150 degrees relative to Mars’ equator, the spacecraft requires 72 hours, 51 minutes and 51 seconds to circle its host planet.
The 2,980-pound (1,350-kg) spacecraft is equipped with five discrete scientific instruments—the Methane Sensor for Mars (MSM), Mars Colour Camera (MCC), Mars Exospheric Neutral Composition Analyser (MENCA), Thermal Infrared Spectrometer (TIR), and Lyman-Alpha Photometer (LAP)—and will demonstrate the technology needed to deliver a spacecraft to the Red Planet and conduct meaningful science. Upon arrival, MOM/Mangalyaan will spend at least six months orbiting Mars, focusing on the morphology, topography, and mineralogy of the surface, together with the dynamics of its thin upper atmosphere, its loss of water, the influence of solar wind and radiation, and the nature of its moons, Phobos and Deimos. Hopes are high for the mission, as India sets out on a path to become the fourth discrete organization, nation, or group of nations to successfully send its own mission to Mars. Only Russia, the United States, and the member states of the European Space Agency (ESA) have accomplished this feat to date.
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