MARS ORBITER MISSION PROFILE

MARS ORBITER MISSION PROFILE:

1. Geo Centric Phase

The spacecraft is injected into an Elliptic Parking Orbit by the launcher. With six main engine burns, the spacecraft is gradually maneuvered into a departure hyperbolic trajectory with which it escapes from the Earth’s Sphere of Influence (SOI) with Earth’s orbital velocity + V boost. The SOI of earth ends at 918347 km from the surface of the earth beyond which the perturbing force on the orbiter is mainly due to the Sun. One primary concern is how to get the spacecraft to Mars, on the least amount of fuel. ISRO uses a method of travel called a Hohmann Transfer Orbit – or a Minimum Energy Transfer Orbit – to send a spacecraft from Earth to Mars with the least amount of fuel possible.

2. Helio Centric Phase

The spacecraft leaves Earth in a direction tangential to Earth’s orbit and encounters Mars tangentially to its orbit. The flight path is roughly one half of an ellipse around sun. Eventually it will intersect the orbit of Mars at the exact moment when Mars is there too. This trajectory becomes possible with certain allowances when the relative position of Earth, Mars and Sun form an angle of approximately 44o. Such an arrangement recur periodically at intervals of about 780 days. Minimum energy opportunities for Earth-Mars occur in November 2013, January 2016, May2018 etc.

3. Martian Phase

The spacecraft arrives at the Mars Sphere of Influence (around 573473 km from the surface of Mars) in a hyperbolic trajectory. At the time the spacecraft reaches the closest approach to Mars (Periapsis), it is captured into planned orbit around mars by imparting ∆V retro which is called the Mars Orbit Insertion (MOI) manoeuvre. The Earth-Mars trajectory is shown in the above figure. ISRO plans to launch the Mars Orbiter Mission during the November 2013 window utilizing minimum energy transfer opportunity.

Being delivered to a 250 by 23,500-Kilometer orbit at an inclination of 19.2 degrees, the Mars Orbiter starts out in a type of GSO Transfer Orbit from where it will boost itself into a Trans-Martian Trajectory over a period of four weeks. MOM departs Earth orbit on November 30, 2013 .

This mission design was developed to accommodate the relatively low Payload Capability of the PSLV for an interplanetary mission. A similar profile was being utilized on the Chandrayaan-1 Moon Mission that launched in 2008.

Spending more than four weeks in Earth Orbit requires MOM to be equipped with radiation shielding to endure the numerous passages through Earth’s Radiation Belts.

Over the course of its stay in Earth orbit, MOM fires its Liquid Apogee Motor six times – always when passing perigee to gradually increase the apogee of the orbit to work its way up to departing Earth orbit in a fuel-efficient manner.

The fifth firing places the spacecraft in a 600 by 215,000-Kilometer orbit around Earth and sets up the proper perigee passage for the final engine burn that puts the vehicle onto its Trans-Martian Trajectory.

The trip to Mars takes about 300 days and features a number of Trajectory Corrections. Shortly after TMI, when the precise trajectory has been determined, MOM corrects any insertion errors on its path to Mars. Later in the mission, when the vehicle is approaching the Red Planet, more Trajectory Correction Maneuvers are performed to target the proper position for the important Mars Orbit Insertion Maneuver.

Assuming and on-time launch and Earth Orbit Departure, Mangalyaan reaches Mars on September 24, 2014.