MISSION
PROFILE MANGALYAAN
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.
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.
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.
Official Link of Mangalyaan: http://www.isro.gov.in/pslv-c25-mars-orbiter-mission
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