ContentsSphere of Influence (SOI):............................................................................................................................1

Propellant System of MOM.........................................................................................................................2

What is Liquid Propellants?.....................................................................................................................3

Cryogenic propellants..........................................................................................................................3

Hypergolic propellants (Used in MOM................................................................................................3

The oxidizer.........................................................................................................................................4

What is Solid Propellants ?......................................................................................................................4

What is Hohmann transfer?....................................................................................................................4

How you will know that the orbiter is travelling in right direction in deep space?......................................5

Range Finder & Speed.................................................................................................................................6

What is Doppler shift ?............................................................................................................................6

Doppler In Measuring Distance Star Movement..................................................................................7

MOM’s Radiation challenge!.......................................................................................................................8

Van Allen radiation belt.......................................................................................................................8

Magnetic Field of Mars?..........................................................................................................................9

Rad..........................................................................................................................................................9

The gray...............................................................................................................................................9

The curie..............................................................................................................................................9

Orbital Inclination....................................................................................................................................9

Ascending Node and Descending Node.............................................................................................11

Attitude In space....................................................................................................................................12

Orbital Eccentricity................................................................................................................................13

Semi-major axis.....................................................................................................................................13

Sphere of Influence (SOI):The Sphere of Influence is nothing but the bending the space time fabric (gravity as per Einstein's theory).The Sun is much more massive than any of the planets (332,946 times more

massive than Earth) and its gravity dominates the Solar System. Only very near to the planets, the

planetary gravity become stronger than that of the Sun. This region around the planet is referred to as the Sphere of Influence (SOI) of that planet. 

SOI of Earth is 9.25 lakh km. Orbits of the Moon and all the artificial satellites of Earth fall inside this sphere

Sun's sphere of influence is the region where the gravity of Sun dominates as compared to the rest of the galaxy. This region extends up to about two light years which is well beyond the orbit of Pluto.

Propellant System of MOM The propellants namely Monomethylhyrdazine and Nitrogen Tetroxide (both Liquid

Propellants ) are stored in Titanium tanks with a combined storage capacity of 852 Kg.

This being a pressure fed system, about 67 litres of Helium is used to pressurise the propellants into the combustion chamber.

What is Liquid Propellants?In a liquid propellant rocket, the fuel and oxidizer are stored in separate tanks, and are fed through a system of pipes, valves etc. to a combustion chamber where they are combined and burned to produce thrust. Liquid propellant engines are more complex than their solid propellant counterparts, however, they offer several advantages. By controlling the flow of propellant to the combustion chamber, the engine can be throttled, stopped, or restarted.

A good liquid propellant is one with a high specific impulse or, stated another way, one with a high speed of exhaust gas ejection. This implies a high combustion temperature and exhaust gases with small molecular weights. However, there is another important factor that must be taken into consideration: the density of the propellant. Using low-density propellants means that larger storage tanks will be required, thus increasing the mass of the launch vehicle. Storage temperature is also important. A propellant with a low storage temperature, i.e. a cryogenic, will require thermal insulation, thus further increasing the mass of the launcher. The toxicity of the propellant is likewise important. Safety hazards exist when handling, transporting, and storing highly toxic compounds

Cryogenic propellants are liquefied gases stored at very low temperatures, most frequently liquid hydrogen) as the fuel and liquid oxygen as the oxidizer. Hydrogen remains liquid at temperatures of -253 Degree Celsius and oxygen remains in a liquid state at temperatures of -183 Degree Celsius

Because of the low temperatures of cryogenic propellants, they are difficult to store over long periods of time. For this reason, they are less desirable for use in military rockets that must be kept launch ready for months at a time. Furthermore, liquid hydrogen has a very low density (0.071 g/ml) and, therefore, requires a storage volume many times greater than other fuels. Despite these drawbacks, the high efficiency of liquid oxygen/liquid hydrogen makes these problems worth coping with when reaction time and storability are not too critical. Liquid hydrogen delivers a specific impulse about 30%-40% higher than most other rocket fuels.Liquid oxygen and liquid hydrogen are used as the propellant in the high efficiency main engines of the Space Shuttle.

Hypergolic propellants (Used in MOM) are fuels and oxidizers that ignite spontaneously on contact with each other and require no ignition source. The easy start and restart capability of hypergols make them ideal for spacecraft maneuvering systems. Also, since hypergols remain liquid at normal temperatures, they do not pose the storage problems of cryogenic propellants. Hypergols are highly toxic .

Hypergolic fuels commonly include hydrazine, monomethyl hydrazine (MMH) and unsymmetrical dimethyl hydrazine (UDMH). Hydrazine gives the best performance as a rocket

fuel, but it has a high freezing point and is too unstable for use as a coolant. MMH is more stable and gives the best performance when freezing point is an issue, such as spacecraft propulsion applications.

The oxidizer is usually nitrogen tetroxide (NTO) or nitric acid. Nitrogen tetroxide is less corrosive than nitric acid and provides better performance, but it has a higher freezing point. Consequently, nitrogen tetroxide is usually the oxidizer of choice when freezing point is not an issue, however, the freezing point can be lowered with the introduction nitric oxide. The resulting oxidizer is called mixed oxides of nitrogen (MON).

What is Solid Propellants ?Solid propellant motors are the simplest of all rocket designs. They consist of a casing, usually steel, filled with a mixture of solid compounds (fuel and oxidizer) that burn at a rapid rate, expelling hot gases from a nozzle to produce thrust. When ignited, a solid propellant burns from the center out towards the sides of the casing. The shape of the center channel determines the rate and pattern of the burn, thus providing a means to control thrust. Unlike liquid propellant engines, solid propellant motors cannot be shut down. Once ignited, they will burn until all the propellant is exhausted.(Hence Not Used In MOM because Required Restarting of Engine)

The Travelling Wave Tube Amplifier generates 210 W RF power.

It's not the shortest route. The shortest distance between Mars and Earth is 54.6 million km. launching in the shortest route possible to Mars and then, decelerating to match the planet's speed, would require an extremely large amount of fuel.

The motion of MOM is hyperbolic after it has achieved the escape velocity. Then, once it crosses the Earth's sphere of influence (SOI), it follows the elliptical orbit around sun. This is because, outside Earth's SOI, Sun's gravitation is the dominant one.

The route which requires least amount of fuel is an elliptical orbit which forms a tangent to the Mars' and Earth's Orbit around sun. MOM is traveling a distance of about 680 million km in this elliptical trajectory. This kind of transfer is called a Hohmann transfer.

What is Hohmann transfer? When travelling among the planets, it's a good idea to minimize the propellant mass

needed by your spacecraft and its launch vehicle. That way, such a flight is possible with current launch capabilities, and costs will not be prohibitive. The amount of propellant needed depends largely on what route you choose. Trajectories that by their nature need a minimum of propellant are therefore of great interest.

To launch a spacecraft from Earth to an outer planet such as Mars using the least propellant possible, first consider that the spacecraft is already in solar orbit as it sits on the launch pad. This existing solar orbit must be adjusted to cause it to take the spacecraft to Mars: The desired orbit's perihelion (closest approach to the sun) will be at the distance of Earth's orbit, and the aphelion (farthest distance from the sun) will be at the distance of Mars' orbit. This is called a Hohmann Transfer orbit. The portion of the solar orbit that takes the spacecraft from Earth to Mars is called its trajectory.

There will be one opportunity for a Hohmann transfer in every synodic period of the planet. Synodic period for a planet is the time it takes to return to the same position relative to sun as seen from earth Earth. Synodic period for Mars is 780 Days (almost two years).

Hohmann transfer to Mars is possible when Mars is ahead of Earth by an angle of about 44 degree, when measured at the centre of Sun. So, Hohmann transfer opportunity to Mars is present in almost every alternate years.

How you will know that the orbiter is travelling in right direction in deep space?

Range, velocity and angular measurements performed periodically to determine the orbit of the spacecraft and to compare it with the predicted trajectory. MOM uses radio based techniques for ranging. MOM is also equipped with Delta-Differential One-way Ranging capability which provides improved angular measurements which is essential for interplanetary missions.

Range Finder & Speed A coded ranging pulse is sent to spacecraft to measure its distance from ground. When

the spacecraft receives this pulse, it returns the pulse on its down-link. The distance to the spacecraft and ground station can be computed from the delay between sending and receiving this pulse. The speed at which the spacecraft is moving away from the ground station is determined by measuring the Doppler shift.

What is Doppler shift ?

When the source of the waves is moving toward the observer each wave takes slightly less time to reach the observer than the previous wave. Therefore the time between the arrival of successive wave crests at the observer is reduced causing an increase in the frequency.

Conversely, if the source of waves is moving away from the observer, each wave is emitted from a position farther from the observer than the previous wave, so the arrival time between successive waves is increased, reducing the frequency.

A car engine sound higher in pitch when it is approaching than when it is receding. The pink circles are sound waves. When the car is moving to the left, each successive wave is emitted from a position further to the left than the previous wave. So for an observer in front (left) of the car, each wave takes slightly less time to reach him than the previous wave. The waves "bunch together", so the time between arrival of successive wavefronts is reduced, giving them a higher frequency. The waves "stretch apart",(Right) so the time between the arrival of successive wave-fronts is increased slightly, giving them a lower frequency

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Doppler In Measuring Distance Star Movement :( Daily NASA come up With another Distance star/Planet/Galaxy)Observers looking at an object that is moving away from them see light that has a longer wavelength than it had when it was emitted (a redshift), while observers looking at an approaching source see light that is shifted to shorter wavelength (a blueshift).

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MOM’s Radiation challenge!

The two doughnut shaped blankets that shroud the Earth with highly charged plasma particles comprising of electrons, protons and nuclei are called Van Allen Radiation belts.MOM has successfully sustained several passes of these lethal radiation belts speculated to have been formed by furious solar winds and harmful cosmic rays.These belts are a part of Earth’s inner magnetosphere and stretch from an altitude of 1000 km to 60,000 km above Earth.

Prolonged exposure to these belts poses a significant threat to various sensitive components of a spacecraft.ISRO's Mars Orbiter Mission spacecraft is designed with sufficient safeguards against such fatal particles

Van Allen radiation belt is one of at least two layers of energetic charged particles (plasma) that is held in place around the planet Earth by the planet's magnetic field. The belts extend from an altitude of about 1,000 to 60,000 kilometers above the surface in which region radiation levels vary. Most of the particles that form the belts are thought to come from solar wind and other particles by cosmic rays.

Magnetic Field of Mars?Scientists think that Mars had a global magnetic field like that of Earth, which was disappeared billions of years ago. Without the protection of this magnetic field, most of the water and atmosphere escaped from Mars. In the absence of Magnetic field, radiation belts also won't sustain.

All the parts used in MOM have been evaluated successfully against a radiation of up to 12 krads. This gives a safety margin factor of 2 after considering the kind of radiation MOM is exposed to, during Geocentric, Heliocentric and Martian orbits put together.

Rad : The rad is a deprecated unit of absorbed radiation dose. Silicon-based microelectronics break down under exposure to radiation. Radiation-hardened components designed for military or nuclear applications can survive up to 10 gigarad .

1 rad = 0.01 Gy = 0.01 J/kg

25 rad:lowest dose to cause clinically observable blood changes

1krad: typical radiation tolerance of ordinary microchips

1Mrad:typical tolerance of radiation-hardened microchips

The gray (symbol: Gy) is the SI derived unit of radiation absorbed dose (same as Rad).

I Gy = 100 Rad = 0.1 Krad

The curie (symbol Ci) is a unit of radioactivity, named after Marie and Pierre Curie.

Orbital Inclination

Inclination for an orbit around Earth is the angle between the orbital plane and the equatorial plane.

Orbit of Mars around sun has an inclination of 1. 85 degrees with respect to the Earth's Orbital plane around sun (ecliptic plane).When the spacecraft is escaping tangential to Earth's orbit around sun, inclination of this departure trajectory is an important factor to be considered, to precisely target the insertion in to Martian Sphere of Influence. Hence, inclination of departure trajectory and inclination of earth bound orbits are important elements considered in the trajectory design

Equatorial plane is 23.4° tilted with respect to ecliptic, Mars' axial tilt is 25.19°, and orbit of Mars around Sun is 1.85° tilted with respect to ecliptic plane.

PSLV has injected the spacecraft to an orbit with an inclination of 19.2° with respect to equatorial plane. Now, when we plan Tran-Mars Injection Manouever, in to an orbit around Mars with an inclination of 150°, to optimize the fuel consumption and to limit the out of plane manouevers to the least amount required, geometry of all the above inclinations, are accounted in the calculations.

Ascending Node and Descending Node

Orbital nodes for an orbit around Earth are the two points where the orbit intersects the equatorial plane. 

The node from which the satellite ascends northwards in the orbital plane is called the ‘ascending node’ whereas the node from which the satellite descends southwards is called the ‘descending node’. The line joining the ascending and descending nodes is called ‘Line of nodes’.

Attitude In space When space scientists talk about attitude in technical context, they mean the way the

spacecraft is oriented in 3-dimensional space. Attitude = pitch, yaw and roll.

Orbital Eccentricity

The Eccentricity of an orbit is a numerical representation of the shape of the orbit. Eccentricity is an indication of the extent of deviation of an orbit with respect to a perfect geometric circle.

Eccentricity of a perfectly circular orbit is zero. Eccentricity of an elliptical orbit varies between zero and one. Eccentricity of a parabolic escape orbit is exactly equal to one and that of a hyperbolic orbit is greater than one

Semi-major axis

The semi-major axis of an orbit represents the size of the orbit. Semi-major axis is the distance measured from

the centre of the ellipse to either the Periapsis or the Apoapsis. 

The nearest and farthest points in the orbital plane of any satellite around a celestial body, from the centre of the celestial body, are defined as Periapsis and Apoapsis respectively.

The Eccentricity and Semi-major axis can together uniquely establish the shape and size of a given orbit.

EBN = Earth Burn

Name :Anmol Singh

List of reference

http://www2.jpl.nasa.gov/basics/bsf4-1.php

http://www.braeunig.us/space/propel.htm

ISRO official Facebook Page (Updated about MOM)

cornell.edu

nasa.gov

http://isro.gov.in/

Wikipedia (Sorry for breaking the rule But could not avoid) & crosschecked with different sources too.