Satellite Power sub system

POWER SUB-SYSTEM

PRESENTED BY:

SAUTIK MAHATO (20110182)

VINEET CHANCHAL (20110146)

Under the guidance of

Mr. S. Dhar

DEPARTMENT OF ELECTRONICS AND COMMUNICATION SIKKIM MANIPAL INSTITUTE OF TECHNOLOGY

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The power supply system used in satellite employs a solar cell plant which converts solar radiation to electrical energy when the satellite is illuminated by Sun.

During period of eclipse reserve power is provided by 19-cell, nickel-cadmium battery.

To conserve power and allow battery recharging, continuous power is supplied only to those circuits in satellite necessary for ground tracking and command.

INTRODUCTION

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Early communication satellites were limited by the lack of suitable power sources.

Some military surveillance satellites launched by USSR had used thermonuclear generators to supply electrical power.

Was dangerous to the people of Earth if the launch failed.

On March 17, 1958, Vanguard 1 became the second artificial satellite successfully placed in Earth orbit by the United States. It was the first solar powered satellite.

HISTORY

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SPACE-CRAFT

INTELSAT-I

INTELSAT-II

INTELSAT-III

INTELSAT-IV

INTELSAT-IV-A

INTELSAT- V

INTELSAT- VI

YEAR OF LAUNCH

1965 1967 1968 1971 1975 1980 1986

ON ORBIT WEIGHT

34Kg 76Kg 152Kg 595Kg 786Kg 1020Kg 1800Kg

PRIMAR-Y POWER

46W 85W 125W 569W 708W 1220W 3360W

DESIGN LIFE-TIME

1.5years

3 years 5 years 7 years 7 years 10 years

10 years

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Sun was a powerful source of energy

Radiation falling on a spacecraft has an intensity of 1.39 kW/m2

Solar cell was a good alternate source of energy

However efficiency of solar cells is about 10 to 15 %.(Continued)

SUN AS THE ALTERNATE POWER SOURCE

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Solar panels on spacecraft supply power for 2 main uses:

power to run the sensors, active heating, cooling and telemetry.

power for spacecraft propulsion -- electric propulsion, sometimes called solar-electric propulsion.

To increase the specific power, typical solar panels on spacecraft use close-packed solar cell rectangles that cover nearly 100% of the sun-visible area of the solar panels

USE OF SOLAR PANELS

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To date, solar power, other than for propulsion, has been practical for spacecraft operating no farther from the Sun than the orbit of Jupiter

For example Juno,Magellan, Mars Global Surveyor, and Mars Observer used solar power as does the Earth-orbiting, Hubble Space Telescope.

The Rosetta space probe, launched March 2, 2004, will use solar panels as far as the orbit of Jupiter 

The Juno mission (launched 2011) is the first mission to Jupiter (due to arrive in 2016) to use solar panels instead of the traditional RTGs that are used by previous outer solar system missions.[6] It has 60 sq m of panels.

Another spacecraft of interest is Dawn which went into orbit around 4 Vesta in 2011. It is using ion thrusters to get to Ceres

Spacecraft that have used solar power

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What happens when the sun is hidden? Satellites orbiting the Earth pass through a shadow region

on the opposite side of the Earth from the Sun

Depending on the type of orbit, this can happen just a few times a year or every few hours

The solar panels cannot produce electrical energy and the satellite would not only be unable to operate, but would also freeze to incredibly low temperatures (eventually around –270°C)

(Continued)

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There are essentially two ways of storing electrical energy that are used on satellites, both of which rely on reversible chemical reactions.

One is based on cells very similar to those found in portable phones

The other uses so-called ‘fuel cells’, a type of electrical accumulator now being used experimentally in cars and buses.

Unlike a battery, fuel cells generate current rather than simply storing energy. This is achieved by combining hydrogen and oxygen at a platinum membrane, with water as a by-product.

This water can also be accumulated in a tank and successively divided into oxygen and hydrogen by electrolysis, i.e. by letting a current flow through it.

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NUCLEAR POWERED SATELLITES• In satellites, nuclear power is created in Radioisotope

Thermoelectric Generators (RTG's)• Nuclear power is effective in space exploration

satellites going deep into space because they may travel too far from the sun to use solar panels; since a nuclear power source will continue to generate power for an extremely long time, the satellite will have power for all of its long journey in space

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SATELLITE

THANK YOU !