The document discusses the power supply systems used in satellites, highlighting the use of solar cells for energy conversion during sunlight exposure and nickel-cadmium batteries for eclipse periods. It outlines the evolution of satellite power sources, including early military satellites that used thermonuclear generators, and emphasizes the increasing reliance on solar energy for spacecraft, particularly for missions beyond the orbit of Jupiter. Additionally, it describes energy storage methods on satellites, such as batteries and fuel cells, as well as the use of nuclear power through radioisotope thermoelectric generators for deep space exploration.

1. 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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2.  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.
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3.  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.
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4. SPACE-CRAFT
INTELS
AT-I
INTELS
AT-II
INTELS
AT-III
INTELS
AT-IV
INTELS
AT-IV-
A
INTELS
AT- V
INTELS
AT- 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
1.5
years
3 years 5 years 7 years 7 years 10
years
10
years
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5.  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)
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6.  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
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7.  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
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8.  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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9.  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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10. • 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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12. THANK YOU !