Seminar Report on SOLAR SAILS

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Seminar Report on SOLAR SAILS

• Name RAMAKANTH.K
• USN 1SG05EE041
• Department Of Electrical Engineering
  Sapthagiri College Of Engineering

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Introduction

• A solar sail is a spacecraft without an
• engine - it is pushed along directly by
• light particles from the Sun, reflecting off
• giant mirror-like sails. Because it carries
• no fuel and keeps accelerating over almost
• unlimited distances, it is the only technology
• now in existence.

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• What is a solar sail?
• A solar sail, simply put, is a spacecraft
  propelled by sunlight. Whereas a conventional
  rocket is propelled by the thrust produced by its
  internal engine burn, a solar sail is pushed
  forward simply by light from the Sun. This is
  possible because light is made up of packets of
  energy known as photons, that act like atomic
  particles, but with more energy.

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COMPONENTS OF A SOLAR SAIL

• Solar sails are composed of large flat smooth
  sheets of very thin film, supported by
  ultra-lightweight structures. The side of the
  film which faces the sun is coated with a highly
  reflective material so that the resulting product
  is a huge mirror, typically about the size of a
  football field. The force generated by the sun
  shining on this surface is a very gentle force.

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SOLAR SAILING

• Solar sailing is a method of converting light
  energy from the sun into a source of propulsion
  for spacecraft. In essence, a solar sail is a
  giant mirror that reflects sunlight in order to
  transfer the momentum from light particles
  (photons) to the object that is propelling. The
  phrase "solar sails" is often confused with
  "solar cells", which is a technology for
  converting solar light into electrical energy.

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THE CONCEPT OF SOLAR SAILS

• Nearly 400 years ago, as much of Europe was
  still involved in naval exploration of the world,
  Johannes Kepler proposed the idea of exploring
  the galaxy using sails. Through his observation
  that comet tails were blown around by some kind
  of solar breeze, he believed sails could capture
  that wind to propel spacecraft the way winds
  moved ships on the oceans. While Kepler's idea of
  a solar wind has been disproven, scientists have
  since discovered that sunlight does exert enough
  force to move objects. To take advantage of this
  force, NASA has been experimenting with giant
  solar sails that could be pushed through the
  cosmos by light.

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WORKING PRINCIPLE OF SOLAR SAILS How
Does Light Push a Solar Sail?1-Electromagnetism
James Clerk Maxwell developed the laws
describing electromagnetism and concluded that
light is an electromagnetic wave. Maxwell
predicted that when light hits an object and is
absorbed or reflected, the light wave pushes on
electric charges in the surface of the object,
which in turn push on the rest of the object. If
the light is reflected, the object gets pushed
twice as hard, just like a ball bouncing of the
wall. In this process the photons transmit their
momentum to the surface twice-once by the initial
impact, and again by reflecting back from it.
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• 2- A Very Very Gentle Force

Sunlight exerts a very gentle force. A
square mirror 1 kilometer on a side would only
feel about 9 Newtons or 2 pounds of force.
Fortunately, space is very empty and clean
compared to Earth, so there is plenty of room for
a 1 kilometer wide sails to maneuver, and there
is no noticeable friction to interfere with your
9 Newtons of thrust.
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• Solar Sail Materials
•   While solar sails have been designed before,
  materials available until the last decade or so
  were much too heavy to design a practical solar
  sailing vehicle. Besides being lightweight, the
  material must be highly reflective and able to
  tolerate extreme temperatures. The giant sails
  being tested by NASA today are made of very
  lightweight, reflective material that is upwards
  of 100 times thinner than an average sheet of
  stationery.

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• Another organization that is developing solar
  sail technology, the Planetary Society (a
  private, non-profit group based in Pasadena,
  California), supports the Cosmos 1, which boasts
  solar sails that are made of aluminum-reinforced
  Mylar and are approximately one fourth the
  thickness of a one-ply plastic trash bag.

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• ALUMINUM AS SOLAR SAIL MATERIAL
• The thin metal film, according to the preferred
  embodiment of this invention, is an aluminum
  film. Aluminum films have high reflectivity, low
  density, a reasonable melting point, and a very
  low vapor pressure. The reflectivity and
  transmissivity of aluminum film is a function of
  its thickness.
• High deposition rates, near-normal vapor
  incidence, and a good vacuum favor high
  reflectivity.

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• Consequently, any aluminum film thick enough to
  reflect well in the visible wave lengths should
  reflect even better in the infrared, where
  roughly half the sun's power output lies.
• The reflectivity of aluminum films varies with
  the deposition conditions.

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• Aluminium being manufactured for the Solar Sail.

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• USAGE OF REFRACTORY MATERIALS
• Aluminum films of the minimum thickness required
  for reflectivity may prove too weak to support
  the stresses imposed upon them during fabrication
  and operation, or may creep under load at
  elevated temperatures. If so, it is possible to
  strengthen them, not by adding further aluminum,
  but by adding a reinforcing film of a stronger,
  more refractory material. A good reinforcing film
  should be strong, light, and easy to deposit.
• The use of a metal as a reinforcing film could
  reduce the amount of aluminum needed to give good
  reflectance. Some metals, such as nickel, may
  reflect well enough to be of interest by
  themselves.

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• AREA OF CONCERN IN CONSTRUCTION
• Tears are a critical concern in the use of thin
  films for solar sails. While even sheets of
  extremely thin material have adequate strength to
  support the load expected during fabrication and
  operation in the absence of stress
  concentrations, the inevitability of
  manufacturing flaws and micrometeoroid damage
  makes this a small comfort.
• The most obvious method of limiting tears is to
  mount the film on a supporting mesh.
• the mesh adds mass to the sail and, because it
  must be fabricated, transported into space and
  attached to the film, adds cost as well.

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• REMEDY
• A more natural approach to tear-stopping is to
  subdivide the film, convert it from a continuous
  sheet to a redundant network of small,
  load-bearing elements. In such a structure, a
  large manufacturing flow or a grazing
  micrometeoroid impact is free to initiate a
  tear--but the tear will cause the failure, not of
  an entire sheet, but of a small piece of film,
  perhaps 25 square millimeters in area. Patterns
  of cuts and wrinkles can de-tension areas of film
  to isolate stress to smaller regions. Each
  wrinkled region is fabricated with enough extra
  material to avoid being stretched flat as the
  film is tensioned.

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EXAMPLE OF SOLAR SAILS
5.1 Cosmos 1
Cosmos 1 is a small solar sail intented only for
a short mission.
Nevertheless, once it spreads its sails even this
small spacecraft will be 10 stories tall, as high
as the rocket that will launch it. Its eight
triangular blades are 15 meters (49 feet) in
length, and have a total surface area of 600
square meters (6500 square feet). This is about
one and a half times the size of a basketball
court.
. The spacecraft was built in Russia by the
Babakin Space Center under a contract to the
Society. It was launched and operated from Russia.
The purpose of the mission was to conduct
the first solar sail flight. Solar sailing is
recognized as a future planetary flight
technology on the pathway to interstellar flight
(using laser instead of solar photons).
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ADVANTAGES A solar sail is a spacecraft without
a rocket engine. It is pushed along directly by
light particles from the Sun, reflecting off its
giant sails. Because it carries no fuel and keeps
accelerating over almost unlimited distances, it
is the only technology now in existence that can
one day take us to the stars. The major advantage
of a solar-sail spacecraft is its ability to
travel between the planets and to the stars
without carrying fuel. Solar-sail spacecraft
need only a conventional launch vehicle to get
into Earth orbit, where the solar sails can be
deployed and the spacecraft sent on its way.
These spacecraft accelerate gradually, unlike
conventional chemical rockets, which offer
extremely quick acceleration.
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• Solar sails will set new speed records for
  spacecraft and will enable us to travel beyond
  our solar system.

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• Limitations of solar sails
•  
• Solar sails don't work well, if at all, in low
  Earth orbit below about 800 km altitude due to
  erosion or air drag. Above that altitude they
  give very small accelerations that take months to
  build up to useful speeds. Solar sails have to be
  physically large, and payload size is often
  small. Deploying solar sails is also highly
  challenging to date.

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MISUNDERSTANDINGSCritics of the solar sail
argue that solar sails are impractical for
orbital and interplanetary missions because they
move on an indirect course. Another false claim
is that solar sails capture energy primarily from
the solar wind" high speed charged particles
emitted from the sun. These particles would
impart a small amount of momentum upon striking
the sail, but this effect would be small compared
to the force due to radiation pressure from light
reflected from the sail. The force due to light
pressure is about 100 times as strong as that due
to solar wind.
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Future Space Travel Solar sail technology will
eventually play a key role in long-distance NASA m
issions. NASA believes that the exploration of
space is similar to the tale of the "Tortoise and
the Hare," with rocket-propelled spacecraft being
the hare. In this race, the rocket-propelled
spacecraft will quickly jump out, moving quickly
toward its destination. On the other hand, a
rocket less spacecraft powered by a solar sail
would begin its journey at a slow but steady
pace, gradually picking up speed as the sun
continues to exert force upon it. Sooner or
later, no matter how fast it goes, the rocket
ship will run out of power. In contrast, the
solar sail craft has an endless supply of power
from the sun. Additionally, the solar sail could
potentially return to earth, whereas the rocket
powered vehicle would not have any propellant to
bring it back.
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REFERENCES
www.howstuffworks.comwww.wikepedia.orgwww.answer
s.com
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THANK YOU
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Wind sailing
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COSMOS-1 MISSION
The mission of Cosmos-1 occurred in two
phases. Phase 1 will test the deployment of two
solar-sail blades, and Phase 2 will launch the
Cosmos-1 spacecraft into Earth orbit
Launch Vehicle To get Cosmos-1 into Earth
orbit, the spacecraft was loaded into a modified
intercontinental ballistic missile (ICBM) of
Russian design, called the Volna. The ICBM was
launched from a Russian submarine in the Barents
Sea. Typically, the Volna ICBM does not have
enough thrust to reach orbit, but the missile
used for Cosmos-1 will have an added rocket
engine (kick stage) that is used to de-orbit
satellites. The kick-stage engine will provide
the additional thrust required to get Cosmos-1
into orbit.
The Planetary Society Cosmos-1 will be launched
from a submarine.
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• Phase 1
• Phase 1 of the Cosmos-1 Solar Sail
  Project was launched on June 21,2005. The goal of
  Phase 1 was to test the deployment of the solar
  sails. To do this, a payload consisting of two
  inflatable solar-sail blades and a solar-sail
  platform with an imaging camera was packaged
  inside a Volna ICBM and launched from a Russian
  submarine in the Barents Sea. The flight was a
  suborbital flight that lasted about 15 minutes.
  At about 248 mi (400 km) high, the two solar-sail
  blades were deployed. The camera in the platform
  imaged the sail deployment. This test spacecraft
  used an aerobrake to slow down in the upper
  atmosphere and an additional inflatable braking
  device as it approached the ground.

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• Phase 2
• Phase 2 was an orbital flight of the
  actual Cosmos-1 spacecraft. Again, it was
  launched from a Russian submarine on a modified
  Volna ICBM, but the Volna rocket failed, and the
  spacecraft failed to reach orbit. A solar sail
  would have been used to gradually raise the
  spacecraft to a higher earth orbit. The mission
  would have lasted for one month. A suborbital
  prototype test by the group failed in 2001 as
  well, also because of rocket failure.

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Laser assisted light sailing
Light sailing works well for inner planet
missions and for activities extending out to the
Mars orbit. However, the solar flux falls off as
the inverse square of the distance from the sun.
Thus for missions beyond the Jupiter orbit, an
alternative to solar propulsion is to use
directed light from a high power laser. As a
pioneer inventor in the field of interstellar
propulsion, Robert Forward has an avid interest
in developing methods for boosting the intensity
of light that can be delivered to a light sail.
His goal is to reduce the cruise duration of a
trip from our solar system to the nearest star
from 6500 years to a time frame on the order of
40 years.
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5.3 Recent Developments
No solar sails have been successfully
deployed as primary propulsion systems, but
research in the area is continuing

1. On August 9,2004 Japanese ISAS successfully
   deployed two prototype solar sails from a
   sounding rocket. A clover type sail was deployed
   at 122 km altitude and a fan type sail was
   deployed at 169 km altitude. Both sails used 7.5
   micrometer thick film.

2. A joint private project between Planetary
society, Cosmos Studios and Russian Academy of
Science launched Cosmos 1 on June 21,2005, from a
submarine in the Barents Sea, but theVolna rocket
failed, and the spacecraft failed to reach orbit.
A solar sail would have been used to gradually
raise the spacecraft to a higher earth orbit. The
mission would have lasted for one month. A
suborbital prototype test by the group failed in
2001 as well, also because of rocket failure
3. A 15-meter-diameter solar sail (SSP, solar
sail sub payload, soraseiru sabupeiro-do) was
launched together with ASTRO-F on a M-V rocket at
2128, February, 2006 UTC and made it to orbit.
It deployed from the stage at 2146 UTC but
opened incompletely
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Where Solar Sails Can Take Us

• By the end of this decade, there's a good
  chance solar sails will be used for a
  long-distance NASA mission. Flight demos took
  place in early 2005, with a sail-propelled craft
  launched five years later, according to Sarah
  Gavit, program manager for JPL's Solar Sail
  Technology Program. But just how far will these
  solar sails be able to take us and how fast will
  they get us there?

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• Here rocket-propelled spacecraft will quickly
  jump out, moving quickly toward its destination.
  On the other hand, a rocket less spacecraft
  powered by a solar sail would begin its journey
  at a slow but steady pace, gradually picking up
  speed as the sun continues to exert force upon it.

Sooner or later, no matter how fast it goes, the
rocket ship will run out of power. In contrast,
the solar sail craft has an endless supply of
power from the sun. Additionally, the solar sail
could potentially return to Earth, whereas the
rocket powered vehicle would not have any
propellant to bring it back.
As it continues to be pushed by sunlight, the
solar sail-propelled vehicle will build up speeds
that rocket powered vehicles would never be able
to achieve. Such a vehicle would eventually
travel at about 56 mi/sec (90 km/sec), which
would be more than 200,000 mph (324,000 kph).
That speed is about 10 times faster than the
space shuttle's orbital speed of 5 mi/sec (8
km/sec).