Harnessing the power of the Sun to propel a spacecraft may appear somewhat ambitious and
the observation that light exerts a force contradicts everyday experiences. However, it is an
accepted phenomenon that the quantum packets of energy which compose Sunlight, that is to
say photons, perturb the orbit attitude of spacecraft through conservation of momentum; this
perturbation is known as solar radiation pressure (SRP). To be exact, the momentum of the
electromagnetic energy from the Sun pushes the spacecraft and from Newton’s second law
momentum is transferred when the energy strikes and when it is reflected. The concept of
solar sailing is thus the use of these quantum packets of energy, i.e. SRP, to propel a spacecraft,
potentially providing a continuous acceleration limited only by the lifetime of the sail
materials in the space environment. The momentum carried by individual photons is
extremely small; at best a solar sail will experience 9 N of force per square kilometre of sail
located in Earth orbit (McInnes, 1999), thus to provide a suitably large momentum transfer the
sail is required to have a large surface area while maintaining as low a mass as possible.
Adding the impulse due to incident and reflected photons it is found that the idealised thrust
vector is directed normal to the surface of the sail, hence by controlling the orientation of the
sail relative to the Sun orbital angular momentum can be gained or reduced. Using
momentum change through reflecting such quantum packets of energy the sail slowly but
continuously accelerates to accomplish a wide-range of potential missions.solar sails may also be used in deciding the attitude of a spacecraft while in flight.
the observation that light exerts a force contradicts everyday experiences. However, it is an
accepted phenomenon that the quantum packets of energy which compose Sunlight, that is to
say photons, perturb the orbit attitude of spacecraft through conservation of momentum; this
perturbation is known as solar radiation pressure (SRP). To be exact, the momentum of the
electromagnetic energy from the Sun pushes the spacecraft and from Newton’s second law
momentum is transferred when the energy strikes and when it is reflected. The concept of
solar sailing is thus the use of these quantum packets of energy, i.e. SRP, to propel a spacecraft,
potentially providing a continuous acceleration limited only by the lifetime of the sail
materials in the space environment. The momentum carried by individual photons is
extremely small; at best a solar sail will experience 9 N of force per square kilometre of sail
located in Earth orbit (McInnes, 1999), thus to provide a suitably large momentum transfer the
sail is required to have a large surface area while maintaining as low a mass as possible.
Adding the impulse due to incident and reflected photons it is found that the idealised thrust
vector is directed normal to the surface of the sail, hence by controlling the orientation of the
sail relative to the Sun orbital angular momentum can be gained or reduced. Using
momentum change through reflecting such quantum packets of energy the sail slowly but
continuously accelerates to accomplish a wide-range of potential missions.solar sails may also be used in deciding the attitude of a spacecraft while in flight.
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