Light Propulsion

Heading toward the ultimate 21st century electromagnetic spacecraft technology

It has always been a fervent dream of scientists to find innovative and intelligent ways to travel to the stars. Now it seems the great "Star Trek" dream is fast becoming a reality.

The solar sail

The idea of light propulsion using the sunlight to exert radiation pressure on large "sails" (known as solar sailing) in space had its humble beginnings in the 1920s. It began in 1924 when the Russian rocket pioneer Fridrikh Tsander suggested interstellar travel could be achieved using mirrors.

The idea was not taken further until in the 1970s when Dr Louis Friedman suggested the idea of solar sailing to Halley's Comet could be a relatively low-cost method of travelling through space. With not too many takers of the idea, he eventually left the Jet Propulsion Lab (JPL) in Pasadena where he co-founded The Planetary Society with the late Dr Carl Sagan and Bruce Murray. Since stepping down from his position as Executive Director of the Society after 30 years of distinguished service, he has focused his attention on solar sail in 2010. He now has become LightSail Program Director for the Society where his expertise in this field has seen him lead the Cosmos 1 project, which would be humanity's first official attempt in space to solar sail.

Prior to making this first serious attempt of an electromagnetic spacecraft, we see in the mid-1980s an attempt on paper by NASA scientists to show the feasibility of a 'solar sail' spacecraft called the Yankee Clipper after observing how the tails of comets are pushed away from the sun by the solar wind. The aim of the NASA spacecraft would use the continuous pressure in sunlight to 'sail' across interplanetary space using a large, thin and solid metallic foil or "sail" attached to a spacecraft for propulsion. However, for some reason, the project has never been put into action. (1)

An artist impression of the Yankee Clipper

UPDATE
October 2002

It seems the reason why NASA has not yet built a solar sail spacecraft is because more effort is being made to improve the sail mechanism for capturing the sunlight so that a much bigger payload could be carried and smaller sails could be used.

Cosmos I

A more advanced version of a "solar-sail'"spacecraft and one that was put into practice came in the early 21st century when Cosmos I was designed on paper and constructed by the US science-based media and entertainment company Cosmos Studios run by Ann Dryan, the widow of the well-known and famous astronomer the late Dr Carl Sagan, and with assistance from The Planetary Society (via Dr Friedman).

After suffering several setbacks during the development and testing phase of Cosmos I, Dryan and her colleague Dr Friedman eventually got to the stage of building the US$4 million (A$5.2 million) 105-kilogram Cosmos I spacecraft. It was launched on 21 June 2005 at the Babakin Space Centre in Russia on a modified Soviet missile with the help of a Russian nuclear submarine in the Barents Sea.

On reaching an Earth's orbit of 825 kilometres above the Pacific Ocean, Cosmos I would have opened up its eight triangular panels measuring 15 metres long made of very thin and lightweight Mylar. Then the light from the Sun would continuously hit these panels, causing the spacecraft to accelerate. The acceleration will be slow at first. But this won't matter too much in the early stages as sunlight will exert a continuous force on the sails. In one hundred days of continuous exertion, the spacecraft will reach 16,000 miles per hour. Eventually the spacecraft will be expected to reach the outer fringes of our solar system in a matter of months at a speed of approximately one-tenth the speed of light (or 160,000 miles per hour). (2)

The spacecraft would have gone into the history books as the one to overtake the Voyager I and II spacecraft in reaching furthest into interstellar space by humankind. However, after its successful launch on 21 June 2005, for some inexplicable reason, no signals from the satellite were picked up. The reason behind the mysterious loss in signal has yet to be determined.

If Cosmos I had not failed, it would have accelerated to the edge of the solar system within 2.4 years. (3)

The magnetic bubble

In a newspaper article published on page D12 of The Canberra Times dated 24 June 2000, an interesting new electromagnetic propulsion idea had been investigated by the American space agency, NASA.

The propulsion system is based on a similar idea to the "solar sail" except this time the area for collecting this solar wind is greatly increased by generating a large "magnetic bubble" (perhaps filled with plasma to help make the bubble swell to a large size). The idea was first proposed by Professor Winglee from the University of Washington in Seattle. With a larger area for collecting the energy in the solar wind, NASA expects to produce a much greater acceleration in their spacecraft.

Yet once again, NASA has been unable to put this idea to practice in this latest attempt from the space agency. Only Cosmos I has been the closest to achieving this first important milestone in the light propulsion field.

But if there is to be faster light propulsion, and with the chance of carrying a heavier payload, the electromagnetic energy in the sunlight has to be concentrated by some means. Is there a way this can be achieved?

The article discussing this concept is available here.

The laser galleon

Philip Norem, the Canadian director of engineering for the Peninsular Research and Development Corporation, gave details of a more concentrated form of light propulsion system, whereby a 1000-ton spaceship, known as the 'laser galleon', could be accelerated to speeds of about 100,000 kilometres per second using an array of highly intensified laser beams on Earth to push the ship along. The 'wind' pressure associated with the laser beams would be picked up by a huge, parachute-shaped sail connected to the front of the ship by a 30-kilometre cable. It is estimated that a journey to the nearest extrasolar star — Proxima Centauri — using such a propulsion system could take only 60 years to complete. (4)

The only problem with this idea is how the energy to propel the spacecraft has to be supplied from the Earth; and the energy can get easily wasted if the spacecraft is not in its light beam.

We also have to consider how massive this spacecraft would be to build if we went ahead with the plan. To travel to the stars in a much shorter period of time, a less massive object will be required.

The new electromagnetic energy recyclers

Now, the time is fast approaching when a new electromagnetic technology discovered in the UFO reports will be applied by humankind. This is the exponential acceleration generated by emitting lare-scale high-frequency radiation from an electrically charged surface. Furthermore, the energy source need not have to be derived entirely from the Earth as in the Laser Galleon proposal. For further details, click here.

Sample references

Kates, William. "A clean-energy way to fly through space": The Canberra Times. 4 October 2002, p.19.

Stemman, Roy. 1991, Mysteries of the Universe. London, England: Bloomsbury Books (an imprint of Godfrey Cave Associates Limited).