Kalam, 79, is a space pioneer who served as the 11th president of India. He and his former associates at the Indian Space Research Organization (ISRO) have teamed with the Washington-based National Space Society (NSS) for an initiative aimed at accomplishing the work necessary to field a system of large satellites that would collect solar energy and beam it safely to Earth’s surface.

“A large mission like space solar power will need the combined efforts of many nations,” Kalam said Nov. 4 in a conference call from India. “I am certain that harvesting solar power in space can upgrade the living standard of the human race.”

U.S. Allies

Kalam was joined on the line by John Mankins, a former exploration chief technologist at NASA who is president of the Space Power Association, and T.K. Alex, director of the ISRO’s Satellite Center in Bengaluru. Alex, who led development of the Chandrayaan-1 lunar orbiter, will join Mankins as co-principal investigators on the Kalam-National Space Society Energy Initiative.

The group plans a bilateral meeting in Huntsville, Ala., next May to establish a course of action and organizational structure.

While NSS CEO Mark Hopkins says that meeting will be organized around Indian and U.S. participants, plans call for broadening the effort to include other nations — notably Japan, which has done advanced work in space solar power.

Kalam says the topic may be included during President Barack Obama’s upcoming summit with Indian Prime Minister Manmohan Singh, but a more likely route to the top levels of spacefaring nations will come in presentations at future G-8 and G-20 economic summits.

Ideally, different nations will contribute SSP components based on their particular skills, he says. For India and the U.S., cooperation in technology development also can work, he adds.

Indian infrastructure

Alex says India already has a significant terrestrial solar power industry based in the country’s north. The nation also is working in multi-junction solar arrays which, while not as advanced as similar technology in the U.S., could lead to the solar-power conversion efficiency needed to make SSP practical. Similarly, Kalam cited India’s work in reusable launch vehicle technology as a way to hold down the cost of getting SSP payloads to orbit, and said that work could go faster if the U.S. and India collaborate.

Mankins cited a “10-10-10” rule for a first prototype in geostationary orbit that could be a goal for the new bilateral initiative.

Such a system would deliver 10 megawatts of power, cost less than $10 billion to build and launch, and be ready in less than 10 years. The system would consist of a large satellite to collect the Sun’s energy and convert it into microwaves, which would be beamed to an antenna on Earth that would collect the microwaves for conversion to electricity and transmission through the existing power grid.

The antenna would be as open as chicken wire, Hopkins says, which would permit farmers to grow crops under it. And the beam would be so diffuse that “you can walk through the beam, even if you’re naked, and it’s not going to hurt you.”

Original source: http://www.aviationweek.com

The concept for the so-called Dyson-Harrop satellite begins with a long metal wire loop pointed at the sun. This wire is charged to generate a cylindrical magnetic field that snags the electrons that make up half the solar wind. These electrons get funnelled into a metal spherical receiver to produce a current, which generates the wire’s magnetic field – making the system self-sustaining.

Any current not needed for the magnetic field powers an infrared laser trained on satellite dishes back on Earth, designed to collect the energy. Air is transparent to infrared so Earth’s atmosphere won’t suck up energy from the beam before it reaches the ground.

Back on the satellite, the current has been drained of its electrical energy by the laser – the electrons fall onto a ring-shaped sail, where incoming sunlight can re-energise them enough to keep the satellite in orbit around the sun.

A relatively small Dyson-Harrop satellite using a 1-centimetre-wide copper wire 300 metres long, a receiver 2 metres wide and a sail 10 metres in diameter, sitting at roughly the same distance from the sun as the Earth, could generate 1.7 megawatts of power – enough for about 1000 family homes in the US.

A satellite with the same-sized receiver at the same distance from the sun but with a 1-kilometre-long wire and a sail 8400 kilometres wide could generate roughly 1 billion billion gigawatts (10²⁷ watts) of power, “which is actually 100 billion times the power humanity currently requires”, says researcher Brooks Harrop, a physicist at Washington State University in Pullman who designed the satellite.

Since the satellites are made up mostly of copper, they would be relatively easy to construct. “This satellite is actually something that we can build, using modern technology and delivery methods,” Harrop says.

Satellites laden with solar panels that can beam their energy down 24 hours a day have been discussed for decades. California agreed last December to a deal involving the sale of space-based solar power. Solar panels cost more per pound than the copper making up the Dyson-Harrop satellites, so according to Harrop, “the cost of a solar wind power satellite project should be lower than a comparative solar panel project”.

So far so good, but there is one major drawback. To draw significant amounts of power Dyson-Harrop satellites rely on the constant solar wind found high above the ecliptic – the plane defined by the Earth’s orbit around the sun. Consequently, the satellite would lie tens of millions of kilometres from the Earth. Over those distances, even a sharp laser beam would spread to thousands of kilometres wide by the time it reached Earth.

“Two megawatts spread across areas that large are meaningless, less than moonlight,” says John Mankins, president of consultancy firm Artemis Innovation which specialises in space solar power. To beam power from a Dyson-Harrop satellite to Earth, one “would require stupendously huge optics, such as a virtually perfect lens between maybe 10 to 100 kilometres across,” he says.

He also points out that the wire could burn out due to the huge current coursing through it, although he has not performed the calculations to gauge the probability of that occurring. But he does say that a smaller version of this “clever and interesting” satellite could help power some space missions. “I could imagine uses for this idea outside of the plane of the ecliptic, such as helping generate power for something like the Ulysses spacecraft, which went around the poles of the sun.”

Source: http://www.newscientist.com/article/dn19497-outofthisworld-proposal-for-solar-wind-power.html?DCMP=OTC-rss&nsref=online-news