Tuesday, November 5, 2013

Powered from Space

India’s ambitious Mars Mission saw a successful launch today. The 1350 kg satellite was placed in an elliptical earth orbit from where it will be transfered into a heliocentric one and from there to Mars will be the last leap. The 400 million km odyssey will take around a year roughly, if everything goes smoothly.

The craft carries 850 kilograms of propellant and oxidiser.
Propellant is the chemical mixture burned to produce thrust in rockets and consists of a fuel and an oxidizer. By controlling the flow of propellant to the combustion chamber, the engine can be throttled, stopped, or restarted. The main engine uses the bipropellant combination monomethyl hydrazine and dinitrogen tetroxide for orbit insertion and other manoeuvres. But the craft is largely powered by solar cells.

Some of Nasa’s deep space probes have relied mostly on a certain type of plutonium, plutonium-238. It powers these spacecraft with the heat of its natural decay. But plutonium-238 isn't found in nature; it's a byproduct of nuclear weaponry and tough to lay hands on! Solar power is preferable to plutonium because it is cheaper and has fewer safety concerns, but obviously will not work as the craft moves away from the sun.
Fuel cells, devices that transform the chemical energy of hydrogen into electrical energy through their reaction with oxygen and feed the electricity to run an electric engine, were first employed in space missions in the 1960s. Due to their high efficiency and their water vapor emissions (no CO), hydrogen fuel cells have triggered global research efforts to reduce greenhouse gas and air pollutant emissions. But they are costly and global research at present focuses on the automobile sector.

That is all about fuel for man’s ambitious space ventures. However, a by-product of the space missions throws up energy potentials for the energy-starved earth. For instance, with space shuttles becoming as risk-free as any flight, we could think of setting up solar arrays in space.
Without the obstacles like rain, clouds and nighttime, these would receive more concentrated solar rays than they would on Earth. The panels also wouldn't be subject to the seasonal fluctuations that are unavoidable on Earth. Solar energy becomes ever present!

olar panels would either be attached to orbiting satellites or stationed on the moon and the electricity created would be converted into microwaves and beamed down to Earth. Rectifying antennas on the ground would collect the microwaves and convert them back into electricity. Communications satellites already do something very similar when they transmit your cell phone conversations. Some people have even suggested that the solar panels could piggyback on communications satellites. Space-based solar power is a hot favourite as all of the necessary equipment and technology is already developed and understood.

Recent proposals talk of small satellites fitted with solar arrays circling the Earth continuously. They would be more manageable than huge ones and still produce considerable energy output. A satellite less than 1,000 feet (300 meters) across orbiting 300 miles (540 kilometers) above Earth could potentially power 1,000 homes. The major obstacle right now, as with any new technology, is cost. Launching, setting up and maintaining a solar farm on the moon would require vast amounts of manpower and money.

But just as space missions were once the subject of fiction, so also any new technology will seem tough. Not impossible. And energy is what the Blue Planet needs desperately, after food and water.

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