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 CO₂), 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!
Solar 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.