Moonbeams to Power Earth
Source: Space.com
WASHINGTON -- A solution to world energy woes and rising
gasoline prices might require looking off Earth at our nearest
celestial neighbor -- the moon.
Power-beaming satellites have been advocated for numbers
of years as a way for energy-hungry Earthlings to develop new sources
of power to meet needs in the 21st century.
At the moon, Earth already has a heavenly equivalent to
a wall plug, says David Criswell, director of the Institute for Space
Systems Operations at the University of Houston in Texas.
"There's no need to build the moon," Criswell told
SPACE.com. By mid 21st century, enough lunar solar power can be
imported Earthward to supply the world's population of 10 billion
people to meet all basic human needs, he said.
Solar farms
For the last two decades, Criswell has been on a lunar
crusade of sorts. Starting in the 1970s, he and engineering colleague,
Robert Waldron, promoted the idea of turning lunar soils and rocks
into useful products.
Thanks to the Apollo program, moonwalking astronauts
were the first prospectors of another world. Hundreds of pounds of
lunar samples have been studied, showing great potential for
manufacturing.
The moon: Earth's future power hub?
There are no "magic" resources or technologies needed,
Criswell said. Any handful of lunar dust and rocks will do. That lunar
material contains quantities of silicon oxygen and metals, such as
iron and aluminum, he said.
Lunar dust can be used directly as thermal, electrical
and radiation shields. Also, the dust can be converted into glass,
fiberglass and ceramics, not to mention solar cells, electric wiring,
microcircuitry and other items.
"Solar-cell technology here on Earth is done in vacuum
or near-vacuum conditions. And those conditions are certainly
available on the moon, at almost no cost," Criswell said.
On-the-spot beaming
Criswell envisions that large fields of made-on-the-moon
solar cells can energize sets of microwave transmitters. These
transmitters would be in synch to deliver microwave power to receivers
on Earth.
In order to provide inexpensive electric energy to
Earth, most of the lunar-situated hardware must be manufactured on the
spot, Criswell said. Some high-technology items would be ferried to
the moon from Earth, he said.
Pairs of solar farms would be planted in the lunar
highlands, on the east and west limbs of the moon, near the equator.
As part of the Lunar Solar Power System, beams of
microwaves from the moon are directed to receiving antennas on Earth
called "rectennas". They operate when they are in view of the moon.
Simple reflectors or active re-transmitters in Earth orbit can
redirect energy beams to ground rectennas at times when they are not
in sight of the moon.
Solar sails circling the moon would be required to
reflect sunlight down to the lunar sites, especially when the moon is
in eclipse of Earth, and when the
site is no longer in sunlight.
"The more sunlight that can be directed to the site,
then the more energy output for Earth," Criswell said.
Not only Earth could benefit from moon beaming.
In full operation, re-targeted lunar-based transmitters
could supply power out past Jupiter, Criswell said.
Step-by-step plans
How soon can a Lunar Solar Power System plan be started?
"This is like having a baby. You can have it in 100 years or 10
years," Criswell said. "It can be
done in 10-year increments," he said.
A first step would be 10 years of planning -- sketching
out business plans and carrying out hardware demonstrations here on
Earth. Building up the technical community to run such a lunar power
base is key, Criswell said.
To demonstrate the idea's practicality, sets of
lunar-landing robots can be dispatched to the moon. Once there, they
would unfurl solar arrays, then operate in tandem to transmit a
collective low-energy beam back to Earth.
"This type of activity could be started very quickly,"
Criswell said. Follow-on stages would mean sending equipment to the
moon, showing how products can be made of lunar soil and rock.
Eventually, the moon would be dotted with factories,
robot tractors and repair shops -- all part of building up the Lunar
Solar Power System, Criswell said.
Given the closeness of the moon, one-way radio signals
from Earth take only 1.3 seconds to cross space. On-duty robots,
controlled from Earth could do the building, operation and maintenance
of lunar power-beaming sites, Criswell said. "You will need some
people, but how many, I'm not sure at this point," he said.
The price tag for bringing the moon on line, and
churning out power for Earth is about $150 billion, roughly twice the
cost of the Apollo program in today's
dollars, Criswell said. Capable of churning out more and more power
over the years, by 2015, 1,000 gigawatts of power could be pumped to
Earth from the moon, he said.
"Everybody's grandchildren right now would be energy
prosperous by 2050," he said. "If you don't have access to cheap
energy, that's one of the things like
not having enough air."
Weaning the Earth off our current carbon-based energy
system is a must, Criswell said. "Otherwise we're going to stay in a
precarious situation. If you want a prosperous world, there just are
no other options," he added.
Robots need supervision
Not everyone is ready to hook up to Criswell's lunar
power supply, however.
"My own feeling is that he may well be right, but the
idea is downstream," said Bryan Erb, president of the Sunsat Energy
Council, based in Houston, Texas. The group backs a first-things-first
approach, namely the building of satellite power stations in Earth
orbit.
"It takes a big investment to get back to the moon," Erb
said. "I just don't see a graceful migration path to get to a lunar
power system without a massive
up-front investment," he said.
Erb said he views the Criswell proposal as a "vast
undertaking" that would be very costly. "If you could overcome that
hurdle, then there's a lot of promise in his idea of using the moon,"
he said.
Taking a wait-and-see attitude is Paul Werbos, program
director for control networks and computational intelligence at the
National Science Foundation. He recently co-sponsored with NASA a
workshop that looked over the Criswell plan, among other
space-research issues.
"We don't have a definite verdict, but I am much more
optimistic than before," Werbos said. "The opportunity is so great, we
should not lose the
opportunity."
Werbos said that a critical aspect of Criswell's idea is
use of tele-autonomy, that is, how to coordinate human beings on Earth
with on-the-job robots stationed on the moon. "That's the key concept
in my mind in order to build any kind of large-scale space power
system -- on the Earth or on the moon," he said. "How do you get
robots smart enough to do their job under a kind of loose supervision
arrangement?"
http://www.space.com/businesstechnology/technology/lunar_power_000712.
html