SANDUSKY, Ohio (AP) -- Scientists working with a
synthetic material 100-times thinner than a piece of paper are testing their
theory that the sun can power interplanetary spacecraft. They believe that
streams of solar energy particles called photons can push a giant, reflecting
sail through space the way wind pushes sailboats across water.
The
National Aeronautics and Space Administration has invested about $30 million in
space-sail technology, something that existed solely in science-fiction novels
a decade ago. Yet the reflective solar sail could power missions to the sun and
beyond within a decade.
"It's
OK to breathe on it and touch it," said David Murphy, of ATK Space
Systems, showing off the sail.
ATK
Space Systems, based in California,
is one division of a $2.4 billion company that makes rocket motors, advanced
weapons systems and ammunition for the military and the Department of Homeland
Security. It has about 14,000 employees at operations in 23 states.
Last
year it delivered 1.2 billion rounds of small-caliber ammunition to the Army.
The
Space Systems division developed the solar sail, which is being tested in the
world's largest vacuum chamber at the Cleveland-based NASA
Glenn Research
Center's Plum Brook Station in Sandusky. It has a space
environment simulation chamber 100 feet in diameter and 122 feet high.
In
that chamber, Murphy displayed four silvery, triangular pieces of sail
stretched over four long booms, which form a square about 70 feet on each side.
Murphy and others want to study how the sails will deploy and operate in a
vacuum under various temperatures.
"We're
going to cool it down and shake it out," Murphy said.
Just
in case, the fabric, which resembles Mylar, has rip-stop threads to keep it
from pulling apart when the chamber is closed and the air is pumped out.
"To
get a lower pressure you'd have to go to space," said Edward Montgomery,
an engineer from NASA's Marshall Space Flight Center in Huntsville, Ala.
The
chamber has been used to test rocket components, radiators for the
International Space Station and the crash bags that protected twin rovers when
they landed on Mars last year.
The
plastic-like fabric used to make the sails is a spin-off from technology used
to develop spacecraft paint.
First
missions -- scientific payloads of a few hundred pounds -- are likely to be to
the inner planets, Venus and Mercury, and to the sun. But NASA scientists think
the technology is a good bet for eventually powering spacecraft into deep
space.
Since
its fuel is free and doesn't have to be stored, a craft with solar sails would
not have to slingshot around the moon or other planets for a gravity boost to
reach distant destinations, as other craft do.
Craft
propelled by solar sails could be launched on conventional rockets or released
from space stations. In space, the force of sunlight would push the reflective
sails, causing the craft to move, said NASA Marshall physicist Les Johnson.
The
first sail tested in space will be about 130 feet on each side. Those on an
actual mission could be twice as large.
While
its thrust is low, it would be continuous so that the craft accelerates
steadily, eventually reaching speeds of tens of thousands of miles an hour.
Changing the sail's angle to the sun would allow the craft to slow down or
speed up.
"Just
by morphing its shape we can get it to turn," Montgomery said.
With
the science worked out, Murphy said, it is now a matter of building larger
sails.
"We
have everything we need to do this," he said.