Proposed Pinhole Camera in Space

"Colorado U. proposal for imaging distant planets funded for further study
A NASA institute has selected a new University of Colorado at Boulder
proposal for further study that describes how existing technologies can be
used to study planets around distant stars with the help of an orbiting
"starshade."

The concept by CU-Boulder Professor Webster Cash of the Center for
Astrophysics and Space Astronomy was one of 12 proposals selected for
funding Sept. 28 by the NASA Institute for Advanced Concepts, or NIAC.
Cash's proposal details the methods needed to design and build what
essentially is a giant "pinhole camera" in space.

The football field-sized starshade would be made of thin, opaque material
and contain an aperture, or hole, in the center roughly 30 feet in diameter
to separate a distant planet's light from the light of its adjacent parent
star, Cash said. A detector spacecraft equipped with a telescope would
trail tens of thousands of miles behind the orbiting starshade to collect
the light and process it.

Such a system could be used to map planetary systems around other stars,
detect planets as small as Earth's moon and search for "biomarkers" such as
methane, water, oxygen and ozone. Known as the New Worlds Imager, the
system also could map planet rotation rates, detect the presence of weather
and even confirm the existence of liquid oceans on distant planets, he
said.

"In its most advanced form, the New Worlds Imager would be able to capture
actual pictures of planets as far away as 100 light-years, showing oceans,
continents, polar caps and cloud banks," said Cash. If extra-terrestrial
rainforests exist, he said, they might be distinguishable from deserts.

"To me, one of the most interesting challenges in space astronomy today is
the detection of exo-solar planets," said Cash. "We have created an
affordable concept with very practical technology that would allow us to
conduct planet imaging in visible and other wavelengths of light."

The beauty of the pinhole as an optical device is that it functions as an
almost perfect lens, said Cash, who is a professor in CU-Boulder's
astrophysical and planetary sciences department. 'This device would remove
the limiting problem of light scattered from the parent star due to optical
imperfections."

The successful proposal was authored by Cash, Princeton University's Jeremy
Kasdin and Sara Seager of the Carnegie Institution of Washington. Nine
other proposal advisers from universities and industry contributed to the
New Worlds Imager concept, said Cash.

NIAC was created in 1998 to solicit revolutionary concepts from people and
organizations outside the space agency that could advance NASA's missions.
The winning concepts, chosen because they "push the limits of known science
and technology," are expected to take at least a decade to develop if they
eventually are selected for a mission flight, according to NASA.

In 1999, Cash headed a winning NIAC proposal for a new, powerful x-ray
telescope technology that will allow astronomers to peer into the mouths of
black holes. That telescope package is now under development by NASA as the
multi-million dollar MAXIM mission and is slated for launch next decade.

Other concepts funded in 2004 by NIAC include a proposal for a lunar space
elevator, new super-conducting magnet technology for astronaut radiation
protection and a magnetized beam plasma-propulsion system.

Teams that submitted winning proposals to NIAC this year were awarded
$75,000 for a Phase 1, six-month viability study. Those proposals that go
on to win approval for Phase 2 studies next year by the space agency will
be funded with up to $400,000 for two additional years, according to NASA.

"We are thrilled to team up with imaginative people from industry and
universities to discover innovative systems that meet the tremendous
challenge of space exploration and development," said NIAC Director Robert
Cassanova. Cassanova also is a member of the Universities Space Research
Association, which administers NIAC for NASA. "