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.