CORRECTED-NASA telescope to probe long-standing solar mystery

June 27, 2013|Reuters

(Corrects launch day to Thursday from Friday in paragraph 10)

* IRIS to study how sun heats up its atmosphere

* Surface of the sun is much cooler than the corona

By Irene Klotz

CAPE CANAVERAL, Fla., June 27 (Reuters) - A small NASA
telescope was poised for launch on Thursday on a mission to
determine how the sun heats its atmosphere to millions of
degrees, sending off rivers of particles that define the
boundaries of the solar system.

The study is far from academic. Solar activity directly
impacts Earth's climate and the space environment beyond the
planet's atmosphere. Solar storms can knock out power grids,
disrupt radio signals and interfere with communications,
navigation and other satellites in orbit.

Space Systems Advanced Technology Center in Palo Alto,
California, which designed and built the telescope.

Scientists have been trying to unravel the mechanisms that
drive the sun for decades but one fundamental mystery endures:
How it manages to release energy from its relatively cool,
10,000 degree Fahrenheit (5,500 degree Celsius) surface into an
atmosphere that can reach up to 5 million degrees Fahrenheit
(2.8 million Celsius).

At its core, the sun is essentially a giant fusion engine
that melds hydrogen atoms into helium. As expected, temperatures
cool as energy travels outward through the layers. But then in
the lower atmosphere, known as the chromosphere, temperatures
heat up again.

Pictures and data relayed by the Interface Region Imaging
Spectrograph, or IRIS, telescope may finally provide some
answers about how that happens.

will be observing the sun from a vantage point about 400 miles
of light moving from the sun's surface, known as the
photosphere, into the chromosphere. Temperatures peak in the
sun's outer atmosphere, the corona.

All that energy fuels a continuous release of charged
pressure bubble that fills and defines the boundaries of the
solar system.

at NASA headquarters in Washington, D.C.

The telescope is scheduled to be launched aboard an Orbital
Sciences Corp Pegasus rocket on Thursday at 10:27 p.m.
EDT (0227 GMT Saturday). Pegasus is an air-launched system that
is carried aloft by a modified L-1011 aircraft that will take
off from Vandenberg Air Force Base in California about 55
minutes before the scheduled launch.

The rocket is released from the belly of the plane at an
altitude of about 39,000 feet (11,900 meters) so it can ignite
and carry the telescope into orbit.

IRIS, which cost about $145 million including the launch
service, is designed to last for two years.

(Editing by Kevin Gray and Eric Walsh)