Space telescope to unravel mysteries of solar wind

28 June 2013
By Edd Gent
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An Orbital Sciences Pegasus rocket carrying the IRIS spacecraft takes off attached to a modified L-1011 aircraft (CREDIT: NASA)

An Orbital Sciences Pegasus rocket carrying the IRIS spacecraft takes off attached to a modified L-1011 aircraft (CREDIT: NASA)

A space telescope launched today could improve our understanding of the solar wind and how it can affect technology on Earth.

The Interface Region Imaging Spectrograph (IRIS) spacecraft was launched into orbit early this morning 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 and solar storms can knock out power grids, disrupt radio signals and interfere with communications, navigation and other satellites in orbit.

"We live in a very complex society and the sun has a role to play in it," said physicist Alan Title, with Lockheed Martin Space Systems Advanced Technology Center in Palo Alto, California, which designed and built the telescope.

The mission is designed to observe how solar material moves, gathers energy and heats up as it travels through a little-understood region in the sun's lower atmosphere.

This interface region between the sun's photosphere and corona powers its dynamic million-degree atmosphere and drives the solar wind and is also is where most of the sun's ultraviolet emissions, which impact the near-Earth space environment and Earth's climate, are generated.

An enduring mystery the mission will try to unravel is how it manages to release energy from its relatively cool 5,500°C surface into an atmosphere that can reach up to 2.8 million °C .

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.

The 1.2m long, 204kg observatory will be watching the sun from a vantage point about 400 miles above Earth and is designed to capture detailed images 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.

"We are thrilled to add IRIS to the suite of NASA missions studying the sun," said John Grunsfeld, NASA's associate administrator for science in Washington. "IRIS will help scientists understand the mysterious and energetic interface between the surface and corona of the sun."

The telescope was launched at 10:27pm EDT yesterday (2.27am GMT today) aboard an Orbital Sciences Pegasus rocket, an air-launched system that is carried aloft by a modified L-1011 aircraft that took off from Vandenberg Air Force Base in California about 57 minutes before launch.

The rocket was released from beneath the belly of the plane at an altitude of about 39,000 feet (11,900 meters) before it ignited to carry the telescope into orbit.

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

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