Satellite aims to reveal more about sun

Technicians prepare for the launch of Nasa’s iris satellite, which was sent into orbit on Thursday to study solar weather. Randy Beaudoin / AP Photo

VANDENBERG AIR FORCE BASE, California // From its perch in low-Earth orbit, Nasa's newest satellite will soon get a close-up look at a little-explored region of the sun that is believed to drive space weather that can affect Earth.
The Interface Region Imaging Spectrograph (Iris) satellite was boosted into orbit about 400 miles above Earth by a Pegasus rocket on Thursday evening after a sunset launch. Engineers will test the satellite first before turning on its telescope to stare at the sun.
"We're thrilled," said Nasa's launch director, Tim Dunn, after orbit was achieved.
Unlike a typical launch, Iris began its journey on a plane flown from Vandenberg Air Force Base to a drop point over the Pacific about 160 kilometres off California's central coast. At an altitude of almost 11,900 metres, the plane released the rocket, which ignited its engine and streaked skyward.
Mission controllers anxiously waited as the rocket made the 13-minute climb into space and cheered after learning that Iris had separated from the rocket as planned.
There were some issues. At one point, communications signals were lost and ground controllers had to track Iris using other satellites orbiting Earth. When it came time for Iris to unfurl its solar panels after entering orbit, there was a lag before Nasa confirmed the satellite was generating power.
Previous sun-observing spacecraft have yielded a wealth of information about our nearest star and beamed back brilliant pictures of solar flares.
The 2.1-metre Iris, weighing 45 kilograms, carries an ultraviolet telescope that can take high-resolution pictures every few seconds.
Unlike Nasa's Solar Dynamics Observatory, which observes the entire sun, Iris will focus on a little-explored region that lies between the surface and the corona, the glowing white ring visible during eclipses.
The goal is to learn more about how this mysterious region drives solar wind - a stream of charged particles spewing from the sun - and to better predict space weather that can disrupt communications signals on Earth.
"This is a very difficult region to understand and observe. We haven't had the technical capabilities before now to really zoom in" and peer at it up close, said a Nasa programme scientist, Jeffrey Newmark.
The mission is cheap by Nasa standards, costing US$182 million (Dh668.5m), and is managed by the space agency's Goddard Space Flight Centre.
Iris will gaze at the sun for two years. Before observations can begin, engineers will spend two months conducting health checkups.
Thursday's launch was delayed by a day after a weekend outage cut electricity to a swath of the central coast.
The Pegasus is a winged rocket designed for launching small satellites. First flown in 1990, Pegasus rockets have also been used to accelerate vehicles in hypersonic flight programs.
* Associated Press