NASA Successfully Launches Science Satellite Quintet
NASA's five THEMIS satellites launch spaceward atop a Delta 2 rocket in a Feb. 17, 2007 liftoff from Cape Canaveral Air Force Station in Florida.
Credit: NASA TV.

Five NASA probes blasted into space Saturday, kicking off a two-year mission to hunt down the source of some of Earth's most colorful auroral displays.

After two delayed attempts, a United Launch Alliance Delta 2 rocket successfully hauled the five THEMIS probes into orbit for NASA from Pad 17B at Florida's Cape Canaveral Air Force Station at 6:01 p.m. EST (2301 GMT) [image].

"It was a very smooth count and it was a very good payout after yesterday's tough one," NASA launch director Chuck Dovale said after the space shot [VIDEO animation].

Poor weather prevented preparations for a Thursday THEMIS launch, only to be followed by high upper level winds that thwarted a Friday launch attempt just minutes before the mission's planned liftoff. But wind concerns did not afflict today's spaceflight.

"Upper air winds were not an issue," Dovale said. "The count was very quiet."

THEMIS, short for Time History of Events and Macroscale Interactions During Substorms, marks the most spacecraft ever launched at one time for the space agency, NASA officials said.

The mission's first probe - dubbed Probe A - popped free of its carriage about 73 minutes after launch as planned, with its four counterparts deploying like flower petals about three seconds later [image].

Each about the size of a dishwasher, the five 282-pound (128-kilogram) THEMIS probes [image] are nearly identical and designed to track the origin of powerful geomagnetic substorms within the Earth's magnetic field [VIDEO mission overview].

Substorms occur when charged particles belched from the Sun crash into the Earth's magnetic field, where they are funneled along magnetic field lines to the Earth's North Pole to spur undulating ribbons of multi-colored hues in the aurora borealis, also known as the Northern Lights. Without substorms, auroras would appear as a static sheet of greenish illumination, researchers said.

By pinpointing substorms, researchers hope to develop a better understanding of space weather - such as the high-energy particles produced by the Sun in solar flares - which can interfere with satellite communications and even endanger astronauts flying in Earth orbit. But researchers are still unclear on where substorms originate.

"By tracking those energy releases from one satellite to the other, [THEMIS] will be able to detect for the first time where those releases emanate," Vassilis Angelopoulos, the mission's principal investigator at the University of California, Berkeley's Space Sciences Laboratory overseeing the mission for NASA, said before today's launch. "Really it's an analogous system to what meteorologists use on the ground."

Angelopoulos added that he hopes the THEMIS mission will shed new light on predicting space weather in the future. THEMIS draws its name from the Greek goddess of justice and wisdom.

The $200 million THEMIS mission stems from a partnership between UC Berkeley and NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Built by UC Berkeley and Swales Aerospace, the five THEMIS probes are designed to take up stations in ever-higher orbits ranging between one-sixth and half the distance between the Earth and Moon [image]. Every four days, the probes are expected to align with one another and ground stations on Earth to provide a curtain of sensors to scan for substorm activity for at least two years [image].