Five NASA probes
aimed at unraveling mysteries surrounding Earth's colorful auroras are set to launch Friday
evening after a 24-hour weather delay.
VIDEO:
Aurora - Dangerous Beauty
A United Launch
Alliance Delta 2 rocket carrying the five
probes that make up the Time History of Events and Macroscale Interactions
During Substorms (THEMIS)
mission is scheduled to liftoff between 6:05 and 6:23 p.m. EST on Feb. 16 from
Pad 17-B at Kennedy Space Center (KSC) in Florida. The launch will set a new
NASA record for the most number of scientific satellites ever launched into
orbit aboard a single rocket. [VIDEO: THEMIS launch animation.]
"We're
complete through all of our readiness reviews," KSC launch director Chuck Dovale
told reporters Thursday during a press conference. "The team is poised to start
countdown tomorrow and we're ready to go."
The probes
were originally set to launch on Thursday, Feb. 15, but thunderstorms and severe
weather in the Cape Canaveral region the day before interrupted fueling of the rocket.
Weather
forecasters are optimistic that winds tonight will not reach beyond about 29
mph (25 knots), which is the minimum requirement for a launch abort.
"I am looking
at a 20 percent 'no go' for tomorrow's launch based on wind," said Air Force weather
officer Joel Tumbiolo. "That's 80 percent 'go.' That's a pretty good chance
right there."
THEMIS
consists of five identical probes [image],
each about the size of a dishwasher and weighing nearly 300 pounds, that will
spread out to form a unique constellation aimed at studying the aurora
borealis and aurora
australis--the colorful light shows that occur over Earth's northern and
southern polar regions, respectively.
Undulating
like rainbow ribbons in the sky, auroras are visible manifestations of
so-called "geomagnetic substorms" that occur in near-Earth space. These substorms
are caused when electrically charged gas blown by the Sun's solar winds slam against Earth's magnetic shied, called the magnetosphere.
THEMIS will
help answer scientific questions about when and where the substorms start, but
it could also have practical implications, said Dick Fisher, director of NASA's
Helios Division. For example, Fisher said, airlines currently require pilots
flying over the North Pole to maintain constant communications. If
communications is broken, as can occur during substorms, pilots are required to
land their planes. Being able to predict when substorms might occur could thus
help airlines better plan their routes. [VIDEO: THEMIS mission overview.]
"To get a
jetliner on the ground and make it stay overnight costs a lot of money," Fisher
said.
When they
begin data collection next winter, the five THEMIS probes [image]
will align over North America once every four days [image],
allowing 20 ground stations in Canada and Alaska to monitor substorms for 15 to
20 hours at a stretch. Over the mission's two-year lifetime, the probes are
expected to observe some 30 substorms.
"We're
looking forward to the next challenge," aid UC Berkley's Peter Harvey, NASA's
THEMIS project manager, "which is synchronizing all five spacecraft over North
America and keeping them humming along."
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