November
2007
Sunrise test flight successful
Balloon reaches 120,000 feet, captures images of
Sun, lands safely in Texas
Slender hoses partially fill the
balloon with helium before the launch. |
In the wee hours of the morning on October 3, an international
team of researchers in Fort Sumner, New Mexico, was already
wide awake and full of adrenaline. They had waited several
days for the ideal weather conditions. At about 9:00 a.m.,
after hours of preparation, they successfully launched the
Sunrise balloon on its landmark test flight.
“I still get nervous thinking about the launch and
test flight,” says ESSL/HAO scientist Alice Lecinski. “Watching
the balloon inflate against the morning light, the gossamer-thin
plastic growing, swelling, ready to blast to the stratosphere—it
was so scary. All those years of work and testing by so many
hardworking people.”
The gigantic balloon, big enough to fit a Boeing 747 jet
inside, rose to 120,000 feet. From this altitude, the solar
telescope cradled in a gondola dangling from the bottom
of the balloon was able to capture images of the Sun’s
surface, with other data gathered from various instruments
in the gondola. The balloon flew for 10 hours, at which point
the gondola separated from the balloon and descended by parachute,
landing safely in northern Texas.
“We were able to verify the workings of the entire
system end to end,” says Dave Elmore (HAO), who oversaw
the test flight. “We can now move on
to planning the first full-scale mission with confidence.”
The test flight took place at the Columbia Scientific Balloon
Facility.
In addition to scientists and engineers from HAO and EOL,
the team includes collaborators from research institutions
in Germany, Sweden, and Spain, as well as NASA, the University
of Chicago, and Lockheed Martin Corporation.
Researchers have been working on the Sunrise project for
six years. Their goal is to investigate the structure and
dynamics of the Sun’s magnetic fields. The fields fuel
solar activity, including plasma storms that buffet Earth’s
outer atmosphere and affect sensitive telecommunications
and power systems. The fields also cause variations in solar radiation,
which may be significant factors in long-term changes in
Earth’s climate.
Secure within its gondola, the
telescope hangs suspended from a crane-like launch
vehicle at dawn. |
From an altitude of 120,000 feet, the telescope can capture
images of the Sun’s surface in a higher resolution
than can be obtained from Earth’s surface, including
features on the solar surface as small as 30 kilometers
across (about 19 miles). These images will enable scientists
to examine structures on the Sun that are believed to be
key to understanding the mechanisms driving solar activity.
And by flying at high latitudes during the summer, the
telescope will allow scientists to witness changes in magnetic
fields without the interruption of night.
Because the test flight was intended mainly to show the feasibility
of the balloon platform and navigation system, the gondola
carried a less powerful solar telescope. The next stop is
Kiruna, Sweden, where researchers will launch the actual
Sunrise telescope for a multiday flight over the Arctic
in the summer of 2009. By taking advantage of the midnight
Sun, the telescope will be able to capture continuous
images for a period of several days to as long as two weeks,
possibly orbiting the Arctic.
One advantage of balloon-borne scientific missions is that
they cost less than sending instruments into space. They
also provide a way for scientists to test an instrument before
making a commitment to launch it on a rocket.
“This is a very economical way of rising above the
atmosphere and capturing images that cannot be captured from
Earth,” says HAO director Michael Knölker.
Sunrise has presented EOL’s engineers with a number
of unusual challenges. The balloon is designed to carry 6,000
pounds of scientific equipment that must be able to withstand
dramatic changes in temperature as it rises through the atmosphere.
The steel and aluminum gondola cannot vibrate in ways that
could interfere with the operation of the telescope.
Most challenging, however, is the fact that the telescope
must remain focused on a specific and relatively tiny area
of the Sun, even while twisting on a soaring balloon for
a week or longer during the full-scale research missions.
To accomplish this, engineers designed a torque motor drive
to keep the gondola and telescope in the correct orientation
and a precision guiding and compensation system to constantly
correct the telescope’s aim.
The gondola, which descends via parachute, is designed to
withstand considerable force when it lands, with roll cages
and crush pads protecting the payload so that the instruments
can be launched on repeated missions.
To ensure that the gondola lands in a safe place away from
homes, roads, and other targets, meteorologists use software
to predict its landing with near-perfect accuracy. They are
able to tell researchers exactly when to separate the gondola
from the balloon so that the gondola lands in a safe, remote
spot.
During the test flight, the gondola landed on a family farm
outside Dalhart, Texas. It was quite a surprise for the Nefstead
family, who found it in their wheat fields. When the Sunrise
crew arrived early the next morning to recover the payload,
two TV stations from Amarillo were already on the scene.
As
it happens, Scott Nefstead is a math teacher at the local
high school and involved in the school’s science club.
Michael later tracked the family down via the high school
and invited them on an expenses-paid trip to NCAR. “The
family was very supportive and friendly, so I thought we
should give something back to them,” he says.
The family has plans to come to Boulder in December. They’ll
take
a grand tour of NCAR and get an
especially close look at HAO, meeting the scientists and
engineers who designed the gondola that crashed onto their
land. Michael is also working with EO to prepare outreach
materials for Scott to use in his classroom.•
On
the Web
More
details about the test flight
Images
and video of the launch
In this issue...
IPCC
contributors share in Nobel Peace Prize
Remembering
John Firor and Janet Roberts
Sunrise
test flight successful
Same
library, new home
A
firsthand look at disappearing sea ice
NCAR
launches Women in Science committee
Fantastic
forum
Staff
win awards for science, multicultural service
Just One Look
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