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November 2007

Sunrise test flight successful

Balloon reaches 120,000 feet, captures images of Sun, lands safely in Texas

sunrise balloon

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.

sunrise gondola

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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