BRRISON gondola

Pietro Bernasconi, of The Johns Hopkins University Applied Physics Laboratory, works on the BRRISON gondola at the NASA Columbia Scientific Balloon Facility in Fort Sumner, New Mexico. (Courtesy Johns Hopkins University, Baltimore Sun / September 24, 2013)

Scientists from the Johns Hopkins University Applied Physics Laboratory are set to launch a massive balloon above the skies of New Mexico this weekend for a glimpse of Comet ISON, the rare comet on its way to looping past the sun and Earth in the coming months.

The balloon will be carrying a telescope that will observe ISON, as well as another comet that commonly passes through the solar system, in infrared light to see the water and carbon dioxide emanating from it. The mission was pulled together over the past seven months to gather data on ISON before it passes closely by the sun, potentially destroying the comet.

Scientists are eager to gather that data while they still can because ISON, coming from outside the solar system, is a rare opportunity to see what sorts of materials were left over when stars and planets formed in the early universe.

"It's a great opportunity to study some of the volatile constituents that have been preserved in the deep freeze since the beginning of the solar system," said Andy Cheng, principal investigator for the project, known as Balloon Rapid Response for ISON, or BRRISON.

The launch was originally scheduled for Sunday morning, but because of prime weather forecasts for Saturday evening, it was moved to about 7 p.m. Mountain time Saturday. Any updates on launch changes will be posted at facebook.com/BRRISON.

NASA called on the Hopkins lab to organize a mission in February, meaning it had to pull the project together at lightning speed, so far as space research is concerned. That's largely why the lab was chosen — a balloon mission, sending observational equipment above all but 0.1 percent of the Earth's atmosphere, can be organized in months, while sending the same equipment into space would take three to four years to prepare for.

The mission involves partially inflating a massive teardrop-shaped balloon with helium and allowing it to rise nearly 25 miles above the Earth's surface. As it rises, air pressure changes will make the balloon inflate fully, until it's as wide as a football field and as tall as the Washington Monument in D.C.

After a journey taking several hours, the balloon is expected to hover for about six to eight hours, allowing a cryogenic infrared camera to observe ISON from millions of miles away along with Comet Encke, a comet that contrasts with ISON because it has passed near the sun thousands of times already, Cheng said. Only a handful of comets have been observed in the infrared wavelengths the scientists will be able to see, and detecting differences between ISON and Encke could help explain more about ISON's properties.

Comet ISON has been called a possible "comet of the century" by some because its close passage by the sun could brighten it so much that it becomes visible to the naked eye from Earth this winter. It's also possible the sun's heat will break it up, making it less of a spectacle for laypeople but still of interest to scientists studying the early universe, comets and the sun.

The launch timing hinges on winds at all levels of the atmosphere, because the balloon isn't allowed to drift over heavily populated areas. Forecasts show the balloon could drift toward the Dallas area, so the flight will have to be aborted if it gets too far east.

"It's kind of a scramble right now to readjust everything," Pietro Bernasconi, lead engineer for the balloon's gondola, said Friday. "If this is our opportunity, we will do it."

When the flight ends, the balloon will be popped and the instruments will fall back to Earth by parachute.

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