Saturday, December 24, 2016

University of Arizona telescope takes South Pole balloon ride

A University of Arizona team has successfully launched an observatory with a NASA high-altitude balloon from Antarctica.
A team led by UA astronomer Christopher Walker lofted the Stratospheric Terahertz Observatory from the Ross ice shelf near McMurdo Scientific Station on Dec. 8.
During its two-week flight, it will observe the composition and movement of the Milky Way’s interstellar medium — the gas and dust between the stars, which Walker calls “the raw material from which all stars, planets and people are made.”
Walker said he felt as if this year’s ideal conditions for launch were “nature’s way of paying us back” for last year, when the mission was put on hold after he and his team spent 100 days in Antarctica preparing for it.
This year, the team’s 2-ton gondola took flight on the first available opportunity. A previous successful launch of the first version of the instrument in 2012 took nine tries, Walker said.
The observatory is circling the South Pole at an altitude of 127,000 feet, placing it above most of the water vapor in the Earth’s atmosphere.
That location is critical for terahertz astronomy, which explores the millimeter and submillimeter wavelengths of light between infrared and microwaves. That radiation is absorbed by water vapor and difficult to impossible to measure through the atmosphere.
The UA observatory was the third and final successful launch this season, NASA said in a news release.
“This has been the earliest in an Antarctica campaign that all the planned missions were successfully launched,” said Gabe Garde, NASA project manager.
The Antarctic summer is an ideal time to launch balloons. Winds in the stratosphere push the balloons in a circle, allowing for longer flights. The 24-hour sunlight provides maximum energy for solar-powered instruments.
Walker said the telescope is doing a big circle around Antarctica near the South Pole. “It has finished its commissioning phase. We have some nice spectra and things are all working.”
Walker, who arrived back in Tucson this week, said the observatory is operated 24 hours a day from Antarctica and from several sites in the United States, including the Applied Physics Lab at Johns Hopkins University, the Harvard Smithsonian Center for Astrophysics, Arizona State University and the UA, where the effort is being led by Craig Kulesa, Walker’s co-principal investigator. “I don’t think Craig has slept since this thing launched,” Walker said.
This is the second version of the Stratospheric Terahertz Observatory. Scientists at Steward Observatory’s lab built a new gondola, and upgraded the pointing system and the cooling system, Walker said.
The guts of the instrument, which parachuted down after the initial flight in 2012, are the same and they are a mix of parts originally fashioned for other purposes.
The 85-centimeter telescope was originally built for the “Star Wars” program during the Reagan administration but never deployed. It also has parts that were originally built for the NASA’s Spitzer and Herschel space telescopes, he said.
The observatory records emission lines from oxygen and from ionized carbon and nitrogen atoms in the Milky Way galaxy at radio frequencies. “Every atom is a little tiny radio station,” said Walker.
Walker said balloons are the preferred launch platforms for missions such as his. The observatory is too heavy to be launched into space. “The cost is one-twentieth that of a scientific mission in space, and then you get it back,” he said.
That allows scientists to install the latest technology and test it and improve upon it, he said.
In a sense, this launch is a prototype for a more ambitious program to build a terahertz observatory “from scratch.” The team is a finalist for a NASA Explorer mission that will be chosen next year.
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