UA watching out for asteroids headed our way

Top: Peering through its open dome, the Schmidt Telescope is ready for another night of searching for asteroids. (Photo: Catalina Sky Survey)
Bottom: The Schmidt Telescope located on Mt. Bigelow in the Catalina Mountains just north of Tucson, Ariz. is one of the instruments used to detect asteroids that could pose a hazard to Earth. (Photo: Catalina Sky Survey)

By University of Arizona Communications

March 6, 2012 - NASA is awarding $4.1 million to the Catalina Sky Survey to upgrade its search capabilities for near-Earth objects - asteroids that might cross the Earth's path someday.

The Catalina Sky Survey, or CSS, a UA-based program that searches for hazardous asteroids that might pose a collision threat to the Earth, will receive a new NASA grant totaling more than $4.1 million to upgrade and operate its telescopes through 2015.

The CSS program, part of the UA's Lunar and Planetary Laboratory, has led the search for so-called near-Earth objects, or NEOs, since 2005. CSS consists of two wide-field survey telescopes and a dedicated follow-up telescope located in the Catalina mountains north of Tucson, Ariz.

In 2011 the CSS science team discovered 586 near-Earth asteroids, representing 65 percent of NEO discoveries for the year. In addition to its record-setting searches for asteroids, the team was the first to observe an asteroid on a collision course with the Earth, allowing it to be tracked and eventually recovered as meteorites in the desert of Northern Sudan.

Their large and growing data set has also found new relevance in the search for objects far beyond the solar system. With their new grant, CSS astronomers will be able to expand the power of their largest telescope four-fold, develop more sensitive software, and conduct their search more nights every month.

"NASA has recognized that over the last seven years, our program has constantly strived to improve its performance, and has collaborated with others to find new ways to exploit the nearly 1,000 images we take every night with our two telescopes in the mountains north of Tucson," said Edward Beshore, principal investigator of the Catalina Sky Survey. "I think NASA recognizes the CSS as a valuable service to, well, humanity."

To spot NEOs, CSS observers use two telescopes to take four images of selected portions of the sky, spaced about 10 minutes apart. Software then processes the images, looking for faint objects that appear to be moving across the sky in a straight line.

Specialized software then removes known asteroids, applies filters to remove false detections and presents the results to the observer for final validation. Asteroids suspected of qualifying as NEOs are reported to the Smithsonian Institution for analysis and follow-up images are scheduled.

It takes several hours of such observations to reveal whether an object is a NEO. Finally, objects whose orbits intersect with the Earth's are called out for additional study by amateur and professional astronomers around the world.

A key element of the new grant, a more powerful camera will allow the project to cover more sky with the 1.5-meter telescope on the summit of Mt. Lemmon.

CSS co-investigator Steve Larson, who designed the new camera, said: "When we began observing in 2000, our image sensor was 16 megapixels, which was large by any standard. Today, commonly available consumer digital cameras have surpassed that size, and we were reaching the limit of productivity with our current camera design."

A few years ago, Spectral Instruments, a local vendor of scientific imaging systems, presented a sensor totaling 110 megapixels. Together with Tucson-based optical designer Richard Buchroeder, Larson developed a powerful new camera system that would increase the amount of sky it can cover each month by four times.

"We believe this will translate into a nearly proportional increase in the number of discoveries we make each month," Larson said.

The grant will facilitate other enhancements too, such as support additional software development to improve the speed and sensitivity of the CSS software, and the addition of a new observer that will allow them to work more nights each month.

"This grant represents a nice boost for the local economy, with almost 100 percent of our funds being spent right here in Tucson," Beshore said.

The CSS program is not limited to the search for asteroids. A spinoff project called the Catalina Realtime Transient Survey makes further use of the data acquired for the asteroid survey.

"We image the entire sky every month with our telescope on Mt. Bigelow," Beshore said, "in partnership with colleagues at Caltech who had developed software to search for changes in the stationary cosmic objects. Almost as fast as we can acquire the data, they are able to detect changes in the brightness of stars and galaxies that can reveal important clues about objects millions of times farther away than the asteroids we search for."

In 2010, Beshore's team discovered more supernovae, stars that end their lives in a violent explosion, than other programs specifically designed for just that task. More recently, CSS and Caltech announced the web publication of data documenting the brightness history of nearly 200 million objects with more than 20 billion independent observations, a catalog 10 times larger than anything previously published.

"We were thrilled to get the news from NASA about our grant," Beshore said. "At the same time, we regularly remind ourselves that we have an important responsibility to all those who support our work with their tax dollars."

"Aside from helping to ensure that we don't get blindsided by an asteroid, we owe the public the most efficient use of our funding, and we are grateful that we have once again been given the chance to show the world what we can do."