November 16, 2006

Mapping the universe with open source software

Author: Lisa Hoover

Astronomers at New York City's Hayden Planetarium and Rose Center for Earth and Space think space exploration should be easily accessible to anyone. To make that possible, they offer an interactive atlas of the universe that anyone can download for free.

The project, funded by NASA, originally began in 1998 as the Digital Galaxy Project, and was intended to create an accurate, interactive, 3-D representation of the Milky Way galaxy. In 2000, Hayden's Department of Astrophysics decided to expand the project and rename it Digital Universe to reflect its new goal to map the rest of the known universe. They discovered, however, that the software they had developed was not open source, and the resulting restrictions prevented them from adding the additional capabilities they needed to continue their project. To complicate matters, because the software ran on an SGI supercomputer, it was virtually inaccessible.

Fortunately, Stuart Levy, a developer for the National Center for Supercomputing Applications (NCSA), had created an open source tool named Partiview that he used to explore large data sets on his laptop. Developers at Hayden needed a tool that would interpret the large collection of data on the universe and regurgitate it as useful and comprehensible information. Partiview was a perfect fit for their needs. In April 2002, developers at Hayden began offering Digital Universe and the Partiview viewing tool for free download on their Web site. According to Brian Abbott, manager of Digital Universe at Hayden, "since that time, we have had over 100,000 downloads of the Digital Universe atlas, Partiview, and other data products combined."

Partiview is licensed under the Illinois Open Source License, which has been officially certified by the OSI. The Digital Universe license, while not open source, allows users to freely download and distribute verbatim copies of the Atlas, as well as add data and alter existing data. "It is free to those who wish to use it on a PC, for personal or educational use," says Abbott. "But we have retained some control over the data sets to maintain their quality. A curatorial process is necessary to maintain our standards for accuracy."

Although a commercial version of Digital Universe is available through companies that market products directly to planetariums and facilities that provide entertainment along with their education, Abbott says Hayden offers the free downloads because it receives money from NASA, which mandates that publicly funded research be publicly available. "We also lean philosophically toward the idea that the experience of exploring the universe should be available to everyone."

Though the commercial version is typically used in planetariums because the online version is not suitable for today's high-tech domes and digital projection systems, the free version is widely used by educators in a variety of settings, including middle and high schools, museums, and universities. According to a recent survey of users, approximately one-third use the software in an educational setting, but Abbott says Digital Universe is ideal for people who pursue astronomy as a hobby or are doing small research projects with commercially available telescopes.

More open source astronomy
Partiview and Digital Universe aren't the only ways Earthbound astronomy aficionados can track the skies from their computers. We profiled Virtual Moon Atlas, Stellarium, and Celestia in an earlier article.

Bob Lambert uses the software for student and adult education programs at the John J. McCarthy Observatory in New Milford, Conn., and proclaims it to be "dazzling. Our usage is primarily for 'introduction to the universe' awareness sessions and tours, because Partiview and Digital Universe offer such exciting visualization opportunities. No other tools come close to them for navigating the heavens. These tours do more to excite, amaze, educate, and entertain than anything else we do. On a formal basis, we use these tools integrally with the fifth and sixth grade and high school curricula to support teachers."

Educators at the Observatory had been using various planetarium simulator tools for many years, but realized they needed a more capable visualization tool. Their primary criterion was that it work "out of the box" without a lot of adjustments and tweaks. Lambert says they leaned toward an open source solution for its staying power and ability to be easily updated and upgraded as needed. After reviewing several prepackaged options, they decided that Partiview and Digital Universe would meet their needs.

"Partiview is in a class by itself with the dynamics and flexibility, and 3-D mode, which we may be using more than anyone else. The stunning visualization, easy control, superb navigation capability, and 'real data in the proper location in space' is an extraordinary combination," says Lambert. "We do still use other packages ... but Partiview/Digital Universe is the 'big gun' in our excellent arsenal [and] I am sure it will remain that way for a long time."


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