In 2006, a new telescope was launched at Oak Hill Observatory to search for extraterrestrial intelligence. (Photo by Lisa Aciukewicz)

Oak Ridge Observatory has been scanning the skies above Harvard for more than 75 years. Once a center for tracking minor planets and gas clouds, it now searches outer space for signs of intelligence.

Harvard University established the 40-acre site off Pinnacle Road in 1932 to station a giant telescope known as the Wyeth reflector. Housed in a three-story brick building, it used a five-foot wide mirror to track objects in space with great precision.

Also at the site was an 84-foot radio dish. Made to watch movements of the massive hydrogen clouds that clutter the universe, it was later converted to search for radio waves from extraterrestrials. This search is now performed with dedicated optics, looking for lasers sent by aliens.

Astronomers discovered 39 minor planets from Oak Ridge, one named for the observatory itself, ORO, and another for guitar legend Eric Clapton. But the greatest achievement occurred in 1988, when Harvard resident David Latham discovered the first planet ever detected outside our solar system.

Oak Ridge has been popular with students, who were thrilled to come out on a clear night, open the dome, and gaze at the stars. The location benefited the university as well. As Latham, a senior lecturer on astronomy said, “We were able to involve Harvard students in research projects, taking advantage of the fact that Oak Ridge Observatory was nearby.”

Harvard physics professor Paul Horowitz started using the 84-foot radio telescope in 1983 to ‘listen’ for aliens. This system, called Megachannel Extra Terrestrial Assay was supported by a $100,000 grant from Stephen Spielberg, who was promoting his new movie, ET, at the time. It was upgraded 12 years later to Billion-channel Extra Terrestrial Assay, which ran until 1999 when the dish was damaged in a windstorm. It was dismantled in May 2007.

Undaunted, Horowitz switched to the nearby Wyeth telescope and began Optical Search for Extra Terrestrial Intelligence (OSETI). This time, instead of radio waves he was looking for lasers.

Astronomers were already using the Wyeth to locate planets outside our solar system, so Horowitz piggybacked his experiments onto theirs, gathering data from whatever star the telescope was pointing at. After viewing 5,000 sun-like stars, the Wyeth was shut down in 2005, due to lack of funding.

The following year, Horowitz and a team of graduate students built their own telescope. Using a custom chip called PulseNet, the system processes 3.5 billion bytes of data per second, comparable to scanning all the books in the world—every second. With this kind of processing, the telescope didn’t need precision optics and could be small and inexpensive. It sits in a building the size of a one-car garage and cost less than $400,000.

The team rarely needs to leave Cambridge because the telescope logs data on a website and has an automatic retractable roof with rain sensor. They do need to install a webcam, though, to determine when the rain sensor has snow on it. When the snow melts, the sensor thinks it’s raining and closes the roof.

Horowitz is excited about the new technique because he can scan the whole sky in only 200 clear nights. He said in a telephone interview that, compared to this, “Previous methods were like looking through a soda straw.”

The latest scans and current position of the telescope are posted at www.planetary.org/special/oseti_telescope/.

No aliens have contacted him yet, but Horowitz continues searching because he likes fields that are wide open.

“OSETI is the coolest experiment going,” he said, “and nobody’s doing it.”

For projects like OSETI, fast but small number-crunchers have superseded precision optics and giant data collectors. So the open spaces of Oak Ridge have become underutilized and potentially unnecessary. But whatever happens at Oak Ridge, the people who worked there have created a lasting legacy for Harvard and the skies above.