With Observations in Full Swing, Team Prepares to Remove "Sunglasses" from Telescope
Posted by Amir Alexander
2007/02/26 11:00 CST
Winter time is observing time at the Oak Ridge Observatory in Massachusetts, when humidity is low and the sky is often clear. And so it has been for the Optical SETI telescope, which opened its doors in April 2006. This is the first winter of observations for the telescope, and Paul Horowitz and his team have been very busy. After a period spent testing and bringing its systems to working order, the telescope began scanning the skies more regularly last fall. Taking advantage of every clear night, the Optical SETI telescope has now covered nearly half of the northern skies in its search for that telltale flash of light from the stars.
Covering so much of the sky in such a short span of time is a testament to just how much things have changed at the Optical SETI observatory in its ten months of operation. The early sets of observations were conducted manually from the observatory building itself. It was hard work and slow going, but it was necessary in order to test the telescope and establish its capabilities. Over the summer Horowitz, Postdoctoral fellow Andrew Howard, graduate students Curtis Mead and Jason Gallicchio, and undergraduate Steve Howard put in place the computerized controls that allow them to remotely control all the operations of the telescope.
These days, explained Mead, it can take as little 5 minutes on line to program a full night’s observations from the comfort of the SETI lab on the Harvard campus. In practice, though, Mead and his colleagues don’t settle for this bare minimum, but monitor the operations for around 30 minutes. They check with their web-based weather service to make sure that conditions are suitable for observations, and they view the image from the digital night-sky camera that is located at the observatory. If the skies are overly cloudy, or if conditions risk damage to the telescope, no observations will take place. But on most nights the team gives the go ahead for the observations to begin, and continue through the night. They stay around for the first few minutes to make sure that the roof had opened properly and then watch as the initial data starts streaming in. That is all. The telescope will continue observing on its own and shut down automatically as morning comes. When Team members return to the lab in the morning, the results of the night’s observations will be waiting for them.
If this isn’t simple enough, Horowitz’s team have plans to make things easier still. This summer they hope to install more sophisticated software to control the telescope, which will automatically adjust its bearings every night, taking into account weather and visibility conditions. According to Mead, it should then be possible to program the telescope just once a month. The telescope will then follow its plan of observations without need for human intervention.
When funding from The Planetary Society comes through, Horowitz’s team are also planning to replace the “pixel amplifiers” in the telescope’s camera, increasing the telescope overall sensitivity five times over. The pixel amplifiers take the signal received by the camera’s 1024 photo multiplier tube (PMT) pixels and amplifies them, before passing them on to be analyzed for the presence of light signals. Up to this point, explained Mead, the telescope was operating with an older set of amplifiers, which the team originally tried to replace even before the telescope was inaugurated last April. When the replacement amplifiers did not perform as hoped, they fixed up the old amplifiers and have used them ever since. In effect, said Mead, “up to this point we have been running the telescope with sun-glasses on.”
With funding from the Planetary Society, these glasses could be coming off soon. Howard and Mead are currently working on new amplifiers that could revolutionize the telescope’s capabilities. Instead of detecting signals with a minimum strength of 100 photons per square meter, the newly equipped telescope will be able to detect signals only one fifth as strong � 20 photons per square meter. This means that the telescope will now be able to detect a signal five times weaker than before, from up to 12 times as many of stars. A weak or distant alien signal, which would have been overlooked with the old amplifiers, could now come through bright and clear.
The search for that brief flash of light from the sky that will tell us we are not alone in the universe continues unabated at the Oak Ridge Observatory on a quiet Massachusetts hilltop. Almost every night the telescope points giant mirror upwards, and scans another patch of starry skies. But not tonight. “It's cloudy with 100% chance of rain" explained Mead. The search for an alien civilization will wait for another night.