Robotic Telescope Captures Clear Images of Exoplanet Stars

Photo: Christoph Baranec

This story was corrected on 12 August 2014.

From earth, a robotic telescope, called Robo-AO, can now snap high resolution images of stars near exoplanets and automatically set itself up to research hundreds of new targets each night. Although adaptive optics is an established technique, an international team of researchers says that Robo-OA is the world’s first fully autonomous laser adaptive optics and imaging system. The benefit: Robo-AO, which is attached to a 1.5-meter telescope, can study thousands of exoplanet systems in record setting time.

The utility of most ground-based telescopes is limited because of the blurring effects caused by turbulence in the earth’s atmosphere. But, Robo-AO accounts for this turbulence, allowing it to capture images rivaling the resolution of those captured by the Hubble Space Telescope.  

Researchers designed the system, at a cost of roughly $1 million, so that it can be applied to any 1-meter-to-3-meter-class telescope. Details about the design and operation of the instrument were recently published in the Astrophysical Journal

“Ultimately we see that this is the kind of system that can end up on every telescope of this size around the planet,” says Nicholas Law, assistant professor at the University of North Carolina. According to Law, there are a few hundred of these 1-to-3-meter-class telescopes scattered across the globe.

Although laser adaptive optics systems have been around for the past 15 years, their ability to lock onto a target is still relatively slow. It still takes about 10 minutes to lock on to each new target, which might not sound that long, but if you’re studying thousands of targets, it adds up. Robo-AO is the first instrument to fully automate this tedious process, cutting the time down to about 1 minute. 

“That’s really new; no one has been able to do that before,” Law says. So, instead of only targeting tens of exoplanet systems per night, now, telescopes can target hundreds of them.

Speedy targeting times are one thing, but to capture clear images, researchers had to remove image blurring due to turbulence in the earth’s atmosphere. This two-step process started with researchers firing a laser into the atmosphere to measure how the earth’s turbulence affects the images captured. Then, they took the starlight that entered the telescope and bounced it off a tiny micro-electromechanical deformable mirror. Using the previous laser measurements as a benchmark, they deformed the surface of the mirror so that it cancelled out the effects of the turbulence.

“In doing so, we end up with starlight as if it hasn’t gone through any turbulence at all,” Law says. 

This collaborative effort between researchers at the University of North Carolina, the University of Hawaii at Manoa’s Institue for Astronomy, and Caltech started around five years ago. Law says that the biggest design challenge was developing “reliable and robust software so that the robot would keep operating and control the many feedback loops.”

Now that all the software kinks are smoothed out, Robo-AO is undertaking a huge variety of science research, including surveying 4,000 potential exoplanet systems discovered by Kepler to validate if their are indeed planets there or not. It’s also occasionally studying asteroids, comets, moons, and planets in our solar system. According to Law, they have already observed more than 12,000 stars, and they’re currently searching for funding to set up a second Robo-AO system.

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