Detector technology could help NASA find Earth-like exoplanets

July 22, 2010

The hunt is on for Earth-like planets outside of our solar system. Since the 1990s, astronomers have detected more than 450 extrasolar planets -- mostly large Jupiter-sized bodies -- around nearby stars. Advances in technology are fueling the quest to find smaller, rocky planets resembling Earth and, possibly, evidence of life.

Rochester Institute of Technology scientist Don Figer is developing detector technology funded by NASA's Technology Development for Exoplanet Missions Program and designed to directly image and characterize exoplanets. The two-year funded project will result in a detector array that can withstand the radiation in space, count individual photons or light pulses—thereby eliminating noise that could obscure the faint signal -- and characterize exoplanets in one-third the time it takes using existing methods.

"If you can detect something much more quickly you can search many more systems," says Figer, director of the Rochester Imaging Detector Laboratory and professor in the College of Science at RIT. "A three-year mission becomes a one-year mission, or you can detect three times as many objects in the same fixed time. That's usually what astronomers like to do."

To accomplish this "super" detector, Figer and his colleagues at Massachusetts Institute of Technology Lincoln Laboratory are adapting technology they are currently developing for ground-based applications, such as the Thirty Meter . That project, funded by the Moore Foundation, supports the development of optical and infrared megapixel zero-read-noise detectors. Both initiatives build on detector technology originally invented at Lincoln Laboratory.

The primary work at RIT for the NASA Technology Development for Exoplanet Missions Program will focus on radiation testing. Figer's team is building the system to gauge the detector's performance in the high-energy radiation environment of space. Scientists at Lincoln Laboratory are fabricating the 256 by 256 pixel array. Each pixel will be 25 by 25 microns; each detector will span 1/4 by 1/4 inch.

"The goal in an exoplanet search depends on the question one wants to answer," Figer says. "If you want to characterize planetary systems around other stars then you probably need to detect the full mass spectrum of exoplanets. Right now, they're only discovering the big ones. If you think the real goal is to detect life, you might want to find smaller planets more like the size of the Earth."

Since the 1990s, large, gaseous exoplanets have been discovered using the Doppler shift method. Scientists using this approach measure the changing line-of-sight velocity of a nearby star and infer the planet's characteristics from the amplitude and frequency of those variations. In contrast, the coronagraphic technique images an exoplanet by blocking the starlight. Occultation, another method in exoplanet research, uses the planet itself to block light from the star, extracting information from the attenuation of light during the eclipse.

"One of the potentially most dramatic applications of zero-read noise technology might be in the occultation application because you're required to make quick measurements at very fine time intervals," Figer says. "But when you make quick measurements with detectors the noise is higher. For a detector that doesn't have read noise but detects individual photons, the noise would be zero regardless of how fast it is reading out."

"I think, if it's successful, it will pervade many applications in many fields," Figer adds. "In particular, for space astrophysics it would become a new standard."

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3 / 5 (3) Jul 22, 2010
I think the biggest slap in the face is that even if we had a "magic" sensor that could tell us that there was an Earth-like planet WITH life on it, we could never get there. Well, at least not quickly. Our current space travel technology brings to mind the image of a lone shipwreck survivor on a small island with a single palm on it. We're trapped, surrounded by empty vastness.
4 / 5 (2) Jul 23, 2010
Even without possibility of visitation or communication with extra-solar life, the mere fact that we can confirm that there is life out there would be an epochal moment in the history of our planet. Discovering that there is intelligent life would be another (but perhaps slightly less of an impact than finding extra-solar life itself).

At that moment of discovery, the universe would blossom from largely being seen as a sterile lifeless environment to one which has life from corner to corner. Certainly many believe this to be the case now, but this is based on faith, hope and conjecture, no hard evidence.

Once the evidence definitively sides with the living universe, there are nigh-infinite possibilities for that life. There's no longer a rational argument against extra-solar intelligences, or civilizations, or simply beings or habitats of unimaginable diversity and wonder.
not rated yet Jul 23, 2010
To use your analogy, it's not the case of a lone shipwreck survivor. It's more like the case where that island inhabitant thinks he's the one and only human on the planet. A sad state of affairs to be sure. However, just the merest sign that there are others alive out there, perhaps even a thriving civilization, would be incredible.

Being cut-off from other life isn't depressing to me. Rather, being alone in the universe would be crushingly depressing not to mention mind-bogglingly frightening that we may squander our life. Knowing that there is life out there, knowing that we are not alone, knowing that life will continue and thrive long after our civilization, our planet, our star is gone (whether that be a long or short time due to our actions or not), would give me a great sense of security, even if we never got to visit or talk to our neighbours.
not rated yet Jul 26, 2010
I feel you temple but I am with trek, this is relatively a waste. What is the point if we cant get there? Will we try to communicate or what?

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