Saturday, September 19, 2009

You Can Help Find Exo-Earths

From The Planetary Society, a way that laypersons can get involved in the search for terrestrial exoplanets:

FINDS Exo-Earths

A thrilling new hunt for Earth-like planets orbiting distant stars is starting...

The Planetary Society is teaming up with planet hunters Geoff Marcy of the University of California at Berkeley and Debra Fischer of San Francisco State University to help with the quest to find other "Earths," other worlds like our own, elsewhere in our galaxy.

The project is called FINDS Exo-Earths (which stands for Fiber-optic Improved Next generation Doppler Search for Exo-Earths).

This new high-end optical system will be installed on the 3-meter telescope at the Lick Observatory, dramatically increasing discoveries of smaller exoplanets and playing a crucial role in verifying Earth-sized planet candidates from the Kepler planet-hunter mission.

This is exactly the kind of project the Society has always excelled at. It's a small, vital effort, overlooked and under-valued by the space community's "Powers That Be." And we can see that it offers an incredible cost-benefit ratio.

Imagine: a way to specifically hunt for and discover Earth-sized planets orbiting far distant suns. This could truly revolutionize exoplanet exploration. It will, at the very least, massively expand our scientific knowledge; at best, it could eventually prove a major step forward in the dream of finding life native to another world. It will also provide valuable backing to NASA's Kepler mission, a vital goal all in itself.

How Does FINDS Exo-Earths Work?

When planet hunters train their telescopes on the stars, they usually aren't looking for an actual visual image of any planets. The distances are simply too vast. Rather, they seek evidence of those distant planets based on the behavior of the light from the stars themselves.

The most common method is called the "radial velocity technique," which relies on measuring minute Doppler effect changes in the star's light. The starlight changes because orbiting planets "tug" on their stars; so, as they circle, a minute Doppler effect occurs in the starlight. This tug either pulls the light waves slightly apart, or pushes them slightly together, changing their frequency. (It's the same effect that occurs to sound waves when a train rushes by you, with the sound of its whistle suddenly dropping in pitch.)

You can imagine how small these changes are, and how hard to detect. Modern technologies make it possible, but there are limits. For example, the terrific 3-meter telescope at the Lick Observatory can detect Doppler velocities of about 5 meters per second. That's good enough to spot enormous Jupiter-sized planets.

But to identify smaller worlds -- the ones more likely to have life -- a telescope must be able to detect Doppler velocities of 1 meter per second. To detect a planet the size and density of Earth, the precision would have to be under 0.5 meters per second.

The Marcy-Fischer team has tackled this problem by devising not one, but two optical systems to be used in tandem. The first is a fiber optics array that will make the cone of light entering the telescope's spectrometer "uniform," and therefore resilient to naturally occurring changes that foul up Doppler measurements.

The second part is an adaptive optics system that will keep the maximum amount of light flowing through the system -- that is, providing a better "signal-to-noise ratio."

Altogether, this bundle of new technology is referred to as Fiber-optic Improved Next generation Doppler Search for Exo-Earths, or FINDS. At Lick, it could improve detection to the 1-meter range, enabling additional discovery of many Neptune-sized planets and larger. If Marcy-Fischer can do all that with our help, then it will be on to the Keck Telescope, where 0.5 meter precision (and Earth-size planet discoveries) can happen.

And, once our instrument is adapted for the Keck Telescope, FINDS Exo-Earths will provide crucial follow-up for planets found by the Kepler mission. Specifically, the Keck Telescope -- equipped with FINDS -- will rule out false positive detections of Earth-sized worlds.

We're on the brink of discovering Earth-like planets around other stars -- worlds that may support life. You can play a key role in the hunt!
To make a secure tax-deductible donation to the FINDS Exo-Earths project, visit the Project's donation Web page at <https://planetary.org/join/donate/0903exow/>. The Planetary Society's FINDS Exo-Earths Project main Web page is at <http://planetary.org/programs/projects/finds/>.


Reference:

"Projects: FINDS Exo-Earths." What We Do. The Planetary Society. n.d. Web. 19 September 2009. <http://planetary.org/programs/projects/finds/>

Image credit: Ryan Bliss, DigitalBlasphemy

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