Using Laser Combs to Find Exoplanets

We’ve run a couple of articles recently about new techniques to find Earth-like extra-solar planets. Here’s one more, but this new technique is really quite exciting. A new device, called a laser comb, uses femto-second (one millionth of one billionth of a second) pulses of laser light coupled with an atomic clock to provide a precise standard for measuring wavelengths of light. Also known as an “astro-comb,” these devices should give astronomers the ability to use the Doppler shift method with incredible precision to measure spectral lines of starlight up to 60 times greater than any current high-tech method, according to a new paper in the journal Nature.

Astronomers have been using the Doppler shift method to find exoplanets for the past 10 years. Current technology can measure spectral lines with a precision of 60 centimeters per second, which works good enough to find a planet 5 times the mass of Earth in a Mercury-like orbit around a Sun-like star. To find an Earth-mass planet in an Earth-like orbit, a precision of less than 5 cm per second is necessary, and the researchers believe they ultimately can achieve 1 cm per second precision.

The combs work by creating regular spikes of laser light that are evenly spaced in wavelength ”like the teeth of a comb” and can be projected onto a spectrograph.

One of the authors of the paper, Ronald Walsworth from the Harvard-Smithsonian Center for Astrophysics said the group should begin testing its prototype system in June 2008 at the Multi-Mirror Telescope (MMT) Observatory on Mount Hopkins in Arizona. And in 2009 the researchers plan to set up a planet-spotting system at the 4.2-metre William Herschel Telescope on La Palma, in the Canary Islands, in collaboration with the Geneva Observatory.

The inventors of the laser comb, John L. Hall and Theodor W. Hansch shared half of the 2005 Nobel Prize in Physics. This technology has previously been used in chemical sensing and telecommunications. If used with larger telescopes, researchers believe the astro comb could possibly make direct measurements of dark energy.

Original News Sources: Nature, and Nature News

14 Replies to “Using Laser Combs to Find Exoplanets”

  1. It seems the number of ways to find Earth-like planets are starting to crop-up as fast as the planets being found. Before long, an Earth-like will be found.

    I give it 5 years TOPS. 🙂

  2. Perhaps they should look for extrasolar-plant global warming.

    Some people seem to have no problem spotting THAT.


  3. When Earth-like and potentially habitable planets are found, cults aren’t the only thing that will spring up in reaction. Expect jihads in all directions by those who do not believe that God made a universe bigger than a light-year across or older than 7,000 years of age. The followers of such religions experience egregiously extreme cognitive dissonance every time some new scientific discovery is announced that clashes with their bliefs. You can bet a “new Earth” or ten out there won’t just clash with their beliefs, but blow them completely out of the water. The usual response of such people to anything that does that to them is to go on the warpath.

  4. Why are we looking for other Earths? Isn’t the whole point of exploring space to find NEW and DIFFERENT places? Why even bother looking into the Universe if all we want is us?

    I want to find a jellyfish like alien floating in a sea of liquid ethane deep within a gas giant planet created by – NO, I want to find some plasmoid beings at the center of a sun!

    Humanoid aliens who act like us is SO Star Trek.

    Get an imagination, people!

  5. Amazing technology. Being able to detect the relative radial velocity of a star trillions upon trillions upon trillions of kilometres away to an accuracy of 1 cm.s^-1 is simply mind-boggling – here come the Earth-class planet detections!

    And, as an aside, the associated hysteria that will no doubt go along with such a detection among the delusional… I wonder how many different cults will start up as a direct result of a detection of a potentially habitable Earth-like planet?

  6. Excellent. Find a place for humaity to go and inevitably somebody will try to go there. Finding Earth like planets will be a sobering event for humanity and may help spur new interest in space and new generations of humans with space travel and exploration foremost in their imagination.

  7. Korak, the chances of the same series of events to bring about humanoid aliens, or humans just like us, on another planet is so small you can pretty much ignore it entirely. Earth-like worlds are what we look for because we know that life can form on them. It’s already happened on at least one Earth-like world! There is no reason sapient jelly-fish like creatures couldn’t arise in the seas of some Earth-like world out there.

  8. Much ado about earthlike planets,Goldilock planet.Ideas raied for commercial interest of NASA.

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  10. i’ve read the space mirror site. How true is that? 1 sun only in the entire universe?

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