Astrocomb will Significantly Improve the Search for Extraterrestrial Life

The search for Earth-like planets will get a massive boost with the addition of Astrocomb in the planet-hunting telescope.

The researchers from the National Institute of Standards and Technology (NIST) have developed a customized frequency comb that is much more precise than the preceding technology. Astrocomb uses a spectrograph at the Hobby-Eberly Telescope to make precise measurements of colors or frequencies of light. The precision of this comb has enabled the astronomers to discover and characterize planets orbiting M Dwarf Stars. This is a massive achievement because almost 70% of the stars in our galaxy fall into this category and quite a lot of them are close to our planet. Scott Diddams, a Fellow at NIST, praised the brilliance of Astrocomb and said,

“The comb immediately allowed our Penn State colleagues to make measurements they could not otherwise make. These improved tools should allow us to find habitable planets around the most ubiquitous stars in our galaxy.”

Significance of Astrocomb

The nuclear fusion within a star results in the emission of white light, which is then modified by different elements in the atmosphere as they absorb specific bands of colors from it. In order to locate planets around a distant star, scientists try to observe periodic changes in the characteristic colors of starlight (fingerprint) over time. These variations (star wobble) are caused by the gravitational pull of an unseen orbiting planet and the frequency standards of the observing spectrograph play a defining role in determining whether the planet will be located or not.

Despite the fact that thousands of exoplanets have been discovered until now, it is incredibly difficult to detect Earth-sized planets in the Goldilocks Zone (the area around a star where liquid water could exist) of the distant stars with the conventional technology. This urged scientists to develop something more powerful that could detect Earth-mass exoplanets.

In order to find an answer to that, the researchers from the University of Colorado (CU) and Pennsylvania State University collaborated with the experts from NIST. They eventually came up with Astrocomb, a customized spectrograph that has the ability to detect such planets as it causes color shifts equivalent to a star wobble of about 1 meter per second. It is 10 times better than the previous best measurement achieved in the Infrared region of the electromagnetic spectrum.

Astrocomb

The researchers at NIST are continuously improving the optical frequency combs for the last 20 years, after inventing them in first place. Astrocomb is the latest addition to the list. It has 5,000 specific color calibrations points (teeth) and can span the target infrared wavelength band of 800-1300 nm. Having said that, it is only 60×152 square centimeters in size. The use of a relatively simple commercial material and the robust nature of the Astrocomb makes it an ideal candidate to withstand continuous use at a remote site. It has been designed specifically for the Habitable Zone Planet Finder (HPF) spectrograph of Penn State University.  

Astrocomb is made with advanced electro-optic laser technology and acts like an extremely precise ruler while providing tailored light to the spectrograph. It calibrates and tracks exact colors in the fingerprint of a star and detects any periodic variations to identify a planet around the star. Astrocomb provides strong signals at accurately-defined target frequencies that can be conveniently traced to international measurement standards.

The idea of using frequency combs to facilitate planet discovery has received quite a lot of appreciation from around the world but Astrocomb is the only one in operation at near-infrared wavelengths. The researching team performed a test run of the technology in 2012 that showed enough promise to go on with the approach. Researchers worked on stabilizing the demo version and enhanced its light range, before the official launch of the product. Astrocomb finally saw its first light in February 2018 and started its regular operation in May 2018.