December 6, 2017

WIDE-EYED: ESPRESSO Planet Hunter Ready to Drink in the Universe for Alien Worlds.

The ESPRESSO instrument, which is installed on the European Southern Observatory’s Very Large Telescope (VLT) in northern Chile, made its first observations last month, project team members announced today (Dec. 6).

ESPRESSO is designed to find alien planets via the “radial velocity” method — that is, by detecting the tiny wobbles in a star’s movement caused by the gravitational tug of orbiting planets. The instrument is the next-generation version of the prolific HARPS spectrograph, which has discovered more than 100 exoplanets to date.

Only NASA’s famous Kepler space telescope, which looks for the tiny brightness dips caused when planets cross their star’s face, has found more alien worlds than HARPS. (The gap between the two is pretty big, however: Kepler’s tally currently stands at 2,515 planets across its two missions, along with 2,500 or so additional “candidates” awaiting confirmation by follow-up studies or observations.)

“ESPRESSO isn’t just the evolution of our previous instruments like HARPS, but it will be transformational, with its higher resolution and higher precision,” project lead scientist Francesco Pepe, of the University of Geneva in Switzerland, said in a statement.

Just how precise will ESPRESSO (whose name is short for Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations) actually be? Project team members are aiming for a velocity-measurement precision of just a few centimeters (1 inch or so) per second, compared with the 1 meter (3.3. feet) per second capability of HARPS. ESPRESSO should therefore be able to spot some of the smallest planets ever found, ESO representatives said.

Most of the exoplanets I can recall have had too much mass to really be earthlike. ESPRESSO should help find ones closer in size to Earth.