Objective Prism Extraterrestrial Laser Search

“It would be appropriate to examine high-resolution stellar spectra for lines which are unusually narrow, at peculiar frequencies or varying in intensity.”

– R.Schwartz and C.Townes 1961, Nature, 190, pg.205.

“Lasers can increase your data rate from Mars by 10 times over what you get from radio.”

– Suzanne Dodd,

JPL Director of Interplanetary Network Directorate

“One great advantage of optical SETI is that there’s no terrestrial interference.”

– Frank Drake.

“Optical Inter-Satellite Links are the essential building block for next generation commercial and government space networks.”

– Bulent Altan, CEO Mynaric

Searches for Laser Signals

We perform surveys for laser emission coming from Earth orbit, the Solar System, and from regions of the Milky Way Galaxy.  Targets include the Milky Way Center, its anti-Center, and its Plane. We also target Lagrange points of our Solar system, nearby stars, and and the focal points of our Solar gravitational lens for nearby stars, including Alpha Centauri, Proxima Centauri and tau Ceti.
Space Laser Awareness uses novel techniques to search for extraterrestrial optical laser emission. We employ a Schmidt telescope, an objective prism and a low-noise high speed camera.  The array detectors operate at 4 frames per second, and have 90% peak quantum efficiency, capturing spectra of wavelengths, 380-1000 nm. This system produces a spectrum of every point in the sky within a field of view over 2 degrees across.
Monochromatic light from a laser produces a “dot” in the images, easily distinguishable from the continuous spectra produced by asteroids, planets, stars, galaxies, Cherenkov radiation, and sunlight glints off satellites.
Simultaneously, we operate a second objective prism telescope that gives confirmation of laser pulses.  False positives are rejected.Below are examples of images taken as part of our search for laser pulses from beyond Earth.
The Pleiades star cluster observed with the SLA objective prism telescope system. Each horizontal streak is the spectrum of a star, including wavelengths 360nm to 1000 nm (left to right; blue to red). Laser emission would appear as a “dot” of one wavelength,  validated by appearing in both telescopes at the same point in the sky and the same instant of time within 0.25 seconds.
Video clip of real-time acquisition of objective prism spectra from both telescopes simultaneously, at four frames per second. Field of view is 2deg x 2deg. Laser pulses would appear as a “dot” from both telescopes simultaneously.
Video clip of real-time acquisition of objective prism spectra from both telescopes simultaneously, at four frames per second. Field of view is 2deg x 2deg. Laser pulses would appear as a “dot” from both telescopes simultaneously.
Space Laser Awareness technology can detect, track, and obtain spectra of satellites in real time.
Satellites passing within the field of view are detected instantly by their motion. The direction and angular speed of their motion are measurable. LEO, MEO, and GEO satellites are distinguished.
The spectrum of the object is simultaneously acquired with a resolution of lambda/delta-lambda = 100 in each frame. 
The Solar Gravitational Lens region of Alpha Centauri.  Field of view is 2deg x 2.5 deg, in a 4 minute exposure with 0.28-meter objective prism Schmidt telescope.  The hundreds of vertical streaks are stellar spectra. A laser will show as a PSF-shaped dot.

 

Real-time video of Saturn (below) and Jupiter (above), when a satellite passes.
One field station of SLA, with Sagittarius (left), Scorpio (right). The two brightest objects are Saturn (upper left) and Jupiter (upper right).

 

An artist rendering of communication lasers in the Milky Way Galaxy.

 

Space-Laser-Awareness-Graphic-1024x471

 Proxima Centauri: A search for lasers. 

Top: No flare. Middle: a medium-level flare. Bottom: a super-flare on Proxima Centauri. Laser emission will appear as emission not associated with flares.  Spectra are courtesy of the public ESO data archive.

The spectrum of Vega vs wavelength obtained with the objective prism telescope and QHY600 camera.

 

The spectrum of the planetary nebula, NGC7027, vs. pixels with the objective prism telescope and the QHY600 camera.  H-alpha and [OIII] are separated by 300 pixels