Our cosmos is awash with radio waves, originating from fierce jets blasting out of distant black holes, blinking dead stars closer to home, and many other exotic objects. To observe radio waves-which possess wavelengths hundreds of thousands of times longer than visible light-astronomers use two types of telescopes: huge single dishes, such as the giant FAST (Five-hundred-meter Aperture Spherical Telescope) in China, and arrays of many dishes, such as the National Radio Astronomy Observatory Very Large Array in New Mexico, whose sprawling 27 dishes were famously featured in the movie Contact.
While the giant single dishes are very sensitive, which means they excel at detecting faint radio waves from across the cosmos, arrays of many dishes can take the sharpest images.
Now, researchers at Caltech are getting ready to build a radio telescope that has both exquisite sensitivity and the ability to take crisp pictures. The Caltech-led Deep Synoptic Array (DSA) recently completed its final design review with Schmidt Sciences , which announced in January that it is funding the project.
The milestone paves the way for construction to begin. Planned for a remote valley in Nevada, the DSA will consist of 1,650 radio dishes, each slightly more than 6 meters in diameter-by far the most dishes to make up a radio array. The array will span an area of about 20 x 16 kilometers. The DSA team plans to build the telescope by 2029, with science operations commencing soon after.
Once completed, the DSA will tout an impressive list of superlatives: It will be the most sensitive radio telescope ever built, produce the highest-quality radio images, and survey the sky 100 times faster than any other radio telescope worldwide.
"The DSA will survey the entire visible sky several times in its first five years at unprecedented speeds," says Gregg Hallinan , principal investigator of DSA, professor of astronomy at Caltech, and director of Caltech's Owens Valley Radio Observatory (OVRO). "While all other radio telescopes combined have so far found about 20 million radio sources, the DSA will match that in the first day of operations. By the end of its initial survey, it will have discovered about 1 billion new radio sources."
The DSA will transform radio astronomy, a discipline Caltech helped pioneer in the US in the 1950s to explore the radio portion of the electromagnetic spectrum. The telescope will discover radio emission from millions of stars, galaxies, and other cosmic characters that shine, pulse, and explode with radio light. It will address the mysteries of black holes, pulsars (magnetized spinning dead stars), and fast radio bursts, or FRBs (brief and powerful flashes of radio waves often originating from very distant sources). It will also probe the physics of dark matter and gravity, and it will measure the structure and expansion of our universe.
"Radio astronomy is about to go from sketch to photograph," says Vikram Ravi , the co-principal investigator of the DSA and a professor of astronomy at Caltech. "The DSA is looking at a far larger volume of the universe far more often than any other telescope. I'm excited for all the discoveries we know we will make, and the ones we don't expect."
