This image shows the sun in the lower left corner, the Earth in the lower right corner, a cloud of small X-shaped spacecraft in the center with
The Great Observatory for Long Wavelengths (GO-LoW), an array of thousands of small satellites.

Great Observatory for Long Wavelengths (GO-LoW) funded by NASA NIAC program

January 25, 2023
Categories: Astronomy , Mary Knapp
The GO-LoW concept has been granted funding by NASA's NIAC.

A visionary Haystack proposal has been selected for funding by the NASA Innovative Advanced Concepts (NIAC) program: the Great Observatory for Long Wavelengths (GO-LoW). Led by Dr. Mary Knapp of MIT Haystack Observatory, the GO-LoW team of scientists and engineers includes Lenny Paritsky (Haystack), Dr. Melodie Kao (University of California, Santa Cruz), and Kat Kononov (MIT). “What excites me most about this project is the opportunity to see the universe in a way that no one ever has before—literally making a brand-new map of the sky,” said Knapp.

GO-LoW aims to reveal the as-of-yet unseen low-frequency radio sky. Scientists have not yet been able to view the universe at these frequencies, as the sky is hidden from ground-based telescopes by the Earth’s ionosphere. Radio signals bounce off the ionosphere, a layer of the atmosphere that contains charged particles, blocking out the low-frequency radio waves from space. Long-wavelength observations require correspondingly large telescopes to see clearly, so traditional dish antenna designs are infeasible in space.

Enter GO-LoW: an array of thousands of tiny, identical satellites—each smaller than a shoebox—working in close coordination together as a group. This observatory will measure low-frequency electromagnetic radiation, which carries crucial information about exoplanetary and stellar magnetic fields (a key missing ingredient for habitability studies) and other astronomical data of high interest.

“GO-LoW is an amazing opportunity for NASA to integrate strengths from mission sizes at both extremes—its lowest-cost, most easily scalable SmallSat missions to the sheer observational power of its generation-defining flagship missions—and open a whole new paradigm for space observatories,” said Kao, a Heising-Simons 51 Pegasi b Fellow. “Humans have never before seen the low-frequency radio sky, and neither have we built a Great Observatory that can change shape to suit the science at hand—or even repair mechanical failures without astronaut intervention. GO-LoW could be the pathway to totally new and unexpected discoveries as well as creating sustainable science infrastructure in space.”

Current space telescopes, such as the James Webb Space Telescope, consist of a single large, expensive spacecraft and are focused on high- and mid-frequency wavelength observations; the GO-LoW project has proposed an observatory composed of thousands of simple, small, and relatively cheap satellites. The array will use interferometry—a technique that combines radio signals from many smaller units into a large virtual telescope—to obtain highly detailed data from exoplanets and other sources in space.

Graphic shows space telescopes and images produced by them across the electromagnetic spectrum above a representation of the Earth's atmospheric opacity across the EM spectrum.  Starting with gamma rays at the left, the graphic shows spacecraft CGRO, then Chandra for X-rays, followed by HST for UV/visible, then Spitzer for infrared.  Finally, GO-Low is represented on the far right side of the diagram as a cloud of small spacecraft.  GO-LoW is designed to access the lowest frequency radio waves at the extreme right side of the atmospheric opacity plot at the bottom of the diagram.
GO-LoW is a Great Observatory concept to open the last unexplored window of the electromagnetic (EM) spectrum. The Earth’s ionosphere becomes opaque at approximately 10m wavelengths, so GO-LoW will join Great Observatories like HST and JWST in space to access this spectral window. (Source image courtesy NASA.)

“I’m excited because this study is so distinct from existing long wavelength concepts: the science target is exoplanetary radio emission, it leverages recent growth in the SmallSat and constellation industry, and it includes a detailed analysis of the sensing antenna,” said Kononov. “I look forward to performing the antenna analysis.” The vector sensor antenna (VSA) shows promise in optimally sensing the electromagnetic field while maintaining a compact form factor. One of the study goals is to analyze the VSA along with other antenna options to determine which will offer the highest per-element sensitivity.

Deploying thousands of satellites will be made possible by several accelerating trends and technology developments in the near future, as will be further investigated in this Phase I study: the falling cost of mass-produced small spacecraft, the advent (and economics) of mega-constellations, and the return of large, high-capacity rockets and lower-cost launches.

Paritsky, who will be leading the GO-LoW architecture study, said, “GO-LoW is the ultimate opportunity to take a truly radical concept—a hundred thousand satellites working together in deep space—and figure out how to make it a reality. I’m excited to dive into the engineering and technology behind the breakthrough science—the launch infrastructure, the satellite architecture, the communications network, the constellation management, and more!”

The last great frontier in radio astronomy—the low-frequency end of the electromagnetic spectrum—is on the verge of a new age, and the NIAC grant for GO-LoW’s initial study on the frontiers of experimental space technology is a notable step forward.