Researchers from MIT Lincoln Laboratory, the MIT Haystack Observatory, and Lowell Observatory are working on a NASA-funded concept study called the Great Observatory for Long Wavelengths, or GO-LoW, that outlines a method to view the universe at as-of-yet unseen low frequencies using a constellation of thousands of small satellites. The wavelengths of these frequencies are 15 meters to several kilometers in length, which means they require a very big telescope in order to see clearly.
"GO-LoW will be a new kind of telescope, made up of many thousands of spacecraft that work together semi-autonomously, with limited input from Earth," says Mary Knapp, the principal investigator for GO-LoW at the MIT Haystack Observatory. "GO-LoW will allow humans to see the universe in a new light, opening up one of the very last frontiers in the electromagnetic spectrum."
The difficulty in viewing the low-frequency radio sky comes from Earth's ionosphere, a layer of the atmosphere that contains charged particles that prevent very low-frequency radio waves from passing through. Therefore, a space-based instrument is required to observe these wavelengths. Another challenge is that long-wavelength observations require correspondingly large telescopes, which would need to be many kilometers in length if built using traditional dish antenna designs. GO-LoW will use interferometry - a technique that combines signals from many spatially separated receivers that, when put together, will function as one large telescope - to obtain highly detailed data from exoplanets and other sources in space. A similar technique was used to make the first image of a black hole and, more recently, an image of the first known extrasolar radiation belts.
Melodie Kao, a member of the team from Lowell Observatory, says the data could reveal details about an exoplanet's makeup and potential for life. "[The radio wave aurora around an exoplanet] carries important information, such as whether or not the planet has a magnetic field, how strong it is, how fast the planet is rotating, and even hints about what's inside," she says. "Studying exoplanet radio aurorae and the magnetic fields that they trace is an important piece of the habitability puzzle, and it's a key science goal for GO-LoW."
Several recent trends and technology developments will make GO-LoW possible in the near future, such as the declining cost of mass-produced small satellites, the rise of mega-constellations, and the return of large, high-capacity launch vehicles like NASA's Space Launch System. Go-LoW would be the first mega-constellation that uses interferometry for scientific purposes.
The GO-LoW constellation will be built through several successive launches, each containing thousands of spacecraft. Once they reach low-Earth orbit, the spacecraft will be refueled before journeying on to their final destination - an Earth-sun Lagrange point where they will then be deployed. Lagrange points are regions in space where the gravitational forces of two large celestial bodies (like the sun and Earth) are in equilibrium, such that a spacecraft requires minimal fuel to maintain its position relative to the two larger bodies. At this long distance from Earth (1 astronomical unit, or approximately 93 million miles), there will also be much less radio-frequency interference that would otherwise obscure GO-LoW's sensitive measurements.
"GO-LoW will have a hierarchical architecture consisting of thousands of small listener nodes and a smaller number of larger communication and computation nodes (CCNs)," says Kat Kononov, a team member from Lincoln Laboratory's Applied Space Systems Group, who has been working with MIT Haystack staff since 2020, with Knapp serving as her mentor during graduate school. A node refers to an individual small satellite within the constellation. "The listener nodes are small, relatively simple 3U CubeSats - about the size of a loaf of bread - that collect data with their low-frequency antennas, store it in memory, and periodically send it to their communication and computation node via a radio link." In comparison, the CCNs are about the size of a mini-fridge.
The CCN will keep track of the positions of the listener nodes in their neighborhood; collect and reduce the data from their respective listener nodes (around 100 of them); and then transmit that data back to Earth, where more intensive data processing can be performed.
At full strength, with approximately 100,000 listener nodes, the GO-LoW constellation should be able to see exoplanets with magnetic fields in the solar neighborhood - within 5 to 10 parsecs - many for the very first time.
The GO-LoW research team recently published the results of their findings from Phase I of the study, which identified a type of advanced antenna called a vector sensor as the best type for this application. In 2024, Lincoln Laboratory designed a compact deployable version of the sensor suitable for use in space.
The team is now working on Phase II of the program, which is to build a multi-agent simulation of constellation operations.
"What we learned during the Phase I study is that the hard part for GO-LoW is not any specific technology ... the hard part is the system: the system engineering and the autonomy to run the system," says Knapp. "So, how do we build this constellation such that it's a tractable problem? That's what we're exploring in this next part of the study."
GO-LoW is one of many civil space programs at Lincoln Laboratory that aim to harness advanced technologies originally developed for national security to enable new space missions that support science and society. "By adapting these capabilities to serve new stakeholders, the laboratory helps open novel frontiers of discovery while building resilient, cost-effective systems that benefit the nation and the world," says Laura Kennedy, who is the deputy lead of Lincoln Laboratory's Civil Space Systems and Technology Office.
"Like landing on the moon in 1969, or launching Hubble in the 1990s, GO-LoW is envisioned to let us see something we've never seen before and generate scientific breakthroughs," says Kononov.
Go-LoW is a collaboration between Lincoln Laboratory, Haystack Observatory, and Lowell University, as well as Lenny Paritsky from LeafLabs and Jacob Turner from Cornell University.
Research Report:Great Observatory for Long Wavelengths (GO-LoW) NIAC Phase I Final Report"
Research Report:"Development of the Deployable HF Vector Sensor for the AERO-VISTA Spacecraft"
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