Are we alone in the universe?

For scientists working on NASA’s proposed Habitable Worlds Observatory, that question is no longer purely philosophical. It is increasingly becoming an engineering problem.

Researchers at ΒιΆΉΣ³»­΄«Γ½β€™s are helping develop technology designed to help future space telescopes detect potentially habitable planets orbiting distant stars.

The NASA-funded project, known as PEEPSS (Photonics-Enabled Exoplanet Spectroscopic System), aims to help astronomers directly observe planets hidden within the overwhelming brightness of their parent stars.

β€œIf they’re in the habitable zone, that means they are orbiting close to their host star, and that host star is typically going to be 10 billion times brighter than the planet,” says Professor Stephen Eikenberry, principal investigator on the project.

To explain the difficulty, Eikenberry compares the task to trying to spot β€œa tiny blinking light while someone is shining a spotlight directly in your face.”

The work supports the long-term goals of NASA’s proposed Habitable Worlds Observatory (HWO), a future flagship space telescope intended to search for Earth-like planets beyond our solar system and analyze their atmospheres for signs of life.

Solving One of Astronomy’s Hardest Problems

Astronomers already know planets are common throughout the universe. The challenge now is identifying Earth-like planets that are extraordinarily faint compared to the stars they orbit.

Astronomers use instruments called coronagraphs to block a star’s glare while allowing faint planetary signals to reach a telescope’s detectors.

Even then, however, microscopic imperfections in a telescope’s optics can allow enormous amounts of starlight to leak through the system.

β€œAnd you can say, β€˜Well, that’s only a part in a million,’ ” Eikenberry says. β€œGuess what? A part in a million means it’s still 10,000 times brighter than your exoplanet. You’re doomed.”

The system performs an advanced form of wavefront sensing that detects and corrects tiny distortions in incoming light before they overwhelm planetary signals.

Unlike many existing systems that monitor light earlier in the optical process, PEEPSS performs wavefront sensing directly at the telescope’s focal plane, the same location where scientific imaging occurs.

That distinction is important because it allows researchers to detect and correct optical errors that emerge after light passes through a telescope’s coronagraph. Scientists refer to these distortions as β€œnon-common-path aberrations.”

To explain the concept, Eikenberry compares the system to trying to monitor a room you cannot fully see.

β€œImagine you’re in a house and you want the entire house to be perfectly clean,” he says. β€œYou can see people walking into the bedroom, but you can’t actually see inside the bedroom itself. That’s the non-common path.”

By monitoring the complete optical pathway all the way through to the focal plane, researchers hope PEEPSS can help future observatories achieve the extraordinary precision necessary to detect habitable worlds.

ΒιΆΉΣ³»­΄«Γ½ graduate students Liza Fernanda Quinn Reyes and Genevieve Markees operate photonic lantern fabrication equipment in a CREOL laboratory.
ΒιΆΉΣ³»­΄«Γ½ graduate students Liza Fernanda Quinn Reyes (foreground) and Genevieve Markees work with photonic lantern fabrication equipment in a CREOL laboratory. The technology is being developed as part of the NASA-funded PEEPSS project to improve future exoplanet imaging. (Photo by Antoine Hart)

A New Approach Using Photonic Lanterns

At the center of the project is an emerging technology known as a photonic lantern.

The device separates complex incoming light into individual optical channels, allowing researchers to recover not only brightness information, but also phase information carried by light waves, data that conventional imaging systems typically discard.

Close-up of a precision optical fabrication system used to manufacture photonic lanterns for astrophotonics research.
Precision fabrication equipment used by ΒιΆΉΣ³»­΄«Γ½ researchers to develop photonic lanterns for the NASA-funded PEEPSS project. The technology is designed to improve future observations of Earth-like exoplanets. (Photo by Antoine Hart)

β€œTraditional detectors wipe that information out,” Eikenberry says. β€œPhotonic lanterns allow us to recover it.”

That additional information enables what researchers describe as β€œquantum-inspired imaging,” an emerging technique that uses light behavior to improve image resolution and filter out the remaining starlight.

Researchers at CREOL have become major contributors to the rapidly growing field of astrophotonics, which combines astronomy, fiber optics and advanced photonic technologies.

β€œThere are really only two major centers doing cutting-edge work on photonic lanterns,” Eikenberry says. β€œUs and the University of Sydney in Australia.”

The project brings together collaborators from ΒιΆΉΣ³»­΄«Γ½, University of California, Santa Cruz, the University of Sydney, and the Space Telescope Science Institute. At ΒιΆΉΣ³»­΄«Γ½, Eikenberry works alongside graduate student Genevieve Markees and researchers including Rodrigo Amezcua Correa, Miguel Bandres and Jose-Enrique Antonio-Lopez, whose expertise in fiber optics and photonics helped establish the collaboration.

Looking Toward Habitable Worlds

The current PEEPSS project is structured as a three-year effort focused on building and testing prototype photonic lantern systems in laboratory and telescope environments.

Some versions of the technology have already undergone testing on telescopes in Hawaii through collaborations with the Air Force Research Laboratory and international research partners.

Ultimately, researchers hope the technology could become part of the future NASA missions searching for habitable planets around distant stars.

β€œIf we can identify habitable worlds around other stars and show they possess conditions where Earth-like life could survive, that’s already revolutionary,” Eikenberry says. β€œIf we discover actual evidence of life, then we’re talking about one of the greatest scientific discoveries in human history.”

For Eikenberry, humanity may now be approaching a historic turning point.

β€œWe are one mission away,” he says.

And if future observations succeed, humanity may no longer simply wonder whether life exists elsewhere in the universe. For researchers involved in the project, that possibility is what makes the work so compelling.

β€œWe’ll look up and know.”

The PEEPSS project is supported by NASA through award No. 80NSSC26K0577 and brings together researchers from ΒιΆΉΣ³»­΄«Γ½, the University of Sydney and the University of California, Santa Cruz to develop advanced photonic technologies for future exoplanet imaging and spectroscopy missions, including NASA’s proposed Habitable Worlds Observatory. The initial PEEPSS concept development was supported by the ΒιΆΉΣ³»­΄«Γ½ through its SPICE Academic Excellence Program.