From Earth, distant stars look like mere pinpricks of light peeking through a black canvas.
But from outer space, their glare is overwhelming, blotting out any chance of seeing planets orbiting other stars.
With that in mind, NASA fit its new space telescope with a set of sophisticated sunglasses—er, “starglasses.”
The multi-layered coronagraph instrument features a system of masks, prisms, detectors, and self-flexing mirrors built to block out the dazzling light of distant stars, revealing exoplanets around them.
“What we’re trying to do is cancel out a billion photons [particles of light] from the star for every one we capture from the planet,” according to Jason Rhodes, project scientist for the Wide-Field Infrared Survey Telescope (WFIRST) at NASA’s Jet Propulsion Laboratory.
As light that’s traveled tens of light-years from an exoplanet enters the telescope, thousands of actuators move like pistons, changing the shape of two flexible mirrors in real time.
These mirrors, in tandem with high-tech “masks,” squelch the star’s diffraction—the bending of light waves around the edges of light-blocking elements inside the coronagraph.
As a result, blinding starlight is sharply dimmed, allowing faintly glowing, previously hidden planets to appear.
“With WFIRST we’ll be able to get images and spectra of these large planets, with the goal of proving technologies that will be used in a future mission—to eventually look at small rocky planets that could have liquid water on their surfaces, or even signs of life, like our own,” Rhodes said.
WFIRST’s coronagraph could deliver the clearest-ever images of distant star systems’ formative years, and yield deep insights into how our Solar System formed.
“This may be the most complicated astronomical instrument ever flown,” Rhodes added.
Once successfully demonstrated over the mission’s first 18 months, the so-called “starglasses” could become open to the scientific community.
The device just completed a preliminary design review, meaning it met all design, schedule, and budget requirements, and the team can move forward with building hardware to fly in space.
By the time it launches in the mid-2020s, WFIRST will be the third such mission to include coronagraph technology—following the Hubble Space Telescope (in orbit since 1990) and the James Webb Space Telescope (lifting off in 2021).
It is the first, though, to feature the starlight suppression capability.
“WFIRST should be two or three orders of magnitude more powerful than any other coronagraph ever flown,” Rhodes said. “There should be a chance for some really compelling science, even though it’s just a tech demo.”
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