Casting a Shadow in the Darkness of Space

The Jet Propulsion Lab’s Starshade occulter could give space-based telescopes a sharper view of exoplanets, increasing our chances of finding another Earth.

NASA, telescope, starshade, exoplanet, Earth, JPL, For the past 15 years astronomers across the globe have been examining distant stars, looking for faint changes in light intensity that might alert them to the presence of a foreign world. While this indirect detection method has resulted in the discovery of about 1800 exoplanets, no planet beyond our own solar system has been directly imaged. In the coming years, that may change.

Named the Starshade, NASA JPL’s idea for taking a crisp snapshot of a planet outside of our solar system is a sunflower-shaped shade with a viewing port at its center. Astronomers and engineers believe the Starshade could be attached to the face of a space telescope, which would then be flown to the imager’s observation location. Once in place, the Starshade will decouple from the telescope and fly some 129,000km (80,000 miles) away. When sufficiently far from the telescope’s optics, the Starshade will unfurl its enormous blind, reducing the interference of wayward starlight 10-billion fold. According to some estimates, a reasonably sized Starshade could allow astronomers to directly image the atmospheres of worlds tens of trillions of miles away.

While the Starshade’s primary function is to block photonic noise, JPL researchers maintain that the optic-umbrella will also aid imaging by controlling the path of light reaching the telescope’s sensors. “The shape of the petals, when seen from far away, creates a softer edge that causes less bending of light waves,” said Dr. Stuart Shaklan, JPL’s lead engineer on the Starshade project. “Less light bending means that the Starshade shadow is very dark, so the telescope can take images of the planets without being overwhelmed by starlight.”

If JPL’s Starshade ever makes it into space, astronomers are confident it could be the technological key that opens a clear view to Earth-like worlds in galaxies far away. “A starshade mission would allow us to directly image Earth-size, rocky exoplanets” said Jeremy Kasdin, Principal Investigator of the Starshade project. “We’ll be able to show people a picture of a dot and explain that that’s another Earth.”

Image and Video Courtesy of NASA JPL