The HabEx team proposed a 4-meter telescope paired with a heliograph and a 52-meter-diameter shadow. (Bertrand Mennesson, a NASA JPL principal scientist and HabEx co-chair, said: “Having both straps and slings is fine.) In addition to providing the potential for 10-ten suppressed, a stellar shadow can image a wide spectrum of light, examining the wavelengths of ozone, oxygen, and water vapor in a single image. (LUVOIR’s exoplanet camera would need to take multiple images to capture the full spectrum of light to find clues to those features.) It could also allow imaging of an alien planet at approx. way smaller than its host star, helping to catch “hidden” planets closer to their sun orbits.
However, the star’s shadow, which must fly separately from the telescope, poses a number of challenges that optical cameras cannot. The need for a separate power source will limit the use of this device to approximately 100 observations or so before it needs to be removed or refueled. It will also require the two defenders to execute a coordinated flight.
And then, of course, there’s the problem that it plays out like origami. Arya and others have been on that mission, creating several large-scale experimental star balls made from sheets of blanket-like Kapton polymers and an unfolding carbon-fiber frame. (“The blanket” is made of several layers of Kapton so that any holes punched in the shade by the meteorite’s micro-impacts won’t affect its shadow.) It wasn’t easy. The edges of the petals of the star’s shadow must be extremely sharp to reflect as little sunlight into the telescope as possible, and any disturbances can affect the exoplanet image. “We are creating a structure with optical precision that has to fold and unfold automatically, and that poses a lot of challenges,” says Arya. “We are approaching these issues step by step and there is still a list of unfinished business to demonstrate the technology.”
Perhaps because the immediate task is so difficult, some astrophysicists believe an exoplanet camera more a star shade can be a perfect one-two punch. “I really see the benefits of a hybrid system,” says Mennesson. Placed from star to star, an exoplanet camera can image a large number of potentially habitable exoplanets, then the star’s shadow can provide High-resolution view with wide bandwidth and light flux of each planet — great for an in-depth description of its habitability. The HabEx and LUVOIR teams have worked closely together, and any future teams will likely attract their members.
Star nuances could also be useful for many deep space missions. NASA funded Mather’s team to work on using orbiting stellar balloons to detect extraterrestrial planets. KILLER WHALES, or Orbitable Configurable Artificial Star, will be the first hybrid ground-based space observatory, using space-based laser beacons to help focus telescopes on the ground, thus eliminating Eliminate the distortion caused by seeing through the atmosphere. The next step in the proposal would see the 100-meter-long “RemoteOcculter” stellar shadow in near-Earth orbit, where it would cast a shadow on the telescope. “It’s much more difficult to orbit the ball,” Mather wrote in an email, but it could be the ultimate alien planet observation system. “Using it, we can see the Earth orbiting a nearby star in a one-minute exposure time, and in an hour we can tell if it has water and oxygen like ours. ”
Decisions about which of these projects will continue to take place over the years. Direction for HabEx and LUVOIR could be laid out during NASA’s Town Hall meeting at the American Astronomical Society meeting on January 11, and the ORCAS and RemoteOcculter mission proposals are still being worked on. But the James Webb Space Telescope, which launched in December, will soon capture replays taken with the help of its lower-contrast stellar shadow. That telescope will be fully operational by mid-2022, and it is expected to become the new leader in the hunt for alien planets — until even more powerful pitchers emerge.
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