What’s most difficult in finding Earth-like exoplanets that may support life is pretty much what you’d guess – the brightness of distant stars overwhelms the ability to see planets of this size. Existing and planned space and ground-based telescopes use indirect methods to detect planets around other stars, and there are many limitations to these indirect methods, especially when it comes to smaller planets.
So, scientists at NASA’s Goddard Space Flight Center designed a ground-breaking instrument in order to be able to directly detect exoplanets. A fascinating article on the NASA website explains:
A potentially revolutionary instrument now being developed to first find Earth-like planets in other solar systems and then study their atmospheres to identify chemical signatures of life has just passed another technological hurdle that makes it an even stronger contender for a future astrophysics mission.
The instrument, called the Visible Nulling Coronagraph (VNC), combines an interferometer with a coronagraph — in itself a first. It’s well on its way to demonstrating operations over a broader spectral range, including the ultraviolet, visible, and near-infrared bands, said Brian Hicks, a fellow with NASA’s Postdoctoral Program who is working with VNC Principal Investigators Rick Lyon and Mark Clampin, who are scientists at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
“The VNC is demonstrating the spectral range needed for planet characterization,” Hicks said. “It will be more sensitive for finding fainter planets. It also will enable spectroscopy, which is what NASA will need to study the atmospheres of exoplanets to identify signatures of water, oxygen, carbon dioxide, methane, and ozone — the chemistry we associate with habitability for life as we know it.”
Currently, the Kepler Observatory uses indirect means to detect exoplanets, as will the James Webb Space Telescope and the Transiting Exoplanet Survey Satellite in the future.
The next logical step is direct detection using a next-generation space observatory equipped with highly sophisticated instruments, including a coronagraph or occulting star shade that would block starlight and allow the observatory to directly image faint Earth-like exoplanets.
The VNC, which Clampin and Lyon started developing nearly six years ago, is ideally suited to this task. Its pupil-based technique for separating star from planet light is naturally compatible with segmented or arbitrarily shaped telescope mirrors, similar to the one that will form the heart of the Webb Observatory. Such a mirror folds up for launch and then unfolds once the observatory reaches its orbital destination.
The article details how the VNC uses very innovative technology to split the light gathered by the telescope it is integrated with into two channels, called the light and the dark channels. Starlight goes to the light channel, and planet light goes to the dark channel. Then the dark channel is then analyzed by a spectrograph and an imager to determine the physical properties of any planet that is found.
Check out the excellent and detailed article on the NASA website which goes into much deeper technical detail on how this revolutionary new exoplanet detecting technology will get the job done.
Source: NASA.gov – “Innovative Planet-Finding Technology Passes Another Hurdle“
Featured Image Credit: NASA/W. Hrybyk