NASA designs new space telescope optics

Research scientists at NASA's Ames Research Center, Moffett Field, Calif., are developing new space telescope optics that won't just detect planets similar to Earth, but actually take photos of them. To take photos, called "direct imaging," a new technology will be used called phase-induced amplitude apodization (PIAA). In development since 2003, it is a proof-of-concept and technology tested prototype that is a strong candidate for NASA's upcoming direct imaging exoplanet missions expected to launch in the 2020 decade and beyond. "By blocking the glare and diffraction from the star, we can start seeing planets that would otherwise be obscured. With this technology, direct imaging confirmation of a habitable zone exoplanet would happen for the first time," said Ruslan Belikov, a NASA astrophycist and technical lead of the coronagraph technical experiment at Ames. Today, scientists use primarily indirect methods, such as the "transit method," to detect extra-solar planets. This method measures the dimming of a star as the planet passes between it and the telescope's line of sight. By observing the changes in starlight, scientists can determine a planet's size, its distance from the host star, and the orbital period. This method is currently used by NASA's Kepler mission, which was launched in 2009 to find Earth-size planets in the habitable zone. In the future, however, a different approach in design and concept may be used to detect common biomarkers of life, such as oxygen and liquid water, on planets similar to Earth orbiting sun-like stars. PIAA is a "direct imaging" technique, which means it takes actual photos of exoplanets. The difficulty in taking such photographs is that the star's brilliance causes diffraction and glare to overwhelm dim planets in orbit around it. To solve this problem, a telescope needs to suppress the diffraction of the starlight.