A report proposes the development of a white-light nulling interferometer to be used in conjunction with a single-aperture astronomical telescope that would be operated in outer space. When such a telescope is aimed at a given star, the interferometer would suppress the light of that star while passing enough light from planets (if any) orbiting the star, to enable imaging or spectroscopic examination of the planets. In a nulling interferometer, according to the proposal, scattered light would be suppressed by spatial filtering in an array of single-mode optical fibers rather than by requiring optical surfaces to be accurate within 1/4,000 wavelength as in a coronagraph or an apodized telescope. As a result, angstrom-level precision would be needed in only the small nulling combiner, and not in large, meter-sized optics. The nulling interferometer could work as an independent instrument in space or in conjunction with a coronagraphic system to detect planets outside our solar system.
This work was done by Bertrand Mennesson, Eugene Serabyn, Michael Shao, and Bruce Levine of Caltech for NASA's Jet Propulsion Laboratory. NPO-30547
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White-Light Nulling Interferometers for Detecting Planets
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Overview
The document titled "White-Light Nulling Interferometers for Detecting Planets" from NASA's Jet Propulsion Laboratory outlines a significant advancement in astronomical technology aimed at detecting exoplanets, particularly Earth-like planets. The primary innovation discussed is the integration of a white-light nulling interferometer with a conventional astronomical telescope in space. This combination allows for the effective suppression of starlight, which is crucial for imaging and spectroscopic analysis of planets that orbit stars.
One of the major challenges in detecting exoplanets is the overwhelming brightness of starlight compared to the light reflected from the planets, with ratios ranging from 10^7 to 10^9, depending on the wavelength. This makes it extremely difficult to capture clear images or spectra of the planets' atmospheres. The document presents a solution through the use of a visible-light nulling instrument positioned in the pupil plane of a filled aperture telescope. This instrument works by interfering light from different parts of the telescope's pupil, allowing it to effectively cancel out the starlight while enabling the detection of the planet's light.
The proposed system not only aims to provide direct images of planets but also facilitates spectroscopic measurements that can identify the presence of Earth-like atmospheric gases. This capability is essential for assessing the habitability of these distant worlds and could significantly advance our understanding of planetary systems beyond our own.
The document emphasizes the technical and financial feasibility of this approach, which eliminates the need for super-smooth optical surfaces on telescopes, making the Terrestrial Planet Finder Mission more achievable. It highlights the potential for broader applications of this technology in various fields, including aerospace and commercial sectors.
For further inquiries or detailed information, the document provides contact details for the Intellectual Assets Office at NASA, as well as resources for additional research and technology related to this area. Overall, this technical support package represents a promising step forward in the quest to discover and analyze planets outside our solar system, contributing to the ongoing exploration of the universe.
