The Fourier-Kelvin Stellar Interferometer (FKSI) is a mission concept for a nulling interferometer for the near-to-mid-infrared spectral region (3-8µm). FKSI is conceived as a scientific and technological precursor to TPF. The scientific emphasis of the mission is on the evolution of protostellar systems, from just after the collapse of the precursor molecular cloud core, through the formation of the disk surrounding the protostar, the formation of planets in the disk, and eventual dispersal of the disk material. FKSI will answer key questions about extrasolar planets:
Σ What are the characteristics of the known extrasolar giant planets?
Σ What are the characteristics of the extrasolar zodiacal clouds around nearby stars?
Σ Are there giant planets around classes of stars other than those already studied?
We present preliminary results of a detailed design study of the FKSI. Using a nulling interferometer configuration, the optical system consists of two 0.5m telescopes on a 12.5m boom feeding a Mach-Zender beam combiner with a fiber wavefront error reducer to produce a 0.01% null of the central starlight. With this system, planets around nearby stars can be detected and characterized using a combination of spectral and spatial resolution.
The Extrasolar Planetary Imaging Coronagraph (EPIC) will provide the first direct measurements of a broad range of fundamental physical characteristics of giant planets in other solar systems. These characteristics include orbital inclination, mass, brightness, color, the presence (or absence) of CH4 and H2O, and orbital or rotational-driven variability. EPIC utilizes a 1.5 meter telescope coupled to a Visible Nulling Coronagraph to achieve these science goals. EPIC has been proposed as a Discovery Mission.
A concept is presented for a 10-meter sparse aperture hypertelescoep to detect extrasolar planets by direct imaging from the ground through the turbulent atmosphere. The telescope achieves high dynamic range with good image quality very close to bright stellar sources using pupil densification techniques and real-time atmospheric correction. Active correction of the perturbed wavefront is greatly simplified by several unique design features of the telescope: 1) use of an array of 19 small subaperture flat mirrors, 2) mounting the flats on a steerable parabolic truss structure, 3) operating in the near-IR, and 4) making the subaperture flats comparable in size to the seeing cells. These features relax the requirements on the wavefront sensing and control system. This paper describes the general concept. The details of design and implementation will be addresed separately.
KEYWORDS: Planets, Stars, Imaging systems, Jupiter, Telescopes, Diffraction, Signal to noise ratio, Point spread functions, Space telescopes, Doppler effect
The Extra-Solar Planetary Imager (ESPI) is envisioned as a space based, high dynamic range, visible imager capable of detecting Jovian like planets. Initially proposed as a NASA Midex (NASA/Medium Class Explorer) mission (PI:Gary Melnick), as a space-based 1.5 x 1.5 m2 Jacquinot apodized square aperture telescope. The combination of apodization and a square aperture telescope reduces the diffracted light from a bright central source increasing the planetary to stellar contrast over much of the telescope focal plane. As a result, observations of very faint astronomical objects next to bright sources with angular separations as small as 0.32 arcseconds become possible. This permits a sensitive search for exo-planets in reflected light. ESPI is capable of detecting a Jupiter-like planet in a relatively long-period orbit around as many as 160 to 175 stars with a signal-to-noise ratio > 5 in observations lasting maximally 100 hours per star out to ~16 parsecs. We discuss the scientific ramifications, an overview of the system design including apodizing a square aperture, signal to noise issues and the effect of wavefront errors and the scalability of ESPI with respect to NASA's Terrestrial Planet Finder mission.
The Extrasolar Planet Observatory (ExPO) is envisioned as a Discovery-class space telescope for the direct detection and characterization of extra-solar planets. ExPO would also demonstrate the feasibility of a number of technologies which could be critical to the ultimate success of the Terrestrial Planet Finder mission. ExPO would detect a wide range of planet types in the visible and near IR, and do spectrophotometry and spectroscopy on many of the detected objects. The apoodized square aperture coronagraphic space telescope is designed to resolve faint companions near much brighter point-like sources by achieving very high dynamic range imaging at separations as small as 0.1 arcsec.
Far infrared interferometers in space would enable extraordinary measurements of the early universe, the formation of galaxies, stars, and planets, and would have great discovery potential. Since half the luminosity of the universe and 98% of the photons released since the Big Bang are now observable at far IR wavelengths (40 - 500 micrometers ), and the Earth's atmosphere prevents sensitive observations from the ground, this is one of the last unexplored frontiers of space astronomy. We present the engineering and technology requirements that stem from a set of compelling scientific goals and discuss possible configurations for two proposed NASA missions, the Space Infrared Interferometric Telescope and the Submillimeter Probe of the Evolution of Cosmic Structure.
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