\n
The Mid-Infrared Instrument (MIRI) is one of the three scientific instruments to fly on the James Webb Space Telescope (JWST), which is due for launch in 2013. MIRI contains two sub-instruments, an imager, which has low resolution spectroscopy and coronagraphic capabilities in addition to imaging, and a medium resolution IFU spectrometer. A verification model of MIRI was assembled in 2007 and a cold test campaign was conducted between November 2007 and February 2008. This model was the first scientifically representative model, allowing a first assessment to be made of the performance. This paper describes the test facility and testing done. It also reports on the first results from this test campaign.
\n
\n
MIRI is the mid-IR instrument for the James Webb Space Telescope and provides imaging, coronography and integral field spectroscopy over the 5-28μm wavelength range. MIRI is the only instrument which is cooled to 7K by a dedicated cooler, much lower than the passively cooled 40K of the rest of JWST, which introduces unique challenges. The paper will describe the key features of the overall instrument design. The flight model design of the MIRI Optical System is completed, with hardware now in manufacture across Europe and the USA, while the MIRI Cooler System is at PDR level development. A brief description of how the different development stages of the optical and cooling systems are accommodated is provided, but the paper largely describes progress with the MIRI Optical System. We report the current status of the development and provide an overview of the results from the qualification and test programme.
\n
\n
The Pupil mapping Exoplanet Coronagraphic Observer (PECO) mission concept is a 1.4-m telescope aimed at imaging and characterizing extra-solar planetary systems at optical wavelengths. The coronagraphic method employed, Phase-Induced Amplitude Apodization or PIAA (a.k.a. pupil mapping) can deliver 1e-10 contrast at 2 lambda/D and uses almost all the starlight that passes through the aperture to maintain higher throughput and higher angular resolution than any other coronagraph or nuller, making PECO the theoretically most efficient existing approach for imaging extra-solar planetary systems. PECO's instrument also incorporates deformable mirrors for high accuracy wavefront control. Our studies show that a probe-scale PECO mission with 1.4 m aperture is extremely powerful, with the capability of imaging at spectral resolution R≈∠15 the habitable zones of already known F, G, K stars with sensitivity sufficient to detect planets down to Earth size, and to map dust clouds down to a fraction of our zodiacal cloud dust brightness. PECO will acquire narrow field images simultaneously in 10 to 20 spectral bands covering wavelengths from 0.4 to 1.0 μm and will utilize all available photons for maximum wavefront sensing and imaging/spectroscopy sensitivity. This approach is well suited for low-resolution spectral characterization of both planets and dust clouds with a moderately sized telescope. We also report on recent results obtained with the laboratory prototype of a coronagraphic low order wavefront sensor (CLOWFS) for PIAA coronagraph. The CLOWFS is a key part of PECO's design and will enable high contrast at the very small PECO inner working angle.
\n
\n
This paper addresses the performance of a suite of grisms as part of an Astrobiology Science and Instrument Development (ASTID) Program to implement a moderate resolution spectroscopic capability in the mid/far-IR facility instrument FORCAST for the Stratospheric Observatory For Infrared Astronomy (SOFIA). A moderate resolution mid-IR spectrometer on SOFIA will offer advantages not available to either ground or space-based instruments after the Spitzer Space Telescope ceases operation in ~2008. SOFIA will begin operations in 2008 and will have an operational lifetime of ~20 years. From aircraft altitudes, it will be possible to cover a wide range of wavelengths, particularly in the critical 5-9 micron band, where detection of astrobiologically interesting molecules have key spectral signatures that are not accessible from the ground The FORCAST grism suite consists of six grisms: four monolithic Si grisms and two KRS-5 grisms. These devices will allow long-slit low-resolution (R = 100-300) and short-slit, cross-dispersed high-resolution spectroscopic modes (R = 800-1200) over select wavelengths in the 5-40 μm spectral range and enable observing programs to gather both images and spectra in a single SOFIA flight. The silicon grisms demonstrate a new family of dispersive elements with good optical performance for spectroscopy from 1.2-8 μm and beyond 18 μm. After SOFIA flies, the grism modes in FORCAST will complement other first generation instruments on SOFIA and provide follow-up capability of bright sources observed with Infrared Spectrograph (IRS) on Spitzer. This paper highlights the design of the grism suite for FORCAST and the current laboratory cryogenic performance of the silicon grisms.
\n
\n
The Telescope to Observe Planetary Systems (TOPS) is a proposed space mission to image in the visible (0.4- 0.9 μm) planetary systems of nearby stars simultaneously in 16 spectral bands (resolution R≈20). For the ≈10 most favorable stars, it will have the sensitivity to discover 2RΕ rocky planets within habitable zones and characterize their surfaces or atmospheres through spectrophotometry. Many more massive planets and debris discs will be imaged and characterized for the first time. With a 1.2m visible telescope, the proposed mission achieves its power by exploiting the most efficient and robust coronagraphic and wavefront control techniques. The Phase-Induced Amplitude Apodization (PIAA) coronagraph used by TOPS allows planet detection at 2λ/d with nearly 100% throughput and preserves the telescope angular resolution. An efficient focal plane wavefront sensing scheme accurately measures wavefront aberrations which are fed back to the telescope active primary mirror. Fine wavefront control is also performed independently in each of 4 spectral channels, resulting in a system that is robust to wavefront chromaticity.
\n
\n
The MIRI is the mid-IR instrument for JWST and provides imaging, coronography and low and medium resolution spectroscopy over the 5-28μm band. In this paper we provide an overview of the key driving requirements and design status.
\n