This paper discusses the optical design of the Origins Space Telescope. Origins is one of four large missions under study in preparation for the 2020 Decadal Survey in Astronomy and Astrophysics. Sensitive to the mid- and far-infrared spectrum (between 2.8 and 588 μm), Origins sets out to answer a number of important scientific questions by addressing NASA’s three key science goals in astrophysics. The Origins telescope has a 5.9 m diameter primary mirror and operates at f/14. The large on-axis primary consists of 18 ‘keystone’ segments of two different prescriptions arranged in two annuli (six inner and twelve outer segments) that together form a circular aperture in the goal of achieving a symmetric point spread function. To accommodate the 46 x 15 arcminute full field of view of the telescope at the design wavelength of λ = 30 μm, a three-mirror anastigmat configuration is used. The design is diffraction-limited across its instruments’ fields of view. A brief discussion of each of the three baselined instruments within the Instrument Accommodation Module (IAM) is presented: 1) Origins Survey Spectrometer (OSS), 2) Mid-infrared Spectrometer, Camera (MISC) transit spectrometer channel, and 3) Far-Infrared Polarimeter/Imager (FIP). In addition, the upscope options for the observatory are laid out as well including a fourth instrument: the Heterodyne Receiver for Origins (HERO).
The Origins Space Telescope will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did galaxies evolve from the earliest galactic systems to those found in the universe today? How do habitable planets form? How common are life-bearing worlds? To answer these alluring questions, Origins will operate at mid- and far-infrared wavelengths and offer powerful spectroscopic instruments and sensitivity three orders of magnitude better than that of Herschel, the largest telescope flown in space to date. After a 3 ½ year study, the Origins Science and Technology Definition Team will recommend to the Decadal Survey a concept for Origins with a 5.9-m diameter telescope cryocooled to 4.5 K and equipped with three scientific instruments. A mid-infrared instrument (MISC-T) will measure the spectra of transiting exoplanets in the 2.8 – 20 μm wavelength range and offer unprecedented sensitivity, enabling definitive biosignature detections. The Far-IR Imager Polarimeter (FIP) will be able to survey thousands of square degrees with broadband imaging at 50 and 250 μm. The Origins Survey Spectrometer (OSS) will cover wavelengths from 25 – 588 μm, make wide-area and deep spectroscopic surveys with spectral resolving power R ~ 300, and pointed observations at R ~ 40,000 and 300,000 with selectable instrument modes. Origins was designed to minimize complexity. The telescope has a Spitzer-like architecture and requires very few deployments after launch. The cryo-thermal system design leverages JWST technology and experience. A combination of current-state-of-the-art cryocoolers and next-generation detector technology will enable Origins’ natural backgroundlimited sensitivity.
The OSS on the Origins Space Telescope is designed to decode the cosmic history of nucleosynthesis, star formation, and supermassive black hole growth with wide-area spatial-spectral 3-D surveys across the full 25 to 590 micron band. Six wideband grating modules combine to cover the full band at R=300, each couples a long slit with 60-190 beams on the sky. OSS will have a total of 120,000 background-limited detector pixels in the six 2-D arrays which provide spatial and spectral coverage. The suite of grating modules can be used for pointed observations of targets of interest, and are particularly powerful for 3-D spectral spectral surveys. To chart the transition from interstellar material, particularly water, to planetary systems, two high-spectral-resolution modes are included. The first incorporates a Fourier-transform spectrometer (FTS) in front of the gratings providing resolving power of 25,000 (δv = 12 km/s) at 179 µm to resolve water emission in protoplanetary disk spectra. The second boosts the FTS capability with an additional etalon (Fabry-Perot interferometer) to provide 2 km/s resolution in this line to enable detailed structural studies of disks in the various water and HD lines. Optical, thermal, and mechanical designs are presented, and the system approach to the detector readout enabling the large formats is described.
The Origins Space Telescope (OST) is the mission concept for the Far-Infrared Surveyor, one of the four science and technology definition studies of NASA Headquarters for the 2020 Astronomy and Astrophysics Decadal survey. "Concept-1" is a cold (4 K) 9 m space telescope with five instruments, while "concept 2" consists of a cold 5.9 m telescope and four instruments, providing imaging and spectroscopic capabilities between 5μm and 600μm. The sensitivity provided by the observatory will be a three to four orders of magnitude improvement over currently achieved observational capabilities, allowing to address a wide range of new and so far inaccessible scientific questions, ranging from bio-signatures in the atmospheres of exo-planets to the production of the first metals in the universe right after the end of re-ionization. Here we present the Far Infrared Imager and Polarimeter (FIP) for OST. The camera will cover four bands, 50μm, 100μm, 250μm, and 500μm. In the "concept 1" version of the instrument, FIP will allow for differential polarimetry with the ability to observe two colors simultaneously, while all four bands can be observed simultaneously in total power mode. The confusion limit in the total power mode will be reached in only 8 ms at 500μm, while at 50μm the source density in the sky is so low that at OST's angular resolution of (see manuscript for symbol) 2" in this band the source confusion limit will only be reached after about two hours of integration with the "concept-2" version of FIP ("concept-1" FIP will not be confusion limited at 50m, no matter how long it integrates). Science topics that can be addressed by the camera include, but are not limited to, galactic and extragalactic magnetic field studies, deep galaxy surveys, and outer Solar System objects.
The Origins Space Telescope (OST) is a NASA study for a large satellite mission to be submitted to the 2020 Decadal Review. The proposed satellite has a fleet of instruments including the HEterodyne Receivers for OST (HERO). HERO is designed around the quest to follow the trail of water from the ISM to disks around protostars and planets. HERO will perform high-spectral resolution measurements with 2x9 pixel focal plane arrays at any frequency between 468GHz to 2,700GHz (617 to 111 μm). HERO builds on the successful Herschel/HIFI heritage, as well as recent technological innovations, allowing it to surpass any prior heterodyne instrument in terms of sensitivity and spectral coverage.
The Origins Space Telescope (OST) mission concept study is the subject of one of the four science and technology definition studies supported by NASA Headquarters to prepare for the 2020 Astronomy and Astrophysics Decadal Survey. OST will survey the most distant galaxies to discern the rise of metals and dust and to unveil the co-evolution of galaxy and blackhole formation, study the Milky Way to follow the path of water from the interstellar medium to habitable worlds in planetary systems, and measure biosignatures from exoplanets. This paper describes the science drivers and how they drove key requirements for OST Mission Concept 2, which will operate between ~5 and ~600 microns with a JWST sized telescope. Mission Concept 2 for the OST study optimizes the engineering for the key science cases into a powerful and more economical observatory compared to Mission Concept 1.
The Origins Space Telescope (OST) will trace the history of our origins from the time dust and heavy elements permanently altered the cosmic landscape to present-day life. How did the universe evolve in response to its changing ingredients? How common are life-bearing planets? To accomplish its scientific objectives, OST will operate at mid- and far-infrared wavelengths and offer superlative sensitivity and new spectroscopic capabilities. The OST study team will present a scientifically compelling, executable mission concept to the 2020 Decadal Survey in Astrophysics. To understand the concept solution space, our team studied two alternative mission concepts. We report on the study approach and describe both of these concepts, give the rationale for major design decisions, and briefly describe the mission-enabling technology.
We present the key scientific questions that can be addressed by GMOX, a Multi-Object Spectrograph selected for feasibility study as a 4th generation instrument for the Gemini telescopes. Using commercial digital micro-mirror devices (DMDs) as slit selection mechanisms, GMOX can observe hundreds of sources at R~5000 between the U and K band simultaneously. Exploiting the narrow PSF delivered by the Gemini South GeMS MCAO module, GMOX can synthesize slits as small as 40mas reaching extremely faint magnitude limits, and thus enabling a plethora of applications and innovative science. Our main scientific driver in developing GMOX has been Resolving galaxies through cosmic time: GMOX 40mas slit (at GeMS) corresponds to 300 pc at z ~ 1:5, where the angular diameter distance reaches its maximum, and therefore to even smaller linear scales at any other redshift. This means that GMOX can take spectra of regions smaller than 300 pc in the whole observable Universe, allowing to probe the growth and evolution of galaxies with unprecedented detail. GMOXs multi-object capability and high angular resolution enable efficient studies of crowded fields, such as globular clusters, the Milky Way bulge, the Magellanic Clouds, Local Group galaxies and galaxy clusters. The wide-band simultaneous coverage and the very fast slit configuration mechanisms also make GMOX ideal for follow-up of LSST transients.
This paper describes the beginning of the Far-Infrared Surveyor mission study for NASA’s Astrophysics Decadal 2020.
We describe the scope of the study, and the open process approach of the Science and Technology Definition Team. We
are currently developing the science cases and provide some preliminary highlights here. We note key areas for
technological innovation and improvements necessary to make a Far-Infrared Surveyor mission a reality.
MIRI is one of four instruments to be built for the James Webb Space Telescope. It provides imaging, coronography and
integral field spectroscopy over the 5-28.5um 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, and consists of both an Optical System
and a Cooler System. This paper will describe the key features of the overall instrument design and then concentrate on
the status of the MIRI Optical System development. The flight model design and manufacture is complete, and final
assembly and test of the integrated instrument is now underway. Prior to integration, all of the major subassemblies have
undergone individual environmental qualification and performance tests and end-end testing of a flight representative
model has been carried out. The paper will provide an overview of results from this testing and describe the current
status of the flight model build and the plan for performance verification and ground calibration.
The WIYN High Resolution Infrared Camera (WHIRC) has been a general-use instrument at the WIYN telescope on
Kitt Peak since 2008. WHIRC is a near-infrared (0.8 - 2.5 μm) camera with a filter complement of J, H, Ks broadband
and 10 narrowband filters, utilizing a 2048 × 2048 HgCdTe array from Raytheon's VIRGO line, developed for the
VISTA project. The compact on-axis refractive optical design makes WHIRC the smallest near-IR camera with this
capability. WHIRC is installed on the WIYN Tip-Tilt Module (WTTM) port and can achieve near diffraction-limited
imaging with a FWHM of ~0.25 arcsec at Ks with active WTTM correction and routinely delivers ~0.6 arcsec FWHM
images without WTTM correction. During its first year of general use operation at WIYN, WHIRC has been used for
high definition near-infrared imaging studies of a wide range of astronomical phenomena including star formation
regions, stellar populations and interstellar medium in nearby galaxies, high-z galaxies and transient phenomena. We
discuss performance and data reduction issues such as distortion, pupil ghost, and fringe removal and the development of
new tools for the observing community such as an exposure time calculator and data reduction pipeline.
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.
We present the design overview and on-telescope performance of the WIYN High Resolution Infrared Camera
(WHIRC). As a dedicated near-infrared (0.8-2.5 μm) camera on the WIYN Tip-Tilt Module (WTTM), WHIRC will
provide near diffraction-limited imaging with a typical FWHM of ~0.25". WHIRC uses a 2048 x 2048 HgCdTe array
from Raytheon's VIRGO line, which is a spinoff from the VISTA project. The WHIRC filter complement includes J, H
KS, and 10 narrowband filters. WHIRC's compact design makes it the smallest near-IR camera with this capability. We
determine a gain of 3.8 electrons ADU-1 via a photon transfer analysis and a readout noise of ~27 electrons. A measured
dark current of 0.23 electrons s-1 indicates that the cryostat is extremely light tight. A plate scale of 0.098" pixel-1 results
in a field of view (FOV) of ~3' x 3', which is a compromise between the highest angular resolution achievable and the
largest FOV correctable by WTTM. Measured throughput values (~0.33 in H-band) are consistent with those predicted
for WHIRC based on an elemental analysis. WHIRC was delivered to WIYN in July 2007 and was opened for shared
risk use in Spring 2008. WHIRC will be a facility instrument at the WIYN telescope enabling high definition near-infrared
imaging studies of a wide range of astronomical phenomena including star formation regions, proto-planetary
disks, stellar populations and interstellar medium in nearby galaxies, and supernova and gamma-ray burst searches.
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.
The WIYN High Resolution Infrared Camera (WHIRC) is being developed for use on the WIYN 3.5 m telescope at Kitt Peak. It will mount on a Nasmyth port behind the recently commissioned WIYN Tip-Tilt Module (WTTM). WTTM is expected to routinely deliver 0.25" FWHM images in the near infrared (0.8-2.5 μm), with occasional periods of 0.12" diffraction-limited performance in the K band. WHIRC will take advantage of this superb imaging capability, offering a plate scale of 0.09" per pixel and a 3'x3' field-of-view (FOV) with the planned 2K2 detector. Stringent moment loading requirements at the WTTM interface necessitate a compact, low mass design, which has been achieved using an all-refractive optical path. Tight centering tolerances on the lenses call for precision cryogenic lens assemblies. In this paper we present details of the optical and optomechanical designs, and engineering analyses completed to date.
We present the science case, design overview and sensitivity estimate for the design study for the WIYN High Resolution Infrared Camera (WHIRC). The WIYN telescope is an active 3.5 m telescope located at an excellent seeing site on Kitt Peak and operated by University of Wisconsin, Indiana University, Yale University and National Optical Astronomical Observatory (NOAO). As a dedicated near-infrared (0.8-2.5 micron) camera on the WIYN Tip-Tilt Module (WTTM), WHIRC will provide near diffraction limited imaging, i.e. FWHM~0.25" typically and 0.12" on exceptional nights. The optical design goal is to use a 2048x2048 HgCdTe array with a plate scale of 0.09" per pixel, resulting in a field of view (FOV), 3'x3', which is a compromise between the highest angular resolution achievable and the largest FOV correctable by WTTM. WHIRC will be used for high definition near-infrared imaging studies such as star formation, proto-planetary disks, galactic dust enshrouded B clusters, dust enshrouded stellar populations in nearby galaxies, and supernova and gamma-ray burst searches.