We are developing the Background-Limited Infrared-Submillimeter Spectrograph (BLISS) for SPICA to provide
a breakthrough capability for far-IR survey spectroscopy. SPICAs large cold aperture allows mid-IR to submm
observations which are limited only by the natural backgrounds, and BLISS is designed to operate near this
fundamental limit. BLISS-SPICA is 6 orders of magnitude faster than the spectrometers on Herschel and
SOFIA in obtaining full-band spectra. It enables spectroscopy of dust-obscured galaxies at all epochs back to
the rst billion years after the Big Bang (redshift 6), and study of all stages of planet formation in circumstellar
BLISS covers 35 - 433 microns range in ve or six wavelength bands, and couples two 2 sky positions simultaneously.
The instrument is cooled to 50 mK for optimal sensitivity with an on-board refrigerators. The detector
package is 4224 silicon-nitride micro-mesh leg-isolated bolometers with superconducting transition-edge-sensed
(TES) thermistors, read out with a cryogenic time-domain multiplexer. All technical elements of BLISS have
heritage in mature scientic instruments, and many have own. We report on our design study in which we are
optimizing performance while accommodating SPICAs constraints, including the stringent cryogenic mass budget.
In particular, we present our progress in the optical design and waveguide spectrometer prototyping. A
companion paper in Conference 7741 (Beyer et al.) discusses in greater detail the progress in the BLISS TES
CALISTO, the Cryogenic Aperture Large Infrared Space Telescope Observatory, will enable extraordinarily high
sensitivity far-infrared continuum and moderate (R ~ 1000) resolution spectroscopic observations at wavelengths from
~30µm to ~300 μm - the wavelengths between those accessible by JWST and future ground based facilities.
CALISTO's observations will provide vital information about a wide range of important astronomical questions
including (1) the first stars and initial heavy element production in the universe; (2) structures in the universe traced by
H2 emission; (3) the evolution of galaxies and the star formation within them (4) the formation of planetary systems
through observations of protostellar and debris disks; (5) the outermost portions of our solar system through observations
of Trans-Neptunian Objects (TNOs) and the Oort cloud. With optics cooled to below 5 K, the photon fluctuations from
the astronomical background (Zodiacal, Galactic, and extragalactic) exceed those from the telescope. Detectors with a
noise equivalent power below that set by the background will make possible astronomical-background-limited sensitivity
through the submillimeter/far-infrared region. CALISTO builds on studies for the SAFIR (Single Aperture Far Infrared)
telescope mission, employing a 4m x 6m off-axis Gregorian telescope which has a simple deployment using an Atlas V
launch vehicle. The unblocked telescope with a cold stop has minimal sidelobes and scattering. The clean beam will
allow astronomical background limited observations over a large fraction of the sky, which is what is required to achieve
CALISTO's exciting science goals. The maximum angular resolution varies from 1.2" at 30 µm to 12" at 300 μm. The
5σ 1 hr detectable fluxes are ▵S(dν/ν = 1.0) = 2.2x10-20 Wm-2, and ▵S(dν/ν = 0.001) = 6.2x10-22 Wm-2. The 8 beams per
source confusion limit at 70 μm is estimated to be 5 μJy. We discuss CALISTO optics, performance, instrument
complement, and mission design, and give an overview of key science goals and required technology development to
enable this promising far IR/submm mission.
The Single Aperture Far Infrared (SAFIR) observatory - a concept design for a 10m-class spaceborne far- infrared and
submillimeter telescope, has been proposed for development, and given high priority by agency strategic planners.
SAFIR will target star formation in the early universe, the chemistry of our interstellar medium, and the chemical
processes that lead to planet formation. SAFIR is a telescope that, with passive cooling at Earth-Sun L2, achieves
temperatures that allow background-limited broad-band operation in the far infrared. This observatory is baselined as
being autonomous in deployment and operation, but consideration has been given to understanding the enabling
opportunities presented by Exploration architecture. As this architecture has become better defined, these opportunities
have become easier to understand.We present conceptual strategies that would use modestly enhanced Exploration
architecture to service and maintain SAFIR, allowing extended duration, lower risk and hardware cost, and performance
enhancements linked to the steep development curve for sensor technology. These efforts, which would rely on both
human and robotic agents, presume routine operations at Earth-Sun L2, and servicing at an Earth-Moon L1 jobsite. The
latter is understood to be easily accessible to a lunar-capable Exploration program. This study bridges the interface
between Exploration technology and astronomical space observatory technology. Such an Exploration-enhanced version
of SAFIR can be seen as a strawman for more ambitious far future work, in which much larger science instruments that
cannot be packaged in a single launch vehicle are not only serviced and maintained in space, but also constructed there.
We report on completion of the SAFIR Vision Mission study, as organized by the NASA Science Mission Directorate.
This study resulted in a focused baseline design for this large aperture space observatory that capitalizes on architectures
being actively developed for JWST and other missions. Special opportunities for achieving thermal performance of this
<10 K telescope are reviewed, as well as efforts to understand capabilities and needs for focal plane instrument and I and T
on this large (10 m-class) telescope.
The Single Aperture Far Infrared (SAFIR) observatory is a high priority mission for NASA and space astronomy. This ten-meter diameter telescope, operating at <10 Kelvin, will chart the formation of galaxies and elements in the early universe, map debris disks around stars to track hidden planets, and explore the chemistry of life in the universe. While baselined as an autonomously deployed telescope, we consider enabling factors that in-space operations would bring to this telescope - in particular, servicing opportunities that would dramatically increase the scientific lifetime and productivity of the observatory. The use of humans and robots to support and conduct servicing, at the operational site of Earth-Sun L2 and primarily at Earth-Moon L1, are considered, and the required capabilities are reviewed. SAFIR shares many characteristics of future large telescopes in space, and strategies developed for this strawman case are applicable for broader planning efforts.
SAFIR is a large (10 m-class), cold (4-10 K) space telescope for wavelengths between 20 microns and 1 mm. It will provide sensitivity a factor of a hundred or more greater than that of Spitzer and Herschel, leveraging their capabilities and building on their scientific legacies. Covering this scientifically critical wavelength regime, it will complement the expected wavelength performance of the future flagship endeavors JWST and ALMA. This vision mission will probe the origin of stars and galaxies in the early universe, and explore the formation of solar systems around nearby young stars. Endorsed as a priority by the Decadal Study and successive OSS roadmaps, SAFIR represents a huge science need that is matched by promising and innovative technologies that will allow us to satisfy it. In exercising those technologies it will create the path for future infrared missions. This paper reviews the scientific goals of the mission and promising approaches for its architecture, and considers remaining technological hurdles. We review how SAFIR responds to the scientific challenges in the OSS Strategic Plan, and how the observatory can be brought within technological reach.
Development of large, far-infrared telescopes in space has taken on a new urgency with breakthroughs in detector technology and recognition of the fundamental importance of the far-infrared spectral region to cosmological questions as well as to understanding how our own Solar System came into being. SAFIR is 10m-class far-infrared observatory that would begin development later in this decade to meet these needs. Its operating temperature (T ≤ 4 K) and instrument complement would be optimized to reach the natural sky confusion limit in the far-infrared with diffraction-limited peformance down to at least the atmospheric cutoff, λ ⪆ 40 μm. This would provide a point source sensitivity improvement of several orders of magnitude over that of SIRTF. SAFIR's science goals are driven by the fact that youngest stages of almost all phenomena in the universe are shrouded in absorption by and emission from cool dust that emits strongly in the far-infrared, 20 μm - 1mm. The main drivers on the telescope are operating temperature and aperture. SAFIR can take advantage of much of the technology under development for NGST. Because of the much less stringent requirements on optical accuracy, however, SAFIR can be developed at substantially lower cost.
We discuss plans for the construction of a 15-m class telescope located in the high Atacama desert of Northern Chile. The baseline concept is a segmented mirror telescope optimized for operation at wavelengths longer than 3.5 microns but capable of working at shorter wavelengths. An adaptive secondary will be used to achieve diffraction limited imaging while maintaining low emissivity. The facility will be designed for eventual remote/robotic operation and include a number of instruments designed to take advantage of the low precipitable water vapor and good seeing conditions.