We have conducted a set of experiments on a TES (Transition-Edge Superconductor) bolometer detector array, demonstrating that a flux measurement stability better than 5 parts per million (ppm) over periods of hours to days, can be achieved with modest thermal stability requirements. This level of measurement stability is critical in enabling measurements of the atmospheric signatures of terrestrial-sized exoplanets around nearby K and M stars, including those in the star's habitable zone. The demonstration uses a simple tungsten filament light bulb as the source, a photo diode operating at 0.5 mu m as a stability monitor for the light bulb, and a grating spectrometer in the 5-15 mu m wavelength range.

The PRime-focus Infrared Microlensing Experiments (PRIME) camera is part of the joint NASA-JAXA project supporting the Nancy Grace Roman Space Telescope engineering and science studies. It is installed on the 1.8 m PRIME telescope with a approximate to 1.5 square degree FOV dedicated to the project. The instrument is equipped with multiple broad band and narrow band filters between 0.9 mu m to 1.8 mu m. The instrument is installed at the South African Astronomical Observatory and has been in continuous operation since October 2022. PRIME is currently surveying the Galactic bulge for microlensing events, GW and GRB studies and other science objectives, in advance of the Roman Space Telescope (RST) mission. After 1.5 years of on-sky operation, we present the use, performance and lessons learned operating RST's yield demonstration lot H4RG-10 detectors as part of the PRIME camera based on the data processing and analysis tools that we have developed. With the large field of view in the near infrared bands this instrument is a powerful tool in the Southern hemisphere and a compliment to the instruments in the North and in the visible.

We present recent progress in the development of ultra-low-noise Transition-Edge Sensors (TESs) pixels designed for far-infrared (~30-300µm) astronomical instruments. The TES sensitivity is maximized using phononic filters, which are sub-wavelength coherent filters that provide broadband rejection of thermal phonons emitted at the TES critical temperature, Tc~100mK. The phononic filter isolation legs are compact, ~50 µm. In a absorber-coupled bolometer suspended by four legs, the thermal conductance is reduced to achieve an NEP of less than 0.3 aW/rtHz, which is sufficient for balloon- and space-based imaging and low-resolution spectrometer instruments with cold optics. We discuss the phononic filter and TES design, the performance of the phononic-isolated TES pixels, and the advantage of these highly-sensitive absorber-coupled TES bolometers for astronomical instruments.

We have obtained NASA funding to build and demonstrate Transition Edge Sensor (TES) based kilopixel arrays with the properties that match the requirements for cryogenic far-infrared space missions: the arrays are very closely tileable in one direction and have only a moderate gap in the other direction. This array architecture can meet the sampling- and pixel number requirement of similar to 10(4) pixels. Many details of the architecture have already been demonstrated individually, and the detector board will be optimized for the use of the latest cryogenic bump bonded NIST 2-D time domain SQUID readout multiplexers with a high density fanout scheme. Additionally, we use flex-lines that are very similar to those developed at Princeton University for the ACT project. We already have a pixel design that exceeds the continuum sensitivity requirements for a cryogenic space mission.

The Astrophysics 2020 Decadal Report recommended a line of Probe missions with far-infrared imaging or spectroscopy capabilities. The achievable sensitivity of these FIR missions will be enabled by cooled telescopes and advanced cryogenic detector technologies, potentially resulting in up to three orders of magnitude improvement in sensitivity and mapping speeds up to more than a million times of those achieved so far with past missions. We have obtained NASA funding to build and demonstrate transition edge sensor (TES)-based kilopixel arrays with the properties that match the requirements for cryogenic far-infrared space missions: The arrays are very closely tileable in one direction and with a moderate gap in the other direction. This array architecture can meet the sampling and pixel number requirement of a few 104 pixels. Many details of the architecture have already been demonstrated individually, and the detector board will be optimized for the use of the latest cryogenic NIST 2D time-domain SQUID readout multiplexers with a high-density fanout scheme. Additionally, we will use flex lines that are very similar to those developed at Princeton University for the ACT project. This method allows virtually unlimited tileability of the detector arrays and thus a compact detector/readout design for future FIR instrumentation requiring large pixel counts. We already have a pixel design which, if implemented with TES operating at less than 100 mK, will meet the continuum sensitivity requirements for background-limited cryogenic space missions of NEP < 10–18 W/√Hz). Furthermore, our array design will be compatible with lower noise TES designs for spectroscopy that we are currently demonstrating in our laboratory.

We have built an ultra-stable laboratory spectrometer, called MIRASET (Mid-IR Array Spectrometer demonstration for Exoplanet Transits), that will demonstrate a new method to extract mid-infrared spectral lines observed in the atmospheres of transiting planets around M-stars. Those lines potentially indicate the presence of life on the planet. This goal is achieved by using a black body source as a calibration reference, which in the laboratory experiment also simulates the emission of the M-star. The black body emission source will be tuned to dissipate the equivalent power on the detectors that would be observed from Proxima Cen B and Trappist-1 if they were observed with a space-based observatory such as ORIGINS or a dedicated MIR exoplanet mission such as MIRECLE. Furthermore, we use a laser that simulates a spectral line from the planet. We constantly monitor the temperature of the black body with high precision by using a photodiode measuring the black body in the visible. We will demonstrate the ability to monitor the black body emission over a several hour period, superimposed with a laser-generated spectral line, down to a photometric precision of 5ppm, while demonstrating the spectral stability of the spectrometer. This precision constitutes the requirement for the detection of important atmospheric lines from earth-like planets around M-stars

The PRime-focus Infrared Microlensing Experiment (PRIME) camera is part of the joint NASA-JAXA project in support of the spaceflight Roman Space Telescope project development. It is designed to accommodate the needs of the large-scale survey of the microlensing events in the Galactic bulge. The camera is placed in the prime focus of the 1.8-m telescope dedicated to this project. With four large-format infrared detectors, the instrument covers a field of view about 1.3 square degrees. Over the few years preceding and during the operations of the Roman Space Telescope, the instrument will be used for continuous monitoring of selected fields in the Galactic bulge for microlensing events and a number of other science programs of the consortium.

Electrothermal feedback in a transition edge sensor (TES) suppresses thermal fluctuations in the TES and well-thermally coupled regions in proximity. We have designed a heavily metallized, leg-isolated membrane with a TES which serves as a thermal isolation stage that can be lithographically integrated with other devices, for example, a suitably designed TES detector. Through modeling, fabrication, and test of prototype devices, we plan to examine the utility of stabilizing this guard stage to limit low frequency variability in the sensor response. In one implementation, a leg-isolated TES bolometer of higher superconducting transition temperature (T-c) is encircled by a second membrane region which is metallized and thermally stabilized by a second, lower-T-c TES. We present fabrication results on the dual-T-c device and explore varied heat capacity of the thermal stability stage in the single-pixel design. We then evaluate the use of this stage for multiple pixel arrangements and investigate the criteria for stabilizing such a device.

We report on efforts to improve the speed of low-G far-infrared transition-edged-sensed bolometers. We use a fabrication process that does not require any dry etch steps to reduce heat capacity on the suspended device and measure a reduction in the detector time constant. However, we also measure an increase in the temperature-normalized thermal conductance (G) and a corresponding increase in the noise-equivalent power (NEP). We employ a new near-IR photon-noise technique using a near-IR laser to calibrate the frequency-domain multiplexed AC system and compare the results to a well-understood DC circuit. We measure an NEP white noise level of 0.8 aW/rtHz with a 1/f knee below 0.1 Hz and a time constant of 3.2 ms.

The far-infrared (FIR) band is uniquely suited to study the physical conditions in the interstellar medium and star formation out to the highest redshifts. Robust, high sensitivity detector arrays that operate over the entire FIR regime with up to several 10(4) pixels, large focal plane filling factors and compatibility with low noise detector designs and low cosmic ray cross sections, are required for future (F)IR missions, such as Origins. The arrays could consist of smaller sub-arrays, since they can be tiled. The GSFC-designed Backshort Under Grid (BUG) array architecture and its precursor architectures have been fielded in several FIR cameras, including GISMO at the IRAM 30 m telescope (the array used in this instrument was strictly speaking a precursor to the final BUG array) and HAWC + on SOFIA. The BUG array used in the latter instruments has an integrated termination board and SQUID readout multiplexer. The array was fabricated in collaboration between NASA/GSFC and NIST and meets these requirements. However, the BUG fabrication has many low throughput processing steps, with the consequence of long production times and sub-optimal yields. To meet the requirements for robustness and production efficiency for future arrays, we have developed, and by now partially demonstrated, a new architecture to provide the superconducting connection of transition edge sensor detectors to the readout multiplexers or readout boards behind the array. This approach will allow us to reach the goal to produce reliable, large low noise detector arrays for future space-based and suborbital instrumentation.

The balloon-borne Japan-United States Infrared Interferometry Experiment (JUStIInE) is a pathfinder for the first space-based far-IR interferometer. JUStIInE will mature the system-level technology readiness of spatio-spectral far-IR interferometry and demonstrate this technique with scientific observations. Operating at wavelengths from 30 to 90 µm, JUStIInE will provide unprecedented sub-arcsecond angular resolution and spectroscopic data. Our plan is to develop a cryogenic Michelson beam combiner and integrate it with an existing and tested telescope optical system and gondola from the Japanese Far-infrared Interferometric Telescope Experiment (FITE). With two JUStIInE balloon flights we plan to collect, calibrate, analyze, and publish scientific results based on the first far-IR spatio-spectral observations of young stellar objects, evolved stars, and the active galactic nucleus of NGC 1068. The NASA Astrophysics Roadmap envisages a future in which interferometry is applied across the electromagnetic spectrum, starting in the far-infrared. The Far-IR Probe recommended in the 2021 Decadal Survey presents an opportunity to take that important step. A Far-IR Probe mission based on this concept will enable us to understand terrestrial planet formation and spectroscopically study individual distant galaxies to understand the astrophysical processes that govern their evolution.

Superconducting Transition Edge Sensor (TES) bolometer arrays with thousands of pixels are essential for achieving the science objectives of future cold far-infrared astronomical telescopes. The readout of such large format TES arrays represents a significant challenge for these missions in terms of power consumption and thermal loading on the coldest cryogenic stages of the instruments. The Time Domain Multiplexing (TDM) technology is mature and has been implemented on many ground-based and air-borne instruments using TES arrays. Several concept studies such as Origins Space Telescope (OST [4]) or Mid-InfraRed Exo-planet CLimate Explorer (MIRECLE [5]) consider this technology and Time Domain Multiplexing as one of the possible baseline technologies for their instruments. In order to address the aforementioned challenges we propose a novel modular solution called Modular Adaptive Transition Edge Sensor Superconducting quantum interference device Electronics (MATESSE) that will serve as the necessary step towards an adaptation of the solution to a space-proven system.

The discovery of the Trappist-1 system, which consists of an ultra cool M-dwarf star orbited by 7 planets, 3 of which are located in the habitable zone, has demonstrated that these types of planetary systems around dwarf stars are very common. Such systems are well suited for the study of exoplanets. In particular the search for bio-signatures in the atmosphere of planets in the habitable zone around M-stars will be a high-priority science goal of future space missions. The mid-infrared (mid-IR) band between 3 and 15 microns is probably the best available band for this science, because the spectral lines of methane, ozone, and nitrous oxide can be found in this spectral range. he coexistence of these constituents in a planets atmosphere would be a very strong indicator for life on the planet. Mid-IR transit spectrometers on future space missions such as Origins Space Telescope (OST) will be the instrument of choice to detect these bio-signatures in exoplanets around M-dwarfs. Current mid-IR detectors are based on impurity band conduction (IBC) devices such as Si: As detectors. Charge trapping in these device leads to a time and exposure dependent response. As a result, this detector class is not expected to provide the required 5 ppm stability needed for a reliable detection of the aforementioned spectral lines. While efforts are under way to improve IBC detectors, it is un-clear how far the performance can be improved. Here we describe the development of an ultra-stable Mid-IR Array Spectrometer demonstration for Exoplanet Transits (MI-RASET), which includes a calibration system that, as we show, is needed to achieve the required sensitivity for the detection of atmospheric bio-signatures in habitable-zone planets around M-dwarfs. The spectrometer will be demonstrated with arrays of Transition Edge Sensor detectors (TES). These devices are known to have a very linear response and are intrinsically very stable. Furthermore, the required detector parameters (sensitivity, dynamic range) for space based mid-IR transit spectroscopy can be easily met with existing devices. No new detector developments are required, only the absorbers need to be optimized for the wavelength range of the instrument. This project will include the development of a high-accuracy calibration system with a stable reference source which itself will be monitored in the visible (0.5μm) by a photo diode. At this wavelength the precision of the load temperature measurement exceeds that of an in-band calibration. This scheme will allow for real time monitoring of the detector gain and offset, which we anticipate will result in a background limited performance with the required stability of better than 5 ppm for the detection of bio-signatures in a designated spectrometer flying e.g. on the OST space telescope, and as such will help to answer one of NASA's prime questions: “Are we alone?”.

This White Paper presents a mission concept called MIRECLE - the Mid-InfraRed Exoplanet CLimate Explorer. With a moderately sized aperture of 2 meters, broad wavelength coverage (4 - 25 um), and next generation instruments, MIRECLE will be capable of efficiently characterizing a statistically significant sample of terrestrial planets, many of which will be in their host stars's habitable zones. Spectroscopic characterization of terrestrial atmospheres will provide constraints for the distribution of planets with tenuous vs. substantial atmospheres, on the inner and outer edges of the habitable zone, and climate models to assess the potential for habitability. For the few brightest targets, the detection of specific combinations of molecules would provide evidence of biosignatures. For all other targets, this comprehensive survey would filter out the airless, desiccated, or lifeless worlds, thus providing a subset of potentially habitable worlds ready for in-depth atmospheric characterization using a larger aperture telescope.

The Primordial Inflation Polarization Explorer (PIPER) is a balloon-borne telescope mission to search for inflationary gravitational waves from the early universe. PIPER employs two 32 × 40 arrays of superconducting transition-edge sensors, which operate at 100 mK. An open bucket Dewar of liquid helium maintains the receiver and telescope optics at 1.7 K. We describe the thermal design of the receiver and sub-Kelvin cooling with a continuous adiabatic demagnetization refrigerator (CADR). The CADR operates between 70 and 130 mK and provides ≈10 μW cooling power at 100 mK, nearly five times the loading of the two detector assemblies. We describe electronics and software to robustly control the CADR, overall CADR performance in flightlike integrated receiver testing, and practical considerations for implementation in the balloon float environment.

We propose a high precision calibration scheme for a Mid-IR Exoplanet Spectrometer. This new technology will enable high-precision transmission, emission, and phase curve spectroscopy for the characterization of exoplanets in and near the habitable zone, enabling the detection of biosignatures in rocky planets around the nearest M dwarfs.

The Balloon Experimental Twin Telescope for Infrared Interferometry (BETTII) mission launched from Palestine, Texas in June 2017. After an exciting launch and successful cruise, the BETTII gondola suffered an anomalous event at termination. BETTII separated from its parachute and free-fell 136,000 feet into the west Texas desert. This event was classified as a "close-call" and investigated as such. We present here the recovery effort required to find the payload and extract the payload from its impact site. We also present lessons learned from the event and results from the investigation, the design for the next BETTII gondola, and a path forward for return to flight.

The HIgh-Resolution Mid-infrarEd Spectrometer (HIRMES) is the 3rd Generation Instrument for the Stratospheric Observatory For Infrared Astronomy (SOFIA), currently in development at the NASA Goddard Space Flight Center (GSFC), and due for commissioning in 2019. By combining direct-detection Transition Edge Sensor (TES) bolometer arrays, grating-dispersive spectroscopy, and a host of Fabry-Perot tunable filters, HIRMES will provide the ability for high resolution ([Formula: see text]), mid-resolution ([Formula: see text]), and low-resolution ([Formula: see text]) slit-spectroscopy, and 2D Spectral Imaging ([Formula: see text] at selected wavelengths) over the 25–122[Formula: see text][Formula: see text]m mid to far infrared waveband. The driving science application is the evolution of proto-planetary systems via measurements of water-vapor, water-ice, deuterated hydrogen (HD), and neutral oxygen lines. However, HIRMES has been designed to be as flexible as possible to cover a wide range of science cases that fall within its phase-space, all whilst reaching sensitivities and observing powers not yet seen thus far on SOFIA, providing unique observing capabilities which will remain unmatched for decades.