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All sourcesNASA NTRSDOE OSTI
NASA NTRS2012

Overview of the JWST Program

The James Webb Space Telescope (JWST) is a large aperture (6.5 meter), cryogenic space telescope with a suite of near and mid-infrared instruments covering the wavelength range of 0.6 micron to 28 micron. JWST's primary science goal is to detect and characterize the first galaxies. It will also study the assembly of galaxies, star formation, and the formation of evolution of planetary systems. We will review the expected scientific performance of the observatory, and recent technical progress with the observatory and its complement of instruments.

Clampin, M.↗
NASA NTRS2012

Overview of the James Webb Space Telescope

The James Webb Space Telescope (JWST) is a large aperture (6.5 meter), cryogenic space telescope with a suite of near and mid-infrared instruments covering the wavelength range of 0.6 microns to 28 microns. JWST's primary science goal is to detect and characterize the first galaxies. It will also study the assembly of galaxies, star formation, protoplanetary systems, and the formation of evolution of planetary systems. We will review recent progress in the design of JWST' s observatory architecture leading up to JWST's recent Mission Preliminary Design Review (PDR). In particular, we will discuss the status of JWST's optical system, the current status of the telescope mirror fabrication effort, the final design of the observatory sunshield and the plans for integration and test. In this context, we will discuss the expected scientific performance of the observatory.

Clampin, Mark↗
NASA NTRS2008

Performance of the JWST/MIRI Si:As Detectors

The Mid-Infrared Instrument (MIRI) is a 5 to 28 micron imager and spectrometer that is slated to fly aboard the JWST in 2013. Each of the flight arrays is a 1024x1024 pixel Si:As impurity band conductor detector array, developed by Raytheon Vision Systems. JPL, in conjunction with the MIRI science team, has selected the three flight arrays along with their spares. We briefly summarize the development of these devices, then describe the measured performance of the flight arrays along with supplemental data from sister flight-like parts.

arsenic-doped silicon↗
NASA NTRS2014

Recent Progress with the JWST Observatory

The James Webb Space Telescope (JWST) is a large aperture (6.5 meter), cryogenic space telescope with a suite of near and mid-infrared instruments covering the wavelength range of 0.6 micrometers - 28 micrometers. JWST's primary science goal is to detect and characterize the first galaxies. It will also study the assembly of galaxies, star formation, and the formation of evolution of planetary systems. JWST is a segmented mirror telescope operating at (is) approximately 40K, a temperature achieved by passive cooling of the observatory, via a large, 5-layer membrane-based sunshield. We present an overview of the observatory systems design, the science instruments and the mission science objectives. With the completion of the Spacecraft Critical Design Review, the spacecraft has also fully transitioned to fabrication. We will discuss recent highlights associated with the Observatory, including completion and delivery of the primary mirror segments, delivery of the primary mirror backplane and its wings, and the delivery of five template membrane layers. We will also summarize the current predicted performance of the telescope, including stray light, pointing and image quality following the completion of the final design review. Finally, the current schedule through to launch will be presented with a summary of integration and test activities planned when the science payload is delivered to Northrop Grumman following cryo-optical testing at the Johns Space Flight Center.

James Webb Space Telescope (JWST)↗
NASA NTRS2015

Cryogenic Thermal Absorptance Measurements on Small-Diameter Stainless Steel Tubing

The Mid Infrared Instrument (MIRI) on the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 Kelvin operating temperature. The coolant gas flows through several meters of small-diameter stainless steel tubing, which is exposed to thermal radiation from its environment. Over much of its length this tubing is gold-plated to minimize the absorption of this radiant heat. In order to confirm that the cryocooler will meet MIRI's requirements, the thermal absorptance of this tubing was measured as a function of its environment temperature. We describe the measurement technique and present the results.

cryogenics↗
NASA NTRS2017

Cryogenic Thermal Emittance Measurements on Small-Diameter Stainless Steel Tubing

The Mid Infrared Instrument aboard the James Webb Space Telescoep includes a mechanical cryocooler which cools its detectors to their 6 K operating temperature. The refrigerant flows through several meters of approximately 2 mm diameter 304L stainless steel tubing, with some sections gold plated, and some not, which are exposed to their environment. An issue of water freezing onto the tube surfaces is mitigated by a running a warm gas through the lines to sublimate the water. To model the effect of this process on nearby instruments, an accurate measure of the tube emittance is needed. Previously we reported the abosprtance of the gold plated stainless steel tubing as a function of source temperature (i.e. its environment). In this work the thermal emittance of the uncoated tubing is measured as a function of its temperature between 100 and 300 K. This value leads to an accurate prediction of the minimum length of time required to thermally recycle the system. We report the technique and present the results.

cryogenic↗
NASA NTRS2017

Cryogenic Thermal Emittance Measurements on Small-Diameter Stainless Steel Tubing

The Mid Infrared Instrument aboard the James Webb Space Telescope includes a mechanical cryocooler which cools its detectors to their 6 K operating temperature. The refrigerant flows through several meters of 2 mm diameter 304L stainless steel tubing, with some sections gold plated, and some not, which are exposed to their environment. An issue of water freezing onto the tube surfaces is mitigated by running a warm gas through the lines to sublimate the frozen water. To model the effect of this process on nearby instruments, an accurate measure of the tube emittance is needed. Previously we reported the absorptance of the gold plated stainless steel tubing as a function of source temperature (i.e. its environment). In this work the thermal emittance of the uncoated tubing is measured as a function of its temperature between 100 and 280 K. These values lead to an accurate prediction of the minimum length of time required to thermally recycle the system. We report the technique and present the results.

stainless steel↗
NASA NTRS2020

Sensitive Probing of Exoplanetary Oxygen via Mid-Infrared Collisional Absorption

The collision-induced fundamental vibration–rotation band at 6.4 μm is the strongest absorption feature from O2 in the infrared, yet it has not been previously incorporated into exoplanet spectral analyses for several reasons. Either collision-induced absorptions (CIAs) were not included or incomplete/obsolete CIA databases were used. Also, the current version of HITRAN does not include CIAs at 6.4 μm with other collision partners (O2–X). We include O2–X CIA features in our transmission spectroscopy simulations by parameterizing the 6.4-μm O2–N2 CIA based on ref. 3 and the O2–CO2 CIA based on ref. 4. Here we report that the O2–X CIA may be the most detectable O2 feature for transit observations. For a potential TRAPPIST-1 e analogue system within 5 pc of the Sun, it could be the only O2 signature detectable with the James Webb Space Telescope (JWST) (using MIRI LRS (Mid-Infrared Instrument low-resolution spectrometer)) for a modern Earth-like cloudy atmosphere with biological quantities of O2. Also, we show that the 6.4-μm O2–X CIA would be prominent for O2-rich desiccated atmospheres and could be detectable with JWST in just a few transits. For systems beyond 5 pc, this feature could therefore be a powerful discriminator of uninhabited planets with non-biological ‘false-positive’ O2 in their atmospheres, as they would only be detectable at these higher O2 pressures.

Thomas J Fauchez↗
NASA NTRS2019

The Feasibility of Directly Imaging Nearby Cold Jovian Planets with MIRI/JWST

The upcoming launch of the James Webb Space Telescope (JWST) will dramatically increase our understanding of exoplanets, particularly through direct imaging. Microlensing and radial velocity surveys indicate that some M dwarfs host long-period giant planets. Some of these planets will likely be just a few parsecs away and a few astronomical units from their host stars, a parameter space that cannot be probed by existing high-contrast imagers. We studied whether the coronagraphs on the Mid-infrared Instrument on JWST can detect Jovian-type planets around nearby M dwarfs. For a sample of 27 very nearby M dwarfs, we simulated a sample of Saturn–Jupiter-mass planets with three atmospheric configurations and three orbital separations, observed in three different filters. We found that the f1550c 15.5 μm filter is best suited for detecting Jupiter-like planets. Jupiter-like planets with patchy cloud cover, 2 au from their star, are detectable at 15.5 μm around 14 stars in our sample, while Jupiters with clearer atmospheres are detectable around all stars in the sample. Saturns were most detectable at 10.65 and 11.4 μm (f1065c and f1140c filters), but only with cloud-free atmospheres and within 3 pc (six stars). Surveying all 27 stars would take <170 hr of JWST integration time, or just a few hours for a shorter survey of the most favorable targets. There is one potentially detectable known planet in our sample: GJ 832 b. Observations aimed at detecting this planet should occur in 2024–2026, when the planet is maximally separated from the star.

Jonathan Brande↗
NASA NTRS2020

Sensitive Probing of Exoplanetary Oxygen via Mid-Infrared Collisional Absorption

The collision-induced fundamental vibration–rotation band at 6.4 μm is the strongest absorption feature from O2 in the infrared1,2,3, yet it has not been previously incorporated into exoplanet spectral analyses for several reasons. Either collision-induced absorptions (CIAs) were not included or incomplete/obsolete CIA databases were used. Also, the current version of HITRAN does not include CIAs at 6.4 μm with other collision partners (O2–X). We include O2–X CIA features in our transmission spectroscopy simulations by parameterizing the 6.4-μm O2–N2 CIA based on ref. 3 and the O2–CO2 CIA based on ref. 4. Here we report that the O2–X CIA may be the most detectable O2 feature for transit observations. For a potential TRAPPIST-1 e analogue system within 5 pc of the Sun, it could be the only O2 signature detectable with the James Webb Space Telescope (JWST) (using MIRI LRS (Mid-Infrared Instrument low-resolution spectrometer)) for a modern Earth-like cloudy atmosphere with biological quantities of O2. Also, we show that the 6.4-μm O2–X CIA would be prominent for O2-rich desiccated atmospheres5 and could be detectable with JWST in just a few transits. For systems beyond 5 pc, this feature could therefore be a powerful discriminator of uninhabited planets with non-biological ‘false-positive’ O2 in their atmospheres, as they would only be detectable at these higher O2 pressures.

Thomas Fauchez↗
NASA NTRS2022

Nested Dust Shells Around the Wolf–Rayet Binary WR 140 Observed With JWST

Massive colliding-wind binaries that host a Wolf–Rayet (WR) star present a potentially important source of dust and chemical enrichment in the interstellar medium. However, the chemical composition and survival of dust formed from such systems is not well understood. The carbon-rich Wolf–Rayet binary WR 140 presents an ideal astrophysical laboratory for investigating these questions, given its well-defined orbital period and predictable dust-formation episodes every 7.93 years around periastron passage. We present observations from our Early Release Science programme (ERS 1349) with the James Webb Space Telescope Mid-Infrared Instrument (MIRI) Medium-Resolution Spectrometer and Imager that reveal the spectral and spatial signatures of nested circumstellar dust shells around WR 140. MIRI medium-resolution spectroscopy of the second dust shell and Imager detections of over 17 shells formed throughout approximately the past 130 years confirm the survival of carbonaceous dust grains from WR 140 that are probably carriers of ‘unidentified infrared’-band features at 6.4 and 7.7 μm. The observations indicate that dust-forming carbon-rich Wolf–Rayet binaries can enrich the interstellar medium with organic compounds and carbonaceous dust.

massive stars↗
NASA NTRS2019

The Origins Space Telescope

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 cryo cooled 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 background limited sensitivity.

Leisawitz, D.↗
NASA NTRS2017

Characterization of Si-Membrane TES Bolometer Arrays for the HIRMES Instrument

The High Resolution Mid-Infrared Spectrometer (HIRMES) instrument will fly onboard NASA's airborne Stratospheric Observatory for Infrared Astronomy (SOFIA) in 2019. HIRMES will provide astronomers with a unique observing window (25 122 µm) for exploring the evolution of protoplanetary disks into young solar systems, and the composition of our Solar System. There are two focal plane detector arrays for the instrument: a high-resolution (/ = 100,000) 8x16 detector array with a target noise-equivalent power, NEP 3x10-18 W/Hz; and a low-resolution (/ = 2,000 19,000) 16x64 detector array with a target NEP 2x10-17 W/Hz. The detectors for both of these arrays are superconducting Mo/Au bilayer transition edge sensor (TES) bolometers on thin suspended single-crystal silicon membranes. Here we present our characterization results for the detectors in both arrays, including measurements of thermal conductance with comparison to phonon transport models, saturation power, noise, and array uniformity.

Instrumentation and Photography↗
NASA NTRS2005

Development of mid-IR lasers for Laser Remote Sensing

There is an existing need in JPL and in NASA for development of mid-IR lasers, such as Quantum Cascade (QC) lasers, for in-situ and remote laser spectrometers. Mid-IR, compact, low power consumption laser spectrometers have a great potential for detection and measurements of planetary gases and biological important biomarker molecules such as H20, H202, CH4, and many additional chemical species on Mars and other Solar system planets. Another potential application of QC lasers for future NASA mission is in high power remote Laser Reflectance Spectrometers (LRS). In LSR instrument, mid-infrared lasers will act as the illumination source for conducting active mid-IR reflectance spectroscopy of solid-surfaced objects in the outer Solar System. These spectrometers have the potential to provide an incredible amount of information about the compositions of surfaces in the outer Solar System. In this work, we will discuss our current effort at JPL to advance QC lasers to a level that the laser performance, operational requirements and reliability be compatible with the instruments demands for space exploration applications.

Mid - IR lasers↗
NASA NTRS2021

VLTI-MATISSE Chromatic Aperture-Synthesis Imaging of η Carinae’s Stellar Wind Across the Brα Line: Periastron Passage Observations in February 2020

Context: Eta Carinae is a highly eccentric, massive binary system (semimajor axis∼15.5 au) with powerful stellar winds and a phase-dependent wind-wind collision (WWC) zone. The primary star, ηCar A, is a luminous blue variable (LBV); the secondary, η Car B, is a Wolf-Rayet or O star with a faster but less dense wind. Aperture-synthesis imaging allows us to study the mass loss from the enigmatic LBV η Car. Understanding LBVs is a crucial step toward improving our knowledge about massive stars and their evolution. Aims: Our aim is to study the intensity distribution and kinematics of η Car’s WWC zone. Methods: Using the VLTI-MATISSE mid-infrared interferometry instrument, we perform Brα imaging of η Car’s distorted wind. Results: We present the first VLTI-MATISSE aperture-synthesis images of η Car A’s stellar wind in several spectral channels distributed across the Brα 4.052 μm line (spectral resolving power R∼960). Our observations were performed close to periastron passage in February 2020 (orbital phase∼14.0022). The reconstructed iso-velocity images show the dependence of the primary stellar wind on wavelength or line-of-sight (LOS) velocity with a spatial resolution of 6 mas (∼14 au). The radius of the faintest outer wind regions is∼26 mas (∼60 au). At several negative LOS velocities, the primary stellar wind is less extended to the northwest than in other directions. This asymmetry is most likely caused by the WWC. Therefore, we see both the velocity field of the undisturbed primary wind and the WWC cavity. In continuum spectral channels, the primary star wind is more compact than in line channels. A fit of the observed continuum visibilities with the visibilities of a stellar wind CMFGEN model (CMFGEN is an atmosphere code developed to model the spectra of a variety of objects) provides a full width at half maximum fit diameter of the primary stellar wind of 2.84±0.06 mas (6.54±0.14 au). We compare the derived intensity distributions with the CMFGEN stellar wind model and hydrodynamic WWC models.

G Weigelt↗
NASA NTRS2020

Mid-infrared detector development for the Origins Space Telescope

Mid-infrared detector arrays operating from 2.8 to 20 μm are baselined in the design of the Origins Space Telescope Mid-Infrared Spectrometer Instrument. This instrument is designed to detect and measure the spectral signatures of gases of biogenic origin in the atmospheres of exoplanets as they transit their host stars. In order to make these detections, the detector array’s pixels need to have high-signal stability when exposed to a constant flux in multiple time-series integration over a typical transit time of a few hours. With the use of a densified pupil spectrometer design, pointing effects can be mitigated because pointing variations do not displace spectra on the detector and each wavelength of light is averaged over a large number of pixels, giving good spectrophotometric stabilities. The current state-of-the-art detector arrays do not achieve these stabilities, although with a feasible development program this level of performance should be achievable. Three detector technologies are under consideration for this development, HgCdTe arrays, Si:As impurity band conduction arrays, and transition edge super-conductor bolometer arrays. We primarily treat the HgCdTe technology development, but also introduce the paths forward for the other two technologies. After a few years-long investigative programs, a down-select will be undertaken to select the flight technology.

Astronomy↗