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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Lessons for WFIRST CGI from Ground-Based High-Contrast Systems

The Coronagraph Instrument (CGI) for NASA’s Wide Field Infrared Survey Telescope (WFIRST) will constitute a dramatic step forward for high-contrast imaging, integral field spectroscopy, and polarimetry of exoplanets and circumstellar disks, aiming to improve upon the sensitivity of current ground-based direct imaging facilities by 2–3 orders of magnitude. Furthermore, CGI will serve as a pathfinder for future exo-Earth imaging and characterization missions by demonstrating wavefront control, coronagraphy, and spectral retrieval in a new contrast regime, and by validating instrument and telescope models at unprecedented levels of precision. To achieve this jump in performance, it is critical to draw on the experience of ground-based high-contrast facilities. We discuss several areas of relevant commonalities, including: wavefront control, post-processing of integral field unit data, and calibration and observing strategies.

Xuan, Wenhao↗
NASA NTRS2019

KELT-24b: A 5M(J) Planet on a 5.6 day Well-aligned Orbit around the Young V=8.3 F-star HD 93148

We present the discovery of KELT-24 b, a massive hot Jupiter orbiting a bright (V=8.3 mag, K=7.2 mag) young F-star with a period of 5.6 days. The host star, KELT-24 (HD 93148), has a Teff=-+65094950K, a mass of M*=+1.4600.0590.055Me, a radius of R*=1.506±0.022Re, and an age of +0.780.420.61Gyr. Its planetary companion (KELT-24 b) has a radius of RP=1.272±0.021RJ and a mass of MP=-+5.180.220.21MJ, and from Doppler tomographic observations, we find that the planet’s orbit is well aligned to its host star’s projected spin axis (l=-+2.63.65.1). The young age estimated for KELT-24 suggests that it only recently started to evolve from the zero-age main sequence. KELT-24 is the brightest star known to host a transiting giant planet with a period between 5 and 10 days. Although the circularization timescale is much longer than the age of the system, we do not detect a large eccentricity or significant misalignment that is expected from dynamical migration. The brightness of its host star and its moderate surface gravity make KELT-24b an intriguing target for detailed atmospheric characterization through spectroscopic emission measurements since it would bridge the current literature results that have primarily focused on lower mass hot Jupiters and a few brown dwarfs.

Transit photometry↗
NASA NTRS2020

KELT-25 b and KELT-26 b: A Hot Jupiter and a Substellar Companion Transiting Young A Stars Observed by TESS

We present the discoveries of KELT-25 b (TIC 65412605, TOI-626.01) and KELT-26 b (TIC 160708862, TOI-1337.01), two transiting companions orbiting relatively bright, early A stars. The transit signals were initially detected by the KELT survey and subsequently confirmed by Transiting Exoplanet Survey Satellite (TESS) photometry. KELT-25 b is on a 4.40 day orbit around the V=9.66 star CD-24 5016(=-+T8280eff180440K,Må=-+2.180.110.12Me), while KELT-26 b is on a 3.34 day orbit around the V=9.95 star HD 134004 (Teff=-+8640240500K,Må=-+1.930.160.14Me), which is likely an Am star. We have confirmed the substellar nature of both companions through detailed characterization of each system using ground-based and TESS photometry, radial velocity measurements, Doppler tomography, and high-resolution imaging. For KELT-25, we determine a companion radius of RP=-+1.640.0430.039RJ and a 3σupper limit on the companion’s mass of64MJ. For KELT-26 b, we infer a planetary mass and radius of MP=-+1.410.510.43MJ and RP=-+1.940.0580.060RJ. From Doppler tomographic observations, we find KELT-26 b to reside in a highly misaligned orbit. This conclusion is weakly corroborated by a subtle asymmetry in the transit light curve from the TESS data. KELT-25 b appears to be in a well-aligned, prograde orbit, and the system is likely a member of the cluster Theia 449.

Exoplanet astronomy↗
NASA NTRS2021

In Situ Performance of the Low Frequency Array for Advanced ACTPol

The Advanced Atacama Cosmology Telescope Polarimeter (AdvACT) is an upgrade for the Atacama Cosmology Telescope using Transition Edge Sensor (TES) detector arrays to measure cosmic microwave background (CMB) temperature and polarization anisotropies in multiple frequencies. The low frequency (LF) array was deployed early 2020. It consists of 292 TES bolometers observing in two bands centered at 27 GHz and 39 GHz. At these frequencies, it is sensitive to synchrotron radiation from our galaxy as well as to the CMB, and complements the AdvACT arrays operating at 90, 150 and 230 GHz. We present the initial LF array on-site characterization, including the time constant, optical efficiency and array sensitivity.

Superconducting detectors↗
NASA NTRSDate not supplied

Operating and Maintaining the JWST Cleanroom attached to JSC's Chamber A during preparations for the OTIS Cryogenic Thermal Vacuum Test

In order to maintain cleanliness during preparations for JWST’s OTIS (Optical Telescope Element-Integrated Science Instrument Module) Cryogenic Thermal Vacuum Test, a cleanroom was built that attached directly to the 60-year-old Chamber A. The cleanroom and chamber were outfitted with independent environmental control systems each providing ISO Class 71 air cleanliness. To maintain balanced, positive pressure in both the cleanroom and chamber volumes, a special control protocol was developed and successfully implemented. Dual back-up environmental control units (one each for the chamber and cleanroom) were installed just outside the building to provide environmental control redundancy due to a single source chilled water supply and weather threats. In addition, lack of a dedicated cleanroom airlock facilitating clean ingress and egress made it necessary to perform additional cleaning and packaging, as well as augment the uncontrolled truck lock space with small clean tents for pre-cleaning. Special procedures were developed to allow ingress of extra-large support equipment required for load testing of the cleanroom crane, installation of optical equipment in Chamber A and accommodation of the OTIS shipping container. A thorough bake-out and cleaning of Chamber A was also necessary to reduce volatiles from the shroud’s black thermal paint and to reduce particle fallout. Acrylic adhesive fracture discovered during early cryo-testing represented a significant challenge that was successfully mitigated prior to OTIS testing. A dedicated team of Contamination Control (CC) Technicians was specifically trained to clean support equipment and screen materials entering the cleanroom and chamber to ensure cleanliness and vacuum compatibility.

Optics↗
NASA NTRSDate not supplied

Operating and Maintaining the JWST Cleanroom attached to JSC's Chamber A during preparations for the OTIS Cryogenic Thermal Vacuum Test

In order to maintain cleanliness during preparations for JWST’s OTIS (Optical Telescope Element-Integrated Science Instrument Module) Cryogenic Thermal Vacuum Test, a cleanroom was built that attached directly to the 60-year-old Chamber A. The cleanroom and chamber were outfitted with independent environmental control systems each providing ISO Class 71 air cleanliness. To maintain balanced, positive pressure in both the cleanroom and chamber volumes, a special control protocol was developed and successfully implemented. Dual back-up environmental control units (one each for the chamber and cleanroom) were installed just outside the building to provide environmental control redundancy due to a single source chilled water supply and weather threats. In addition, lack of a dedicated cleanroom airlock facilitating clean ingress and egress made it necessary to perform additional cleaning and packaging, as well as augment the uncontrolled truck lock space with small clean tents for pre-cleaning. Special procedures were developed to allow ingress of extra-large support equipment required for load testing of the cleanroom crane, installation of optical equipment in Chamber A and accommodation of the OTIS shipping container. A thorough bake-out and cleaning of Chamber A was also necessary to reduce volatiles from the shroud’s black thermal paint and to reduce particle fallout. Acrylic adhesive fracture discovered during early cryo-testing represented a significant challenge that was successfully mitigated prior to OTIS testing. A dedicated team of Contamination Control (CC) Technicians was specifically trained to clean support equipment and screen materials entering the cleanroom and chamber to ensure cleanliness and vacuum compatibility.

James Webb Space Telescope↗
NASA NTRSDate not supplied

Dual and Multi-Spectral Band SLS Infrared Camera Systems

Based on the recent success of our strained-layer superlattice (SLS)-based infrared (IR) camera that performed Earth imaging from the International Space Station (ISS) in 2019 we have built, what we consider, to be the next generation multi-band SLS imaging system. The Compact Thermal Imager (CTI) was installed on the Robotic Refueling Mission 3 (RRM3) and attached to the exterior of the ISS. From this location we were able to capture 15 million images of a multitude of fires around the globe in 2019. This unexpected trove of data initiated quite a bit of scientific interest to further utilize this imaging capability but would include features to more precisely monitor terrestrial fires and other surface phenomena. To this end, we developed a technique to install specific bandpass filters directly onto the SLS detector hybrid assembly. Utilizing this technique we have built a CTI-2 camera system with two filters, 4 and 11µm, and have made a second detector assembly with six filter bands from 4-12µm. This second system will also be used to supplement Landsat remote imaging monitoring approximate land surface temperatures, monitor evapotranspiration, sea ice and glacier dynamics. The CTI-2 camera is based on a 1,024x1,024 (1kx1k) format SLS detector hybridized to a FLIR ISC0404 readout integrated circuit (ROIC). The six band SLS focal plane array is based on the 640x512 FLIR ISC 9803 ROIC. This camera system is based on the Landsat 8 and 9 Thermal IR Sensors (TIRS) instrument and one of its purposes is to perform ground truthing for the Landsat 8/9 data at higher spectral resolution. Both Landsat TIRS instruments are dual band thermal IR sensors centered on 11 and 12µm (each with about a 1µm bandpass). Both of our SLS systems utilize a Ricor K548 cryocooler. To streamline costs and development time we used commercial optics and both commercial and custom NASA electronic components. A primary feature of these camera systems is the incorporation of specific filters to collect fire data at ~3.9µm and thermal data at ~11µm. The CTI-2 instrument is designed for 37 m /pixel spatial resolution from 410km orbit (ISS orbit). In this paper, we will present the design and performance of the focal plane, optics, electronics and mechanical structure of the dual‑band CTI-2 and the focal plane performance of the six‑band focal plane.

Murzy Jhabvala↗
NASA NTRSDate not supplied

OSIRIS-REx Earth Return & Entry: Navigation Operations & Lessons Learned

The Origins, Spectral Interpretation, Resource Identification, and Security–Regolith Explorer (OSIRIS-REx) spacecraft successfully returned to Earth on September24, 2024, safely delivering its Sample Return Capsule (SRC) to the Utah Test and Training Range (UTTR). This paper describes the navigation operations that occurred between the departure from Bennu and the return of the SRC. An overview is given of the Flight Dynamics System (FDS) that includes tracking, orbit determination (OD), maneuver planning, and interfaces with entry, descent, and landing. Operational details on the SRC release criteria and conjunction assessment considerations are also provided. Lessons learned are presented that may help future sample return or interplanetary entry missions.

Kenneth M. Getzandanner↗