Search

Lunar Ice Cube, scheduled to be launched on ARTEMIS I in late 2021, is a deep space cubesat mission with the goals of demonstrating 1) a cubesat-scale instrument (BIRCHES) capable of addressing NASA HEOMD Strategic Knowledge Gaps related to lunar volatile distribution (abundance, location, and transportation physics of water ice), and 2) cubesat propulsion, via the Busek BIT 3 RF Ion engine. The mission will also demonstrate the AIM/IRIS microcryocooler for the first time in deep space. BIRCHES integration is nearly complete, with several changes made to the thermal design to improve detector performance. Final preflight instrument testing and calibration, our ongoing concern to be emphasized here, have been delayed due to the mandated closure rules of NASA facilities. Lunar Ice Cube, along with two other cubesats deployed from ARTEMIS I, Lunar Flashlight and LunaH-Map, will be the first deep cubesat missions to deliver science data to the Planetary Data System.

During 2019, an infrared camera, the compact thermal imager (CTI), recorded 15 million images of the Earth from the International Space Station. CTI is based on strained-layer superlattice (SLS) detector technology. The camera covered the spectral range from 3 to 11 µm in two spectral channels, 3.3–5.4 and 7.8–10.7 µm. Individual image frames were 26 × 21 k m 2 projected on the ground, with 82 m pixel resolution. A frame time of 2.54 s created continuous image swaths with a 13% along-track image overlap. Upper limits determined on the ground and in flight for the electronic offset, read noise, and dark current demonstrated the stability of the SLS detector and camera over many months. Temperature calibration was established using a combination of preflight and in-flight measurements. A narrowband approximation of temperature as a function of photon counts produced an analytic relationship covering a temperature range of 0°–400°C. Examples of CTI images illustrate temperature retrievals over sea ice, urban and agricultural areas, desert, and wildfires.

Recent polarimetric observations of the 12.32-μm emission line have provided the observational basis for deriving vector magnetic fields in the upper photosphere with great sensitivity. We use a line source function from the non-LTE model of Carlsson, Rutten and Shchukina, and calculate the radiative transfer of the Stokes I, Q, U, and V profiles. The results show that the profiles are not significantly affected by magneto-optical effects or by saturation, and reliable vector fields can be extracted by simply fitting the Seares relations to the Stokes profiles. Vector field observations for sunspots have shown that the field extends well beyond the photometric boundary of the sunspot, but that the field strength at the penumbral/photospheric boundary is less than half of the sunspot-center value. Within a mature sunspot, the 12-μm line profiles contain essentially no unpolarized radiation, indicating that the field is not intermittent in the sense of containing discrete flux tubes separated by field-free regions. We describe the design of a 12-μm Stokes polarimeter incorporating a high-resolution Fabry-Perot etalon and a 128 × 128 infrared array detector.

Measurements are reported on a grating-tuned CO/sub 2/ laser, containing an isotopic mixture of /sup 16/O/sup 12/C/sup 16/O, /sup 16/O/sup 12/C/sup 18/O, and /sup 18/O/sup 12/C/sup 18/O. The P/sub 6/ and R/sub 14/ lines of /sup 16/O/sup 12/C/sup 16/O were found to have anomalously high intensities. These anomalies are produced by the near coincidence of the transition frequencies in two distinct isotopes, permitting them to act as a single indistinguishable population. These two lines can be used to identify the rotational quantum numbers in the P and R branch spectra, thereby permitting absolute wavelength calibration to be achieved. >

We report on our molecular spectroscopy effort to determine frequencies, intensities, shapes and broadening in fundamental and low-lying hot band transitions for molecules of interest to contemporary planetary atmospheric investigations. The laboratory measurements, obtained with the NASA/GSFC Heterodyne Instrument for Planetary Wind and Composition (HIPWAC), are described in a companion paper in this session (see Blass et al.) which also compares our results to those of other researchers (e.g., Vander Auwera et al.). Herein we present the analysis methodology and interpretation of the laboratory measurements. We identified molecular species of significance to current outer-planet missions such as the Cassini Mission to Jupiter, Saturn and Titan: ethane (C2H6), including both normal and primary hot band (i.e., _9 and _9 + _4 _ _4); ethylene (C2H4); and allene (C3H4). The laboratory measurements which are the basis for the results reported herein were obtained at a spectral resolution of 0.00003 cm_1 (_1MHz) at 12 µm. At this spectral resolution, the rotation-vibration transitions measured under laboratory conditions (ambient temperature and _1 Torr pressure) are fully resolved and identified without ambiguity. The principal objective is to provide critical laboratory truth for the interpretation of infrared spectral observations of the Cassini mission, follow on missions to Titan and the outer planets, and in the re-interpretation of mid-IR emission spectra from Voyager IRIS, ISO, and ground based IR data of the outer planets. Resultant line intensities (

The absolute infrared intensities of transitions in the _9 band of ethane have long been a subject of controversy (Gunson 1996, Daunt 1984, Henry 1983, Auwera 2007, and references therein). Improving the ethane 12 µm database is one of the goals of this work. The spectra here acquired was obtained using the NASA Heterodyne Instrument for Planetary Wind And Composition (HIPWAC) in a laboratory setting. HIPWAC, in this environment, makes use of a blackbody source and a gas absorption cell. Observations were carried out from P(10) at 858.1583905 cm_1 to P(32) at 839.1958112 cm_1 of the 646 laser. The observational range is ± 3GHz centered on each laser line. HIPWAC has the ability to measure spectra by using infrared heterodyne techniques, in which an infrared source is combined with a laser local oscillator and focused on a photomixer, where the difference frequency between the source and laser is retrieved and analyzed. Using these techniques HIPWAC is able to achieve a very high resolution (_/__ > 106 ) and a high frequency specificity (> 10_8 ) in order to study low-pressure gases. The spectra was retrieved using an Acoustic-Optical Spectrometer (AOS) with a sampling interval of 1 MHz. The detector was a liquid Helium cooled HgCdTe Photomixer. The ethane was research grade (99.96 %) obtained from Matheson Gas Products. The gas was contained in a 30 cm straight-path cell with ZnSe windows. The gas pressure was 0.709 Torr, as measured by an MKS Baratron gauge, at a temperature of 26 degrees Celcius. Additional measurements were also done at 1.4 Torr and 2.8 Torr. The spectra acquired is double sided and was fitted using an IDL program. The quantum assignments were taken from previous atlases (Tennessee/GSFC and GEISA). Currently, similar measurements are also being done on Allene and OCS. In the future we would like to incorporate Quantum Cascade Lasers in our system to replace our CO2 gas lasers. Quantum Cascade lasers are very small solid-state devices with an output power of about 100 mW and limited tunability.

Recent polarimetric observations of the 12.32-μm emission line have provided the observational basis for deriving vector magnetic fields in the upper photosphere with great sensitivity. We use a line source function from the non-LTE model of Carlsson, Rutten and Shchukina, and calculate the radiative transfer of the Stokes I, Q, U, and V profiles. The results show that the profiles are not significantly affected by magneto-optical effects or by saturation, and reliable vector fields can be extracted by simply fitting the Seares relations to the Stokes profiles. Vector field observations for sunspots have shown that the field extends well beyond the photometric boundary of the sunspot, but that the field strength at the penumbral/photospheric boundary is less than half of the sunspot-center value. Within a mature sunspot, the 12-μm line profiles contain essentially no unpolarized radiation, indicating that the field is not intermittent in the sense of containing discrete flux tubes separated by field-free regions. We describe the design of a 12-μm Stokes polarimeter incorporating a high-resolution Fabry-Perot etalon and a 128 × 128 infrared array detector.

The Far-Infrared Absolute Spectrophotometer (FIRAS) instrument on the Cosmic Background Explorer (COBE) satellite was designed to accurately measure the spectrum of the cosmic microwave background radiation (CMBR) in the frequency range 1-95/cm with an angular resolution of 7 deg. We describe the calibration of this instrument, including the method of obtaining calibration data, reduction of data, the instrument model, fitting the model to the calibration data, and application of the resulting model solution to sky observations. The instrument model fits well for calibration data that resemble sky condition. The method of propagating detector noise through the calibration process to yield a covariance matrix of the calibrated sky data is described. The final uncertainties are variable both in frequency and position, but for a typical calibrated sky 2.6 deg square pixel and 0.7/cm spectral element the random detector noise limit is of order of a few times 10(exp -7) ergs/sq cm/s/sr cm for 2-20/cm, and the difference between the sky and the best-fit cosmic blackbody can be measured with a gain uncertainty of less than 3%.