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Optical windows play a crucial role in laser ablation systems by protecting delicate components inside the chamber while allowing the transmission of laser energy. However, material buildup during the laser ablation process can lead to a significant loss of optical transmission over time. In this work, material deposition on the optical window by laser ablation of olivine using two laser systems operating at 30 kHz, 1 mJ pulse energy, and 20 Hz, 9.6 mJ pulse energy was performed and its impact on the window's transmission properties, laser-induced breakdown spectroscopy (LIBS) signal, and window recovery is presented. Ablation at 30 kHz with 1 mJ pulses for 10 min resulted in substantial particle deposition on the window, causing a significant drop in transmission. Transmission of clean window dropped abruptly from 90% to nearly 0% (in the UV region from 200 to 300 nm) and 35% (at 600 nm) affecting the LIBS signal. In contrast, ablation at 20 Hz with 9.6 mJ pulses for 5 min showed no material deposition or transmission loss. Additionally, the study demonstrated that the same laser system used for ablation could be employed to remove the deposited material from the window, facilitating its recovery. Laser cleaning of the window at 30 kHz and 12 W average power restored the transmission values from 39% to 62% at 400 nm in the UV region, with potential for further improvement through parameter optimization. In addition, the identification of the hydroxyl group in olivine, which is relevant to NASA's terahertz heterodyne spectrometer for in situ resource utilization project for the validation of water molecules is presented. [ABSTRACT FROM AUTHOR]

We obtained high-resolution spectra of Jupiter between 4.6 and 5.4 µm using NIRSPEC on the Keck 2 telescope in February 2017. We measured the spatial variation of NH 3 , H 2 O, and the pressure level of deep (p > 3 bar) clouds using two geometries. We aligned the slit north–south on Jupiter's Central Meridian to measure the spatial variation of the gas composition and cloud structure between 66 ° N and 70 ° S. With the slit aligned east–west, we also examined the longitudinal variation at two regions of the North Equatorial Belt (NEB) at 18 ° N and at 8 ° N near the latitude of the Galileo Probe entry site. We used the integrated line absorption, also known as the equivalent width, of deuterated methane (CH 3 D) at 4.66 µm to derive the pressure level of deep clouds between 3 and 7 bar. From thermochemical models, these are most likely water clouds. At the location of a deep cloud revealed by HST methane-band imaging, we found spectroscopic evidence for an opaque cloud at the 5 bar level. We also identified regions on Jupiter that lacked deep clouds but exhibited evidence for upper clouds and enhanced NH 3 . We estimated column-averaged mole fractions of H 2 O and NH 3 above the opaque lower boundary of the deep cloud. The meridional scan exhibited significant belt-zone structure with retrieved NH 3 abundances in the 200–400 ppm range above the opaque lower cloud, except for a depletion (down to 90 ppm) in the NEB. Water in Jupiter's belts varies from a maximum of 7 ppm at 8 ° S to a minimum of 1.5 ppm at 23 ° S. We found evidence for water clouds and enhanced NH 3 and H 2 O in the South Equatorial Belt Outbreak region at 13 ° S. The NEB is a heterogeneous region with significant variation in all of these quantities. The NH 3 abundance at 18 ° N and 8 ° N varies with the longitude with mole fractions between 120 and 300 ppm. The H 2 O abundance at these same latitudes varies with the longitude with mole fractions between 3 and 10 ppm. Our volatile mole fractions apply to the 5 to 8 bar pressure range (or to the level of an opaque cloud top where found at shallower pressure); therefore, they imply a deeper gradient continuing to increase toward higher concentrations detected by the Galileo Probe Mass Spectrometer at 11 and 20 bar. Hot Spots in the NEB exhibit minimal cloud opacity; however, they lack prominent anomalies in the concentrations of NH 3 or H 2 O. [ABSTRACT FROM AUTHOR]

Multispectral snapshot imagers are capable of producing 2-D spatial images with a single exposure at selected, numerous wavelengths using the same camera, therefore, operate differently from push broom or whiskbroom imagers. They are payloads of choice in multi-angular, multi-spectral imaging missions that use small satellites flying in controlled formation, to retrieve Earth science measurements dependent on the target’s bidirectional reflectance-distribution function. Narrow fields of view are needed to capture images with moderate spatial resolution. This paper quantifies the dependencies of the imager’s optical system, spectral elements, and camera on the requirements of the formation mission and their impact on performance metrics, such as spectral range, swath, and signal-to-noise ratio (SNR). All variables and metrics have been generated from a comprehensive, payload design tool. The baseline optical parameters selected (a diameter of 7 cm, a focal length of 10.5 cm, a pixel size of 20~\mu \textm , and a field of view of 1.15°) and snapshot imaging technologies are available. The spectral components shortlisted were waveguide spectrometers, acousto-optic tunable filters (AOTF), electronically actuated Fabry–Perot interferometers, and integral field spectrographs. Qualitative evaluation favored AOTFs, because of their low weight, small size, and flight heritage. Quantitative analysis showed that the waveguide spectrometers perform better in terms of achievable swath (10–90 km) and SNR (>20) for 86 wavebands, but the data volume generated will need very high bandwidth communication to downlink. AOTFs meet the external data volume caps well as the minimum spectral (wavebands) and radiometric (SNR) requirements, therefore, are found to be currently feasible and design changes to improve swath suggested. [ABSTRACT FROM PUBLISHER]

EPOXI (EPOCh + DIXI) is a NASA Discovery Program Mission of Opportunity using the Deep Impact flyby spacecraft. The EPOCh (Extrasolar Planet Observation and Characterization) Science Investigation will gather photometric time series of known transiting exoplanet systems from January through August 2008. Here we describe the steps in the photometric extraction of the time series and present preliminary results of the first four EPOCh targets. [ABSTRACT FROM PUBLISHER]

The NASA Discovery mission EPOXI, utilizing the Deep Impact flyby spacecraft, comprises two phases: EPOCh (Extrasolar Planet Observation and Characterization) and DIXI (Deep Impact eXtended Investigation). With EPOCh, we use the 30-cm high resolution visible imager to obtain ultraprecise photometric light curves of known transiting planet systems. We will analyze these data for evidence of additional planets, via transit timing variations or transits; for planetary moons or rings; for detection of secondary eclipses and the constraint of geometric planetary albedos; and for refinement of the system parameters. Over a period of four months, EPOCh observed four known transiting planet systems, with each system observed continuously for several weeks. Here we present an overview of EPOCh, including the spacecraft and science goals, and preliminary photometry results. [ABSTRACT FROM PUBLISHER]

The demonstration of a newly developed compact thermal imager (CTI) on the International Space Station (ISS) has provided not only a technology advancement but a rich high-resolution dataset on global clouds, atmospheric and land emissions. This study showed that the free-running CTI instrument could be calibrated to produce scientifically useful radiance imagery of the atmosphere, clouds, and surfaces with a vertical resolution of ~460 m at limb and a horizontal resolution of ~80 m at nadir. The new detector demonstrated an excellent sensitivity to detect the weak limb radiance perturbations modulated by small-scale atmospheric gravity waves. The CTI's high-resolution imaging was used to infer vertical cloud temperature profiles from a side-viewing geometry. For nadir imaging, the combined high-resolution and high-sensitivity capabilities allowed the CTI to better separate cloud and surface emissions, including those in the planetary boundary layer (PBL) that had small contrast against the background surface. Finally, based on the ISS's orbit, the stable detector performance and robust calibration algorithm produced valuable diurnal observations of cloud and surface emissions with respect to solar local time during May–October 2019, when the CTI had nearly continuous operation. [ABSTRACT FROM AUTHOR]