An Automated 2-D Line-Shift Measurement From Smoothed and Leveled Diagnostic Interferometric Images of Exploded-Wire Plasma

A novel, automated, 2-D line-shift measurement algorithm is presented for optical interferometry in plasma diagnostics. By using the smoothing and leveling (SL) algorithm as a preprocessing stage to the Fourier transform method (FTM), the proposed SL-FTM algorithm extracts the line shift without a priori knowledge of the spectral properties of the image, a common requirement of other FTM-based algorithms. The algorithm is simple to implement, and demonstrated for side-on views of plasma from exploded wires, where the interference patterns suffer from low contrast, low signal-to-noise ratio (SNR), and spatially varying intensity. SL-FTM and FTM are compared via Monte Carlo simulation of noisy images with realistic background variation. They are shown to have the accuracies of 0.019 and 0.016 lines, respectively. In addition, the cause of the accuracy difference is studied using a modified Jaccard similarity measure. The measure shows how SL-FTM provides a smoother phase surface than FTM, but underestimates the maximum line shift by up to 15%. Also, the well-known contour tracing method (CTM) is automated as SL-CTM. The automated forms of FTM and CTM (i.e., SL-FTM and SL-CTM) permit, for the first time, their direct comparison for a wide range of noisy images. SL-CTM, and by extension, CTM, achieves the best accuracy of 0.013 lines. Finally, each method is shown to have accuracy that exceeds the standard diagnostic accuracy requirement of 0.05 lines

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies

Isotope ratios of H, C, and O in CO2 and H2O of the Martian atmosphere

Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and O-18/O-16 in water and C-13/C-12, O-18/O-16, O-17/O-16, and (CO)-C-13-O-18/(CO)-C-12-O-16 in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established similar to 4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing