Search

The mid-latitude upper atmosphere (UA) region lies inside the plasmaspheric boundary and witnesses several space weather phenomena as a direct consequence of magnetosphere-ionosphere coupling. One such phenomena is the storm enhanced density (SED), which occurs during geomagnetic storms over mid-latitudes and have been studied primarily using radar and satellite observations. Important to this study is the investigation of UA using high spectral resolution ground-based measurements of thermospheric OI 630.0 nm dayglow emissions obtained from Boston, a mid-latitude location. These optical emissions are produced by photo-dissociation, photoelectron impact and dissociative reaction mechanisms and are very sensitive to any changes in the UA dynamics. An anomalous enhancement (>1 kR) was observed in these dayglow emission intensities near evening hours of local time on 9 Nov 2004, during a geomagnetic storm between 7-9 Nov 2004 (Apex Kp=9-). The observed dayglow enhancement is interpreted as a SED event and further confirmed using complimentary measurements from the Millstone Hill incoherent scatter radar (ISR), GPS total electron content, and SuperDARN datasets in the context of a large-scale space weather effect. Additionally, a photochemical model-GLOW estimated dayglow emissions, in which ISR measured electron/ion temperatures and electron densities were provided as inputs also match well with our observed emissions. This study presents the results on various associated ionospheric characteristics indicating the presence of SED over Boston and its effect in daytime airglow emissions possibly observed for the first time., The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

The development of multifunctional nanocomposite materials is of great interest for various biomedical applications. A popular approach to produce tailored nanocomposites is to incorporate functional nanoparticles into hydrogels. Here, a benign atmospheric pressure microplasma synthesis approach has been deployed for the synthesis of metal and alloy NPs in‐situ in a poly (vinyl alcohol) hydrogel. The formation of gold, silver, and gold‐silver alloy NPs was confirmed via spectroscopic and microscopic characterization techniques. The properties of the hydrogel were not compromised during formation of the composites. Practical applications of the NP/PVA nanocomposites has been demonstrated by anti‐bacterial testing. This establishes AMP processing as a viable one‐step technique for the fabrication of NP/hydrogel composites, with potential multifunctionality for a range of biomedical applications.

Project Blue is designed to deliver a small coronagraphic space telescope mission to low-Earth orbit capable of detecting an Earth-like planet in the habitable zones of the Sun-like stars Alpha Centauri A and B within the next 4 years within a Mission of Opportunity budget envelope. The concept heavily leverages emerging commercial capabilities -- including the telescope optics, spacecraft bus and launch vehicle -- and emphasizes a public-private partnership approach., 5 pages; White paper submitted to the Exoplanet Science Strategy study of the National Academies of Sciences, Engineering and Medicine

We test the utility of the OII 83.4 nm emission feature as a measure of ionospheric parameters. Observed with the Remote Atmospheric and Ionospheric Detection System (RAIDS) Extreme Ultraviolet Spectrograph on the International Space Station (ISS), limb profiles of 83.4 nm emissions are compared to predicted dayglow emission profiles from a theoretical model incorporating ground-based electron density profiles measured by the Millstone Hill radar and parameterized by a best-fit Chapman-{\alpha} function. Observations and models are compared for periods of conjunction between Millstone Hill and the RAIDS fields-of-view. These RAIDS observations show distinct differences in topside morphology between two days, 15 January and 10 March 2010, closely matching the forward model morphology and demonstrating that 83.4 nm emission is sensitive to changes in the ionospheric density profile from the 340 km altitude of the ISS during solar minimum. We find no significant difference between 83.4 nm emission profiles modeled assuming a constant scale height Chapman-{\alpha} best-fit to the ISR measurements and those assuming varying scale height.

A NASA sounding rocket for high contrast imaging with a visible nulling coronagraph, the Planet Imaging Coronagraphic Technology Using a Reconfigurable Experimental Base (PICTURE-B) payload has made two suborbital attempts to observe the warm dust disk inferred around Epsilon Eridani. We present results from the November 2015 launch demonstrating active wavefront sensing in space with a piezoelectric mirror stage and a micromachine deformable mirror along with precision pointing and lightweight optics in space., Presented at SPIE Astronomical Telescopes + Instrumentation

The PICTURE-C mission will fly a 60 cm off-axis unobscured telescope and two high-contrast coronagraphs in successive high-altitude balloon flights with the goal of directly imaging and spectrally characterizing visible scattered light from exozodiacal dust in the interior 1-10 AU of nearby exoplanetary systems. The first flight in 2017 will use a 10^(-4) visible nulling coronagraph (previously flown on the PICTURE sounding rocket) and the second flight in 2019 will use a 10^(-7) vector vortex coronagraph. A low-order wavefront corrector (LOWC) will be used in both flights to remove time-varying aberrations from the coronagraph wavefront. The LOWC actuator is a 76-channel high-stroke deformable mirror packaged on top of a tip-tilt stage. This paper will detail the selection of a complementary high-speed, low-order wavefront sensor (LOWFS) for the mission. The relative performance and feasibility of several LOWFS designs will be compared including the Shack-Hartmann, Lyot LOWFS, and the curvature sensor. To test the different sensors, a model of the time-varying wavefront is constructed using measured pointing data and inertial dynamics models to simulate optical alignment perturbations and surface deformation in the balloon environment.

Explorers have made breakthroughs in many fields of astrophysics. The science from both these missions contributed to three Nobel Prizes - Giacconi (2002), Mather, and Smoot (2006). Explorers have: marked the definitive beginning of precision cosmology, discovered that short gamma-ray bursts are caused by compact star mergers and have measured metalicity to redshifts z>6. NASA Explorers do cutting-edge science that cannot be done by facility-class instruments. The Explorer program provides a rapid response to changing science and technology, to enable cutting-edge science at moderate cost. Explorers also enable innovation, and engage & train scientists, managers and engineers, adding human capital to NASA and the nation. The astrophysics Explorer launch rate now being achieved is 1 per 3 years, and budget projections are in the $150M/year range for the next five years. A newly Vigorous Explorer Program should be created to: 1. Reach the long-stated goal of annual astrophysics launches; 2. Find additional launch options for Explorers and actively encourage cost savings in launchers and spacecraft, such as new commercial vehicles and innovative partnerships. 3. Mitigate risk via stronger technical development and sub-orbital programs, and through longer, more thorough, Phase A programs, potentially reducing the need for a 30% contingency; 4. Strive to protect the funding for missions that have reached Phase B, to prevent significant launch slips and cancellations, with a goal of 4 to 5 years from Phase B to launch; 5. Review the project management procedures and requirements to seek cost reductions, including the risk management strategy and the review and reporting process; 6. Review and possibly modify the cost caps for all Explorer classes to optimize scientific returns per dollar. [ABRIDGED], 18 pages, no figures. An Activities/Program White Paper submitted to the Astro2010 NAS/NRC Decadal Review of Astronomy and Astrophysics

International audience

In a collaborative effort, NASA Ames Research Center, the University of California Berkeley, and Boston University have developed ground software for a small satellite. This paper describes the ground communication software, the data archiving and serving system, and the data display and satellite scheduling in sufficient detail to allow prospective small satellite operators to explore its possible use or extension.