Meteorological support for remote sensing programs

Many earth-oriented remote sensing spacecraft and aircraft programs are affected by the presence of clouds. Like aerial photography, they require clear or mostly clear skies. To cope with the cloud problem, the National Weather Service through its Spaceflight Meteorology Group (SMG) of the Space Operations Support Division makes cloud cover forecasts, as part of its specialized weather service for various NASA remote sensing and other programs. Forecasting requirements vary in time from a few hours out to several days and in aerial extent from a particular locality to nearly global in coverage. Depending on the stage of program development, some remote sensing programs may involve special climatological studies for planning purposes or need ground-truth data for comparison with remotely sensed information. The importance of computer and weather satellite products to the SMG meteorologist is discussed and the nature of SMG's weather support of past, present, and future remote sensing programs is described

A study of stratospheric gases catalytically reacting on alumina

A vacuum system developed to study stratospheric gases reacting on Al2O3. Special attention was given to the reactions of HCl, SO2, and O3. Efforts were made to detect atoms and/or molecules produced by catalytic action of Al2O3 with mass spectrometer

Dense molecular clouds in the SN2008fp host galaxy

(abridged) We use observations of interstellar absorption features, such as atomic and molecular lines as well as diffuse interstellar bands (DIBs), towards SN2008fp to study the physical properties of extra-galactic diffuse interstellar clouds in the host galaxy, ESO428-G14. The properties of the intervening dust are investigated via spectropolarimetry. The spectra of SN2008fp reveal a complex of diffuse atomic clouds at radial velocities in line with the systematic velocities of the host galaxy (~1700 km/s). A translucent (A_V ~ 1.5 mag) cloud is detected at a heliocentric velocity of 1770 km/s This cold dense cloud is rich in dense atomic gas tracers, molecules, as well as diffuse interstellar bands. We have detected both C2 and C3 for the first time in a galaxy beyond the Local Group. The CN (0,0) band line ratios are used to derive an in-situ measurement of the cosmic background radiation temperature in an external galaxy; this gives an excitation temperature of T = 2.9 +- 0.3 K. The interstellar polarization law deviates significantly from what is observed in the Galaxy, indicating substantial differences in the composition or size distribution of dust grains in the SN2008fp host galaxy. C2 is used to probe the cold diffuse ISM density and temperature. The lack of variability in the extra-galactic absorption line profiles over a period of one month implies that the absorbing material is not circumstellar and thus not affected directly by the SN event. Also it shows that there are no significant density variation in the small-scale structure of the molecular cloud down to 100 AU.Comment: 10 pages. Accepted for publication in A&A. Revisions include several small correction

Eyes in the sky: Interactions between AGB winds and the interstellar magnetic field

We aim to examine the role of the interstellar magnetic field in shaping the extended morphologies of slow dusty winds of Asymptotic Giant-branch (AGB) stars in an effort to pin-point the origin of so-called eye shaped CSE of three carbon-rich AGB stars. In addition, we seek to understand if this pre-planetary nebula (PN) shaping can be responsible for asymmetries observed in PNe. Hydrodynamical simulations are used to study the effect of typical interstellar magnetic fields on the free-expanding spherical stellar winds as they sweep up the local interstellar medium (ISM). The simulations show that typical Galactic interstellar magnetic fields of 5 to 10 muG, are sufficient to alter the spherical expanding shells of AGB stars to appear as the characteristic eye shape revealed by far-infrared observations. The typical sizes of the simulated eyes are in accordance with the observed physical sizes. However, the eye shapes are of transient nature. Depending on the stellar and interstellar conditions they develop after 20,000 to 200,000yrs and last for about 50,000 to 500,000 yrs, assuming that the star is at rest relative to the local interstellar medium. Once formed the eye shape will develop lateral outflows parallel to the magnetic field. The "explosion" of a PN in the center of the eye-shaped dust shell gives rise to an asymmetrical nebula with prominent inward pointing Rayleigh-Taylor instabilities. Interstellar magnetic fields can clearly affect the shaping of wind-ISM interaction shells. The occurrence of the eyes is most strongly influenced by stellar space motion and ISM density. Observability of this transient phase is favoured for lines-of-sight perpendicular to the interstellar magnetic field direction. The simulations indicate that shaping of the pre-PN envelope can strongly affect the shape and size of PNe.Comment: Accepted for publication in A&A. Final version will contain animated result

Flexible radiator system: Executive summary

A full scale prototype flexible radiator panel was designed, built and tested. The panel, has approximately 173 sq ft of radiating area and is designed to reject 1.33 kW of heat to a 0 F sink with a 100 F fluid inlet. The panel is constructed from a flexible Teflon/silver mesh fin surrounding 1/8 inch Teflon tubes. The prototype panel is stowed on a 10 inch diameter by 4 foot wide drum. (It rolls up to a diameter of 17 inches when fully stowed). Deployment of the soft tube prototype is via two four inch diameter Kevlar/Mylar inflation tubes with flat springs incorporated in each tube. Nitrogen is normally used for the deployment with approximately 1 psi required. The springs retract the panels when the inflation tubes are deflated. Another method of deployment available for the soft tube flexible is a motor driven deployable boom. This eliminates the need for expendables when the panel area is varied during the mission for heat load control. The soft tube panel is designed for a 90% probability of no punctured tube in a 30 day mission. The acceptable working fluids for this soft tube flexible are Coolanol 15, Coolanol 20 and Glycol/water (a eutectic mixture)

Fabrication and analogue applications of nanoSQUIDs using Dayem bridge junctions

We report here recent work at the U.K. National Physical Laboratory on developing nanoscale SQUIDs using Dayem bridge Josephson junctions. The advantages are simplicity of fabrication, exceptional low-noise performance, toward the quantum limit, and a range of novel applications. Focused ion beam patterned Nb SQUID, possessing exceptionally low noise (∼200 nΦ0/Hz1/2 above 1 kHz), and operating above 4.2 K can be applied to measurement of nanoscale magnetic objects or coupled to nanoelectromechanical resonators, as well as single particle detection of photons, protons, and ions. The limited operating temperature range may be extended by exposing the Dayem bridges to carefully controlled ion beam implantation, leading to nonreversible changes in junction transition temperature.The work reported here was supported in part by the EMRP projects ‘MetNEMS’ NEW-08 and ‘BioQUART’SIB-06. The EMRP is jointly funded by the EMRP participating countries within EURAMET and the European Union

Is BFKL ruled out by the Tevatron gaps between jets data ?

We have performed a detailed phenomenological investigation of the hard colour singlet exchange process observed at the Tevatron in events that have a large rapidity gap between outgoing jets. We include the effects of multiple interactions to obtain a prediction for the gap survival factor. Comparing the data on the fraction of gap events with the prediction from BFKL pomeron exchange we find agreement provided that a constant value of alpha_s is used in the BFKL calculation. Moreover, the value of alpha_s is in line with that extracted from measurements made at HERA.Comment: 5 pages, 5 figures. Talk given at the Tevatron Run 2 QCD and Weak Boson Physics workshop, Nov 4-6 199

Studying the small scale ISM structure with supernovae

AIMS. In this work we explore the possibility of using the fast expansion of a Type Ia supernova photosphere to detect extra-galactic ISM column density variations on spatial scales of ~100 AU on time scales of a few months. METHODS. We constructed a simple model which describes the expansion of the photodisk and the effects of a patchy interstellar cloud on the observed equivalent width of Na I D lines. Using this model we derived the behavior of the equivalent width as a function of time, spatial scale and amplitude of the column density fluctuations. RESULTS. The calculations show that isolated, small (<100 AU) clouds with Na I column densities exceeding a few 10^11 cm^-2 would be easily detected. In contrast, the effects of a more realistic, patchy ISM become measurable in a fraction of cases, and for peak-to-peak variations larger than ~10^12 cm^-2 on a scale of 1000 AU. CONCLUSIONS. The proposed technique provides a unique way to probe the extra-galactic small scale structure, which is out of reach for any of the methods used so far. The same tool can also be applied to study the sub-AU Galactic ISM structure.Comment: 6 pages, 3 figures. Accepted for publication in Astronomy & Astrophysic