23,253 research outputs found
Docking and retrieval mechanism
An engineering prototype docking and retrieval mechanism (DRM) which enables two spacecraft to dock and be structurally joined on-orbit is described. The joining of two spacecraft or payloads on-orbit supports future planned space activities such as payload servicing, deployment and retrieval, and assembly or large space systems. Advantages of the DRM include: it is a nonimpact docking mechanism; does not require impact absorbing mechanisms or attitude stabilization on the target spacecraft; is capable of docking to a spinning spacecraft; and can spin up and deploy a spinning spacecraft or payload
Reduction and analysis of data from OGO-4 experiment 15 Final report, 1 Nov. 1969 - 30 Nov. 1970
Procedures for processing atmospheric composition data obtained through use of sweeping quadrupole mass spectrometer on OGO-4 satellit
Loki, Io: New groundbased observations and a model describing the change from periodic overturn
Loki Patera is the most powerful volcano in the solar system. We have
obtained measurements of Loki's 3.5 micron brightness from NASA's Infrared
Telescope Facility (IRTF) and have witnessed a change from the periodic
behavior previously noted. While Loki brightened by a factor of several every
540 days prior to 2001, from 2001 through 2004 Loki remained at a constant,
medium brightness. We have constructed a quantitative model of Loki as a
basaltic lava lake whose solidified crust overturns when it becomes buoyantly
unstable. By altering the speed at which the overturn propagates across the
patera, we can match our groundbased brightness data. In addition, we can match
other data taken at other times and wavelengths. By slowing the propagation
speed dramatically, we can match the observations from 2001-2004. This slowing
may be due to a small change in volatile content in the magma
Aspects of Coulomb Dissociation and Interference in Peripheral Nucleus-Nucleus Collisions
Coherent vector meson production in peripheral nucleus-nucleus collisions is
discussed. These interactions may occur for impact parameters much larger than
the sum of the nuclear radii. Since the vector meson production is always
localized to one of the nuclei, the system acts as a two-source interferometer
in the transverse plane. By tagging the outgoing nuclei for Coulomb
dissociation it is possible to obtain a measure of the impact parameter and
thus the source separation in the interferometer. This is of particular
interest since the life-time of the vector mesons are generally much shorter
than the impact parameters of the collisions.Comment: 10 pages, 4 figures, Presented at the Workshop on Electromagnetic
Probes of Fundamental Physics, Erice, Italy, 16-21 October, 200
Magmatic intrusions control Io's crustal thickness
Io, the most volcanically active body in the solar system, loses heat through
eruptions of hot lava. Heat is supplied by tidal heating and is thought to be
transferred through the mantle by magmatic segregation, a mode of transport
that sets it apart from convecting terrestrial planets. We present a model that
couples magmatic transport of tidal heat to the volcanic system in the crust,
in order to determine the controls on crustal thickness, magmatic intrusions,
and eruption rates. We demonstrate that magmatic intrusions are a key component
of Io's crustal heat balance; around 80% of the magma delivered to the base of
the crust must be emplaced and frozen as plutons to match rough estimates of
crustal thickness. As magma ascends from a partially molten mantle into the
crust, a decompacting boundary layer forms, which can explain inferred
observations of a high-melt-fraction region.Comment: Accepted to JGR:Planets. 24 pages inc appendices and references. 7
figure
Photon induced secondary electron emission
Numerical models for predicting photon-induced secondary electron emission are presented. The results are compared with experimental measurements made using a Co-60 gamma ray source
Data Compression System with a Minimum Time Delay Unit-Patent
Minimum time delay unit for conventional time multiplexed data compression channel
Evaluation of the ADVIA (R) Centaur (TM) TSH-3 assay
An analytical evaluation of the thyroid stimulating hormone (TSH-3) assay on the Sayer ADVIA(R) Centaur(TM) immunoassay system was performed. General analytical requirements (linearity, resistance to typical interferences, absence of a carry-over effect) were fulfilled and reproducibility was satisfactory. Inter-assay coefficient of variation (CV) of a human serum pool with a concentration of 0.014 mU/l was 22.3%; at concentrations between 0.26 and 83 mU/l CV was below 6%. Method comparison study demonstrated close agreement of TSH results compared to those obtained with the Roche Elecsys(R) 2010 TSH assay (ADVIA Centaur = 1.08 x Elecsys - 0.18 mU/l; r = 0.987; n = 324). Handling and practicability of the ADVIA Centaur system proved to be convenient with a very high sample throughput. We conclude that the ADVIA Centaur TSH-3 assay meets requirements for clinical use
Two-Photon Interactions with Nuclear Breakup in Relativistic Heavy Ion Collisions
Highly charged relativistic heavy ions have high cross-sections for
two-photon interactions. The photon flux is high enough that two-photon
interactions may be accompanied by additional photonuclear interactions. Except
for the shared impact parameter, these interactions are independent. Additional
interactions like mutual Coulomb excitation are of experimental interest, since
the neutrons from the nuclear dissociation provide a simple, relatively
unbiased trigger.
We calculate the cross sections, rapidity, mass and transverse momentum
( distributions for exclusive production of mesons and
lepton pairs, and for reactions accompanied by mutual Coulomb
dissociation. The cross-sections for interactions accompanied by
multiple neutron emission () and single neutron emission () are
about 1/10 and 1/100 of that for the unaccompanied interactions.
We discuss the accuracy with which these cross-sections may be calculated. The
typical of final states is several times smaller than for
comparable coherent photonuclear interactions, so may be an effective
tool for separating the two classes of interactions.Comment: 17 pages, 12 figure
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