Mitigate Microgravity Deconditioning Syndrome using Resistive Exercise as a Countermeasure

.We propose to design an optimized lower extremity force acquisition system (LEFAS) that integrates with a lower body negative pressure (LBNP) box and subject-specific protocols for improved fitness results by taking a computationally simulated optimization approach. Current countermeasures to date on the International Space Station lack sufficient mechanical and physiological loads to maintain preflight musculoskeletal (MSK) mass, strength, and aerobic capacity. Our approach combines LEFAS, LBNP and personalized controls to combat microgravity deconditioning syndrome including induced muscle atrophy, bone decalcification and poor cardiovascular health minimizing the gap between pre-flight and post-flight syndrome, allowing astronauts to respond to emergencies, and remain healthy during and after extended space travel. The LEFAS/LBNP countermeasure combines two forms of resistance achieving required loads and allowing for exploration at greater distances from Earth and extended stays in space. In parallel, we will educate students, teachers, and community about solving the challenges of human space travel using advanced modeling techniques and ground-based experiments

Orbital Evolution of Dust Size Particles Released From Catastrophic Asteroid Disruption

Infrared satellite detectors, such as IRAS (Infrared Astronomical Satellite) and WISE (Wide Field Infrared Survey Explorer), provide observational evidence of catastrophic asteroid disruptions in the form of zodiacal cloud dust bands. With observations of these bands, the asteroid parents and their families (fragments of disruptions) are studied to better understand the zodiacal cloud prior to disruption, as well as how asteroids contribute to the debris disk of the solar system\u27s zodiacal cloud. Before creating models that can be compared to satellite data, the dynamical evolutions of small particles resulting from different disruptions of different ages as they evolve into the inner solar system are tracked. The dynamical evolution code, written in IDL, simulates the orbital elements of small particles during disruption. It takes into consideration the gravitational and radiative forces affecting small particle orbits for specific families within their unique epochs of disruptions. Through plots of temporal variations of numerous orbital elements of the resulting disruptions, this team has begun comparing the dynamical evolution of small particles from different asteroidal disruptions, as they reach Near-Earth Space. Understanding the particles in this region is important for many reasons, including determining potential threats for spacecraft in future missions

SDTrimSP Simulations of Solar Wind Sputtering on Mercury: A Sensitivity Study to Establish a Best-Practice

Understanding the role solar wind (SW) ions play on surface sputtering of Mercury is critical to any exosphere model. The most common models use binary collision approximation (BCA) tools such as SDTrimSP. However, this state-of-the-art tool has many user-specific inputs and that are not immediately clear for more complex substrates such as minerals on celestial surfaces. These include surface binding energies, SW compositions, static vs. dynamic, and impact energy. Previous research has not kept these parameters consistent, making it unclear how sensitive sputtering behavior is to these parameters. As such, we have conducted a detailed sensitivity study into SDTrimSP parameters for simulating SW impacts. We have considered how several important simulation choices affect sputtering yields, composition, energy distribution, and damage. Results show that sputtering behavior is highly dependent on these parameters and can be used to establish a best practice methodology for SDTrimSP

Ram pressure feeding super-massive black holes

When supermassive black holes at the center of galaxies accrete matter (usually gas), they give rise to highly energetic phenomena named Active Galactic Nuclei (AGN). A number of physical processes have been proposed to account for the funneling of gas towards the galaxy centers to feed the AGN. There are also several physical processes that can strip gas from a galaxy, and one of them is ram pressure stripping in galaxy clusters due to the hot and dense gas filling the space between galaxies. We report the discovery of a strong connection between severe ram pressure stripping and the presence of AGN activity. Searching in galaxy clusters at low redshift, we have selected the most extreme examples of jellyfish galaxies, which are galaxies with long tentacles of material extending for dozens of kpc beyond the galaxy disk. Using the MUSE spectrograph on the ESO Very Large Telescope, we find that 6 out of the 7 galaxies of this sample host a central AGN, and two of them also have galactic-scale AGN ionization cones. The high incidence of AGN among the most striking jellyfishes may be due to ram pressure causing gas to flow towards the center and triggering the AGN activity, or to an enhancement of the stripping caused by AGN energy injection, or both. Our analysis of the galaxy position and velocity relative to the cluster strongly supports the first hypothesis, and puts forward ram pressure as another, yet unforeseen, possible mechanism for feeding the central supermassive black hole with gas.Comment: published in Nature, Vol.548, Number 7667, pag.30

First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data

Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a fully coherent search, based on matched filtering, which uses the position and rotational parameters obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto- noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have been developed, allowing a fully coherent search for gravitational waves from known pulsars over a fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of 11 pulsars using data from Advanced LIGO’s first observing run. Although we have found several initial outliers, further studies show no significant evidence for the presence of a gravitational wave signal. Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for the first time. For an additional 3 targets, the median upper limit across the search bands is below the spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried out so far

Science Opportunities offered by Mercury's Ice-Bearing Polar Deposits

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Increasing the Astrophysical Reach of the Advanced Virgo Detector via the Application of Squeezed Vacuum States of Light

Current interferometric gravitational-wave detectors are limited by quantum noise over a wide range of their measurement bandwidth. One method to overcome the quantum limit is the injection of squeezed vacuum states of light into the interferometer’s dark port. Here, we report on the successful application of this quantum technology to improve the shot noise limited sensitivity of the Advanced Virgo gravitational-wave detector. A sensitivity enhancement of up to 3.2±0.1  dB beyond the shot noise limit is achieved. This nonclassical improvement corresponds to a 5%–8% increase of the binary neutron star horizon. The squeezing injection was fully automated and over the first 5 months of the third joint LIGO-Virgo observation run O3 squeezing was applied for more than 99% of the science time. During this period several gravitational-wave candidates have been recorded