Micro-coupling active release mechanism

PatentA micro-coupling active release mechanism including a shape memory alloy (SMA) cylindrical ring that is fit into a bushing or other mating attachment creating an interference joint held in place by frictional forces. The interference joint can be released upon actuation in which the SMA cylindrical ring is heated causing it to shrink in size, relieving the frictional forces of the interference joint thereby releasing the SMA cylindrical ring fromt the bushing or other mating attachment

A Novel Approach for a Low-Cost Deployable Antenna

The Naval Research Laboratory (NRL) has designed, built, and fully qualified a low cost, low Passive Intermodulation (PIM) 12-foot (3.66-m) diameter deployable ultra high frequency (UHF) antenna for the Tacsat-4 program. The design utilized novel approaches in reflector material and capacitive coupling techniques. This paper discusses major design trades, unique design characteristics, and lessons learned from the development of the Tacsat 4 deployable antenna. This antenna development was sponsored by the Office of Naval Research

Learning and climate change

Learning – i.e. the acquisition of new information that leads to changes in our assessment of uncertainty – plays a prominent role in the international climate policy debate. For example, the view that we should postpone actions until we know more continues to be influential. The latest work on learning and climate change includes new theoretical models, better informed simulations of how learning affects the optimal timing of emissions reductions, analyses of how new information could affect the prospects for reaching and maintaining political agreements and for adapting to climate change, and explorations of how learning could lead us astray rather than closer to the truth. Despite the diversity of this new work, a clear consensus on a central point is that the prospect of learning does not support the postponement of emissions reductions today.Learning; Uncertainty; Climate change; Decision analysis

Optimized modeling of Gaia-Hipparcos astrometry for the detection of the smallest cold Jupiter and confirmation of seven low mass companions

© 2021 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This is the accepted manuscript version of an article which has been published in final form at https://doi.org/10.1093/mnras/stab2225To fully constrain the orbits of low mass circumstellar companions, we conduct combined analyses of the radial velocity data as well as the Gaia and Hipparcos astrometric data for eight nearby systems. Our study shows that companion-induced position and proper motion differences between Gaia and Hipparcos are significant enough to constrain orbits of low mass companions to a precision comparable with previous combined analyses of direct imaging and radial velocity data. We find that our method is robust to whether we use Gaia DR2 or Gaia EDR3, as well as whether we use all of the data, or just proper motion differences. In particular, we fully characterize the orbits of HD 190360 b and HD 16160 C for the first time. With a mass of 1.8$\pm$0.2$m_{\rm Jup}$ and an effective temperature of 123-176 K and orbiting around a Sun-like star, HD 190360 b is the smallest Jupiter-like planet with well-constrained mass and orbit, belonging to a small sample of fully characterized Jupiter analogs. It is separated from its primary star by 0.25$''$ and thus may be suitable for direct imaging by the CGI instrument of the Roman Space Telescope.Peer reviewe

Discovery of Planetary Systems With SIM

We are witnessing the birth of a new observational science: the discovery and characterization of extrasolar planetary systems. In the past five years, over 70 extrasolar planets have been discovered by precision Doppler surveys, most by members of this SIM team. We are using the data base of information gleaned from our Doppler survey to choose the best targets for a new SIN planet search. In the same way that our Doppler database now serves SIM, our team will return a reconnaissance database to focus Terrestrial Planet Finder (TPF) into a more productive, efficient mission

The Code of Protest. Images of Peace in the West German Peace Movements, 1945-1990

The article examines posters produced by the peace movements in the Federal Republic of Germany during the ColdWar, with an analytical focus on the transformation of the iconography of peace in modernity. Was it possible to develop an independent, positive depiction of peace in the context of protests for peace and disarmament? Despite its name, the pictorial selfrepresentation of the campaign ‘Fight against Nuclear Death’ in the late 1950s did not draw on the theme of pending nuclear mass death. The large-scale protest movement in the 1980s against NATO’s 1979 ‘double-track’ decision contrasted female peacefulness with masculine aggression in an emotionally charged pictorial symbolism. At the same time this symbolism marked a break with the pacifist iconographic tradition that had focused on the victims of war. Instead, the movement presented itself with images of demonstrating crowds, as an anticipation of its peaceful ends. Drawing on the concept of asymmetrical communicative ‘codes’ that has been developed in sociological systems theory, the article argues that the iconography of peace in peace movement posters could not develop a genuinely positive vision of peace, since the code of protest can articulate the designation value ‘peace’ only in conjunction with the rejection value ‘war’

Constraints on the architecture of the HD 95086 planetary system with the Gemini Planet Imager

We present astrometric monitoring of the young exoplanet HD 95086 b obtained with the Gemini Planet Imager between 2013 and 2016. A small but significant position angle change is detected at constant separation; the orbital motion is confirmed with literature measurements. Efficient Monte Carlo techniques place preliminary constraints on the orbital parameters of HD 95086 b. With 68% confidence, a semimajor axis of 61.7^{+20.7}_{-8.4} au and an inclination of 153.0^{+9.7}_{-13.5} deg are favored, with eccentricity less than 0.21. Under the assumption of a co-planar planet-disk system, the periastron of HD 95086 b is beyond 51 au with 68% confidence. Therefore HD 95086 b cannot carve the entire gap inferred from the measured infrared excess in the SED of HD 95086. We use our sensitivity to additional planets to discuss specific scenarios presented in the literature to explain the geometry of the debris belts. We suggest that either two planets on moderately eccentric orbits or three to four planets with inhomogeneous masses and orbital properties are possible. The sensitivity to additional planetary companions within the observations presented in this study can be used to help further constrain future dynamical simulations of the planet-disk system.Comment: Accepted for publication in ApJ