Time filter

Source Type

London, United Kingdom

Tinetti G.,University College London | Beaulieu J.P.,CNRS Paris Institute of Astrophysics | Henning T.,Max Planck Institute for Astronomy | Meyer M.,ETH Zurich | And 131 more authors.
Experimental Astronomy | Year: 2012

A dedicated mission to investigate exoplanetary atmospheres represents a major milestone in our quest to understand our place in the universe by placing our Solar System in context and by addressing the suitability of planets for the presence of life. EChO-the Exoplanet Characterisation Observatory-is a mission concept specifically geared for this purpose. EChO will provide simultaneous, multi-wavelength spectroscopic observations on a stable platform that will allow very long exposures. The use of passive cooling, few moving parts and well established technology gives a low-risk and potentially long-lived mission. EChO will build on observations by Hubble, Spitzer and ground-based telescopes, which discovered the first molecules and atoms in exoplanetary atmospheres. However, EChO's configuration and specifications are designed to study a number of systems in a consistent manner that will eliminate the ambiguities affecting prior observations. EChO will simultaneously observe a broad enough spectral region-from the visible to the mid-infrared-to constrain from one single spectrum the temperature structure of the atmosphere, the abundances of the major carbon and oxygen bearing species, the expected photochemically-produced species and magnetospheric signatures. The spectral range and resolution are tailored to separate bands belonging to up to 30 molecules and retrieve the composition and temperature structure of planetary atmospheres. The target list for EChO includes planets ranging from Jupiter-sized with equilibrium temperatures Teq up to 2,000 K, to those of a few Earth masses, with Teq \u223c 300 K. The list will include planets with no Solar System analog, such as the recently discovered planets GJ1214b, whose density lies between that of terrestrial and gaseous planets, or the rocky-iron planet 55 Cnc e, with day-side temperature close to 3,000 K. As the number of detected exoplanets is growing rapidly each year, and the mass and radius of those detected steadily decreases, the target list will be constantly adjusted to include the most interesting systems. We have baselined a dispersive spectrograph design covering continuously the 0. 4-16 μm spectral range in 6 channels (1 in the visible, 5 in the InfraRed), which allows the spectral resolution to be adapted from several tens to several hundreds, depending on the target brightness. The instrument will be mounted behind a 1. 5 m class telescope, passively cooled to 50 K, with the instrument structure and optics passively cooled to \u223c45 K. EChO will be placed in a grand halo orbit around L2. This orbit, in combination with an optimised thermal shield design, provides a highly stable thermal environment and a high degree of visibility of the sky to observe repeatedly several tens of targets over the year. Both the baseline and alternative designs have been evaluated and no critical items with Technology Readiness Level (TRL) less than 4-5 have been identified. We have also undertaken a first-order cost and development plan analysis and find that EChO is easily compatible with the ESA M-class mission framework. © 2012 Springer Science+Business Media B.V. Source

Barbera M.,National institute for astrophysics | Argan A.,National institute for astrophysics | Bozzo E.,Science Data Center for Astrophysics | Branduardi-Raymont G.,MSSL | And 16 more authors.
Journal of Low Temperature Physics | Year: 2016

ATHENA is the L2 mission selected by ESA to pursue the science theme “Hot and Energetic Universe.” One of the two focal plane instruments is the X-ray Integral Field Unit, an array of TES microcalorimeters operated at T(Formula presented.) 100 mK. To allow the X-ray photons focused by the telescope to reach the detector, windows have to be opened on the cryostat thermal shields. X-ray transparent filters need to be mounted on these open windows to attenuate the IR radiation from warm surfaces, to attenuate RF electromagnetic interferences on TES sensors and SQUID electronics, and to protect the detector from contamination. This paper reviews the ongoing activities driving the design of the X-IFU thermal filters. © 2016 Springer Science+Business Media New York Source

Paranicas C.,APL | Roussos E.,MPS | Krupp N.,MPS | Kollmann P.,MPS | And 8 more authors.
Planetary and Space Science | Year: 2012

We characterize the relative importance of energetic electrons and protons to the weathering of five of the inner satellites of Saturn. To do this, we present data from the Magnetospheric Imaging Instrument on the Cassini spacecraft, some of which is averaged over the whole mission to date. We also compute averaged proton and electron energy spectra relevant to the distances of these inner satellites. Where data are available, we estimate the power per unit area into a satellites surface. For electron energy deposition into satellite leading hemispheres, we find the power per unit area is greatest at Mimas and falls off with distance from Saturn. Using fluxes of 150 MeV protons detected within the sweeping corridors of Mimas and Enceladus, we find the corresponding deposition would be about 2×10 8 and 3.7×10 7 eV/cm 2 s. © 2011 Elsevier Ltd. All rights reserved. Source

Mereghetti S.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Tiengo A.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Esposito P.,Istituto di Astrofisica Spaziale e Fisica Cosmica | Vianello G.,Istituto di Astrofisica Spaziale e Fisica Cosmica | And 9 more authors.
Advances in Space Research | Year: 2011

We describe the results obtained with Target of Opportunity observations of the galactic sources SGR 1627-41 and 1E 1547-5408. These two transients show several similarities supporting the interpretation of Anomalous X-ray Pulsars and Soft Gamma-ray Repeaters as a single class of strongly magnetized neutron stars. © 2010 COSPAR. Published by Elsevier Ltd. All rights reserved. Source

Paranicas C.,APL | Roussos E.,Max Planck Institute for Solar System Research | Decker R.B.,APL | Johnson R.E.,University of Virginia | And 11 more authors.
Icarus | Year: 2014

We have modeled an electron precipitation pattern expected on Mimas, Tethys, and Dione, using two different approaches. In the first approach, we adapt a previously developed model to compute an integrated energy flux into the surfaces of Mimas, Tethys, and Dione. This is a guiding-center, bounce-averaged model. In the second approach, we track individual particles in an electromagnetic field for an inert or slightly magnetized satellite. This second approach allows us to include the effects of electron pitch angle and gyrophase on the weathering pattern. Both methods converge on an enhanced dose pattern on each satellite's leading hemisphere that is lens-shaped. We also present mission-averaged electron energy spectra obtained near these satellites by Cassini's Magnetosphere Imaging Instrument (MIMI). These data are interpreted using our current understanding of both the environment and the instrument's response. Fits to the data are integrated to find an energy flux into each satellite's surface, as a function of longitude and latitude. Using positions on the moon accessible to energetic electrons from the modeling and the integrated energy flux based on data, we find lens patterns that fall off with increasing moon latitude. The predicted patterns are qualitatively consistent with some but not all of the optical observations made of these hemispheres. © 2014 Elsevier Inc. Source

Discover hidden collaborations