The James Webb Space Telescope About Webb's Orbit The James Webb Space Telescope will observe primarily the infrared light from faint and very distant objects. But all objects, including telescopes, also emit infrared light. To avoid swamping the very faint astronomical signals with radiation from the telescope, the telescope and its instruments must be very cold. Therefore, Webb has a large shield that blocks the light from the Sun, Earth, and Moon, which otherwise would heat up the telescope, and interfere with the observations. The L2 orbit is an elliptical orbit about the semi-stable second Lagrange point . In three of the solutions found by Lagrange, the bodies are in line (L1, L2, and L3); in the other two, the bodies are at the points of equilateral triangles (L4 and L5). In the case of Webb, the 3 bodies involved are the Sun, the Earth and the Webb. Other infrared missions have selected an L2 orbit, like WMAP and H2L2. Here are a few graphics that illustrate how far away Webb will be.
Découverte de trois exoplanètes potentiellement habitables Des astronomes de l'Observatoire européen austral (ESO) ont découvert dans la constellation du Scorpion un système solaire "doté d'une zone habitable bien remplie", avec trois "super-Terres" où les conditions seraient compatibles avec l'existence d'eau liquide. C'est autour de l'étoile Gliese 667C, d'une masse équivalente à un tiers de celle de notre Soleil, que l'équipe a fait cette trouvaille, à l'aide de l'instrument HARPS équipant le télescope de 3,6 mètres de l'ESO au Chili, indique l'organisation dans un communiqué. Le système de trois étoiles auquel appartient Gliese 667C est abondamment étudié par les scientifiques. Non seulement il est dans le voisinage immédiat de notre système solaire (22 années-lumière) mais il est aussi étonnamment similaire. Il représente donc un candidat de choix pour la recherche d'exoplanètes potentiellement habitables. Au total, les astronomes ont donc identifié au moins cinq planètes, deux autres demandant encore à être confirmées.
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Hubble Goes to the eXtreme to Assemble Farthest-Ever View of the Universe Hubble Goes to the eXtreme to Assemble Farthest-Ever View of the Universe Like photographers assembling a portfolio of best shots, astronomers have assembled a new, improved portrait of mankind's deepest-ever view of the universe. (Credit: NASA; ESA; G. Illingworth, D. Magee, and P. Called the eXtreme Deep Field, or XDF, the photo was assembled by combining 10 years of NASA Hubble Space Telescope photographs taken of a patch of sky at the center of the original Hubble Ultra Deep Field. The Hubble Ultra Deep Field is an image of a small area of space in the constellation Fornax, created using Hubble Space Telescope data from 2003 and 2004. The new full-color XDF image is even more sensitive, and contains about 5,500 galaxies even within its smaller field of view. Magnificent spiral galaxies similar in shape to our Milky Way and the neighboring Andromeda galaxy appear in this image, as do the large, fuzzy red galaxies where the formation of new stars has ceased. Related Link
Galaxy Zoo bulletins-electroniques.com : toute l'actualité technologique internationale en français, en accès libre et gratuit ! Observatory Astronomical observatories[edit] Ground-based observatories[edit] Ground-based observatories, located on the surface of Earth, are used to make observations in the radio and visible light portions of the electromagnetic spectrum. Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. For optical telescopes, most ground-based observatories are located far from major centers of population, to avoid the effects of light pollution. Specific research study performed in 2009 shows that the best possible location for ground-based observatory on Earth is Ridge A – a place in the central part of Eastern Antarctica.[3] This location provides the least atmospheric disturbances and best visibility. Radio observatories[edit] Beginning in 1930s, radio telescopes have been built for use in the field of radio astronomy to observe the Universe in the radio portion of the electromagnetic spectrum. Highest astronomical observatories[edit]
Laser propulsion Laser propulsion is a form of beam-powered propulsion where the energy source is a remote (usually ground-based) laser system and separate from the reaction mass. This form of propulsion differs from a conventional chemical rocket where both energy and reaction mass come from the solid or liquid propellants carried on board the vehicle. A laser launch Heat Exchanger Thruster system History[edit] The basic concepts underlying laser propulsion were first developed by Eugene Sanger and the Hungarian physicist Georgii Marx, with practical schemes being developed by Arthur Kantrowitz and Wolfgang Moekel in the 1970s.[1] Laser propulsion systems may transfer momentum to a spacecraft in two different ways. The forms described below are all of the second type, and could be described as thermal rockets. Forms[edit] There are several forms of laser propulsion. Ablative laser propulsion[edit] University of Alabama Huntsville Propulsion Research Center[3] has researched ALP.[4] CW plasma propulsion[edit]
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