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Topic: ESA's Herschel space observatory end of mission
posted 03-07-2013 06:20 PM European Space Agency (ESA) release Herschel to finish observing soonESA's Herschel space observatory is expected to exhaust its supply of liquid helium coolant in the coming weeks after spending more than three exciting years studying the cool Universe. Herschel was launched on 14 May 2009 and, with a main mirror 3.5 m across, it is the largest, most powerful infrared telescope ever flown in space.A pioneering mission, it is the first to cover the entire wavelength range from the far-infrared to submillimetre, making it possible to study previously invisible cool regions of gas and dust in the cosmos, and providing new insights into the origin and evolution of stars and galaxies.In order to make such sensitive far-infrared observations, the detectors of the three science instruments - two cameras/imaging spectrometers and a very high-resolution spectrometer - must be cooled to a frigid -271*C, close to absolute zero. They sit on top of a tank filled with superfluid liquid helium, inside a giant thermos flask known as a cryostat.The superfluid helium evaporates over time, gradually emptying the tank and determining Herschel's scientific life. At launch, the cryostat was filled to the brim with over 2300 litres of liquid helium, weighing 335 kg, for 3.5 years of operations in space.Indeed, Herschel has made extraordinary discoveries across a wide range of topics, from starburst galaxies in the distant Universe to newly forming planetary systems orbiting nearby young stars.However, all good things must come to an end and engineers believe that almost all of the liquid helium has now gone.It is not possible to predict the exact day the helium will finally run out, but confirmation will come when Herschel begins its next daily 3-hour communication period with ground stations on Earth."It is no surprise that this will happen, and when it does we will see the temperatures of all the instruments rise by several degrees within just a few hours," says Micha Schmidt, the Herschel Mission Operations Manager at ESA's European Space Operations Centre in Darmstadt, Germany.The science observing programme was carefully planned to take full advantage of the lifetime of the mission, with all of the highest-priority observations already completed.In addition, Herschel is performing numerous other interesting observations specifically chosen to exploit every last drop of helium."When observing comes to an end, we expect to have performed over 22 000 hours of science observations, 10% more than we had originally planned, so the mission has already exceeded expectations," says Leo Metcalfe, the Herschel Science Operations and Mission Manager at ESA's European Space Astronomy Centre in Madrid, Spain.Herschel"We will finish observing soon, but Herschel data will enable a vast amount of exciting science to be done for many years to come," says Goeran Pilbratt, ESA's Herschel Project Scientist at ESA's European Space Research and Technology Centre in Noordwijk, the Netherlands."In fact, the peak of scientific productivity is still ahead of us, and the task now is to make the treasure trove of Herschel data as valuable as possible for now and for the future."Herschel will continue communicating with its ground stations for some time after the helium is exhausted, allowing a range of technical tests. Finally, in early May, it will be propelled into its long-term stable parking orbit around the Sun.
posted 04-29-2013 11:05 AM European Space Agency (ESA) release Herschel closes its eyes on the UniverseESA's Herschel space observatory has exhausted, as planned, its supply of liquid helium coolant, concluding over three years of pioneering observations of the cool Universe.The mission began with over 2300 litres of liquid helium, which has been slowly evaporating since the final top-up the day before Herschel's launch on 14 May 2009.The evaporation of the liquid helium was essential to cool the observatory's instruments to close to absolute zero, allowing Herschel to make highly sensitive scientific observations of the cold Universe until today.The confirmation that the helium is finally exhausted came this afternoon at the beginning of the spacecraft's daily communication session with its ground station in Western Australia, with a clear rise in temperatures measured in all of Herschel's instruments."Herschel has exceeded all expectations, providing us with an incredible treasure trove of data that will keep astronomers busy for many years to come," says Prof. Alvaro Giménez, ESA's Director of Science and Robotic Exploration.Herschel has made over 35 000 scientific observations, amassing more than 25 000 hours of science data from about 600 observing programmes. A further 2000 hours of calibration observations also contribute to the rich dataset, which is based at ESA's European Space Astronomy Centre, near Madrid in Spain.The archive will become the legacy of the mission. It is expected to provide even more discoveries than have been made during the lifetime of the Herschel mission."Herschel's ground-breaking scientific haul is in no little part down to the excellent work done by European industry, institutions and academia in developing, building and operating the observatory and its instruments," adds Thomas Passvogel, ESA's Herschel and Planck Project Manager.The mission resulted in a number of technological advancements applicable to future space missions and potential spin-off technologies. The mission saw the development of advanced cryogenic systems, the construction of the largest telescope mirror ever flown in space, and the utilisation of the most sensitive direct detectors for light in the far-infrared to millimetre range. Manufacturing techniques enabling the Herschel mission have already been applied to the next generation of ESA's space missions, including Gaia."Herschel has offered us a new view of the hitherto hidden Universe, pointing us to previously unseen processes of star birth and galaxy formation, and allowing us to trace water through the Universe from molecular clouds to newborn stars and their planet-forming discs and belts of comets," says Göran Pilbratt, ESA's Herschel Project Scientist. Star birthHerschel's stunning images of intricate networks of dust and gas filaments within our Milky Way Galaxy provide an illustrated history of star formation. These unique far-infrared observations have given astronomers a new insight into how turbulence stirs up gas in the interstellar medium, giving rise to a filamentary, web-like structure within cold molecular clouds.If conditions are right, gravity then takes over and fragments the filaments into compact cores. Deeply embedded inside these cores are protostars, the seeds of new stars that have gently heated their surrounding dust to just a few degrees above absolute zero, revealing their locations to Herschel's heat-sensitive eyes.Following the water trailOver the first few million years in the life of newborn stars, the formation of planets can be followed in the dense discs of gas and dust swirling around them. In particular, Herschel has been following the trail of water, a molecule crucial to life as we know it, from star-formation clouds to stars to planet-forming discs.Herschel has detected thousands of Earth ocean's worth of water vapour in these discs, with even greater quantities of ice locked up on the surface of dust grains and in comets.Closer to home, Herschel has also studied the composition of the water-ice in Comet Hartley-2, finding it to have almost exactly the same isotopic ratios as the water in our oceans.These findings fuel the debate about how much of Earth's water was delivered via impacting comets. Combined with the observations of massive comet belts around other stars, astronomers hope to understand whether a similar mechanism could be at play in other planetary systems, too.Galaxies across the UniverseHerschel has also contributed to our knowledge of star formation on the grandest scales, spanning much of cosmic space and time. By studying star formation in distant galaxies, it has identified many that are forming stars at prodigious rates, even in the early years of the Universe's 13.8 billion-year life.These intense star-forming galaxies produce hundreds to thousands of solar masses' worth of stars each year. By comparison, our own Milky Way galaxy produces the equivalent of only one Sun-like star per year on average.How galaxies can support star formation on such massive scales during the first few billions of years of the Universe's existence is an unsolved mystery for scientists studying galaxy formation and evolution. Herschel observations are hinting that when the Universe was young, galaxies had much more gas to feed from, enabling high rates of star formation even in the absence of the collisions between galaxies normally needed to spark these spectacular bouts of star birth."Although this is the end of Herschel observing, it is certainly not the end of the mission - there are plenty more discoveries to come," says Dr Pilbratt."We will now concentrate on making our data accessible in the form of the best possible maps, spectra and various catalogues to support the work of present and future astronomers. Nevertheless we're sad to see the end of this phase: thank you, Herschel!"
SkyMan1958Member Posts: 355From: CA.Registered: Jan 2011
posted 04-29-2013 11:53 AM Here's the BBC's article on the end of Herschel. It has some nice pictures, including an intriguing one of gas rings/layers around Betelgeuse. The billion-euro Herschel observatory has run out of the liquid helium needed to keep its instruments and detectors at their ultra-low functioning temperature.This equipment has now warmed, meaning the telescope cannot now see the sky.Herschel, which was sensitive to far-infrared and sub-millimetre light, was launched in 2009 to study the birth of stars and the evolution of galaxies.Its 3.5m mirror and three state-of-the-art instruments made it the most powerful observatory of its kind ever put in space. All times are CT (US)next newest topic | next oldest topic