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  • richardmitnick 3:01 pm on February 19, 2014 Permalink | Reply
    Tags: , , , Canadian Space Agency, , ,   

    From ESA: ” MIRI keeps cool under low pressure” 

    ESASpaceForEuropeBanner
    European Space Agency

    19-Feb-2014
    No Writer Credit

    The Mid-Infrared Instrument (MIRI) on JWST has performed beautifully during its first cryo-vacuum test campaign carried out at NASA’s Goddard Space Flight Center towards the end of last year. An examination of data recorded during those tests confirms that the instrument is in good health and performing well.

    In August last year preparations began for the first ISIM (Integrated Science Instrument Module) test campaign to be performed in a vacuum and at cryogenic temperatures. Fitted with two instruments – MIRI and FGS/NIRISS (the Fine Guidance Sensor / Near-InfraRed Imager and Slitless Spectrograph) – ISIM was installed in the Space Environment Simulator (SES), a large cryogenic test chamber at Goddard. The doors to the chamber were closed on 29 August and after about 5 days the vacuum (approximately 10-6 mbar) was achieved, ISIM and the instruments were checked to be functioning and in good shape, and the cool-down then began.

    NASA Webb MIRI
    MIRI

    NASA Webb Fine Guidance
    FGS/NIRISS

    isim
    ISIM with MIRI and FGS/NIRISS, mounted on a test rig Credit: NASA / Chris Gunn

    ses
    ISIM inside the SES chamber at Goddard. Credit: NASA / Chris Gunn

    cryo
    The cryocooler under development for MIRI.
    Credit: Northrop Grumman

    Nearly twenty days later, the ISIM reached a temperature of -233 °C (40.15 K) – the same temperature it will experience in space. However, this temperature is not low enough for the advanced detectors on MIRI. To ensure that the detectors are not blinded by temperature-driven parasitic light and currents, astronomers require the instrument to be cooled down to around -266 °C. This is barely seven degrees above absolute zero – the latter being the lowest temperature possible, as defined by the laws of physics. To achieve this level of cooling, a dedicated cooling system, called the MIRI cryocooler is being developed by NASA JPL.

    During the almost three-week cool down of MIRI, team members on-site at Goddard, across Europe and elsewhere in the US monitored the health of the instrument, 24 hours a day, seven days a week.

    Once the Optical Telescope Simulator (OSIM), ISIM, MIRI and FGS/NIRISS all reached their operating temperatures, the scientists and engineers resumed their tests, constantly monitoring the state of the instruments, as well as conducting their experiments and analysing the data.
    Left: Thermal and vacuum test rig for ISIM. Credit: NASA / Chris Gunn.

    osim
    Erin Wilson is seen here preparing the JWST OSIM for environmental testing. Image credits: NASA / Chris Gunn

    Every indication showed that MIRI performed well, however, not even scientific experiments deep in the Goddard cryogenic test chamber are immune from external perturbations and on 1 October all testing was put on hold as the American government shut down.

    Once the furlough ended, testing started again on 17 October. To reduce the impact of the unscheduled ‘break’, the sequence of tests was revised and heavily streamlined. The most critical activities were given the highest priorities and tested accordingly.

    Despite this interruption, and due to the great efforts from all of the teams, the tests at operating temperature were successfully completed on 29 October and all of the primary goals of the first ISIM test campaign were reached. Warm-up then started and was finished in the week of 11 November, after which this first ISIM cryo-vacuum test campaign was officially declared complete.

    This was the first time MIRI could be tested at its operating temperature since the instrument-level testing at RAL in Europe in 2011. The data gathered by the MIRI team have shown that the instrument performed beautifully and is in good health.

    About JWST

    The James Webb Space Telescope (JWST) will be a general-purpose observatory with a 6.5-m telescope optimised for infrared observations and a suite of four astronomical instruments capable of addressing many of the outstanding issues in astronomy. The primary aim is to examine the first light in the Universe – those objects which formed shortly after the Big Bang. Further aims include: looking at how galaxies form; the birth of stars; and the search for protoplanetary systems and the origin of life, including the study of exoplanets. JWST is a joint project of NASA, ESA and the Canadian Space Agency. It is scheduled for launch in 2018 by an Ariane 5 and will operate approximately 1.5 million kilometres from the Earth in an orbit around the second Lagrange point of the Sun-Earth system, L2.

    About MIRI

    The Mid-Infrared Instrument (MIRI) is one of four instruments on JWST. MIRI will provide direct imaging, medium- and low-resolution spectroscopy, and coronagraphic imaging. It is expected to make important contributions in all of the primary science aims of JWST. MIRI was developed as a partnership between Europe and the USA – the main partners are a consortium of nationally funded European institutes (the MIRI European Consortium), the Jet Propulsion Laboratory (JPL), ESA, and NASA’s Goddard Space Flight Center (GSFC).

    See the full article here.

    The European Space Agency (ESA), established in 1975, is an intergovernmental organization dedicated to the exploration of space, currently with 19 member states. Headquartered in Paris, ESA has a staff of more than 2,000. ESA’s space flight program includes human spaceflight, mainly through the participation in the International Space Station program, the launch and operations of unmanned exploration missions to other planets and the Moon, Earth observation, science, telecommunication as well as maintaining a major spaceport, the Guiana Space Centre at Kourou, French Guiana, and designing launch vehicles. ESA science missions are based at ESTEC in Noordwijk, Netherlands, Earth Observation missions at ESRIN in Frascati, Italy, ESA Mission Control (ESOC) is in Darmstadt, Germany, the European Astronaut Centre (EAC) that trains astronauts for future missions is situated in Cologne, Germany, and the European Space Astronomy Centre is located in Villanueva de la Cañada, Spain.


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  • richardmitnick 12:37 pm on September 13, 2011 Permalink | Reply
    Tags: , , Canadian Space Agency, , , ,   

    From NASA: “NASA’s Webb Telescope Completes Mirror-Coating Milestone” 

    09.13.11
    Trent J. Perrotto
    Headquarters, Washington

    Lynn Chandler
    NASA’s Goddard Space Flight Center, Greenbelt, Md.

    “NASA’s James Webb Space Telescope has reached a major milestone in its development. The mirrors that will fly aboard the telescope have completed the coating process at Quantum Coating Inc. in Moorestown, N.J.

    The telescope’s mirrors have been coated with a microscopically thin layer of gold, selected for its ability to properly reflect infrared light from the mirrors into the observatory’s science instruments. The coating allows the Webb telescope’s “infrared eyes” to observe extremely faint objects in infrared light. Webb’s mission is to observe the most distant objects in the universe.

    ‘Finishing all mirror coatings on schedule is another major success story for the Webb telescope mirrors,’ said Lee Feinberg, NASA Optical Telescope Element manager for the Webb telescope at the agency’s Goddard Space Flight Center in Greenbelt, Md. ‘These coatings easily meet their specifications, ensuring even more scientific discovery potential for the Webb telescope.”

    The Webb telescope has 21 mirrors, with 18 mirror segments working together as one large 21.3-foot (6.5-meter) primary mirror. The mirror segments are made of beryllium, which was selected for its stiffness, light weight and stability at cryogenic temperatures. Bare beryllium is not very reflective of near-infrared light, so each mirror is coated with about 0.12 ounce of gold.

    The last full size (4.9-foot /1.5-meter) hexagonal beryllium primary mirror segment that will fly aboard the observatory recently was coated, completing this stage of mirror production.

    i2
    The first six flight ready James Webb Space Telescope’s primary mirror segments are prepped to begin final cryogenic testing at NASA’s Marshall Space Flight Center in Huntsville, Ala. Credit: NASA/Chris Gunn

    The Webb telescope is the world’s next-generation space observatory and successor to the Hubble Space Telescope. The most powerful space telescope ever built, the Webb telescope will provide images of the first galaxies ever formed, and explore planets around distant stars. It is a joint project of NASA, the European Space Agency and the Canadian Space Agency.”

    See the full article here.

     
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