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Successful Planck RF Telescope Test At 320 GHz
Cannes, France (SPX) Oct 25, 2007 This article reports on the recently concluded Planck Radio Frequency Qualification Model (RFQM) test campaign in the Thales Alenia Space Compact Antenna Test Range (CATR) facility, Cannes, France. The campaign gave to engineers and scientists confirmation that the planned RF verification method of the alignment of the Flight Model (FM) telescope is completely operational and can be performed with confidence on the FM spacecraft early next year. The success of this test campaign is due to exceptional team work from industry (Thales Alenia Space), ESA and the Planck Science community. It should be noted that the ESA Planck project has been strongly supported by personnel from the technical directorate at ESTEC, both in the definition and execution of the campaign and antenna RF predictions. This overall excellent collaboration has allowed an innovative testing method to be successfully implemented.
Testing Method The diode is "modulated", with a bias voltage between two states corresponding to reflective and absorbing for the 320 GHz illuminating signal. The purpose of the test is to derive, from the difference between these two reflective states, the antenna pattern. To accomplish this, a quasi-optical illuminator (QOI) was designed and implemented for the test. It is placed at the feed position of the CATR. The QOI can be described in RF terms as a circulator utilizing quasi-optical techniques allowing two-way reflectivity measurements. An additional essential configuration of the CATR was the implementation of frequency sweep operation of the quasi-optical illuminator modules. The transmitter and receiver were swept through a 1 GHz bandwidth, allowing a range depth resolution of a few cm to be achieved.
Measurements and Results The measurement results achieved match extremely well with predictions. This confirms that the technique can and will be applied as a final alignment check on the Planck telescope on the FM spacecraft early next year. Community Email This Article Comment On This Article Related Links Space Telescope News and Technology at Skynightly.com
NASA Concludes Successful FUSE Mission
Greenbelt MD (SPX) Oct 19, 2007After an eight-year run that gave astronomers a completely new perspective on the universe, NASA has concluded the Far Ultraviolet Spectroscopic Explorer mission. The satellite, known as FUSE, became inoperable in July when the satellite lost its ability to point accurately and steadily at areas of interest. NASA will terminate the mission Oct. 18. "FUSE accomplished all of its mission goals and more," said Alan Stern, associate administrator for the Science Mission Directorate at NASA Headquarters, Washington. |
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