zone of silence : ESA

Compact Payload Test Range for antenna testing

Satellite engineers learn to get used to the weirdly hushed interior of the Compact Payload Test Range in ESA’s ESTEC technical centre area, in Noordwijk, the Netherlands. In this zone of silence, satellite antennas are tested ahead of launch.

Metal walls form a ‘Faraday cage’ to block all external signals, isolating the facility from TV and radio broadcasts, aircraft and ship radars, and even mobile calls. Spiky foam cladding absorbs radio signals internally to create conditions simulating the infinite void of space.

Modern antennas are extremely complex, often transmitting highly shaped or multiple pencil beams rather than a single main beam. They must operate efficiently and be aligned to keep space missions connected with their home world, while being sensitive only to a carefully prescribed frequency range – and all this needs thorough testing on the ground.

The white surfaces in front of the ‘anechoic’ blue background are reflectors that pass signals from an illuminating antenna to the antenna under test. The reflectors transform the spherical expanding rays of the illuminator into a straight signal beam as if the illuminator were located far away in space.

To increase its capabilities, the Compact Payload Test Range (CPTR) was recently equipped with a state-of-the-art Near-Field Scanner (NFS) to measure the electromagnetic fields closely surrounding a test antenna. Via mathematics, the equivalent radiation at large distances is calculated.

This new set-up and test technique allow the measurement of larger antennas (up to 8 m in diameter) over a larger frequency range (0.4–50 GHz). Its first assignment will be to characterise the radiated performance of the next Galileo satellites ahead of their launch later this year.

Inside ESTEC’s Test Centre, the hybrid CPTR/NFS is equipped to test large antennas or complete satellites in cleanroom conditions. Its smaller Laboratory counterpart, the Compact Antenna Test Range, is also available to test smaller antennas quickly and easily in standard ‘ambient’ conditions. 

Source : ESA

Sun Erupts With Huge Flare! -Directed CME

Huge CME was launched from the sun on 11/4/2013, estimated to reach earth after 3 days .CMEs can affect electronic systems in satellites and on the ground. Experimental NASA research models show that the CME began at 3:36 a.m. EDT on April 11, leaving the sun at over 600 miles per second.

NASA’s Solar Dynamics Observatory captured this image of an M6.5 class flare at 3:16 am EDT on April 11, 2013. This image shows a combination of light in wavelengths of 131 and 171 Angstroms. Credit: NASA/SDO.

           NOAA's Space Weather Prediction Center (http://swpc.noaa.gov) is the United States Government official source for space weather forecasts, alerts, watches and warnings. NASA and NOAA – as well as the US Air Force Weather Agency (AFWA) and others -- keep a constant watch on the sun to monitor for space weather effects such as geomagnetic storms. With advance notification many satellites, spacecraft and technologies can be protected from the worst effects.

The magnetic field of sunspot AR1719 erupted on April 11th at 0716 UT, producing an M6-class solar flare. Coronagraph images from the Solar and Heliospheric Observatory show a CME emerging from the blast site of the M6.5 solar flare. Credit: NASA

Video : 

Published on 11 Apr 2013

STRONG SOLAR FLARE: The magnetic field of sunspot AR1719 erupted on April 11th at 0716 UT, producing an M6-class solar flare. NASA's Solar Dynamics Observatory recorded the explosion's extreme ultraviolet flash. Coronagraph images from the Solar and Heliospheric Observatory show a CME emerging from the blast site. The expanding cloud will probably deliver a glancing blow to Earth's magnetic field late on April 12th or more likely April 13th. Stay tuned for updates about this significant explosion.

           Solar flares are powerful bursts of radiation. Harmful radiation from a flare cannot pass through Earth's atmosphere to physically affect humans on the ground, however -- when intense enough -- they can disturb the atmosphere in the layer where GPS and communications signals travel. This disrupts the radio signals for as long as the flare is ongoing, anywhere from minutes to hours.

NASA’s Solar Dynamics Observatory captured this image of an M6.5 class flare at 3:16 EDT on April 11, 2013. This image shows a combination of light in wavelengths of 131 and 171 Angstroms. Credit: NASA/SDO.

Source  : NASA