After many years in development, Aladin – the Doppler wind lidar to be carried on the Aeolus satellite – is ready to be shipped from Toulouse, France, to the UK to be installed on the satellite in preparation for liftoff by the end of 2017. Aeolus will be the first satellite mission to probe the wind globally. These vertical slices through the atmosphere, along with information on aerosols and clouds, will advance our knowledge of atmospheric dynamics and contribute to climate research.
Its state-of-the art Aladin instrument incorporates two powerful lasers, a large telescope and very sensitive receivers. The laser generates ultraviolet light that is beamed towards Earth. This light bounces off air molecules and small particles such as dust, ice and droplets of water in the atmosphere. The fraction of light that is scattered back towards the satellite is collected by Aladin’s telescope and measured.
Mars as seen by the low-resolution Visual Monitoring Camera (VMC) on board ESA's Mars Express orbiter this week. This image was acquired on Wednesday, 4 August 2016, at 16:07:17 UTC (18:07:17 CEST) and is available, like all VMC images, in the camera's dedicated Flickr channel.
A gigantic ribbon of hot gas bursts upwards from the Sun, guided by a giant loop of invisible magnetism. This remarkable image was captured on 27 July 1999 by SOHO, the Solar and Heliospheric Observatory. Earth is superimposed for comparison and shows that from top to bottom the loop of gas, or prominence, extends about 35 times the diameter of our planet into space.
A prominence is an extension of gas that arches up from the surface of the Sun. Prominences are sculpted by magnetic fields that are generated inside the Sun, and then burst through the surface, propelling themselves into the solar atmosphere.
The Sun is predominantly made of plasma – an electrified gas of electrons and ions. Being electrically charged, the ions respond to magnetic fields. So when the magnetic loops reach up into the solar atmosphere, huge streams of plasma are attracted to fill them, creating the prominences that can last for weeks or months.
Spectacular prominences like this one are not particularly common, a few being detected each year. When they start to collapse, mostly the gas ‘drains’ down the magnetic field lines back into the Sun. Occasionally, however, they become unstable and release their energy into space. These eruptive prominences fling out a huge quantity of plasma that solar physicists call a coronal mass ejection. Solar flares are also associated with coronal mass ejections.
If this plasma hits Earth it can disrupt satellites, power grids and communications. It also causes the aurora to shine in the polar skies.
Taken by SOHO’s ultraviolet telescope, this image shows ionised helium at a temperature of about 70 000ºC.
A version of the image without the Earth for comparison can be found here.
Candidate coatings for a new space antenna undergoing testing at ESA’s technical heart in the Netherlands.
“Protective coatings safeguard antennas against temperature extremes or other environmental factors such as ultraviolet radiation,” explains antenna engineer Elena Saenz, performing the testing at ESA’s technical centre in Noordwijk.
“Working with industry, we were asked to evaluate several candidate coatings for the coming MetOp microwave imager – which sounds the atmosphere at various frequencies to gather data on rainfall, water vapour, temperature and clouds.
“The testing needs to measure the radio frequency behaviour of sample coatings across a very wide range of frequencies, from 18.7 GHz up to a maximum 191.3 GHz – checking, for instance, that they do not cause unacceptable signal losses.”
Feed horns send out radio signals to be reflected across the table to the coating and back again, to assess performance.
Two of the candidates proved most promising to coat the carbon-fibre reinforced polymer honeycomb microwave imager antenna. ESA’s antenna test facilities carry out around several of these kind of campaigns annually.
Higher frequencies were tested on the cleanroom tabletop system seen here, while testing for lower frequencies below 50 GHz was undertaken in ESA’s Compact Antenna Test Range, normally used for antenna testing but adaptable for materials testing as well.
OSIRIS narrow-angle camera image taken on 31 July 2016, when Rosetta was 9.9 km from the centre of Comet 67P/Churyumov–Gerasimenko. The scale is 0.16 m/pixel at the comet and the image measures about 328 m.
More details via the OSIRIS Image of the Day website.
Based in London, UK, Aoife is an artist working primarily with explosive media and the recipient of the first art&science@ESA residency, organised by Ars Electronica in partnership with ESA.
Candidate coatings for a new space antenna undergoing testing at ESA’s technical heart in the Netherlands. ESA's antenna test facilites were tasked with evaluating several candidate coatings for the coming MetOp microwave imager. Testing needs to measure the radio frequency behaviour of sample coatings across a very wide range of frequencies, from 18.7 GHz up to a maximum 191.3 GHz. Lower-frequency testing was carried out within the Microwave Material RF Characterization test facility inside the Compact Antenna Test Range, seen here, with higher-frequency testing performed in the (Sub)mm-wave Material RF Characterisation test facility.
Week In Images
1-5 August 2016