Category Archives: ESA

Polar Vortex

polarvortexvenus

The polar vortex of Venus – south pole.

ESA has a nice video version located here.

Credit: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA/Univ. Oxford

ESA’s caption:

This ghostly puff of smoke is actually a mass of swirling gas and cloud at Venus’ south pole, as seen by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) aboard ESA’s Venus Express spacecraft.

Venus has a very choppy and fast-moving atmosphere – although wind speeds are sluggish at the surface, they reach dizzying speeds of around 400 km/h at the altitude of the cloud tops, some 70 km above the surface. At this altitude, Venus’ atmosphere spins round some 60 times faster than the planet itself. This is very rapid; even Earth’s fastest winds move at most about 30% of our planet’s rotation speed. Quick-moving Venusian winds can complete a full lap of the planet in just four Earth days.

Polar vortices form because heated air from equatorial latitudes rises and spirals towards the poles, carried by the fast winds. As the air converges on the pole and then sinks, it creates a vortex much like that found above the plughole of a bath. In 1979, the Pioneer Venus orbiter spotted a huge hourglass-shaped depression in the clouds, some 2000 km across, at the centre of the north polar vortex. However, other than brief glimpses from the Pioneer Venus and Mariner 10 missions in the 1970s, Venus’ south pole had not been seen in detail until ESA’s Venus Express first entered orbit in April 2006.

One of Venus Express’ first discoveries, made during its very first orbit, was confirming the existence of a huge atmospheric vortex circulation at the south pole with a shape matching the one glimpsed at the north pole.

This south polar vortex is a turbulent mix of warming and cooling gases, all surrounded by a ‘collar’ of cool air. Follow-up Venus Express observations in 2007, including this image, showed that the core of the vortex changes shape on a daily basis. Just four hours after this image the vortex looked very different and a day later it had morphed into a squashed shape unrecognisable from the eye-like structure here.

A video of the vortex, made from 10 images taken over a period of five hours, can be seen here. The vortex rotates with a period of around 44 hours.

The swirling region shown in this VIRTIS image is about 60 km above the planet’s surface. Venus’ south pole is located just up and to the left of the image centre, slightly above the wispy ‘eye’ itself.

This image was obtained on 7 April 2007 at a wavelength of 5.02 micrometres. It shows thermal-infrared emission from the cloud tops; brighter regions like the ‘eye’ of the vortex are at lower altitude and therefore hotter.

 

Lunar Pox

lunarpox

Great title from ESA for this image of the Lunar north pole from the SMART-1 spacecraft.  It’s been a long time since I posted a SMART-1 image!

ESA’s description (included below) talks a lot about the lighting.  The pattern of the craters sort of looks like a spiral to me and that might be the lighting too.

Image: ESA/SPACE-X (Space Exploration Institute). Acknowledgments: J. Manuel Fonseca, M. Costa & A. Mora (UNINOVA); B. Grieger & M. Almeida (ESA)

 

ESA’s caption:The pockmarked landscape captured in this image from ESA’s SMART-1 mission is the surface of our Moon. Some of the many craters scattered across the lunar surface are clearly visible, records of the many impacts that have plagued it.

At the very centre of this image is the lunar north pole, captured in detail during ESA’s mission. The image shows the characteristic craters of the Moon, present in all shapes and sizes. The largest in view is Rozhdestvenskiy, sandwiched between Hermite to the northeast and Plaskett to the southwest.

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ESA Honors Team Members

rosettahonor1

Very nice.  The original caption (below) included a close up of the feature.  You can see it by clicking the image above.

The caption:

Scientists from the European Space Agency’s Rosetta team have honored two late team members by naming comet features after them. The comet is 67P/Churyumov-Gerasimenko, where the mission successfully landed a probe.

One of the features is shown here in these Rosetta images, with the picture on the right being a close-up view. The “C. Alexander Gate” is found on the comet’s smaller lobe, and is dedicated to Claudia Alexander, the U.S. project scientist from NASA’s Jet Propulsion Laboratory, Pasadena, California, who passed away in July of this year.

Image credit : ESA’s comet viewer

Rosetta is a European Space Agency mission with contributions from its member states and NASA. Rosetta’s Philae lander is provided by a consortium led by the German Aerospace Center, Cologne; Max Planck Institute for Solar System Research, Gottingen; French National Space Agency, Paris; and the Italian Space Agency, Rome. NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the U.S. participation in the Rosetta mission for NASA’s Science Mission Directorate in Washington.