ESA ATV-2: Johannes Kepler undocking from Space Station

Alors qu’il vient de se séparer de la Station spatiale internationale, l’ATV Kepler glisse lentement dans la nuit au terme d’une mission de 4 mois couronnée de succès.

Cette image a été prise le lundi 20 juin depuis la Station peu après le désamarrage qui s’est effectué à 16h46 heure de Paris. Le lendemain, l’ATV Kepler, piloté depuis le Centre Spatial Toulousain du CNES, s’est désintégré comme prévu vers 23h au-dessus de l’Océan Pacifique.

Picture credit: ESA/CNES

ESA Cassini-Huygens: Cassini samples the icy spray of Enceladus' water plumes

The NASA/ESA/ASI Cassini-Huygens mission has directly sampled the water plumes jetting into space from Saturn’s moon Enceladus.

The findings from these fly-throughs are the strongest evidence yet for the existence of large-scale saltwater reservoirs beneath the moon’s icy crust.

Enceladus’ water plumes shoot water vapour and tiny grains of ice into space.

They originate from the ‘tiger stripe’ surface fractures at the moon’s south pole, and create the faint E-ring, which traces the orbit of Enceladus around Saturn.

The Cassini spacecraft discovered the plumes in 2005 and more recently has been able to fly directly through them.

During three of Cassini’s passes in 2008 and 2009, the Cosmic Dust Analyser measured the composition of freshly ejected plume grains.

The icy particles hit the detector target at speeds of 6.5–17.5 km/s, and vaporised instantly. Electrical fields inside the instrument then separated the various constituents of the resulting impact cloud for analysis.

Far away from Enceladus, the data show that the ejected grains are relatively small and mostly salt-poor, closely matching the composition of the E-ring. Closer to the moon, however, Cassini has found that relatively large, salt-rich ice grains dominate.

It appears as though more than 99% of the total mass of ejected solids is in salt-rich grains, but most of these are heavy and fall back to the moon, so never make it into the E-ring.

The salt-rich particles have an ‘ocean-like’ composition which indicates that most, if not all, of the expelled ice comes from liquid saltwater, rather than from the icy surface of the moon.

When salty water freezes slowly, the salt is squeezed out, leaving pure water ice behind. So, if the plumes were coming from the surface ice, there should be very little salt in them.

“There currently is no plausible way to produce a steady outflow of salt-rich grains from solid ice across the tiger stripes other than from saltwater under Enceladus’ icy surface,” says Frank Postberg, Universität Heidelberg, Germany, who is the lead author on the paper announcing these results.

ESA - Cassini-Huygens - Cassini samples the icy spray of Enceladus' water plumes

Resveratrol: The Chemical in Red wine that improves your heart's health

It may soon be possible to receive the heart protecting abilities of red wine without having to drink a glass every day.

This is thanks to the synthesis of chemicals derived from resveratrol, the molecule believed to give wine its protective powers. The chemicals have the potential to fight many diseases, including cancer.

Plants make a huge variety of chemicals, called polyphenols, from resveratrol to protect themselves against invaders, particularly fungi but they only make tiny amounts of each chemical, making it extremely difficult for scientists to isolate and utilise them. 

The unstable nature of resveratrol has also hindered attempts at building new compounds from the chemical itself.

Scott Snyder at Columbia University in New York and his team have found a way around this: building polyphenols from compounds that resemble, but are subtly different to, resveratrol.

These differences make the process much easier. Using these alternative starting materials, they have made dozens of natural polyphenols, including vaticanol C, which is known to kill cancer cells (Nature, DOI: 10.1038/nature10197).

"It's like a recipe book for the whole resveratrol family," says Snyder. "We've opened up a whole casket of nature's goodies."

NASA Chandra Image: Pandora’s Cluster — Clash of the Titans

A team of scientists studying the galaxy cluster Abell 2744, nicknamed Pandora’s Cluster, have pieced together the cluster’s complex and violent history.

They did this using space and ground based telescopes, including the Hubble Space Telescope, the European Southern Observatory’s Very Large Telescope, the Japanese Subaru telescope, and NASA’s Chandra X-ray Observatory.

The giant galaxy cluster appears to be the result of a simultaneous pile-up of at least four separate, smaller galaxy clusters.

The crash took place over a span of 350 million years.

The galaxies in the cluster make up less than 5 percent of its mass. The gas (around 20 percent) is so hot that it shines only in X-rays (colored red in this image). The distribution of invisible dark matter (making up around 75 percent of the cluster’s mass) is colored here in blue.

Dark matter does not emit, absorb, or reflect light, but it makes itself apparent through its gravitational attraction. To pinpoint the location of this elusive substance the team exploited a phenomenon known as gravitational lensing. This is the bending of light rays from distant galaxies as they pass through the gravitational field created by the cluster.

The result is a series of telltale distortions in the images of galaxies in the background of the Hubble and VLT observations. By carefully analyzing the way that these images are distorted, it is possible to accurately map where the dark matter lies.


Chandra mapped the distribution of hot gas in the cluster.
The data suggest that the complex collision has separated out some of the hot gas (which interacts upon collision) and the dark matter (which does not) so that they now lie apart from each other, and from the visible galaxies.

Near the core of the cluster there is a “bullet” shape where the gas of one cluster collided with that of another to create a shock wave. The dark matter passed through the collision unaffected.

In another part of the cluster, galaxies and dark matter can be found, but no hot gas. The gas may have been stripped away during the collision, leaving behind no more than a faint trail.

The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center manages the telescope.

The Space Telescope Science Institute (STScI) conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington, D.C.

YouTube - Building MARS Rover Curiosity

How to pack a Mars rover: 4 days condensed into one minute:

NASA Hubble Image: Galaxy M82

The galaxy M82 is seen in this optical image taken by the Hubble Space Telescope.

The superimposed spectrum shows the molecular gas detected by the Large Millimeter Telescope.

Amongst others, different isotopes of carbon monoxide (CO), hydrogen cyanide (HCN) and methylacetylene (CH3C2H) and various hydrocarbons have been detected.

Picture: INAOE. REUTERS

Underwater Ecological Sculpture - Cancun

The VW beetle or "votcho" as it is known in Mexico is an iconic symbol and the classic shape was still in production until March 2003. Its rounded aerodynamic shape makes it perfectly suited to maintain stability underwater from strong currents and tropical storms

The Marine National Park off the coast of Cancun attracts about 750,000 visitors each year.



Other submerged sculptures at the underwater park by the British/Guyanese artist Jason de Caires Taylor include the Dream Collector.

Picture: Jason De Caires Taylor/Barcroft