Outer space: Have We Already Been Visited by Aliens? - by Elizabeth Kolber

In “Extraterrestrial,” Loeb lays out his reasoning as follows. The only way to make sense of ‘Oumuamua’s strange acceleration, without resorting to some sort of undetectable outgassing, is to assume that the object was propelled by solar radiation—essentially, photons bouncing off its surface. And the only way the object could be propelled by solar radiation is if it were extremely thin—no thicker than a millimetre—with a very low density and a comparatively large surface area. Such an object would function as a sail—one powered by light, rather than by wind. The natural world doesn’t produce sails; people do. Thus, Loeb writes, “ ‘Oumuamua must have been designed, built, and launched by an extraterrestrial intelligence.”

Kepler, researchers recently concluded that η⊕ has a value somewhere between .37 and .6. Since there are at least four billion sunlike stars in the Milky Way, this means that somewhere between 1.5 billion and 2.4 billion planets in our galaxy could, in theory, harbor life. No one knows what fraction of potentially habitable planets are, in fact, inhabited, but, even if the proportion is trivial, we’re still talking about millions—perhaps tens of millions—of planets in the galaxy that might be teeming with living things.

At a public event a few years ago, Ellen Stofan, who at the time was NASA’s chief scientist and is now the director of the National Air and Space Museum, said that she believed “definitive evidence” of “life beyond earth” would be found sometime in the next two decades.

Read complete report at: Have We Already Been Visited by Aliens? | The New Yorker

ESA: Philae probe ‘sniffed’ organic building blocks of life, scientists say -by Victoria Bryan

European comet lander Philae “sniffed” organic molecules containing the carbon element that is the basis of life on Earth before its primary battery ran out and it shut down, German scientists said.

They said it was not yet clear whether they included the complex compounds that make up proteins. One of the key aims of the mission is to discover whether carbon-based compounds, and through them, ultimately, life, were brought to early Earth by comets.

The COSAC gas analysing instrument on Philae was able to “sniff” the atmosphere and detect the first organic molecules after landing, the DLR German Aerospace Center said.

The lander also drilled into the comet’s surface in its hunt for organic molecules, although it is unclear as yet whether Philae managed to deliver a sample to COSAC for analysis.

Also onboard the lander was the MUPUS tool to measure the density and thermal and mechanical properties of the comet’s surface. It showed the comet’s surface was not as soft as previously believed.

MUPUS could be used again if enough sunlight gets through to reload Philae’s batteries, which the scientists hope may happen as the comet approaches the sun.

Read more: Philae probe ‘sniffed’ organic building blocks of life, scientists say - The Globe and Mail

ESA: European Space Exploration - Great success - Europe's comet-chasing Rosetta probe reaches target

The Rosetta probe drew close to its study subject, the prosaically-named 67P/Churyumov-Gerasimenko comet, closely monitored by European Space Agency officials at mission control in Darmstadt, Germany.

The orbital entry on Wednesday was triggered by a firing of thrusters to bring the craft into the first of a series of "pyramidal" paths around the comet's nucleus, which has been likened to a rubber duck because of its odd shape.

ESA's Twitter account for the mission tweeted a photo of the comet's nucleus, along with a succession of greetings in different European languages.

The arrival marked a key moment for the 1.3-billion-euro ($1.76-billion) project examining the formation of the solar system. If all goes according to plan, Rosetta will carry out its first landing on the comet in November, sending a robot chemistry laboratory named Philae to the comet's surface.

Rosetta took off from Earth aboard an Ariane 5 rocket on March 2, 2004, from ESA's launchpad in French Guiana. The space agency has likened its unprecedented journey to a game of "cosmic billiards."

To reach its present position, the craft had to make four flybys of Earth and Mars, using the gravitational force of each as a slingshot. Rosetta then entered a 31-month hibernation period as the sun became too weak for its solar panels, coming back to life in January this year.

The latest maneuvers, to bring the probe within about 100 kilometers (60 miles) of the comet, have involved the craft making a series of braking maneuvers. The probe will eventually be steered into position some 10 kilometers from the nucleus' surface.

Astrophysicists believe comets, icy clusters left over from the formation of the planets 4.6 billion years ago, could be the key to understanding how the planets coalesced and formed around the sun. It is also thought they might harbor clues as to the source of the water that formed the Earth's oceans, as well as the origins of life itself.

Read more: Europe's comet-chasing Rosetta probe reaches target | News | DW.DE | 06.08.2014