Nasa Cassini Image: Geyser on Saturn's Moon Enceladus

A geyser is seen on Saturn's moon Enceladus in this image by NASA's Cassini mission. 

Scientists used views like this to help them identify the source locations for individual jets spurting ice particles, water vapour and trace organic compounds from the surface of Enceladus.

Picture: REUTERS/NASA/JPL/Space Science Institute

NASA Astronaut Spots Steam Flowing from Island Volcano

A steam plume drifts away from a volcano on Pagan Island, part of the Commonwealth of the Northern Marianas.

CREDIT: NASA

An astronaut aboard the International Space Station spotted a steam plume flowing from the northernmost volcano on Pagan Island, part of the Commonwealth of the Northern Marianas.

The commonwealth is an island chain of volcanoes that form the margin between the Pacific Ocean (to the east) and the Philippine Sea (to the west).

Pagan is made up of two strato-volcanoes separated by an isthmus, and it is one of the more volcanically active islands in the Marianas.

The island was completely evacuated in 1981 when a large eruption forced the small Micronesian community to flee (PDF Report), according to a NASA statement.

GJ1214b, New Planet in Milky Way contains mainly Steam and Ice

The Picture shows a comparison between our Earth and GJ1214b.

Astronomers have discovered a new planet in our galaxy that is unlike any other found so far: Both the planet and its atmosphere are mostly water, though none of it is liquid.

The planet, GJ1214b, has a diameter 2.7 times that of Earth, and it weighs seven times as much.

It probably has much more water than Earth, in the form of steam and a peculiar high-temperature ice that exists at extremely high pressures and far less rock.

“There’s probably nothing too special about this planet itself,” said Zachory K. Berta, an astronomer at Harvard University who was involved with the research. The main thing, he added, is that “we have the opportunity to really see the density of the planet.”

He and his colleagues report their findings in The Astrophysical Journal.

To estimate the density and diameter, they measured the colour of the light from the star that shines through the planet’s atmosphere.

“We’re observing the sunset on this planet,” he said.

Though the planet was discovered with a ground-based telescope, the data that allowed Mr. Berta and his colleagues to estimate the planet’s mass and density was gathered by the Hubble Space Telescope.

Looking ahead, the researchers have two goals. The first is to learn more about the planet.

“We’re going to study this atmosphere,” Mr. Berta said, “and work on the details so we can really try to understand what’s going on.” The second goal is to find more planets.

Using the same techniques, the astronomers can study the atmosphere of other planets in detail, and Mr. Berta said a slightly smaller, slightly cooler planet might be capable of supporting life.

Jupiter's Moon Io: Watery Alien Planets Might be Stripped Dry by Gravity

Two sulphurous eruptions are visible on Jupiter's volcanic moon Io.

CREDIT: Galileo Project, JPL, NASA

Alien planets might experience tidal forces powerful enough to remove all their water, leaving behind hot, dry worlds like Venus, researchers said.

These findings might significantly affect searches for habitable exoplanets, scientists explained. Although some planets might dwell in regions around their star friendly enough for life as we know it, they could actually be lifelessly dry worlds.

The tides that we experience on Earth are caused by the gravitational pull of the moon and sun. Our tides are nothing compared to what we see elsewhere in the solar system — the gravitational pull Europa experiences from Jupiter leads to tidal forces roughly 1,000 times stronger than what Earth feels from our moon, flexing and heating Europa.

Heat is a major factor in how capable a planet might be of supporting life as we know it. What scientists call the habitable zone of a star is defined by whether liquid water can survive on its surface, given that life exists virtually wherever there is liquid water on Earth.

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

Herschel Finds Hot Water Vapour Around a Carbon Star

The red giant pulsating carbon star CW Leonis as seen by the PACS and SPIRE cameras and spectrometers on board Herschel.

The star itself is too bright to be seen well but it is releasing material in a violent stellar wind, some of which is seen in a 'bow shock' to the left of the star in this image.

Observations have shown that water vapor is being formed deep down near the surface of the star; a place where it was previously thought to be impossible to appear.

This means that the stellar wind must be much more 'clumpy' than previously foreseen, with some regions having a much weaker wind than others.

This allows ultraviolet light from interstellar space to reach the deeper, warmer regions and trigger the creation of water vapor. Credit: ESA / KU Leuven / LUTH / Observatoire de Paris