The case for liquid water beneath the surface of Saturn's moon Enceladus has gotten a boost, with the discovery of salty ice grains that were blasted into space in the moon's gigantic plumes of ice and water vapour. The salt may have been leached from rocks in the moon's core by a reservoir of subsurface liquid water, which could be a potential habitat for life.



But the source of the plumes is still unknown. While some of the plume's ice grains are salty, another study released this week found that water vapour in the plumes seems to be salt-free, ruling out explosive geysers that directly blast salty water into space from elongated rifts called 'tiger stripes'.



This suggests the plumes are produced in a way that leaves most salt behind on the moon. "Our picture of [Enceladus's] subsurface must now be expanded to include the possibility of misty ice caverns floored with pools and channels of salty water, lurking beneath the tiger stripes," writes planetary scientist John Spencer in a commentary appearing this week in Nature. "What else make lurk in those salty pools, if they exist, remains to be seen." (Image: NASA/JPL/Space Science Institute)

A knob from a work light seems to have floated loose during the space shuttle Atlantis's May mission to repair the Hubble Space Telescope. After the shuttle landed, the knob was found wedged between the dashboard and an inner front window on the shuttle's fight deck.



NASA is investigating how best to remove the knob, which became stuck when the shuttle's cabin depressurised and shrank on landing.



If the window is deemed too dangerous to fly and must be replaced, Atlantis's scheduled November flight to the International Space Station could face a delay of up to six months. This could add pressure to NASA's already tight launch schedule. The agency aims to fly eight more missions before the shuttle is retired in 2010. (Image: NASA/Jim Ross)

An underground laboratory in the deepest mine in the US was officially dedicated this week in a ceremony that took place about 1.5 km below the surface of the Earth. The Sanford Underground Science and Engineering Laboratory lies beneath the Black Hills of South Dakota in a former gold mine known as Homestake. Later this year, physicists hope to install the Large Underground Xenon detector, which will use a chamber containing 350 kilograms of liquid xenon to search for weakly-interacting massive particles, one of the leading candidates for dark matter. The intervening earth will shield the detector from bombardment by charged particles called cosmic rays that are released by the sun and other cosmic bodies.



Before 13 May, the mine's 1.5-km level was under water. With more funding and water pumping, physicists hope to make Homestake Mine a national underground laboratory that is capable of hosting experiments down to a depth of 2.4 km. (Image: South Dakota Science and Technology Authority) Advertisement

Five days after launching, NASA's moon collider, the Lunar CRater Observation and Sensing Satellite (LCROSS), got the first glimpse of its quarry. This image was taken on 23 June, as LCROSS passed by the moon at a distance of 3200 km and used the moon's gravity to place it on course to collide with the moon.



LCROSS, as well as the spent upper stage of its launch vehicle, will crash into the moon's south pole in October. The resulting plumes of debris will be analysed for evidence of water ice, a potential resource for future lunar explorers. (Image: NASA)

Spaceport America, the planned headquarters for commercial space firm Virgin Galactic, broke ground late last week. The state of New Mexico, which will host the facility at a site about 70 kilometres north of the town Las Cruces, has invested $200 million in the project. Construction is expected to be complete by the end of 2010, around the same time that Virgin Galactic aims to begin offering $200,000 suborbital trips from the spaceport that will provide ticket holders about five minutes of weightlessness. (Illustration: Spaceport America Conceptual Images URS/Foster + Partners)

This ghostly ribbon is a remnant of a stellar explosion that was recorded by Chinese astronomers in 185 AD, making it the world's oldest recorded supernova. The remnant, dubbed RCW 86, sits 8200 light years away from Earth in the constellation Circinus.



A new study reveals that a fast-moving shock wave in RCW 86 has heated the gas behind it to some 30 million °C. This temperature is more than 10 times cooler than expected from the speed of the shock wave. Astronomers suspect the missing energy was used to accelerate charged particles, a fraction of which eventually hit Earth's atmosphere as cosmic rays. The researchers argue this process is sufficient to create the cosmic rays we see originating from the Milky Way. (Image: ESO/E. Helder/NASA/Chandra)