Until recently the moon was regarded as bone dry – more desiccated than the most arid desert on Earth. That perception has changed recently with the discovery of significant amounts of ice near the lunar poles, first from satellite observations and then from the 2009 US mission to smash a probe into a shady crater.
A new study, published last week in the journal Science, shows that there is also far more water inside the moon than lunar geologists had realised. And it raises questions about the favoured theory for the origin of the moon: that it formed from material ejected by a huge impact in Earth’s early history.
The Nasa-funded researchers re-examined lunar material brought back to Earth by Apollo 17, the last manned expedition to the moon, using new microprobe technology that can detect the presence of chemicals on a microscopic scale. They focused on volcanic glass beads, coloured orange by their high titanium content, which formed about 3.7bn years ago when volcanic eruptions were still taking place on the moon. The beads contain “melt inclusions” – tiny samples of the moon’s molten magma that were trapped inside crystals before the eruption.
“In contrast to most volcanic deposits, the melt inclusions are encased in crystals that prevent the escape of water and other volatiles during eruption. These samples provide the best window we have on the amount of water in the interior of the moon,” says James Van Orman, a geologist at Case Western Reserve University.
The results show levels of water around 0.1 per cent. That is 100 times more than scientists had found earlier with simpler technology, and similar to the levels in solidified magma collected from mid-ocean ridges on Earth. Amounts of other volatile elements such as fluorine, chlorine and sulphur were also much higher than measured previously and close to those found in corresponding terrestrial material.
Although the study points to the Earth and moon having a common origin, it is not consistent with the giant impact theory, because the water would have been driven off into space as vapour by such a cataclysmic high-temperature event. So the authors say that ideas about the early solar system may need revising.
The study also gives a new twist to the origin of ice detected in craters at the lunar poles. The usual explanation is that the ice was brought to the moon by bombardment over billions of years from water-rich comets and meteoroids. But it now seems possible that some of the lunar ice came from within the moon – released by past volcanic eruptions.
The dark side of the universe
The biggest revolution in cosmology during the 1990s was the discovery that “dark energy” is pushing the universe apart at an ever increasing rate. Although most cosmologists quickly accepted dark energy, a few remain reluctant. The doubters may be convinced by a five-year survey of 200,000 galaxies, using data from the space-based Galaxy Evolution Explorer and the Anglo-Australian Telescope in New South Wales.
The observations, published in the Monthly Notices of the Royal Astronomical Society, confirm that dark energy is a constant force, affecting the universe uniformly and propelling its runaway expansion. They contradict an alternative theory that gravity changes its nature when acting at gigantic distances, becoming repulsive rather than attractive.
“These results tell us that dark energy is a cosmological constant, as Einstein proposed,” says Chris Blake of Swinburne University in Melbourne, the leader of the study. “If gravity were the culprit, then we would not be seeing these constant effects of dark energy.”
The discovery of dark energy came from an analysis of light from exploding stars called supernovae, which showed an accelerating expansion of the universe with time. The new survey provides two independent checks: both the distribution of galaxies through space and the growth of galactic clusters are consistent with dark energy.
It dominates our universe, making up 74 per cent of its mass-energy (mass and energy are interconvertible, in accordance with Einstein’s e=mc2 formula). The expansive effect overwhelms the power of gravity to pull things together, so the long-term outlook is for the universe to grow into a cosmic wasteland, with the galaxies so far apart that intelligent beings inside them would be unable to see other galaxies.
Although dark energy seems to be a fundamental property of empty space, physicists have not come up with an explanation for how it works.
Putting a new spin on wild silk moths
The world’s silk industry depends almost entirely on the domesticated mulberry silk moth Bombyx mori. Several other moth species around the world produce cocoons similar to Bombyx but they are (literally) hard to unravel and reel into long strands of silk.
Now scientists at Oxford University have discovered what makes wild silk difficult to spin – and found a chemical solution. Their study appears in the journal Biomacromolecules.
The problem is that the surface of wild silk cocoons is coated in a thin layer of the mineral calcium oxalate. The researchers discovered that a warm solution of the mild organic acid EDTA softened the cocoons enough for them to be reeled like farmed silk without reducing the strength and durability of the fibres.
“Unlike traditional ways of treating wild silk cocoons – such as degumming using pineapple juice, carding and hand spinning – our new method… does not damage the strands which give silk its sought-after properties,” says Tom Gheysens of Oxford.
His colleague Fritz Volrath adds: “While these experiments were with the wild silkmoth Gonometa postica, our findings suggest that other species could be treated and reeled using this method. This has the potential to bring a ‘wild silk revolution’ to places such as Africa and South America where wild silk is abundant but which are unsuited to domestic silk farming.”
The Amazon tribe that time forgot
Anthropologists and linguists have found many tribes that have no numerals or ways of counting beyond three. Now they have identified one Amazonian group, the Amondawa of Brazil, who do not even have a word for time.
Chris Sinha of the University of Portsmouth, the leader of the study, which was published in the journal Language and Cognition, says it is the first proof that time is not a universal human concept, as many have thought.
“For the Amondawa time does not exist in the same way as it does for us,” he says. “We can now say without doubt that there is at least one language and culture which does not have a concept of time as something that can be measured, counted or talked about in the abstract. The Amandawa live in a world of events rather than seeing events as being embedded in time.”
Their language has no words for concepts such as next week or last year – only distinctions between day and night and rainy and dry seasons. No one in the tribe has an age; instead people change their names to reflect their life status, so that a small child will give up his or her name to a newborn brother or sister.
The Amandawa were first contacted by the outside world in 1986 and continue to follow a traditional life of hunting, fishing and cultivating crops. But the coming of television and the Portuguese language threatens the tribal language with extinction, like thousands of others spoken by indigenous people.