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More evidence of water on Mars
NEW observations by Mars Odyssey and Mars Global Surveyor (another Nasa probe that is mapping Mars) suggest the planet’s north pole has about one third more underground ice than the south. It is the best evidence found so far.
Beneath a shallow crust of dry soil, there appears to be a layer of permanently frozen ground that is up to 75 per cent ice.
“If the conditions were warmer in the past, as they probably were, it may have led to the ice melting to form water which would be much more conducive to the presence of life,” says William Boynton, one of a team of Russian and American astronomers behind the discovery.
The finding is exciting not just because it increases the possibility that microbial life could have evolved on a planet other than Earth. It may also make human exploration of Mars more feasible because astronauts sent to the planet would need a source of water during their stay.
“From the point of view of human missions to Mars, it could be an outstanding discovery,” says Bo Maxwell of the UK branch of the Mars Society.
“The big question is exactly how deep these deposits are and how pure they are.”
The best evidence so far rests on the distinctive chemical signature of hydrogen in water, detected by an instrument on Mars Odyssey. Landing a robotic space probe near one of the Martian poles to dig for ice could settle the argument, once and for all.
“To land on the ice and look for organic material that might be indicative of past life,” says Boynton, of the Lunar and Planetary Laboratory, University of Arizona, Tucson.
The latest research, reported in the journal Science, comes as Nasa prepares to launch the second of its Mars Exploration Rovers, named Opportunity.
The robotic explorer is following in the footsteps of its twin, Spirit, and Europe’s Mars Express and Beagle 2 mission.
Spirit, Opportunity and Beagle will touch down on Mars after a six-month voyage. They are all heading for the mid-latitudes of Mars rather than the polar regions.
Nevertheless, the news is bound to be greeted with enthusiasm by the project teams, particularly Beagle, which carries experiments to search for life.
‘Power nap’ may boost learning
Grabbing an hour’s sleep during the day may be as beneficial as a whole night in bed, according to scientists. But the “power-nap” only works if the sleep is of the right quality, say the experts from Harvard University, US.
And experts say that a full night’s sleep is still necessary for many vital body functions, even though a short sleep may boost learning and memory.
The Harvard research, published in the journal Nature Neuroscience, compared the learning and memory skills of two groups of people during a single day, and again the following morning. One group was told not to sleep at all during the day, and, as expected, their performance tailed off into the afternoon and evening. However, the other volunteers were allowed to have an hour or 90 minutes nap at 2pm.
The researchers tested the brainwaves of the “nappers” to check the quality of their sleep.
They were looking for two different sleep phases, slow wave sleep, and rapid eye movement, which is normally associated with dreaming. Those whose sleep involved both phases fared significantly better than those who had no sleep when given the learning test later in the day.
Volunteers who never reached rapid eye movement sleep did not perform as well, although even this “poor-quality” sleep did prevent some of the deterioration in performance.
Remarkably, over 24 hours, the performance of those who took a good-quality “power-nap” was as good as volunteers in previous studies who were tested after two full nights’ sleep.
The researchers wrote: “From the perspective of behavioural improvement, a nap is as good as a night of sleep for learning on this perceptual task.”
Dr Derk-jan Dijk, from the Sleep Research Centre at the University of Surrey, said that there was increasing evidence that a combination of “short wave sleep” and REM sleep was important for learning and memory. However, he added: “We should not conclude that we can do with just a nap.
“Other research has suggested that people given six hours of sleep a night over a sustained period find it extremely detrimental.”
Seven new species found
In a largely unexplored valley, groups of students found two frog species, two snakes, two toads, a lizard and an owl not recorded before in Bolivia.
Experts say their discoveries suggest the country’s overall variety of species may be greater than previously thought.
The finds were made in 2001 by students from the universities of Oxford and Glasgow, UK, and the University Major San Simon, Bolivia. Their expedition, Yungas 2001, was named after the rainforest of the eastern slopes of the Andes.
The team will publish detailed reports on what it found in several scientific journals.
Dr Michael Harvey, a tropical biologist at Florida International University, confirmed that the team had made genuinely new discoveries, and said several of the other species appeared to be range extensions or new additions to Bolivia’s fauna.
The project leader, Ross MacLeod, said: “Fifteen per cent of the frog species in this forest are found nowhere else in the world, so these two new frogs are a particularly significant find.
“Many other species are still undescribed in the High Andes, and given the current pace of habitat degradation they may soon become extinct. — Dawn ScienceDotcom Report
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