Killer Asteroid Hunter suffering from Short-Sightedness

The first of the asteroid-hunting Pan-STARRS telescopes will be taken apart today in an effort to solve problems with image quality.

The 1.8-metre PS1 telescope is the first of a suite of instruments – the Panoramic Survey Telescope and Rapid Response System – designed to find asteroids and comets with orbits that could bring them close to Earth.

Sited atop a volcano on the Hawaiian island of Maui, PS1 is the prototype for a planned four telescopes that will image the whole sky visible from Hawaii three times each month.

To scan so much sky, PS1 boasts a 1.4-billion-pixel digital camera and specially designed software to process the terabytes of data collected by the telescope each night.

But since the camera was installed in 2007, the telescope team has been struggling to get PS1's image quality to its targeted level. "There have been problems that we just didn't anticipate," says Pan-STARRS principal investigator Nick Kaiser of the University of Hawaii at Manoa.

Big bananas

PS1's first problem was a misalignment of the optics. "When we switched the telescope on two years ago we had terrible-looking images. We could get sort-of round stars in the middle of the field, but they were big and fuzzy. But the stars at ends of the field looked like telephone handles or big bananas," Kaiser told New Scientist.

That problem was quickly fixed, but the images PS1 is taking are still 40 to 50 per cent fuzzier than they are supposed to be. "We're spending half our time doing mediocre science and half our time trying to improve it so we can do great science," says PS1's director, Ken Chambers, a colleague of Kaiser at Manoa.

The main culprit now seems to be a set of joints connected to the 18 rods that hold up the telescope's secondary mirror. These joints help connect the mirror to motors that adjust the mirror to counteract distortions of the telescope, which expands and contracts due to temperature changes and sags slightly as it scans across the sky.

The minute adjustments of the mirror are not occurring as they should be owing to a flaw in the original design, says Kaiser. So a crew will remove the secondary mirror to replace the joints and make other improvements to the support structure. The telescope is expected to be offline for several weeks, but if all goes well the procedure should go a long way toward improving the telescope's image quality.

One of the Earliest Primitive Maps Found in Spain

"Imagine a group of hunter-gatherers, returning to an area they had not been to for a long time. How do you find a particular cave, especially if the vegetation has changed and its entrance may be masked?" asks independent archaeologist Paul Bahn.

The answer may be that hunter-gatherers had their own maps. A team of archaeologists have matched etchings made 14,000 years ago on a polished chunk of sandstone in northern Spain to the landscape in which it was found. They claim to have the earliest known map of a region in western Europe - a prehistoric hunting map.

The rock, roughly hand-sized and 14,000 years old, bears a mess of overlapping etchings. It was found in a cave in Navarre on the southern side of the Pyrenees and it took Pilar Utrilla of the University of Zaragoza, Spain, and colleagues the better part of 10 years to disentangle the lines and make sense of them (Journal of Human Evolution, DOI: 10.1016/j.jhevol.2009.05.005).

Above recognisable depictions of reindeer, a stag and some ibex are what Utrilla's team believe is a representation of the landscape surrounding the cave. Several etched lines resemble the shapes of mountains that are visible from the cave.

Long, meandering etches match the course of a river that runs at the foot of one of the mountains and splits into two tributaries. A series of strokes that cut across the river near the mountain could represent places where it was easily crossed, or even bridges, the researchers say.

"This is a pretty spectacular find," says prehistoric archaeologist Lawrence Straus of the University of New Mexico in Albuquerque. "It may give us a glimpse into the ways in which people navigated and explained their territories."

He says the slab was etched during a period of enormous cultural activity in northern Spain. "The human range was expanding northward and population density was increasing after people nearly died off in the last glacial maximum about 20,000 to 17,000 years ago.

People were perhaps having to cooperate, carving up territories among different bands. They had to live by their wits and what the landscape provided." Strauss says engravings and paintings would have helped with territorial definition, hunting, human aggregation and mobility, and generally making sense of the world.

Ötzi the iceman: Leaves a Wealth of Knowledge

Ötzi is a mummified human discovered in 1991 in the Schnalstal glacier in the Alps, on the border between Austria and Italy. He died around 3300 BC.

The mummy offers a wealth of information about the humans living in Europe at the time. Ötzi was named after the Ötztal region where he was found.

The new EURAC Iceman photoscan website now gives all web users access to images of the body gathered by researchers. The site has a dynamic online-map-style interface to let people zoom into photographs that capture Ötzi from all angles and show details as small as 1 millimetre.

(Image: © South Tyrol Museum of Archaeology / Eurac / Marco Samadelli / Gregor Staschitz)