Just when the world is abuzz about the possibility that the Mars Phoenix Lander will find evidence of liquid water and life-enabling conditions in the prehistoric Martian past, a new report throws a bucket of salty water on that enthusiasm.

Researchers studied geochemical findings from the Mars rover Opportunity, and now say that even if liquid water did exist on Mars in a warmer era in the planet’s history, it was probably too salty to support life — or at least, life as we know it.

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A clump of hair that lay frozen in the Greenland tundra for 4,000 years has yielded DNA from the earliest Arctic residents, and offers clues to their origins.

Researchers have long wondered who those rugged settlers were, and where they came from. Were they part of a massive migration that swept through all of North America, or were they a separate tribe that eventually gave rise to Greenland’s present-day Eskimos?

Until now, no ancient human remains had been found in that harsh climate to allow researchers to study the genetics of those “Paleo-Eskimos.” But the new discovery sheds some light on the people, and suggests that neither of the earlier theories is correct; in fact, they were a distinct tribe that journeyed all the way from Siberia to Greenland, but didn’t stick around to populate the frozen north.

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The Earth was an inhospitable place 635 million years ago, with ice sheets that extended to the equator. Scientists have long wondered how the planet rebounded from that icy era, known as “Snowball Earth.”

Now a new study suggests that a stream of methane gas escaping from the ice brought the planet to a climate tipping point and transformed it into a lush, tropical world, in what researchers called one of the most severe climate change events recorded in Earth history [Nature, subscription required].

Paleoclimatology has become a hot field, as researchers believe that the planet’s dramatic prehistoric climate shifts can help predict the effects of present-day global warming. Since methane figures into one of the most ominous global warming scenarios, this latest study is being eagerly scrutinized for clues to our planet’s fate.

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This can only lead to a summer blockbuster. Researchers implanted tiny electrodes in two monkeys’ brains, allowing them to move robotic arms with their thoughts.

To motivate the monkeys to perform, they were encouraged to feed themselves marshmallows and pieces of fruit with the robotic arms, which had joints and “grippers” that roughly replicated fingers. According to the research team’s report in Nature [subscription required], the arms’ movements were fluid and natural, and the monkeys continuously adjusted the speed and direction of their robotic limbs.

While the technology isn’t yet ready for human testing, scientists are hopeful that it can eventually be applied to prosthetic limbs for people with spinal cord injuries, strokes, and other paralyzing conditions.

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The giant azhdarchid pterosaurs have fascinated paleontologists since their fossils were first discovered in the 1970s. The largest flying animals ever to grace the planet seemed ripped from science fiction: They were taller than giraffes and had wingspans of over 30 feet.

Researchers first believed that these pterosaurs, or “winged lizards,” were scavengers that picked apart carcasses. More recently, paleontologists marveled at the idea of the lizards swooping over coastal waters to hunt like enormous seabirds. Now, after a comprehensive study of the azhdarchids’ footprints and fossils, several researchers have announced their theory that the largest pterosaurs stalked their prey on land like storks, and fed on baby dinosaurs.

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If the shuttle Discovery blasts off as planned this Saturday, it will deliver a $1 billion science lab to the International Space Station, where astronauts will be able to use furnaces to grow crystals and bio-chambers to grow cells.

But the space lab isn’t the shuttle‘s only precious cargo. It will also carry spare parts to allow astronauts to fix their malfunctioning space toilet.

News of the broken space toilet has captivated the earth-bound masses, as people imagine, with horror, being confronted with a balky toilet in a zero gravity environment. NASA has admitted that the toilet broke last Wednesday, when the fan-and-vacuum system that sucks away liquid waste stopped working.

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Finally, the U.S. Department of Defense is working on a bomb that even peaceniks can get behind — a bug bomb!

Motivated by the need to protect soldiers in the field from biting pests, the Defense Department teamed up with the Department of Agriculture to search for a longer-lasting and more effective insect repellent. “That was the principal motivation, the usability for the military,” says USDA investigator Ulrich Bernier. “You don’t want your soldiers reapplying every 15 to 20 minutes” [Science News].

Researchers have already identified several chemical compounds that seem far more effective than the current standard-bearer, DEET. In one test, a cloth soaked with a particularly promising compound repelled mosquitoes for 73 days, while DEET-soaked cloth lasted only 13 days.

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Two days after a flawless touchdown on the surface of Mars, the Phoenix Lander is busily snapping pictures of itself and of the polar landscape.

It landed in an arctic plain near the north pole called Vastitas Borealis, where it is expected to discover water ice mixed in with the frozen soil. In accordance with NASA’s mandate to “follow the water,” its mission is to search for evidence that liquid water may have once flowed on Mars, and to investigate whether conditions may have ever allowed for primitive biological life.

Before the Phoenix’s landing, NASA scientists nervously pointed out that only 55 percent of all attempts to land a vehicle on the Martian surface have been successful; they also noted the spacecraft that the Phoenix most resembles, the Mars Polar Lander, crashed in 1999. However, the Phoenix made it down with only one slight hitch.

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