A robotic submarine designed to explore the oceans thought to lie beneath the icy crust on Jupiter’s moon Europa will prove its mettle in an Antarctic lake in 2008. A previous version of the vessel has already mapped the balmier waters of a Mexican sinkhole.

The submarine, named Endurance, is set to survey Antarctica’s West Lake Bonney in October 2008 and again in 2009, scientists reported on Thursday at a meeting of the American Geophysical Union in San Francisco, California, US. The 4-kilometre-wide lake is 40 metres deep and is capped by a perennial layer of ice about 4 metres thick. The crust has kept the lake’s waters pristine and virtually unexplored.

Hot water drills will bore a hole for Endurance to enter the water. Once beneath the ice, the sub will gather data for a 3D map of the lake and the submerged face of its adjacent glacier. At the same time, it will sample the frigid waters for signs of life.

West Lake Bonney should prove a rigorous test of the submersible’s ability to function on Europa. Once released, Endurance will navigate on its own for up to eight hours at a time – a crucial requirement, since sending radio commands to the distant, icy moon from Earth would take about half an hour.

“Europa’s far enough away where you’re not going to be able to drive it like a video game,” says lead investigator Peter Doran of the University of Illinois in Chicago, US. “The robot would need a fair amount of its own intelligence to make its own decisions. With Endurance, we’re at that point.”

At the lake, Endurance will follow a pre-programmed path just beneath the ice. “This is so we don’t disturb the environment we’re studying with the robot’s propellers,” Doran says.

Instead, the sub will stop and lower a package of scientific instruments into the water column. These will measure water temperature, salinity, turbidity, dissolved organic carbon, and scan for chlorophyll. Together, these measurements should be enough to detect the presence of life.

Docking station

And life may not be so unlikely on Europa. Data from NASA’s Galileo spacecraft has revealed hints of carbon – a building block of life – in the moon’s purported seas. Both carbon dioxide and sulphur dioxide, a potential signal of volcanism, are leaking from discrete areas on the moon’s surface.

Operating a spacecraft at Europa may also be easier than originally thought because radiation on the moon is low enough to operate a probe there for a year or more, says William McKinnon of Washington University in St Louis, Missouri, US.

Still, many hurdles remain before an underwater vehicle will get to tackle otherworldly seas. At present, Endurance is too massive to send on interplanetary travel. Scientists must also devise a means to drill through Europa’s icy crust and lower the sub safely through the ice.

And because radio waves travel poorly through water, a docking station anchored in or around the ice will need to relay data from the submersible to Earth. No one has even begun working on such a transmitter, not least because they need a better understanding of Europa’s ice crust first.

According to McKinnon, an orbiter mission to Europa would need to pave the way before any submersible left the launch pad. Using radar, such a spacecraft could measure ice depth, look for convection cells, and perhaps even detect plumes of volcanic activity in addition to demonstrating the presence of liquid water.

NASA has committed to launching a mission to one of the icy moons of Jupiter or Saturn sometime between 2015 and 2020. The target of that mission, however, is still being decided. According to Curt Niebur of NASA, the space agency has just completed studies of missions to Jupiter’s moons Europa and Ganymede and Saturn’s moons Titan and Enceladus. NASA plans to announce which missions have been selected for further study in mid-January 2008.

Astrobiology – Learn more in our out-of-this-world .

US astronaut Lisa Nowak’s fall from grace – she is accused of trying to kidnap and kill a woman she considered a rival for the affections of a fellow astronaut – has raised a plethora of unanswered questions from a shocked public. Chief among them: how someone who passed the stringent psychological screening required to become an astronaut could have snapped like this.

But scientists aren’t nearly as shocked as the general public. “It doesn’t surprise me that this might happen occasionally,” says psychiatrist Nick Kanas of the University of California in San Francisco, US, who studies astronaut behaviour on long-term space flights. NASA takes medical histories to screen for psychiatric problems that tend to run in families, such as bipolar disorder and schizophrenia. But no battery of tests will reveal how well astronauts will cope with the ups and downs of daily life.

“Astronauts are very capable people, among the stars of our society. But they have changes in their lives, have issues with their spouses and kids just like you and I might,” Kanas says. “They might be superhuman in their jobs, but not in terms of relationships and their potential for emotional problems.”

‘Out of character’

Indeed, Nowak and her husband of 19 years separated a few weeks ago, according to a statement released by her family. The statement added, “These alleged events are completely out of character and have come as a tremendous shock to our family”.

Ironically, some of the qualities and requirements to produce a capable astronaut may have played some role in stoking Nowak’s obsession. Space training can require astronauts to be away from home and loved ones for many months at a time. The exercises often throw astronauts together in extreme conditions to test their performance under stress. Though they never flew together on a mission, records show Nowak and Oefelein they did attend the same survival training session in Canada in 2004.

Most astronauts are relatively young and in excellent physical health, putting them in a demographic that is unusually sexually active. In addition, most have higher than average levels of education. “That often translates into higher levels of sexual activity and adventurousness,” says Ray Noonan, a professor of human sexuality affiliated with the State University of New York, US. Nowak holds a bachelor of science degree in aerospace engineering and a master’s degree in aeronautic engineering (see US astronaut Lisa Nowak: a short biography).

‘All professionals’

The issue of sex among astronauts could become especially important on long-duration space missions, such as those planned for Mars. Researchers say it might provide a sense of normalcy in the isolated and confined environment of a space mission, but they also worry that jealousy or resentment could endanger the mission if the relationship went sour (see Out-of-this-world sex could jeopardise missions).

When asked her opinion on the matter in 1998, Nowak told Reuters that men and women could refrain from romantic relationships because the excitement of setting foot on Mars would prevail over earthly desires. “We’re all professionals,” she said.

The pressure of living up to the squeaky-clean image of an astronaut is also intense. That was particularly difficult in the early days of the space programme, when every astronaut was an instant celebrity. The spotlight harmed more than a few in its glare. Among them was Buzz Aldrin, who suffered through depression, alcoholism and a divorce after becoming the second man to set foot on the Moon.

That spotlight has cooled as spaceflight has become more commonplace. Yet the pressure on astronauts to be upstanding role models remains sky-high.

“This is a highly motivated group of people, so I don’t think it’s unusual to expect that they would want to conform to the role model image for the most part,” Noonan says. “Then again, when you have extreme situations, some people will crack, and we don’t always know sometimes who that will be.”