Northern lights observed on Mars

A Nasa spacecraft orbiting the Red Planet has detected a mysterious aurora that reaches deep into the Martian atmosphere. The Maven mission observed these “Christmas lights” for five days leading up to December 25 last year.

Scientists have also discovered a dust cloud at high altitude, which does not match predictions. The preliminary results were presented at the 46th Lunar and Planetary Science Conference (LPSC) in Texas. The mission was designed to help solve the mystery of how the Red Planet lost most of its atmosphere and much of its water and other volatiles.

“The question is how much water has been lost into the crust, how much has been lost to space. How much CO2 has been lost to the crust, how much to space,” said Maven’s chief scientist Professor Bruce Jakosky from the University of Colorado in Boulder. The bright ultraviolet auroral glow seen by Maven in December spanned Mars’ northern hemisphere.

Auroras, known on Earth as northern or southern lights, are caused by energetic particles such as electrons cascading into the atmosphere and causing the gas to glow. Although Martian auroras have been seen before by Europe’s Mars Express spacecraft, what surprised scientists was how deep in the atmosphere this occurred – much deeper than at Earth or elsewhere on Mars.

But the finding makes a degree of sense because while Earth retains a global protective magnetic field, Mars lost its one billions of years ago. This means that the high energy particles streaming in from the sun make direct strikes, penetrating deep into the atmosphere. Maven also found dust surrounding Mars at altitudes of between 150 km to 300 km up.

“This one was unexpected,” said Prof Bruce . Possible sources for the observed dust include material wafted up from the atmosphere; dust coming from Phobos and Deimos, the two moons of Mars; dust moving in the solar wind away from the sun; or debris orbiting the sun from comets.

But how exactly the dust gets there is still unknown. “If the dust originates from the atmosphere, this suggests we are missing some fundamental process,” said mission scientist Laila Andersson.

Paul Rincon

A navigation system for the blind
Blind rats with a sensor and compass attached to their brains were able to navigate a maze as successfully as sighted rats, researchers found. Researchers at the University of Tokyo wanted to test whether a mammal could use allocentric sense – the awareness of one’s body relative to its environment – to replace vision. The scientists attached a geomagnetic sensor and digital compass to the visual cortices of rats with their eyes sewn shut.

When the rats moved their heads, the sensors generated electrical impulses to tell them which direction they were facing. The rats were then trained to find pellets in various mazes.

Within a few days, the blind rats were able to navigate the mazes as well as rats that could see. The two groups of rodents relied on similar navigation strategies. The findings, published in the journal Current Biology, could help lead to devices that help blind people independently navigate their surroundings.

“The most plausible application is to attach a geomagnetic sensor to a cane so that the blind can know the direction via tactile signals such as vibration,” Yuji Ikegaya, a pharmacologist and co-author of the study, wrote in an e-mail.

Whether the experiment would work as well with rats that were truly blind is not yet known, Yuji added. Such rats might “need a longer time to learn the meaning of geomagnetic information,” he said. Still, he said he believed they would be able to do it.
Douglas Quenqua
NYT