ESA Rosetta mission: Philae Lander has difficulty hanging on to comet 67/P

It was a day when science fiction became science fact. With minute-perfect accuracy, scientists landed a probe on a comet following a ten year journey through the solar system.

The European Space Agency predicted that the first signal would arrive back on Earth at 4.03pm confirming that the Philae lander had touched down after being detached from its mother ship Rosetta.

And at 4.03pm the instruments at control centre in Darmstadt, Germany, sparked into life as the probe made contact and furrowed brows were replaced with beaming smiles and tears.

“We are on the comet!” announced Dr Stephan Ulamec, Philae’s Lander Manager. “We are sitting on the surface and Philae is talking to us.”

However initial jubilation was followed by some anxiety after it emerged that the landing harpoons had not activated, meaning that the probe was simply sitting on the soft surface without being securely attached.

Just hours later Dr Ulamec was forced to admit that the scientists had lost contact with the probe and did not actually know where it was.

"It's complicated to land on a comet. It's also complicated to understand what has happened during the landing. What we know is that we touched down and we landed on the comet. We had a very clear signal and we also received data from the lander. That is the very good news

"The not so good news is that the anchoring harpoons did not fire. So the lander is not anchored to the surface. Did we just land in a soft-sand box and everything is fine? Or is there something else happening. We still do not fully understand what has happened.

"Some of the data indicated that the lander may have lifted off again. It touched down and was rebouncing. So maybe today, we didn't just land once, we landed twice."

Scientists had already spent a nerve-racking 24 hours prior to the landing trying to work out why Philae would not power up after its 10 year slumber in space.

They also quickly realised that the thruster jets, designed to help the comet stay on the surface before the landing anchors are deployed, were not working at all. Without the thrusters it was feared the probe would simply bounce off the surface and back into space.

Despite the concerns, they decided to go ahead with the detachment at 8.35am on Wednesday morning. The probe made a perfect seven hour descent onto the comet 67P/Churyumov-Gerasimenko.

But on Wednesday evening scientists were facing the agonising decision of whether to attempt to activate the anchors again and risk pushing the craft back into space, or leave the probe untethered.

“Our big concern is at the moment is whether we are standing stably. We are considering if we need to retry shooting the anchors. said a spokesman for the Philae lander in Cologne.

Yet the science community was in firm agreement that the £1.3 billion mission had been an incredible success and a huge leap forward for astrophysics.

“It is a milestone for space exploration,” said Prof Tom Marsh of the University of Warwick’s Astronomy and Astrophysics group.

“An incredibly difficult task successfully accomplished at a distance of 520 million miles. It does not get much better than this.

“To think that we have landed on an object often thought in the past to be harbingers of doom is remarkable to me. I am looking forward to what we will now learn from Philae. A truly fabulous achievement.”

AUTISM: Difficulty in Recognising Faces Linked to Performance in a Group of Neurons

Neuroscientists at Georgetown University Medical Center (GUMC) have discovered a brain anomaly that explains why some people diagnosed with autism cannot easily recognize faces -- a deficit linked to the impairments in social interactions considered to be the hallmark of the disorder.

They also say that the novel neuroimaging analysis technique they developed to arrive at this finding is likely to help link behavioral deficits to differences at the neural level in a range of neurological disorders.

The final manuscript published March 15 in the online journal NeuroImage: Clinical, the scientists say that in the brains of many individuals with autism, neurons in the brain area that processes faces (the fusiform face area, or FFA) are too broadly "tuned" to finely discriminate between facial features of different people.

They made this discovery using a form of functional magnetic resonance imaging (fMRI) that scans output from the blueberry-sized FFA, located behind the right ear.

"When your brain is processing faces, you want neurons to respond selectively so that each is picking up a different aspect of individual faces. The neurons need to be finely tuned to understand what is dissimilar from one face to another," says the study's senior investigator, Maximilian Riesenhuber, PhD., an associate professor of neuroscience at GUMC.

"What we found in our 15 adult participants with autism is that in those with more severe behavioral deficits, the neurons are more broadly tuned, so that one face looks more like another, as compared with the fine tuning seen in the FFA of typical adults," he says.

"And we found evidence that reduced selectivity in FFA neurons corresponded to greater behavioral deficits in everyday face recognition in our participants. This makes sense. If your neurons cannot tell different faces apart, it makes it more difficult to tell who is talking to you or understand the facial expressions that are conveyed, which limits social interaction."

Riesenhuber adds that there is huge variation in the ability of individuals diagnosed with autism to discriminate faces, and that some autistic people have no problem with facial recognition.

"But for those that do have this challenge, it can have substantial ramifications -- some researchers believe deficits in face processing are at the root of social dysfunction in autism," he says.

The neural basis for face processing
Neuroscientists have used traditional fMRI studies in the past to probe the neural bases of behavioral differences in people with autism, but these studies have produced conflicting results, says Riesenhuber.

"The fundamental problem with traditional fMRI techniques is that they can tell which parts of the brain become active during face processing, but they are poor at directly measuring neuronal selectivity," he says, "and it is this neuronal selectivity that predicts face processing performance, as shown in our previous studies."

To test their hypothesis that differences in neuronal selectivity in the FFA are foundational to differences in face processing abilities in autism, Riesenhuber and the study's lead author, neuroscientist Xiong Jiang, PhD, developed a novel brain imaging analysis technique, termed local regional heterogeneity, to estimate neuronal selectivity.

Read the full article here