ESA Rosetta mission: Philae instruments detect Organic molecules

The ESA Rosetta Philae lander has detected organic molecules on the surface of its comet, scientists have confirmed.

Carbon-containing "organics" are the basis of life on Earth and may give clues to chemical ingredients delivered to our planet early in its history.

The compounds were picked up by the German-built COSAC instrument designed to "sniff" the comet's thin atmosphere.

Other analyses suggest the comet's surface is largely water-ice covered with a thin dust layer.

The European Space Agency (ESA) craft touched down on the Comet 67P on 12 November after a 10-year journey.

Dr Fred Goessmann, principal investigator on the Cosac instrument, which made the organics detection, confirmed the find to reporters, but he added that the team was still trying to interpret the results.

It has not been disclosed which molecules have been found, or how complex they are.

But the results are likely to provide insights into the possible role of comets in contributing some of the chemical building blocks to the primordial mix from which life evolved on the early Earth.

Preliminary results from the MUPUS instrument, which deployed a hammer to the comet after Philae's landing, suggest there is a layer of dust 10-20cm thick on the surface with very hard water-ice underneath.

The ice would be frozen solid at temperatures encountered in the outer Solar System, MUPUS data suggest this layer has a tensile strength similar to sandstone.

"It's within a very broad spectrum of ice models. It was harder than expected at that location, but it's still within bounds," said Prof Mark McCaughrean, senior science adviser to ESA, told reporters.

"People will be playing with [mathematical] models of pure water-ice mixed with certain amount of dust."

He explained: "You can't rule out rock, but if you look at the global story, we know the overall density of the comet is 0.4g/cubic cm. There's no way the thing's made of rock.

"It's more likely there's sintered ice at the surface with more porous material lower down that hasn't been exposed to the Sun in the same way."

After bouncing off the surface at least twice, Philae came to a stop in some sort of high-walled trap.

"The fact that we landed up against something may actually be in our favour. If we'd landed on the main surface, the dust layer may have been even thicker and it's possible we might not have gone down [to the ice]," said Prof McCaughrean.

Scientists had to race to perform as many key tests as they could before Philae's battery life ran out at the weekend.

On re-charge

A key objective was to drill a sample of "soil" and analyse it in COSAC's oven, but, disappointingly, the latest information suggest no soil was delivered to the instrument.

Prof McCaughrean explained: "We didn't necessarily see many organics in the signal. That could be because we didn't manage to pick up a sample, but what we know is that the drill went down to its full extent and came back up again."

"But there's no independent way to say: This is what the sample looks like before you put it in there."

Scientists are hopeful however that as Comet 67P/Churyumov-Gerasimenko approaches the Sun in coming months, Philae's solar panels will see sunlight again.

This might allow the batteries to re-charge, and enable the lander to perform science once more.

"There's a trade off - once it gets too hot, Philae will die as well. There is a sweet spot," said Prof McCaughrean.

He added: "Given the fact that there is a factor of six, seven, eight in solar illumination and the last action we took was to rotate the body of Philae around to get the bigger solar panel in, I think it's perfectly reasonable to think it may well happen.

"By being in the shadow of the cliff, it might even help us, that we might not get so hot, even at full solar illumination, but if you don't get so hot that you don't overheat, have you got enough solar power to charge the system."

The lander's Alpha Particle X-ray Spectrometer (APXS), designed to provide information on the elemental composition of the surface, seems to have partially seen a signal from its own lens cover - which could have dropped off at a strange angle because Philae was not lying flat.

Organic molecules in Titan's atmosphere are intriguingly skewed

An ALMA image of the distribution of the organic molecule HNC in the upper atmosphere of Saturn's moon Titan. 

The denser, brighter concentrations are shown near the moon's north and south poles. 

Their shifted, off-axis locations were unexpected and could help researchers better understand Titan's complex atmospheric processes. 

The globe outline represents Titan's orientation at the time of the observations. 

Credit: NRAO/AUI/NSF; M. Cordiner et al./NASA

While studying the atmosphere on Saturn's moon Titan, scientists discovered intriguing zones of organic molecules unexpectedly shifted away from its north and south poles.

These misaligned features seem to defy conventional thinking about Titan's windy atmosphere, which should quickly smear out such off-axis concentrations.

"This is an unexpected and potentially groundbreaking discovery," said Martin Cordiner, an astrochemist working at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and the lead author of a study published online today in the Astrophysical Journal Letters.

"These kinds of east-to-west variations have never been seen before in Titan's atmospheric gases. Explaining their origin presents us with a fascinating new problem."

This discovery, made during a remarkably brief three-minute "snapshot" observation with the Atacama Large Millimeter/submillimeter Array (ALMA), may help astronomers better understand the processes that shape this world's complex chemistry.

Titan's atmosphere has long been of interest because it acts as a chemical factory, using energy from the Sun and Saturn's magnetic field to produce a wide range of organic molecules.

Studying this complex chemistry may provide insights into the properties of Earth's very early atmosphere, which may have shared many chemical characteristics with present-day Titan.

An ALMA image of the distribution of the organic molecule HC3N in the upper atmosphere of Saturn's moon Titan. 

The denser, brighter concentrations are shown near the moon's north and south poles. 

Their shifted, off-axis locations were unexpected and could help researchers better understand Titan's complex atmospheric processes. 

The globe outline represents Titan's orientation at the time of the observations. 

Credit: NRAO/AUI/NSF; M. Cordiner et al./NASA

The researchers used ALMA's extreme sensitivity and resolution to track the atmospheric distributions of hydrogen isocyanide (HNC) and cyanoacetylene (HC3N), which initially appeared to be concentrated evenly over Titan's north and south poles.

These findings were consistent with observations made by NASA's Cassini spacecraft, which found high concentrations of some gases over whichever pole is experiencing winter on Titan.


Recent observations of comet Lemmon provided a 3-D view of the inner coma, including detailed mapping of the molecule HCN (made of one hydrogen, one carbon and one nitrogen), shown here, as well as HNC and formaldehyde.

Visualization by Brian R. Kent/NRAOThe surprise came when the research

ers compared the gas concentrations at different levels in the atmosphere. At the highest altitudes, the pockets of organic molecules were shifted away from the poles.

These off-pole concentrations are unexpected because the fast-moving, east-west winds in Titan's middle atmosphere should thoroughly mix the molecules formed there.

The researchers do not have an obvious explanation for these findings yet.

"It seems incredible that chemical mechanisms could be operating on rapid enough timescales to cause enhanced 'pockets' in the observed molecules," said Conor Nixon, a planetary scientist at Goddard and a coauthor of the paper.

"We would expect the molecules to be quickly mixed around the globe by Titan's winds."

An ALMA image of the distribution of the organic molecule HC3N at intermediate-to-lower elevations in the atmosphere of Saturn's moon Titan. 

The denser, brighter concentrations are oriented more evenly about the poles than is observed for HC3N at higher elevations. 

The globe outline represents Titan's orientation at the time of the observations. 

Credit: NRAO/AUI/NSF; M. Cordiner (NASA) et al.

At the moment, the scientists are considering thermal or other effects tied to interaction with Saturn's powerful magnetic field, which extends far enough to engulf Titan, as potential sources of this skewed molecular concentration.

"Alternatively, I don't think we could rule out some kind of peculiar atmospheric circulation pattern," speculates Cordiner.

This marks ALMA's first foray into atmospheric studies of a major body in our Solar System.

Further observations are expected to improve our understanding of the atmosphere and ongoing processes on Titan and other objects throughout our Solar System.

Titan is in some ways the most Earthlike body in the Solar System, with a thick atmosphere and prominent lakes, rivers, and seas.

In place of water, however, Titan's frigid surface flows with liquid organic molecules, including methane (CH4) and ethane (C2H6).

"These ALMA observations give us new insights into how organic molecules, the building blocks of life, form and evolve in a planet-like environment," said Anthony Remijan, an astronomer at the National Radio Astronomy Observatory in Charlottesville, Va., and coauthor on the paper.

"It is exciting to imagine the new discoveries ALMA will enable as we look more deeply at other interesting objects in our Solar System."