Tag Archives: Philae

Defunct Philae found on the surface of the comet

As Rosetta’s mission draws close to an end, its high-resolution camera snapped a few photos of the Philae lander, wedged into a dark crack on Comet 67P/Churyumov–Gerasimenko.

Can you spot Philae in this picture? Zoomed-in version below. Image via ESA.

In August 2014, the Rosetta spacecraft became the first man-made object to interact with a comet from close range. It performed a series of maneuvers which allowed it to enter the comet’s orbit, and from there made several important observations, transmitting a trove of valuable data back to Earth. But the European mission was even more ambitious than this: they sent a lander to the surface of the comet.

The Philae lander detached from Rosetta on 12 November 2014 but things didn’t go as smoothly as possible. The landing was a bit odd, with Philae failing to launch one of its anchoring harpoons. A thruster designed to hold the probe onto the surface also didn’t fire, and the probe bounced off the surface twice. After this, Philae did manage to land on the comet, but it really wasn’t the optimal land we were hoping for.

The land left it in a less-than-ideal position in a shaded area. Its battery ran out of power 3 days later, and because it lacked access to sunlight it couldn’t really power up again. Rosetta’s communications module with the lander was completely turned off on 27 July 2016 and we’ve known nothing of the probe ever since – it was completely silent.

But now, with one month left of the Rosetta mission, the craft spotted Philae again.

“With only a month left of the Rosetta mission, we are so happy to have finally imaged Philae, and to see it in such amazing detail,” says Cecilia Tubiana of the OSIRIS camera team, the first person to see the images when they were downlinked from Rosetta yesterday.

“After months of work, with the focus and the evidence pointing more and more to this lander candidate, I’m very excited and thrilled that we finally have this all-important picture of Philae sitting in Abydos,” says ESA’s Laurence O’Rourke, who has been coordinating the search efforts over the last months at ESA, with the OSIRIS and Lander Science Operations and Navigation Center (SONC, CNES) teams.

The team had been actively searching for Philae for months, but it wasn’t an easy job. At the camera’s resolution of 5 cm/pixel, this was just barely enough to reveal features of Philae’s 1 m-sized body and its legs, as can be seen in this image.

Philae close-up, labelled. The images were taken from a distance of 2.7 km, and have a scale of about 5 cm/pixel. Philae’s 1 m wide body and two of its three legs can be seen extended from the body.

“This remarkable discovery comes at the end of a long, painstaking search,” says Patrick Martin, ESA’s Rosetta Mission Manager. “We were beginning to think that Philae would remain lost forever. It is incredible we have captured this at the final hour.”

“This wonderful news means that we now have the missing ‘ground-truth’ information needed to put Philae’s three days of science into proper context, now that we know where that ground actually is!” says Matt Taylor, ESA’s Rosetta project scientist.

The discovery comes less than a month before Rosetta descends to the comet’s surface. At the end of this month, on 30 September, Rosetta will be sent on a one-way mission to investigate the comet from close up.

 

What comet dust looks like, courtesy of ESA’s Rosetta mission

Millions of miles afar, comets dot the night’s sky leaving an unmistakable trail of dust, gas and ice. In 2014, Rosetta’s Philae probe landed on a comet — a monumental achievement in space exploration — documenting the inner workings, chemical composition and structure of these fascinating cosmic bodies. Among others, we now know the 67P/Churyumov–Gerasimenko comet has sinkholes or holds primordial oxygen. Now, researchers revealed a more familiar curiosity: what dust particles on a comet look like.

Diversity of particles seen on a small area on one single target. This image section measures 2.5 mm across, with light coming from the right. Examples of a compact particle (a), a shattered cluster (b), a glued cluster (c) and a large rubble pile (d) are seen in this small area. Image: ESA

Diversity of particles seen on a small area on one single target. This image section measures 2.5 mm across, with light coming from the right. Examples of a compact particle (a), a shattered cluster (b), a glued cluster (c) and a large rubble pile (d) are seen in this small area. Image: ESA

Dust grains were collected between 1 August 2014 – 3 April 2015 across nine 1 cm^2 targets and analyzed using the COSIMA instrument onboard Rosetta. The team led by Yves Langevin of the Institut d’Astrophysique Spatiale at CNRS/University of Paris-Sud, France, characterized the grains by appearance complexity and particle strength.

These images reveal particles from the comet are very diverse in scales ranging from a few  10s of micrometers (μm) to several 100 μm.  In general, the dust families can be divided into compact particles or clusters, with the cluster group further subdivided into shattered clusters, glued clusters and rubble piles.

Compact particles are defined as those with well-defined boundaries, more-often-than-not found without any related smaller ‘satellite’ particles. Credit: ESA

Compact particles are defined as those with well-defined boundaries, more-often-than-not found without any related smaller ‘satellite’ particles. Credit: ESA

Shattered cluster Estelle, one of the most tightly-packed shattered clusters identified. It has three major components plus many minor components. The right hand image is the 3D anaglyph. Credit: ESA

Shattered cluster Estelle, one of the most tightly-packed shattered clusters identified. It has three major components plus many minor components. The right hand image is the 3D anaglyph. Credit: ESA

Glued clusters comprise relatively well-defined particles with an overall complex structure including sub-components which appear to be linked together by a fine-grained matrix, giving the appearance of a smooth surface texture.  Credit: ESA

Glued clusters comprise relatively well-defined particles with an overall complex structure including sub-components which appear to be linked together by a fine-grained matrix, giving the appearance of a smooth surface texture. Credit: ESA

Reference: Typology of dust particles collected by the COSIMA mass spectrometer in the inner coma of 67P/Churyumov-Gerasimenko” by Y. Langevin et al is published in the journal Icarus.

We have new data from the Philae lander – it identifies several new organic molecules on Comet 67P, charts internal structure

NASA’s Rosetta mission began with what some would call a streak of bad luck.

After the successful separation procedure, Philae’s anchoring harpoons failed to fire and the 220-lb. (100 kilograms) lander bounced off 67P’s surface, clipped a crater rim and then bounced a second time before finally coming to rest nearly two hours after first making contact with the comet’s surface.

Philae’s landing points on Comet 67P/Churyumov-Gerasimenko on Nov. 12, 2014.

The plan was for it to recharge its power supply using photo-voltaic panels, but the place it eventually landed on was quite shady. The stranded probe transmited preliminary data until its primary battery was depleted (about 60 hours), and then went into hibernation.

The initial observations, published on July 30 in the journal Science, show that the comet is a porous body with a fairly homogeneous interior. It also has a diverse surface that harbors many different carbon-containing organic molecules, the scientists said.

“What really blows my mind is to have this combination of complementary results, allowing us at the same time to ‘feel’ the surface of the comet, very locally, as if we were there, while also getting the bigger picture through the sounding of the cometary interior structure,” Nicolas Altobelli, acting Rosetta project scientist, told Space.com via email.

“The implications of these measurements, and in particular the fairly homogeneous, very porous structure of the interior, will help constrain the formation models of planetesimals in the solar nebula, by a better understanding of the accretion processes,” Altobelli added, referring to the process by which planetary bodies, stars, comets and so on are formed from spacedust.

Not elegant but effective

While the landing definitely had scientists on the edge, in the end it seems to have been a boon in disguise, as it allowed observations of different locations on 67P’s body, in its initial and final landing spots (which have been dubbed Agilkia and Abydos, respectively).

And those two sites are quite different, it turns out. Agilkia’s surface is relatively soft, covered with a layer of granular material about 0.82 feet (0.25 meters) deep, while Abydos is much harder.

 

Two trajectory reconstructions of the lander’s touchdown.

“Before the landing of Philae, we believed cometary surfaces might be very soft (loose regolith under low gravity). Some colleagues even feared the lander may sink deeply into the surface at touchdown,” Philae project manager Stephan Ulamec, of the German Aerospace Center (DLR), told Space.com via email. “Although we were aware of our limited knowledge, the fact that some of the material is so hard, and that the surface is so heterogen[eous], was indeed a bit surprising.”

Images captured by Philae’s Comet Infrared and Visible Analyser camera, or CIVA, highlight the diversity and complexity of 67P’s surface, showing fractured, boulder-studded terrain with a variety of grain sizes and reflectivity.

The soft layer of “dirt” goes up to 6.5 feet (2 meters) deep in some places on the surface of the comet, and nonexistent in others, suggest images taken from the ROLIS (Rosetta Lander Imaging System) during the probe’s descent.

The images also show a boulder about 16.5 feet (5 m) wide, which is partly surrounded by a depression resembling a “wind tail,” an erosional feature also seen on our planet, and Mars. Another 17 such structures have since been identified by mission scientists, with lengths ranging from 16.5 feet to 100 feet (5 to 30 m). They are caused by particles abrading the surface of the comet during its travels, like an interstellar sandblasting.

Temperatures also vary on the surface from very uncomfortable to extremely uncomfortable, without the thermal balance offered by a thick atmosphere – daytime temperatures on the comet’s surface in November 2014 ranged from minus 226 degrees Fahrenheit to minus 298 degrees Fahrenheit (minus 143 to minus 183 degrees Celsius). However, as the comet is closer to the sun, those temperatures have probably risen by now but the difference between the dark and lighted side is presumed to be higher.

An organic cocktail

Two different Philae instruments, known as Ptolemy and COSAC (Cometary Sampling and Composition), hunted for organic compounds— the building blocks of life as we know it — on and around Comet 67P.

While the initial data burst received from the lander did hint at the existence of organics on its surface, the data was limited and its meaning not very clear.

The new data is much more interesting. Both instruments detected lots of molecules. COSAC, for example, found 16 different organics, including four (methyl isocyanate, acetone, propionaldehyde, and acetamide) that had never been spotted on or around a comet before.

“If such cometary material falls onto a planet in the right environment, emerging life could make use of it,” COSAC principal investigator Fred Goesmann, of the Max Planck Institute for Solar System Research in Germany, told Space.com via email.

Ptolemy’s observations also revealed a rich mix of organics, along with lots of water and carbon dioxide.

“I think an understanding of the organic compounds that are present in this particular comet will have tremendous ramifications for origin-of-life studies,” Ptolemy principal investigator Ian Wright, of the Open University in the United Kingdom, told Space.com.

The newly reported Ptolemy data were gathered during a calibration run, Wright said, adding that more results from the instrument will be published soon.

Internal structure also charted.

Using its CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) instrument, the Rosetta lander also studied the interior structure of the comet. This instrument picks up long-wavelength signals beamed through 67P by the orbiting Rosetta mothership.

Data suggest that the “head” of the comet is homogeneous -on the scale of a few tens of meters- and really porous, with open space making up 75 to 85 percent of its volume, researchers said.

Observations done with this instrument have also narrowed down the area where the lander might be found -we lost it a little– to a ribbon about 69 feet wide by 112 feet long (21 by 34 m).

“Philae provided us unique information on a comet’s surface properties (and interior) that could not be obtained from orbiter measurements alone,” Ulamec said. “We learned so much about comets that now future missions can be adapted in a much better way to this challenging environment.”

And Philae’s not out yet!

The newly released studies are not necessarily the last word from Philae, as the lander woke from hibernation in mid-June.

Communication between Philae and its handlers here on Earth remains extremely spotty — the last contact occurred on July 9 — but the mission team holds out hope that it can get the lander up and running again soon.

“We keep listening and sending commands to Philae, every time we have an opportunity for communication,” Altobelli said.

 

Life on comets? Not so fast, astronomers say!

Yesterday, we presented an article in which we detailed the claims of two astronomers, Director of the Buckingham Centre for Astrobiology professor Chandra Wickramasinghe and his colleague Dr Max Wallis from the University of Cardiff; they proposed that Rosetta’s lander Philae may have actually landed on an inhabited comet – as the black slime on the surface suggests. However, the rest of the astronomical community has been vocal in contesting these claims.

Image via ESA.

The Rosetta Probe is trailing 67P/Churyumov-Gerasimenko, and the Philae lander has woken up from its slumber on the comet and started transmitting once again. Upon analyzing the images and running some computer simulations, Wallis and Wickramasinghe came to the conclusion that the dark slime on the surface of the comet could be a result of microbial activity – but not everyone agrees (to put it mildly).

“No scientist active in any of the Rosetta instrument science teams assumes the presence of living micro-organisms beneath the cometary surface crust,” Uwe Meierhenrich of Université Nice Sophia Antipolis, France, reportedly told The Guardian in an email exchange on Monday afternoon.

Meierhenrich serves as a co-investigator on Philae’s COSAC instrument, which was designed to chemically analyse the comet. According to him, comet’s black surface crust was predicted all the way back in 1986 by J. Mayo Greenberg (Nature 321, 385), who calculated what would happen to organic, non-living molecules struck by cosmic rays and light.

“These explanations seem to be valid, also with regard to new data of the cometary Rosetta mission,” wrote Meierhenrich.

So not only do we have a perfectly rational explanation that doesn’t involve alien life on a comet, but we have an explanation that was proposed since the 1980s. Several prominent astronomers were vocal and

“I think it is highly unlikely,” Professor Monica Grady of the Open University told the paper. Grady helped design the stunningly sophisticated Ptolemy instrument carried by Philae, Rosetta’s lander.

Furthermore, according to members working on the Rosetta mission, if life were actually present on the comet, we would actually be able to pick it up. COSAC and the PTOLEMY instrument on Philae could measure levels of chemicals associated with living organisms.

“We can thereby well distinguish between the biological and astrochemical formation of organics,” wrote Meierhenrich.

Some scientists were a bit more firm in their statements. Professor Dave Rothery of the Open University posted in a comment on Facebook:

“The Guardian and the RAS disgraced themselves today with the ‘top scientists’ argue case for life on comet’ piece today. I’ve just sat through the talk behind the press release and I think it fair to say that the audience was polite but entirely unconvinced. Diatoms [a type of micro-organism] in comets, my arse!”

 

Philae could be sitting on a comet filled with alien life and not even know it

Comet lander Philae may be sitting on top of microbial life and not even know it – even worse, it has no way of figuring out if it actually is. According to two researchers, the comet’s characteristics (as well as computer simulations) might indicate that the surface may be teeming with microbes.

The black layer on the comet’s surface may be a result of microbial activity, scientists claim.

The Rosetta spacecraft was launched in March 2004 by the European Space Agency (ESA). Along with Philae, its lander module, its main goal was to perform a detailed study of comet 67P/Churyumov–Gerasimenko (67P); this was actually the first mission to orbit and study a comet up close. In late 2014, Philae successfully landed on a comet and obtained detailed images of the comet’s surface. On 15 November 2014, Philae entered its hibernation mode after its batteries ran down due to reduced sunlight, but in June 2015, Philae woke up and started communicating again, sending some important clues regarding potential alien life on the comet.

The comet has a black, organic-rich crust, which could with organisms making their way beneath its icy surface. Of course, there are other (more reasonable) explanations, but researchers seem adamant in their claims. If there is in fact life on comet 67P, then it would be nothing more than microbes, but these microbes would be huge (figuratively, not literally) – it would be mind boggling, which is why so many are skeptical about these claims.

Director of the Buckingham Centre for Astrobiology professor Chandra Wickramasinghe and his colleague Dr Max Wallis from the University of Cardiff have said that comet 67P and others like it may have significant populations of extremophiles on it – organisms that can survive in extreme conditions, like the ones on 67P.

“These are not easily explained in terms of prebiotic chemistry. The dark material is being constantly replenished as it is boiled off by heat from the sun. Something must be doing that at a fairly prolific rate,” Wickramasinghe said.

The comet has a black hydrocarbon crust overlaying ice, smooth icy ‘seas’, and flat-bottomed craters containing ‘lakes’ of re-frozen water overlain with organic debris.

To make things even more tantalizing, Wickramasinghe and Wallis conducted computer simulations which showed that it would be (theoretically) possible for microbes to survive on the comet. The astronomers present their case for life on 67P at the Royal Astronomical Society’s National Astronomy Meeting in Llandudno, Wales. Now, scientists are kicking themselves for not adding life-detection technology to Philae.

“I wanted to include a very inexpensive life-detection experiment. At the time it was thought this was a bizarre proposition,” Wickramasinghe added.

Furthermore, several cracks in the ice had been shown to be ‘spewing out material’ that is falling on to the surface, which also points to microbial activity.

“I think the microbiotic activity just under the surface results in gas which builds up to the point where the overlaying layers of ice can’t withstand the stresses,” said the professor.

If this were actually the case, if life actually exists on comet, it would be huge – potentially force us to rethink what we know about the very emergence of life. It also has vast implications for life on Earth; would life on Earth evolved by itself, or would have it been “seeded” by comets? But as strange and difficult to accept this may be, we have to keep an open mind.

“Five hundred years ago it was a struggle to have people accept that the Earth was not the center of the universe. After that revolution our thinking has remained Earth-centered in relation to life and biology. It’s deeply ingrained in our scientific culture and it will take a lot of evidence to kick it over,” Wickramasinghe said.

 

Rosetta spacecraft finds huge sinkholes on comet’s surface

Rosetta is a robotic space probe built and launched by the European Space Agency. Along with Philae, its lander module, the craft is performing a detailed study of comet 67P/Churyumov–Gerasimenko.

The probe usually orbits 67P at a distance of a few hundred kilometers. Footage received from Rosetta over the last year showed a number of dust jets coming from the comet, which we expected to see. But, after analyzing high-fidelity images from the lander’s OSIRIS instruments, taken just ten to 30 km from the comet’s center, scientists saw that at least some of the dust jets come from specific locations on the comet’s surface, being projected from huge sinkholes.

The scientists have picked out 18 quasi-circular pits in the northern hemisphere of the comet, some of which are still active now. Each sinkhole is anywhere from a few tens of metres to hundreds of metres in diameter and go below the surface by up to 210m to a smooth dust-covered floor.

A catalogue of sinkholes spotted by Rosetta on comet 67P/Churyumov-Gerasimenko.
Image via: forbes.com

“We see jets arising from the fractured areas of the walls inside the pits. These fractures mean that volatiles trapped under the surface can be warmed more easily and subsequently escape into space,” says Jean-Baptiste Vincent from the Max Planck Institute for Solar System Research, lead author of the study.

Similar to the ones on Earth, these sinkholes form when a cavity opens up under the surface. As it widens and deepens, the loss of material makes the ceiling too thin to support its own weight, and collapses. After the collapse, the volatile materials can evaporate or be eroded more easily, and the sinkhole enlarges over time.

“Although we think the collapse that produces a pit is sudden, the cavity in the porous subsurface could have growing over much longer timescales,” says co-author Sebastien Besse, of ESA’s ESTEC technical centre in the Netherlands.

So, what caused these cavities to form in the first place? The team has three theories that they are pursuing.

The first one is that they are artifacts of the comet’s weak gravitational field. When it formed, material accreted by means of low-velocity impacts, leaving behind void areas due to the imperfect fit between primordial building blocks. Over time, seismic events or space impacts cause the surface to weaken enough to cause it to collapse.

Another possibility is that the pits are full of volatile ices like carbon dioxide and carbon monoxide, sitting just beneath a layer of dust. These ices could be melted by the warmth of the Sun as the comet draws closer in its orbit every year.

Or it could be that the ice manages to melt itself away by transforming from amorphous ice made up of irregularly packed molecules to crystallised ice, a process that would release heat which could be sufficient to cause evaporation.

Close-up photo of sinkholes on 67P.
Image via: esa.int

“Regardless of the processes creating the cavities, these features show us that there are large structural and/or compositional differences within the first few hundred metres of the comet’s surface and the cavities are revealing relatively unprocessed materials that might not otherwise be visible,” says Besse.

Researchers analyzing the interior structure of the sinkholes found that their interiors differ quite significantly, with some showing fractured material and terraces, others showing horizontal layers and vertical striations and others also showing globular structures nicknamed “goosebumps”.

“We think that we might be able to use the pits to characterise the relative ages of the comet’s surface: the more pits there are in a region, the younger and less processed the surface there is,” explains Vincent. “This is confirmed by recent observations of the southern hemisphere: this is more highly processed because it receives significantly more energy than the northern hemisphere, and does not seem to display similar pit structures.”

Active pits on Churyumov-Gerasimenko.

Rosetta scientists are hopeful that the spacecraft might yet get to see the formation of a sinkhole in action. The probe did see one outburst during its approach to the comet back in April 2014, which generated between 1,000kg and 100,000kg of material. But although a pit collapse could have been responsible for this, it was much smaller than the researchers expect.

With the collapse of a typical large pit of 140m wide and 140m deep, the team would expect to see the release of around a billion kilograms of material.

“Being able to observe changes in the comet, in particular linking activity to features on the surface, is a key capability of Rosetta and will help us to understand how the comet’s interior and surface have evolved since its formation. And with the extension of the mission until September 2016, we can do the best job possible at unravelling how comets work” says Matt Taylor.

 

 

 

Rosetta to continue its mission and land on a comet

The European Space Agency has confirmed that the Rosetta mission will continue until at least September 2016, when it will most likely land on a comet called Comet 67P.

Comet 67P in September 2014. Image credits: ESA.

Rosetta is a robotic space probe built and launched by the European Space Agency. Along with Philae, its lander module, Rosetta is performing a detailed study of comet Churyumov–Gerasimenko (67P). In August 2014, Rosetta rendezvoused with the comet 67P and sent Philae to land on the comet, from which it gathered some extremely valuable information (such as water not coming from comets).

Now, the mission will be continued, and the probe itself might land on a comet by September next year – if everything goes according to plan.

“This is fantastic news for science,” said Matt Taylor, ESA’s Rosetta Project scientist. “We’ll be able to monitor the decline in the comet’s activity as we move away from the Sun again, and we’ll have the opportunity to fly closer to the comet to continue collecting more unique data. By comparing detailed ‘before and after’ data, we’ll have a much better understanding of how comets evolve during their lifetimes.”

The next comes after Philae woke up from its seven month hibernation which resulted after Philae which landed in an unintended, shadowed area on the surface of a comet in November and couldn’t recharge with solar energy. But on Friday, the lander sent two-minute radio transmissions to Earth, signaling its awakening.

“Among other things, we have received updated status information,” Michael Maibaum, deputy operations manager at the German space agency’s Lander Control Center in Cologne, said in a statement.“ At present, the lander is operating at a temperature of zero degrees Celsius, which means that the battery is now warm enough to store energy. This means that Philae will also be able to work during the comet’s night, regardless of solar illumination,” he said.

Rosetta’s orbit is currently being adjusted so Philae can have an easier time signalling back to Earth, and to prepare for the ultimate landing on the comet it’s been following around for so long.

“This time, as we’re riding along next to the comet, the most logical way to end the mission is to set Rosetta down on the surface,” said Patrick Martin, Rosetta Mission Manager.

Unfortunately though, even if Rosetta manages to land on 67P, it seems unlikely that it may manage to send data from there.

Organic molecules found on comet

As we were telling you already in several articles, the Rosetta probe is in orbit of a comet – the 67P/Churyumov-Gerasimenko comet. But to make things even more exciting, Philae, Rosetta’s lander, also made contact with the comet; among other things, the lander found carbon molecules on the comet – the basis of life on Earth. Considering how comets are believed to have formed during the earlier stages of our solar system, this could also shed light on how life evolved on Earth.

The Philae lander found organic molecules on the surface of a comet.

Though Philae’s adventure on the comet was short lived (lasting only 60 hours), the lander sent home important data. The first important piece of information is that the comet has organic molecules on its surface; not so much has been released about the molecules so far – we only know that they are carbon molecules, not how complex and what type. Other analysis showed that the comet is covered in ice, with only a thin dust layer above.

Dr Fred Goessmann, principal investigator on the Cosac instrument, which made the molecule detection said that the team is still working on interpreting the results, and no additional information will be given until that is solved. This is only natural, because the stake is so high; they may provide crucial insight to 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. Let’s rewind a bit.

We still don’t know how life appeared on our planet. The earliest evidence for life on Earth comes from fossilized mats of cyanobacteria called stromatolites in Australia that are about 3.4 billion years old. There may have been other, earlier life forms, but they haven’t left any signs of their existence – or at least we haven’t found them. Still, the general idea is that life appeared sometime during that period. But even as scientists have a fairly good idea when life appeared, we still don’t know how it appeared.

“Many theories of the origin of life have been proposed, but since it’s hard to prove or disprove them, no fully accepted theory exists,” said Diana Northup, a cave biologist at the University of New Mexico.

Among the leading theories, there is the idea that crucial organic molecules came from outer space, through comets. Complex organic compounds, like amino acids, are the building blocks to life. The conditions on the young Earth were not favorable for making those compounds, and for this reason, many researchers believe they came from an outside source.

The discovery of the molecules was made with Philae’s Cometary Sampling and Composition Experiment (COSAC) instrument. Philae also inspected the ice on the surface of the comet. Because the temperature is so low, the ice has the tensile strength of a sandstone on Earth.

“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 BBC News. People will be playing with [mathematical] models of pure water-ice mixed with certain amount of dust.”

There is still some doubt regarding the nature of the ice, but researchers are pretty certain.

“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.”

Unfortunately, we can’t get a full picture yet. Scientists had to conduct as many analysis as possible before Philae’s battery ran out, but they weren’t able to conduct all the tests they planned.

“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.”

But Philae is not gone for good yet – as the comet closes in on the sun, it will also recharge its batteries – unfortunately, this will also bring its demise.

 

Rosetta’s Philae probe landed on a comet – why this is HUGE news

OK, so we’ve been keeping you up to date with what’s been happening with the Rosetta mission, but we had to sleep eventually, and wonderful things have happened in the mean time. In case you’re not aware, here’s a short summary: Rosetta is a probe launched by the European Space Agency (the European equivalent of NASA) in order to study a comet. Rosetta has been orbiting the comet for a while, took some breathtaking pictures, and eventually sent a lander towards the probe. There have been some technical issues, but in a stunning achievement, Philae, the lander, managed to attach itself to the comet! Here’s why this is a big deal.


First image from the surface of Comet 67P/Churyumov-Gerasimenko from the Rosetta million’s lander Philae Photograph: ESA/Rosetta/Philae/CIVA/Photograph: ESA/Rosetta/Philae/CIVA

First of all, the technical achievement is spectacular. It’s the first time humans have landed anything on a comet. Comets have negligible gravity so it’s hard to establish an orbit around comets. Also, landing there is difficult because there’s a risk of the lander simply bouncing off the surface of the comet. Comets are also very mobile, with often irregular orbits, bringing even more problems to the table.

Comets are icy remnants which took shape in the initial phases of the solar system. Studying the composition of comets might yield important information about the birth of the solar system. Also, many researchers believe that comets are the initial source of water on our planet. While it is possible that some water was released from the Earth’s interior at this time, comets are a likely source of initial water. The mission could confirm or infirm this theory.

Photo credit: Matt Wang, Flickr: anosmicovni. European Space Agency. Comet 67P/Churyumov–Gerasimenko Relative to Downtown Los Angeles

Rosetta has a wide array of machines onboard, including spectrographs, mass-spectrometers, microscopes and plasma sensors. But there is only so much information which can be gathered without actually landing on the comet – an this is where Philae enters the scene.

After successfully detaching itself from Rosetta, Philae spent 7 hours gracefully dancing its way towards the surface of the comet. Not everything went smoothly at the land, as Lander project manager Stephan Ulamec has told the BBC’s Jonathan Amos:

“We are still not anchored. We are sitting with the weight of the lander somehow on the comet. We are pretty sure where we landed the first time, and then we made quite a leap. Some people say it is in the order of 1 km high. And then we had another small leap, and now we are sitting there, and transmitting, and everything else is something we have to start understanding and keep interpreting.”

Assuming success, a scientific trove awaits; the comet has already surprised researchers several times, and there is no telling what other things we will find about our solar system. Some experiments are already underway, as scientists from the Open University explain:

The first experiment, CIVA-P, consists of seven identical cameras that will produce a panoramic image of the comet as seen from Philae. CIVA-P will characterise the landing site, mapping the surface topography and the albedo (reflectivity) of the surface. Two of the camera are aligned so as to produce stereoscopic images.

The mission is even more laudable thanks to its efficiency – it cost European citizens a mere 3.5 euro to conduct this mission – even less than a cinema ticket.

 

Rosetta comet landing – watch it as it happens! [live blog]

In case you’re not aware, the European Space Agency is just now trying to send Rosetta’s lander, Philae, towards the comet 67P/Churyumov–Gerasimenko. The probe is already orbiting the comet and has revealed the most accurate topography of a comet. Watch the live stream here:

Further updates: The separation went great, and the lander is on its way to the comet.

09:06 GMT. Philae is now on its way to the Rosetta comet, everybody is glad that it worked flawlessly. There are still many more crucial moments (the most important one a few hours from now), but so far, everything is just fine.

09:04 GMT. Success! The separation appears to have been successful.

09:00 GMT. We are just moments away from finding out if the separation was successful!

08:59 GMT.Rosetta’s trajectory:

After it has deployed Philae, it will manoeuvre away to keep Philae and the landing site in view. Illustration: Esa

08:44 GMT. The separation has already taken place… hopefully. However, there’s no way for us to know until the signal reaches Earth. At t he moment, several astronomers are discussing the project on the stream.

08:39 GMT. In case you would like to send comments or questions to the people working at the ESA, use: #cometlanding.

The Rosetta is currently working on its ‘pre-separation manoeuvre’. This is a thruster burn to place it on course for the separation point, when it will release Philae. There are, however, significant problems. The cold gas thruster seems to not work properly, and without the thruster, the risk of Philae bouncing off the surface of the comet has increased. However, all other devices are working properly, so the team decided to go ahead and rely on three screws and two harpoons to drill the legs to the surface of the comet.

08:34 GMT. Overnight, there have been two more go/nogo decisions. Both were ‘go’ but the Philae lander team needed an additional hour before they confirmed that they were indeed ‘good to go’. Right now, we are at a point of no going back, and as I am writing this, we will see the separation about 30 minutes from now. Well, actually, it is happening NOW, but because the distance between Earth and the comet is so large, it will take the signal almost 30 minutes to reach Earth.

08:20 GMT. It’s a very risky mission, landing something on a comet. It’s the first time something like this has been attempted.

 

Artistic depiction of Philae landing on the comet. Image credits: ESA.

Professor Ian Wright at The Open University is the Principal Investigator for the Ptolemy instrument on board the Rosetta mission. He is in Darmstadt at the moment. You can watch a video of Wright answering questions about the Rosetta mission here: