Rotten eggs, horse pee, alcohol and bitter almonds: this is the bouquet of odours you would smell if a comet in deep space could be brought back to Earth, European scientists said Rotten eggs, horse pee, alcohol and bitter almonds: this is the bouquet of odours you would smell if a comet in deep space could be brought back to Earth, European scientists said on Thursday. 
 
 An instrument aboard the probe Rosetta has detected some intriguing chemical signatures from Comet 67P/Churyumov-Gerasimenko since their rendezvous in deep space in August, they said. 
 
 Molecules include ammonia, methane, hydrogen sulphide, hydrogen cyanide and formaldehyde. 
 
 "If you could smell the comet, you probably wish that you hadn't," the team said wryly in a blog posted on the European Space Agency (ESA) website. 
 
 The device, called Rosina-DFMS, is a mass spectrometer—it has been analysing the signature of gas given off by the "coma," the comet's head, as the distance closes with the Sun. 
 
 "The perfume of 67P/C-G is quite strong, with the odour of rotten eggs (hydrogen sulphide), horse stable (ammonia) and the pungent, suffocating odour of formaldehyde," said Kathrin Altwegg, Rosina's chief scientist. 
 
 "This is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide. 
 
 "Add some whiff of alcohol (methanol) to this mixutre, paired with the vinegar-like aroma of sulphur dioxide and a hint of the sweet aromatic scent of carbon disulphide, and you arrive at the 'perfume' of our comet." 
 
 The detection of so many different molecules at this stage has been a surprise, ESA said. 
 
 The Rosina team believed only the most volatile molecules—carbon dioxide and carbon monoxide—would be released as the comet's icy surface started slowly to warm. 
 
 On a 6.5-year orbit, 67P/C-G is the target of an ambitious mission to shed light on the origins of comets, ancient travellers of the Solar System. 
 
 Rosetta caught up with it after a six-billion-kilometre (3.75-billion-mile) trek that required four flybys of Earth and Mars, using the planets' gravity as a slingshot to build up speed. 
 
 It is now in close orbit around the comet at a distance of around 400 million kilometres from the Sun. The scout will send down a robot lander, Philae, on November 12 to carry out on-the-spot scientific tests. 
 
 On August 13 next year, the comet and Rosetta will be 185 million kilometres from the Sun, their closest approach to our star. 
 
 Explore further: Comet-chasing probe closes in on target ||||| With inputs from Kathrin Altwegg, ROSINA science team, University of Bern. 
 
 Since early August, the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) has been ‘sniffing the fumes’ of 67P/C-G with its two mass spectrometers. 
 
 As reported previously in this blog, even though the comet is still more than 400 million kilometres from the Sun, the mixture of molecules detected in the comet’s coma is surprisingly rich already. Before arriving at 67P/C-G, the ROSINA team thought that at these vast distances from the Sun, its relatively low intensity would only release the most volatile molecules via sublimation, namely carbon dioxide and carbon monoxide. 
 
 However, ROSINA has detected many more molecules. Indeed, as of our 11 September report, ROSINA’s inventory of detected gases 67P/C-G looked like this: 
 
 Water (H 2 O) 
 
 Carbon monoxide (CO) 
 
 Carbon dioxide (CO 2 ) 
 
 Ammonia (NH 3 ) 
 
 Methane (CH 4 ) 
 
 Methanol (CH 3 OH) 
 
 But today we can report that the following have also been detected: 
 
 Formaldehyde (CH 2 O) 
 
 Hydrogen sulphide (H 2 S) 
 
 Hydrogen cyanide (HCN) 
 
 Sulphur dioxide (SO 2 ) 
 
 Carbon disulphide (CS 2 ) 
 
 If you could smell the comet, you would probably wish that you hadn’t 🙂 
 
 As the Kathrin Altwegg, principal investigator for ROSINA, put it: “The perfume of 67P/C-G is quite strong, with the odour of rotten eggs (hydrogen sulphide), horse stable (ammonia), and the pungent, suffocating odour of formaldehyde. This is mixed with the faint, bitter, almond-like aroma of hydrogen cyanide. Add some whiff of alcohol (methanol) to this mixture, paired with the vinegar-like aroma of sulphur dioxide and a hint of the sweet aromatic scent of carbon disulphide, and you arrive at the ‘perfume’ of our comet.” 
 
 While this is unlikely to be a particularly attractive perfume, remember that the density of these molecules is very low, and that the main part of the coma is made up of water and carbon dioxide, mixed with carbon monoxide. 
 
 The key point, however, is that a detailed analysis of this mixture and how it varies as 67P/C-G grows more active will allow scientists to determine the comet’s composition. Further work will show how 67P/C-G compares with other comets, for example by revealing differences between comets originating from the Kuiper Belt (like 67P/C-G) and comets that hail from the distant Oort cloud (like Comet Siding Spring, which recently flew past Mars). The goal is to gain insights into the fundamental chemical make-up of the solar nebula from which our Solar System and, ultimately, life itself emerged. 
 
 *For a simple explanation of mass spectra and associated units, see Wikipedia’s entry: http://en.wikipedia.org/wiki/Mass_spectrum 
 
 For more detailed information on ROSINA, see our description here. ||||| View Images As Philae closes in for a landing, the shadow-pocked surface of the comet 67P is revealed. 
 
 Photograph by ESA/Rosetta/Philae 
 
 A misfire of harpoons, an ancient technology, may have spelled the end of one of the most advanced: Philae, the first spacecraft to send images from the surface of a comet. Unanchored to its comet, the spacecraft drifted into darkness, sending back scientific data even as its solar-powered batteries faded. 
 
 The lander successfully delivered data on the composition of the comet, before losing contact early Friday with the European Space Agency at the Rosetta Mission Operations Centre in Darmstadt, Germany. 
 
 "With its batteries depleted and not enough sunlight available to recharge, Philae has fallen into 'idle mode' for a potentially long silence," an ESA statement announced. 
 
 "It was a very successful mission; it has returned a lot of great data already," said space scientist Alan Stern of the Southwest Research Institute in Boulder, Colorado, a member of the Rosetta science team. 
 
 When Rosetta was originally designed more than a decade ago, the comet lander Philae was conceived of as a 24-hour mission, he says. "People are focusing on the wrong thing to ignore the success of carrying a lander to a comet and getting it on the surface." 
 
 The lander detached from the Rosetta spacecraft orbiting 13.7 miles (22 kilometers) above comet 67P Churyumov–Gerasimenko on Wednesday, landing on the 3.1-mile-long (5-kilometer-long) comet that same day. 
 
 During the landing at its intended site, called Agilkia, the lander's stabilizing rocket and two anchoring harpoons failed to fire. 
 
 On Earth, Philae weighs 187 pounds (85 kilograms), but gravity is so weak on Comet 67P—hundreds of thousands of times weaker than Earth—that it weighs about an ounce there. The harpoons were intended to keep the probe from drifting off the surface of the comet. 
 
 Instead, the unsecured lander bounced off the comet's surface, touching down again nearly two hours later, and then bouncing once more before finally settling, apparently in a shadowed crater beside a cliff. (See "Space Probe Philae Bounces on a Comet.") 
 
 Japan's Hayabusa spacecraft, which landed on an asteroid in 2005, encountered similar travails. Its MINERVA mini-lander was designed to hop on the space rock but instead drifted into space. 
 
 In the shadows, the solar panels of Philae failed to recharge, leaving it helpless after its 2.5-day batteries died. "From now on, no contact would be possible unless sufficient sunlight falls on the solar panels to generate enough power to wake it up," said mission controllers. 
 
 There is some hope of rousing Philae from its sleep. Before the lander shut down, mission controllers rotated Philae's main body about 125 degrees (some 35 percent of the way around its axis), which should have shifted its main solar panel. "This may have exposed more panel area to sunlight," said the ESA, perhaps allowing the lander's batteries to recharge. 
 
 Even if Philae is never revived, the mission will continue to deliver more new science. Scientists are analyzing data from Philae's final communication, and will receive much more information from the Rosetta orbiter, expected to keep orbiting the comet until December 2015. 
 
 The orbiter, currently about 14 miles (22.5 kilometers) away from 67P, will slowly spiral in until it's only a mile or two from the comet's surface, at which point its cameras will be able to pick out details just a few inches across. 
 
 Light reflected from the surface and into spectrographs will tell scientists the contents of 67P's outer crust. 
 
 Rosetta will also add to Philae's data on the composition of gases released from the interior. Already, the orbiter has detected hydrogen sulfide, ammonia, formaldehyde, and hydrogen cyanide along with water and carbon dioxide. 
 
 As the comet makes its closest approach to the sun next summer, the orbiter will study the comet as it heats up. 
 
 Michael D. Lemonick contributed to this article. ||||| Spacecraft’s final descent to the surface of the duck-shaped comet marks the end of an extraordinary journey – and will give ESA scientists ‘emotional closure’ 
 
 “Comets, importing change of times and states, brandish your crystal tresses in the sky,” Shakespeare wrote in Henry VI, Part 1, in a nod to the age-old belief in the divine influence of the small, icy bodies. 
 
 When the Rosetta spacecraft touches down on the surface of its chosen chunk of dust, ice and rock on Friday, it will mark the end of the mission that has dispelled the cloud of mystery and superstition that has surrounded comets for millennia. 
 
 Rosetta space probe to end mission with comet landing - live Read more 
 
 Since the craft arrived at 67P/Churyumov–Gerasimenko in August 2014, the $1bn European Space Agency (ESA) mission has revealed what comets look like (sometimes duck-shaped), what they’re made of and that - far from being portents of doom - comets helped seed life on Earth. 
 
 But it was probably the sheer audacity of attempting to land Rosetta’s tiny robotic probe, Philae, on an irregular lump of dust, ice and rock 405m kilometres (252m miles) from Earth, that won the world over two years ago. 
 
 “Rosetta has been comparable to the moon landing,” said Andrea Accomazzo, ESA’s spacecraft operations manager. “It’s that order of magnitude. As a child, I could only have dreamt something like this. It’s interesting to see how many emotions landing on a comet still triggers in very many people.” 
 
 Facebook Twitter Pinterest Rosetta’s Osiris wide-angle camera captured this image of Comet 67P/Churyumov-Gerasimenko from about 15.5 km above the surface. Photograph: ESA 
 
 Comet 67P is now heading out towards the orbit of Jupiter, and as it speeds away from the sun, Rosetta’s solar power supply is flagging, leaving the craft with only enough energy for one final manoeuvre. 
 
 Late on Thursday, Accomazzo and his team at ESA headquarters in Darmstadt in western Germany placed Rosetta on a collision course with the “head” of the comet, aiming for a region marked by pits, “goosebump” structures and jets of gas. 
 
 In the final moments of its descent, around noon on Friday (BST), Rosetta will train its cameras on 67P and take its last image around 15 metres from the surface, before (hopefully) softly touching down and switching off its transmitter. About 40 minutes later, mission control will receive the last close-up photograph of 67P. Then radio silence will mark the end of Rosetta’s 12-and-a-half year voyage through space. 
 
 Mission controllers will never be certain of the probe’s fate, but are aiming for a gentle landing that will leave it resting on the surface. “We could have abandoned it in space or let it bounce off the comet and just switched it off. It wouldn’t have created any problem,” said Accomazzo. “Landing it is more a psychological thing.” 
 
 As scientists switch their attention away from the delicate task of controlling a very distant spacecraft to analysing its data, some of Rosetta’s most impressive findings may lie in the future. It has already provided some remarkable insights. 
 
 An early surprise was simply the appearance of 67P – the comet’s “dirty snowball” nickname had led even scientists to expect something more bland and uniform in appearance. 
 
 Professor Monica Grady, a space scientist at the Open University who works on Ptolemy, one of Philae’s gas and dust detectors, recalls being “knocked out” by the first detailed surface imagery. “You’d expect them to be dusty and eroded, not these startling landscapes,” she said. “You try to interpret things in terms of what we know on Earth, like glaciers or river valleys, but that’s just not happened on the comet. We need to work out how these landscapes formed. And certainly no one expected it to be duck-shaped.” 
 
 Björn Davidsson, a Rosetta scientist based at Nasa’s jet propulsion laboratory, said the mission had revealed 67P was extremely porous, with around 70% of its volume being empty space. “When you see these beautiful images of the comet you should not think of it as rock,” he said. “It’s something like spun sugar or cotton candy – something very, very fluffy.” 
 
 Mission scientists were also caught off-guard by jets of dust from the comet, so vigorous that at one stage Rosetta’s star trackers, which help it navigate, were “blinded” and the craft had to be moved away to a safe distance. 
 
 Understanding the composition of comets gives scientists a snapshot of the materials that were blowing around in the clouds of dust and gas from which the planets in our solar system formed around 4.6bn years ago. Comets have essentially been in a deep freeze ever since, making them valuable time capsules. 
 
 Joel Parker, who works on Rosetta’s Alice instrument, an ultraviolet spectrograph, said: “Comets formed in the cold frozen wastelands of the outer solar system. They’re the remnants of the early solar system that didn’t get to form into planets.” 
 
 Before Rosetta, scientists speculated that comets may have delivered up to half the water on Earth during the heavy bombardment 4bn years ago, when comets and asteroids rained down onto the Earth’s surface (the rest of the water being released from the Earth’s interior). 
 
 However, measurements of 67P showed that its ice has a much higher fraction of deuterium – a heavy form of hydrogen – than water found on Earth. Scientists regard the heavy water ratio as a kind of astronomical fingerprint. 
 
 Facebook Twitter Pinterest Another image of Comet 67P/Churyumov-Gerasimenko during the spacecraft’s final descent on 30 September. Photograph: ESA 
 
 Gerhard Schwehm, Rosetta’s former mission manager, said: “It now looks like comets weren’t the objects that brought water to Earth, or not the main objects at least.” 
 
 Observations of the fuzzy cloud of dust and gas – the “coma” – that envelops 67P, have also revealed traces of the chemical building blocks of life. The findings support the notion that comets delivered some necessary ingredients for life to Earth, and also allow scientists to re-imagine exactly which chemicals were being stirred into the mix. 
 
 The Rosina instrument, a mass spectrometer on board Rosetta, detected the amino acid glycine, as well as the chemicals from which it is formed, methylamine and ethylamine. It also found phosphorus, a key component of DNA. 
 
 “This is what must have been in the primordial soup,” said Schwehm. 
 
 Schwehm, who has worked on the mission since its inception, said ESA’s original plan had been to bring comet samples back to Earth, but this was eventually deemed too expensive and risky. “We decided if we could not get the comet to the laboratory, we’d get the laboratory to the comet,” he said. “Surprisingly, it worked.” 
 
 The mission has not been without hair-raising moments for those involved. 
 
 For Accomazzo, nerves peaked when Rosetta’s internal hardware tripped and rebooted as it came out of a three-year period in hibernation mode in early 2014, causing a 15-minute delay in scientists receiving the craft’s “phone home” confirmation that it was still alive. Despite knowing that all the technical groundwork had been laid, he admits thinking: “This is crazy, how can this thing fly for three years on its own through space?” 
 
 For Grady, the highlight was the Philae landing, in November 2014, when footage of the eminent space scientist whooping and eventually weeping with joy went viral on Twitter. Aside from the birth of her son, she admits, “nothing is ever going to top that”. 
 
 After the initial celebrations, mission scientists later realised that Philae had bounced across the surface before coming to land in a shady spot beneath a cliff. Philae’s batteries drained within a couple of days and, after briefly waking up again a couple of times as the comet approached the sun, it was never heard from again. 
 
 Despite things not going entirely to plan, Grady estimates that Philae still carried out 80-85% of the work it was scheduled to do. And in a moment that mission scientists described as “emotional closure”, Rosetta finally managed to spot the washing machine-sized lander on the surface earlier this month. 
 
 As dust settles on the Rosetta craft – assuming the landing goes to plan – mission scientists are holding a celebratory barbecue to avoid things getting too maudlin. 
 
 “It will be very sad”, Grady said. “It’s been a big part of our lives for such a long time.” she adds. “In six years, the comet will be back again. We won’t be able to speak to it, but you’ll be able to look up and know Rosetta’s a bit closer to us.” 
 
 Professor Mark McCaughrean, the senior science advisor at the ESA, told BBC Radio 4 it was a sad day as he reflected on what the Rosetta mission had achieved 
 
 “It’s giving us a real insight into the building blocks of the solar system and the material which could have formed life on the earth, not life itself but the raw building blocks,” he said. 
 
 “But more importantly for me, it’s engaged the public in a way which is just unparalleled for a robotics space mission. The enthusiasm I see on the faces of kids around the world when I give talks and the public following online it’s going to be very sad day but a very proud day for everyone that’s been involved.”
– Comets stink, and not just because they have the potential to cause cataclysmic devastation if they ever came hurtling through our atmosphere and made impact with Earth. These "cosmic snowballs of frozen gases, rock, and dust roughly the size of a small town" (as described by NASA) literally stink to high heaven, according to scientists at Switzerland's University of Bern. One comet does, anyway: Researchers analyzed the "perfume" of comet 67P/Churyumov-Gerasimenko and said that its BO is apparently a combo of "rotten eggs, horse urine, formaldehyde, bitter almonds, alcohol, vinegar, and a hint of sweet ether," the AP reports. "If you could smell the comet, you would probably wish that you hadn't," reads a blog post on the European Space Agency site. The scientists were able to surmise what the comet would smell like by examining the gas emitted by the "coma," the comet's head, Phys.org reports. Luckily, instead of a squeamish human, a mass spectrometer aboard the space probe Rosetta was assigned the task of parsing out the perfumed molecules of 67P, including ammonia, methane, hydrogen sulfide, hydrogen cyanide, and "the pungent, suffocating (odor) of formaldehyde," notes the ESA post. The probe caught up to the comet in August after chasing it nearly 4 billion miles; it will be sending its Philae robot lander onto the comet proper on Nov. 12, NASA reports. And it appears the comet's odoriferous odyssey is just beginning: The lead scientist on the project says that as 67P gets closer to the sun, it will start stinking up the cosmos even more. (Whatever happened to NASA's plans to harpoon comets?)