A peculiar mix of molecular nitrogen on the comet target of Europe's Rosetta spacecraft may offer clues to the conditions that gave birth to the entire solar system.
Molecular nitrogen was one of the key ingredients of the young solar system. Its detection in Comet 67P/Churyumov–Gerasimenko, which Rosetta is currently orbiting, suggests that the comet formed under low-temperature conditions (a requirement to keeping nitrogen as ice), according to officials with the European Space Agency.
Since nitrogen is also found in planets and moons in the outer solar system, Rosetta's discovery implies that 67P's family of comets formed in the same area, ESA said.
The Rosetta spacecraftdetected the molecular nitrogen using the probe's ROSINA instrument (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) between Oct. 17 and 23, 2014. At the time, Rosetta was orbiting just 6.2 miles (10 kilometers) from Comet 67P's center.
But the finding also carried a surprise: The ratio of molecular nitrogen to carbon monoxide in the comet was 25 times less than what was expected from models of the early solar system. (Carbon monoxide is important for the measurements, because the ice that trapped the molecular nitrogen likely formed at similar temperatures as those needed to trap carbon monoxide.)
Scientists said the unexpectedly low ratio resulted from the way ice is formed at extremely low temperatures. Perhaps the molecular nitrogen was trapped inside "cagelike" water-ice called clathrates, at temperatures between minus 418 Fahrenheit and minus 364 Fahrenheit (minus 250 Celsius and minus 220 Celsius), ESA said.
Alternatively, scientists suggest the ice could have trapped the molecular nitrogen at a temperature of roughly minus 423 F (minus 253 C). This would make sense if 67P had been in the same region of the solar system as Triton and Pluto, which both have nitrogen in their ices.
Regardless of the origin story, 67P would have released the nitrogen as it drew closer to the sun, which caused the comet's ice to melt. This could explain the low ratio, scientists said.
The results were published in the journal Science and led by Martin Rubin, who is with the space research and planetary sciences division of the University of Bern in Switzerland.
Source: Elizabeth Howel
With the Philae lander’s mission complete, Rosetta will now continue its own extraordinary exploration, orbiting Comet 67P/Churymov–Gerasimenko during the coming year as the enigmatic body arcs ever closer to our Sun.
Last week, ESA’s Rosetta spacecraft delivered its Philae lander to the surface of the comet for a dramatic touchdown.
The lander’s planned mission ended after about 64 hours when its batteries ran out, but not before it delivered a full set of results that are now being analysed by scientists across Europe.
Rosetta’s own mission is far from over and the spacecraft remains in excellent condition, with all of its systems and instruments performing as expected.
“With lander delivery complete, Rosetta will resume routine science observations and we will transition to the ‘comet escort phase’,” says Flight Director Andrea Accomazzo.
“This science-gathering phase will take us into next year as we go with the comet towards the Sun, passing perihelion, or closest approach, on 13 August, at 186 million kilometres from our star.”
Rosetta control room
On 16 November, the flight control team moved from the large Main Control Room at ESA’s Space Operations Centre in Darmstadt, Germany, where critical operations during landing were performed, to a smaller Dedicated Control Room, from where the team normally flies the craft.
Since then, Rosetta has performed a series of manoeuvres, using its thrusters to begin optimising its orbit around the comet for the 11 scientific instruments.
“Additional burns planned for today, 22 and 26 November will further adjust the orbit to bring it up to about 30 km above the comet,” says Sylvain Lodiot, Spacecraft Operations Manager.
From next week, Rosetta’s orbit will be selected and planned based on the needs of the scientific sensors. After arrival on 6 August, the orbit was designed to meet the lander’s needs.
Getting as close as feasible
On 3 December, the craft will move down to height of 20 km for about 10 days, after which it will return to 30 km.
Rosetta path after 12 November
With the landing performed, all future trajectories are designed purely with science as the driver, explained Laurence O’Rourke and Michael Küppers at the Rosetta Science Operations Centre near Madrid, Spain.
“The desire is to place the spacecraft as close as feasible to the comet before the activity becomes too high to maintain closed orbits,” says Laurence.
“This 20 km orbit will be used by the science teams to map large parts of the nucleus at high resolution and to collect gas, dust and plasma at increasing activity.”
Planning the science orbits involves two different trajectories: ‘preferred’ and ‘high-activity’. While the intention is always to fly the preferred path, Rosetta will move to the high-activity trajectory in the event the comet becomes too active as it heats up.
“This will allow science operations to continue besides the initial impact on science planning that such a move would entail,” adds Michael.
Science takes a front seat
“Science will now take front seat in this great mission. It’s why we are there in the first place!” says Matt Taylor, Rosetta Project Scientist.
“The science teams have been working intensively over the last number of years with the science operations centre to prepare the dual planning for this phase.”
When solar heat activates the frozen gases on and below the surface, outflowing gas and dust particles will create an atmosphere around the nucleus, known as the coma.
First spacecraft to track a comet toward the Sun
Rosetta will become the first spacecraft to witness at close quarters the development of a comet’s coma and the subsequent tail streaming for millions of kilometres into space. Rosetta will then have to stay further from the comet to avoid the coma affecting its orbit.
In addition, as the comet nears the Sun, illumination on its surface is expected to increase. This may provide sufficient sunlight for the DLR-operated Philae lander, now in hibernation, to reactivate, although this is far from certain.
Early next year, Rosetta will be switched into a mode that allows it to listen periodically for beacon signals from the surface.
More about Rosetta
Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI.
Regular updates on Rosetta’s continuing mission and its scientific explorations will be posted in the mission blog, via http://blogs.esa.int/rosetta.
Source: European Space Agency
SESAME experiment CASSE records sound of first landing
A short but significant ‘thud’ was heard by the Cometary Acoustic Surface Sounding Experiment (CASSE) as Philae made its first touchdown on Comet 67P/Churyumov-Gerasimenko. The two-second recording from space is the very first of the contact between a man-made object with a comet upon landing. The CASSE sensors are located in the feet at the base of all three legs of the lander and were active on 12 November 2014 during the descent to the comet. “The contact with the surface was short, but we can evaluate the scientific data,” says Martin Knapmeyer, a planetary scientist at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR) and scientific leader of the CASSE Team.
The signals acquired by the three lander feet are more enlightening for the researchers than might seem for the lay man: “The Philae lander came into contact with a soft layer several centimetres thick. Then, just milliseconds later, the feet encountered a hard, perhaps icy layer on 67P/Churyumov-Gerasimenko,” explains DLR researcher Klaus Seidensticker, who is responsible for the Surface Electric Sounding and Acoustic Monitoring Experiment (SESAME), which includes CASSE.
Listening to the touchdown
During the descent phase, CASSE initially detected vibrations from the flywheel that stabilised the flight. Upon its first contact with the comet’s surface, Philae bounced because the harpoons intended to anchor it as it touched down failed to deploy. “From our data, we can determine that no second landing occurred immediately after the first bounce,” explains Knapmeyer. Together with data from the ROMAP instrument, it has been determined that Philae did not immediately return to the comet surface after the first touchdown and bounce during the evening of 12 November.
Philae landed a total of three times, finally coming to rest on the surface at 18:32 CET and immediately starting to conduct the next measurements. CASSE transmitted and received vibrations from the lander’s feet to determine the mechanical properties of the comet surface. CASSE also detected vibrations as the MUPUS instrument attempted to hammer a probe deep into the hard surface material.
Search for dust and water ice
The two other components of SESAME, the Dust Impact Monitor (DIM) and the Permittivity Probe (PP) experiments, performed measurements and sent data back to Earth during Philae’s more than 60 hours of operation. Initial analyses of data from DIM suggest that the final landing site on 67P/Churyumov-Gerasimenko – at the edge of a crater – is not currently active. No particles were detected, which suggests that no dust is moving in the immediate vicinity of the lander. The PP experiment used a number of electrodes to transmit alternating current through the comet surface and was able to detect that there is a large quantity of water ice under Philae.
On 12 November 2014, shortly after the first touchdown, it became clear to the team at the DLR Lander Control Center that the harpoons had not fired and that the Philae lander had very likely rebounded. DLR researcher Klaus Seidensticker initially feared an unfavourable outcome for the mission: “But now we have much more data than I had hoped for.”
Source: Jet Propulsion Laboratory
The Philae space probe was powered down earlier than expected, but not before an instrument discovered an organic compound that was first detected in the comet’s atmosphere, the Wall Street Journal exclusively reported Monday. The find is extraordinary considering the organic compound contains the carbon atom, which is the basis of life on planet Earth.
Further research is being conducted to see if there are complex compounds like amino acids or simple ones like methane and methanol, considered “building blocks” for proteins.
The research “will help us to understand whether organic molecules were brought by comets to the early earth,” Stephan Ulamec, the Philae’s landing manager said, according to the Journal.
A probe named Philae is seen after it landed safely on a comet, known as 67P/Churyumov-Gerasimenko, in this CIVA handout image released Nov. 13, 2014. Reuters/ESA Handout
The European Space Agency (ESA) said the probe fell into hibernation after it only got 1.5 hours of light a day instead of the expected seven. Even though Philae “fell silent,” it was still able to send the information it retrieved while it was functioning — that’s how the organic compound discovery was found.
“Prior to falling silent, the lander was able to transmit all science data gathered during the First Science Sequence,” Ulamec said. “This machine performed magnificently under tough conditions, and we can be fully proud of the incredible scientific success Philae has delivered.”
Before it went idle, Philae conducted 60 hours of work on Comet 67P, The Conversation said. One of its missions was to ascertain if complex organic molecules, which could have helped create Earth billions of years ago, existed on comets.
Philae’s landing was not only historical, but also a hit on social media. Philae’s monumental landing arguably overshadowed reality star Kim Kardashian’s nude photos from Paper magazine, even though the starlet intended to “break the internet.” Data showed more people talked about Philae’s landing by nearly 170,000 tweets, the Journal wrote in another article, citing Topsy. There were 479,434 tweets in 24 hours about the comet landing, while Kardashian had 307,782 mentions in the same time period.
Sorry for the delay to post this article, but we had to deal with some technical issues, and we could not let this article pass by with being posted! 🙂
ESA’s Rosetta mission has soft-landed its Philae probe on a comet, the first time in history that such an extraordinary feat has been achieved.
After a tense wait during the seven-hour descent to the surface of Comet 67P/Churyumov–Gerasimenko, the signal confirming the successful touchdown arrived on Earth at 16:03 GMT (17:03 CET).
The confirmation was relayed via the Rosetta orbiter to Earth and picked up simultaneously by ESA’s ground station in Malargüe, Argentina and NASA’s station in Madrid, Spain. The signal was immediately confirmed at ESA’s Space Operations Centre, ESOC, in Darmstadt, and DLR’s Lander Control Centre in Cologne, both in Germany.
The first data from the lander’s instruments were transmitted to the Philae Science, Operations and Navigation Centre at France’s CNES space agency in Toulouse.
“Our ambitious Rosetta mission has secured a place in the history books: not only is it the first to rendezvous with and orbit a comet, but it is now also the first to deliver a lander to a comet’s surface,” noted Jean-Jacques Dordain, ESA’s Director General.
“With Rosetta we are opening a door to the origin of planet Earth and fostering a better understanding of our future. ESA and its Rosetta mission partners have achieved something extraordinary today.”
“After more than 10 years travelling through space, we’re now making the best ever scientific analysis of one of the oldest remnants of our Solar System,” said Alvaro Giménez, ESA’s Director of Science and Robotic Exploration.
“Decades of preparation have paved the way for today’s success, ensuring that Rosetta continues to be a game-changer in cometary science and space exploration.”
“We are extremely relieved to be safely on the surface of the comet, especially given the extra challenges that we faced with the health of the lander,” said Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center.
“In the next hours we’ll learn exactly where and how we’ve landed, and we’ll start getting as much science as we can from the surface of this fascinating world.”
Rosetta was launched on 2 March 2004 and travelled 6.4 billion kilometres through the Solar System before arriving at the comet on 6 August 2014.
“Rosetta’s journey has been a continuous operational challenge, requiring an innovative approach, precision and long experience,” said Thomas Reiter, ESA Director of Human Spaceflight and Operations.
“This success is testimony to the outstanding teamwork and the unique knowhow in operating spacecraft acquired at the European Space Agency over the decades.”
Following a period spent at 10 km to allow further close-up study of the chosen landing site, Rosetta moved onto a more distant trajectory to prepare for Philae’s deployment.
Five critical go/no-go decisions were made last night and early this morning, confirming different stages of readiness ahead of separation, along with a final preseparation manoeuvre by the orbiter.
Deployment was confirmed at 09:03 GMT (10:03 CET) at a distance of 22.5km from the centre of the comet. During the seven-hour descent, which was made without propulsion or guidance, Philae took images and recorded information about the comet’s environment.
“One of the greatest uncertainties associated with the delivery of the lander was the position of Rosetta at the time of deployment, which was influenced by the activity of the comet at that specific moment, and which in turn could also have affected the lander’s descent trajectory,” said Sylvain Lodiot, ESA Rosetta Spacecraft Operations Manager.
“Furthermore, we’re performing these operations in an environment that we’ve only just started learning about, 510 million kilometres from Earth.”
Touchdown was planned to take place at a speed of around 1 m/s, with the three-legged landing gear absorbing the impact to prevent rebound, and an ice screw in each foot driving into the surface.
But during the final health checks of the lander before separation, a problem was detected with the small thruster on top that was designed to counteract the recoil of the harpoons to push the lander down onto the surface. The conditions of landing – including whether or not the thruster performed – along with the exact location of Philae on the comet are being analysed.
The first images from the surface are being downlinked to Earth and should be available within a few hours of touchdown.
Over the next 2.5 days, the lander will conduct its primary science mission, assuming that its main battery remains in good health. An extended science phase using the rechargeable secondary battery may be possible, assuming Sun illumination conditions allow and dust settling on the solar panels does not prevent it. This extended phase could last until March 2015, after which conditions inside the lander are expected to be too hot for it to continue operating.
Science highlights from the primary phase will include a full panoramic view of the landing site, including a section in 3D, high-resolution images of the surface immediately underneath the lander, on-the-spot analysis of the composition of the comet’s surface materials, and a drill that will take samples from a depth of 23 cm and feed them to an onboard laboratory for analysis.
The lander will also measure the electrical and mechanical characteristics of the surface. In addition, low-frequency radio signals will be beamed between Philae and the orbiter through the nucleus to probe the internal structure.
The detailed surface measurements that Philae makes at its landing site will complement and calibrate the extensive remote observations made by the orbiter covering the whole comet.
“Rosetta is trying to answer the very big questions about the history of our Solar System. What were the conditions like at its infancy and how did it evolve? What role did comets play in this evolution? How do comets work?” said Matt Taylor, ESA Rosetta project scientist.
“Today’s successful landing is undoubtedly the cherry on the icing of a 4 km-wide cake, but we’re also looking further ahead and onto the next stage of this ground-breaking mission, as we continue to follow the comet around the Sun for 13 months, watching as its activity changes and its surface evolves.”
While Philae begins its close-up study of the comet, Rosetta must manoeuvre from its post-separation path back into an orbit around the comet, eventually returning to a 20 km orbit on 6 December.
Next year, as the comet grows more active, Rosetta will need to step further back and fly unbound ‘orbits’, but dipping in briefly with daring flybys, some of which will bring it within just 8 km of the comet centre.
The comet will reach its closest distance to the Sun on 13 August 2015 at about 185 million km, roughly between the orbits of Earth and Mars. Rosetta will follow it throughout the remainder of 2015, as they head away from the Sun and activity begins to subside.
“It’s been an extremely long and hard journey to reach today’s once-in-a-lifetime event, but it was absolutely worthwhile. We look forward to the continued success of the great scientific endeavour that is the Rosetta mission as it promises to revolutionise our understanding of comets,” said Fred Jansen, ESA Rosetta mission manager.