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.
The largest sunspot to appear on Earth’s nearest star in more than two decades is once again pointed at the planet, and it will likely kick-start solar storms, NASA scientists say.
The massive sunspot, previously known as Active Region 12192, was turned toward Earth in October and early November, but rotated out of view. While it was on the Earth-facing side of the sun, the sunspot did not produce any coronal mass ejections — hot bursts of material ejected into space at 4 million mph (6.4 million kilometers/hour) — which have the potential to damage satellites and power grids. Now the active region has rotated back around to face Earth again, and although the sunspot has shrunk in size, it will likely be disruptive, NASA scientist Holly Gilbert told Space.com during a video interview about the massive sunspot.
“This time around, it’s more likely to have some coronal mass ejections associated with it, even though the solar flares might be smaller,” said Gilbert, chief of the Solar Physics Laboratory at NASA’s Goddard Space Flight Center in Maryland. “We have a good idea, based on the structure of that magnetic field and the sunspot, that it’s very possible that it will create some midlevel flares.”
Sunspots are blemish-like regions on the sun where magnetic fields become very tightly bundled. The magnetic fields block light and heat from passing through the sunspot region, causing them to appear dark compared to the surrounding area.
AR 12192 has been renamed AR 12209 now that it is once again on the Earth-facing side of the sun. The sunspot was out of view of the Earth for about two weeks before reappearing. It is still large enough for 10 Earths to fit inside it, Gilbert said. In terms of size, it ranks 33rd largest of 32,908 active regions recorded since 1874, and it’s the largest sunspot recorded since 1990.
The huge spot released six major solar flares in Earth’s direction in October and early November, plus a series of smaller flares, before moving to the side of the sun facing away from Earth. Solar flares can lead to the production of coronal mass ejections, also called CMEs, and Gilbert said it was “a little strange” that the major solar flares produced by AR 12192 did not result in any CMEs.
“[CMEs] can affect our satellites, our technology; it can cause power grid outage,” Gilbert said. “So it’s very important for us to understand when they’re going to happen and how they’re going to impact us here on Earth.”
Scientists cannot yet predict when a sunspot will produce flares or if those flares will kick up coronal mass ejections. But NASA knows when these flares and CMEs occur, thanks to a fleet of satellite missions that are studying the sun and its effect on the Earth. NASA’s Solar Dynamics Observatory, which was designed to study the causes of space weather and how it affects Earth, monitors the sun around the clock.
AR 12209 will continue to shrink and will eventually disappear, but it could make another trip around the sun before it goes away completely. The sun is currently headed into a phase of minimal solar activity, during which scientists expect fewer active regions to appear.
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.”
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.
At one of the world’s deepest undersea hydrothermal vents, tiny shrimp are piled on top of each other, layer upon layer, crawling on rock chimneys that spew hot water. Bacteria, inside the shrimps’ mouths and in specially evolved gill covers, produce organic matter that feed the crustaceans.
Scientists at NASA’s Jet Propulsion Laboratory in Pasadena, California, are studying this mysterious ecosystem in the Caribbean to get clues about what life could be like on other planetary bodies, such as Jupiter’s icy moon Europa, which has a subsurface ocean.
“For two-thirds of the Earth’s history, life has existed only as microbial life,” said Max Coleman, senior research scientist at JPL. “On Europa, the best chance for life would be microbial.”
The particular bacteria in the vents are able to survive in extreme environments because of chemosynthesis, a process that works in the absence of sunlight and involves organisms getting energy from chemical reactions. In this case, the bacteria use hydrogen sulfide, a chemical abundant at the vents, to make organic matter. The temperatures at the vents can climb up to a scorching 750 degrees Fahrenheit (400 degrees Celsius), but waters just an inch away are cool enough to support the shrimp. The shrimp are blind, but have thermal receptors in the backs of their heads.
“The overall objective of our research is to see how much life or biomass can be supported by the chemical energy of the hot submarine springs,” Coleman said.
Hydrogen sulfide is toxic to organisms in high concentrations, but the bacteria feeding the shrimp need a certain amount of this chemical to survive. Nature has worked out a solution: The shrimp position themselves on the very border between normal, oxygenated ocean water and sulfide-rich water so that they and the bacteria can coexist in harmony.
“It’s a remarkable symbiotic system,” Coleman said.
Coleman was part of a team led by Chris German at the Woods Hole Oceanographic Institution, in Woods Hole, Massachusetts, that discovered these vents in 2009, off the west coast of Cuba. This research, funded under NASA’s Astrobiology Science and Technology for Exploring Planets program, detected the vents by picking up the chemical signals of their plumes of water in the ocean.
The researchers returned in 2012 on the RV Atlantis with a robotic vehicle called Jason, supported by the National Science Foundation. Scientists collected extensive specimens from two hydrothermal vent fields: The Von Damm field at 7,500 feet (2,300 meters) and Piccard at more than 16,000 feet (4,900 meters), which is the world’s deepest.
Coleman and collaborator Cindy Van Dover, marine biologist at Duke University, Durham, North Carolina, examined the shrimp for the first time when the same team returned in 2013 on the RV Falkor, provided by the Schmidt Ocean Institute in Palo Alto, California. Van Dover returned soon after using the robotic vehicle Hercules aboard the Exploration Vessel Nautilus, and did more collections and studies.
A bonus finding from studying this extreme oasis of life is that some of the shrimp, called Rimicaris hybisae, appear to be cannibalistic. The researchers discovered that when the shrimp arrange themselves in dense groups, bacteria seem to be the main food supplier, as the shrimp likely absorb the carbohydrates that the bacteria produce. But in areas where the shrimp are distributed more sparsely, the shrimp are more likely to turn carnivorous, eating snails, other crustaceans, and even each other.
Although the researchers did not directly observe Rimicaris hybisae practicing cannibalism, scientists did find bits of crustaceans in the shrimps’ guts. And Rimicaris hybisae is the most abundant crustacean species in the area by far.
“Whether an animal like this could exist on Europa heavily depends on the actual amount of energy that’s released there, through hydrothermal vents,” said Emma Versteegh, a postdoctoral fellow at JPL.
The group received funding for shrimp-collecting expeditions from NASA’s Astrobiology Science and Technology for Exploring Planets (ASTEP) program, through a project called “Oases for Life.” That name is especially appropriate for this investigation, Coleman said.
“You go along the ocean bottom and there’s nothing, effectively,” Coleman said. “And then suddenly we get these hydrothermal vents and a massive ecosystem. It’s just literally teeming with life.”
This research was conducted in collaboration with the Woods Hole Oceanographic Institution and Duke University. The Schmidt Ocean Institute provided technical and financial support for marine and underwater robotic operations during the 2013 RV Falkor cruise. The California Institute of Technology in Pasadena manages JPL for NASA.