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| Rosetta Spacecraft Ends Mission With Dive Into Comet It Orbited | |
| (35 minutes later) | |
| Rosetta, the first spacecraft to orbit a comet, is dead, setting down in a final embrace with its companion of the past two years. | Rosetta, the first spacecraft to orbit a comet, is dead, setting down in a final embrace with its companion of the past two years. |
| Radio signals from Rosetta flatlined at 7:19 a.m. Eastern after it did a soft belly-flop onto Comet 67P/Churyumov-Gerasimenko at a speed of two miles per hour, slower than the average walk. | Radio signals from Rosetta flatlined at 7:19 a.m. Eastern after it did a soft belly-flop onto Comet 67P/Churyumov-Gerasimenko at a speed of two miles per hour, slower than the average walk. |
| For the last few minutes, people at the European Space Operations Center in Darmstadt, Germany, watched their computer screens mostly in silence, but with some nervous chatter. When the radio signals ceased, they applauded and hugged in a celebration that was part joyous, part somber. | For the last few minutes, people at the European Space Operations Center in Darmstadt, Germany, watched their computer screens mostly in silence, but with some nervous chatter. When the radio signals ceased, they applauded and hugged in a celebration that was part joyous, part somber. |
| “This is it,” said Patrick Martin, the mission manager. “I can announce the full success of this historic descent of Rosetta toward 67P, and I declare the primary mission operations ended for Rosetta.” | “This is it,” said Patrick Martin, the mission manager. “I can announce the full success of this historic descent of Rosetta toward 67P, and I declare the primary mission operations ended for Rosetta.” |
| Before Rosetta went silent, it collected and sent back one last batch of data and images, including some very close-up shots of the comet’s surface. | Before Rosetta went silent, it collected and sent back one last batch of data and images, including some very close-up shots of the comet’s surface. |
| The last photograph was taken at a height of 167 feet and was blurry because the camera was designed for viewing from a distance, not close up. | |
| The spacecraft’s 12-year journey — it took a decade to get there — concluded with quite a few firsts, and quite a few fans. | |
| Comets are frozen remnants that hold secrets about the early solar system, and Rosetta was the first spacecraft to do more than just whiz by one. Comet 67P, which probably formed outside of Neptune, was one of the few with an orbit that could be matched by a spacecraft. | |
| Two years of observation have revealed a dormant comet coming to life as it neared the sun and heated up, shooting geysers of dust and gas off its surface. Scientists learned that its shape, resembling a rubber duck, most likely occurred when two comets bumped into each other at a low velocity and stuck together. | Two years of observation have revealed a dormant comet coming to life as it neared the sun and heated up, shooting geysers of dust and gas off its surface. Scientists learned that its shape, resembling a rubber duck, most likely occurred when two comets bumped into each other at a low velocity and stuck together. |
| The European Space Agency created a series of cartoon videos for children. For an older audience it commissioned a short film, “Ambition,” which starred actors from the HBO series “Game of Thrones.” Aidan Gillen, who plays Petyr “Littlefinger” Baelish, and Aisling Franciosi, who plays Lyanna Stark, explained the mission’s grand goals with sci-fi storytelling: | The European Space Agency created a series of cartoon videos for children. For an older audience it commissioned a short film, “Ambition,” which starred actors from the HBO series “Game of Thrones.” Aidan Gillen, who plays Petyr “Littlefinger” Baelish, and Aisling Franciosi, who plays Lyanna Stark, explained the mission’s grand goals with sci-fi storytelling: |
| The film was released in October 2014, shortly before Rosetta dispatched a small lander, Philae, to the surface of Comet 67P. On Wednesday, the space agency released an epilogue: | The film was released in October 2014, shortly before Rosetta dispatched a small lander, Philae, to the surface of Comet 67P. On Wednesday, the space agency released an epilogue: |
| After making its closest approach to the sun in August 2015, Comet 67P is now on the outward leg of its orbit. As sunlight grew more faint, Rosetta was less able to generate power from its solar panels. | After making its closest approach to the sun in August 2015, Comet 67P is now on the outward leg of its orbit. As sunlight grew more faint, Rosetta was less able to generate power from its solar panels. |
| Mission managers decided on a dive to collect one last batch of data: close-up observations of mysterious pits that appear similar to sinkholes on Earth. | |
| The camera was expected to make out features as a small as one inch wide. | |
| “It will be interesting to get to look into the interior of the pits,” Mohamed Ramy El-Maarry, a postdoctoral researcher at the University of Bern in Switzerland, and a member of the team working with Rosetta’s high-resolution camera, said during a news conference on Thursday. | “It will be interesting to get to look into the interior of the pits,” Mohamed Ramy El-Maarry, a postdoctoral researcher at the University of Bern in Switzerland, and a member of the team working with Rosetta’s high-resolution camera, said during a news conference on Thursday. |
| The instrument that collected and studied dust particles had already been turned off. | The instrument that collected and studied dust particles had already been turned off. |
| During a series of presentations on Thursday, mission scientists described some of their findings, including a variety of “magical landscapes” along with an overall emptiness. They released audio of a “cosmic song,” created by the magnetic fields oscillating in the trail of particles flying off the comet. | During a series of presentations on Thursday, mission scientists described some of their findings, including a variety of “magical landscapes” along with an overall emptiness. They released audio of a “cosmic song,” created by the magnetic fields oscillating in the trail of particles flying off the comet. |
| Valerie Ciarletti of the Université Paris-Saclay, who helped investigate the comet’s interior with radio waves, said the inside of Comet 67P is about as porous as fresh, powdery snow — 70 percent of the volume is empty space. “It’s very fluffy material,” she said. | Valerie Ciarletti of the Université Paris-Saclay, who helped investigate the comet’s interior with radio waves, said the inside of Comet 67P is about as porous as fresh, powdery snow — 70 percent of the volume is empty space. “It’s very fluffy material,” she said. |
| Parts of the surface, like the rocky region where Rosetta’s lander Philae wound up, are more dense, with a porosity lower than 50 percent. “It could be something like sand,” Dr. Ciarletti said. | Parts of the surface, like the rocky region where Rosetta’s lander Philae wound up, are more dense, with a porosity lower than 50 percent. “It could be something like sand,” Dr. Ciarletti said. |
| The interior was also homogeneous. There were no big caves or large regions of compressed material. | The interior was also homogeneous. There were no big caves or large regions of compressed material. |
| Thurid Mannel, a scientist at the University of Graz in Austria, described a menagerie of dust particles spanning a wide range of sizes and materials. Many were shattered by the impact with the device on Rosetta that collected dust particles ejected from the comet. “The dust is very, very fragile,” she said. | Thurid Mannel, a scientist at the University of Graz in Austria, described a menagerie of dust particles spanning a wide range of sizes and materials. Many were shattered by the impact with the device on Rosetta that collected dust particles ejected from the comet. “The dust is very, very fragile,” she said. |
| The scientists learned much about the comet’s landscape. Dr. El-Maarry described its surface as very dark — reflecting just 3 to 4 percent of the sunlight that hits it. The darkness comes from a dearth of ice at the surface and an abundance of organic molecules. | The scientists learned much about the comet’s landscape. Dr. El-Maarry described its surface as very dark — reflecting just 3 to 4 percent of the sunlight that hits it. The darkness comes from a dearth of ice at the surface and an abundance of organic molecules. |
| Some areas are bare rock; others are smooth terrains buried in dust. “You can think of something like a sea of sand being surrounded by cliffs,” Dr. El-Maarry said. | Some areas are bare rock; others are smooth terrains buried in dust. “You can think of something like a sea of sand being surrounded by cliffs,” Dr. El-Maarry said. |
| The rocks are cracked with fissures. | The rocks are cracked with fissures. |
| “Anywhere we can see that surface and we have good enough resolution, we see fractures everywhere,” Dr. El-Maarry said. | “Anywhere we can see that surface and we have good enough resolution, we see fractures everywhere,” Dr. El-Maarry said. |
| Charlotte Goetz of the Technical University Braunschweig was among the scientists who studied the cloud of charged particles around the comet. When Rosetta first arrived, the interplay of particles from the comet with the solar wind produced oscillations in the magnetic fields that the scientists turned into sound, a “cosmic song.” | Charlotte Goetz of the Technical University Braunschweig was among the scientists who studied the cloud of charged particles around the comet. When Rosetta first arrived, the interplay of particles from the comet with the solar wind produced oscillations in the magnetic fields that the scientists turned into sound, a “cosmic song.” |
| Closer in, as more material spewed off the comet, the tune changed. Dr. Goetz on Thursday presented a longer song. | Closer in, as more material spewed off the comet, the tune changed. Dr. Goetz on Thursday presented a longer song. |
| But then as Rosetta and the comet moved away from the sun, the original song returned. | But then as Rosetta and the comet moved away from the sun, the original song returned. |
| At the end of Thursday’s presentations, Matt Taylor, the project scientist, thanked the other scientists who he said “worked their guts out to get to where we are today.” | At the end of Thursday’s presentations, Matt Taylor, the project scientist, thanked the other scientists who he said “worked their guts out to get to where we are today.” |
| He said they had mixed feelings: sad about Rosetta’s demise, and eager to take a deeper look at the reams of data. | He said they had mixed feelings: sad about Rosetta’s demise, and eager to take a deeper look at the reams of data. |
| “The operations end,” Dr. Taylor said, “but we still have all this science to do, so they’re still happy that we got to this stage.” |