The Rosetta spacecraft has crashed into a comet, bringing to an end one of the most important space missions in recent history.

Final preparations were made to send the craft into the comet that it has spent months circling, destroying the probe and ending operations on the £1bn mission.

The quest ended at around midday UK time, when the Rosetta craft hit the comet’s surface and Earth lost contact with it. Before then, scientists hoped to get their last pieces of information – some of which might be the most important ever spotted, since Rosetta will be able to get so close to the surface.

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Scientists working on the mission have spent recent days preparing to say goodbye to the craft, which they have been designing and steering through the solar system for years.

Tributes included a special box of tissues – ready for those scientists moved to tears by the poignant final stage of the mission – shaped like Rosetta itself.

Final commands were sent to the Rosetta craft, ordering it to begin a descent that saw it land on the rock’s surface. It is now destroyed and will lie on the comet’s surface, alongside the Philae lander, for millions of years as it flies around the sun.

Shape Created with Sketch. In pictures: European Space Agency's Rosetta mission Show all 22 left Created with Sketch. right Created with Sketch. Shape Created with Sketch. In pictures: European Space Agency's Rosetta mission 1/22 European Space Agency's Rosetta mission Image of Comet 67P/CG taken by the Philae lander from a distance of approximately 3km from the surface 2/22 European Space Agency's Rosetta mission Rosetta's lander Philae took this parting shot of its mothership shortly after separation 3/22 European Space Agency's Rosetta mission Parting shot of the Philae lander after separation, captured by one of Rosetta's cameras 4/22 European Space Agency's Rosetta mission A technician celebrates after the successful landing of the Philae lander, in the control room at the ESA headquarters in Darmstadt Reuters 5/22 European Space Agency's Rosetta mission Scientists celebrate at a mission observation centre in Toulouse, southern France as they receive information that Philae has landed on the Churyumov-Gerasimenko comet AP 6/22 European Space Agency's Rosetta mission Astronomer Klim Ivanovych Churyumov, who discovered the comet 67P/ Churyumov-Gerasimenko in 1969, reacts after the successful landing of the Philae lander on the comet Reuters 7/22 European Space Agency's Rosetta mission A model demonstrates how the landing device Philae, of the space probe Rosetta, stands on the comet 67P/Churyumov-Gerasimenko at the press center of the satellite control center of the European Space Agency in Darmstadt, Germany EPA 8/22 European Space Agency's Rosetta mission An artist impression of Rosetta's lander Philae on the surface of comet Getty Images 9/22 European Space Agency's Rosetta mission Picture taken on October 28 by the navigation camera on Rosetta shows the boulder-strewn neck region of comet 67/P Churyumov-Gerasimenko. It was captured from a distance of 9.7 km from the center of the comet Getty Images 10/22 European Space Agency's Rosetta mission Picture taken on October 24 shows a raised plateau on the larger lobe of the comet Getty Images 11/22 European Space Agency's Rosetta mission The probe is supposed to fly to a comet and put down a small laboratory on the top of it 12/22 European Space Agency's Rosetta mission A scientist from the European Space Agency with an airworthy copy of space probe 'Rosetta' in the control center in Darmstadt, Germany 13/22 European Space Agency's Rosetta mission Maneuvers designed for the actual space probe are simulated with the replica. 'Rosetta' will be woken up from an energy saving hibernation after 957 days 14/22 European Space Agency's Rosetta mission A European Space Agency employee sits in the control room for the Rosetta mission in Darmstadt, Germany 15/22 European Space Agency's Rosetta mission Scientists at the European Space Agency are expecting their comet-chasing probe Rosetta to wake from almost three years of hibernation 16/22 European Space Agency's Rosetta mission Europe's Rosetta probe on a NASA mission 17/22 European Space Agency's Rosetta mission NASA is participating in the European Space Agency's Rosetta mission, whose goal is to observe one such space-bound icy dirt ball from up close for months on end 18/22 European Space Agency's Rosetta mission An impression of the Philae lander 19/22 European Space Agency's Rosetta mission ESA probe Rosetta with Mars in the background. The three-tonne probe blasted off aboard an an Ariane V rocket from Kourou, French Guiana in 2004 20/22 European Space Agency's Rosetta mission Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko, the spacecraft measures 32 m across including the solar arrays, while the comet nucleus is thought to be about 4 km wide 21/22 European Space Agency's Rosetta mission The spacecraft, festooned with 25 instruments between its lander and orbiter (including three from NASA), is programmed to 'wake up' from hibernation 22/22 European Space Agency's Rosetta mission An Ariane V carrying the three-tonne probe Rosetta blasting off from Kourou, beginning a decade-long quest to hunt a comet in the depths of the Solar System and shadow it around the Sun in a bid to tease out secrets of how life began on Earth 1/22 European Space Agency's Rosetta mission Image of Comet 67P/CG taken by the Philae lander from a distance of approximately 3km from the surface 2/22 European Space Agency's Rosetta mission Rosetta's lander Philae took this parting shot of its mothership shortly after separation 3/22 European Space Agency's Rosetta mission Parting shot of the Philae lander after separation, captured by one of Rosetta's cameras 4/22 European Space Agency's Rosetta mission A technician celebrates after the successful landing of the Philae lander, in the control room at the ESA headquarters in Darmstadt Reuters 5/22 European Space Agency's Rosetta mission Scientists celebrate at a mission observation centre in Toulouse, southern France as they receive information that Philae has landed on the Churyumov-Gerasimenko comet AP 6/22 European Space Agency's Rosetta mission Astronomer Klim Ivanovych Churyumov, who discovered the comet 67P/ Churyumov-Gerasimenko in 1969, reacts after the successful landing of the Philae lander on the comet Reuters 7/22 European Space Agency's Rosetta mission A model demonstrates how the landing device Philae, of the space probe Rosetta, stands on the comet 67P/Churyumov-Gerasimenko at the press center of the satellite control center of the European Space Agency in Darmstadt, Germany EPA 8/22 European Space Agency's Rosetta mission An artist impression of Rosetta's lander Philae on the surface of comet Getty Images 9/22 European Space Agency's Rosetta mission Picture taken on October 28 by the navigation camera on Rosetta shows the boulder-strewn neck region of comet 67/P Churyumov-Gerasimenko. It was captured from a distance of 9.7 km from the center of the comet Getty Images 10/22 European Space Agency's Rosetta mission Picture taken on October 24 shows a raised plateau on the larger lobe of the comet Getty Images 11/22 European Space Agency's Rosetta mission The probe is supposed to fly to a comet and put down a small laboratory on the top of it 12/22 European Space Agency's Rosetta mission A scientist from the European Space Agency with an airworthy copy of space probe 'Rosetta' in the control center in Darmstadt, Germany 13/22 European Space Agency's Rosetta mission Maneuvers designed for the actual space probe are simulated with the replica. 'Rosetta' will be woken up from an energy saving hibernation after 957 days 14/22 European Space Agency's Rosetta mission A European Space Agency employee sits in the control room for the Rosetta mission in Darmstadt, Germany 15/22 European Space Agency's Rosetta mission Scientists at the European Space Agency are expecting their comet-chasing probe Rosetta to wake from almost three years of hibernation 16/22 European Space Agency's Rosetta mission Europe's Rosetta probe on a NASA mission 17/22 European Space Agency's Rosetta mission NASA is participating in the European Space Agency's Rosetta mission, whose goal is to observe one such space-bound icy dirt ball from up close for months on end 18/22 European Space Agency's Rosetta mission An impression of the Philae lander 19/22 European Space Agency's Rosetta mission ESA probe Rosetta with Mars in the background. The three-tonne probe blasted off aboard an an Ariane V rocket from Kourou, French Guiana in 2004 20/22 European Space Agency's Rosetta mission Rosetta orbiter deploying the Philae lander to comet 67P/Churyumov–Gerasimenko, the spacecraft measures 32 m across including the solar arrays, while the comet nucleus is thought to be about 4 km wide 21/22 European Space Agency's Rosetta mission The spacecraft, festooned with 25 instruments between its lander and orbiter (including three from NASA), is programmed to 'wake up' from hibernation 22/22 European Space Agency's Rosetta mission An Ariane V carrying the three-tonne probe Rosetta blasting off from Kourou, beginning a decade-long quest to hunt a comet in the depths of the Solar System and shadow it around the Sun in a bid to tease out secrets of how life began on Earth

Rosetta started its “collision manoeuvre” at 9.50pm UK time on Thursday. From that point, its course was set – there was no turning back for Rosetta on its way down to the rock’s surface.

The spacecraft was due to fly towards the comet and hit the ground at 11.40am UK time on Friday. But it took around 40 minutes for confirmation of that, because of the time it takes for the radio signals to get back to Earth.

The worry for those behind the mission was that there would not be enough time for all of the useful information to be communicated back to Earth before the craft was destroyed.

Scientists decided to crash the craft because the comet is now getting so far away from the sun that the solar panels will not be able to generate enough power to keep it functioning. But by crashing it, they hope to get some last glimpses of the comet – taking what are expected to be stunning images and important data as it heads towards the surface.

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The European Space Agency will share those pictures starting on 30 September, through its special picture page and on its social media channels.

Rosetta arrived at its comet – known as 67P/Churyumov-Gerasimenko – in August 2014, after a 10-year journey. Three months later it dropped a lander called Philae onto the surface, which had been sending back information until scientists lost contact with it – and then found it again, earlier this month.</s>– The Rosetta spacecraft's high-resolution camera took this image of the Philae lander on September 2, 2016. The lander is wedged into a dark crack on a comet, named 67P/Churyumov--Gerasimenko, hurtling through space. The discovery comes less than a month before the Rosetta mission's end.

Philae is wedged in a dark corner of Rosetta – "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. She was the first person to see the images when they were downlinked from the Rosetta probe, according to the European Space Agency.

– The image is detailed enough that viewers can pick out features of Philae's 3-foot-wide (1 meter) body. Even two of its three legs can be seen.

This image of Comet 67P/Churyumov-Gerasimenko was taken by Rosetta on July 8, 2015 as the spacecraft and comet headed toward their closest approach to the sun. Rosetta was about 125 miles (201 kilometers) from the comet when it took this image.

Philae wakes up! Mission managers posted this cartoon of the lander yawning after it came out of hibernation on June 13, 2015. They also sent a series of tweets between the lander and its mothership, Rosetta.

Comet 67P/Churyumov-Gerasimenko is a Jupiter-family comet. Its 6.5 year journey around the Sun takes it from just beyond the orbit of Jupiter at its most distant, to between the orbits of Earth and Mars at its closest. The comet hails from the Kuiper Belt, but gravitational perturbations knocked it towards the Sun where interactions with Jupiter's gravity set it on its present-day orbit.

The Rosetta Mission is tracking Comet 67P/Churyumov-Gerasimenko on its orbit around the sun. This image was taken on May 3, 2015 at a distance of about 84 miles (135 km) from the comet's center.

A camera on Rosetta took this picture of Comet 67P/Churyumov-Gerasimenko on November 22, 2014, from a distance of about 19 miles (31 kilometers). The nucleus is deliberately overexposed to reveal jets of material spewing from the comet. The 2.5-mile-wide (4-kilometer) comet has shown a big increase in the amount of water its releasing, according to NASA. The space agency says about 40 ounces (1.2 liters) of water was being sprayed into space every second at the end of August 2014.

The Rosetta spacecraft's Philae lander is shown sitting on Comet 67P/Churyumov-Gerasimenko after becoming the first space probe to land on a comet on November 12, 2014. The probe's harpoons failed to fire, and Philae bounced a few times. The lander was able to send back images and data for 57 hours before losing power.

Philae snapped these images after landing, and mission scientists used them to create a panoramic view of the landing site. A graphic shows where the probe would be sitting in the photograph.

The image of Comet 67P/Churyumov-Gerasimenko was taken by a camera on the Philae lander during its descent to the comet on November 12, 2014. The lander was about 1.9 miles (3 kilometers) from the surface at the time. Philae touched down on the comet about seven hours later.

The spacecraft sent this image as it approached the comet on August 6, 2014. From a distance of nearly 81 miles (130 kilometers), it reveals detail of the smooth region on the comet's "body" section.

The comet's "head" can be seen in the left of the frame as it casts a shadow over the "body" in this image released August 6, 2014.

Rosetta is named after the Rosetta Stone, the black basalt that provided the key to deciphering Egyptian hieroglyphs. Scientists think the mission will give them new clues about the origins of the solar system and life on Earth. The mission is spearheaded by the European Space Agency with key support from NASA.

This image was taken by an instrument on Rosetta's Philae lander just minutes before the spacecraft made its closest approach to Mars. Part of Rosetta and its solar arrays are visible.

Look closely at the top of this picture. See that dot? That's Saturn. Rosetta snapped the picture of asteroid Lutetia and captured Saturn in the background.

After taking pictures of Earth, Mars and asteroids, Rosetta was put into hibernation in May 2011 after it reached the outer part of the solar system. Mission managers woke it January 20, 2014.</s>(CNN) Here's the challenge: Land a spacecraft that was designed to be an orbiter on the surface of a speeding comet that is millions of miles away and carry out pioneering science on the way down.

It's difficult -- but the Rosetta mission has continued to surprise and delight those who have followed its epic 12-year, comet-chasing journey.

Mission controllers from the European Space Agency (ESA), which is leading the Rosetta mission consortium, are aiming to find out more about the lumpy structures they are calling "goosebumps."

Collected in the wall of pits on the comet's surface, scientists believe they may be the original pieces of material that bonded together to form the body and date to when the solar system was young.

After taking pictures of Earth, Mars and asteroids, Rosetta was put into hibernation in May 2011 after it reached the outer part of the solar system. Mission managers woke it January 20, 2014.

After taking pictures of Earth, Mars and asteroids, Rosetta was put into hibernation in May 2011 after it reached the outer part of the solar system. Mission managers woke it January 20, 2014.

Look closely at the top of this picture. See that dot? That's Saturn. Rosetta snapped the picture of asteroid Lutetia and captured Saturn in the background.

Look closely at the top of this picture. See that dot? That's Saturn. Rosetta snapped the picture of asteroid Lutetia and captured Saturn in the background.

On July 10, 2010, Rosetta flew about 1,864 miles from asteroid Lutetia, which is 10 times larger than asteroid Steins.

On July 10, 2010, Rosetta flew about 1,864 miles from asteroid Lutetia, which is 10 times larger than asteroid Steins.

This image was taken by an instrument on Rosetta's Philae lander just minutes before the spacecraft made its closest approach to Mars. Part of Rosetta and its solar arrays are visible.

This image was taken by an instrument on Rosetta's Philae lander just minutes before the spacecraft made its closest approach to Mars. Part of Rosetta and its solar arrays are visible.

Rosetta took this image of Mars as it looped through the solar system.

Rosetta took this image of Mars as it looped through the solar system.

Rosetta passed asteroid Steins in September 2008, giving scientists amazing close-ups of the asteroid's huge crater. The asteroid is about 3 miles in diameter.

Rosetta passed asteroid Steins in September 2008, giving scientists amazing close-ups of the asteroid's huge crater. The asteroid is about 3 miles in diameter.

Rosetta snapped this image of Earth in November 2009. The spacecraft was 393,328 miles from Earth.

Rosetta snapped this image of Earth in November 2009. The spacecraft was 393,328 miles from Earth.

After its closest approach to Earth in November 2007, Rosetta captured this image of the planet.

After its closest approach to Earth in November 2007, Rosetta captured this image of the planet.

Rosetta has massive solar wings to power the spacecraft. They were unfurled and checked out at the European Space Agency's test facilities before being packed up for liftoff.

Rosetta has massive solar wings to power the spacecraft. They were unfurled and checked out at the European Space Agency's test facilities before being packed up for liftoff.

This photo shows Rosetta being tested before it was wrapped in insulating blankets and loaded on a rocket for launch.

This photo shows Rosetta being tested before it was wrapped in insulating blankets and loaded on a rocket for launch.

Rosetta is named after the Rosetta Stone, the black basalt that provided the key to deciphering Egyptian hieroglyphs. Scientists think the mission will give them new clues about the origins of the solar system and life on Earth. The mission is spearheaded by the European Space Agency with key support from NASA.

Rosetta is named after the Rosetta Stone, the black basalt that provided the key to deciphering Egyptian hieroglyphs. Scientists think the mission will give them new clues about the origins of the solar system and life on Earth. The mission is spearheaded by the European Space Agency with key support from NASA.

Rosetta's mission started on March 2, 2004, when it was launched on a European Ariane 5 rocket from Kourou, French Guiana.

Rosetta's mission started on March 2, 2004, when it was launched on a European Ariane 5 rocket from Kourou, French Guiana.

This image of the comet was taken on August 1, 2014, as Rosetta closed in its target.

This image of the comet was taken on August 1, 2014, as Rosetta closed in its target.

The comet's "head" can be seen in the left of the frame as it casts a shadow over the "body" in this image released August 6, 2014.

The comet's "head" can be seen in the left of the frame as it casts a shadow over the "body" in this image released August 6, 2014.

This image, captured August 7, 2014, shows the diversity of surface structures on the comet's nucleus.

This image, captured August 7, 2014, shows the diversity of surface structures on the comet's nucleus.

The spacecraft sent this image as it approached the comet on August 6, 2014. From a distance of nearly 81 miles (130 kilometers), it reveals detail of the smooth region on the comet's "body" section.

The spacecraft sent this image as it approached the comet on August 6, 2014. From a distance of nearly 81 miles (130 kilometers), it reveals detail of the smooth region on the comet's "body" section.

Rosetta took this image of comet 67P/Churyumov-Gerasimenko on September 15, 2014. The box on the right shows where the lander was expected to touch down.

Rosetta took this image of comet 67P/Churyumov-Gerasimenko on September 15, 2014. The box on the right shows where the lander was expected to touch down.

This mosaic is made of four individual images taken about 20 miles (31.8 kilometers ) from the center of the comet on November 4, 2014.

This mosaic is made of four individual images taken about 20 miles (31.8 kilometers ) from the center of the comet on November 4, 2014.

Rosetta's lander Philae took this parting shot of its mother ship shortly after separation on November 12, 2014, as Philae headed for a landing on Comet 67P. While Philae is the first probe to land on a comet , Rosetta is the first to rendezvous with a comet and follow it around the sun.

The image of Comet 67P/Churyumov-Gerasimenko was taken by a camera on the Philae lander during its descent to the comet on November 12, 2014. The lander was about 1.9 miles (3 kilometers) from the surface at the time. Philae touched down on the comet about seven hours later.

The image of Comet 67P/Churyumov-Gerasimenko was taken by a camera on the Philae lander during its descent to the comet on November 12, 2014. The lander was about 1.9 miles (3 kilometers) from the surface at the time. Philae touched down on the comet about seven hours later.

Philae snapped these images after landing, and mission scientists used them to create a panoramic view of the landing site. A graphic shows where the probe would be sitting in the photograph.

Philae snapped these images after landing, and mission scientists used them to create a panoramic view of the landing site. A graphic shows where the probe would be sitting in the photograph.

Rosetta's lander, Philae, wasn't able to get a good grip on the comet after it touched down. This mosaic shows Philae's movements as it bounced across the comet.

Rosetta's lander, Philae, wasn't able to get a good grip on the comet after it touched down. This mosaic shows Philae's movements as it bounced across the comet.

The Rosetta spacecraft's Philae lander is shown sitting on Comet 67P/Churyumov-Gerasimenko after becoming the first space probe to land on a comet on November 12, 2014. The probe's harpoons failed to fire, and Philae bounced a few times. The lander was able to send back images and data for 57 hours before losing power.

The Rosetta spacecraft's Philae lander is shown sitting on Comet 67P/Churyumov-Gerasimenko after becoming the first space probe to land on a comet on November 12, 2014. The probe's harpoons failed to fire, and Philae bounced a few times. The lander was able to send back images and data for 57 hours before losing power.

Rosetta took this picture of a section of the comet's two lobes from a distance of about 5 miles (8 kilometers) on October 14, 2014.

Rosetta took this picture of a section of the comet's two lobes from a distance of about 5 miles (8 kilometers) on October 14, 2014.

A camera on Rosetta took this picture of Comet 67P/Churyumov-Gerasimenko on November 22, 2014, from a distance of about 19 miles (31 kilometers). The nucleus is deliberately overexposed to reveal jets of material spewing from the comet. The 2.5-mile-wide (4-kilometer) comet has shown a big increase in the amount of water its releasing, according to NASA. The space agency says about 40 ounces (1.2 liters) of water was being sprayed into space every second at the end of August 2014.

A camera on Rosetta took this picture of Comet 67P/Churyumov-Gerasimenko on November 22, 2014, from a distance of about 19 miles (31 kilometers). The nucleus is deliberately overexposed to reveal jets of material spewing from the comet. The 2.5-mile-wide (4-kilometer) comet has shown a big increase in the amount of water its releasing, according to NASA. The space agency says about 40 ounces (1.2 liters) of water was being sprayed into space every second at the end of August 2014.

Rosetta snapped this wide-angle view of Comet 67P/Churyumov-Gerasimenko in September 2014. Rosetta was about 107 million miles (172 million kilometers) from Earth and about 92 million miles (148 million kilometers) from the sun when the photo was released.

Rosetta snapped this wide-angle view of Comet 67P/Churyumov-Gerasimenko in September 2014. Rosetta was about 107 million miles (172 million kilometers) from Earth and about 92 million miles (148 million kilometers) from the sun when the photo was released.

This image of Comet 67P/Churyumov-Gerasimenko was taken on April 15, 2015.

This image of Comet 67P/Churyumov-Gerasimenko was taken on April 15, 2015.

The Rosetta Mission is tracking Comet 67P/Churyumov-Gerasimenko on its orbit around the sun. This image was taken on May 3, 2015 at a distance of about 84 miles (135 km) from the comet's center.

The Rosetta Mission is tracking Comet 67P/Churyumov-Gerasimenko on its orbit around the sun. This image was taken on May 3, 2015 at a distance of about 84 miles (135 km) from the comet's center.

Rosetta's navigation camera took this image of the comet on June 1, 2015.

Rosetta's navigation camera took this image of the comet on June 1, 2015.

This image of Comet 67P/Churyumov-Gerasimenko was taken by Rosetta on June 5, 2015, while the spacecraft was about 129 miles (208 kilometers) from the comet's center.

This image of Comet 67P/Churyumov-Gerasimenko was taken by Rosetta on June 5, 2015, while the spacecraft was about 129 miles (208 kilometers) from the comet's center.

Comet 67P/Churyumov-Gerasimenko is a Jupiter-family comet. Its 6.5 year journey around the Sun takes it from just beyond the orbit of Jupiter at its most distant, to between the orbits of Earth and Mars at its closest. The comet hails from the Kuiper Belt, but gravitational perturbations knocked it towards the Sun where interactions with Jupiter's gravity set it on its present-day orbit.

Comet 67P/Churyumov-Gerasimenko is a Jupiter-family comet. Its 6.5 year journey around the Sun takes it from just beyond the orbit of Jupiter at its most distant, to between the orbits of Earth and Mars at its closest. The comet hails from the Kuiper Belt, but gravitational perturbations knocked it towards the Sun where interactions with Jupiter's gravity set it on its present-day orbit.

Philae wakes up! Mission managers posted this cartoon of the lander yawning after it came out of hibernation on June 13, 2015. They also sent a series of tweets between the lander and its mothership, Rosetta.

Philae wakes up! Mission managers posted this cartoon of the lander yawning after it came out of hibernation on June 13, 2015. They also sent a series of tweets between the lander and its mothership, Rosetta.

This image of Comet 67P/Churyumov-Gerasimenko was taken by Rosetta on July 8, 2015 as the spacecraft and comet headed toward their closest approach to the sun. Rosetta was about 125 miles (201 kilometers) from the comet when it took this image.

This image of Comet 67P/Churyumov-Gerasimenko was taken by Rosetta on July 8, 2015 as the spacecraft and comet headed toward their closest approach to the sun. Rosetta was about 125 miles (201 kilometers) from the comet when it took this image.

The Rosetta spacecraft captured this image of a jet of white debris spraying from Comet 67P/Churyumov--Gerasimenko on July 29, 2015. Mission scientists said this was the brightest jet seen to date in the mission. The debris is mostly of ice coated with dark organic material.

One of the primary objectives of the Rosetta mission was to drop the Philae lander onto the comet. The probe was successfully deployed in November 2014, becoming the first probe to land on a comet. But Philae failed to grab onto the comet and bounced around. It fell silent a few days later. Then on June 13, 2015, Philae came out of hibernation and "spoke" to mission managers at the European Space Agency for 85 seconds. This photo above was taken by the lander's mothership, the Rosetta orbiter, after the lander started its descent to the comet.

The image is detailed enough that viewers can pick out features of Philae's 3-foot-wide (1 meter) body. Even two of its three legs can be seen.

Philae found using images from Rosetta – The image is detailed enough that viewers can pick out features of Philae's 3-foot-wide (1 meter) body. Even two of its three legs can be seen.

"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. She was the first person to see the images when they were downlinked from the Rosetta probe, according to the European Space Agency.

Philae is wedged in a dark corner of Rosetta – "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. She was the first person to see the images when they were downlinked from the Rosetta probe, according to the European Space Agency.

The Rosetta spacecraft's high-resolution camera took this image of the Philae lander on September 2, 2016. The lander is wedged into a dark crack on a comet, named 67P/Churyumov--Gerasimenko, hurtling through space. The discovery comes less than a month before the Rosetta mission's end.

Philae has been found! – The Rosetta spacecraft's high-resolution camera took this image of the Philae lander on September 2, 2016. The lander is wedged into a dark crack on a comet, named 67P/Churyumov--Gerasimenko, hurtling through space. The discovery comes less than a month before the Rosetta mission's end.

ESA describes the latest phase as the "biggest challenge yet" as it tries to maneuver the orbiter into position for the descent and impact on the comet on September 30.

The agency says Rosetta will try to gather images and other data on the gas, dust and plasma very close to the comet.

Rosetta has already returned spectacular images and science discoveries from Comet 67P/Churyumov--Gerasimenko as it followed its orbit around the sun.

And millions followed the drama when the landing craft Philae separated from Rosetta and bounced across the comet after its thruster and grappling harpoons designed to anchor it to the surface failed in November 2014. The accident proved to be something of a blessing though as Philae was able to carry out some of its objectives in two locations.

The instruments discovered 16 organic compounds, including four that had been never detected on comets, before Philae's batteries drained. Scientists were excited by the results because some of those chemicals form the building blocks of the ingredients for life.

Mission controllers believed Philae was trapped under a cliff but were unable to find exactly where it ended up after going silent in its resting place.

Then just weeks ago Philae returned from the cosmic dead when scientists had a stroke of luck. After months of searching they discovered the probe with their last opportunity to photograph from Rosetta a possible location for the craft.

It's important too because as lander system engineer Laurence O'Rourke explained, they now have "perfect contextual data" for the measurements Philae made.

"It couldn't have been in a more difficult location -- quite literally between a rock and a hard place," he told CNN.

But the engineer said he was thrilled to find out the fate of Philae after working on the campaign for so long.

"It was like drinking a gallon of adrenaline," O'Rourke said. "I was astounded by the quality of the picture. It was magnificent."

Now mission controllers are preparing for the last act at 67P.

"We are not trying to gain science from hitting the comet," said O'Rourke. "We are trying to gain science before we hit it.

"This is a controlled descent and impact."

Now that the comet and the orbiter have traveled so far away from the sun there will come a point where there isn't enough solar power to run the heaters and computers.

O'Rourke told CNN that as the probe would die anyway the decision was made to try to capture more data including very high resolution images of the pit structures.

"We don't have enough power to keep it alive. We wanted to take control of the end," he said.

The engineer said he would miss the mission, especially the public enthusiasm for Rosetta but added: "The legacy will be there for many generations."

Astronomer Dan Brown, who lectures at Nottingham Trent University in the UK, said the Rosetta mission had been an "astonishing" engineering feat but also inspirational.

"The Rosetta mission has helped us gain an insight into the activity of comets, how comets were created and to some extent if they could have been the source for water on our early Earth," he told CNN.

"The presence of complex molecules, some of which previously unknown to exist on comets, still allows comets to be a possible source of introducing complex molecules and enable the formation of life on Earth.

"The image that does it for me is seeing the surface of the comet and the lander together. Such imagery inspires as much as the Moon landings and drives us to go and discover, achieve and face challenges on our never-ending quest for knowledge."

The end of the mission also brings to a close the Twitter chat that has endeared followers to Rosetta and Philae, and their surreal and strangely touching conversations, especially when the landing craft bounced and disappeared.

Asked if he would change anything, O'Rourke said: "Philae couldn't have been designed better than it was ... but I think I would have added LEDs that flash so it could have been detected wherever it landed."</s>BERLIN -- After 12 years of hurtling through space in pursuit of a comet, the Rosetta probe ended its mission Friday with a slow-motion crash onto the icy surface of the alien world it was sent out to study.

Mission controllers lost contact with the probe, as expected, after it hit the surface of comet 67P/Churyumov-Gerasimenko at 5:39 a.m. Central time Friday, the European Space Agency said.

"Farewell Rosetta, you've done the job," said mission manager Patrick Martin. "That is space science at its best."

Agency chief Jan Woerner called the $1.57 billion mission a success. Aside from sending a lander onto the surface of comet 67P in November 2014 -- a cosmic first -- the Rosetta mission has collected vast amounts of data that researchers will spend many years analyzing.

Scientists have already heralded several discoveries from the mission that offer new insights into the formation of the solar system and the origins of life on Earth.

Spectacular images taken by the orbiter and its comet lander revealed a desert-like landscape on the comet with wide, featureless regions but also high cliffs and sinkholes that were more than a hundred yards across.

The shape of 67P itself -- two orbs connected by a "neck" that have been likened to a giant rubber duck -- surprised scientists when Rosetta first got up close. Researchers now believe the orbs formed independently and later merged into one.

Jessica Sunshine, a senior scientist on NASA's Deep Impact and Stardust comet missions, said the way the comet was formed has implications for the model of how other objects in the solar system, including Earth, formed about 4.5 billion years ago.

Scientists were also surprised to find that the surface of 67P is changing, not just due to steady erosion as particles are released into the void, but also from sudden large events such as landslides.

"We see evidence of mass movement of materials on this comet," said Sunshine, who wasn't directly involved in the Rosetta mission. "That's nothing like what we imagined."

One of the crucial differences between Rosetta and previous missions was the probe's ability to study one comet for an extended period of time. While Deep Impact fired a projectile into comet Tempel 1 back in 2005 and studied the crater for 15 minutes, Rosetta spent 786 days flying alongside 67P, observing its evolution across several "seasons" as it raced toward and then away from the sun.

"Rosetta is what I would call a Cadillac mission that had all the right instruments and stayed reasonably close to the comet since fall 2014," said Mike A'Hearn, an emeritus professor at the University of Maryland who worked on the Rosetta mission.

"It's the first detailed study of a comet," he said. "We have collected a wealth of data that has come in so fast we haven't even had a chance to look at some of it, let alone analyze it properly."

Data from the probe also has challenged some existing scientific theories, such as those about the origins of water on Earth and how best to hunt for extraterrestrial life.

"Rosetta has blown it all open," said Matt Taylor, the mission's project scientist. "It's made us have to change our ideas of what comets are, where they came from and the implications for how the solar system formed and how we got to where we are today."

Scientists decided to crash-land the probe on the comet because Rosetta's solar panels would not have been able to collect enough energy as it flew away from the Sun along 67P's elliptical orbit.

After receiving its final command late Thursday, Rosetta fired its thrusters for 208 seconds and performed a last series of scientific measurements as it swooped toward the surface of the 2.5-mile wide comet.

Because of the vast distance between the comet and Earth -- almost 447 million miles -- confirmation of the probe's crash took about 40 minutes to reach mission control in Darmstadt, Germany.

The controlled descent took place at about one yard per second-- roughly half of walking speed. That gave Rosetta a chance to snap some unprecedented low-altitude images of the comet that could reveal surface features as small as a grape.

Fans of the mission -- which was promoted heavily with cartoons, short films, music and social media -- may be disappointed to learn there's no chance of a Rosetta revival when the comet itself swings back toward the sun.

"It will not be possible to reactivate it again," said ESA's head of mission operations, Paolo Ferri. "We wanted a clean end."

Still, Rosetta guards one last message. On board is a small metal plate with texts etched in more than 1,000 languages.</s>BERLIN (AP) — Europe's comet-chasing space probe Rosetta performed its final task Friday, dipping out of orbit for a slow-motion crash onto the icy surface of the alien world it's been following for more than a decade.

Mission controllers lost contact with the probe as expected after it hit the surface of comet 67P/Churyumov-Gerasimenko, marking the planned end of a 12-year mission, the European Space Agency said.

"Farewell Rosettta, you've done the job," said mission manager Patrick Martin. "That is space science at its best."

Scientists sent their final command to the probe late Thursday, ordering Rosetta to fire its thrusters for 208 seconds and perform a last series of scientific measurements as it swooped toward the surface of the 4-kilometer-wide (2.5 miles) comet.

Because of the distance between the comet and Earth, confirmation of the impact at 1039 GMT took about 40 minutes to reach ESA's mission control in Darmstadt, Germany.

Jan Woerner, the head of the European Space Agency, said the 1.4 billion euro ($1.57 billion) mission was already a success. Aside from sending a lander onto the surface of comet 67P in November 2014 — a cosmic first — the Rosetta mission has collected vast amounts of data that researchers will spend many more years analyzing.

Scientists have already heralded a number of discoveries about the chemical composition of the comet that provide crucial insights into the formation of the solar system and theories about the origin of life on Earth.

The controlled descent took place at about 90 centimeters per second — roughly half walking speed — giving Rosetta a chance to snap some unprecedented low-altitude images of the comet that could reveal surface features as small as an inch (2.5 centimeters).

Andrea Accomazzo, the spacecraft operations manager, said the mission had been a huge challenge and should be considered an achievement "not just for ESA, but for mankind." Should Earth ever be threatened by an asteroid, the experience gained from the Rosetta mission would prove valuable, he said.</s>The Rosetta spacecraft has crash landed onto the surface of the distant comet it has been exploring for the past two years.

European Space Agency (Esa) controllers burst into applause when the crunch ending to the £1 billion mission was confirmed at 12.20pm, UK time.

Rosetta had already been lying in its lonely resting place 485 million miles away on comet 67P/Churyumov-Gerasimenko for nearly an hour, because of the 40 minutes it took for radio signals travel to Earth.

A decision was taken to carry out the “controlled impact” because the comet is taking Rosetta so far from the Sun that soon its solar panels will not be able to generate sufficient power.

The spacecraft came down in the rugged Ma’at region of the comet, which is littered with boulders and deep active pits known to produce jets of gas and dust.

Despite travelling at just 1.1mph the craft was not designed for landing and had no chance of survival.

Esa’s head of mission operations Paolo Ferri said: “I think everybody’s very sad. On the other hand the end of the mission had to come. It was a spectacular way to do it, and we’re quite convinced it was the right thing to do.”

Scientists chose to crash Rosetta on the smaller of the three-mile-long rubber duck-shaped comet’s two lobes, just a few kilometres from where its tiny lander Philae is lodged in a deep crevice.

Rosetta reached comet 67P/Churyumov-Gerasimenko on August 6, 2014, after an epic 10-year journey across four billion miles of space.

The spacecraft and its lander, which bounced onto the surface of the comet on November, 2014, have produced a wealth of data providing valuable clues about the origins of the solar system and life on Earth.

Key discoveries include an unusual form of water not common on Earth and carbon-containing organic molecules that are the building blocks of life.

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DOWNLOAD THE SCOTSMAN APP ON ITUNES OR GOOGLE PLAY</s>The European Space Agency’s most ambitious mission yet has come to an end as the Rosetta spacecraft collided with the comet’s surface today.

Some space missions go out with a bang, others with a victorious return to Earth, but Rosetta’s final moment was marked simply by radio silence.

After twelve-and-a-half years in space, the European Space Agency spacecraft finally met the surface of the duck-shaped mass of dust, ice and rock, switched off its transmitters and hung up the phone to its controllers on Earth.

Patrick Martin, Rosetta’s mission manager, said: “This is the culmination of tremendous scientific and technical success for this mission. It was historic, it was pioneering and it is revolutionising how we see comets. Farewell Rosetta, you’ve done the job, that was space science at its best.”

Scientists faced a nail-biting 40 minute wait for confirmation that it had touched down and to see the last images captured by Rosetta, taken around 15 metres from the comet’s surface.

The spacecraft touched down on the “head” of the comet at a speed of about 90 centimetres per second - around a walking pace. Mission scientists described this as a “controlled descent” rather than a crash.

Although the surface is soft - something akin to the texture of a soft snow-drift - the lander is likely to get damaged in the collision and could even bounce off the surface, as the Philae lander did. Even if its solar panels and other hardware remain intact, the craft has been pre-programmed to shut down its systems on contact, marking the end of a mission that has gripped the world.

Its precise fate will never be known, because Rosetta is now switched off for good and there are no telescopes on Earth powerful enough to see it.

“We won’t know, because we turn off when we touch the surface,” said Professor Mark McCaughrean, a senior science advisor at ESA. “This is space, anything can happen out there ... It’s a bit like does a tree make a sound in the forest if no one is there to hear it?”

Ahead of the landing, the flight team estimated that the craft would impact just 40 metres away from their original target on the Ma’at region of the head, which marked by large pits and “goose bump” structures.

The last images sent back may look like dust-covered rocks, but measurements sent back from Rosetta show that the comet is extremely porous - about 70% of its interior is empty space.



“When you see these beautiful images of the comet you should not think of it as rock,” said Björn Davidsson, a Rosetta scientist based at Nasa’s jet propulsion laboratory. “It’s something like spun sugar or cotton candy – something very, very fluffy.”

Rosetta arrived at 67P/Churyumov-Gerasimenko in August 2014, after spending a decade chasing down the comet.

In the two years since, it has sent back spectacular photographs of the comet’s dramatic landscapes as well as reams of scientific data measuring its composition, density and magnetic field.

In terms of sheer drama, the mission’s climax came when a small robotic probe, Philae, was dispatched onto the comet’s surface in November 2014 to gather surface samples.

Comet 67P is now heading out towards the orbit of Jupiter, and as it speeds away from the sun, Rosetta’s solar power supply was set to run out.



Matt Taylor, ESA Rosetta project scientist, said that rather than hobbling on in a sub-optimal state, the team decided to commit to some final close-up observations. “I’ve seen certain rock bands with certain singers that can’t sing anymore. They should have stopped when they were fully functioning,” he said, ahead of the mission’s end. “And that is what we are doing here with Rosetta. It is maximising what we can do with the spacecraft at this time. This plunge is the only way to get this science.”

These are thought to be the original icy boulders that formed in the solar system more than four billion years ago and then came together to form this comet. In short, the goose bumps are some of the most ancient unaltered objects from the beginning of the solar system. They contain all the ingredients that were available to form life on Earth.

McCaughrean 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.”</s>BERLIN – After 12 years of hurtling through space in pursuit of a comet, the Rosetta probe ended its mission Friday with a slow-motion crash onto the icy surface of the alien world it was sent out to study.

Mission controllers lost contact with the probe, as expected, after it hit the surface of comet 67P/Churyumov-Gerasimenko at 6:39 a.m. Friday, the European Space Agency said.

“Farewell Rosetta, you’ve done the job,” said mission manager Patrick Martin. “That is space science at its best.”

ESA chief Jan Woerner called the $1.57 billion mission a success. Aside from sending a lander onto the surface of comet 67P in November 2014 – a cosmic first – the Rosetta mission has collected vast amounts of data that researchers will spend many years analyzing.

Scientists have already heralded several discoveries from the mission that offer new insights into the formation of the solar system and the origins of life on Earth.

Spectacular images taken by the orbiter and its comet lander revealed a desert-like landscape on the comet with wide, featureless regions but also high cliffs and sinkholes that were more than 110 yards across.

The shape of 67P itself – two orbs connected by a “neck” that have been likened to a giant rubber duck – surprised scientists when Rosetta first got up close. Researchers now believe the orbs formed independently and later merged into one.

Jessica Sunshine, a senior scientist on NASA’s Deep Impact and Stardust comet missions, said the way the comet was formed has implications for the model of how other objects in the solar system, including Earth, formed about 4.5 billion years ago.

Scientists were also surprised to find that the surface of 67P is changing, not just due to steady erosion as particles are released into the void, but also from sudden large events such as landslides.

“We see evidence of mass movement of materials on this comet,” said Sunshine, who wasn’t directly involved in the Rosetta mission. “That’s nothing like what we imagined.”

One of the crucial differences between Rosetta and previous missions was the probe’s ability to study one comet for an extended period of time. While Deep Impact fired a projectile into comet Tempel 1 back in 2005 and studied the crater for 15 minutes, Rosetta spent 786 days flying alongside 67P, observing its evolution across several “seasons” as it raced toward and then away from the Sun.

“Rosetta is what I would call a Cadillac mission that had all the right instruments and stayed reasonably close to the comet since fall 2014,” said Mike A’Hearn, an emeritus professor at the University of Maryland who worked on the Rosetta mission.

“It’s the first detailed study of a comet,” he said. “We have collected a wealth of data that has come in so fast we haven’t even had a chance to look at some of it, let alone analyze it properly.”

Data from the probe has also challenged some existing scientific theories, such as those about the origins of water on Earth and how best to hunt for extraterrestrial life.</s>“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.

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.”

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.

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.”</s>During its final descent, Rosetta will gather close-range information about the comet and hastily beam data back to Earth before its main transmitter shuts off for good.

It was conceived when Ronald Reagan was in the White House. It launched a few weeks after Mark Zuckerberg created Facebook in his Harvard dorm. It spent a full decade looping around the solar system. When it finally caught up with its target, it deployed the first probe to land on a speeding comet and survive.

Now the long, dramatic journey of the Rosetta space orbiter is about to end. After logging 4.9 billion miles, the craft is set to fall early Friday to the surface of 67P/Churyumov-Gerasimenko, the mountain-size comet it has been following for the past two years.

But first it has just a bit more science to do.

During its final descent, Rosetta will gather close-range information about the comet and hastily beam data back to Earth before its main transmitter shuts off for good.

“It’s kind of bittersweet,” said Paul Weissman, a comet scientist at the Planetary Science Institute in Tucson, Ariz., who worked on Rosetta for 20 years. “You’d like to keep going, but it is also very satisfying. It’s been a tremendously successful mission.”

The $1 billion mission has been full of suspense.

Its many plot twists began before the spacecraft left Earth, when a faulty rocket postponed the launch by two years and caused mission planners at the European Space Agency (ESA) to abandon their original comet and select a different one.

The new comet, 67P, was four times larger than the initial target, and meeting up with it required a longer flight than originally planned. Between March 2004 and January 2014, Rosetta made three Earth flybys and one close pass by Mars, using the planets’ gravity to give it a boost.

Along the way, it imaged two asteroids and endured a hibernation of two years, seven months and 12 days.

Engineers programmed four alarm clocks to wake the spacecraft from its epic slumber. Everything hinged on its ability to boot back up, said Rosetta Flight Director Andrea Accomazzo.

“Either we had a mission, or we had no mission at all,” he said.

Scientists are fascinated by comets because they believe the mysterious bodies were formed in the earliest days of the solar system, and that frozen into their icy nuclei are the same primordial materials that make up the planets.

As Rosetta closed in on its target, researchers were dazzled by the strange and unexpected shape that gradually came into focus. The comet was roughly 2.5 miles across and had two distinct lobes that resembled a rubber duck with a head, thin neck and bulbous body. In time, Rosetta’s instruments revealed a dramatic world of towering cliffs, deep pits and massive boulders.

“It was a big surprise,” said Claire Vallat, a scientist at the agency’s European Space Astronomy Center.

After officially entering 67P’s orbit on Aug. 6, 2014, Rosetta spent several months mapping the surface to find the best spot to send Philae, its 220-pound washing-machine-size lander. The mission team ultimately selected what the late NASA scientist Claudia Alexander described as “the least-worst option”: a site that got enough sunlight to power Philae’s solar panels and that appeared to have shallower slopes and fewer boulders than other areas.

On Nov. 12, 2014, scientists were once again on the edge of their seats as Philae made a slow, seven-hour descent to the surface of 67P. It was humanity’s first attempt to make a soft landing on a comet.

The unprecedented maneuver did not go exactly as planned. The lander’s harpoons failed to fire, and Philae bounced twice before coming to rest in what remained an unknown location for nearly two years.

It soon became clear that Philae’s solar panels would not receive enough sunlight to keep powering the onboard instruments, so it was able to conduct experiments for only 60 hours before shutting down. But mission scientists insist Philae was no failure.

“Philae sent back quite a bit of information for three days,” said Weissman, of the Planetary Science Institute. “We didn’t learn everything we wanted to from the lander, but we did learn a lot.”

In the meantime, Rosetta continued to orbit the comet as it made its closest approach to the sun in August 2015.

From a safe distance of 186 miles, it watched as 67P became more active, with streams of dust and gas shooting off its surface. The comet’s display subsided as it flew farther from the sun.

“Rosetta had a major goal in mind, which was to rendezvous with a comet far from the sun and watch it wake up and then let it die down again,” said Laurence O’Rourke, a lander-systems engineer at ESA. “Overwhelmingly, we have met that goal.”

The drama was not over. Less than one month before the mission’s end, Rosetta’s cameras finally spotted Philae wedged into a dark crack on the comet’s surface. Two of its legs were sticking up in the air.

Finding Philae after all that time “was like drinking a bottle of adrenaline,” O’Rourke said. “I couldn’t sleep for the whole night.”

Now Rosetta has reached the end of its journey. Comet 67P is on its way toward the orbit of Jupiter, and soon Rosetta’s 100-foot solar panels will be too far from the sun for the spacecraft to function. “Operating Rosetta beyond this point wouldn’t be possible,” Accomazzo said.

Experts say there is no chance the orbiter will survive its Friday collision with the comet.

Although the last few minutes of its life are difficult to predict, researchers expect it to hit 67P at a walking pace of slightly less than 3 feet per second. When it lands, it will tumble and bounce before settling into its final resting place on the small lobe of the comet. The impact will kick up a few clouds of dark, powdery dust. Then a preprogrammed computer command will turn off its transmitters forever.

The final death dive will not be made in vain. The lander will be pointed toward the Ma’at region, which is home to several intriguing pits that released jets of dust when the comet was closer to the sun and more active.

In addition, researchers have spotted lumpy structures on the pit walls that might be cometessimals, the building blocks of the comet. Scientists are eager to get a closer look.

“The plan is to go as low as possible and transmit as late as possible,” Vallat said.

On Earth, meanwhile, hundreds of scientists and engineers will gather at the European Space Operations Center in Darmstadt, Germany, to watch for the flattening of the radio signal that will let them know Rosetta has gone offline forever.
The European Space Agency's Rosetta space probe ends its 12-year mission studying comet 67P/Churyumov–Gerasimenko in a "collision maneuver" into the comet's surface.