The Philae lander from European Space Agency's Rosetta mission's landed on Comet 67P/Churyumov-Gerasimenko.
Credit: ESA - European Space Agency
Credit: ESA - European Space Agency
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TechTranscript
00:00This is the moment we made history by landing on a comet.
00:12Ten years ago, our Rosetta mission got up close and personal with a comet, landing a
00:17probe called Philae on the surface to directly study the properties of a comet for the first
00:24time ever.
00:27The mission was groundbreaking, it was only the seventh celestial object we have landed
00:31on before.
00:34It was an ambitious journey filled with many ups and downs, but we're getting ahead of
00:39ourselves.
00:40Let's take a look back at the mission ten years on.
00:53Comets are large objects made of dust and ice that have elliptical orbits around the
00:57sun, which stretch far out into the outer edges of the solar system.
01:04They are believed to be left over from when the planets formed, and scientists think they
01:08could hold the answers to how life formed on Earth, why we have water on Earth, and
01:14how the solar system evolved.
01:18You may recognise comets from their distinctive bright tail, caused by the sun heating up
01:23the frozen comet's core as they head towards the inner solar system, leaving behind this
01:29bright streak of dust and gas.
01:33Most comets are too small and far away to see from Earth, even with some of the biggest
01:38telescopes, and when they do come close, their bright tail obscures our view of the actual
01:43comet itself, making it hard to see and study from Earth.
01:49That's where our Rosetta mission comes in.
02:00Rosetta was launched in March 2004 on one of our Ariane 5 rockets.
02:06From here, it set off on its 10-year-long journey to Comet 67P Churyumov-Gerasimenko.
02:14The Comet was chosen as it originated in the Kuiper Belt, but does not venture out much
02:19farther than Jupiter anymore, making it perfect to align with Rosetta's journey.
02:25However, the journey was anything but simple.
02:29Rosetta required some energy boosts along the way, starting with a gravity assist of
02:35just a year after launch, which sent the spacecraft on towards Mars for another boost.
02:41From here, Rosetta came back to Earth before passing by the diamond-shaped asteroid Stainez
02:48and returning back to Earth for one final boost.
02:52Rosetta then got on its way to deeper space, flying past the huge ancient rock Laetitia,
02:59grabbing photos and data along the way.
03:02After all of this excitement, as Rosetta travelled on farther from the Sun, it did
03:07not have enough solar power to operate fully, so was put into standby mode, sending the
03:13spacecraft into a two-year, seven-month and 12-day slumber.
03:19In January 2014, the world sent Rosetta a wake-up call, and the team got sent to work
03:25to make sure all the instruments on board were working after the long break.
03:31The spacecraft still had 10 more manoeuvres to perform to align it correctly with the
03:36comet, and to get it to the right speed so it would be captured by the comet's gravity
03:42and not be flung off into space.
03:52As Rosetta approached Comet 67P, scientists spotted something unusual.
03:58The team expected to see that the central part of the comet, its nucleus, is sort of
04:03shaped like a potato, but instead, the images Rosetta sent back resembled more of a rubber
04:09duck shape.
04:10It had two lobes, almost as if the two comets had slammed into each other and bonded.
04:18It looked like nothing we had ever examined in the solar system before.
04:23This made landing Philae a bit more complicated.
04:26The complex shape of the comet made for a complex gravity and a strange rotation situation,
04:34which made flying around it very complicated.
04:37There were also craters, cliffs, sinkholes and boulders the size of houses, which had
04:42to be taken into account.
04:46Rosetta spent a few weeks analysing the comet, sending back information so the experts could
04:51determine where was best to land.
04:53Typically landing sites, for example on Mars, take years to select, so for Philae it happened
05:00exceptionally fast.
05:02No lander had attempted to make a soft landing on a comet before, so there was a lot at stake.
05:09Finally, the experts decided on the perfect landing spot for Philae, and the probe was
05:15sent down, and the world held its breath for seven hours to hear if the spacecraft landed
05:21successfully.
05:24Touchdown was confirmed at 1703 CET on 12 November, but there was something strange
05:32about the data returned.
05:35Soon scientists, flight dynamics specialists and engineers concluded that Philae did not
05:40just touch down once on the comet, but three times.
05:46The harpoons that were meant to dig Philae into the comet's surface securely had not
05:51fired and the lander appeared to be rotating after the first touchdown.
05:56And then the lander lifted from the surface, for one hour and fifty minutes.
06:02During that time it travelled about one kilometre at a speed of 38 centimetres per second.
06:09It then made a smaller second hop, travelling at about three centimetres per second and
06:15landing in its final resting place seven minutes later.
06:21This left Philae in an awkward angle, but it was still able to conduct its on-board
06:25experiments and send data back down to us here on Earth.
06:30However, the landing spot had limited sunlight, meaning the solar panels could not be charged,
06:37and Philae eventually lost power after 57 hours.
06:41In the end, about 80% of the planned science was completed, not bad considering the circumstances.
06:49Meanwhile Rosetta continued to study the environment of the comet, studying the dust particles
06:54which flew off as it became more active on its approach to the Sun, and monitored the
06:59changes on the surface.
07:03After 211 days, Rosetta noticed a strange signal.
07:08It analysed the data and realised Philae had woken up, after seven months in hibernation.
07:15Engineers determined that Philae was exposed to sufficient sunlight to heat it to an acceptable
07:20operating temperature, and to generate electricity.
07:25This allowed for the experts to home in on the final resting place of Philae, and allow
07:30us to say a final goodbye.
07:39After becoming the first spacecraft to orbit a comet, and the first to deploy a lander,
07:44Philae, in November 2014, Rosetta continued to monitor the comet's evolution surviving
07:51the harsh environment of the comet for 786 days, making a few dramatic flybys close to
07:58its surface, surviving several unexpected outbursts from the comet, and recovered from
08:05two spacecraft safe modes.
08:09After almost two years in operation around the comet, and 12 years in space, Rosetta's
08:14own mission would also come to an end on the surface of the comet, with a controlled impact.
08:20Confirmation of the end of the mission arrived at our control centre at 1319 CEST, with the
08:29loss of Rosetta's signal upon impact.
08:33The descent gave Rosetta the opportunity to study the comet right up until its last
08:38moments.
08:39The world may have said goodbye to Rosetta, but its legacy will not be forgotten.
08:45Rosetta changed our view of how the solar system formed, how the planets were made,
08:50and gave a glimpse at how life could have begun here on Earth.