Landing on a Comet: Watch
08-07-2014
, 10:43 AM
First great photos and info
http://www.technologyreview.com/view...comet-landing/
From above link:
Alessandro Ovi
August 6, 2014
European Space Agency Reaches Verge of Breakthrough Comet Landing
Images sent back from space probe bring a historic comet mission into clear focus.
This is no ordinary rock. It’s the surface of a comet somewhere between Jupiter and Mars, and it took a European space probe known as Rosetta 10 years to get there before it sent back these unprecedented images today.
Rosetta took these pictures after a series of maneuvers in which it fired thrusters to position itself less than 100 kilometers above the surface of the comet, known as 67P/Churyumov-Gerasimenko. The crucial next step is expected to come in November, when Rosetta will send down a lander to the surface. Scientists hope the lander’s explorations will yield clues not only about this particular comet, but also about the role such chunks of rock and ice have played in celestial history. In the words of my friend Berndt Feuerbacher, a German scientist who is a former president of the International Astronautical Federation: “Comets are relics from the origin of our solar system, kept in a kind of cosmic deep freeze far beyond the outer planets, unchanged in 4.5 billion years.” They provide “a unique opportunity to learn about how our sun, Earth, planets, and even life began.”
The last seven months have been the most critical time in the €1.3 billion project. Before January, Rosetta had spent almost three years in hibernation: it was almost entirely shut down while it was too far from the Sun to draw enough energy for charging its batteries and keeping its instruments running. It drifted instead with the gravitational pull of the Sun and planets.
On that day in January, it was time to begin maneuvering toward the comet. Inside the European Space Agency’s operations center in Darmstadt, Germany, tension grew at the appointed time for Rosetta’s awakening. The scientists would know it had happened when a flat signal on a green monitor finally showed a peak. But 20 minutes after the scheduled time, there was nothing. Feuerbacher told me that there was a deep silence in the room. The European astronaut Thomas Reiter sent Feuerbacher a text message: “Are we a bit late Berndt?”
“Wait, Thomas, wait,” Feuerbacher says he replied. “It’s so far away and has many things to do before telling us she is awake. Open panels, heat up a bit, point its antenna toward Earth, trying to convey, and maybe it fails at the first attempt.”
When the signal on the screen finally spiked a few minutes later, applause burst through the hall. Operations staff put their fists skyward and hugged each other.
After Rosetta’s lander, known as Philae, plunges to the surface of the comet in November, its biggest challenge will be staying there. A comet has such little gravity that Philae could easily bounce from its surface and back into space. But Philae has an anchor to bite into the comet’s surface—a moment that will have everyone in the Darmstadt center holding their breath again.
__________________________________________________ ______
http://www.technologyreview.com/view...comet-landing/
From above link:
Alessandro Ovi
August 6, 2014
European Space Agency Reaches Verge of Breakthrough Comet Landing
Images sent back from space probe bring a historic comet mission into clear focus.
This is no ordinary rock. It’s the surface of a comet somewhere between Jupiter and Mars, and it took a European space probe known as Rosetta 10 years to get there before it sent back these unprecedented images today.
Rosetta took these pictures after a series of maneuvers in which it fired thrusters to position itself less than 100 kilometers above the surface of the comet, known as 67P/Churyumov-Gerasimenko. The crucial next step is expected to come in November, when Rosetta will send down a lander to the surface. Scientists hope the lander’s explorations will yield clues not only about this particular comet, but also about the role such chunks of rock and ice have played in celestial history. In the words of my friend Berndt Feuerbacher, a German scientist who is a former president of the International Astronautical Federation: “Comets are relics from the origin of our solar system, kept in a kind of cosmic deep freeze far beyond the outer planets, unchanged in 4.5 billion years.” They provide “a unique opportunity to learn about how our sun, Earth, planets, and even life began.”
The last seven months have been the most critical time in the €1.3 billion project. Before January, Rosetta had spent almost three years in hibernation: it was almost entirely shut down while it was too far from the Sun to draw enough energy for charging its batteries and keeping its instruments running. It drifted instead with the gravitational pull of the Sun and planets.
On that day in January, it was time to begin maneuvering toward the comet. Inside the European Space Agency’s operations center in Darmstadt, Germany, tension grew at the appointed time for Rosetta’s awakening. The scientists would know it had happened when a flat signal on a green monitor finally showed a peak. But 20 minutes after the scheduled time, there was nothing. Feuerbacher told me that there was a deep silence in the room. The European astronaut Thomas Reiter sent Feuerbacher a text message: “Are we a bit late Berndt?”
“Wait, Thomas, wait,” Feuerbacher says he replied. “It’s so far away and has many things to do before telling us she is awake. Open panels, heat up a bit, point its antenna toward Earth, trying to convey, and maybe it fails at the first attempt.”
When the signal on the screen finally spiked a few minutes later, applause burst through the hall. Operations staff put their fists skyward and hugged each other.
After Rosetta’s lander, known as Philae, plunges to the surface of the comet in November, its biggest challenge will be staying there. A comet has such little gravity that Philae could easily bounce from its surface and back into space. But Philae has an anchor to bite into the comet’s surface—a moment that will have everyone in the Darmstadt center holding their breath again.
__________________________________________________ ______
Last edited by Zeno; 08-07-2014 at 11:12 AM.
08-08-2014
, 01:10 AM
08-08-2014
, 03:00 AM
08-08-2014
, 03:38 AM
It (comet) has escape velocity of 0.5m/sec. That is small but not entirely insignificant. If they can get to speeds close to that it wont be necessarily a permanent loss if it doesnt get attached but that will depend also on what methods they have to retry if it fails the first time. They say it will approach at 1m/s trying to use harpoons to attach itself to the comet;
"The lander, named Philae, will approach Churyumov–Gerasimenko at relative speed around 1 m/s (2.2 mph; 3.6 km/h) and on contact with the surface, two harpoons will be fired into the comet to prevent the lander from bouncing off. Additional drills are used to further secure the lander on the comet. After its attachment to the comet, expected to take place in November 2014, the lander will begin its science mission."
I wonder how hard it would be to approach with very small speed gradually, self correcting, until it actually touches. It might be very hard to reach such small speeds for such kind of vehicle and then stabilize also at touch. But in principle if the object could get to sub 0.5m/sec by losing somehow energy with each collision it would eventually rest at some point of the comet after many bounces even if all went to hell initially. Of course you want to settle on a proper location with a certain orientation too and not damage any equipment with bounces lol.Then you have the rotation of the object itself say 12 h for some 2km crude radius thing (so rotation itself is 0.3m/sec). Maybe an alternative design could use both approaches to be safer that it gets there nomatter what and eventually open. I am sure they have tested how harpoons lock to a variety of densities, just hope it doesnt hit something very hard that completely rejects it or breaks "ground" in pieces leaving nothing solid to hang on to.
The comet itself has ridiculously small density almost 7-8 times less than water on avg but that is an average so i wonder how it fluctuates around that value locally. I imagine it as some kind of ice ground dirt mix with lots of empty spaces in between chunks.
Trying to lock with harpoons to something in the near absence of gravity is tough to imagine. It ought to be different. I wonder if you can even test it in free fall inside an airplane against various materials and see what happens. What prevents the material you strike for example from breaking into pieces all of it effectively scattering in different directions unable to be held together by its own weight (because its tiny) (gravity=0.0001g). Kind of like hitting sand in free fall that is held together with mostly electrostatic forces, having rested there after losing all relative motions in such small g environment. Experiments done at shuttle years ago with how materials are held together in such environment may help anticipate that.
"2014
20 January – At 10:00 UTC the spacecraft computer was taken out of hibernation mode and started post-hibernation procedures. Rosetta restored communications with ESOC through NASA's Goldstone ground station at 18:18 UTC.[65][66]
May to July - Starting on 7 May, Rosetta began orbital correction manoeuvres to bring itself into orbit around 67P/C-G. At the time of the first deceleration burn Rosetta was approximately 2,000,000 km (1,200,000 mi) away from 67P/C-G and had a relative velocity of +775 m/s (2,540 ft/s); by the end of the last burn, which occurred on 23 July, the distance had been reduced to just over 4,000 km (2,500 mi) with a relative velocity of +7.9 m/s (26 ft/s).[10][67] In total eight burns were used to align the trajectories of Rosetta 67P/C-G with the majority of the deceleration occurring during three burns: Delta-v's of 291 m/s (950 ft/s) on 21 May, 271 m/s (890 ft/s) on 4 June, and 91 m/s (300 ft/s) on 18 June.[10]
14 July - The OSIRIS on-board imaging system returned images of Comet 67P/C-G which confirm the irregular structure of the comet, and suggest that it may be a contact binary, though other formation scenarios exist.[68][69]
6 August - Rosetta arrives at 67P/C-G, approaching to 100 km (62 mi) and carrying out a thruster burn that reduces its relative velocity to 1 m/s (3.3 ft/s).[70][71][72]
Future milestones
August 2014 - Comet mapping and characterisation, to determine a stable orbit and viable landing location for Philae.
November 2014 - Philae lands on the surface of 67P/G-C.
November 2014 to December 2015 - Rosetta escorts the comet around the Sun.
December 2015 - End of mission."
"The lander, named Philae, will approach Churyumov–Gerasimenko at relative speed around 1 m/s (2.2 mph; 3.6 km/h) and on contact with the surface, two harpoons will be fired into the comet to prevent the lander from bouncing off. Additional drills are used to further secure the lander on the comet. After its attachment to the comet, expected to take place in November 2014, the lander will begin its science mission."
I wonder how hard it would be to approach with very small speed gradually, self correcting, until it actually touches. It might be very hard to reach such small speeds for such kind of vehicle and then stabilize also at touch. But in principle if the object could get to sub 0.5m/sec by losing somehow energy with each collision it would eventually rest at some point of the comet after many bounces even if all went to hell initially. Of course you want to settle on a proper location with a certain orientation too and not damage any equipment with bounces lol.Then you have the rotation of the object itself say 12 h for some 2km crude radius thing (so rotation itself is 0.3m/sec). Maybe an alternative design could use both approaches to be safer that it gets there nomatter what and eventually open. I am sure they have tested how harpoons lock to a variety of densities, just hope it doesnt hit something very hard that completely rejects it or breaks "ground" in pieces leaving nothing solid to hang on to.
The comet itself has ridiculously small density almost 7-8 times less than water on avg but that is an average so i wonder how it fluctuates around that value locally. I imagine it as some kind of ice ground dirt mix with lots of empty spaces in between chunks.
Trying to lock with harpoons to something in the near absence of gravity is tough to imagine. It ought to be different. I wonder if you can even test it in free fall inside an airplane against various materials and see what happens. What prevents the material you strike for example from breaking into pieces all of it effectively scattering in different directions unable to be held together by its own weight (because its tiny) (gravity=0.0001g). Kind of like hitting sand in free fall that is held together with mostly electrostatic forces, having rested there after losing all relative motions in such small g environment. Experiments done at shuttle years ago with how materials are held together in such environment may help anticipate that.
"2014
20 January – At 10:00 UTC the spacecraft computer was taken out of hibernation mode and started post-hibernation procedures. Rosetta restored communications with ESOC through NASA's Goldstone ground station at 18:18 UTC.[65][66]
May to July - Starting on 7 May, Rosetta began orbital correction manoeuvres to bring itself into orbit around 67P/C-G. At the time of the first deceleration burn Rosetta was approximately 2,000,000 km (1,200,000 mi) away from 67P/C-G and had a relative velocity of +775 m/s (2,540 ft/s); by the end of the last burn, which occurred on 23 July, the distance had been reduced to just over 4,000 km (2,500 mi) with a relative velocity of +7.9 m/s (26 ft/s).[10][67] In total eight burns were used to align the trajectories of Rosetta 67P/C-G with the majority of the deceleration occurring during three burns: Delta-v's of 291 m/s (950 ft/s) on 21 May, 271 m/s (890 ft/s) on 4 June, and 91 m/s (300 ft/s) on 18 June.[10]
14 July - The OSIRIS on-board imaging system returned images of Comet 67P/C-G which confirm the irregular structure of the comet, and suggest that it may be a contact binary, though other formation scenarios exist.[68][69]
6 August - Rosetta arrives at 67P/C-G, approaching to 100 km (62 mi) and carrying out a thruster burn that reduces its relative velocity to 1 m/s (3.3 ft/s).[70][71][72]
Future milestones
August 2014 - Comet mapping and characterisation, to determine a stable orbit and viable landing location for Philae.
November 2014 - Philae lands on the surface of 67P/G-C.
November 2014 to December 2015 - Rosetta escorts the comet around the Sun.
December 2015 - End of mission."
Last edited by masque de Z; 08-08-2014 at 04:03 AM.
11-09-2014
, 08:41 PM
11-11-2014
, 03:02 PM
11-12-2014
, 08:00 AM
11-12-2014
, 08:25 AM
Quote:
First great photos and info
http://www.technologyreview.com/view...comet-landing/
From above link:
Alessandro Ovi
August 6, 2014
European Space Agency Reaches Verge of Breakthrough Comet Landing
Images sent back from space probe bring a historic comet mission into clear focus.
This is no ordinary rock. It’s the surface of a comet somewhere between Jupiter and Mars, and it took a European space probe known as Rosetta 10 years to get there before it sent back these unprecedented images today.
Rosetta took these pictures after a series of maneuvers in which it fired thrusters to position itself less than 100 kilometers above the surface of the comet, known as 67P/Churyumov-Gerasimenko. The crucial next step is expected to come in November, when Rosetta will send down a lander to the surface. Scientists hope the lander’s explorations will yield clues not only about this particular comet, but also about the role such chunks of rock and ice have played in celestial history. In the words of my friend Berndt Feuerbacher, a German scientist who is a former president of the International Astronautical Federation: “Comets are relics from the origin of our solar system, kept in a kind of cosmic deep freeze far beyond the outer planets, unchanged in 4.5 billion years.” They provide “a unique opportunity to learn about how our sun, Earth, planets, and even life began.”
The last seven months have been the most critical time in the €1.3 billion project. Before January, Rosetta had spent almost three years in hibernation: it was almost entirely shut down while it was too far from the Sun to draw enough energy for charging its batteries and keeping its instruments running. It drifted instead with the gravitational pull of the Sun and planets.
On that day in January, it was time to begin maneuvering toward the comet. Inside the European Space Agency’s operations center in Darmstadt, Germany, tension grew at the appointed time for Rosetta’s awakening. The scientists would know it had happened when a flat signal on a green monitor finally showed a peak. But 20 minutes after the scheduled time, there was nothing. Feuerbacher told me that there was a deep silence in the room. The European astronaut Thomas Reiter sent Feuerbacher a text message: “Are we a bit late Berndt?”
“Wait, Thomas, wait,” Feuerbacher says he replied. “It’s so far away and has many things to do before telling us she is awake. Open panels, heat up a bit, point its antenna toward Earth, trying to convey, and maybe it fails at the first attempt.”
When the signal on the screen finally spiked a few minutes later, applause burst through the hall. Operations staff put their fists skyward and hugged each other.
After Rosetta’s lander, known as Philae, plunges to the surface of the comet in November, its biggest challenge will be staying there. A comet has such little gravity that Philae could easily bounce from its surface and back into space. But Philae has an anchor to bite into the comet’s surface—a moment that will have everyone in the Darmstadt center holding their breath again.
__________________________________________________ ______
http://www.technologyreview.com/view...comet-landing/
From above link:
Alessandro Ovi
August 6, 2014
European Space Agency Reaches Verge of Breakthrough Comet Landing
Images sent back from space probe bring a historic comet mission into clear focus.
This is no ordinary rock. It’s the surface of a comet somewhere between Jupiter and Mars, and it took a European space probe known as Rosetta 10 years to get there before it sent back these unprecedented images today.
Rosetta took these pictures after a series of maneuvers in which it fired thrusters to position itself less than 100 kilometers above the surface of the comet, known as 67P/Churyumov-Gerasimenko. The crucial next step is expected to come in November, when Rosetta will send down a lander to the surface. Scientists hope the lander’s explorations will yield clues not only about this particular comet, but also about the role such chunks of rock and ice have played in celestial history. In the words of my friend Berndt Feuerbacher, a German scientist who is a former president of the International Astronautical Federation: “Comets are relics from the origin of our solar system, kept in a kind of cosmic deep freeze far beyond the outer planets, unchanged in 4.5 billion years.” They provide “a unique opportunity to learn about how our sun, Earth, planets, and even life began.”
The last seven months have been the most critical time in the €1.3 billion project. Before January, Rosetta had spent almost three years in hibernation: it was almost entirely shut down while it was too far from the Sun to draw enough energy for charging its batteries and keeping its instruments running. It drifted instead with the gravitational pull of the Sun and planets.
On that day in January, it was time to begin maneuvering toward the comet. Inside the European Space Agency’s operations center in Darmstadt, Germany, tension grew at the appointed time for Rosetta’s awakening. The scientists would know it had happened when a flat signal on a green monitor finally showed a peak. But 20 minutes after the scheduled time, there was nothing. Feuerbacher told me that there was a deep silence in the room. The European astronaut Thomas Reiter sent Feuerbacher a text message: “Are we a bit late Berndt?”
“Wait, Thomas, wait,” Feuerbacher says he replied. “It’s so far away and has many things to do before telling us she is awake. Open panels, heat up a bit, point its antenna toward Earth, trying to convey, and maybe it fails at the first attempt.”
When the signal on the screen finally spiked a few minutes later, applause burst through the hall. Operations staff put their fists skyward and hugged each other.
After Rosetta’s lander, known as Philae, plunges to the surface of the comet in November, its biggest challenge will be staying there. A comet has such little gravity that Philae could easily bounce from its surface and back into space. But Philae has an anchor to bite into the comet’s surface—a moment that will have everyone in the Darmstadt center holding their breath again.
__________________________________________________ ______
Is this a fact or just a hoax just like the news I've heard from NASA about the 8 days of darkness this coming December?
11-12-2014
, 12:24 PM
11-12-2014
, 02:29 PM
Darn it, I missed it. But looks like the landing was a success — cool.
What are we expecting from it? I mean, I can imagine the science, but what in terms of public-friendly stuff — pictures? Video?
Magnitude listed as 19.29. Pity — it would be cool to be able to look up and say yep, there it is.
Edit: Apparently its estimated maximum magnitude is 12.
(I have a telescope, a 90mm refractor that's theoretically pretty damned good if I could get a mount for it, but I mean naked eye.)
What are we expecting from it? I mean, I can imagine the science, but what in terms of public-friendly stuff — pictures? Video?
Magnitude listed as 19.29. Pity — it would be cool to be able to look up and say yep, there it is.
Edit: Apparently its estimated maximum magnitude is 12.
(I have a telescope, a 90mm refractor that's theoretically pretty damned good if I could get a mount for it, but I mean naked eye.)
11-12-2014
, 02:55 PM
Maybe the attachment is not secure yet, landed on soft ground or something like i had been afraid using the reference on density months ago but it seems these objects are probably the result of breaking of bigger ones billions of years ago (plus whatever each visit near the sun does to them) so they should have parts that are strong enough moreover the small density (updated as 40% of water) and tiny gravity that could suggest parts that are very soft often or at least areas of vacuum. Maybe they will try again another strike to secure it for real after they have been informed exactly how it looks now? They need to know how it is because any thrust can produce recoil effect if unlucky.
size for comparison;
size for comparison;
Last edited by masque de Z; 11-12-2014 at 03:00 PM.
11-12-2014
, 08:40 PM
11-13-2014
, 04:14 AM
