Image from the Philae lander as it approached the surface. The dust-covered boulder at upper right is about 5 meters (16.4 feet) across. The dust might have originated through vaporization of ice on the boulder itself or deposited there by dust settling from jets elsewhere. Credit: ESA
First photo released of Comet 67P/C-G taken by Philae during its descent. The view is just 1.8 miles above the comet. Credit: ESA
Hey, we’re getting closer! This photo was taken by Philae’s ROLIS instrument just 1.8 miles (3 km) above the surface of 67P/Churyumov-Gerasimenko at 8:38 a.m. (CST) today. The ROLIS instrument is a down-looking imager that acquires images during the descent and doubles as a multi-wavelength close-up camera after the landing. The aim of the ROLIS experiment is to study the texture and microstructure of the comet’s surface. ROLIS (ROsetta Lander Imaging System) is a descent and close-up camera on the Philae lander.
I know, I know. You got a fever for more comet images the way Christopher Walken on Saturday Night Live couldn’t get enough cowbell.
Just for a little flavor of the rugged landscape Philae was headed toward earlier today, this photo was taken recently by Rosetta 4.8 miles (7.7 km) from the comet’s surface. Credit: ESA
Key scientists in a media briefing this afternoon highlighted the good news and the bad news about the landing. We reported earlier that both the harpoons and top thrusters failed to fire and anchor the lander to the comet. Yet land it did – maybe more than once! A close study of the data returned seems to indicate that Philae, without its anchors, may have touched the surface and then lifted off again, turning itself from the residual angular momentum left over after its flywheel was shut down. Stephan Ulamec, Philae Landing Manager, got a appreciative laugh from the crowd when he explained it this way: Maybe today we didn’t just land once. We landed twice!”
Stephan Ulamec, Philae Lander Manager. Credit: ESA
Telemetry from the probe has been sporadic. Data streams come in strong and then suddenly cut out only to return later. These fluctuations in the radio link obviously have the scientists concerned and as yet, there’s no explanation for them. Otherwise, Philae landed in splendid fashion almost directly at the center of its planned “error ellipse”.
Instruments on Philae are functioning normally and gathering data as you read this. Ulamec summed up the situation nicely: “It’s complicated to land and also complicated to understand the landing.”
Scientists and mission control will work to hopefully resolve the harpoon and radio link issues. The next live webcast begins tomorrow starting at 7 a.m. (CST). Although nothing definite was said, we may see more images arriving still today, so stop by later.
Just released "farewell photo" taken by the Philae lander as it departed Rosetta around 2:30 a.m. (CST) today. It shows the one of the solar arrays. Credit: ESA/Rosetta/Philae/CIVA
Anticipation is intense as the Philae lander free-falls to the surface of Comet Churyumov-Gerasimenko this morning. The final “Go” for separation from the Rosetta spacecraft was given around 2:30 a.m.; Philae’s now well on its way to Agilkia, the target landing site atop the 67P/C-G’s largerEverything is running smoothly except for one potential problem. During checks on the lander’s health, it was discovered that the active descent system, which provides a thrust to avoid rebound at the moment of touchdown, can’t be activated.
Artist impression of Philae separating from Rosetta earlier this morning. The lander is now free-falling to the comet under the influence of its gravity. Credit: ESA
At touchdown, as Philae anchors itself to the comet with harpoons and ice screws on each of its legs, the thruster on top of the lander is supposed to push it down to counteract the force of the harpoon firing in the opposite direction.
Klim Churyumov (left) Svetlana Gerasimenko are both at ESA today during the historic landing on the comet they discovered on September 20, 1969. Credit: ESA TV
“The cold gas thruster on top of the lander does not appear to be working so we will have to rely fully on the harpoons at touchdown,”says Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center.
The Philae that could! The lander photographed during its descent by Rosetta. Credit: ESA/Rosetta/MPS for Rosetta Team/
Philae is on target to land on the comet around 9:37 a.m. CST (15:37 UT). Confirmation of touchdown will take about 28 minutes as the signal, traveling at the speed of light, works its way back on Earth. As Philae floats down to the comet it not only has to deal with the 67P/C-G’s gravity but also the cloud of dust and ice grains escaping from the surface. Check back for regular updates and photos!
Tense control room during the Philae landing confirmation Time: 9:48 a.m. CST. Credit: ESA
Magnetic field lines bound up in the sun’s wind pile up and drape around a comet’s nucleus to shape the blue ion tail. Notice the oppositely-directed fields on the comet’s backside. The top set points away from the comet; the bottom set toward. In strong wind gusts, the two can be squeezed together and reconnect, releasing energy that snaps off a comet’s tail. Credit: Tufts University
Tune in to the song of Comet Churyumov-Gerasimenko
Scientists can’t figure exactly why yet, but Comet 67P/Churyumov-Gerasimenko has been singing since at least August. Listen to the video – what do you think? I hear a patter that sounds like frogs, purring and ping-pong balls. The song is being sung at a frequency of 40-50 millihertz, much lower than the 20 hertz – 20 kilohertz range of human hearing. Rosetta’s magnetometer experiment first clearly picked up the sounds in August, when the spacecraft drew to within 62 miles (100 km) of the comet. To make them audible Rosetta scientists increased their pitch 10,000 times.
The sounds are thought to be oscillations in the magnetic field around the comet. They were picked up by the Rosetta Plasma Consortium, a suite of five instruments on the spacecraft devoted to observing interactions between the solar plasma and the comet’s tenuous coma as well as the physical properties of the nucleus. A far cry from the stuff you donate at the local plasma center, plasma in physics is an ionized gas. Ionized means the atoms in the gas have lost or gained an electron through heating or collisions to become positively or negatively charged ions. Common forms of plasma include the electric glow of neon signs, lightning and of course the Sun itself.
Having lost their neutrality, electric and magnetic fields can now affect the motion of particles in the plasma. Likewise, moving electrified particles affect the very magnetic field controlling them.
Scientists think that neutral gas particles from vaporizing ice shot into the coma become ionized under the action of ultraviolet light from the Sun. While the exact mechanism that creates the curious oscillations is still unknown, it might have something to do with the electrified atoms or ions interacting with the magnetic fields bundled with the Sun’s everyday outpouring of plasma called the solar wind. It’s long been known that a comet’s electrified or ionized gases present an obstacle to the solar wind, causing it to drape around the nucleus and shape the streamlined blue-tinted ion or gas tail.
“This is exciting because it is completely new to us. We did not expect this, and we are still working to understand the physics of what is happening,” said Karl-Heinz Glassmeier, head of Space Physics and Space Sensorics at the Technical University of Braunschweig, Germany.
While 67P C-G’s song probably won’t make the Top 40, we might listen to it just as we would any other piece of music to learn what message is being communicated.
After a ten year journey that began with the launch from the jungles of French Guyana, landing Philae is not the end of mission, it is the beginning of a new phase. A successful landing is not guaranteed but the ESA Rosetta team is now ready to release Philae on its one way journey. (Photo Credits: ESA/NASA, Illustration: J.Schmidt)
We are now in the final hours before Rosetta’s Philae lander is released to attempt a first-ever landing on a comet. At 9:03 GMT (1:03 AM PST) on Wednesday, November 12, 2014, Philae will be released and directed towards the surface of comet 67P/Churyumov–Gerasimenko. 7 hours later, the lander will touch down.
Below you’ll find a timeline of events, info on how to watch the landing, and an overview of how the landing will (hopefully) work.
In human affairs, we build contingencies for missteps, failures. With spacecraft, engineers try to eliminate all single point failures and likewise have contingency plans. The landing of a spacecraft, be it on Mars, Earth, or the Moon, always involves unavoidable single point failures and points of no return, and with comet 67P/Churyumov–Gerasimenko, Rosetta’s Philae lander is no exception.
Rosetta’s and Philae’s software and hardware must work near flawlessly to give Philae the best chance possible of landing safely. And even with flawless execution, it all depends on Philae’s intercepting a good landing spot on the surface. Philae’s trajectory is ballistic on this one way trip to a comet’s surface. It’s like a 1 mile per hour bullet. Once fired, it’s on its own, and for Philae, its trajectory could lead to a pristine flat step or it could be crevasse, ledge, or sharp rock.
The accuracy of the landing is critical but it has left a 1 square kilometer of uncertainty. For this reason, engineers and scientists had to survey the whole surface for the most mild features. Comet 67P has few areas that are not extreme in one way or another. Site J, now called Agilkia, is one such site.
When first announced in late September, the time of release was 08:35 GMT (12:35 AM PST). Now the time is 9:03 GMT. The engineers and computer scientists have had six weeks to further refine their trajectory. It’s a complicated calculation that has required running the computer simulation of the descent backwards. Backwards because they can set a landing time then run Philae backwards to the moment of release. The solution is not just one but many, thousands or millions if you want to look in such detail. With each release point, the engineers had to determine how, or if, Rosetta could be navigated to that coordinate point in space and time.
Arrival time of the radio signal with landing status: 16:30 GMT
Rosetta/Philae at 500 million km [320 million miles], 28.5 minutes light time
Arrival of First Images: 06:00 GMT, November 13, 2014
The gravity field of the comet is so weak, it is primarily the initial velocity from Rosetta that delivers Philae to the surface. But the gravity is there and because of the chaotic shape and unknown (as yet) mass distribution inside, the gravity will make Philae move like a major league knuckleball wobbling to the plate and a batter. Furthermore, the comet during the seven hour trip will make half a rotation. The landing site will not be in site when Philae is released.
And as Philae is on final approach, it will use a small rocket not to slow down but rather thrust it at the comet, landing harpoons will be fired, foot screws will try to burrow into the comet, and everyone on Earth will wait several minutes for a message to be relayed from Philae to Rosetta to the Deep Space Network (DSN) antennas on Earth. Philae will be on its own as soon as it leaves Rosetta and its fate is a few hours away.
Why travel to a comet? Comets represent primordial material leftover from the formation of the solar system. Because cometary bodies were formed and remained at a distance from the heat of the sun, the materials have remained nearly unchanged since formation, ~4.5 billion years ago. By looking at Rosetta’s comet, 67P/Churyumov–Gerasimenko, scientists will gain the best yet measurements of a comet’s chemical makeup, its internal structure created during formation, and the dynamics of the comet as it approaches the warmth of the Sun. Theories propose that comets impacting on Earth delivered most of the water of our oceans. If correct, then we are not just made of star-stuff, as Carl Sagan proclaimed, we are made of comet stuff, too. Comets may also have delivered the raw organic materials needed to start the formation of life on Earth.
Besides the ESA live feeds, one can take a peek at NASA’s Deep Space Network (DSN) at work to see which telescopes are communicating with Rosetta. JPL’s webcast can watched below:
Two objects with comet-like orbits flew through the solar system in 2013 and 2014, but with little to no activity on their surfaces. At left is C/2013 P2 Pan-STARRS and at right, C/2014 S3 Pan-STARRS. Credit: University of Hawaii Institute for Astronomy
What’s a comet that doesn’t look like a comet? The question sounds contradictory, but astronomers believe these objects exist. As comets pass through the solar system, they bleed ice and dust as the Sun’s effects wash over their small bodies. Over time, some of the objects can keep going like ghost ships — just without the ices that used to produce a show.
There already is a class of objects called damocloids that are believed to be extinct comets, but scientists believe they have found something new with two mysterious visitors — what they call “naked” comets — from the outer Solar System.
The two objects originate from an area that astronomers term the Oort Cloud, a hypothetical collection of icy bodies that orbit as far away as 100,000 times the Earth-Sun distance (astronomical unit). Gravitational influences then kick the objects in towards the Sun and they commence orbits that can last millions of years.
When Jan Oort first proposed this concept in the 1950s, he said that some of the objects there could have only a tiny layer of ice that would immediately evaporate during the first pass in near the Sun. That’s what astronomers think they are seeing in objects C/2013 P2 Pan-STARRS and C/2014 S3 Pan-STARRS.
The familiar solar system with its 8 planets occupies a tiny space inside a large spherical shell containing trillions of comets – the Oort Cloud. Credit: Wikimedia Commons
“Objects on long-period orbits like this usually exhibit cometary tails, for example Comet ISON and Comet Hale Bopp, so we immediately knew this object was unusual,” stated Karen Meech, an astronomer at the University of Hawaii at Manoa who led the research. “I wondered if this could be the first evidence of movement of solar system building blocks from the inner solar system to the Oort Cloud.”
The automated Pan STARRS1 survey telescope found C/2013 P2 in August 2013, with astronomers remarking its orbit resembled that of a comet. But, C/2013 P2’s surface was quiet. A second look the next month with the 8-meter Gemini North telescope in Hawaii revealed a little bit of light and a dusty tail. The object stayed at about the same brightness, even when it got to its closest approach to the Sun (2.8 AU) in February 2014.
After the comet swung around the Sun and telescopes could look at it again, examinations with the Gemini North telescope found something weird: the object’s spectrum looked red. This makes it look more like a Kuiper Belt object — something that roams in shallower waters in the Solar System, beyond Neptune’s orbit — than a typical comet or asteroid.
While results were still being analyzed, in September a NASA survey found an object with curiously similar properties: C/2014 S3. When it was found, the object had already passed its closest approach to the Sun in August. But from analyzing the orbit, the scientists saw it had come to only within 2 AU. Also, the first observations showed barely a tail at all.
Distribution of Kuiper belt objects (green), along with various other outer Solar System bodies, based on data from the Minor Planet Center. [Credit: Minor Planet Center; Murray and Dermott]A closer examination with the Canada-France-Hawaii Telescope revealed a mystery: the spectrum was more blue than red, hinting at materials similar to what you would find in the inner Solar System. The team says this could be a new class of objects altogether.
“I’ll be thrilled if this object turns out to have a surface composition similar to asteroids in the inner part of the asteroid belt. If this is the case, it will be remarkable for a body found so far out in the Solar System,” stated Meech.
“There are several models that try to explain how the planets grew in the early Solar System, and some of these predict that material formed close to the sun could have been thrown outward into the outer Solar System and Oort Cloud, where it remains today. Maybe we are finally seeing that evidence.”
Results were presented today (Nov. 10) at the Division of Planetary Sciences meeting of the American Astronomical Society in Tucson, Arizona. A press release did not say if the research is peer-reviewed, or state publication plans.
On a hiking holiday in the Swiss Alps this summer, it struck me that an Alpine setting — or its equivalent in other countries – looking at kilometer-sized objects at distances up to a dozen or dozens of kilometers is probably the situation where we can best develop an intuition about just how large the nucleus of 67P/Churyumov–Gerasimenko is.
Today, I took the time to insert the nucleus in one of my holiday snaps, using one of the Rosetta Navcam images that ESA has just released under a Creative Commons license. My original image was taken from a hiking trail between the Swiss villages of Bettmeralp and Fiescheralp, looking South-East towards Italy. The first image, above, has the comet floating just behind the first mountain range in the Binntal valley.
This is a fairly big sucker, even compared with the mountains in front and behind. In this image, the cometary nucleus is at a distance of about 7.2 kilometers (4.3 miles) from the observer.
I’ve also set the nucleus a bit farther back: Just beyond the most distant mountain range dominating the center of the image, which includes Italy’s Mount Cervandone, 3210 meters (10,530 ft.) high. It’s sitting right beyond the most distant mountain range visible in the original image (at a distance of about 14 km [8.7 mi] from the observer), and still looks fairly impressive:
Image credit: M. Pössel/HdA using an image from ESA/Rosetta/NAVCAM. Released under CC BY-SA IGO 3.0
And this, I guess, makes a cometary nucleus a nice link between the terrestrial and the cosmic: It is comparable to the largest structures we can directly see here on Earth, and does not have the enormous (astronomical!) dimensions so often encountered in space, whose size we cannot directly imagine.
On November 12, we’ll hopefully have another comparison: How will the view transmitted by the Philae lander correspond to terrestrial landscapes? What impression of size will we get then? Good luck, Rosetta and Philae!
Production notes
The images were made from two images shot with a Canon 70D with the standard kit lens – one showing the landscape, and a separate one showing more suitable sky and clouds on a different day, in a different location. Using Gimp, I inserted a fairly well-known Navcam image from ESA’s Flickr collection. The image came with the information that its resolution was 5.3 m per pixel; I used this plus distance information from Google Maps and elevation information via Mapcoordinates, combined with a test image giving me my camera’s pixel scale, to estimate the appropriate size of the cometary nucleus in the image (no lens distortion; camera modeled as a simple pinhole camera).
We can only imagine what the meteor storm from Comet Siding Spring must have looked like standing on the surface of Mars on October 19, 2014. NASA scientists announced today that the planet experienced an exceptional shower during the comet's flyby, saturating the sky. Source: Stellarium
“Thousands of meteors per hour would have been visible — truly astounding to the human eye.” That’s Nick Schneider’s description of what you and I would have seen standing on Mars during Comet Siding Spring’s close flyby last month. “It would have been really mind-blowing,” he added. Schneider is instrument lead for MAVEN’s Imaging Ultraviolet Spectrograph (IUVS).
He and a group of scientists who work as lead investigators for instruments on the MAVEN and Mars Reconnaissance Orbiter (MRO) spacecraft shared the latest results from the comet flyby during a media teleconference earlier today. There were many surprises. Would we expect anything less from a comet?
Here’s a summary of the results:
A very dusty ice ball – The comet’s dust tail and the amount of dust in its coma were much larger than expected, prompting Jim Green, director of NASA’s Planetary Science Division in Washington, to remark: “It makes me very happy we hid them (the spacecraft) on the backside of Mars. That really saved them.” Siding Spring dumped several tons of fine dust into the Martian atmosphere prompting a spectacular meteor shower and possibly causing a yellow, twilight afterglow above the Curiosity landing site from vaporizing sodium atoms contained in the minerals. That, and dust in the mid-levels of the atmosphere at the time contributed to the rover’s difficulty in getting good photos of the comet itself. Scientists are still examining the images.
MAVEN’s Ultraviolet Imaging Spectrograph (IUVS) uses limb scans to map the chemical makeup and vertical structure across Mars’ upper atmosphere. It detected strong enhancements of magnesium and iron from ablating incandescing dust from Comet Siding Spring. Credit: NASAI’m not big into graphs either, but check out the heavy metal drama going on here. On the left is the “before” scan from MAVEN’s IUVS instrument; on the right, during the comet’s close approach. The spike in magnesium from vaporizing comet dust is impressive. Ionized magnesium is the strongest spike with neutral and ionized iron on the left in smaller amounts. Both elements are common in meteorites as well as on Earth. Credit: NASAProfiles showing spikes in the amounts of eight different metals over time detected in Mars’ atmosphere by MAVEN’s Neutral Gas and Ion Mass Spectrometer (NGIMS). The emissions faded within a short time, but chemicals from the comet will continue to interact with the Martian atmosphere over time. Credit: NASA
Chemistry of Mars’ atmosphere changed – Dust vaporized in the intense meteor shower produced a striking increase in the amount of magnesium, iron and others metals in Mars’ upper atmosphere. “We were pressed back in our chairs,” said Mike Schneider. The bombardment created a temporary new layer of comet-tainted air and may have acted as condensation nuclei for the formation of high-altitude clouds. MAVEN’s Neutral Gas and Ion Mass Spectrometer (NGIMS) recorded huge spikes in the levels of eight different metals during the comet’s passage and then trailed off a day or so later. “They came to MAVEN as a free sample from no less than an Oort Cloud comet,” said Mehdi Benna, instrument scientist for MAVEN’s Neutral Gas and Ion Mass Spectrometer.
The MARSIS instrument on the Mars Express is a ground penetrating radar sounder used to look for subsurface water and ice. It can also make soundings of the ionosphere. It was used to see the new ionospheric layer formed by vaporizing comet dust on October 19th. Credit: ESAThe Mars Express radar probed the ionosphere (upper atmosphere) at three different times. At top, before the comet arrived; middle, 7 hours later after the comet’s closest approach and bottom, hours later after the comet had departed. The middle graph shows a strong signal (blue horizontal bar) from the creation of a newly-ionized layer of the planet’s lower atmosphere from hot, fast-moving comet dust. Credit: ESA
Flaming comet dust creates new ionospheric layer – Comet dust slamming into the atmosphere at 125,000 mph (56 km/sec) knocked electrons loose from atoms in the thin Martian air 50-60 miles (80-100 km) high, ionizing them and creating a very dense ionization layer in the planet’s lower ionosphere seven hours after the comet’s closest approach. Normally, Mars ionosphere is only seen on the dayside of the planet, but even when the MARSIS instrumenton Mars Express beamed radio waves through the atmosphere on the nightside of the planet, it picked up a very strong signal.
54 red-filtered, false-color images of the comet’s nucleus-coma taken by the MRO’s HiRISE camera show changes in the flow of material leaving the comet. Based on the photos, the comet’s nucleus spins once every 8 hours. Credit: NASAThe five closest photos made with the HiRISE camera show the combined light of the nucleus and coma. Scale is 140-meter per pixel at top and 177-meters at bottom. Scientists will further process these images to separate the nucleus from the coma. Credit: NASA
Nucleus spins once during your work day – Comet Siding Spring’s icy core spins once every 8 hours and its irregular shape causes strong variations in the comet’s brightness. The comet’s size appears less certain – at least for the moment – with estimates anywhere between a few hundred meters to 2 km (1.2 miles). More analysis on images taken by MRO’s HiRISE camera should narrow that number soon.
CRISM photo and spectrum of Comet Siding Spring. The spectrum is “flat”, indicating we’re seeing ordinary sunlight reflecting off comet dust. The intriguing color variations in the image tell us the comet’s spewing dust particles of many sizes. Credit: NASA
Dust motes of many sizes – Color variations across Siding Spring’s coma seen by Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) indicate it’s releasing dust particles of different sizes – big and little.
The scientists involved in the encounter couldn’t be happier with how the instruments functioned and the amount of hard data returned. Said Jim Green: “We are so lucky to observe this once-in-a-lifetime event.” How true when you consider that it takes about 8 million years for a comet from the Oort Cloud, that vast reservoir of frozen comets extending nearly a light year from the Sun, to get here in the first place. Nick Schneider put it another way:
“Not only is this a free sample of the Oort Cloud in Mars’ atmosphere, but it gives us a chance to learn more about Mars itself.”
If you’d like to listen in to the hour-long teleconference at any time, it’ll be up for the next week or so HERE.
Rosetta, the scientific mission to explore a comet's surface. "Ambition", a short Sci-Fi film, set in the near future, and Rosetta, the children's fable, to encourage the next generations to undertake on the great adventures still to come. (Photo Credits: ESA, Platige Image, ESA Communications)
In the recently released Rosetta short film called “Ambition”, the master begins a story to his apprentice – “Once upon a time.” The apprentice immediately objects to his triteness. But he promises that it is worth the slight tribulation. Who could have imagined ten years ago that Rosetta would become so successful in two such contrasting approaches to telling a tale.
The Rosetta mission is part franchise and part scientific mission. In five days, Rosetta will reach a crossroad, a point of no return as epic as moments in Harry Potter or Lord of the Rings. A small mindless little probe called Philae will be released on a one-way trip to the surface of a comet. Win or lose, Philae will live on in the tale of a comet and a mission to uncover the mysteries of our planet’s formation.
ESA did not promise a good mission as Aidan Gillen promises a good story in Ambition. A space mission is never put in terms of a promise but rather it is thousands of requirements and constraints that formulate a mission plan and a spacecraft design. The European Space Agency put 1 billion Euros ($1.3 billion) to work and did so in what now looks like one of the greatest space missions of the first century of space exploration.
The Rosetta mission is actually two missions in one. There is the comet chaser, the orbiter – Rosetta and then the lander Philae. The design of Rosetta’s objectives is some part, probably in large part, was conceived by dismissing the presence of Philae. Make a space probe to a comet that just orbits the small body. Select your scientific instrumentations accordingly. Now add a small lander to the mission profile that will do something extraordinary – what Rosetta cannot do with its instrumentation. Finally, make sure that Rosetta has everything needed to support Philae’s landing on a comet.
Here is what they have as the game plan on November 12th (the sequence of events begins while its still November 11th in the Americas). These two times are absolutely non- trivial. They are finely tuned to a timepiece called 67P/Churyumov–Gerasimenko. If calculations were made in error, then Philae’s ultimate fate is unknown. Start exactly on time and Philae will be given the best chance at making a successful touchdown on the comet.
Separation of Philae from Rosetta: 09:03 GMT (10:03 CET)
Touchdown on the comet: 16:02 GMT (17:02 CET).
During this time, comet 67P/Churyumov–Gerasimenko will complete over half a rotation on its axis. To be exact, it will rotate 56.2977% of a full rotation. Comet 67P will have its back turned towards Rosetta as it holds the diminutive Philae for the last time and releases Philae for the first and only time.
Now that the ESA, with help from the graphic artists from Platige Image from Poland, has released something entertaining for the science fiction minded among us, they have again released a next episode in their children’s fable of Rosetta and Philae (video below). This cartoon of the final moments of Rosetta and Philae together preparing for the descent which could well be the final moments of Philae.
Philae could fail, crack like an egg on a sharp rock or topple over a cliff or into a crevasse on the surface of 67P. What happens to Philae will make for a Grimm’s fairy tale ending or something we would all prefer. In either case, the ESA is using graphic arts and storytelling to inspire the next generations to join in what our JFK called “great adventures of all time” [ref].
Through a contest something NASA and JPL have used several times to involve the public, the ESA asked the public to come up with a name for the landing site, site J. Out of the thousands of entries, 150 people suggested the name Agilkia [ref]. Alexandre Brouste from France, the designated winner, has been invited to watch the landing activities at Rosetta’s mission control in Darmstadt, Germany. It follows from the Eqyptian theme of the mission’s two probes. “Rosetta” comes from the clay tablet discovered in the 1800s that led to the deciphering of Egyptian hieroglyphics. Philae” is a island on the Nile which held magnificent Eqyptian temples. With the operation of the Aswan dam starting in 1902, the island of Philae was repeatedly flooded and the temple was at risk. UNESCO beginning in 1960 started a project to save the islands historic structures. They were all moved to a nearby Nile island called Agilkia [related U.T. article]. This becomes a part of the Rosetta story – a lander named Philae in reference to the obelisks used along with the Rosetta stone to decipher Eqyptian writings, departing its mother ship on a short but critical voyage to a final resting place, the landing site now called Agilkia.
Upon landing, a landing confirmation signal is expected from Philae via Rosetta at about 8:02 AM PST (11:02 AM EST, 17:02 Central European Time). Alexandre Brouste of France, the designated winner of the landing site naming contest will be in Darmstadt, Germany in mission control to watch the landing unfold with the Rosetta engineers and scientists. Surely, millions of citizens of the European Union and people worldwide will be watching via the World Wide Web.
The timeline and events to unfold as Philae, the lander is released from Rosetta, the comet orbiter. (Illustration Credit: ESA)
Previous Rosetta and Philae articles at Universe Today
In this panoramic view taken by NASA's Curiosity Rover on October 19th shortly after local sunset (6:11 p.m.), Comet Siding Spring is the single bright pixel at far upper left. Click for a high resolution version. Credit: NASA/JPL-Caltech/Malin Space Science Systems/James Sorenson
When Comet Siding Spring skimmed just 84,500 miles from Mars last month, NASA’s Opportunity and Curiosity Rovers – along with several orbiting Mars spacecraft – readied their cameras to record the historic flyby. Opportunity’s photos revealed a small, fuzzy blob against the stars of Cetus the Whale, but most of us searched in vain to find any trace of the comet among the blizzard of noise in pictures snapped by Curiosity. Yet it may be there after all.
In this before-and-after animation, you can see how much noise needed to be cleaned from the original photos to uncover the the comet. Credit: NASA/JPL-Caltech/Malin Space Science Systems/James Sorenson
In this panoramic image at top, assembled and processed by James Sorenson to remove the pervasive noise in the original photos, we see with a twilit landscape just after sundown. Look closely in the upper left hand corner and you’ll see a speck of light. That’s it! Combined with positional information, Sorenson tentatively identified that pixel as Comet C/2013 A1 Siding Spring. OK, it’s not much to look at but may be our best candidate for the hoped-for photo from Curiosity.
Comet Siding Spring near Mars in a composite image by the Hubble Space Telescope, capturing their positions between Oct. 18 8:06 a.m. EDT (12:06 p.m. UTC) and Oct. 19 11:17 p.m. EDT (Oct. 20, 3:17 a.m. UTC). Credit: NASA, ESA, PSI, JHU/APL, STScI/AURA
Remember that conditions were far from ideal when the picture was taken. There was considerable dust and haze in the Martian atmosphere over Gale Crater. Dust effectively absorbs and also scatters light. The bright twilight sky only made the comet more difficult to discern. If you’ve ever struggled to see Mercury at dusk on a hazy summer evening, you’ll understand what our robot was up against.
This single image is one of series that were acquired by the HRSC camera on board Mars Express during the comet Siding Spring flyby on October 19, 2014. Click to animate. Credit: ESA/DLR/FU Berlin
The European Space Agency’s Mars Express orbiter also chimed in with a recent set of comet images. As it flew by, Siding Spring was traveling at around 35 miles per second (56 km/sec) relative to Mars. Images were acquired at 17-second intervals at a resolution of 10.5 miles (17 km) per pixel. What do they show? The irregular shape might make you might think you’re seeing the actual shape of the comet’s nucleus. Unfortunately, that’s impossible because it’s less than a kilometer across and each pixel in the photo spans 17 km. Instead, we’re seeing the combined light of the nucleus and extended coma, the surrounding cloud of gas and dust. Why the images are pure black and white with no grey tones is unclear.
Two photos of comet C/2013 A1 Siding Spring taken 37 minutes apart by the CRISM imager when the comet was closest to Mars. The subtle colors seen are likely related to dust grain size or composition. The nucleus itself is not resolved. Credit: NASA/JPL/JHUAPL
Besides the theclose-up photo taken with the HiRISE camera on NASA’s Mars Reconnaissance Orbiter, its Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) got busy photographing the dusty inner coma generated when sunlight warms and vaporizes dust-laden ice in the nucleus. The scale of the left image is approximately 2.5 miles (4 km) per pixel; for the right image, it is about 3 miles (5 km) per pixel.
According to NASA, CRISM observed 107 different wavelengths of light in each pixel. Here, only three colors are shown. Researchers think the appearance of color variations in the inner coma could be due to the properties of the comet’s dust, possibly dust grain size or composition. More photos and results from all the spacecraft will appear in the weeks and months ahead as scientists continue their analyses.
Comet Siding Spring shows a condensed coma and hint of a tail in this photo taken on November 5, 2014. Credit: Alfons Diepvens
Comet Siding Spring has left Mars and its crew of robotic eyes behind as it crawls north into the constellation Serpens low in the southwest at dusk. Amateur astronomers are still keen to photograph it at every opportunity. Recent observations indicate a temporary re-brightening, though the comet remains a dim 11th magnitude object.
This "dark side" image of Comet 67P/Churyumov-Gerasimenko shows light backscattered from dust particles in the coma surrounding the comet, which helps scientists search for surface features. The picture was taken by the Rosetta spacecraft Sept. 29 from about 19 kilometers (12 miles). Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
How do you see a side of a comet that is usually shrouded in darkness? For the plucky scientists using the Rosetta spacecraft, the answer comes down to using dust to their advantage. They’re trying to catch a glimpse of the shadowed southern side using light scattering from dust particles in anticipation of watching the comet’s activity heat up next year.
Using Rosetta’s OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) instrument, scientists are diligently mapping Comet 67P/Churyumov-Gerasimenko’s surface features as it draws closer to the Sun. Funny enough, the shadowed side will be in full sunlight by the time the comet gets to its closest approach. This gives scientists more incentive to see what it looks like now.
The comet side is in shadow because its is not perpendicular to its orbital plane, the Max Planck Institute for Solar System Research stated. This means that areas of the comet can stay in shadow for months at a time. But using OSIRIS’ powerful receptors, scientists can get a few hints about what those surface features are, using dust scattering.
Playing with saturation levels in these images, scientists using the Rosetta’s spacecraft imaging system are able to get more information about surface features in the image at right. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
“For a normal camera, this tiny bit of scattered light would not help very much”, stated OSIRIS team member Maurizio Pajola from the University of Padua in Italy. A normal camera has eight bits per pixel of information (256 shades of gray), while OSIRIS’ 16 bits allow it to distinguish between 65,000 shades. “In this way, OSIRIS can see black surfaces darker than coal together with white spots as bright as snow in the same image,” he added.
The scientists were not specific in a press release about what they are seeing so far, but they said that in May 2015 they expect to get a lot more data very quickly — once the area goes into full sunlight.
Rosetta, a mission of the European Space Agency, has been orbiting the comet since August. Next Wednesday it will release a lander, Philae, that will attempt to make the first soft landing on a comet’s surface.
![Distribution of Kuiper belt objects (green), along with various other outer Solar System bodies, based on data from the Minor Planet Center. [Credit: Minor Planet Center; Murray and Dermott]](https://www.universetoday.com/wp-content/uploads/2014/01/Kuiper_belt.png)
