Tag: Rosetta

Scientists: Comet 67P/C-G’s make-up matches the rest of the solar system

9:33 am

A detailed review of the archived data from the Rosetta mission that studied Comet 67P/Churyumov-Gerasimenko closely in 2014-2016 now strongly suggests that the comet’s overall make-up closely matches the rest of the solar system.

“It turned out that, on average, [the comet’s] complex organics budget is identical to the soluble part of meteoritic organic matter”, explains [Nora Hänni of the University of Bern] and adds: “Moreover, apart from the relative amount of hydrogen atoms, the molecular budget of [comet 67P/C-G] also strongly resembles the organic material raining down on Saturn from its innermost ring, as detected by the INMS mass spectrometer onboard NASA’s Cassini spacecraft”.

“We do not only find similarities of the organic reservoirs in the Solar System, but many of [comet 67P/C-G]’s organic molecules are also present in molecular clouds, the birthplaces of new stars”, complements Prof. Dr. Susanne Wampfler, astrophysicist at the Center for Space and Habitability (CSH) at the University of Bern and co-author of the publication. “Our findings are consistent with and support the scenario of a shared presolar origin of the different reservoirs of Solar System organics, confirming that comets indeed carry material from the times long before our Solar System emerged.”

These results are not unexpected, but having those expectations confirmed was one of the main scientific goals of the Rosetta mission. Now, almost a decade later, the results are in.

One comment

Citizens enlisted to find changes to Comet 67P/C-G during Rosetta mission

9:56 am

The European Space Agency (ESA) and Zooniverse have partnered to create a new citizen science project, allowing anyone to more easily review the archive of high resolution photos taken by Rosetta of Comet 67P/C-G and look for changes that occurred during the probe’s mission to the comet.

“The Rosetta archive, which is openly accessible to scientists and the public, contains a vast amount of data collected by this extraordinary mission that have only been partially explored,” says Bruno Merín, head of ESA’s ESAC Science Data Centre near Madrid, Spain. “In the past few years, astrophotographers and space enthusiasts have spontaneously identified changes and signs of activity in Rosetta’s images. Except for a few cases, though, it has not been possible to link any of these events to surface changes, mostly due to the lack of human eyes sifting through the whole dataset. We definitely need more eyes!”

This is why ESA partnered with the Zooniverse, the world’s largest and most popular platform for people-powered research. The new Rosetta Zoo project presents a particular set of data: pairs of images collected by Rosetta’s OSIRIS camera showing Comet 67P’s surface before and after perihelion.

Volunteers are invited to view images of roughly the same region side by side and identify a variety of changes, from large-scale dust transport to comet chunks that moved or even vanished. Sometimes this may require zooming in or out a few times, or rotating the images to spot changes on different scales, getting up close and personal with the iconic comet.

Using Rosetta Zoo will require no software, nor will anyone need to register to use it. You simply go to the website and begin comparing pairs of images, for as long as you wish, marking differences you spot of the same locations.

Leave a comment

Scientists finally map Philae’s full route to its final landing site on Comet 67/C-G

12:53 pm

Philae's journey across Comet 67/C-G
Click for full resolution image.

Using archival data from Rosetta, scientists have finally been able to map out the full route and all impact points made by the lander Philae on its journey to land on the Comet 67P/C-G in November 2014.

All that was known previously was the location of the first contact, that there had been another impact following the rebound, and the location of the final landing site where Philae came to rest after two hours and where it was found towards the end of the Rosetta mission in 2016 . “Now we finally know the exact place where Philae touched down on the comet for the second time. This will allow us to fully reconstruct the lander’s trajectory and derive important scientific results from the telemetry data as well as measurements from some of the instruments operating during the landing process,” explains Jean-Baptiste Vincent from the DLR Institute of Planetary Research, who was involved in the research published today.

…Analysis of the data revealed that Philae had spent almost two full minutes – not unusual in this very low gravity environment – at the second surface contact point, making at least four different surface contacts as the lander ‘ploughed’ through the rugged landscape. A particularly remarkable imprint, which became visible in the images, was made when the top of Philae sank 25 centimetres into the ice at the side of an open crevice, leaving visible traces of the sample drill and the lander’s top. The peaks in the magnetic field data resulting from the boom movement show that Philae took three seconds to make this particular ‘dent’.

This new data about this particular impact has helped the scientists determine a great deal about the comet’s make-up and density, finding that it is extremely fluffy.

The parameters of surface contact showed that this ancient, 4.5-billion-year-old mixture of ice and dust is extraordinarily soft – it is fluffier than the froth on a cappuccino, the foam in a bathtub or the whitecaps of waves meeting the coast.

They also found that the interior has many voids comprising 75% of the interior, with the “boulders” between having the density of Styrofoam.

One comment

A UV aurora found on Comet 67P/C-G

9:06 am

Using data from Europe’s now completed Rosetta mission to Comet 67P/C-G, scientists have detected evidence that the comet’s interaction with the Sun’s solar wind creates an aurora above the comet in ultra-violet wavelengths.

The data indicate 67P/C-G’s emissions are actually auroral in nature. Electrons streaming out in the solar wind – the stream of charged particles flowing out from the Sun – interact with the gas in the comet’s coma, breaking apart water and other molecules. The resulting atoms give off a distinctive far-ultraviolet light. Invisible to the naked eye, far-ultraviolet has the shortest wavelengths of radiation in the ultraviolet spectrum.

Labeling this phenomenon as an aurora is a bit of hype, as nothing is visible. However, the discovery does tell scientists how this comet’s coma, produced when the comet heats up in its approach to the Sun, interacts with the solar wind, and this in turn can teach them more about that wind, as well as other comets.

One comment

New findings from Rosetta: Bouncing boulders and collapsing cliffs

10:13 am

cliff collapse on Comet 67P/C-G
Click for full image.

In reviewing the large image archive taken by Europe’s Rosetta probe while it orbited Comet 67P/C-G from 2014 to 2016, scientists have found more evidence of changes on its surface during its closest approach to the Sun, including a bouncing boulder and the collapse of large cliff.

The image on the right, reduced to post here, shows both wide (top) and close-up (bottom) views of the cliff collapse.

“This seems to be one of the largest cliff collapses we’ve seen on the comet during Rosetta’s lifetime, with an area of about 2000 square metres collapsing,” said Ramy, also speaking at EPSC-DPS today. … “Inspection of before and after images allow us to ascertain that the scarp was intact up until at least May 2015, for when we still have high enough resolution images in that region to see it,” says Graham, an undergraduate student working with Ramy to investigate Rosetta’s vast image archive.

“The location in this particularly active region increases the likelihood that the collapsing event is linked to the outburst that occurred in September 2015.”

These finds are only a sample of a number of similar discoveries since the end of the mission, as scientists pore through the more than 76,000 images in the Rosetta archive.

2 comments

Amateur finds moon orbiting comet in Rosetta archive

9:46 am

In mining the Rosetta archive of images of Comet 67P/C-G, an amateur astronomer has discovered a twelve-foot-diameter chunk of material that had broken from the comet and was in orbit around it.

Modelling of the Rosetta images indicates that this object spent the first 12 hours after its ejection in an orbital path around 67P/C-G at a distance of between 2.4 and 3.9 km from the comet’s centre. Afterwards, the chunk crossed a portion of the coma, which appears very bright in the images, making it difficult to follow its path precisely; however, later observations on the opposite side of the coma confirm a detection consistent with the orbit of the chunk, providing an indication of its motion around the comet until 23 October 2015.

While it is not really unusual for their to be small objects in the coma of the the comet, orbiting it, this is apparently the largest so far found. That they missed it initially is also not surprising, considering the amount of data they were gathering in such a short time.

2 comments

All high resolution images from Rosetta now available

8:35 am

The Rosetta science team has now made available to the public all 70,000 images taken by the spacecraft’s high resolution camera.

Between 2014 and 2016, the scientific camera system OSIRIS onboard ESA’s Rosetta spacecraft captured almost 70000 images of comet 67P/Churyumov-Gerasimenko. They not only document the most extensive and demanding comet mission to date, but also show the duck-shaped body in all its facets. In a joint project with the Department of Information and Communication at Flensburg University of Applied Sciences, the Max Planck Institute for Solar System Research (MPS), head of the OSIRIS team, has now published all of these images. The OSIRIS Image Viewer is suited to the needs of both laymen and expert and offers quick and easy access to one of the greatest scientific treasures of recent years.

The Rosetta archive can be found here.

Leave a comment

The changing surface of Comet 67P/C-G

1:33 pm

Changes on Comet 67P/C-G after outburst

More results from this week’s 50th Lunar and Planetary Science Conference in Texas! Two presentations today focused on showing the dramatic changes on the surface of Comet 67P/C-G that were documented by Rosetta. The first focused on the changes produced after massive outbursts during the comet’s closest approach to the Sun. The second documented several more evolutionary changes that changed more slowly.

The image to the right comes from the first paper, and shows the changes that took place on the surface following one massive outburst, with the numbers in red indicating unchanged features between the two photographs.

It appears an entire cliff section has disappeared, replaced by a single large giant boulder. Interestingly there is no obvious vent opening for the outburst. Instead, it appears that the eruption occurred below ground, and merely blasted part of the surface into space. As noted in the paper:

We report here on a third cliff collapse that occurred in the southern hemisphere in the Sobek region [7], which corresponds to the neck region in the 67P’s southern hemisphere. Due to the close alignment of the 67P’s
southern summer solstice with perihelion passage, the southern hemisphere is subjected to higher solar input, resulting in higher levels of activity and more intensive erosion. The location of the collapsing cliff in Sobek is consistent with the inferred source region of one of the strong outbursts [previously reported].

The paper also showed evidence of a large boulder more than a 100 feet across moving several hundred feet over a period of seven months.

The second paper showed various changes in a number of depressions and scarps on the smooth flat surfaces near the narrow neck that connected the comet’s two lobes. Examples of this terrain can be seen in high resolution pictures here and here and here and here.

From this data scientist suggest that the neck region is slowly dissolving away, its material in these flat areas flying away because the neck happens to be a region of low gravity.

Leave a comment

Why jets formed on Comet 67P/C-G

9:02 am

Scientists analyzing the data produced by Rosetta while it was flying in formation with Comet 67P/C-G have determined that the comet’s complex topology acted almost like nozzles to encourage evaporating material to form jets.

The new study shows for the first time that mainly the unusual shape and jagged topography of the comet are responsible for this phenomenon. The researchers analyzed images at different observation geometries of the Hapi region located on the “neck” of the comet, the narrow part connecting its two lobes. In computer simulations, they were able to reproduce these images thus gaining a better understanding of the driving processes.

In particular, two effects proved to be decisive. Some regions on the surface are located at lower altitudes or in the shade. The first rays of sunlight reach them later. In contrast, the frost evaporates particularly efficiently from the early and strongly illuminated regions. In addition, pits and other concave structures virtually concentrate gas and dust emissions – much like an optical lens.

This means that predicting the evaporation patterns on other comets will require first obtaining a detailed map of the surface, showing both its topography and make-up. This also means that any future explorers will first have to send a robot scouting mission so that they can plan a safe arrival during active periods.

One comment

Short movie from Rosetta of Comet 67P/C-G

8:51 am

A search by a Twitter user of the Rosetta archive from its visit to Comet 67P/C-G has produced a very short movie of the comet’s surface.

The bright dots travelling from the top of the frame to the bottom, which look something like snow, are in fact background stars. They have that apparent motion as the spacecraft moves and the comet rotates. The more rapidly moving streaks are thought to be dust particles illuminated by the Sun. There also appear to be a few streaking cosmic rays.

Take a look. The twelve second movie gives a flavor of what it would be like to walk that comet’s surface.

4 comments

The organic dust of Comet 67P/C-G

11:36 am

A study of the dust released by Comet 67P/C-G and captured by Rosetta shows that carbon molecules appear to comprise the comet’s largest component, and that this material is found in the form of very large macromolecules.

As the study shows, organic molecules are among those ingredients at the top of the list. These account for about 45 percent of the weight of the solid cometary material. “Rosetta’s comet thus belongs to the most carbon-rich bodies we know in the solar system,” says MPS scientist and COSIMA team member Dr. Oliver Stenzel. The other part of the total weight, about 55 percent, is provided by mineral substances, mainly silicates. It is striking that they are almost exclusively non-hydrated minerals i.e. missing water compounds. “Of course, Rosetta’s comet contains water like any other comet, too,” says Hilchenbach. “But because comets have spent most of their time at the icy rim of the solar system, it has almost always been frozen and could not react with the minerals.” The researchers therefore regard the lack of hydrated minerals in the comet’s dust as an indication that 67P contains very pristine material.

…The current findings also touch on our ideas of how life on Earth came about. In a previous publication, the COSIMA team was able to show that the carbon found in Rosetta’s comet is mainly in the form of large, organic macromolecules. Together with the current study, it becomes clear that these compounds make up a large part of the cometary material. Thus, if comets indeed supplied the early Earth with organic matter, as many researchers assume, it would probably have been mainly in the form of such macromolecules.

Organic here does not mean life, but is instead used as chemists use it, to mean the molecule includes the element carbon. The results do suggest however that the early solar system had a lot of carbon available, and that much of it was in a relatively pure form available to interact with other elements.

3 comments

Rosetta’s capture of a dust jet from Comet 67P/C-G

9:26 am

Dust jet on Comet 67P/C-G

Cool image time! The Rosetta science team has released images and data gathered in July 2016 when the spacecraft successfully observed a dust outburst erupting from Comet 67P/C-G’s surface. The image on the right, slightly reduced in resolution, shows that outburst.

When the Sun rose over the Imhotep region of Rosetta’s comet on July 3, 2016, everything was just right: As the surface warmed and began to emit dust into space, Rosetta’s trajectory led the probe right through the cloud. At the same time, the view of the scientific camera system OSIRIS coincidentally focused precisely on the surface region of the comet from which the fountain originated. A total of five instruments on board the probe were able to document the outburst in the following hours.

As should be expected, the results did not match the models or predictions. The jet, instigated by water-ice just below the surface turning into gas when heated by the Sun, was much dustier than predicted. They have theories as to why, but it appears that no one likes these theories that much.

One comment

One last image from Rosetta

8:17 am

Rosetta's last image

Engineers reviewing the last bits of telemetry that was transmitted back to Earth by Rosetta just before it crashed on Comet 67P/C-G have discovered one last image of the comet’s surface.

That image is on the right. It is slightly blurred because of the limitations of Rosetta’s camera at this short range, and the incompleteness of the data received.

The image covers an area about a meter across, with a resolution of about two millimeters per pixel.

I imagine this surface is relatively soft, since the gravity holding the comet together is so slight. If you wanted to dig down, you would find it easy digging.

2 comments

The changes seen by Rosetta on Comet 67P/C-G

1:51 pm

A new study released today describes in detail the many changes seen by scientists in the data collected by Rosetta during its two years in close proximity to Comet 67P/C-G.

“We saw a massive cliff collapse and a large crack in the neck of the comet get bigger and bigger,” said El-Maarry. “And we discovered that boulders the size of a large truck could be moved across the comet’s surface a distance as long as one-and-a-half football fields.”

In the case of the boulder, Rosetta’s cameras observed a 282-million-pound (130-million-kilogram), 100-feet-wide (30-meter) space rock to have moved 150 yards (460 feet, or 140 meters) from its original position on the comet’s nucleus. The massive space rock probably moved as a result of several outburst events that were detected close to its original position.

The warming of 67P also caused the comet’s rotation rate to speed up. The comet’s increasing spin rate in the lead-up to perihelion is thought to be responsible for a 1,600-foot-long (500-meters) fracture spotted in August 2014 that runs through the comet’s neck. The fracture, which originally extended a bit longer than the Empire State Building is high, was found to have increased in width by about 100 feet (30 meters) by December 2014. Furthermore, in images taken in June 2016, a new 500- to 1,000-foot-long (150 to 300 meters) fracture was identified parallel to the original fracture.

“The large crack was in the ‘neck’ of the comet — a small central part that connects the two lobes,” said El-Maarry. “The crack was extending–indicating that the comet may split up one day.”

It is almost a shame that Rosetta did not see that break-up. The images would have been breath-taking, and the science learned priceless.

One comment

Comet 67P/C-G slowly breaking apart

5:56 pm

A comparison of Rosetta images before and after Comet 67P/C-G’s close approach to the sun last year found new fractures and an enlargement of older fractures.

The fractures appear to be developing as forces subtly bend the comet to and fro, Stubbe Hviid, a planetary scientist at the German Aerospace Center Institute of Planetary Research in Berlin, reported October 17 in a press conference at a meeting of the American Astronomical Society’s Division for Planetary Sciences. Hviid and colleagues combined maps from Rosetta with computer simulations of all the forces at work within the comet to determine how the cracks develop. They found that the two bulbous ends rock in opposite directions as the comet spins, flexing the neck and creating severe stress. Because the comet isn’t held together strongly — it’s a conglomeration of dust and ice not much stickier than snow, Hviid said — the neck is starting to break. After a few hundred more years, he said, the comet could fold itself in half as the two lobes snap apart and smoosh together.

Leave a comment

The outbursts on Comet 67P/C-G

9:52 am

The Rosetta science team has released a detailed analysis of the jets and outbursts that they observed coming from Comet 67P/C-G during the comet’s close approach to the Sun.

Brief but powerful outbursts seen from Comet 67P/Churyumov–Gerasimenko during its most active period last year have been traced back to their origins on the surface.

In the three months centred around the comet’s closest approach to the Sun, on 13 August 2015, Rosetta’s cameras captured 34 outbursts. These violent events were over and above regular jets and flows of material seen streaming from the comet’s nucleus. The latter switch on and off with clockwork repeatability from one comet rotation to the next, synchronised with the rise and fall of the Sun’s illumination.

By contrast, outbursts are much brighter than the usual jets – sudden, brief, high-speed releases of dust. They are typically seen only in a single image, indicating that they have a lifetime shorter than interval between images – typically 5–30 minutes. A typical outburst is thought to release 60–260 tonnes of material in those few minutes.

They have also released a new image taken by the navigation camera of Rosetta’s September 30th landing zone.

One comment

Rosetta’s last days

10:36 am

The Rosetta team has released a detailed description of what will be happening in the last two weeks of the spacecraft’s mission, leading up to its landing on the comet’s surface on September 30.

Their description of the difficulty of planning maneuvers based on the complex asymmetrical gravitational field of the two-lobed comet nucleus is especially interesting.

One comment

Rosetta’s final descent to Comet 67P/C-G

9:07 am

The Rosetta science team today posted two stories, describing details about the planned final descent of the spacecraft to the surface of Comet 67P/C-G on September 30, ending the mission.

The spacecraft will land in a region dubbed Ma’at that contains several active pits more than 300 feet across and 150 feet deep. This is also where several of the comets dust jets originate.

3 comments

Rosetta finds carbon molecules in comet dust

9:32 am

The Rosetta science team has announced that they have detected very complex carbon molecules in solid dust particles that were released from Comet 67P/C-G.

“Our analysis reveals carbon in a far more complex form than expected,” remarked Hervé Cottin, one of the authors of the paper reporting the result that is published in Nature today. “It is so complex, we can’t give it a proper formula or a name!” The organic signatures of seven particles are presented in the paper, which the COSIMA team say are representative of the two hundred plus grains analysed so far.

The carbon is found to be mixed with other previously reported elements such as sodium, magnesium, aluminium, silicon, calcium and iron. It is bound in very large macromolecular compounds similar to the insoluble organic matter found in carbonaceous chondrite meteorites that have fallen to Earth, but with a major difference: there is much more hydrogen found in the comet’s samples than in meteorites.

But as this kind of meteorite is associated with reasonably well-processed parent bodies such as asteroids, it is reasonable to assume that they lost their hydrogen due to heating. By contrast, comets must have avoided such significant heating to retain their hydrogen, and therefore must contain more primitive material.

Because of the use of the term organics here for these carbon-based molecules, expect a lot of news reports to misreport this discovery and incorrectly announce with great excitement that Rosetta has “discovered life” on Comet 67P/C-G! Among scientists, any carbon molecule is referred to as organic, even if it is entirely inanimate. In this case these molecules are not the result of life, but of carbon’s atomic structure, allowing it to form an infinite variety of molecules with almost any other element.

3 comments

Philae found!

9:24 am

Philae!

Less than a month before Rosetta’s mission ends the spacecraft’s high resolution camera has finally located Philae in its final resting spot on the surface of Comet 67P/C-G.

The images were taken on 2 September by the OSIRIS narrow-angle camera as the orbiter came within 2.7 km of the surface and clearly show the main body of the lander, along with two of its three legs. The images also provide proof of Philae’s orientation, making it clear why establishing communications was so difficult following its landing on 12 November 2014.

The image on the right clearly shows the lander on its side with one leg sticking up, as theorized by the Rosetta engineers based on the small amount of data they had received before Philae went dead. Furthermore, the wide image at the link above shows that the lander landed exactly as predicted by data, up against a wall — in this case a large boulder — which placed it in shadow most of the time.

8 comments

Changes on Comet 67P/C-G

9:24 am

Cool image time! Below the fold are two images taken by Rosetta of the smooth boulder-strewn area on Comet 67P/C-G called Imhotep, which has been featured many times by the Rosetta science team. The image on the left was taken October 26, 2014 soon after the spacecraft’s arrival at the comet. The image on the right was taken August 17, 2016, almost two years later after it had completed its close approach to the Sun. With both images I have cropped them and reduced their resolution to fit here. With the more recent image I have also stretched it horizontally to better match it to the older image.

The point? The giant boulders on this smooth region act as markers so that we can more easily compare the region and see how it has changed with time. The newer image clearly shows a loss of material from the surface, with the depressions in the smooth areas having grown much larger and in some areas much deeper. At the same time, there has been a softening in some of the edges between the lower and higher areas, especially in the middle of the smooth region.

What will happen here in the future? It appears that the smooth area is actually pond of dust that is slowly evaporating away with each close approach to the Sun, leaving behind the solid bedrock pinnacles within it that only appear as boulders because they are mostly buried. Eventually, when the dust is gone, some of those pinnacles will break away as well.
» Read more

2 comments

Rosetta photographs outburst on Comet 67P/C-G

8:35 am

The Rosetta science team today released data and images of a February 19, 2016 outburst on Comet 67P/C-G that the spacecraft was able to photograph, as it happened.

A strong brightening of the comet’s dusty coma was seen by the OSIRIS wide-angle camera at 09:40 GMT, developing in a region of the comet that was initially in shadow. Over the next two hours, Rosetta recorded outburst signatures that exceeded background levels in some instruments by factors of up to a hundred. For example, between about 10:00–11:00 GMT, ALICE saw the ultraviolet brightness of the sunlight reflected by the nucleus and the emitted dust increase by a factor of six, while ROSINA and RPC detected a significant increase in gas and plasma, respectively, around the spacecraft, by a factor of 1.5–2.5.

In addition, MIRO recorded a 30ºC rise in temperature of the surrounding gas. Shortly after, Rosetta was blasted by dust: GIADA recorded a maximum hit count at around 11:15 GMT. Almost 200 particles were detected in the following three hours, compared with a typical rate of 3–10 collected on other days in the same month.

Be sure an look at the animated gif at the link.

One comment

A fine collection of Rosetta images

10:29 am

Comet 67P/C-G

Many cool images! The Rosetta team has released a bunch of very nice images taken of Comet 67P/C-G during August when the spacecraft was flying in close. The image on the right, cropped and reduced in resolution to post here, shows the comet’s large lobe, with the narrow neck to the left. Make sure you check out the full resolution image. It was taken on August 10, 2016 from about 8 miles away, and has a resolution of less than four feet per pixel. If a person was standing there you could just see them!

What I find most fascinating is the incredible curvature of the comet’s surface. The smooth area on the left, dubbed Imhotep (images of which have been posted here previously), has several big boulders on its flat surface. If you stood there, the ground would be down and horizontal. Walk only a short distance and you quickly reach the curving horizon and that flat area would look like a steep slope dropping down behind you. Yet, the boulders do not roll down hill! Walk a short distance more and you begin to enter the neck region, with giant walls rising above you, until you start to walk up them and they become the floor!

5 comments

How Comet 67P/C-G was made

9:06 am

Using the data from Rosetta, scientists have developed a detailed scenario for the birth process that created Comet 67P/C-G.

During its two-year sojourn at Comet 67P/Churyumov–Gerasimenko, Rosetta has revealed a picture of the comet as a low-density, high-porosity, double-lobed body with extensive layering, suggesting that the lobes accumulated material over time before they merged.

The unusually high porosity of the interior of the nucleus provides the first indication that this growth cannot have been via violent collisions, as these would have compacted the fragile material. Structures and features on different size scales observed by Rosetta’s cameras provide further information on how this growth may have taken place.

Earlier work showed that the head and body were originally separate objects, but the collision that merged them must have been at low speed in order not to destroy both of them. The fact that both parts have similar layering also tells us that they must have undergone similar evolutionary histories and that survival rates against catastrophic collision must have been high for a significant period of time.

In other words, the comet’s two lobes formed slowly as separate bodies but always in the same general region, and then moved closer and closer together until they gently merged. Based on this scenario, Comet 67P/C-G had to have formed very early in the solar system, and also was not in the inner solar system — as it is now — when the great early bombardment occurred there about a billion years ago.

One comment

Rosetta says goodbye to Philae

8:35 am

The Rosetta science team has decided to shut off tomorrow the communications equipment the spacecraft uses in its continuing attempts to re-establish communications with its Philae lander.

Switching off the ESS is part of the preparations for Rosetta’s end of mission. By the end of July 2016, the spacecraft will be some 520 million km from the Sun, and will start facing a significant loss of power – about 4W per day. In order to continue scientific operations over the next two months and to maximise their return, it became necessary to start reducing the power consumed by the non-essential payload components on board.

Though until now they have never stopped trying to contact Philae, they have heard nothing since July 2015. Moreover, the recent close sweeps down to the comet’s surface have failed so far to locate the lander. Unless they are holding back the lander’s discovery for a big splash press conference, it appears that we will never known exactly where the lander touched down.

That is, we will never know. Someday, many decades in the future, some asteroid/comet mining operation will show up and find it. I hope at that time they will carefully pack it up and bring it back for humans to admire as a testament to our human ability to push the unknown. Even better, I hope they put it in the “History of Space” museum, located not on Earth but on Mars, built to educate the children of the colonists who are making possible the expansion of humanity out to the stars.

Leave a comment

Rosetta’s landing site chosen

9:29 am

Rosetta's end

The Rosetta science team has chosen the spacecraft’s landing site on Comet 67P/C-G. The picture on the right shows this region, dubbed Ma’at, located on the comet’s smaller lobe. I also note that this decision makes no mention of Philae, and that there has been no word from the scientists on whether their recent close-up imagery of the comet has located the lander.

I had hoped that they would find it and then aim the final descent toward it, but this apparently is not happening.

2 comments
1 2 3 … 7