Tag Archives: Rosetta

Watch: real footage of cosmic particle ‘snow’ on comet 67P

It looks like a winter wonderland scene from an old black and white film but — don’t be fooled — what you’re seeing is real footage from the surface of the comet 67p/Churyumov-Gerasimenko. These images were captured by the European Space Agency’s Rosetta probe over the course of 25 minutes on the 1st of June, 2016, and processed by an awesome human who posted the whole thing on twitter.

The raw images were made with Rosetta’s OSIRIS, or Optical, Spectroscopic, and Infrared Remote Imaging System. What we’re seeing in the foreground is the comet’s surface, as seen by the probe from a distance of several kilometers. In the background, you can see stars belonging to the constellation Canis Major.

What looks like snow here are actually cosmic rays (charged subatomic particles), which register as streaks of light as they hit the camera’s sensor. It’s true, however, that there is some actual snow in the footage — specks of dust and ice.

The Rosetta spacecraft and its lander, Philae, reached 67P in 2014 after a 10-year round-trip journey of four billion miles.  The probe crashed into the comet’s surface in 2016.

Defunct Philae found on the surface of the comet

As Rosetta’s mission draws close to an end, its high-resolution camera snapped a few photos of the Philae lander, wedged into a dark crack on Comet 67P/Churyumov–Gerasimenko.

Can you spot Philae in this picture? Zoomed-in version below. Image via ESA.

In August 2014, the Rosetta spacecraft became the first man-made object to interact with a comet from close range. It performed a series of maneuvers which allowed it to enter the comet’s orbit, and from there made several important observations, transmitting a trove of valuable data back to Earth. But the European mission was even more ambitious than this: they sent a lander to the surface of the comet.

The Philae lander detached from Rosetta on 12 November 2014 but things didn’t go as smoothly as possible. The landing was a bit odd, with Philae failing to launch one of its anchoring harpoons. A thruster designed to hold the probe onto the surface also didn’t fire, and the probe bounced off the surface twice. After this, Philae did manage to land on the comet, but it really wasn’t the optimal land we were hoping for.

The land left it in a less-than-ideal position in a shaded area. Its battery ran out of power 3 days later, and because it lacked access to sunlight it couldn’t really power up again. Rosetta’s communications module with the lander was completely turned off on 27 July 2016 and we’ve known nothing of the probe ever since – it was completely silent.

But now, with one month left of the Rosetta mission, the craft spotted Philae again.

“With only a month left of the Rosetta mission, we are so happy to have finally imaged Philae, and to see it in such amazing detail,” says Cecilia Tubiana of the OSIRIS camera team, the first person to see the images when they were downlinked from Rosetta yesterday.

“After months of work, with the focus and the evidence pointing more and more to this lander candidate, I’m very excited and thrilled that we finally have this all-important picture of Philae sitting in Abydos,” says ESA’s Laurence O’Rourke, who has been coordinating the search efforts over the last months at ESA, with the OSIRIS and Lander Science Operations and Navigation Center (SONC, CNES) teams.

The team had been actively searching for Philae for months, but it wasn’t an easy job. At the camera’s resolution of 5 cm/pixel, this was just barely enough to reveal features of Philae’s 1 m-sized body and its legs, as can be seen in this image.

Philae close-up, labelled. The images were taken from a distance of 2.7 km, and have a scale of about 5 cm/pixel. Philae’s 1 m wide body and two of its three legs can be seen extended from the body.

“This remarkable discovery comes at the end of a long, painstaking search,” says Patrick Martin, ESA’s Rosetta Mission Manager. “We were beginning to think that Philae would remain lost forever. It is incredible we have captured this at the final hour.”

“This wonderful news means that we now have the missing ‘ground-truth’ information needed to put Philae’s three days of science into proper context, now that we know where that ground actually is!” says Matt Taylor, ESA’s Rosetta project scientist.

The discovery comes less than a month before Rosetta descends to the comet’s surface. At the end of this month, on 30 September, Rosetta will be sent on a one-way mission to investigate the comet from close up.


What comet dust looks like, courtesy of ESA’s Rosetta mission

Millions of miles afar, comets dot the night’s sky leaving an unmistakable trail of dust, gas and ice. In 2014, Rosetta’s Philae probe landed on a comet — a monumental achievement in space exploration — documenting the inner workings, chemical composition and structure of these fascinating cosmic bodies. Among others, we now know the 67P/Churyumov–Gerasimenko comet has sinkholes or holds primordial oxygen. Now, researchers revealed a more familiar curiosity: what dust particles on a comet look like.

Diversity of particles seen on a small area on one single target. This image section measures 2.5 mm across, with light coming from the right. Examples of a compact particle (a), a shattered cluster (b), a glued cluster (c) and a large rubble pile (d) are seen in this small area. Image: ESA

Diversity of particles seen on a small area on one single target. This image section measures 2.5 mm across, with light coming from the right. Examples of a compact particle (a), a shattered cluster (b), a glued cluster (c) and a large rubble pile (d) are seen in this small area. Image: ESA

Dust grains were collected between 1 August 2014 – 3 April 2015 across nine 1 cm^2 targets and analyzed using the COSIMA instrument onboard Rosetta. The team led by Yves Langevin of the Institut d’Astrophysique Spatiale at CNRS/University of Paris-Sud, France, characterized the grains by appearance complexity and particle strength.

These images reveal particles from the comet are very diverse in scales ranging from a few  10s of micrometers (Όm) to several 100 Όm.  In general, the dust families can be divided into compact particles or clusters, with the cluster group further subdivided into shattered clusters, glued clusters and rubble piles.

Compact particles are defined as those with well-defined boundaries, more-often-than-not found without any related smaller ‘satellite’ particles. Credit: ESA

Compact particles are defined as those with well-defined boundaries, more-often-than-not found without any related smaller ‘satellite’ particles. Credit: ESA

Shattered cluster Estelle, one of the most tightly-packed shattered clusters identified. It has three major components plus many minor components. The right hand image is the 3D anaglyph. Credit: ESA

Shattered cluster Estelle, one of the most tightly-packed shattered clusters identified. It has three major components plus many minor components. The right hand image is the 3D anaglyph. Credit: ESA

Glued clusters comprise relatively well-defined particles with an overall complex structure including sub-components which appear to be linked together by a fine-grained matrix, giving the appearance of a smooth surface texture.  Credit: ESA

Glued clusters comprise relatively well-defined particles with an overall complex structure including sub-components which appear to be linked together by a fine-grained matrix, giving the appearance of a smooth surface texture. Credit: ESA

Reference: Typology of dust particles collected by the COSIMA mass spectrometer in the inner coma of 67P/Churyumov-Gerasimenko” by Y. Langevin et al is published in the journal Icarus.

We have new data from the Philae lander – it identifies several new organic molecules on Comet 67P, charts internal structure

NASA’s Rosetta mission began with what some would call a streak of bad luck.

After the successful separation procedure, Philae’s anchoring harpoons failed to fire and the 220-lb. (100 kilograms) lander bounced off 67P’s surface, clipped a crater rim and then bounced a second time before finally coming to rest nearly two hours after first making contact with the comet’s surface.

Philae’s landing points on Comet 67P/Churyumov-Gerasimenko on Nov. 12, 2014.

The plan was for it to recharge its power supply using photo-voltaic panels, but the place it eventually landed on was quite shady. The stranded probe transmited preliminary data until its primary battery was depleted (about 60 hours), and then went into hibernation.

The initial observations, published on July 30 in the journal Science, show that the comet is a porous body with a fairly homogeneous interior. It also has a diverse surface that harbors many different carbon-containing organic molecules, the scientists said.

“What really blows my mind is to have this combination of complementary results, allowing us at the same time to ‘feel’ the surface of the comet, very locally, as if we were there, while also getting the bigger picture through the sounding of the cometary interior structure,” Nicolas Altobelli, acting Rosetta project scientist, told Space.com via email.

“The implications of these measurements, and in particular the fairly homogeneous, very porous structure of the interior, will help constrain the formation models of planetesimals in the solar nebula, by a better understanding of the accretion processes,” Altobelli added, referring to the process by which planetary bodies, stars, comets and so on are formed from spacedust.

Not elegant but effective

While the landing definitely had scientists on the edge, in the end it seems to have been a boon in disguise, as it allowed observations of different locations on 67P’s body, in its initial and final landing spots (which have been dubbed Agilkia and Abydos, respectively).

And those two sites are quite different, it turns out. Agilkia’s surface is relatively soft, covered with a layer of granular material about 0.82 feet (0.25 meters) deep, while Abydos is much harder.


Two trajectory reconstructions of the lander’s touchdown.

“Before the landing of Philae, we believed cometary surfaces might be very soft (loose regolith under low gravity). Some colleagues even feared the lander may sink deeply into the surface at touchdown,” Philae project manager Stephan Ulamec, of the German Aerospace Center (DLR), told Space.com via email. “Although we were aware of our limited knowledge, the fact that some of the material is so hard, and that the surface is so heterogen[eous], was indeed a bit surprising.”

Images captured by Philae’s Comet Infrared and Visible Analyser camera, or CIVA, highlight the diversity and complexity of 67P’s surface, showing fractured, boulder-studded terrain with a variety of grain sizes and reflectivity.

The soft layer of “dirt” goes up to 6.5 feet (2 meters) deep in some places on the surface of the comet, and nonexistent in others, suggest images taken from the ROLIS (Rosetta Lander Imaging System) during the probe’s descent.

The images also show a boulder about 16.5 feet (5 m) wide, which is partly surrounded by a depression resembling a “wind tail,” an erosional feature also seen on our planet, and Mars. Another 17 such structures have since been identified by mission scientists, with lengths ranging from 16.5 feet to 100 feet (5 to 30 m). They are caused by particles abrading the surface of the comet during its travels, like an interstellar sandblasting.

Temperatures also vary on the surface from very uncomfortable to extremely uncomfortable, without the thermal balance offered by a thick atmosphere – daytime temperatures on the comet’s surface in November 2014 ranged from minus 226 degrees Fahrenheit to minus 298 degrees Fahrenheit (minus 143 to minus 183 degrees Celsius). However, as the comet is closer to the sun, those temperatures have probably risen by now but the difference between the dark and lighted side is presumed to be higher.

An organic cocktail

Two different Philae instruments, known as Ptolemy and COSAC (Cometary Sampling and Composition), hunted for organic compounds— the building blocks of life as we know it — on and around Comet 67P.

While the initial data burst received from the lander did hint at the existence of organics on its surface, the data was limited and its meaning not very clear.

The new data is much more interesting. Both instruments detected lots of molecules. COSAC, for example, found 16 different organics, including four (methyl isocyanate, acetone, propionaldehyde, and acetamide) that had never been spotted on or around a comet before.

“If such cometary material falls onto a planet in the right environment, emerging life could make use of it,” COSAC principal investigator Fred Goesmann, of the Max Planck Institute for Solar System Research in Germany, told Space.com via email.

Ptolemy’s observations also revealed a rich mix of organics, along with lots of water and carbon dioxide.

“I think an understanding of the organic compounds that are present in this particular comet will have tremendous ramifications for origin-of-life studies,” Ptolemy principal investigator Ian Wright, of the Open University in the United Kingdom, told Space.com.

The newly reported Ptolemy data were gathered during a calibration run, Wright said, adding that more results from the instrument will be published soon.

Internal structure also charted.

Using its CONSERT (Comet Nucleus Sounding Experiment by Radiowave Transmission) instrument, the Rosetta lander also studied the interior structure of the comet. This instrument picks up long-wavelength signals beamed through 67P by the orbiting Rosetta mothership.

Data suggest that the “head” of the comet is homogeneous -on the scale of a few tens of meters- and really porous, with open space making up 75 to 85 percent of its volume, researchers said.

Observations done with this instrument have also narrowed down the area where the lander might be found -we lost it a little– to a ribbon about 69 feet wide by 112 feet long (21 by 34 m).

“Philae provided us unique information on a comet’s surface properties (and interior) that could not be obtained from orbiter measurements alone,” Ulamec said. “We learned so much about comets that now future missions can be adapted in a much better way to this challenging environment.”

And Philae’s not out yet!

The newly released studies are not necessarily the last word from Philae, as the lander woke from hibernation in mid-June.

Communication between Philae and its handlers here on Earth remains extremely spotty — the last contact occurred on July 9 — but the mission team holds out hope that it can get the lander up and running again soon.

“We keep listening and sending commands to Philae, every time we have an opportunity for communication,” Altobelli said.


Rosetta spacecraft finds huge sinkholes on comet’s surface

Rosetta is a robotic space probe built and launched by the European Space Agency. Along with Philae, its lander module, the craft is performing a detailed study of comet 67P/Churyumov–Gerasimenko.

The probe usually orbits 67P at a distance of a few hundred kilometers. Footage received from Rosetta over the last year showed a number of dust jets coming from the comet, which we expected to see. But, after analyzing high-fidelity images from the lander’s OSIRIS instruments, taken just ten to 30 km from the comet’s center, scientists saw that at least some of the dust jets come from specific locations on the comet’s surface, being projected from huge sinkholes.

The scientists have picked out 18 quasi-circular pits in the northern hemisphere of the comet, some of which are still active now. Each sinkhole is anywhere from a few tens of metres to hundreds of metres in diameter and go below the surface by up to 210m to a smooth dust-covered floor.

A catalogue of sinkholes spotted by Rosetta on comet 67P/Churyumov-Gerasimenko.
Image via: forbes.com

“We see jets arising from the fractured areas of the walls inside the pits. These fractures mean that volatiles trapped under the surface can be warmed more easily and subsequently escape into space,” says Jean-Baptiste Vincent from the Max Planck Institute for Solar System Research, lead author of the study.

Similar to the ones on Earth, these sinkholes form when a cavity opens up under the surface. As it widens and deepens, the loss of material makes the ceiling too thin to support its own weight, and collapses. After the collapse, the volatile materials can evaporate or be eroded more easily, and the sinkhole enlarges over time.

“Although we think the collapse that produces a pit is sudden, the cavity in the porous subsurface could have growing over much longer timescales,” says co-author Sebastien Besse, of ESA’s ESTEC technical centre in the Netherlands.

So, what caused these cavities to form in the first place? The team has three theories that they are pursuing.

The first one is that they are artifacts of the comet’s weak gravitational field. When it formed, material accreted by means of low-velocity impacts, leaving behind void areas due to the imperfect fit between primordial building blocks. Over time, seismic events or space impacts cause the surface to weaken enough to cause it to collapse.

Another possibility is that the pits are full of volatile ices like carbon dioxide and carbon monoxide, sitting just beneath a layer of dust. These ices could be melted by the warmth of the Sun as the comet draws closer in its orbit every year.

Or it could be that the ice manages to melt itself away by transforming from amorphous ice made up of irregularly packed molecules to crystallised ice, a process that would release heat which could be sufficient to cause evaporation.

Close-up photo of sinkholes on 67P.
Image via: esa.int

“Regardless of the processes creating the cavities, these features show us that there are large structural and/or compositional differences within the first few hundred metres of the comet’s surface and the cavities are revealing relatively unprocessed materials that might not otherwise be visible,” says Besse.

Researchers analyzing the interior structure of the sinkholes found that their interiors differ quite significantly, with some showing fractured material and terraces, others showing horizontal layers and vertical striations and others also showing globular structures nicknamed “goosebumps”.

“We think that we might be able to use the pits to characterise the relative ages of the comet’s surface: the more pits there are in a region, the younger and less processed the surface there is,” explains Vincent. “This is confirmed by recent observations of the southern hemisphere: this is more highly processed because it receives significantly more energy than the northern hemisphere, and does not seem to display similar pit structures.”

Active pits on Churyumov-Gerasimenko.

Rosetta scientists are hopeful that the spacecraft might yet get to see the formation of a sinkhole in action. The probe did see one outburst during its approach to the comet back in April 2014, which generated between 1,000kg and 100,000kg of material. But although a pit collapse could have been responsible for this, it was much smaller than the researchers expect.

With the collapse of a typical large pit of 140m wide and 140m deep, the team would expect to see the release of around a billion kilograms of material.

“Being able to observe changes in the comet, in particular linking activity to features on the surface, is a key capability of Rosetta and will help us to understand how the comet’s interior and surface have evolved since its formation. And with the extension of the mission until September 2016, we can do the best job possible at unravelling how comets work” says Matt Taylor.




Water didn’t come from comets, Rosetta analysis shows

As you might remember, a few days ago we were telling you about the fantastic success of the Rosetta mission – a spacecraft launched by the European Space Agency which orbited a comet and sent landed a probe on it. Now, we already have the first result: Earth’s water probably didn’t come from comets.

Rosetta’s extremely interesting analysis raises even more questions than it answers. Image via ESA.

Did you ever ask yourself where did the Earth’s oceans come from? In its initial protoplanetary stage, the Earth was very hot so of course, there couldn’t be any water on its surface; so the water came at a later stage, but from where? Many researchers actually believe that Earth was “inseminated” with water from outer space – either from asteroids or comets. Now, a new chemical analysis based on data from the Rosetta mission shows that water almost certainly didn’t come from comets.

“We have to conclude… the terrestrial water was brought by asteroids more likely than comets,” said Kathrin Altwegg, principal investigator on the ROSINA mass spectrometer that has been examining the chemical fingerprint of water and other gases in the comet.

A comet is an icy small body from the Solar System, while asteroids are considered to be minor planets. There are certainly many similarities between comets and asteroids, but there are also significant differences. The first one is composition: while comets are made from ice, dust, some rocky materials and organic compounds, asteroids are rocky. For this reason, when they get closer to the sun, comets lose material, while asteroids typically remain solid.

Both asteroids and comets are remnants from the initial period of the solar system – you can consider them left over building blocks. So if you study them, you can get a glimpse of how the solar system looked in the past; not only that, but you can also see if the Earth’s water came from them or not. As it turns out, it didn’t come from comets, but that only makes things even more interesting,

“We found something different,” says Altwegg, and “more exciting.” She heads the team operating a spectrometer aboard Rosetta, which is circling in orbit some 14 miles (23 kilometers) above comet 67P.

With a spectrometer an instrument which measures spectral properties and can be used to identify materials and chemical compositions, researchers measured the amount of deuterium, a heavier isotope of hydrogen, found in the ice on the surface of the comet. This chemical make-up is significantly different from the one on Earth, so it means that the water here has another source. This leaves asteroids as the likely culprits, but raises even more questions about comets.

“It is a very exciting study that raises more questions than it answers,” says geophysicist Nicolas Dauphas of the University of Chicago, who was not part of the discovery team. “The mission is a tremendous success for space exploration and for science in Europe.”

However, some experts are not convinced, citing the low number of studied comets. Not all comets are the same, and different studies may yield different results.

“Each comet is different, and the question of their contribution to Earth’s atmosphere and oceans is still open,” Dauphas says.

The problem is even more complex – comets are indeed fewer than asteroids in our solar system (4,000 vs 650,000), but they contain water, while many asteroids don’t. Francis Rocard, a Rosetta scientist at the France’s National Center for Space Studies (CNES) also agrees that things seem even more complicated in the light of recent findings.

“To me, these findings do not shake things up but render them a bit more complex than we previously believed, all while reinforcing the hypothesis that asteroids are the source of Earth’s water,” he told AFP.

Results were published in Science.

Comet 67 full colour

First full colour image of Comet 67P captured by Rosetta probe; meanwhile, Philae lost a leg

Only a couple of weeks ago, a historic rendezvous between the Rosetta spacecraft and Comet 67P was made after a 10-year round-trip journey of four billion miles. Most importantly, the Rosetta deployed its lander, Philae, safely on the comet’s surface which is set to soon beam back important information pertaining to the comet’s inner composition and other details. For instance, we already know there are organic molecules on the comet, a find that has great implications for planetary formation theory as well as alien life. Now, we’re all in for a treat – a ‘true’ colour photo of the comet taken by Rosetta.

Comet 67P, now in colour

Comet 67P/Churyumov-Gerasimenko by Rosetta's OSIRIS narrow-angle camera on 3 August 2014 from a distance of 285 km. The image resolution is 5.3 metres/pixel. Credit: ESA/Rosetta/MPS

Comet 67P/Churyumov-Gerasimenko by Rosetta’s OSIRIS narrow-angle camera on 3 August 2014 from a distance of 285 km. The image resolution is 5.3 metres/pixel.
Credit: ESA/Rosetta/MPS

The press has shown so many artsy black and white photos of 67P that one might fall for it and believe that’s how the comet really looks like. Besides the Navcam, which can only capture images in grey-scale, Rosetta has another optical instrument called OSIRIS  – a dual imaging system operating in the visible, near infrared and near ultraviolet wavelength ranges. It too lacks colour sensors, but makes up for it with filter wheels which allow for the imaging of wavelengths in red, green and blue. When each frequency is combined, a true colour image can be built.

“We’ve seen crags, its weird kidney shape and all sorts of dramatic shadows playing across the comet’s surface. One thing all those images have in common is that they’re in stark, artsy black and white,” said Amanda Kooser. “This leaves us with a curious question: what does 67P look like in color?”

Imaged below is Comet 67P as it really looks like: reddish-brown. It’s important to note that the image was doctored to make up for blurs resuling from an offset between exposure times for each of the three frequencies.

Comet 67 full colour

Image Credit: ESA/AGU

According to the report authors, “the full nucleus will be mapped at multiple resolutions” and the mapping “will include imaging using the full spectral range of
 the OSIRIS imaging system (245nm to 1000nm in 11 optical filters). The color mapping will be done under good illumination condition at ~1m/pixel as part of the pyramid arc approach phase. This will later be followed by higher resolution imaging (down to 20 cm/pixels) of parts of the nucleus.”

“Rosetta’s comet will continue to be a source of fascination,” Kooser added. “Whether this image depicts what the comet would look like if you happened to be looking at it while riding on Rosetta, it definitely offers up a new perspective on our previously gray-scale viewpoint.”

A one leg short lander

In other news, the Philae lander may could become operational as early as March 2015. Currently, it landing probe is offline since it receives only one hour of sunshine a day – far too little energy to power its communications or heat the batteries, for that matter, which are now frozen in temperatures of -170 degrees Celsius. The lander bounced several times off the comet before landing, and its location is current unknown. Russian scientists believe, however, that it may have scraped a crater with one of its legs during landing, according to magnetic field data from the Rosetta Lander Magnetometer and Plasma Monitor (ROMAP).  The scrape may have sent the lander spinning away from its intended landing site.

“It was not a touchdown like the first one, because there was no signature of a vertical deceleration due to a slight dipping of our magnetometer boom as measured during the first and also the final touchdown,” ROMAP co-principal investigator Hans-Ulrich Auster said in a statement. “We think that Philae probably touched a surface with one leg only — perhaps grazing a crater rim — and after that the lander was tumbling.”


Artist's impression of the Rosetta spacecraft flying past an asteroid. Photograph: AP

Rosetta Illustrates the Miracles of Space Science

This is an article by Dave Syndergaard, professor in the Space Studies program at the American Public University.


That’s the first word that comes to my mind when I think about the European Space Agency (ESA) mission to Comet 67P/Churyumov-Gersimenko. The Rosetta spacecraft and its lander, Philae, recently reached 67P after a 10-year round-trip journey of four billion miles.

 Artist's impression of the Rosetta spacecraft flying past an asteroid. Photograph: AP

Artist’s impression of the Rosetta spacecraft flying past an asteroid. Photograph: AP

Here’s where the “miracles” come in:

Miracle number one: Mission planners had to calculate a circuitous journey for Rosetta that included four fly-by’s of major planets, which increased its speed enough to reach the comet. Think of a 10-year, four billion mile journey that included zipping past planets and asteroids and culminated in getting close enough to the four-mile- wide comet to go into orbit around it and drop a lander on its surface.

The math and physics involved in rendezvous and proximity operations are daunting. Even though we’ve gotten pretty good at it since the first space rendezvous operations were conducted in the mid-1960s,  it had never been attempted before from this distance or with this oddly-shaped an object.

While 67P is a comparatively small rubble pile in space, it’s massive enough for its gravity to have an effect on both Rosetta and Philae. This means that scientists had to calculate and recalculate its mass and center of mass in real-time from Rosetta as they brought the spacecraft closer to the comet.


Miracle number two: On June 8, 2011, after Rosetta zipped past asteroids 2867 Steins (September 5, 2008) and 21 Lutetia (July 10, 2010), mission managers put it into hibernation to conserve electrical power. Rosetta flew past the orbit of Jupiter, where sunlight is less than four percent of that on Earth.  For 31 months, it conserved power by not communicating with the Earth at all and generated only enough heat to keep the craft and its instruments from freezing.

Rosetta delivered a tiny amount of electricity to an alarm clock of sorts that roused the spacecraft from its sleep right on schedule on January 20, 2014. The scientists and engineers who were waiting for that signal had to believe that the spacecraft would be exactly where they had calculated it would be and that it would still be in working order.

Miracle number three: Touchdown. Starting in May, mission controllers conducted an intricate set of nine thruster burns that brought Rosetta alongside 67P on August 6.  About 60 miles from 67P, Rosetta fired its thrusters and entered orbit. After that, mission controllers decreased the orbital altitude to a final circular orbit around the asteroid at 12 miles above the surface.

On November 12, the 220-pound Philae lander, which had been attached to Rosetta’s side since launch, separated from Rosetta and descended for seven hours (without propulsion or guidance) and touched down on the surface of 67P. Bear in mind that Rosetta and Comet 67P are hurtling through space at approximately 41,000 miles per hour in an elliptical orbit around the sun.

Kepler’s Laws tell us the orbital velocity is constantly changing and increasing as 67P and Rosetta approach the sun. It’s no exaggeration to say that landing Philae on the surface of 67P was like landing a speeding bullet on another speeding bullet.

The Philae lander landed in the shadow of a cliff.  As a result, the lander’s solar panels aren’t receiving enough of the Sun’s energy, and Philae has powered down. Before it lost power, the lander sent back several exciting images as well as very useful science data. Just before they lost contact with Philae, mission controllers lifted and rotated the lander’s body in an attempt to receive more solar energy. The Rosetta team is confident that when the comet and lander get closer to the Sun, Philae’s solar panels will receive enough energy to allow the lander to power up and continue its mission.

Obviously this accomplishment was not, in fact, a miracle, but the culmination of hard work, expertise, determination, and checking and double-checking. All of this was done by men and women who once sat in undergraduate space studies classes dreaming of someday making a major contribution to science. That’s miraculous and inspiring.

Editor’s note:  Before Philae went offline, it relayed that it had found carbon molecules on the comet’s surface, a discovery with significant implications to the origin of life. 

Rosetta’s Philae probe landed on a comet – why this is HUGE news

OK, so we’ve been keeping you up to date with what’s been happening with the Rosetta mission, but we had to sleep eventually, and wonderful things have happened in the mean time. In case you’re not aware, here’s a short summary: Rosetta is a probe launched by the European Space Agency (the European equivalent of NASA) in order to study a comet. Rosetta has been orbiting the comet for a while, took some breathtaking pictures, and eventually sent a lander towards the probe. There have been some technical issues, but in a stunning achievement, Philae, the lander, managed to attach itself to the comet! Here’s why this is a big deal.

First image from the surface of Comet 67P/Churyumov-Gerasimenko from the Rosetta million’s lander Philae Photograph: ESA/Rosetta/Philae/CIVA/Photograph: ESA/Rosetta/Philae/CIVA

First of all, the technical achievement is spectacular. It’s the first time humans have landed anything on a comet. Comets have negligible gravity so it’s hard to establish an orbit around comets. Also, landing there is difficult because there’s a risk of the lander simply bouncing off the surface of the comet. Comets are also very mobile, with often irregular orbits, bringing even more problems to the table.

Comets are icy remnants which took shape in the initial phases of the solar system. Studying the composition of comets might yield important information about the birth of the solar system. Also, many researchers believe that comets are the initial source of water on our planet. While it is possible that some water was released from the Earth’s interior at this time, comets are a likely source of initial water. The mission could confirm or infirm this theory.

Photo credit: Matt Wang, Flickr: anosmicovni. European Space Agency. Comet 67P/Churyumov–Gerasimenko Relative to Downtown Los Angeles

Rosetta has a wide array of machines onboard, including spectrographs, mass-spectrometers, microscopes and plasma sensors. But there is only so much information which can be gathered without actually landing on the comet – an this is where Philae enters the scene.

After successfully detaching itself from Rosetta, Philae spent 7 hours gracefully dancing its way towards the surface of the comet. Not everything went smoothly at the land, as Lander project manager Stephan Ulamec has told the BBC’s Jonathan Amos:

“We are still not anchored. We are sitting with the weight of the lander somehow on the comet. We are pretty sure where we landed the first time, and then we made quite a leap. Some people say it is in the order of 1 km high. And then we had another small leap, and now we are sitting there, and transmitting, and everything else is something we have to start understanding and keep interpreting.”

Assuming success, a scientific trove awaits; the comet has already surprised researchers several times, and there is no telling what other things we will find about our solar system. Some experiments are already underway, as scientists from the Open University explain:

The first experiment, CIVA-P, consists of seven identical cameras that will produce a panoramic image of the comet as seen from Philae. CIVA-P will characterise the landing site, mapping the surface topography and the albedo (reflectivity) of the surface. Two of the camera are aligned so as to produce stereoscopic images.

The mission is even more laudable thanks to its efficiency – it cost European citizens a mere 3.5 euro to conduct this mission – even less than a cinema ticket.


Rosetta comet landing – watch it as it happens! [live blog]

In case you’re not aware, the European Space Agency is just now trying to send Rosetta’s lander, Philae, towards the comet 67P/Churyumov–Gerasimenko. The probe is already orbiting the comet and has revealed the most accurate topography of a comet. Watch the live stream here:

Further updates: The separation went great, and the lander is on its way to the comet.

09:06 GMT. Philae is now on its way to the Rosetta comet, everybody is glad that it worked flawlessly. There are still many more crucial moments (the most important one a few hours from now), but so far, everything is just fine.

09:04 GMT. Success! The separation appears to have been successful.

09:00 GMT. We are just moments away from finding out if the separation was successful!

08:59 GMT.Rosetta’s trajectory:

After it has deployed Philae, it will manoeuvre away to keep Philae and the landing site in view. Illustration: Esa

08:44 GMT. The separation has already taken place… hopefully. However, there’s no way for us to know until the signal reaches Earth. At t he moment, several astronomers are discussing the project on the stream.

08:39 GMT. In case you would like to send comments or questions to the people working at the ESA, use: #cometlanding.

The Rosetta is currently working on its ‘pre-separation manoeuvre’. This is a thruster burn to place it on course for the separation point, when it will release Philae. There are, however, significant problems. The cold gas thruster seems to not work properly, and without the thruster, the risk of Philae bouncing off the surface of the comet has increased. However, all other devices are working properly, so the team decided to go ahead and rely on three screws and two harpoons to drill the legs to the surface of the comet.

08:34 GMT. Overnight, there have been two more go/nogo decisions. Both were ‘go’ but the Philae lander team needed an additional hour before they confirmed that they were indeed ‘good to go’. Right now, we are at a point of no going back, and as I am writing this, we will see the separation about 30 minutes from now. Well, actually, it is happening NOW, but because the distance between Earth and the comet is so large, it will take the signal almost 30 minutes to reach Earth.

08:20 GMT. It’s a very risky mission, landing something on a comet. It’s the first time something like this has been attempted.


Artistic depiction of Philae landing on the comet. Image credits: ESA.

Professor Ian Wright at The Open University is the Principal Investigator for the Ptolemy instrument on board the Rosetta mission. He is in Darmstadt at the moment. You can watch a video of Wright answering questions about the Rosetta mission here: