67P Archives

January 24, 2015December 23, 2015 by Tim Reyes

There’s a Crack Forming on Rosetta’s 67P. Is it Breaking Up?

A Fissure spanning over 100 meters across the neck of Rosetta's comet 67P raises the question of if or when will the comet breakup. The fissure is part of released studies by Rosetta scientists in the Journal Science (Image Credits: ESA/Rosetta, Illustration, T.Reyes)

Not all comets break up as they vent and age, but for Rosetta’s comet 67P, the Rubber Duckie comet, a crack in the neck raises concerns. Some comets may just fizzle and uniformly expel their volatiles throughout their surfaces. They may become like puffballs, shrink some but remain intact.

Comet 67P is the other extreme. The expulsion of volatile material has led to a shape and a point of no return; it is destined to break in two. Songwriter Neil Sedaka exclaimed, “Breaking Up is Hard to Do,” but for comets this may be the norm. The fissure is part of the analysis in a new set of science papers published this week.

Top left: The Hathor cliff face is to the right in this view. The aligned linear structures can be clearly seen. The smooth Hapi region is seen at the base of the Hathor cliff. Boulders are prevalent along the long axis of the Hapi region. Bottom left and right: Crack in the Hapi region. The left panel shows the crack (indicated by red arrows) extending across Hapi and beyond. The right panel shows the crack where it has left Hapi and is extending into Anuket, with Seth at the uppermost left and Hapi in the lower left. (Credit: ESA/Rosetta)

The images show a fissure spanning a few hundred meters across the neck of the two lobe comet. The fissure is just one of the many incredible features on Comet 67P and is reported in research articles released in the January 22, 2015, edition of the journal Science.

What it means is not certain, but Rosetta team scientists have stated that flexing of the comet might be causing the fissure. As the comet approaches the Sun, the solar radiation is raising the temperature of the surface material. Like all materials, the comet’s will expand and contract with temperature. And diurnal (daily) changes in the tidal forces from the Sun is a factor, too.

An image sequence from the Navcam of the Rosetta spacecraft (right) is shown beside a simulation. Further work on the interaction of comets with solar radiation will include computer models that utilize Rosetta data to reveal how comet nuclei evolve over time – over many orbits of the Sun- and break up. Peanut, rubber-duck, potatoes or just round-shaped comet nuclei likely result from combinations of rotation, changes in rotation, spin rate, composition and internal structure, as a nucleus interacts with the Sun over many orbits. (Credits: ESA/Rosetta, Illustration – J.Schmidt)

The crack, or fissure, could spell the beginning of the end for comet 67P/Churyumov–Gerasimenko. It is located in the neck area, in the region named Hapi, between the two lobes that make 67P appear so much like a Rubber Duck from a distance. The fissure could represent a focal point of many properties and forces at work, such as the rotation rate and axis – basically head over heels of the comet. The fissure lies in the most active area at present, and possibly the most active area overall. Though the Hapi region appears to receive nearly constant sunlight, at this time, Rosetta measurements (below) show otherwise – receiving 15% less sunlight than elsewhere.

Left: A map looking at the northern (right-hand rule, positive) pole of 67P showing the total energy received from the Sun per rotation on 6 August 2014. The base of the neck (Hapi) receives ~15% less energy than the most illuminated region, 3.5 × 106 J m-2 (per rotation). If self-heating were not included, the base of the neck would receive ~30% less total energy. Right: Similar to the left panel but showing total energy received over an entire orbital period in J m-2 (per orbit). (Credit:ESA/Journal Science Article, Figure 5) — Left: A map looking at the northern (right-hand rule, positive,) pole of 67P showing the total energy received from the Sun per rotation on 6 August 2014. The base of the neck (Hapi) receives ~15% less energy than the most illuminated region, 3.5 × 106 J m-2 (per rotation). If self-heating were not included, the base of the neck would receive ~30% less total energy. Right: Similar to the left panel but showing total energy received over an entire orbital period in J m-2 (per orbit). (Credit:ESA/Journal Science Article, Figure 5)

Sunlight and heating are major factors and the neck likely experiences the greatest mechanical stresses – internal torques – from heating or tidal forces from the sun as it rotates and approaches perihelion. Rosetta scientists are still not certain whether 67P is two bodies in contact – a contact binary – or a shape that formed from material expelled about the neck area leading to its narrowing.

Fragmentation of comets is common. Many sungrazers are broken up by thermal and tidal stresses during their perihelions. At top, an image of the comet Shoemaker-Levy 9 (May 1994) after a close approach with Jupiter which tore the comet into numerous fragments. An image taken by Andrew Catsaitis of components B and C of Comet 73P/Schwassmann–Wachmann 3 as seen together on 31 May 2006 (Credit: NASA/HST, Wikipedia, A.Catsaitis) — Fragmentation of comets is common. Many sungrazers are broken up by thermal and tidal stresses during their perihelions. At top, an image of the comet Shoemaker-Levy 9 (May 1994) after a close approach with Jupiter which tore the comet into numerous fragments. An image taken by Andrew Catsaitis of components B and C of Comet 73P/Schwassmann–Wachmann 3 as seen together on 31 May 2006 (Credit: NASA/HST, Wikipedia, A. Catsaitis)

The Philae lander’s MUPUS thermal sensor measured a temperature of –153°C (–243°F) at the landing site, while VIRTIS, an instrument on the primary spacecraft Rosetta, has measured -70°C (-94°F) at present. These temperatures will rise as perihelion is reached on August 13, 2015, at a distance of 1.2432 A.U. (24% further from the Sun than Earth). At present – January 23rd – 67P is 2.486 A.U. from the Sun (2 1/2 times farther from the Sun than Earth). While not a close approach to the Sun for a comet, the Solar radiation intensity will increase by 4 times between the present (January 2014) and perihelion in August.

Hubble capture a sequence of images of the comet 73P/Schwassman-Wachmann 3. The comet fragmented and like 73P, Rosetta's 67P will likely breakup some day in two majore fragments with debris spreading out as in these images. The Solar wind pressure as well as any explosive force from the breakup causes the comet fragments to slowly disperse but altogether remain effectively in the same orbit. (Image Credit: NASA/Hubble) — Hubble captured a sequence of images of the comet 73P/Schwassman-Wachmann 3. The comet fragmented, and like 73P, Rosetta’s 67P will likely break some day into two major fragments with debris spreading out as in these images. The Solar wind pressure, as well as any explosive force from the break up, will cause the comet fragments to slowly disperse but effectively remain in the same orbit. (Image Credit: NASA/Hubble)

Stresses due to temperature changes from diurnal variations, the changing Sun angle during perihelion approach, from loss of material, and finally from changes in the tidal forces on a daily basis (12.4043 hours) may lead to changes in the fissure causing it to possibly widen or increase in length. Rosetta will continue escorting the comet and delivering images of the whole surface that will give Rosetta scientists the observations and measurements to determine 67P/Churyumov–Gerasimenko’s condition now and its fate in the longer term.

The fissure is not a very recent event. Universe Today's Bob King published an earlier image in his blog in September and added a question to illustrate. Whether the crack has widen since this time is not certain. (Image Credit: ESA, Illustration, Bob King) — The fissure is not a very recent event. Universe Today’s Bob King published an earlier image in his blog in September and added a question to illustrate. Whether the crack has widened since that time is not certain. (Image Credit: ESA, Illustration, Bob King)

Stay tuned for a forthcoming article from UT’s writer Bob King about numerous Rosetta mission scientific findings published this week in the journal Science.

Reference:

The morphological diversity of comet 67P/Churyumov-Gerasimenko

On the nucleus structure and activity of comet 67P/Churyumov-Gerasimenko

January 21, 2015December 23, 2015 by Jason Major

Rosetta Gets a Peek at Comet 67P’s “Underside”

Four-image mosaic of 67P/Churyumov-Gerasimenko acquired on Jan. 16, 2015 (ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0)

A particularly dramatic view of comet 67P/C-G due to the angle of solar illumination, this is a mosaic made from four images acquired by Rosetta’s NavCam on January 16, 2015, from a distance of 28.4 km (17.6 miles). The assembled image shows the larger “bottom” lobe of 67P, with a flat region called Imhotep along the left side and, on the lower right, the transition area stretching up to the comet’s smaller “head” lobe. Outgassing jets can be seen as faint streaks at the upper right, and ejected dust grains show up as bright specks above its surface.

Also in this view is one of 67P’s larger boulders, a somewhat pyramid-shaped rock dubbed “Cheops.” Can you spot it?

There it is!

Position of the Cheops boulder on 67P (ESA/Rosetta/Navcam)

One in a cluster of boulders on 67P’s “underside,” Cheops is about 45 meters wide and 25 meters high (148 x 82 feet).

When it was first observed in Rosetta images Cheops and the nearby cluster reminded scientists of the pyramids at Giza in Egypt, and so it was named for the largest of those pyramids, the Great Pyramid, a tomb for the pharaoh Cheops (the Hellenized name for Khufu) built around 2,550 BCE. (See another view of the Cheops cluster here.)

OSIRIS image of Cheops acquired on Sept. 19, 2014 (ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

Scientists are still working to determine the nature of 67P’s boulders. It’s not yet known what they are made of or how they came to be where they are observed today. Did they fall into their current positions? Or were they exposed upwards from below as a result of the comet’s activity? And why do they have alternating rough and smooth areas on their surfaces?

“It almost looks as if loose dust covering the surface of the comet has settled in the boulder’s cracks. But, of course, it is much too early to be sure,” said OSIRIS Principal Investigator Holger Sierks from the Max Planck Institute for Solar System Research (MPS) in Germany.

Also see: A Stunning Look at the Cliffs of Comet 67P/Churyumov-Gerasimenko

As comet 67P approaches perihelion over the course of the next six months we will get to see firsthand via Rosetta what sorts of changes occur to its surface features, including office-building-sized boulders like Cheops.

Also, for a quick look at some of 67P’s “vital stats” click here. (Added 1/22)

Source: ESA Rosetta blog

December 11, 2014December 23, 2015 by Tim Reyes

Rosetta’s Instruments Direct Scientists to Look Elsewhere for the Source of Earth’s Water

Illustration of a rocky planet being bombarded by comets. (Image credit: NASA/JPL-Caltech)

Where did all of our water come from? What might seem like a simple question has challenged and intrigued planetary scientists for decades. So results just released by Rosetta mission scientists have been much anticipated and the observations of the Rosetta spacecraft instruments are telling us to look elsewhere. The water of comet 67P/Churyumov-Gerasimenko does not resemble Earth’s water.

Because the Earth was extremely hot early in its formation, scientists believe that Earth’s original water should have boiled away like that from a boiling kettle. Prevailing theories have considered two sources for a later delivery of water to the surface of the Earth once conditions had cooled. One is comets and the other is asteroids. Surely some water arrived from both sources, but the question has been which one is the predominant source.

There are two areas of our Solar System in which comets formed about 4.6 billion years ago. One is the Oort cloud far beyond Pluto. Everything points to Comet 67P’s origins being the other birthplace of comets – the Kuiper Belt in the region of Neptune and Pluto. The Rosetta results are ruling out Kuiper Belt comets as a source of Earth’s water. Previous observations of Oort cloud comets, such as Hyakutake and Hale-Bopp, have shown that they also do not have Earth-like water. So planetary scientists must reconsider their models with weight being given to the other possible source – asteroids.

The question of the source of Earth’s water has been tackled by Earth-based instruments and several probes which rendezvous with comets. In 1986, the first flyby of a comet – Comet 1P/Halley, an Oort cloud comet – revealed that its water was not like the water on Earth. How the water from these comets –Halley’s and now 67P – differs from Earth’s is in the ratio of the two types of hydrogen atoms that make up the water molecule.

Illustration of the Rosetta spacecraft showing the location of the ROSINA mass spectrometer instrument, DFMS. The difference between a Deuterium and Hydrogen atom are also illustrated. A water molecule with Deuterium is known as heavy water due to the additional mass of D vs. H (an extra neutron). (Credit: ESA/Rosetta) — Illustration of the Rosetta spacecraft showing the location of the ROSINA mass spectrometer instrument, DFMS. The difference between a Deuterium and Hydrogen atom is also illustrated. A water molecule with Deuterium is known as heavy water due to the additional mass of Dueterium vs. Hydrogen (i.e., an extra neutron). (Credit: ESA/Rosetta)

Measurements by spectrometers revealed how much Deuterium – a heavier form of the Hydrogen atom – existed in relation to the most common type of Hydrogen in these comets. This ratio, designated as D/H, is about 1 in 6000 in Earth’s ocean water. For the vast majority of comets, remote or in-situ measurements have found a ratio that is higher which does not support the assertion that comets delivered water to the early Earth surface, at least not much of it.

Most recently, Hershel space telescope observations of comet Hartley 2 (103P/Hartley) caused a stir in the debate of the source of Earth’s water. The spectral measurements of the comet’s light revealed a D/H ratio just like Earth’s water. But now the Hershel observation has become more of an exception because of Rosetta’s latest measurements.

A plot displaying the Deuterium/Hydrogen (D/H) ratio of Solar System objects. Only asteroids have a D/H ratio that matches the Earths and comets with the exception of two so far measured have higher ratios. Objects are grouped by color. Planets & moons (blue), chrondritic meteorites from the asteroid belt (grey), Oort cloud comets(purple), Jupiter family comets(pink). Diamond markers = In Situ measurements, Circles = remote astronomical measurements(Credit: Altwegg et al. 2014) — A plot displaying the Deuterium/Hydrogen (D/H) ratio of Solar System objects. Asteroids have a D/H ratio that matches that of the Earth, while comets – except for two measured to date – have higher ratios. Objects are grouped by color: planets & moons (blue), chrondritic meteorites from the asteroid belt (grey), Oort cloud comets (purple), and Jupiter family comets (pink). Diamond markers = In Situ measurements; circles = remote astronomical measurements. (Credit: Altwegg, et al. 2014)

The new measurements of 67P were made by the ROSINA Double Focusing Mass Spectrometer (DFMS) on board Rosetta. Unlike remote observations using light which are less accurate, Rosetta was able to accurately measure the quantities of Deuterium and common Hydrogen surrounding the comet. Scientists could then simply determine a ratio. The results are reported in the paper “67P/Churyumov-Gerasimenko, a Jupiter Family Comet with a high D/H ratio” by K. Altwegg, et al., published in the 10 December 2014 issue of Science.

New Rosetta mission findings do not exclude comets as a source of water in and on the Earth's crust but does indicate comets were a minor contribution. A four-image mosaic comprises images taken by Rosetta’s navigation camera on 7 December from a distance of 19.7 km from the centre of Comet 67P/Churyumov-Gerasimenko. (Credit: ESA/Rosetta/Navcam Imager) — New Rosetta mission findings do not exclude comets as a source of water in and on the Earth’s crust but does indicate comets were a minor contribution. A four-image mosaic comprises images taken by Rosetta’s navigation camera on 7 December from a distance of 19.7 km from the centre of Comet 67P/Churyumov-Gerasimenko. (Credit: ESA/Rosetta/Navcam Imager)

The ROSINA instrument observations determined a ratio of 5.3 ± 0.7 × 10^-4, which is approximately 3 times the ratio of D/H for Earth’s water. These results do not exclude comets as a source of terrestrial water but they do redirect scientists to consider asteroids as the predominant source. While asteroids have much lower water content compared with comets, asteroids, and their smaller versions, meteoroids, are more numerous than comets. Every meteor/falling star that we see burning up in our atmosphere delivers a myriad of compounds, including water, to Earth. Early on, the onslaught of meteoroids and asteroids impacting Earth was far greater. Consequently, the small quantities of water added delivered by each could add up to what now lies in the oceans, lakes, streams, and even our bodies.

References:

D/H Ratio of Water on Earth Measured with DFMS

67P/Churyumov-Gerasimenko, a Jupiter family comet with a high D/H ratio

Rosetta fuels the debate on the Origin of Earth’s Water

The Provenances of Asteroids, and Their Contributions to the Volatile Inventories of the Terrestrial Planets

Recent Universe Today related article:

What Percent of Earth is Water?

December 5, 2014December 29, 2015 by Fraser Cain

Weekly Space Hangout – Dec. 5, 2014: Orion’s Successful Launch!

Host: Fraser Cain (@fcain)

Guests:
Morgan Rehnberg (cosmicchatter.org / @cosmic_chatter)
Ramin Skibba (@raminskibba)

Continue reading “Weekly Space Hangout – Dec. 5, 2014: Orion’s Successful Launch!”

October 15, 2014December 23, 2015 by Jason Major

Here’s a High-Res Look at Philae’s Landing Spot

Mosaic of OSIRIS images of landing site "J" on Comet 67P/CG. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

The long-awaited deployment of the Philae lander, currently “piggybacked” aboard ESA’s Rosetta spacecraft orbiting the nucleus of Comet 67P/Churyumov-Gerasimenko, will occur in less than a month and we now have our best look yet at the area now green-lighted for touchdown. The picture above, made from two images acquired by Rosetta’s OSIRIS imaging instrument, shows a 500-meter circle centered on “Site J,” a spot on the comet’s “head” carefully chosen by mission scientists as the best place in which Philae should land, explore, and ultimately travel around the Sun for the rest of its days. And as of today, it’s a GO!

Site J was selected from among five other possible sites and was chosen because of the relative safety of its surface, its accessibility to consistent solar illumination, and the scientific and observational data it can make available to Philae’s suite of onboard instruments.

“None of the candidate landing sites met all of the operational criteria at the 100% level, but Site J is clearly the best solution,” said Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center.

Illustration of the Rosetta Missions Philae lander on final approach to a comet surface. The date is now set for landing, November 12. (Photo: ESA)

The mosaic above comprises two images taken by Rosetta’s OSIRIS (Optical, Spectroscopic, and Infrared Remote Imaging System) narrow-angle camera on Sept. 14 from a distance of about 30 km (18.6 miles). Image scale is 0.5 m/pixel.

As Comet 67P/CG continues toward perihelion its outgassing and sublimation jetting will undoubtedly increase, and Philae will be getting a front-row seat to the action.

“Site J is just 500-600 meters away from some pits and an area of comet outgassing activity,” said Holger Sierks, principal investigator for Rosetta’s OSIRIS camera from the Max Planck Institute for Solar System Research in Gottingen, Germany. “They will become more active as we get closer to the Sun.”

Watch “Landing on a Comet: the Trailer”

After completing a series of “Go/No-go” decisions by Rosetta’s flight dynamics team, Philae’s separation from Rosetta will occur on Nov. 12 at 08:35 GMT. It will land about seven hours later at around 15:30 GMT. Because of the distance to the comet and spacecraft — about 509 million km — confirmation of a successful touchdown won’t be received on Earth until 28 minutes and 20 seconds later. (And you thought Curiosity’s “seven minutes of terror” was nerve-wracking!)

Landing on a Comet: The Trailer

Artist's impression of the 100-kg Philae lander (screenshot) Credit: ESA/DLR

In less than a month, on November 12, 2014, the 100-kg Philae lander will separate from ESA’s Rosetta spacecraft and descend several kilometers down to the dark, dusty and frozen surface of Comet 67P/Churyumov-Gerasimenko, its three spindly legs and rocket-powered harpoon all that will keep it from crashing or bouncing hopelessly back out into space. It will be the culmination of a decade-long voyage across the inner Solar System, a testament to human ingenuity and inventiveness and a shining example of the incredible things we can achieve through collaboration. But first, Philae has to get there… it has to touch down safely and successfully become, as designed, the first human-made object to soft-land on the nucleus of a comet. How will the little spacecraft pull off such a daring maneuver around a tumbling chunk of icy rubble traveling over 18 km/s nearly 509 million km away? The German Aerospace Center (DLR) has released a “trailer” for the event, worthy of the best sci-fi film. Check it out below.

Want to see more? Of course you do. Keep an eye out for the 11-minute short film “Landing on a Comet – The Rosetta Mission” to be released soon on YouTube here, and follow the latest news from the Rosetta mission here (and here on Universe Today, too!)

“The reason we’re at this comet is for science, no other reason. We’re doing this to get the best science. To characterize this comet has never been done before.”

Original Material: DLR (CC-BY 3.0)
Footage: ESA
Credit 67P image: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Music: Omega by TimMcMorris

Source: DLR

September 8, 2014December 23, 2015 by Ken Kremer

Rosetta Captures Breathtaking Comet Views Advancing Landing Site Selection

Jagged cliffs and prominent boulders are visible in this image taken by OSIRIS on 5 September 2014 from a distance of 62 kilometres from comet 67P/Churyumov-Gerasimenko. The left part of the image shows a side view of the comet’s 'body', while the right is the back of its 'head'. One pixel corresponds to 1.1 metres. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

The Rosetta spacecraft is capturing ever more breathtaking views of its target comet that are significantly advancing landing site selection for the history making touchdown on the bizarre worlds nucleus by the attached Philae lander.

Today ESA released the latest high resolution images of Comet 67P/Churyumov-Gerasimenko taken by the OSIRIS science camera on Sept. 5, and is shown above.

Jagged cliffs and prominent boulders are clearly visible in unprecedented detail on the head and body of Comet 67P displaying a multitude of different terrains in the new image taken from a distance of 62 kilometers.

Meanwhile the Rosetta science team is using the OSIRIS and navcam camera images to create a preliminary map of the comets surface. The map is color coded to divide the comet into several distinct morphological regions.

Several morphologically different regions are indicated in this preliminary map, which is oriented with the comet’s ‘body’ in the foreground and the ‘head’ in the background. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA — Several morphologically different regions are indicated in this preliminary map, which is oriented with the comet’s ‘body’ in the foreground and the ‘head’ in the background.
Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA

“With various areas dominated by cliffs, depressions, craters, boulders or even parallel grooves, 67P/C-G displays a multitude of different terrains. Some areas even appear to have been shaped by the comet’s activity,” the Rosetta team said in the release.

The images were also shown at today’s scientific presentations at a special Rosetta research session at the 2014 European Planetary Science Congress being held in Cascais, Portugal.

The scientists are striving to meld all the imagery and data gathered from Rosetta’s 11 instruments in order to elucidate the composition and evolution of the different regions.

The mapping data is also being used to narrow the ‘Top 5’ Philae landing site candidates down to a primary and backup choice.

The final landing site selections will be made at a meeting being held this weekend on 13 and 14 September 2014 between the Rosetta Lander Team and the Rosetta orbiter team at CNES in Toulouse, France.

Four-image photo mosaic comprising images taken by Rosetta's navigation camera on 2 September 2014 from a distance of 56 km from comet 67P/Churyumov-Gerasimenko. The mosaic has been contrast enhanced to bring out details of the coma, especially of jets of dust emanating from the neck region. Credits: ESA/Rosetta/NAVCAM/Marco Di Lorenzo/Ken Kremer - kenkremer.com — Four-image photo mosaic comprising images taken by Rosetta’s navigation camera on 2 September 2014 from a distance of 56 km from comet 67P/Churyumov-Gerasimenko. The mosaic has been contrast enhanced to bring out details of the coma, especially of jets of dust emanating from the neck region.
Credits: ESA/Rosetta/NAVCAM/Marco Di Lorenzo/Ken Kremer – kenkremer.com

Philae’s history making landing on comet 67P is currently scheduled for around Nov. 11, 2014, and will be entirely automatic. The 100 kg lander is equipped with 10 science instruments.

The three-legged lander will fire two harpoons and use ice screws to anchor itself to the 4 kilometer (2.5 mile) wide comet’s surface. Philae will collect stereo and panoramic images and also drill 23 centimeters into and sample its incredibly varied surface.

Four-image photo mosaic comprising images taken by Rosetta's navigation camera on 31 August 2014 from a distance of 61 km from comet 67P/Churyumov-Gerasimenko. The mosaic has been rotated and contrast enhanced to bring out details. The comet nucleus is about 4 km across. Credits: ESA/Rosetta/NAVCAM/Ken Kremer/Marco Di Lorenzo — Four-image photo mosaic comprising images taken by Rosetta’s navigation camera on 31 August 2014 from a distance of 61 km from comet 67P/Churyumov-Gerasimenko. The mosaic has been rotated and contrast enhanced to bring out details. The comet nucleus is about 4 km across. Credits: ESA/Rosetta/NAVCAM/Ken Kremer/Marco Di Lorenzo

The comet nucleus is about 4 km (2.5 mi) across.

The team is in a race against time to select a suitable landing zone soon since the comet warms up and the surface becomes ever more active as it swings in closer to the sun and makes the landing ever more hazardous.

Stay tuned here for Ken’s continuing Rosetta, Earth and Planetary science and human spaceflight news.

Ken Kremer

Five candidate sites were identified on Comet 67P/Churyumov-Gerasimenko for Rosetta’s Philae lander. The approximate locations of the five regions are marked on these OSIRIS narrow-angle camera images taken on 16 August 2014 from a distance of about 100 km. Enlarged insets below highlight 5 landing zones. Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA Processing: Marco Di Lorenzo/Ken Kremer

September 5, 2014December 23, 2015 by Bob King

New Mosaic Reveals Jets Blasting from Rosetta’s Comet

Two jets of gas and dust blast from Comet 67P/C-G in this reassembled and enhanced mosaic made from four photos taken by Rosetta's navigation camera on September 2, Credit: ESA/Rosetta/ Navcam/Bob King

Hidden among the four new images of Comet 67P/Churyumov-Gerasimenko released by ESA this week are a pair of dusty jets shooting from the nucleus of Comet Churyumov-Gerasimenko. The photos were taken September 2, 2014 and posted as a mosaic of four separate images. I re-assembled the four, albeit imperfectly, and added some additional contrast to better show the dual geyser of ice crystals mixed with dust venting from the nucleus.

Four image montage of comet 67P/C-G, using images taken on 2 September. Credits: ESA/Rosetta/NAVCAM — Original four image montage of comet 67P/C-G, using images taken on September 2. The dark spot at center is imaging artifact. Credits: ESA/Rosetta/NAVCAM

An earlier Rosetta photo taken of Comet 67P/ Churyumov-Gerasimenko from a great distance and deliberately overexposed showed jets of dust-laden vapor shooting from the comet, but this is the first image I’m aware of that shows both the comet’s surface and its much fainter exhalations.

Jets or sprays of vaporizing ice are what gives a comet its lively appearance. Dust released with water vapor is ultimately pushed back by the pressure of sunlight to grow 67P/C-G’s dust tail. Ultraviolet light from the sun causes volatiles within the vapor to fluoresce a pale blue, creating a second ion or gas tail. The coma or comet atmosphere is a mix of both.

Rosetta took a long-exposure image with its wide-angle camera on August 2, 2014, to observe jets of dust escaping from the comet. The photo was taken from a distance of 550 kilometers. ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA — On August 2, 2014 at distance of 342 miles (550 km), Rosetta took this wide-angle view of the comet and jets of dust and vapor shooting into space.
ESA / Rosetta / MPS for OSIRIS Team MPS / UPD / LAM / IAA / SSO / INTA / UPM / DASP / IDA

We can expect the jets to grow stronger and hopefully more numerous as 67P/C-G approaches perihelion in August 2015. Because the spacecraft is maneuvering into orbit between the comet and sun, we don’t get the best view of jetting activity. The comet nucleus, illuminated by sunlight, drowns out the fainter jets. Rosetta will make an excursion to the nightside on September 24. Assuming the jets remain active, we might see them backlit by the sun as bright beams extending from the darkened nucleus into space.

September 1, 2014December 23, 2015 by Ken Kremer

Rosetta Now Up Close to Comet 67P – Snapping Mapping Mosaics for Momentous Philae Landing

Four-image photo mosaic comprising images taken by Rosetta’s navigation camera on 31 August 2014 from a distance of 61 km from comet 67P/Churyumov-Gerasimenko. The mosaic has been contrast enhanced to bring out details. The comet nucleus is about 4 km across.
Credits: ESA/Rosetta/NAVCAM/Ken Kremer – kenkremer.com/Marco Di Lorenzo
See rotated version and 4 individual images below[/caption]

ESA’s Rosetta orbiter has now moved in so close to its comet quarry that the primordial body overwhelms the screen, and thus its snapping mapping mosaics to capture the complete scene of the bizarre world so it can find the most suitable spot for the momentous Philae landing – upcoming in mid-November.

In fact Rosetta has ‘drawn and quartered’ the comet to collect high resolution views of Comet 67P/Churyumov-Gerasimenko with the navcam camera on Sunday, August 31.

The navcam quartet has just been posted to the Rosetta portal today, Monday, September 1, 2014. ESA invited readers to create global photo mosaics.

See above our four frame photo mosaic of navcam images Rosetta took on Aug. 31.

The purpose of taking the images as well as spectra and physical measurements up close is to find a ‘technically feasible’ Philae touchdown site that is both safe and scientifically interesting.

Below is the Rosetta teams four image navcam montage, arranged individually in a 2 x 2 raster.

Four-image montage comprising images taken by Rosetta's navigation camera on 31 August 2014 from a distance of 61 km from comet 67P/Churyumov-Gerasimenko. The comet nucleus is about 4 km across. Credits: ESA/Rosetta/NAVCAM — Four-image montage comprising images taken by Rosetta’s navigation camera on 31 August 2014 from a distance of 61 km from comet 67P/Churyumov-Gerasimenko. The comet nucleus is about 4 km across. Credits: ESA/Rosetta/NAVCAM

The navcam image raster sequence was taken from a distance of 61 km from comet 67P.

“Roughly one quarter of the comet is seen in the corner of each of the four images. The four images are taken over an approximately 20 minute period, meaning that there is some motion of the spacecraft and rotation of the comet between the images. As a result, making a clean mosaic out of the four images is not simple,” according to ESA’s Rosetta blog.

As I reported here last week, the ‘Top 5’ landing site candidates have been chosen for the Rosetta orbiters piggybacked Philae lander for humankind’s first attempt to land on a comet.

The potential touchdown sites were announced on Aug. 25, based on a thorough analysis of high resolution measurements collected by ESA’s Rosetta spacecraft over the prior weeks since it arrived at the pockmarked Comet 67P/Churyumov-Gerasimenko on Aug. 6, 2014.

See our montage of the ‘Top 5’ landing sites below.

Rosetta is a mission of many firsts, including history’s first ever attempt to orbit a comet for long term study.

Philae’s history making landing on comet 67P is currently scheduled for around Nov. 11, 2014, and will be entirely automatic. The 100 kg lander is equipped with 10 science instruments.

The new images released today are the best taken so far by the Navcam camera. The probes OSIRIS science camera are even more detailed, and will hopefully be released by ESA soon!

“This is the first time landing sites on a comet have been considered,” said Stephan Ulamec, Lander Manager at DLR (German Aerospace Center), in an ESA statement.

Since rendezvousing with the comet after a decade long chase of over 6.4 billion kilometers (4 Billion miles), a top priority task for the science and engineering team leading Rosetta has been “Finding a landing strip” for the Philae comet lander.

“The clock is ticking’ to select a suitable landing zone soon since the comet warms up and the surface becomes ever more active as it swings in closer to the sun and makes the landing ever more hazardous.

This image of comet 67P/Churyumov-Gerasimenko shows the diversity of surface structures on the comet's nucleus. It was taken by the Rosetta spacecraft's OSIRIS narrow-angle camera on August 7, 2014. At the time, the spacecraft was 65 miles (104 kilometers) away from the 2.5 mile (4 kilometer) wide nucleus. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/Enhanced processing Marco Di Lorenzo/Ken Kremer — This image of comet 67P/Churyumov-Gerasimenko shows the diversity of surface structures on the comet’s nucleus. It was taken by the Rosetta spacecraft’s OSIRIS narrow-angle camera on August 7, 2014. At the time, the spacecraft was 65 miles (104 kilometers) away from the 2.5 mile (4 kilometer) wide nucleus. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/Enhanced processing Marco Di Lorenzo/Ken Kremer

Stay tuned here for Ken’s continuing Rosetta, Earth and Planetary science and human spaceflight news.

Ken Kremer

ESA’s Rosetta spacecraft on final approach to Comet 67P/Churyumov-Gerasimenko in early August 2014. This collage of navcam imagery from Rosetta was taken on Aug. 1, 2, 3 and 4 from distances of 1026 km, 500 km, 300 km and 234 km. Not to scale. Credit: ESA/Rosetta/NAVCAM - Collage/Processing: Marco Di Lorenzo/Ken Kremer- kenkremer.com — ESA’s Rosetta spacecraft on final approach to Comet 67P/Churyumov-Gerasimenko in early August 2014. This collage of navcam imagery from Rosetta was taken on Aug. 1, 2, 3 and 4 from distances of 1026 km, 500 km, 300 km and 234 km. Not to scale. Credit: ESA/Rosetta/NAVCAM – Collage/Processing: Marco Di Lorenzo/Ken Kremer- kenkremer.com

Read my Rosetta series here:

5 Landing Site Candidates Selected for Rosetta’s Historic Philae Comet Lander

Rosetta Moving Closer to Comet 67P Hunting for Philae Landing Site

What’s Ahead for Rosetta – ‘Finding a Landing Strip’ on Bizarre Comet 67P/Churyumov-Gerasimenko

Rosetta Arrives at ‘Scientific Disneyland’ for Ambitious Study of Comet 67P/Churyumov-Gerasimenko after 10 Year Voyage

Rosetta on Final Approach to Historic Comet Rendezvous – Watch Live Here

Rosetta Probe Swoops Closer to Comet Destination than ISS is to Earth and Reveals Exquisite Views

Rosetta Orbiter less than 500 Kilometers from Comet 67P Following Penultimate Trajectory Burn

Rosetta Closing in on Comet 67P/Churyumov-Gerasimenko after Decade Long Chase

July 21, 2014December 23, 2015 by Jason Major

Once Upon a Time There Was a Spacecraft Called Rosetta…

The road to a comet isn't an easy one! Luckily Rosetta and Philae have a lot of help.

…and that time is now! ESA’s Rosetta spacecraft is just over a mere two weeks away from its arrival at Comet 67P/Churyumov-Gerasimenko (which has recently surprised everyone with its binary “rubber duckie” shape) and the excitement continues to grow — and rightfully so, since after ten years traveling through the Solar System Rosetta is finally going to achieve its goal of being the first spacecraft to orbit a comet!

As part of the “Are We There Yet” campaign to encourage public participation in this historic space exploration event, ESA has released the next installment of Rosetta’s story in adorable animated format. Check it out above, and feel free to fall in love with a solar-powered spacecraft.

Keep up with Rosetta’s journey on the ESA website here, and enter the #RosettaAreWeThereYet contest by sharing your photos here (you could win a trip to ESA’s Operations Center in Darmstadt, Germany in November for Philae’s landing party!)

Video: ESA