ESA Rosetta: Fissure spanning 100 metres discovered on Comet 67/P

A fissure spanning over 100 meters across the neck of Rosetta’s comet 67P raises the question of if, or when, the comet will break up. 

The fissure is part of released studies by Rosetta scientists in the journal Science. 

Credit: ESA/Rosetta, Illustration, T.Reyes

Not all comets break up as they vent and age, but for ESA 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.

The fissure is part of the analysis in a new set of science papers published this week.

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.

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

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.'

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.

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

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.

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.

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.

Read the full article here

ESA Rosetta Comet 67/P Mission: Rosetta Team Uncovers More Secrets

A colour image of Comet 67P/Churyumov-Gerasimenko composed of three images taken by Rosetta’s scientific imaging system OSIRIS in the red, green and blue filters; the images were taken on August 6, 2014 from a distance of 120 km from the comet. 

Image credit: ESA / Rosetta / MPS / OSIRIS Team / UPD /LAM / IAA / SSO / INTA / UPM / DASP / IDA.

The familiar shape of the comet has now had many of its vital statistics measured: the small lobe measures 2.6 × 2.3 × 1.8 km and the large lobe 4.1 × 3.3 × 1.8 km.

The total volume of the comet is 21.4 km3. Rosetta’s Radio Science Instrument has measured its mass to be 10 billion tons, yielding a density of 470 kg/m3.

By assuming an overall composition dominated by water ice and dust with a density of 1,500–2,000 kg/m3, Rosetta scientists show that the comet has a very high porosity of 70–80 percent, with the interior structure likely comprising weakly bonded ice-dust clumps with small void spaces between them.

The OSIRIS instrument has imaged some 70 percent of the surface to date: the remaining unseen area lies in the southern hemisphere that has not yet been fully illuminated since Rosetta’s arrival.

The scientists have so far identified 19 regions separated by distinct boundaries and, following the ancient Egyptian theme of the Rosetta mission, these regions are named for Egyptian deities, and are grouped according to the type of terrain dominant within.

The 19 regions identified on 67P/Churyumov–Gerasimenko are separated by distinct geomorphological boundaries; they are grouped according to the type of terrain dominant within each region. 

Five basic categories of terrain type have been determined: dust-covered (Ma’at, Ash and Babi); brittle materials with pits and circular structures (Seth); large-scale depressions (Hatmehit, Nut and Aten); smooth terrains (Hapi, Imhotep and Anubis), and exposed, more consolidated surfaces (Maftet, Bastet, Serqet, Hathor, Anuket, Khepry, Aker, Atum and Apis). 

Image credit: ESA / Rosetta / MPS / OSIRIS Team / UPD /LAM / IAA / SSO / INTA / UPM / DASP / IDA.

Five basic, but diverse, categories of terrain type have been determined: dust-covered; brittle materials with pits and circular structures; large-scale depressions; smooth terrains; and exposed more consolidated surfaces.

Much of the northern hemisphere is covered in dust. As the comet is heated, ice turns directly into gas that escapes to form the atmosphere or coma.

Dust is dragged along with the gas at slower speeds, and particles that are not traveling fast enough to overcome the weak gravity fall back to the surface instead.

Some sources of discrete jets of activity have also been identified. While a significant proportion of activity emanates from the smooth neck region, jets have also been spotted rising from pits.

The gases that escape from the surface have also been seen to play an important role in transporting dust across the surface, producing dune-like ripples, and boulders with ‘wind-tails,’ the boulders act as natural obstacles to the direction of the gas flow, creating streaks of material ‘downwind’ of them.

“Because comets have very little gravity, dust and gas flow freely into space. But we were surprised to find a cloud of particles orbiting the comet that are large and heavy enough to defy the Sun’s radiation pressure,” said Dr Dennis Bodewits of the University of Maryland.

The scientists were able to make this discovery thanks to OSIRIS’ very sensitive cameras.

“Each pixel is about 30 cm. You couldn’t see a coffee cup, but you could see a large lunchbox. The resolution is about 10 times higher than Google Earth.”

According to the team, 67P/Churyumov-Gerasimenko was releasing the earthly equivalent of 1.2 liters of water into space every second at the end of August 2014.

MIRO (Microwave Instrument for the Rosetta Orbiter)

Credit: ESA

“In observations, made by the Microwave Instrument for Rosetta Orbiter (MIRO), over a period of three months, the amount of water in vapor form that the comet was dumping into space grew about tenfold,” said Dr Sam Gulkis of NASA’s Jet Propulsion Laboratory in Pasadena.

“To be up close and personal with a comet for an extended period of time has provided us with an unprecedented opportunity to see how comets transform from cold, icy bodies to active objects spewing out gas and dust as they get closer to the Sun.”

ESA Rosetta: Comet 67/P surrounded by dusty vapour cloud

ESA Rosetta NAVCAM Close-up of Comet 67P on January 3, 2015, showing the larger of the two lobes (boulder Cheops labelled), multiple jets of dust, and what are most likely dust particles or aggregates in the comet’s coma or atmosphere. 

Credit: ESA/Rosetta/NAVCAM

Comets fly around the Sun surrounded by a cloud of vapour and grime that's as old as the Solar System itself.

You've probably noticed little flecks and streaks in photos returned by the Rosetta spacecraft in the blackness of space surrounding comet 67P/Churyumov-Gerasimenko.

After a recent year-end break, the ESA Rosetta team has returned with new updates on the comet including a series of four images recently released as a mosaic.

The pictures were processed to highlight surface features; the space around the nucleus is black in comparison. But if we take a closer look at what first appears void, we soon discover it's not empty at all.

Add caption

In photos taken January 3rd, the writer of ESA's Rosetta blog notes that "some of the streaks and specks seen around the nucleus will likely be dust grains ejected from the comet, captured in the 4.3 second exposure time."

Using an image-editing tool like Photoshop, we can hold back the glare of the nucleus and "open up" the shadows around the comet.

Jets of dust released by vaporizing ice are the most obvious features to emerge.

The soft, low-contrast plumes plow into the vacuum around the nucleus wrapping it in a silky cocoon of gas and dust, a tenuous atmosphere that reflects sunlight far more weakly than the comet itself.

While staring at dust spots may not produce the same magical feelings as watching a sunrise, it's fascinating nonetheless to contemplate what we're seeing.

If you've been struck by the beauty of a comet's meteor-like head trailing a wispy tail, you're looking at what countless individual grains of dust can do when sculpted by the master hand of the Sun.

Perusing images of 67P, we see the process in its infancy as individual grains and small clots are released into space to be fashioned into something grander.

Dust and gases released by the comet reflect so little light compared to the nucleus they require special processing to see clearly. 

In this photo, many of the small, irregular specks may be cometary dust grains captured in the 4.3 second exposure. 

Credit: ESA/Rosetta/NAVCAM

Rosetta's Micro-Imaging Dust Analysis System or MIDAS measures the rate at which dust sweeps past the spacecraft and its size distribution.

MIDAS catches dust grains by exposing a sticky target surface into space and waiting for a mote to drift by.

It snatched its first one last November, a larger than expected mote measuring about 1/100 of a millimeter across with a complex shape and fluffy texture.

Analysis of the composition of another dust grain named "Boris" made by the COSIMA instrument has identified sodium and magnesium.

Magnesium is no surprise as 95% of known minerals observed in comets resemble olivine and pyroxenes, common in meteorites and in the upper mantle of the Earth.

Sodium has also been seen before in comas and tails, and originates in dust grains, but its mineral source remains uncertain.

As we might study the makeup of the dust Pig-Pen leaves in his wake to identify traces of earthly dirt, micro-organisms, pollen, pollution, and even recent volcanic eruptions, so we examine each mote that sprays Rosetta's way, looking for clues to the origin of the planets and Solar System.

At right is a streak that could either be a larger, fast-moving dust particle that trailed during the exposure or perhaps a cosmic ray hit. 

Credit: ESA/Rosetta/NAVCAM

The mosaic image of the comet taken on January 3rd and processed, like most of ESA’s comet images, to highlight surface features. 

Credit: ESA/Rosetta/NAVCAM

Image of the first dust grain (center) captured by MIDAS. The bar at top left is 0.01 mm wide. 

Credit: Courtesy Mark Bentley

COSIMA’s first dust grains. Left: an image of the target plate (measuring 1 cm by 1 cm) on which the grains were collected; right: a section of the plate showing it on August 17th (top) when no dust grains were visible and 24 August 24th (bottom) when two large dust grains were detected. 

The plate is illuminated from the right by LEDs, and the length of the shadows is proportional to the height of the dust grains. 

Credit: ESA /Rosetta /MPS for COSIMA Team MPS /CSNSM /UNIBW /TUORLA /IWF /IAS /ESA / BUW /MPE /LPC2E /LCM /FMI /UTU /LISA /UOFC /vH&S

ESA Rosetta: Latest Four-image mosaic of Comet 67/P

This four-image mosaic from ESA Rosetta spacecraft comprises images taken from a distance of 28.4 km from the centre of Comet 67P/Churyumov-Gerasimenko on 3 January. 

The image resolution is  2.4 m/pixel and the mosaic measures 4.4 x 4.2 km. 

Credit: ESA

This four-image mosaic from ESA Rosetta spacecraft comprises images taken from a distance of 28.4 km from the centre of Comet 67P/Churyumov-Gerasimenko on 3 January.

The image resolution at this distance is 2.4 m/pixel and the individual 1024 x 1024 frames measure 2.5 km across.

The mosaic is slightly cropped and rotated and measures about 4.4 x 4.2 km.

Because rotation and translation of the comet during the imaging sequence make it difficult to create an accurate mosaic, always refer to the individual images before drawing conclusions about any strange structures or low intensity extended emission.

The mosaic shows a great view across the Imhotep region, which includes the Cheops boulder on the larger of the two comet lobes.

The name of this region was revealed during the AGU conference in December (see the 17 Dec post).

The smaller of the comet’s lobes is situated to the far left of the mosaic.

The illumination conditions contribute to the interesting view of the features standing out against the shadowed foreground, close to the centre.

Some of the streaks and specks seen around the nucleus will likely be dust grains ejected from the comet, captured in the 4.3 second exposure time.

ESA Rosetta: First colour image of Comet 67/P

Scientists superimposed images taken with three different filters.

Credit: ESA

The first colour image from the ESA Rosetta spacecraft shows that Comet 67P is even more dark and monochrome than expected.

Despite being carefully assembled from three images taken with red, green and blue filters, the shot still looks effectively black-and-white.

It comes from the Osiris camera, which is on board the orbiting craft that last month made history by dropping a lander onto the comet's surface.

The Osiris team says 67P is "as black as coal" and surprisingly uniform.

The image was released by the Max Planck Institute for Solar System Research, which leads the consortium behind the camera.

"We like to refer to Osiris as the eyes of Rosetta," said the instrument's principal investigator Dr Holger Sierks.

But the camera is unlike human eyes, and so the colour image had to be produced by combining three separate shots.

This was no easy task. Rosetta is constantly moving and the comet beneath is spinning, so various changes in angle had to be accounted for.

The result is an image that looks remarkably similar to previous, greyscale views of 67P.

"As it turns out, 67P looks dark grey, in reality almost as black as coal," Dr Sierks said.

By the time the image is brightened enough for us to see the comet's features, it looks much lighter grey - but not what anyone would call colourful.

Using observations from the ground, scientists had already observed that Comet 67P, like many other small bodies in our Solar System, appeared to be grey "on average".

But the new results reveal that it seems to be this dark, coal colour all over - with little variation.

That suggests that its surface composition is fairly uniform and shows no sign of ice patches, which would appear bluish.

The comet's ice is presumably hidden below its dusty, boulder-strewn surface.

ESA Rosetta: First measurements of Comet 67/P’s water ratio

ESA Rosetta’s measurement of the deuterium-to-hydrogen ratio (D/H) measured in the water vapour around Comet 67P/Churyumov–Gerasimenko. 

The measurements were made using ROSINA’s DFMS double focusing mass spectrometer between 8 August and 5 September 2014.

Credit: ESA, DLR.

Deuterium is an isotope of hydrogen with an added neutron.

The ratio of deuterium to hydrogen in water is a key diagnostic to determining where in the Solar System an object originated and in what proportion asteroids and/or comets contributed to Earth’s oceans.

The graph displays the different values of D/H in water observed in various bodies in the Solar System.

The data points are grouped by colour as planets and moons (blue), chondritic meteorites from the Asteroid Belt (grey), comets originating from the Oort cloud (purple) and Jupiter family comets (pink). Rosetta’s Jupiter-family comet is highlighted in yellow.

Diamonds represent data obtained in situ; circles represent data obtained by astronomical methods.

The lower part of the graph shows the value of D/H measured in molecular hydrogen in the atmosphere of the giant planets of the Solar System (Jupiter, Saturn, Uranus, Neptune) and an estimate of the typical value in molecular hydrogen for the protosolar nebula, from which all objects in our Solar System formed.

The ratio for Earth’s oceans is 1.56 ×10–4 (shown as the blue horizontal line in the upper part of the graph).

The value for Comet 67P/Churyumov–Gerasimenko is found to be 5.3 x 10–4, more than three times greater than for Earth’s oceans.

The discovery fuels the debate on the origin of Earth’s oceans and whether asteroids or comets played the bigger role in delivering water.

ESA Rosetta: Earth's Water Came from Asteroids, Not Comets

ESA Rosetta’s navigation camera obtained the four images in this mosaic on Dec. 7, 2014, from a distance of 12.2 miles (19.7 km) from the center of Comet 67P/Churyumov-Gerasimenko.

Credit: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0

Asteroids, not comets, may have delivered most of Earth's water to the planet when the solar system was young, new data from the ESA Rosetta probe orbiting comet 67/P suggests.

Comets are some of the solar system's most primitive building blocks, with many dating to soon after its formation.

Scientists think that these dirty snowballs probably helped seed Earth with key ingredients for life, such as organic compounds.

The European Space Agency's (ESA) Rosetta spacecraft is helping scientists learn more about the role these icy nomads have played in the evolution of the solar system and life on Earth by analyzing the composition of Comet 67P/Churyumov–Gerasimenko.

In August, Rosetta became the first spacecraft to orbit a comet, and in November, its Philae lander became the first probe to make a soft touchdown on a comet's surface.

Rosetta is also the first mission to escort a comet as it travels around the sun.

Now, Rosetta has helped solve a mystery about how Earth became the watery world it is today.

Before Rosetta began orbiting Comet 67P/C-G in August, it was using an instrument known as ROSINA (short for Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) to analyze the chemical fingerprint of gases in the comet's fuzzy envelope.

Scientists focused on data from the instrument regarding water to help uncover whether asteroids or comets delivered the water in Earth's oceans.

Rosetta has provided data from Comet 67P/C-G, another Kuiper Belt comet.

However, Rosetta has discovered that this comet possesses an even higher deuterium-to-hydrogen ratio than seen in Oort Cloud comets, three times the amount of heavy water compared to normal water as Earth has.

If Earth's water had come from Kuiper Belt objects, even if most of them were like comet 103P/Hartley 2, and if only a small fraction were like Comet 67P/C-G, Earth's deuterium-to-hydrogen ratio would be significantly higher than it is today.

"This probably rules out Kuiper Belt comets from bringing water to Earth," Altwegg said. Instead, most of Earth's water was probably delivered by asteroids, Altwegg said.

"Today's asteroids have very little water, that's clear," Altwegg added. "But that was probably not always the case. During the Late Heavy Bombardment 3.8 billion years ago, at that time, asteroids could have had much more water than they could now."

The asteroids seen now "have stayed in the vicinity of the sun for 4.6 billion years," Altwegg said.

"They've lost water due to the sun, due to heat. But to start with, they might have had much more water than they have now."

Future analysis of ice-rich bodies in the asteroid belt could shed light on whether Earth's water really did come from there, Altwegg said.

ESA Rosetta mission: After the comet landing comes the real Science

Artist’s impression of ESA’s Rosetta cometary probe. 

The spacecraft is covered with dark thermal insulation in order to keep it warm while venturing into the coldness of the outer Solar System, beyond Mars orbit. 

Credit: ESA

With the Philae lander’s mission complete, ESA's Rosetta probe will now continue its own extraordinary exploration, orbiting Comet 67P/Churymov–Gerasimenko during the coming year as the enigmatic body arcs ever closer to our Sun.

Last week, ESA's Rosetta spacecraft delivered its Philae lander to the surface of the comet for a dramatic touchdown.

The lander’s planned mission ended after about 64 hours when its batteries ran out, but not before it delivered a full set of results that are now being analysed by scientists across Europe.

Rosetta’s own mission is far from over and the spacecraft remains in excellent condition, with all of its systems and instruments performing as expected.

“With lander delivery complete, Rosetta will resume routine science observations and we will transition to the ‘comet escort phase',” says Flight Director Andrea Accomazzo.

“This science-gathering phase will take us into next year as we go with the comet towards the Sun, passing perihelion, or closest approach, on 13 August, at 186 million kilometres from our star.”

ESA Rosetta mission: Philae lander - the sound of a Comet Touchdown

Image credit: ESA/ATG medialab – Audio file credit: ESA /Rosetta /Philae /SESAME /DLR

Sensors in the feet of Rosetta’s lander Philae have recorded the sound of touchdown as it first came into contact with Comet 67P/Churyumov-Gerasimenko. 

The instrument, SESAME-CASSE, was turned on during the descent and clearly registered the first touchdown as Philae came into contact with the comet, in the form of vibrations detected in the soles of the lander’s feet.

Focus on SESAME. Sensors are located in the three feet as well as in the units of the APXS (centre) and MUPUS-Pen (to the upper right of centre) instruments. Credits: ESA/ATG medialab

SESAME is the lander’s Surface Electrical Sounding and Acoustic Monitoring Experiment, and comprises three suites of instruments:

• CASSE – the Comet Acoustic Surface Sounding Experiment, which allows mechanical parameters of the surface to be deduced, along with details of the structure of the subsurface;
• DIM – the Dust Impact Monitor, which measures properties of impacting comet grains;
• PP – the Permittivity Probe, which determines one of the key electrical properties of the material beneath Philae, which is linked to the water ice content of the surface.

Klaus Seidensticker from the DLR Institute of Planetary Research says: “Our data record the first touchdown and show that Philae’s feet first penetrated a soft surface layer – possibly a dust layer – several centimetres thick until they hit a hard surface – probably a sintered ice-dust layer – a few milliseconds later.”

ESA Rosetta Philae completes science mission before shutdown

Philae's first touchdown seen by Rosetta's NavCam

Rosetta’s lander has completed its primary science mission after nearly 57 hours on Comet 67P/Churyumov–Gerasimenko.

After being out of communication visibility with the lander since 09:58 GMT / 10:58 CET on Friday, Rosetta regained contact with Philae at 22:19 GMT /23:19 CET last night.

The signal was initially intermittent, but quickly stabilised and remained very good until 00:36 GMT / 01:36 CET this morning.

In that time, the lander returned all of its housekeeping data, as well as science data from the targeted instruments, including ROLIS, COSAC, Ptolemy, SD2 and CONSERT.

This completed the measurements planned for the final block of experiments on the surface.

ESA Rosetta team broadcast new pictures from Philae lander

Prof Jean Pierre Bibring (CNES) ESA Rosetta science team leader at the ESA update broadcast revealing new pictures from Philae lander sitting on the Comet 67/P.

The Philae is sitting close to a rocky cliff like structure, with 2 legs out of three on firm surface. The surface appears to be rocky not powdery.

The instruments on Philae are firing up to gather as much science data as possible while the onboard matteries are running.

Given that the Philae may be sitting on partial shade there is some doubt as to whether the solar panels can be deployed to extend the power cycle of the instruments' data gathering.

Prof Ulamec (DLR) of the ESA Rosetta team shows the approx area (the blue diamond) that the team believe Philae is located, on the comet.

There is some concern that is in the shade of a cliff-like structure.

The ESA team are under great pressure to produce pictures and data from the comet and this is clearly showing up in the professional but sleep deprived presentations.

Short animated sequence showing Philae leaving Rosetta on its descent to Comet 67/P.

This image from Rosetta shows a tiny dot that is the Philae lander in transit to comet 67/P. 

This is a composite picture made up of the others (above) showing an almost panaramic view around Philae.

ESA Rosetta Philae Lander may have bounced on landing

Philae may have landed not once but twice, that’s the final message from Esa this evening.

According to Stephan Ulamec, Philae Lander Manager, DLR, the lander team believe that Philae may have bounced from the surface and settled again in a slightly different place.

Engineers know that the anchoring harpoons did not fire. It is also known that the communications link to Rosetta failed intermittently in an irregular pattern shortly after the landing but always immediately re-established itself.

However, science data has been received and is currently being processed, but the promised first panorama from the surface has not been released.

Rosetta is now out of touch with Philae as the orbiter has dipped below the horizon of the comet. The link to Philae was lost a little earlier than expected but this is probably because a hill or boulder was in the way of the line of sight.

Right now, Philae should be working through its first automatic sequence of science experiments. Contact will be re-established through Rosetta later tonight, and the data downlinked.

There will also be more telemetry to assist the engineers in understanding the exact sequence of events during the landing.

We will know more tomorrow.

ESA Rosetta: Landing Site on Comet 67/P named "Agilkia"

This image taken by ESA's Rosetta robe, shows the Philae lander's possible future landing site, called "Agilkia," on Comet 67P/Churyumov-Gerasimenko. 

Image taken on Oct. 30, 2014. 

Credit: ESA /Rosetta /NAVCAM

A probe chasing a comet is about to make a daring attempt to land on its deep-space target, and now, the robot's landing site officially has a name.

The Rosetta mission's Philae lander is expected to make its home on Comet 67P/Churyumov-Gerasimenko at a site now called "Agilkia," European Space Agency officials announced today (Nov. 4).

The new name was chosen from 8,000 entries after space agency officials issued a request to the public for suggestions.

The name Agilkia was suggested by more than 150 people as part of the competition. (Until today, the landing site was unofficially called "Site J.")

The new name comes from an island on the Nile River in Egypt. The name fits with the other monikers given to different parts of the comet-chasing mission.

The Philae lander is named for an obelisk discovered on Philae Island in the Nile, while Rosetta, the spacecraft that has carried Philae into deep space, is named after the Rosetta Stone, an ancient Egyptian tablet that helped modern archaeologists translate hieroglyphics.

Some of the artifacts found on Philae Island were actually relocated to Agilkia Island to protect them.

"The decision was very tough," the DLR German Aerospace Center's Felix Huber, chairman of the Philae Lander Steering Committee, said in a statement.

"We received so many good suggestions on how to name Site J, and we were delighted with such an enthusiastic response from all over the world. We wish to thank all participants for sharing their great ideas with us."

The goal of the $1.6 billion (1.3 billion euros) Rosetta mission is to learn more about the science of comets.

Scientists are also interested in researching what comets might reveal about the way life evolved in the solar system.

Officials chose the landing site because it has some smooth terrain, and could be the safest area to set down the probe.

While many people suggested Agilkia as the landing site name, ESA officials chose Alexandre Brouste of France as the winner of the competition.

Brouste will get to watch the live landing event, expected to take place on Nov. 12, from ESA's Space Operations Control Centre in Darmstadt, Germany.

"In eight days' time, Philae will be deployed from the orbiter onto Agilkia," Fred Jansen, ESA Rosetta mission manager, said in the same statement.

"On 12 November, we'll be attempting a unique comet landing, an even more ambitious endeavor to unlock secrets of our most remote origins." 

ESA Rosetta Team release composite picture of Comet 67/P

Four-image mosaic of Comet 67P/C-G on 30 October. 

Credits: ESA /Rosetta /NAVCAM

The mosaic comprises four individual NAVCAM images taken on 30 October when the Rosetta spacecraft was 26.8 km from the centre of the comet.

The image resolution at this distance is 2.27 m/pixel, and thus each 1024 x 1024 frame covers 2.3 km at the comet. The slightly cropped mosaic covers 4.0 x 3.7 km.

Even at this increased distance from the nucleus, the time between the four NAVCAM images means that it is difficult to make a completely accurate mosaic.

Thus, as always, caution is needed in interpreting some features on the surface and faint emission around the nucleus.

The four individual images that make up this mosaic are provided here.

The centre of the landing site is located roughly in the top centre, close to the horizon in this viewing angle; check against this image to help with orientation.

The large depression that characterises the smaller lobe of the comet can be seen in the right-hand side at top right, while parts of the larger lobe can be seen in the lower half, with the still unseen portion of the comet again cast in dramatic shadow.

Vintage Comet 67P/Churyumov–Gerasimenko

It was 45 years ago when astronomer Klim Churyumov and Svetlana Gerasimenko, one of his researchers, unwittingly began a new chapter in the history of space exploration.

During a comet-hunting expedition to Alma-Ata Observatory, Kazakhstan, they discovered the bizarre, ice-rich object, subsequently named Comet 67P/Churyumov–Gerasimenko, that is now under close scrutiny by ESA’s Rosetta spacecraft.

In November 2014 it is hoped that more secrets will be revealed when Rosetta’s Philae attempts the first soft-landing on the nucleus of a comet.

These two images, taken with a wide-angle Schmidt telescope, were exposed a short time apart during the historic expedition.

The pair of photographic plates, taken by Klim Churyumov on 21 September 1969, shows a fuzzy object (indicated by the arrows) shifting position slightly in the night sky.

The comet appears indistinct because its solid heart is surrounded by a coma of gas and dust, material that was ejected into space as the ice-rich nucleus was warmed by solar radiation.

Before the era of digital cameras, imaging astronomical objects was a slow, painstaking process involving lengthy exposures of the same part of the sky on glass plates that were coated with a light-sensitive emulsion.

Glass-backed plates, rather than film, were commonly used in astronomy because they did not shrink or deform noticeably in the development process or under different environmental conditions.

They were held in large-format frames for wide-field imaging.

Each successive plate was exposed after an interval of 20–30 minutes.

The plates then had to be taken back to the laboratory to be processed and studied.

By comparing the images, it was possible to find new comets and other fast-moving objects as they shifted across the background of more distant, ‘fixed’ stars.

Since the discovery of this comet, advances in space exploration have revolutionised comet studies, starting with the first close-up images of comet Halley obtained by ESA’s Giotto spacecraft in 1986.

Since then, a handful of comets has been visited by spacecraft and some comet dust has been brought back to Earth.

These studies show that comets can no longer be regarded simply as dirty snowballs. Ideas about their origins and nature have greatly altered and there are still many questions, which Rosetta and its Philae lander could go a long way towards answering.

ESA Rosetta’s Comet Landing Site J Close Up

An annotated mosaic from the Rosetta spacecraft shows “Site J,” the primary landing site on comet 67P/Churyumov–Gerasimenko for the mission’s Philae lander.

Image Credit: ESA /Rosetta /MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

A mosaic from the European Space Agency’s Rosetta spacecraft shows “Site J,” the primary landing site on comet 67P/Churyumov–Gerasimenko for the mission’s Philae lander. Rosetta is the first mission to attempt a soft landing on a comet.

The mosaic comprises two images taken by Rosetta’s OSIRIS narrow-angle camera on Sept. 14, 2014, from a distance of about 19 miles (30 kilometers).

The image scale is 1.6 feet (0.5 meters) per pixel. The red ellipse is centered on the landing site and is approximately 1,600 feet (500 meters) in diameter.

Site J is located on the smaller of the comet’s two lobes. On Nov. 12, the Rosetta spacecraft will release Philae at 01:03 a.m. PST/10:03 CET/09:03 UTC (the time the signal is received on Earth). Touchdown of Philae on Site J is expected about seven hours later, at around 8 a.m. PST/17:00 CET/16:00 UTC (Earth Received Time).

Launched in March 2004, Rosetta was reactivated in January 2014 after a record 957 days in hibernation.

Composed of an orbiter and lander, Rosetta's objectives since arriving at comet 67P/Churyumov-Gerasimenko earlier this month have been to study the celestial object up close in unprecedented detail, prepare for landing a probe on the comet's nucleus in November, and following the landing, track the comet's changes as it sweeps past the sun.

Comets are time capsules containing primitive material left over from the epoch when the sun and its planets formed.

Rosetta's lander will obtain the first images taken from a comet's surface and will provide comprehensive analysis of the comet's possible primordial composition by drilling into the surface.

Rosetta also will be the first spacecraft to witness at close proximity how a comet changes as it is subjected to the increasing intensity of the sun's radiation.

Observations will help scientists learn more about the origin and evolution of our solar system and the role comets may have played in seeding Earth with water, and perhaps even life.

ESA Rosetta's lander, Philae snaps image of comet 67P/Churyumov-Gerasimenko

A camera aboard Rosetta's lander, Philae, snapped this image of comet 67P/Churyumov-Gerasimenko on Oct. 7.

Credit: ESA /Rosetta /Philae /CIVA

With an icy comet lurking just over its shoulder, a far-flung European spacecraft snapped a selfie in outer space.

The photographer was Philae, a small lander attached to the European Space Agency's (ESA) Rosetta probe.

At the time (Oct. 7), Philae was just 10 miles (16 kilometers) away from the Comet 67P/Churyumov-Gerasimenko, but they're about to get much closer.

On Nov. 12, Philae is scheduled to separate from Rosetta to make an unprecedented touchdown on the comet.

After a decade-long, 4-billion-mile (6 billion km) journey from Earth, Rosetta was awakened from a deep sleep in January.

Then, through a series of carefully choreographed maneuvers, the probe arrived at 67P/Churyumov-Gerasimenko in August and became the first spacecraft to ever orbit a comet.

The new image, released by ESA this week, shows off Rosetta's glinting 52-foot-long (16-meter) solar arrays.

The composition is almost identical to a selfie Philae snapped last month, but at 31 miles (50 kilometers) away, the comet looked much smaller in that photo.

ESA Rosetta - Lutetia's Lineaments: Dark side of asteroid hosts hidden crater

ESA's Rosetta spacecraft data. Tracing Lutetia’s grooves.

Credit: ESA /Rosetta /MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

Grooves found on Lutetia, an asteroid encountered by ESA's Rosetta spacecraft, point to the existence of a large impact crater on the unseen side of the rocky world.

ESA's Rosetta spacecraft flew past Lutetia at a distance of 3168 km in July 2010, en route to its 2014 rendezvous with its target comet.

The spacecraft took images of the 100 km-wide asteroid for about two hours during the flyby, revealing numerous impact craters and hundreds of grooves all over the surface.

Impact craters are commonly seen on all Solar System worlds with solid surfaces, recording an intense history of collisions between bodies. However, grooves are much less prevalent.

To date, they have been discovered by visiting spacecraft only on the Martian moon Phobos and the asteroids Eros and Vesta.

The way in which grooves are formed on these bodies is still widely debated, but it likely involves impacts.

Shock waves from the impact travel through the interior of a small, porous body and fracture the surface to form the grooves.

"For Lutetia, by assuming that the grooves were formed in concentric patterns around their source impact crater, we identified 200 such features falling into distinct 'families', correlated with three different impact craters," describes Sebastien Besse, a research fellow at ESA's Technical Centre, ESTEC, in the Netherlands, and lead author of the paper published in Planetary and Space Science this month.

One of the groove systems on Lutetia is associated with the Massilia crater and another with the North Pole Crater Cluster, which comprises a number of superimposed craters. Both are on the asteroid's northern hemisphere.

This anaglyph 3D image of Lutetia can be viewed using stereoscopic glasses with red–green or red–blue filters. 

The two images making up this image were taken several minutes before Rosetta’s closest approach to the asteroid on 10 July 2010. 

The left-eye view was captured at 15:41:39 GMT from a distance of 4274 km from Lutetia’s surface and the right-eye view at 15:41:03 GMT from 4038 km (closest approach was at 15:45 GMT). 

Credit: ESA/H. Sierks (MPS, Göttingen, Germany)

But another group of grooves points to a crater not seen during Rosetta's brief flyby, in the asteroid's southern hemisphere.

Its implied presence has earned it the nickname 'Suspicio'. The grooves related to Suspicio cover a large area on the asteroid, suggesting it may span several tens of kilometres .

By comparison, Massilia, the largest known crater on Lutetia, is about 55 km wide, and the largest of the polar cluster is about 34 km across.

"These three major impacts seriously deformed Lutetia's surface," adds Sebastien.

Looking face on at the North Pole Crater Cluster (purple outline) on asteroid Lutetia, with Massilia crater to the lower left (red outline). 

Marked on the image are the concentric grooves or ‘lineaments’ associated with the large craters. 

The lineaments coloured blue infer the presence of a large crater, nicknamed Suspicio, on the unseen portion of Lutetia. 

Yellow denotes lineaments not associated with any of the craters discussed in this study. 

Credit: ESA /Rosetta /MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

"As with grooves seen on other asteroids that may also be associated with impact events, this study provides new insights into the catastrophic history of these small bodies."

By observing how subsequent small craters lie over the grooves on Lutetia, the scientists determined the relative ages of the three larger cratering events.

Massilia is thought be the oldest of the three craters and the polar cluster the youngest, with Suspicio between.

The authors also looked at other, independent measurements of Lutetia, including ground-based observations with the Infrared Telescope Facility and space-based observations with ESA's Herschel and NASA's Spitzer.

The infra-red location of Suspicio crater on the unseen southern hemisphere of asteroid Lutetia (marked in blue). 

The hidden crater could be up to 45 km in diameter, the blue outlines correspond to diameter estimates of 15, 30 and 45 km, respectively. 

The crater is inferred based on the numerous grooves or ‘lineaments’ seen concentric to the crater in the northern hemisphere of the asteroid. 

There are no image data available for this side of the asteroid, as can be inferred from the blank shape model. 

Credit: ESA /Rosetta /MPS for OSIRIS Team MPS /UPD /LAM /IAA /SSO /INTA /UPM /DASP /IDA

The Infrared Telescope Facility suggested different compositions between the northern and southern hemisphere of the asteroid.

Sebastien and his colleagues propose that a large impact, presumably the one forming Suspicio, excavated enough material of a different composition to account for the observed differences.

"Our study ties together several independent analyses of Lutetia into one coherent story that is consistent with the presence of a large impact crater on the far side of the asteroid," says co-author Michael Küppers, from ESA's Space Astronomy Centre in Spain.

"Four years on and we are delighted still to be learning from just two hours' worth of data collected during the Lutetia flyby," says Matt Taylor, ESA's Rosetta project scientist.

"Rosetta is now in its main mission phase at its comet, where we are on the cusp of fantastic results. Rosetta is a true small bodies mission, two asteroids and one comet in single trip."

More information: S. Besse, M. Küppers, O.S. Barnouin, N. Thomas, J. Benkhoff, "Lutetia׳s lineaments," Planetary and Space Science, Volume 101, 15 October 2014, Pages 186-195, ISSN 0032-0633, dx.doi.org/10.1016/j.pss.2014.07.007

ESA Rosetta: jets of dust and outgassing from Comet 67/P

An image taken by ESA's Rosetta probe on Sept. 26, 2014 shows jets of dust and gas escaping from the nucleus of Comet 67P/Churyumov-Gerasimenko.

Credit: ESA/Rosetta/NAVCAM

A European spacecraft's comet companion is starting to wake up as it gets closer and closer to the sun.

The European Space Agency's Rosetta probe, which arrived in orbit around Comet 67P/Churyumov-Gerasimenko in August after a 10-year deep-space chase, has photographed jets of gas and dust erupting from the icy wanderer's surface.

"The main talking point of this image is the spectacular region of activity at the neck of 67P/C-G," European Space Agency (ESA) officials wrote in a description of the photo, a four-image montage taken on Sept. 26 when Rosetta was 16 miles (26 kilometers) from the comet.

"What we’re seeing is the product of ices sublimating and gases escaping from inside the comet, carrying streams of dust out into space," they added.

"As the comet gets progressively closer to the sun along its orbit, the surface will become warmer, and the level of activity will increase, producing a vast coma around the nucleus, along with a tail."

The $1.7 billion (1.3 billion euros) Rosetta mission launched in March 2004 and took a circuitous path through space, finally catching up to the 2.5-mile-wide (4 km) Comet 67P on Aug. 6 of this year. On that date, Rosetta became the first probe ever to orbit a comet.

The Rosetta team aims to make some more history soon. On Nov. 12, the probe will deploy a lander called Philae, which will spiral slowly down toward 67P and, if all goes according to plan, become the first robot to make a soft touchdown on a comet.

Philae will snap photos and analyze samples of the comet.

Rosetta should continue studying 67P through at least December 2015, observing how the icy body changes as it approaches the sun.