[Graeme]

First Close-Up Photos Of The Solar System's "Most Crazy Bonkers Comet"

In March 2004, ESA's Rosetta spacecraft left Earth in pursuit of comet 67P/Churyumov-Gerasimenko. Today, more than 10 years and four billion miles later, Rosetta became the first spacecraft in history to rendezvous with a comet. The probe is now soaring through space in tandem with its target – and the view is incredible.

Rosetta is currently flying in front of the comet, mapping its gravitational fields. In the coming weeks, Rosetta will settle into 67P's orbit. It will do so at a distance of around 30 kilometers at first, but will slowly circle in closer. In November, from a projected orbital distance of just 2.5 km, Rosetta will deposit a lander on the comet's surface – all this in preparation for 67P's closest pass of the Sun in more than six years. As it swings around our parent star, the mass of ice and dust will warm, shedding bits of itself along the way; Rosetta – and Philae, the lander – will have unprecedented front row seats to the show.

All that, of course, is yet to come. In the meantime, Rosetta is capturing some of the most detailed views of a comet's surface we've ever seen. Pictures released this morning show the rubber ducky–shaped comet in all its lopsided glory, and some hi-res surface images of what ESA senior scientist Mark McCaughrean called "the most crazy bonkers comet in the solar system":

io9

[Tanada]

I clarified the thread Title to make it easier for people searching in the future.

More detailed data will be gathered by VIRTIS -- and Rosetta's 10 other experiments -- after the spacecraft arrives close up to the comet Aug. 6.

"This doesn't exclude the presence of patches of relatively clean ice, however, and very soon, VIRTIS will be able to start generating maps showing the temperature of individual features," Capaccioni said.

Rosetta's navigation camera and main science camera have collected more detailed imagery of the comet throughout the approach phase, which began in January when engineers awakened the probe from a nearly three-year deep space power-saving hibernation.

The images show the comet is made up of two distinct lobes connected with a narrow collar-like neck.

Much longer article and several pictures at the link,

http://spaceflightnow.com/rosetta/14080 ... -LilKNRrts

[Graeme]

T, Thanks for the editing and your interest. I found more info here including more images and a 3D view:

After a journey of more than a decade, Rosetta has finally arrived at comet 67P Churyumov-Gerasimenko. Confirmation of the successful rocket firing came at about 9:30 UTC via a webcast from ESA's Operations Centre in Darmstadt, Germany. Congratulations to ESA, to the scientists and engineers on the mission, and all the people of all of ESA's member nations!

To celebrate the arrival, they released this photo of the comet taken three days ago, from a distance of 285 kilometers. The spacecraft is now three times closer, on an odd triangle-shaped orbit, so even better photos are yet to come. I have been adding new images and information to this post all morning. A more detailed report on the day's press events by Daniel Fischer will be posted later today.

[Subjectivist]

The European Space Agency has put several videos up on YouTube, here is a good one released yesterday.

http://youtu.be/MBGICP1P32w

[Synapsid]

"...on an odd triangle-shaped orbit..."

"Odd" would scarcely do it justice. Celestial mechanics--out the window wi' ye!

[Tanada]

"...on an odd triangle-shaped orbit..."

"Odd" would scarcely do it justice. Celestial mechanics--out the window wi' ye!

Technically it what used to be called a forced orbit, the gravity field of the body being circled is not strong enough to keep it in a circle so the rockets fire every so often to put it back on the path around. You can even force a circular orbit with a constant low power burn, but unless the satellite is made specifically for that purpose you end up wasting a huge amount of fuel. The triangle orbit is the lowest energy expenditure version of a forced orbit, the more sides you have in the shape the more times you have to fire the rockets.

[Graeme]

As seen by Rosetta: Comet surface variations

A new 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-wide (4-kilometer) nucleus.

In the image, the comet's head (in the top half of the image) exhibits parallel linear features that resemble cliffs, and its neck displays scattered boulders on a relatively smooth, slumping surface. In comparison, the comet's body (lower half of the image) seems to exhibit a multi-variable terrain with peaks and valleys, and both smooth and rough topographic features.

A 3-D version of the image depicting the comet is available at: http://go.nasa.gov/1t3K3FU

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 are to study comet 67P/Churyumov-Gerasimenko up close in unprecedented detail, prepare for landing a probe on the comet's nucleus in November, and track its changes as it sweeps past the sun.

sciencedaily

[Tanada]

ESA has a blog dedicated to the mission with both commentary and photo's

http://blogs.esa.int/rosetta/2014/08/17 ... 16-august/

[Timo]

This is incredibly exciting and interesting. However, all of this does lead to the inevitable and requisite question if there's any He3 on that sucker that can be brought back to earth and used for fusion purposes.

Sorry, but someone had to do that. I know KJ at least thought of that question.

[Keith_McClary]

Los Angeles
http://boingboing.net/2014/08/21/how-bi ... geras.html

[Graeme]

Rosetta: Landing Site Search Narrows

The European Space Agency's Rosetta mission has chosen five candidate landing sites on comet 67P/Churyumov-Gerasimenko for its Philae lander. Philae's descent to the comet's nucleus, scheduled for this November, will be the first such landing ever attempted. Rosetta is an international mission spearheaded by the European Space Agency with support and instruments provided by NASA.

Choosing the right landing site is a complex process. It must balance the technical needs of the orbiter and lander during all phases of the separation, descent and landing, and during operations on the surface, with the scientific requirements of the 10 instruments on board Philae. A key issue is that uncertainties in navigating the orbiter close to the comet mean that it is possible to specify any given landing zone only in terms of an ellipse - covering up to six-tenths of a square mile (one square kilometer) - within which Philae might land.

jpl

[Keith_McClary]

Images reveal breathtaking world on Rosetta's comet

A preliminary map of Rosetta’s comet has revealed a multifaceted world consisting of cliffs, depressions, craters, and boulders, the Max Planck Institute for Solar System Research reports. The OSIRIS imaging system aboard the Rosetta spacecraft, which arrived at the comet 67P/Churyumov-Gerasimenko about a month ago, has produced images of unprecedented resolution, with one pixel corresponding to 75 centimeters on the nucleus in some cases, researcher report today at the European Planetary Science Congress 2014. Based on these images, scientists have divided the comet’s surface into several distinct geographical regions for further analysis. They will monitor the comet’s surface closely in the next few months, as both 67P and Rosetta travel closer to the sun, for any changes that might help explain how the comet’s activity shaped its surface.
http://news.sciencemag.org/sifter/2014/ ... ta-s-comet

[Tanada]

Nice imagery. So far as I can tell the landing is still planned for Veterans/Armistice day, November 11, 2014.

[Tanada]

European scientists have selected an aim point for the landing of Philae, a small probe riding piggyback on the Rosetta spacecraft set for the first-ever descent to a comet's nucleus in November.

The task will not be easy, but officials said Monday they chose the best possible location for the landing on comet 67P/Churyumov-Gerasimenko, an object covered with craggy terrain, rifts and cliffs, and jets of vapor and dust that will become more prominent as the comet dives closer to the sun over the next 11 months.

Scientists say combining data from Rosetta and the Philae lander will provide an unprecedented glimpse of a comet's behavior, yielding insights into the building blocks left over from the formation of the solar system 4.5 billion years ago.

Researchers believe comets may have seeded Earth with water and organic material, depositing the materials necessary for life.

Philae's landing location, known as Site J during lander team's deliberations, is on the small lobe of the comet, which is made up of two distinct segments connected by a narrow neck.

"There are flat areas, but there is also rough terrain," said Stephan Ulamec, head of the Philae lander team at DLR, the German Aerospace Center. "There are some cliffs. There are some boulders, so we have to work a little bit with statistics. It is not a perfectly flat area as we probably would have hoped for a safe landing site."

Landing is set for Nov. 11, following a descent of approximately seven hours once Philae is released from the Rosetta mothership, which arrived at the comet Aug. 6 and has moved within 30 kilometers, or about 18 miles, of 67P/Churyumov-Gerasimenko in the last few weeks.

The lander will be passive and on its own during the free fall to the comet, so engineers on Earth must put the Rosetta spacecraft in the correct position and orientation for separation of Philae.

"We need both Rosetta and Philae in synchronization," said Andrea Accomazzo, flight director for the Rosetta mission at the European Space Operations Center in Darmstadt, Germany. "We need very accurate navigation with Rosetta. This is the most challenging part."


Artist's concept of the Philae lander on the comet. Credit: ESA

The comet's tenuous gravity field makes it difficult to predict Rosetta's orbit around the nucleus, requiring rocket burns to adjust its path.

Thanks to the weak gravity, Ulamec said the 100-kilogram (220-pound) Philae lander will weigh just a gram on the comet. Its mission will last at least two days, but could stretch into early 2015 if the probe's battery can be recharged with solar energy.

Data from the lander will be routed though the Rosetta orbiter and back to Earth, so the mothership must be regularly in view of the landing site, including at the time of touchdown.

After deploying three landing legs fitted with shock absorbers, Philae will hit the comet at about a walking pace, fire a harpoon into the ground to prevent the lander from bouncing off, then screw into rock to firmly attach itself for at least two days of photo-taking, drilling, measurements and other science activities.

Speaking with reporters in a press conference in Paris on Monday, mission officials cautioned the endeavor was fraught with risk, mainly because comet 67P/Churyumov-Gerasimenko is covered in hazards, ranging from unstable, gravely pits to steep slopes and boulders.

"When we designed the lander 15 or 20 years ago, we had no idea of the target body," Ulamec said. "We had no idea of the size, no idea of the gravity, and no idea of the shape or the surface properties. We were even designing it for a different comet. This is completely different than missions that land on the moon or Mars, where you have all this data so you know what you're dealing with."

Armed only with imagery and data collected in the last few months -- once Rosetta was close enough to study the comet in detail -- scientists met last weekend in Toulouse, France, to go over five candidate landing sites.

The decision in favor of Site J as the primary landing site was unanimous, according to a European Space Agency press release. Officials chose a backup site, known as Site C, on the larger lobe of the comet.

More at the link, including a couple pictures.
http://www.astronomynow.com/news/n1409/ ... EEBA2c8O1c

[Graeme]

Comet stinks of rotten eggs and cat wee, finds Rosetta

What does a comet smell like? Pretty awful, as it turns out. Data from the European Space Agency's Rosetta probe has revealed that eau de comet 67P/Churyumov-Gerasimenko is a mixture of rotten eggs, cat urine and bitter almonds.

This bad smell is actually good news. The molecules behind the odours – hydrogen sulphide, ammonia and hydrogen cyanide – are mixed up with frozen water and carbon dioxide, so Rosetta's spectrometers weren't expected to detect such a variety until the comet approached the sun and warmed up. Formaldehyde, methanol and sulphur dioxide are also in the mix.

"It's really fabulous. You wait 10 years and all of a sudden it's there," says Kathrin Altwegg of the University of Bern in Switzerland, who is in charge of Rosetta's electronic nose, otherwise known as the Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA). "What's surprising is we already have extremely rich chemistry at this distance from the sun."

When the icy comet heats up further, ROSINA will be able to detect more complex molecules. Altwegg will compare the comet's molecular make-up to that of other known ice balls in an attempt to determine whether they have a common origin.

Comets are the leftover building blocks from the earlier days of the solar system, and one of the aims for Rosetta is to identify whether they are all made from the same stuff Movie Camera. If some comets differ, that could explain the origin of molecules required to start life on Earth.

As for that smell, the molecules are in very low concentrations so a human standing on 67P probably wouldn't notice the odour, says Altwegg. "You would probably need a good dog to smell it."

newscientist

[Deputy Barnes]

Clearly an alien spaceship; laughable attempts by nerds to cover it up.

[Tanada]

The comet lander is on its way!

A potential problem with a rocket thruster designed to keep the Philae lander from bouncing off comet 67P/Churyumov-Gerasimenko after touchdown Wednesday will make the probe’s daring descent even more challenging, officials said.

The cold gas propulsion system, mounted on the top side of the oven-sized Philae lander, is supposed to engage and keep the spacecraft on the comet’s surface while it fires two harpoon anchors to mount itself on the surface.

“We do have a problem with the cold gas system on-board the lander, but everything else is nominal and everything is go,” said Stephan Ulamec, who leads the Philae lander team at DLR, the German Aerospace Center.

Engineers devised the cold gas thruster to counteract the impulse of the firing of the harpoons, which could nudge the lander off the comet after it descends from the European Space Agency’s Rosetta orbiter.

The lander carries the nitrogen-fueled cold gas thruster and harpoons to affix itself to the comet’s nucleus as soon as it detects its three legs have contacted the surface. The comet’s feeble gravity — one hundred thousand times weaker than Earth’s — is not strong enough for the lander to plop down on the ground like a landing on a planet.

The comet measures around 4.5 miles long and 3 miles wide — about the size of a small city.

“This will make the landing even more challenging now because we cannot operate this pressure on the surface to avoid the re-bounce,” Ulamec said. “We have to fully rely now on the harpoons.”

Each landing leg also has ice screws to bore into the nucleus to add more stability after landing.

More plus a picture or two at the link,
http://spaceflightnow.com/2014/11/12/co ... r-problem/

[Keith_McClary]

Successful landing despite thruster problem.
Leaked photo reveals true reason for Philae comet landing mission