News of the Comet-hunting Rosetta mission

[Rick]

Rosetta's MIRO Instrument Maps Comet Water

Since last September, scientists using NASA's Microwave Instrument for Rosetta Orbiter (MIRO) on the European Space Agency's Rosetta spacecraft have generated maps of the distribution of water in the coma of comet 67P/Churyumov-Gerasimenko, as the comet's orbit brings it closer to the sun.

MIRO is able to detect water in the coma by measuring the direct emission from water vapor in the coma and by observing absorption of radiation from the nucleus at water-specific frequencies as the radiation passed through the coma.

On Sept. 7, 2014, when Rosetta was 36 miles (58 kilometers) from the center of the comet, the MIRO team obtained their first map of the nucleus of 67P/C-G and its surroundings. They discovered the highest density of water just above the comet's neck, close to the north pole of the comet's rotation axis. In this narrow region, the number of water molecules is up to two orders of magnitude higher than elsewhere in the coma. Lower but still substantial amounts of water were detected over on the day side of the nucleus up to the terminator between the illuminated and dark side. The lowest amounts of water are found on the comet's night side -- particularly over its southern polar regions. This could be due to either local outgassing or circulation effects within the coma, causing water to flow from the day to the night side.

More: http://www.jpl.nasa.gov/news/news.php?feature=4632

[Rick]

Comet Sinkholes Generates Jets

A number of the dust jets emerging from Rosetta's comet can be traced back to active pits that were likely formed by a sudden collapse of the surface. These 'sinkholes' are providing a glimpse at the chaotic and diverse interior of the comet.

Rosetta has been monitoring Comet 67P/Churyumov–Gerasimenko's activity for over a year, watching how its halo of dust and gas grows as the comet moves closer to the Sun along its orbit.

From a distance of a few hundred kilometres, Rosetta observes an intricate pattern of the dust jets emitted from the nucleus as they stream out into space. But now, thanks to high-resolution images from the OSIRIS camera from distances of just 10–30 km from the comet centre last year, at least some of these dust jets can be traced back to specific locations on the surface, the first time this has ever been seen.

More from ESA

[Rick]

New Communication with Philae - Commands Executed Successfully

The Philae lander communicated with the Rosetta orbiter again between 19:45 and 20:07 CEST on 9 July 2015 and transmitted measurement data from the COmet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) instrument. Although the connection failed repeatedly after that, it remained completely stable for those 12 minutes. "This sign of life from Philae proves to us that at least one of the lander's communication units remains operational and receives our commands," said Koen Geurts, a member of the lander control team at DLR Cologne.

The mood had been mixed over the last few days; Philae had not communicated with the team in the DLR Lander Control Center (LCC) since 24 June 2015. After an initial test command to turn on the power to CONSERT on 5 July 2015, the lander did not respond. Philae's team began to wonder if the lander had survived on Comet 67P/Churyumov-Gerasimenko.

"We never gave up on Philae and remained optimistic," said Geurts. There was great excitement when Philae 'reported in' on 13 June 2015 after seven months of hibernation and sent data about its health. The lander was ready to perform its tasks, 300 million kilometres away from Earth.

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[Rick]

Science on a Surface of a Comet (Rosetta/Philae)

Complex molecules that could be key building blocks of life, the daily rise and fall of temperature, and an assessment of the surface properties and internal structure of the comet are just some of the highlights of the first scientific analysis of the data returned by Rosetta's lander Philae last November.

Early results from Philae's first suite of scientific observations of Comet 67P/Churyumov­-Gerasimenko were published today in a special edition of the journal Science.

Data were obtained during the lander's seven-hour descent to its first touchdown at the Agilkia landing site, which then triggered the start of a sequence of predefined experiments. But shortly after touchdown, it became apparent that Philae had rebounded and so a number of measurements were carried out as the lander took flight for an additional two hours some 100 m above the comet, before finally landing at Abydos.

Some 80% of the first science sequence was completed in the 64 hours following separation before Philae fell into hibernation, with the unexpected bonus that data were ultimately collected at more than one location, allowing comparisons between the touchdown sites.

More: http://sci.esa.int/rosetta/56250-science-on-the-surface-of-a-comet/

[Rick]

Rosetta Comet Outburst Captured

The European Space Agency's Rosetta spacecraft has been witnessing growing activity from comet 67P/Churyumov-Gerasimenko as the comet approaches perihelion (its closest point to the sun during its orbit). On July 29, while the spacecraft orbited at a distance of 116 miles (186 kilometers) from the comet, it observed the most dramatic outburst to date. Early science results collected during the outburst came from several instruments aboard Rosetta, including the Double Focusing Mass Spectrometer (DFMS), which uses NASA-built electronics. The DFMS is part of the spacecraft's Rosetta Orbiter Spectrometer for Ion and Neutral Analysis (ROSINA) instrument.

When the outburst occurred, the spectrometer recorded dramatic changes in the composition of outpouring gases from the comet when compared to measurements made two days earlier. As a result of the outburst, the amount of carbon dioxide increased by a factor of two, methane by four, and hydrogen sulfide by seven, while the amount of water stayed almost constant.

More: http://www.jpl.nasa.gov/news/news.php?feature=4687

[Rick]

Comet Surface Changes Before Rosetta's Eyes

Since arriving at Comet 67P/C-G in August 2014, Rosetta has been witnessing an increase in the activity of the comet, warmed by the ever-closer Sun. A general increase in the outflow of gas and dust has been punctuated by the emergence of jets and dramatic rapid outbursts in the weeks around perihelion, the closest point to the Sun on the comet's orbit, which occurred on 13 August 2015.

But in June 2015, just two months before perihelion, Rosetta scientists started noticing important changes on the surface of the nucleus itself. These very significant alterations have been seen in Imhotep, a region containing smooth terrains covered by fine-grained material as well as large boulders, located on 67P/C-G's large lobe.

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[Rick]

Rosetta reveals comet's water-ice cycle

A key feature that Rosetta's scientists are investigating is the way in which activity on the comet and the associated outgassing are driven, by monitoring the increasing activity on and around the comet since Rosetta's arrival.

Scientists using Rosetta's Visible, InfraRed and Thermal Imaging Spectrometer, VIRTIS, have identified a region on the comet's surface where water ice appears and disappears in sync with its rotation period. Their findings are published today in the journal Nature.

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[Rick]

First Detection of Molecular Oxygen At A Comet

ESA's Rosetta spacecraft has made the first in situ detection of oxygen molecules outgassing from a comet, a surprising observation that suggests they were incorporated into the comet during its formation.

Rosetta has been studying Comet 67P/Churyumov-Gerasimenko for over a year and has detected an abundance of different gases pouring from its nucleus. Water vapour, carbon monoxide and carbon dioxide are the most prolific, with a rich array of other nitrogen-, sulphur- and carbon-bearing species, and even 'noble gases' also recorded.

Oxygen is the third most abundant element in the Universe, but the simplest molecular version of the gas, O2, has proven surprisingly hard to track down, even in star-forming clouds, because it is highly reactive and readily breaks apart to bind with other atoms and molecules.

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[Rick]

Rosetta Finds Magnetic Field-Free Bubble at Comet

ESA's Rosetta spacecraft has revealed a surprisingly large region around its host comet devoid of any magnetic field.

When ESA's Giotto flew past Comet Halley three decades ago, it found a vast magnetic-free region extending more than 4000 km from the nucleus. This was the first observation of something that scientists had until then only thought about but had never seen.

Interplanetary space is pervaded by the solar wind, a flow of electrically charged particles streaming from the Sun and carrying its magnetic field across the Solar System. But a comet pouring lots of gas into space obstructs the solar wind.

t the interface between the solar wind and the coma of gas around the active comet, particle collisions as well as sunlight can knock out electrons from the molecules in the coma, which are ionised and picked up by the solar wind. This process slows the solar wind, diverting its flow around the comet and preventing it from directly impacting the nucleus.

More from ESA

[JohnP]

Philae found.. hooraaaa...!

Less than a month before the end of the mission, Rosetta's high-resolution camera has revealed the Philae lander wedged into a dark crack on Comet 67P/Churyumov–Gerasimenko.

The images were taken on 2 September by the OSIRIS narrow-angle camera as the orbiter came within 2.7 km of the surface and clearly show the main body of the lander, along with two of its three legs.

The images also provide proof of Philae's orientation, making it clear why establishing communications was so difficult following its landing on 12 November 2014.

More: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Philae_found

[Mike]

yay!! \o/

Download the High-Res image from here and look at the amazing crumbly texture of the comet....

http://www.esa.int/spaceinimages/Images/2016/09/Philae_found

[Carole]

OMG that is so tiny to be able to spot.

Amazing mission

Carole

[Rick]

NASA's Kepler Gets the 'Big Picture' of Comet 67P

On Sept. 30, the European Space Agency concluded its Rosetta mission and the study of comet 67P/Churyumov-Gerasimenko. During the final month of the mission, NASA's planet-hunting Kepler spacecraft had a unique opportunity to provide a "big picture" view of the comet as it was unobservable from Earth. Ground-based telescopes could not see comet 67P, because the comet's orbit placed it in the sky during daylight hours.

From Sept. 7 through Sept. 20, the Kepler spacecraft, operating in its K2 mission, fixed its gaze on comet 67P. From the distant vantage point of Kepler, the spacecraft could observe the comet's core and tail. The long-range global view of Kepler complements the close-in view of the Rosetta spacecraft, providing context for the high-resolution investigation Rosetta performed as it descended closer and closer to the comet.

During the two-week period of study, Kepler took a picture of the comet every 30 minutes. The animation shows a period of 29.5 hours of observation from Sept. 17 through Sept. 18. The comet is seen passing through Kepler's field of view from top right to bottom left, as outlined by the diagonal strip. The white dots represent stars and other regions in space studied during K2's tenth observing campaign.

More: http://www.jpl.nasa.gov/news/news.php?feature=6641

[Rick]

The Many Faces of Rosetta's Comet 67P

Images returned from the European Space Agency's Rosetta mission indicate that during its most recent trip through the inner solar system, the surface of comet 67P/Churyumov-Gerasimenko was a very active place - full of growing fractures, collapsing cliffs and massive rolling boulders. Moving material buried some features on the comet's surface while exhuming others. A study on 67P's changing surface was released Tuesday, March 21, in the journal Science.

"As comets approach the sun, they go into overdrive and exhibit spectacular changes on their surface," said Ramy El-Maarry, study leader and a member of the U.S. Rosetta science team from the University of Colorado, Boulder. "This is something we were not able to really appreciate before the Rosetta mission, which gave us the chance to look at a comet in ultra-high resolution for more than two years."

More: https://www.jpl.nasa.gov/news/news.php?feature=6786

[Carole]

Not sure which section to post this in.

Fantastic video taken from Rosetta mission:

https://vimeo.com/347565673