Using a Sounding Rocket to Help Calibrate NASA's SDO

FOXSI Sounding Rocket logo / NASA Solar Dynamics Observatory (SDO) patch.

May 19, 2015

FOXSI Sounding Rocket Description. Graphic Credits: NASA/ GFSC

Watching the sun is dangerous work for a telescope. Solar instruments in space naturally degrade over time, bombarded by a constant stream of solar particles that can cause a film of material to adhere to the optics. Decades of research and engineering skill have improved protecting such optics, but one crucial solution is to regularly recalibrate the instruments to accommodate such changes.

In mid-May, the seventh calibration mission for an instrument on NASA's Solar Dynamics Observatory, or SDO, will launch into space onboard a sounding rocket for a 15-minute flight. The instrument to be calibrated is called EVE, short for the EUV Variability Experiment, where EUV stands for extreme ultraviolet. EVE's job is to observe the total energy output of the sun in EUV light waves. The calibration mission is scheduled to launch on May 21, 2015, on a Terrier-Black Brant suborbital sounding rocket around 3 pm EDT from White Sands Missile Range, New Mexico.

"Parts of the optical coating can darken due to exposure to solar ultraviolet radiation and high energy particles in space, so the sensitivity of the EVE detector decreases over time," said Tom Woods, the principal investigator for this calibration mission as well as for EVE at the University of Colorado in Boulder. "By determining how much the instrument has degraded since last time, we can adjust data processing algorithms to account for that change."

EVE measures the total energy output of the sun, known as irradiance, for each wavelength of light in the extreme ultraviolet range. By tracking the irradiance, scientists can observe how it changes with different events on the sun. None of these wavelengths can penetrate Earth's atmosphere to reach humans on Earth, but each can have a profound effect on the air above our planet. Some of this light energy gets absorbed in the thermosphere, causing it to expand like a balloon when heated, which can create more drag on satellites in space. Other wavelengths of extreme ultraviolet light can have an effect on the composition of the charged ions in Earth's ionosphere, which can hinder radio communications or GPS navigation systems.

What's more, the total amount of each kind of light changes in different ways based on what's happening on the sun, including such things as the approximately 11-year solar cycle during which the sun ramps up to a time of more eruptions and magnetic activity – called solar maximum – and back down again to the quiet of solar minimum. While one wavelength of light might increase only by about 60 percent over this solar cycle, another wavelength might grow to be 100 times stronger. As scientists seek to understand how changes on the sun affect our home planet, they need to parse out the details of what causes an increase in the different kinds of light waves.

"We also study irradiance to better understand what types of energy the sun sends out during an eruption like a solar flare," said Woods. "We have used EVE to better categorize the phases of flares --  – one of the discoveries is that there are peaks in the extreme ultraviolet emissions that occur one to five hours after the flare appears in X-ray images."

All of this research about events on the sun and potential effects at Earth, depend on accurate measurements of the total solar energy output. This, in turn, leads to the job of calibrating EVE approximately once a year. While launched with EVE in mind, the May sounding rocket will also, in fact, serve as a calibration tool for a number of solar EUV instruments currently in space.

The calibration mission flight lasts for approximately 15 minutes, affording five minutes of prime solar viewing time. Such short sounding rocket flights allow for solid research via relatively low-cost access to space.

The EVE calibration mission is supported through NASA’s Sounding Rocket Program at the Goddard Space Flight Center’s Wallops Flight Facility in Virginia. NASA’s Heliophysics Division manages the sounding rocket program.

Lateral right graphic: Earth's atmosphere consists of different layers made of different particles. The sun emits a variety of wavelengths of extreme ultraviolet light, which can each affect these layers in different ways. Graphic Credit: NASA.

For more information about Solar Dynamics Observatory (SDO) mission, visit: http://sdo.gsfc.nasa.gov/ and http://www.nasa.gov/mission_pages/sdo/main/index.html

For more information about FOXSI sounding rocket, visit: https://www.ssl.berkeley.edu/foxsi-sounding-rocket-launch/

Graphics (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Karen C. Fox/ Holly Zell.

Best regards, Orbiter.ch

NASA Soil Moisture Mission Begins Science Operations

NASA - Soil Moisture Active Passive (SMAP) patch.

May 19, 2015

NASA's new Soil Moisture Active Passive (SMAP) mission to map global soil moisture and detect whether soils are frozen or thawed has begun science operations.

Launched Jan. 31 on a minimum three-year mission, SMAP will help scientists understand links among Earth's water, energy and carbon cycles; reduce uncertainties in predicting climate; and enhance our ability to monitor and predict natural hazards like floods and droughts. SMAP data have additional practical applications, including improved weather forecasting and crop yield predictions.

Image above: High-resolution global soil moisture map from SMAP's combined radar and radiometer instruments, acquired between May 4 and May 11, 2015, during SMAP's commissioning phase. The map has a resolution of 5.6 miles (9 kilometers). Image Credits: NASA/JPL-Caltech/GSFC.

During SMAP's first three months in orbit, referred to as SMAP's "commissioning" phase, the observatory was first exposed to the space environment, its solar array and reflector boom assembly containing SMAP's 20-foot (6-meter) reflector antenna were deployed, and the antenna and instruments were spun up to their full speed, enabling global measurements every two to three days.

The commissioning phase also was used to ensure that SMAP science data reliably flow from its instruments to science data processing facilities at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California, and the agency’s Goddard Space Flight Center in Greenbelt, Maryland.

"Fourteen years after the concept for a NASA mission to map global soil moisture was first proposed, SMAP now has formally transitioned to routine science operations," said Kent Kellogg, SMAP project manager at JPL. "SMAP's science team can now begin the important task of calibrating the observatory's science data products to ensure SMAP is meeting its requirements for measurement accuracy."

Together, SMAP's two instruments, which share a common antenna, produce the highest-resolution, most accurate soil moisture maps ever obtained from space. The spacecraft’s radar transmits microwave pulses to the ground and measures the strength of the signals that bounce back from Earth, whereas its radiometer measures microwaves that are naturally emitted from Earth’s surface.

Images above: Southern U.S. SMAP soil moisture retrievals from April 27, 2015, when severe storms were affecting Texas. Top: radiometer data alone. Bottom: combined radar and radiometer data with a resolution of 5.6 miles (9 kilometers). Image Credits: NASA/JPL-Caltech/GSFC.

"SMAP data will eventually reveal how soil moisture conditions are changing over time in response to climate and how this impacts regional water availability,” said Dara Entekhabi, SMAP science team leader at the Massachusetts Institute of Technology in Cambridge. “SMAP data will be combined with data from other missions like NASA's Global Precipitation Measurement, Aquarius and Gravity Recovery and Climate Experiment to reveal deeper insights into how the water cycle is evolving at global and regional scales."

The first global view of SMAP's flagship product, a combined active-passive soil moisture map with a spatial resolution of 5.6 miles (9 kilometers), shows dry conditions in the Southwestern United States and in Australia's interior. Moist soil conditions are evident in the U.S. Midwest and in eastern regions of the United States, Europe and Asia. The far northern regions depicted in these SMAP maps do not indicate soil moisture measurements because the ground there was frozen.

Zooming in on the data allows a closer look at the benefits of combining SMAP's radar and radiometer data. A few days before SMAP collected data over the central and southern United States on April 27, intense rainstorms pounded northern Texas. The areas affected by the storm in northern Texas and the Gulf Coast are visible in great detail. Such detail can be used to improve local weather forecasts, assist in monitoring drought in smaller watersheds, and forecast floods.

Image above:  Artist’s rendering of NASA's Soil Moisture Active Passive (SMAP) spacecraft in orbit. Image Credit: NASA.

Over the next year, SMAP data will be calibrated and validated by comparing it against ground measurements of soil moisture and freeze/thaw state around the world at sites representing a broad spectrum of soil types, topography, vegetation and ground cover. SMAP data also will be compared with soil moisture data from existing aircraft-mounted instruments and other satellites.

Preliminary calibrated data will be available in August at designated public-access data archives, including the National Snow and Ice Data Center in Boulder, Colorado, and Alaska Satellite Facility in Fairbanks. Preliminary soil moisture and freeze/thaw products will be available in November, with validated measurements scheduled to be available for use by the general science community in the summer of 2016.

NASA uses the vantage point of space to increase our understanding of our home planet, improve lives, and safeguard our future. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records. The agency freely shares this unique knowledge and works with institutions around the world to gain new insights into how our planet is changing.

For more information on SMAP, visit: http://www.nasa.gov/smap

For more information about NASA's Earth science activities, visit: http://www.nasa.gov/earth

Images (mentioned), Text, Credits: NASA/Steve Cole/JPL/Alan Buis/Karen Northon.

Greetings, Orbiter.ch

CMS and LHCb experiments reveal new rare particle decay

CERN - European Organization for Nuclear Research logo.

May 18, 2015

Image above: Event display of a candidate B⁰_s particle decaying into two muons in the LHCb detector. (Image: LHCb/CERN).

In an article published today in Nature, the CMS and LHCb collaborations describe the first observation of the very rare decay of the B⁰_s particle into two muon particles. The Standard Model, the theory that best describes the world of particles, predicts that this rare subatomic process happens about four times out of a billion decays, but it has never been seen before. The analysis is based on data taken at the Large Hadron Collider (LHC) in 2011 and 2012. These data also contain hints of a similar, but even more rare decay of the B⁰, a cousin of the B⁰_s.

Image above: Event display of a candidate B⁰_s decay into two muons in the CMS detector. (Image: CMS event display/CERN).

The B⁰_s and B⁰ are mesons, non-elementary unstable subatomic particles composed of a quark and an antiquark, bound together by the strong interaction. Such particles are produced only in high-energy collisions – at particle accelerators, or in nature, for example in cosmic-ray interactions. This result has important implications in the search for physics beyond the Standard Model.

Developed in the early 1970s, the Standard Model is currently the best description of the subatomic world. It has successfully explained almost all experimental results in particle physics and precisely predicted a wide variety of phenomena. However, it doesn’t answer some important questions such as “What is dark matter?” or “What happened to the antimatter after the big bang?”.

That is why LHC experiments are trying to find hints of “new” physics, which would solve some of these enigmas. There are two complementary strategies to probe this physics “beyond” the Standard Model, which are both employed by the experiments at the LHC. The direct one, which consists in looking for new particles predicted by theoretical models that go beyond the Standard Model, such as supersymmetry, and the indirect one, which challenges the Standard Model on its predictions for very rare decays. Any discrepancy between the experimental results on these very rare processes and the Standard Model’s predictions would point to signs of new physics. This is the strategy adopted by the LHCb and CMS experiments in studying the rare decays of the B⁰_s and the B⁰ particles into two muons.

Large Hadron Collider (LHC) at CERN. Image Credit: CERN

The CMS and LHCb collaborations first released their individual results for B⁰s meson decay in July 2013. While the results were in excellent agreement, both fell just below the 5 sigma statistical precision historically needed to claim an observation. The combined analysis easily exceeds this requirement, reaching 6.2 sigma. This is the first time that CMS and LHCb have analysed their data together.

This combined analysis shows that the probability for a B⁰s meson to decay into two muons, and the probability for a B⁰ meson to decay into two muons, are consistent with the Standard Model's predictions. So at least, for now, these rare decays have not revealed any hints of new physics. However, the data to be gathered in future runs of the LHC will increase the precision of the B⁰s measurement and will determine whether the possible hints of the related decay of the B⁰ are confirmed. These results will be crucial for disentangling any signs of new phenomena from Standard Model effects and will advance the hunt for new physics.

Note:

CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Its business is fundamental physics, finding out what the Universe is made of and how it works. At CERN, the world’s largest and most complex scientific instruments are used to study the basic constituents of matter — the fundamental particles. By studying what happens when these particles collide, physicists learn about the laws of Nature.

The instruments used at CERN are particle accelerators and detectors. Accelerators boost beams of particles to high energies before they are made to collide with each other or with stationary targets. Detectors observe and record the results of these collisions.

Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 22 Member States.

Read the Press Release: http://press.web.cern.ch/press-releases/2015/05/cms-and-lhcb-experiments-reveal-new-rare-particle-decay#overlay-context=

Read the LHCb article: http://lhcb-public.web.cern.ch/lhcb-public/Welcome.html#LHCbCMS

Read the CMS update: http://cms.web.cern.ch/news/very-rare-decay-has-been-seen-cms

Read the publication in Nature: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature14474.html

Related links:

Large Hadron Collider (LHC): http://home.web.cern.ch/topics/large-hadron-collider

CMS experiments: http://home.web.cern.ch/about/experiments/cms

LHCb experiments: http://home.web.cern.ch/about/experiments/lhcb

Physics Standard Model: http://home.web.cern.ch/about/physics/standard-model

For more information about the European Organization for Nuclear Research (CERN), visit: http://home.web.cern.ch/

Images (mentioned), Text, Credits: CERN/Corinne Pralavorio.

Cheers, Orbiter.ch

Janus Stands Alone

NASA - Cassini Mission to Saturn patch.

May 18, 2015

Although Janus should be the least lonely of all moons - sharing its orbit with Epimetheus - it still spends most of its orbit far from other moons, alone in the vastness of space.

Janus (111 miles or 179 kilometers across) and Epimetheus have the same average distance from Saturn, but they take turns being a little closer or a little farther from Saturn, swapping positions approximately every 4 years. See PIA08348 for more.

This view looks toward the sunlit side of the rings from about 19 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Feb. 4, 2015.

The view was acquired at a distance of approximately 1.6 million miles (2.5 million kilometers) from Janus and at a Sun-Janus-spacecraft, or phase, angle of 91 degrees. Image scale is 9 miles (15 kilometers) per pixel.

Artist's view of the Cassini spacecraft orbiting around Saturn

The Cassini mission is a cooperative project of NASA, ESA (the European Space Agency) and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colorado.

For more information about the Cassini-Huygens mission visit http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov. The Cassini imaging team homepage is at http://ciclops.org and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Images, Text, Credits: Credit: NASA/JPL-Caltech/Space Science Institute/Tony Greicius.

Greetings, Orbiter.ch

Four decades of tracking European spacecraft

ESA & ESOC logos.

18 May 2015

Forty years ago this week, a satellite ground station in Spain became the first to be assigned to what would become ESA. Since then, the network – Estrack – has expanded worldwide and today employs cutting-edge technology to link mission controllers with spacecraft orbiting Earth, voyaging deep in our Solar System or anywhere in between.

On 19 May 1975, a ground station at Villafranca del Castillo, Spain, built for the International Ultraviolet Explorer satellite was assigned to ESRO to support future ESA missions.

Villafranca tracking station 1977

Later that month, ESRO merged with ELDO to form ESA, and the Villafranca station became the kernel of Estrack.

The 15 m-diameter parabolic dish antenna of the Villafranca station has been part of many major ESA missions, including Marecs, Exosat, ISO, Integral and Cluster, and, more recently, XMM and ATV .

It was later joined by similar stations in Sweden, Spain, French Guiana, Belgium and Australia, all optimised for tracking satellites near Earth. The original Villafranca location has since become ESAC, the European Space Astronomy Centre, ESA’s major establishment in Spain.

Worldwide network

Estrack has evolved with the expanding needs of ESA’s science, Earth and exploration missions. Today, there are 10 stations in seven countries, all centrally managed from ESOC, the European Space Operations Centre, Darmstadt, Germany.

ESTRACK control Room at ESOC

The essential task of Estrack stations is to communicate with spacecraft, transmitting commands and receiving scientific data and spacecraft status information. They also gather ‘radiometric’ information to help mission controllers know the location, trajectory and speed of their spacecraft.

Tracking is provided through all phases of a mission, from ‘LEOP’ – the critical Launch and Early Orbit Phase – through to routine operations and ultimately deorbiting and safe disposal. Estrack also tracks rockets flying from Kourou in French Guiana.

In a typical year, stations provide over 45 000 hours of tracking to more than 20 missions, with an enviable service availability rate above 99%.

Building Europe's deep-space capability

In the 2000s, the first of three 35 m-diameter Deep Space Antennas was built in New Norcia, Australia, followed by stations at Cebreros, Spain, and Malargüe, Argentina. These feature some of the world’s best tracking station technology and enable communications with spacecraft exploring planets, watching the Sun or located at the scientifically crucial Sun–Earth Lagrange points.

Malargüe under construction 2011

In January 2014, Estrack received signals and sent commands to Rosetta, then travelling some 800 million km from Earth.

Estrack routinely communicates with missions voyaging across our Solar System, including not only ESA missions like Rosetta, Venus Express and Mars Express but also partner missions like Japan's Hayabusa-2, heading towards an asteroid landing in 2018.

Global cooperation

The capabilities of the network enable Estrack stations to support missions of other space agencies in the US, France, Germany, Japan, Russia and China.

ESTRACK network and cooperatives networks map

In future, the three deep-space stations will be upgraded to use ultra-high radio frequencies, necessary to boost scientific data delivery from missions like BepiColombo and Juice. Of course, the network will continue to work with Earth observation missions and perform critical LEOP and launcher tracking.

Happy birthday, Estrack! And congratulations on four decades of linking people with spacecraft travelling to the frontiers of human knowledge.

Related links:

International Ultraviolet Explorer satellite: http://www.esa.int/Our_Activities/Space_Science/IUE_overview

Estrack deep space brochure (PDF): http://download.esa.int/esoc/esa-estrack-dsa-brochure2012-en.pdf

Estrack network profile: http://www.esa.int/ESA_Multimedia/Videos/2012/12/ESTRACK_-_ESA_tracking_station_network_profile

Tracking spacecraft deep across the void: http://www.esa.int/ESA_Multimedia/Videos/2013/09/Tracking_spacecraft_deep_across_the_void

ESTRACK stations:

New Norcia - DSA 1: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/New_Norcia_-_DSA_1

Cebreros - DSA 2: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Cebreros_-_DSA_2

Malargüe - DSA 3: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Malarguee_-_DSA_3

Kiruna station: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Kiruna_station

Kourou station: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Kourou_station

Maspalomas station: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Maspalomas_station

Perth station: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Perth_station

Redu station: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Redu_station

Santa Maria station: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Santa_Maria_station

Villafranca station: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Villafranca_station

Estrack Control Centre: http://www.esa.int/Our_Activities/Operations/European_Space_Tracking_Estrack_network/Estrack_Control_Centre

Cebreros webcam: http://www.esa.int/Our_Activities/Operations/ESTRACK_Cebreros_webcam

Malargüe webcam: http://www.esa.int/Our_Activities/Operations/ESTRACK_Malarguee_webcam

Images, Text, Credits: European Space Agency (ESA)/Air & Space.

Best regards, Orbiter.ch

The ISS reboost on the right orbit

ROSCOSMOS - Russian Vehicles patch.

May 18, 2015

The Russian space agency announced Monday that the Progress spacecraft docked to the International Space Station (ISS) had succeeded as planned to start its engines.

The operation began just after 3:30 pm Moscow time (2:30 Swiss time) and ended about 30 minutes later, Roscosmos said. Docked to the Russian Zvezda module, cargo ship Progress M-26M has managed to correct the orbit of the ISS. He placed at the desired altitude for the return to Earth of three members of the crew of the station early June.

ISS reboost by Progress M

A first attempt failed in the night from Friday to Saturday, causing a crisis in the Russian space industry that is a series of embarrassing setbacks. Russian flight operators had not managed to start the engines of spacecraft and had to cancel the mission.

A few hours after this failure, Russia had lost a Mexican telecommunications satellite after the failed launch of Proton-M carrier rocket from the Baikonur cosmodrome Russian, Kazakhstan.

According to Roscosmos, the engines of the third stage of the rocket responsible for putting the satellite in orbit had malfunctioned. They had caused the fall of the 3rd and 4th floors of the rocket and the satellite, which had fallen to Earth and had disintegrated in the atmosphere.

Heads threatened

A commission of inquiry was created immediately after the loss of this rocket, Russian Prime Minister Dmitry Medvedev demanding answers from the head of the space agency, Igor Komarov, and names of officials, suggesting that the heads could fall. Last year, Russia had already fired the director of Roscosmos after a series of failures.

Progress M 3D Cutaway

These setbacks came less than a month after the loss of control of an unmanned Progress cargo spacecraft supposedly supply the ISS. He had lost contact with Earth shortly after takeoff on April 28 and had disintegrated in the atmosphere on May 8th.

The accident forced him to postpone to June Roscosmos return to Earth from the ISS expedition 43, composed of Russian Anton Chkaplerov, the American Terry Virts and Samantha Italian Cristoforetti.

ROSCOSMOS Press Release: http://www.federalspace.ru/21493/

For more information about the International Space Station (ISS), visit: http://www.nasa.gov/mission_pages/station/main/index.html

Images, Text, Credits: ATS/Roscosmos/NASA/G. De Chiara, Mars Center/Orbiter.ch Aerospace.

Greetings, Orbiter.ch

Rosetta - Closeup: Hathor, from Seth

ESA - Rosetta Mission patch.

May 16, 2015

Today’s post delves back in time to October last year, when Rosetta was orbiting the comet at a distance of just 10 km.

Hathor and Seth – NavCam

Image above: Single frame, processed NAVCAM image of Comet 67P/C-G taken on 23 October from a distance of 9.8 km to the comet centre. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0.

This single frame NAVCAM image was captured on 23 October, when the distance to the centre of the comet was 9.76 km. The average image scale is therefore about 83 cm/pixel and the image measures 850 m across (note that because of the viewing geometry, foreground regions are up to 2 km closer to the viewer, and therefore have an approximate scale of 67 cm/pixel). For reference, an image in a similar orientation was captured on 26 November.

The scene highlights the hauntingly beautiful backlit cliffs of Hathor, the summit just catching the sunlight at top left. The image has been lightly processed to better bring out the details of this region, and also reveals the diffuse glow of the comet’s activity. Indeed, subtly brighter patches can be traced against the darker background, in particular at the right of the frame at the transition from the foreground terrain to Hathor in the background.

If you were standing at the base of Hathor in the Hapi region – out of view in this image – these near-vertical cliffs would tower some 900m above you. As can be seen here, Hathor is characterised by sets of linear features that extend for much of the height of the cliff. In places, lineaments and terraces also cut across roughly perpendicular to them. As described by Thomas et al in an OSIRIS science paper earlier this year, Hathor may be an eroded surface and as such is showing us the internal structure of the comet’s head.

Comet 67P/Churyumov-Gerasimenko regional maps. Image Credit: ESA

In the foreground, contrasting terrains within the Seth region on the comet’s large lobe are observed. While the left-hand portion exhibits a smooth surface, the right-hand portion shows outcrops of more rugged terrain and numerous boulders. The exposed surfaces also display linear structures in various orientations.

The portion of Seth seen here is at an intersection of several regions: at the far right of the frame lies the boundary between Seth and Anubis, while just out of view beyond the bottom of the frame are Ash and Atum.

The original 1024 x 1024 pixel image is provided below:

(Click on the image for enlarge)

Image above: Single frame, processed NAVCAM image of Comet 67P/C-G taken on 23 October from a distance of 9.8 km to the comet centre. Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0.

Today's image is one of many that will be included in the NAVCAM data release scheduled for the end of this month. This will see the release of the entire collection of images taken from the 10 km orbit last year, along with images taken around the events of comet landing. You can browse all NAVCAM images released so far in the Archive Image Browser: http://imagearchives.esac.esa.int/

Related links:

OSIRIS science paper: http://www.sciencemag.org/content/347/6220/aaa0440.full

CometWatch 26 November: http://blogs.esa.int/rosetta/2014/11/28/cometwatch-26-november/

For more information about Rosetta mission, visit: http://www.esa.int/Our_Activities/Space_Science/Rosetta

Images (mentioned), Text, Credit: ESA.

Best regards, Orbiter.ch