samedi 15 novembre 2014

Pioneering Philae completes main mission before hibernation












ESA - Rosetta Mission patch.

15 November 2014

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.

Philae's first touchdown seen by Rosetta's NavCam

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.

In addition, the lander’s body was lifted by about 4 cm and rotated about 35° in an attempt to receive more solar energy. But as the last science data fed back to Earth, Philae’s power rapidly depleted.

“It has been a huge success, the whole team is delighted,” said Stephan Ulamec, lander manager at the DLR German Aerospace Agency, who monitored Philae’s progress from ESA’s Space Operations Centre in Darmstadt, Germany, this week.

First comet panoramic

“Despite the unplanned series of three touchdowns, all of our instruments could be operated and now it’s time to see what we’ve got.”

Against the odds – with no downwards thruster and with the automated harpoon system not having worked – Philae bounced twice after its first touchdown on the comet, coming to rest in the shadow of a cliff on Wednesday 12 November at 17:32 GMT (comet time – it takes over 28 minutes for the signal to reach Earth, via Rosetta).

The search for Philae’s final landing site continues, with high-resolution images from the orbiter being closely scrutinised. Meanwhile, the lander has returned unprecedented images of its surroundings.

While descent images show that the surface of the comet is covered by dust and debris ranging from millimetre to metre sizes, panoramic images show layered walls of harder-looking material.  The science teams are now studying their data to see if they have sampled any of this material with Philae’s drill.

Philae’s instruments

“We still hope that at a later stage of the mission, perhaps when we are nearer to the Sun, that we might have enough solar illumination to wake up the lander and re-establish communication, ” added Stephan.

From now on, no contact will be possible unless sufficient sunlight falls on the solar panels to generate enough power to wake it up. The possibility that this may happen later in the mission was boosted when mission controllers sent commands to rotate the lander’s main body with its fixed solar panels. This should have exposed more panel area to sunlight.

The next possible communication slot begins on 15 November at about 10:00 GMT / 11:00 CET. The orbiter will listen for a signal, and will continue doing so each time its orbit brings it into line-of-sight visibility with Philae. However, given the low recharge current coming from the solar panels at this time, it is unlikely that contact will be re-established with the lander in the near future.

Meanwhile, the Rosetta orbiter has been moving back into a 30 km orbit around the comet.

It will return to a 20 km orbit on 6 December and continue its mission to study the body in great detail as the comet becomes more active, en route to its closest encounter with the Sun on 13 August next year. 

Over the coming months, Rosetta will start to fly in more distant ‘unbound’ orbits, while performing a series of daring flybys past the comet, some within just 8 km of its centre.

Rosetta’s trajectory after 12 November

Data collected by the orbiter will allow scientists to watch the short- and long-term changes that take place on the comet, helping to answer some of the biggest and most important questions regarding the history of our Solar System. How did it form and evolve?  How do comets work? What role did comets play in the evolution of the planets, of water on the Earth, and perhaps even of life on our home world.

“The data collected by Philae and Rosetta is set to make this mission a game-changer in cometary science,” says Matt Taylor, ESA’s Rosetta project scientist.

Fred Jansen, ESA’s Rosetta mission manager, says, “At the end of this amazing rollercoaster week, we look back on a successful first-ever soft-landing on a comet. This was a truly historic moment for ESA and its partners. We now look forward to many more months of exciting Rosetta science and possibly a return of Philae from hibernation at some point in time.”

More about Rosetta:

Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI.

Related articles:

Touchdown! Rosetta’s Philae probe lands on comet: http://orbiterchspacenews.blogspot.ch/2014/11/touchdown-rosettas-philae-probe-lands.html

First images from the surface of the comet 67P/Churyumov–Gerasimenko: http://orbiterchspacenews.blogspot.ch/2014/11/first-images-from-surface-of-comet.html

Three touchdowns for Rosetta’s lander: http://orbiterchspacenews.blogspot.ch/2014/11/three-touchdowns-for-rosettas-lander.html

Related links:

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

Rosetta  Operations: http://www.esa.int/Our_Activities/Operations

Rosetta Blog: http://blogs.esa.int/rosetta/ 

Images, Text, Credits: ESA/Rosetta/NAVCAM – CC BY-SA IGO 3.0/Philae/CIVA/ATG medialab.

Best regards, Orbiter.ch

vendredi 14 novembre 2014

On the work of the spacecraft Electro-L №1












ROSCOSMOS logo.

11/14/2014

Hydrometeorological geostationary space complex Electro-L was launched on January 20, 2011 to complete operational multispectral shooting clouds, land surface and the ocean in the entire observable Earth disc.

The satellite is in a geostationary orbit at distances ~ 760 E and currently continues to be used for the intended purpose with some restrictions. The orientation of the spacecraft is performed on engines stabilization. Even after the introduction of restrictions on the purpose of the spacecraft camera provides data observing all the visible disk of the Earth.


Image above: Picture taken with the spacecraft Electro-L № 1. November 6, 2014.

Multispectral Camera spacecraft Electro-L provides work for a given program with the ability to capture images of the Earth in 10 bands visible and thermal infrared spectral regions.

Installed on board equipment provides data on geophysical conditions in near-Earth space, perform telecommunications functions for the dissemination of hydrometeorological and heliogeophysical data and relay information from the meteorological data collection platforms and ground units COSPAS-SARSAT relay service and other information.

Electro-L № 1 spacecraft

The spacecraft includes a channel relay signals from distress beacons (EPIRBs) COSPAS-SARSAT channel relaying weather information from data collection platforms (DCPs) to receive data from the station platforms (SPDP) and Channel information transfer from heliogeophysical equipment complex. Shooting clouds and the underlying earth's surface by means of multispectral scanner hydrometeorological MSU-GS development of JSC Russian Space Systems.

ROSCOSMOS Press Release: http://www.federalspace.ru/21113/

Images, Text, Credits: Press Service of the Russian Space Agency/ROSCOSMOS/Gunter's Space Page/Translation: Orbiter.ch Aerospace.

Cheers, Orbiter.ch

New Map Shows Frequency of Small Asteroid Impacts











Asteroid Watch logo.

November 14, 2014

New Map Shows Frequency of Small Asteroid Impacts, Provides Clues on Larger Asteroid Population


Image above: This diagram maps the data gathered from 1994-2013 on small asteroids impacting Earth's atmosphere to create very bright meteors, technically called "bolides" and commonly referred to as "fireballs".  Sizes of red dots (daytime impacts) and blue dots (nighttime impacts) are proportional to the optical radiated energy of impacts measured in billions of Joules (GJ) of energy, and show the location of impacts from objects about 1 meter (3 feet) to almost 20 meters (60 feet) in size. Image Credit: Planetary Science.

A map released today by NASA's Near Earth Object (NEO) Program reveals that small asteroids frequently enter and disintegrate in the Earth's atmosphere with random distribution around the globe. Released to the scientific community, the map visualizes data gathered by U.S. government sensors from 1994 to 2013. The data indicate that Earth's atmosphere was impacted by small asteroids, resulting in a bolide (or fireball), on 556 separate occasions in a 20-year period. Almost all asteroids of this size disintegrate in the atmosphere and are usually harmless. The notable exception was the Chelyabinsk event which was the largest asteroid to hit Earth in this period. The new data could help scientists better refine estimates of the distribution of the sizes of NEOs including larger ones that could pose a danger to Earth.

Finding and characterizing hazardous asteroids to protect our home planet is a high priority for NASA. It is one of the reasons NASA has increased by a factor of 10 investments in asteroid detection, characterization and mitigation activities over the last five years. In addition, NASA has aggressively developed strategies and plans with its partners in the U.S. and abroad to detect, track and characterize NEOs. These activities also will help identify NEOs that might pose a risk of Earth impact, and further help inform developing options for planetary defense.

The public can help participate in the hunt for potentially hazardous Near Earth Objects through the Asteroid Grand Challenge, which aims to create a plan to find all asteroid threats to human populations and know what to do about them. NASA is also pursuing an Asteroid Redirect Mission (ARM) which will identify, redirect and send astronauts to explore an asteroid. Among its many exploration goals, the mission could demonstrate basic planetary defense techniques for asteroid deflection.

For more information about the map and data, go to: http://neo.jpl.nasa.gov

For details about ARM, and the Asteroid Grand Challenge, visit: http://www.nasa.gov/asteroidinitiative

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Near-Earth Object Program Office for NASA's Science Mission Directorate in Washington. JPL is a division of the California Institute of Technology in Pasadena.

Image (mentioned), Text, Credits: NASA/Dwayne Brown/JPL/DC Agle.

Greetings, Orbiter.ch

Three touchdowns for Rosetta’s lander












ESA - Rosetta Mission patch.

14 November 2014

Searching for Philae

Image above: This five-image montage of OSIRIS narrow-angle images is being used to try to identify the final touchdown point of Rosetta’s lander Philae. The images were taken around the time of landing on 12 November when Rosetta was about 18 km from the centre of Comet 67P/Churyumov-Gerasimenko (about 16 km from the surface).

After achieving touchdown on a comet for the first time in history, scientists and engineers are busy analysing this new world and the nature of the landing.

Touchdown was confirmed at ESA’s Space Operations Centre in Darmstadt, Germany at 16:03 GMT/17:03 CET on 12 November.

Since then, scientists, flight dynamics specialists and engineers from ESA, the Lander Control Centre in Cologne, Germany, and the Philae Science, Operations and Navigation Centre in Toulouse, France have been studying the first data returned from the lander.

These revealed the astonishing conclusion that the lander did not just touch down on Comet 67P/Churyumov–Gerasimenko once, but three times.

First touchdown

Image above: His image from Rosetta’s OSIRIS narrow-angle camera is marked to show the location of the first touchdown point of the Philae lander. It is thought that Philae bounced twice before settling on the surface of Comet 67P/Churyumov-Gerasimenko.

The harpoons did not fire and Philae appeared to be rotating after the first touchdown, which indicated that it had lifted from the surface again.

Stephan Ulamec, Philae manager at the DLR German Aerospace Center, reported that it touched the surface at 15:34, 17:25 and 17:32 GMT (comet time – it takes over 28 minutes for the signal to reach Earth, via Rosetta). The information was provided by several of the scientific instruments, including the ROMAP magnetic field analyser, the MUPUS thermal mapper, and the sensors in the landing gear that were pushed in on the first impact.

The first touchdown was inside the predicted landing ellipse, confirmed using the lander’s downwards-looking ROLIS descent camera in combination with the orbiter’s OSIRIS images to match features.

But then the lander lifted from the surface again – for 1 hour 50 minutes. During that time, it travelled about 1 km at a speed of 38 cm/s. It then made a smaller second hop, travelling at about 3 cm/s, and landing in its final resting place seven minutes later.

First comet panoramic

Image above: Rosetta’s lander Philae has returned the first panoramic image from the surface of a comet. The view, unprocessed, as it has been captured by the CIVA-P imaging system, shows a 360º view around the point of final touchdown. The three feet of Philae’s landing gear can be seen in some of the frames.

The touchdown signal generated on first touchdown induced the instruments to ‘think’ that Philae had landed, triggering the next sequence of experiments. Now those data are being used to interpret the bounces.

Preliminary data from the CONSERT experiment suggest that Philae could have travelled closer to the large depression known as Site B, perhaps sitting on its rim. High-resolution orbiter images, some of which are still stored on Rosetta, have yet to confirm the location.

The lander remains unanchored to the surface at an as yet undetermined orientation. The science instruments are running and are delivering images and data, helping the team to learn more about the final landing site.

Philae’s instruments description

The descent camera revealed that the surface is covered by dust and debris ranging from millimetre to metre sizes. Meanwhile, Philae’s CIVA camera returned a panoramic image that on first impressions suggests the lander is close to a rocky wall, and perhaps has one of its three feet in open space.

After discussions as to whether to activate those science instruments that may cause the position of Philae to shift, MUPUS and APXS have both been deployed.

The primary battery enabling the core science goals of the lander may run out some time in the next 24 hours. As for the secondary battery, charged by solar panels on Philae, with only 1.5 hours of sunlight available to the lander each day, there is an impact on the energy budget to conduct science for a longer period of time. The original landing site offered nearly seven hours of illumination per 12.4 hour comet day.

Related links:

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

Rosetta  Operations: http://www.esa.int/Our_Activities/Operations

Rosetta Blog: http://blogs.esa.int/rosetta/

Images, Text, Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/Rosetta/Philae/CIVA.

Best regards, Orbiter.ch

jeudi 13 novembre 2014

How standard is the Higgs boson discovered in 2012?












CERN - European Organization for Nuclear Research logo.

November 13, 2014

The highlight of the first run of the Large Hadron Collider (LHC) was undoubtedly the discovery by the ATLAS and CMS Collaborations of a new elementary particle of a type never seen before. All the properties of this particle measured so far are consistent with those predicted for the Higgs boson of the Standard Model. It was predicted to have zero spin (angular momentum), and every alternative option tested has by now been ruled out with a high degree of confidence. It was predicted to couple with other particles proportionally to their masses, and this is strongly supported by the data. This is why the committee that awarded the 2013 Nobel Physics Prize to Francois Englert and Peter Higgs stated “Beyond any reasonable doubt, it is a Higgs boson.”


Image above: An artist’s approximation of a collision of two protons that produce a Higgs boson. Image Credit: CERN.

Physicists are now asking themselves follow-up questions. Is there any difference between its properties and those predicted in the Standard Model? Is it the only Higgs boson, or are there others? Many of its couplings to other particles have been measured, but what about its coupling to the heaviest known particle, the top quark? Or its couplings to lighter particles like the muon? What gives its mass to this Higgs boson? Is it truly an elementary particle, or is it made of some smaller constituents? Is it a portal to some new physics beyond the Standard Model, such as dark matter?

The next run of the LHC, starting in the spring of 2015, will set about answering some of these questions. For example, its higher energy will enable the LHC experiments to probe more deeply for deviations from the Standard Model predictions, and to search for heavier Higgs bosons. It will be possible to measure directly this Higgs boson's coupling to the top quark, and to box in its possible coupling to the muon. These measurements may reveal some substructure inside this Higgs boson, or provide some other evidence for physics beyond the Standard Model. Time will tell!

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 20 Member States.

Related links:

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

ATLAS: http://home.web.cern.ch/about/experiments/atlas

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

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

The basics of the Higgs boson: http://home.web.cern.ch/about/updates/2013/05/basics-higgs-boson

The origins of the Brout-Englert-Higgs mechanism: http://home.web.cern.ch/topics/higgs-boson/origins-brout-englert-higgs-mechanism

Image, Text, Credits: CERN/John Ellis.

Cheers, Orbiter.ch

NASA X-ray Telescopes Find Black Hole May Be a Neutrino Factory

 











NASA - Chandra X-ray Observatory patch / NASA - Swift Mission patch / NASA -  NuStar Mission patch.

November 13, 2014

Image Credit: NASA/CXC/Univ. of Wisconsin/Y.Bai. et al.

The giant black hole at the center of the Milky Way may be producing mysterious particles called neutrinos. If confirmed, this would be the first time that scientists have traced neutrinos back to a black hole.

The evidence for this came from three NASA satellites that observe in X-ray light: the Chandra X-ray Observatory, the Swift gamma-ray mission, and the Nuclear Spectroscopic Telescope Array (NuSTAR).

Neutrinos are tiny particles that carry no charge and interact very weakly with electrons and protons. Unlike light or charged particles, neutrinos can emerge from deep within their cosmic sources and travel across the universe without being absorbed by intervening matter or, in the case of charged particles, deflected by magnetic fields.

The Earth is constantly bombarded with neutrinos from the sun. However, neutrinos from beyond the solar system can be millions or billions of times more energetic. Scientists have long been searching for the origin of ultra-high energy and very high-energy neutrinos.

“Figuring out where high-energy neutrinos come from is one of the biggest problems in astrophysics today,” said Yang Bai of the University of Wisconsin in Madison, who co-authored a study about these results published in Physical Review D. “We now have the first evidence that an astronomical source – the Milky Way’s supermassive black hole – may be producing these very energetic neutrinos.”

Because neutrinos pass through material very easily, it is extremely difficult to build detectors that reveal exactly where the neutrino came from. The IceCube Neutrino Observatory, located under the South Pole, has detected 36 high-energy neutrinos since the facility became operational in 2010.

By pairing IceCube’s capabilities with the data from the three X-ray telescopes, scientists were able to look for violent events in space that corresponded with the arrival of a high-energy neutrino here on Earth.

Artist's view of Chandra X-ray Observatory. Image Credits: NASA/CXC

“We checked to see what happened after Chandra witnessed the biggest outburst ever detected from Sagittarius A*, the Milky Way’s supermassive black hole,” said co-author Andrea Peterson, also of the University of Wisconsin. “And less than three hours later, there was a neutrino detection at IceCube.”

In addition, several neutrino detections appeared within a few days of flares from the supermassive black hole that were observed with Swift and NuSTAR.

“It would be a very big deal if we find out that Sagittarius A* produces neutrinos,” said co-author Amy Barger of the University of Wisconsin. “It’s a very promising lead for scientists to follow.”

Artist's view of Nuclear Spectroscopic Telescope Array (NuSTAR). Image Credit: NASA

Scientists think that the highest energy neutrinos were created in the most powerful events in the Universe like galaxy mergers, material falling onto supermassive black holes, and the winds around dense rotating stars called pulsars.

The team of researchers is still trying to develop a case for how Sagittarius A* might produce neutrinos. One idea is that it could happen when particles around the black hole are accelerated by a shock wave, like a sonic boom, that produces charged particles that decay to neutrinos.

Artist's view of Swift gamma-ray spacecraft. Image Credit: NASA

This latest result may also contribute to the understanding of another major puzzle in astrophysics: the source of high-energy cosmic rays. Since the charged particles that make up cosmic rays are deflected by magnetic fields in our Galaxy, scientists have been unable to pinpoint their origin. The charged particles accelerated by a shock wave near Sgr A* may be a significant source of very energetic cosmic rays.

The paper describing these results is available online (http://arxiv.org/abs/1407.2243). NASA's Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra's science and flight operations.

For more information about Chandra X-ray Observatory, visit: http://www.nasa.gov/mission_pages/chandra/main/

For more information about Swift gamma-ray mission, visit: http://swift.gsfc.nasa.gov/ and http://www.nasa.gov/mission_pages/swift/main/

For more information about Nuclear Spectroscopic Telescope Array (NuSTAR), visit: http://www.nasa.gov/mission_pages/nustar/main/

Images (mentioned), Text, Credits: NASA Marshall Space Flight Center/Janet Anderson/Chandra X-ray Center/Megan Watzke.

Greetings, Orbiter.ch

First images from the surface of the comet 67P/Churyumov–Gerasimenko












ESA - Rosetta Mission patch.

November 13, 2014

Comet from 40 meters

Image above: This image was taken by Philae's down-looking descent ROLIS imager when it was about 40 m above the surface of Comet 67P/Churyumov-Gerasimenko. Image Credits: ESA/Rosetta/Philae/ROLIS/DLR.

It shows that the surface of the comet is covered by dust and debris ranging from mm to metre sizes.

The large block in the top right corner is 5 m in size. In the same corner the structure of the Philae landing gear is visible. 

The aim of the ROLIS experiment is to study the texture and microstructure of the comet's surface. ROLIS (ROsetta Lander Imaging System) has been developed by the DLR Institute of Planetary Research, Berlin. 

Welcome to a comet

Image above: Rosetta’s lander Philae is safely on the surface of Comet 67P/Churyumov-Gerasimenko, as these first two CIVA images confirm. One of the lander’s three feet can be seen in the foreground. The image is a two-image mosaic. The full panoramic from CIVA will be delivered in this afternoon’s press briefing at 13:00 GMT/14:00 CET. Image Credits: ESA/Rosetta/Philae/CIVA.


Image above: ESA scientists show the approximate location of the Philae lander on the Comet 67P/Churyumov-Gerasimenko comet after a bounce during landing on Nov. 13. Ulamec showed the approximate location on the comet (in blue) where Philae is believed to be. The initial landing area is illustrated in red. Image Credit: ESA TV.

The Philae lander would have bounced three times on the comet, its harpoons do not work properly. In addition, it seems that Philae is placed on a steep slope. This problem fixing the floor of the comet with harpoons could complicated drilling for soil samples.

It was decided to abandon the drill, too risky, the Philae lander may be propelled into space, given its delicate position balanced on two of the three legs. A temperature sensor will be deployed tonight.

Despite all of that, ESA scientists say they the lander is "working very well."

The first panoramic ‘postcard’ from the surface of a comet returned by Rosetta’s lander Philae

First comet panoramic

Image above:  Rosetta’s lander Philae has returned the first panoramic image from the surface of a comet. The view, unprocessed, as it has been captured by the CIVA-P imaging system, shows a 360º view around the point of final touchdown. The three feet of Philae’s landing gear can be seen in some of the frames.

Confirmation of Philae’s touchdown on the surface of Comet 67P/Churyumov–Gerasimenko arrived on Earth at 16:03 GMT/17:03 CET on 12 November. Image Credits: ESA/Rosetta/Philae/CIVA.

Comet panoramic – lander orientation

Image above:  Rosetta’s lander Philae has returned the first panoramic image from the surface of a comet. The view, unprocessed, as it has been captured by the CIVA-P imaging system, shows a 360º view around the point of final touchdown. The three feet of Philae’s landing gear can be seen in some of the frames.

Superimposed on top of the image is a sketch of the Philae lander in the configuration the lander team currently believe it is in. 

Confirmation of Philae’s touchdown on the surface of Comet 67P/Churyumov–Gerasimenko arrived on Earth at 16:03 GMT/17:03 CET on 12 November. Image Credits: ESA/Rosetta/Philae/CIVA.

More about Rosetta:

Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta is the first mission in history to rendezvous with a comet. It is escorting the comet as they orbit the Sun together, and has deployed a lander to its surface.Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System.

Related links:

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

Rosetta  Operations: http://www.esa.int/Our_Activities/Operations

Rosetta Blog: http://blogs.esa.int/rosetta/

Images (mentioned), Text, Credit: ESA / Orbiter.ch Aerospace.

Greetings, Orbiter.ch

mercredi 12 novembre 2014

Touchdown! Rosetta’s Philae probe lands on comet












ESA - Rosetta Mission patch.

12 November 2014

Farewell Philae - narrow-angle view

ESA’s Rosetta mission has soft-landed its Philae probe on a comet, the first time in history that such an extraordinary feat has been achieved.

After a tense wait during the seven-hour descent to the surface of Comet 67P/Churyumov–Gerasimenko, the signal confirming the successful touchdown arrived on Earth at 16:03 GMT (17:03 CET).

The confirmation was relayed via the Rosetta orbiter to Earth and picked up simultaneously by ESA’s ground station in Malargüe, Argentina and NASA’s station in Madrid, Spain. The signal was immediately confirmed at ESA’s Space Operations Centre, ESOC, in Darmstadt, and DLR’s Lander Control Centre in Cologne, both in Germany.

The first data from the lander’s instruments were transmitted to the Philae Science, Operations and Navigation Centre at France’s CNES space agency in Toulouse.

“Our ambitious Rosetta mission has secured a place in the history books: not only is it the first to rendezvous with and orbit a comet, but it is now also the first to deliver a lander to a comet’s surface,” noted Jean-Jacques Dordain, ESA’s Director General.

Philae’s parting image of Rosetta, taken shortly after separation

“With Rosetta we are opening a door to the origin of planet Earth and fostering a better understanding of our future. ESA and its Rosetta mission partners have achieved something extraordinary today.”

“After more than 10 years travelling through space, we’re now making the best ever scientific analysis of one of the oldest remnants of our Solar System,” said Alvaro Giménez, ESA’s Director of Science and Robotic Exploration.

“Decades of preparation have paved the way for today’s success, ensuring that Rosetta continues to be a game-changer in cometary science and space exploration.”

“We are extremely relieved to be safely on the surface of the comet, especially given the extra challenges that we faced with the health of the lander,” said Stephan Ulamec, Philae Lander Manager at the DLR German Aerospace Center.

Philae touchdown

“In the next hours we’ll learn exactly where and how we’ve landed, and we’ll start getting as much science as we can from the surface of this fascinating world.”

Rosetta was launched on 2 March 2004 and travelled 6.4 billion kilometres through the Solar System before arriving at the comet on 6 August 2014.

“Rosetta’s journey has been a continuous operational challenge, requiring an innovative approach, precision and long experience,” said Thomas Reiter, ESA Director of Human Spaceflight and Operations.

“This success is testimony to the outstanding teamwork and the unique knowhow in operating spacecraft acquired at the European Space Agency over the decades.” 

The landing site, named Agilkia and located on the head of the bizarre double-lobed object, was chosen just six weeks after arrival based on images and data collected at distances of 30–100 km from the comet. Those first images soon revealed the comet as a world littered with boulders, towering cliffs and daunting precipices and pits, with jets of gas and dust streaming from the surface.

Following a period spent at 10 km to allow further close-up study of the chosen landing site, Rosetta moved onto a more distant trajectory to prepare for Philae’s deployment.

Five critical go/no-go decisions were made last night and early this morning, confirming different stages of readiness ahead of separation, along with a final preseparation manoeuvre by the orbiter.

Philae’s instruments

Deployment was confirmed at 09:03 GMT (10:03 CET) at a distance of 22.5km from the centre of the comet. During the seven-hour descent, which was made without propulsion or guidance, Philae took images and recorded information about the comet’s environment.

“One of the greatest uncertainties associated with the delivery of the lander was the position of Rosetta at the time of deployment, which was influenced by the activity of the comet at that specific moment, and which in turn could also have affected the lander’s descent trajectory,” said Sylvain Lodiot, ESA Rosetta Spacecraft Operations Manager.

“Furthermore, we’re performing these operations in an environment that we’ve only just started learning about, 510 million kilometres from Earth.”

Touchdown was planned to take place at a speed of around 1 m/s, with the three-legged landing gear absorbing the impact to prevent rebound, and an ice screw in each foot driving into the surface.

But during the final health checks of the lander before separation, a problem was detected with the small thruster on top that was designed to counteract the recoil of the harpoons to push the lander down onto the surface. The conditions of landing – including whether or not the thruster performed – along with the exact location of Philae on the comet are being analysed.

The first images from the surface are being downlinked to Earth and should be available within a few hours of touchdown.

video
 Rosetta’s deployment of Philae to land on Comet 67P/Churyumov–Gerasimenko
 
Over the next 2.5 days, the lander will conduct its primary science mission, assuming that its main battery remains in good health. An extended science phase using the rechargeable secondary battery may be possible, assuming Sun illumination conditions allow and dust settling on the solar panels does not prevent it. This extended phase could last until March 2015, after which conditions inside the lander are expected to be too hot for it to continue operating.

Science highlights from the primary phase will include a full panoramic view of the landing site, including a section in 3D, high-resolution images of the surface immediately underneath the lander, on-the-spot analysis of the composition of the comet’s surface materials, and a drill that will take samples from a depth of 23 cm and feed them to an onboard laboratory for analysis.

The lander will also measure the electrical and mechanical characteristics of the surface. In addition, low-frequency radio signals will be beamed between Philae and the orbiter through the nucleus to probe the internal structure.

The detailed surface measurements that Philae makes at its landing site will complement and calibrate the extensive remote observations made by the orbiter covering the whole comet.

“Rosetta is trying to answer the very big questions about the history of our Solar System. What were the conditions like at its infancy and how did it evolve? What role did comets play in this evolution? How do comets work?” said Matt Taylor, ESA Rosetta project scientist.

“Today’s successful landing is undoubtedly the cherry on the icing of a 4 km-wide cake, but we’re also looking further ahead and onto the next stage of this ground-breaking mission, as we continue to follow the comet around the Sun for 13 months, watching as its activity changes and its surface evolves.”

ROLIS descent image

Image above: The image shows comet 67P/CG acquired by the ROLIS instrument on the Philae lander during descent on Nov 12, 2014 14:38:41 UT from a distance of approximately 3 km from the surface. The landing site is imaged with a resolution of about 3m per pixel.

While Philae begins its close-up study of the comet, Rosetta must manoeuvre from its post-separation path back into an orbit around the comet, eventually returning to a 20 km orbit on 6 December.

Next year, as the comet grows more active, Rosetta will need to step further back and fly unbound ‘orbits’, but dipping in briefly with daring flybys, some of which will bring it within just 8 km of the comet centre.

The comet will reach its closest distance to the Sun on 13 August 2015 at about 185 million km, roughly between the orbits of Earth and Mars. Rosetta will follow it throughout the remainder of 2015, as they head away from the Sun and activity begins to subside.

“It’s been an extremely long and hard journey to reach today’s once-in-a-lifetime event, but it was absolutely worthwhile. We look forward to the continued success of the great scientific endeavour that is the Rosetta mission as it promises to revolutionise our understanding of comets,” said Fred Jansen, ESA Rosetta mission manager.

More about Rosetta:

Rosetta is an ESA mission with contributions from its Member States and NASA. Rosetta’s Philae lander is provided by a consortium led by DLR, MPS, CNES and ASI. Rosetta is the first mission in history to rendezvous with a comet. It is escorting the comet as they orbit the Sun together, and has deployed a lander to its surface.Comets are time capsules containing primitive material left over from the epoch when the Sun and its planets formed. By studying the gas, dust and structure of the nucleus and organic materials associated with the comet, via both remote and in situ observations, the Rosetta mission should become the key to unlocking the history and evolution of our Solar System.

About the European Space Agency:

The European Space Agency (ESA) provides Europe’s gateway to space.

ESA is an intergovernmental organisation, created in 1975, with the mission to shape the development of Europe’s space capability and ensure that investment in space delivers benefits to the citizens of Europe and the world.

ESA has 20 Member States: Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Ireland, Italy, Luxem-bourg, the Netherlands, Norway, Poland, Portugal, Romania, Spain, Sweden, Switzerland and the United Kingdom, of whom 18 are Member States of the EU. Two other Member States of the EU, Hungary and Estonia, are likely soon to become new ESA Member States.

ESA has Cooperation Agreements with six other Member States of the EU. Canada takes part in some ESA programmes under a Cooperation Agreement.

ESA is also working with the EU on implementing the Galileo and Copernicus programmes.

By coordinating the financial and intellectual resources of its members, ESA can undertake programmes and activities far beyond the scope of any single European country.

ESA develops the launchers, spacecraft and ground facilities needed to keep Europe at the forefront of global space activities.

Today, it develops and launches satellites for Earth observation, naviga-tion, telecommunications and astronomy, sends probes to the far reaches of the Solar System and cooperates in the human exploration of space.

Learn more about ESA at http://www.esa.int

Related links:

Rosetta overview: http://www.esa.int/Our_Activities/Space_Science/Rosetta_overview

Rosetta factsheet: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Rosetta_factsheet

Frequently asked questions: http://www.esa.int/Our_Activities/Space_Science/Rosetta/Frequently_asked_questions

Rosetta  Operations: http://www.esa.int/Our_Activities/Operations

Rosetta Blog: http://blogs.esa.int/rosetta/

Images, Video, Text, Credits: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA/ATG medialab/Philae/ROLIS/DLR.

Best regards, Orbiter.ch

mardi 11 novembre 2014

NASA's New Wind Watcher Ready for Weather Forecasters












ISS - International Space Station patch.

November 10, 2014

In an early holiday gift to the world's weather and marine forecasting agencies, ocean-winds data from NASA's newest Earth-observing mission, the International Space Station-Rapid Scatterometer (ISS-RapidScat), are being released two months ahead of schedule.


Image above: ISS-RapidScat data on a North Atlantic extratropical cyclone, as seen by the National Centers for Environmental Prediction Advanced Weather Interactive Processing System used by weather forecasters at the National Oceanic and Atmospheric Administration's Ocean Prediction Center. Image Credit: NASA/JPL-Caltech/NOAA.

RapidScat launched to the International Space Station on Sept. 21 on a two-year mission to boost global monitoring of ocean winds for improved weather forecasting and climate studies. The JPL-developed space-based scatterometer is a remote-sensing instrument that uses radar pulses reflected from the ocean's surface at different angles to calculate surface wind speed and direction. This information will improve weather and marine forecasting and hurricane monitoring.

Working at an accelerated pace, scientists and engineers have successfully cross-calibrated ISS-RapidScat's ocean winds data with data from NASA's QuikScat satellite and validated the data against ground measurements. The team reports the RapidScat data are meeting all planned wind performance requirements and are ready to begin extending the long-term climate data record of ocean-surface winds begun by QuikScat in 1999.

The team includes scientists and engineers from NASA's Jet Propulsion Laboratory, Pasadena, California; the National Oceanic and Atmospheric Administration; Brigham Young University, Provo, Utah; and Remote Sensing Systems, Santa Rosa, California.


Image above: ISS-RapidScat viewed the winds within post-tropical cyclone Nuri as it moved parallel to Japan on Nov. 6, 2014 05:30 UTC. Image Credit: NASA/JPL-Caltech.

"RapidScat is a short mission by NASA standards," said RapidScat Project Scientist Ernesto Rodriguez of JPL. "Its data will be ready to help support U.S. weather forecasting needs during the tail end of the 2014 hurricane season. The dissemination of these data to the international operational weather and marine forecasting communities ensures that RapidScat's benefits will be felt throughout the world."

The agencies that will receive near-real-time RapidScat data include NOAA, the U.S. Navy, the European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT), the Indian Space Research Organisation (ISRO) and the Royal Netherlands Meteorological Institute (KNMI). The data will also be distributed to RapidScat science team members. The spatial sampling – how far apart the samples are-- of RapidScat data is currently 15.5 miles (25 kilometers). A version to be released in the near future will double its spatial resolution – meaning it will shrink the distance between samples by half.

"The initial quality of the RapidScat wind data and the timely availability of products so soon after launch are remarkable," said Paul Chang, ocean vector winds science team lead at NOAA's National Environmental Satellite, Data and Information Service (NESDIS)/Center for Satellite Applications and Research (STAR), Silver Spring, Maryland. "NOAA is looking forward to using RapidScat data to help support marine wind and wave forecasting and warning, and to exploring the unique sampling of the ocean wind fields provided by the space station's orbit."


Image above: The remnants of Nuri brought very high winds and seas to Alaska's Aleutian Islands and the Bering Sea. This ISS-RapidScat image shows the storm as it appeared near 4 p.m. Pacific Time on Nov. 8. The intense storm will push unseasonably cold air into much of the United States this week. Image Credit: NASA/JPL-Caltech.

ISS-RapidScat's berth on the space station's Columbus module puts it in an orbit unique from any other wind-measuring instrument currently in orbit. This vantage point will give scientists the first near-global direct observations of how ocean winds vary over the course of the day due to solar heating. Because it crosses the path of every other scatterometer currently in orbit, ISS-RapidScat will also be able to ensure that all spaceborne scatterometer data sets are accurate and consistent with each other, a process known as cross-calibration.


Animation above: RapidScat on International Space Station. Image Credit: NASA/JPL-Caltech.

ISS-RapidScat is a partnership between JPL and the International Space Station Program Office at NASA's Johnson Space Center, Houston, with support from the Earth Science Division of NASA's Science Mission Directorate, Washington. Other ongoing mission partners include NASA's Marshall Space Flight Center, Huntsville, Alabama; and the European Space Agency.

For more information on ISS-RapidScat, visit: http://winds.jpl.nasa.gov/missions/RapidScat/ and http://www.nasa.gov/rapidscat

For more information on Earth science activities aboard the space station, visit: http://www.nasa.gov/issearthscience

ISS-RapidScat is the third of five NASA Earth science missions scheduled to launch into space within 12 months, the most new Earth-observing mission launches in one year in more than a decade. NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.

For more information about NASA's Earth science activities in 2014, visit: http://www.nasa.gov/earthrightnow

Images (mentioned), Text, Credits: NASA/JPL/Alan Buis.

Cheers, Orbiter.ch

Jupiter's Red Spot is Likely a Sunburn, Not a Blush










NASA - Cassini International logo.

November 11, 2014


Image above: Research suggests effects of sunlight produce the color of Jupiter's Great Red Spot. The feature's clouds are much higher than those elsewhere on the planet, and its vortex nature confines the reddish particles once they form. Image Credit: NASA/JPL-Caltech/ Space Science Institute.

The ruddy color of Jupiter's Great Red Spot is likely a product of simple chemicals being broken apart by sunlight in the planet's upper atmosphere, according to a new analysis of data from NASA's Cassini mission. The results contradict the other leading theory for the origin of the spot's striking color -- that the reddish chemicals come from beneath Jupiter's clouds.

The results are being presented this week by Kevin Baines, a Cassini team scientist based at NASA's Jet Propulsion Laboratory, Pasadena, California, at the American Astronomical Society's Division for Planetary Science Meeting in Tucson, Arizona.

Baines and JPL colleagues Bob Carlson and Tom Momary arrived at their conclusions using a combination of data from Cassini's December 2000 Jupiter flyby and laboratory experiments.

In the lab, the researchers blasted ammonia and acetylene gases -- chemicals known to exist on Jupiter -- with ultraviolet light, to simulate the sun's effects on these materials at the extreme heights of clouds in the Great Red Spot. This produced a reddish material, which the team compared to the Great Red Spot as observed by Cassini's Visible and Infrared Mapping Spectrometer (VIMS). They found that the light-scattering properties of their red concoction nicely matched a model of the Great Red Spot in which the red-colored material is confined to the uppermost reaches of the giant cyclone-like feature.

"Our models suggest most of the Great Red Spot is actually pretty bland in color, beneath the upper cloud layer of reddish material," said Baines. "Under the reddish 'sunburn' the clouds are probably whitish or grayish." A coloring agent confined to the top of the clouds would be inconsistent with the competing theory, which posits that the spot's red color is due to upwelling chemicals formed deep beneath the visible cloud layers, he said. If red material were being transported from below, it should be present at other altitudes as well, which would make the red spot redder still.

Jupiter is composed almost entirely of hydrogen and helium, with just a sprinkling of other elements. Scientists are interested in understanding what combinations of elements are responsible for the hues seen in Jupiter's clouds, as this would provide insights into the giant planet's make-up.

Baines and colleagues initially set out to determine if the Great Red Spot's color might derive from sun-induced breakdown of a more complex molecule, ammonium hydrosulfide, which makes up one of Jupiter's main cloud layers. They quickly found that instead of a red color, the products their experiment produced were a brilliant shade of green. This surprising negative result prompted the researchers to try simple combinations of ammonia with hydrocarbons that are common at Jupiter's high altitudes. Breaking down ammonia and acetylene with ultraviolet light turned out to best fit the data collected by Cassini.


Image above: The shrinking of Jupiter’s Great Red Spot. Image Credit: NASA/ESA/Hubble/Space Science Institute.

The Great Red Spot is a long-lived feature in Jupiter's atmosphere that is as wide as two earths. Jupiter possesses three main cloud layers, which occupy specific altitudes in its skies; from highest to lowest they are: ammonia, ammonium hydrosulfide and water clouds.

As for why the intense red color is seen only in the Great Red Spot and a few much smaller spots on the planet, the researchers think altitude plays a key role. "The Great Red Spot is extremely tall," Baines said. "It reaches much higher altitudes than clouds elsewhere on Jupiter."

The team thinks the spot's great heights both enable and enhance the reddening. Its winds transport ammonia ice particles higher into the atmosphere than usual, where they are exposed to much more of the sun's ultraviolet light. In addition, the vortex nature of the spot confines particles, preventing them from escaping. This causes the redness of the spot's cloud tops to increase beyond what might otherwise be expected.

Other areas of Jupiter display a mixed palette of oranges, browns and even shades of red. Baines says these are places where high, bright clouds are known to be much thinner, allowing views to depths in the atmosphere where more colorful substances exist.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson.

Related article:

The shrinking of Jupiter’s Great Red Spot: http://orbiterchspacenews.blogspot.ch/2014/05/the-shrinking-of-jupiters-great-red-spot.html

More information about Cassini is available at the following sites:

http://www.nasa.gov/cassini and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

http://saturn.jpl.nasa.gov

Images (mentioned), Text, Credits: NASA/JPL/Preston Dyches.

Greetings, Orbiter.ch

Follow the Dust to Find Planets














NASA - Spitzer Space Telescope patch / ESA - Herschel Mission patch.

November 11, 2014

Researchers studying what appears to be a beefed-up version of our solar system have discovered that it is encased in a halo of fine dust. The findings are based on infrared data from NASA's Spitzer Space Telescope and the European Space Agency's Herschel Space Observatory, in which NASA is a partner.

The dusty star system, called HD 95086, is located 295 light-years from Earth in the constellation Carina. It is thought to include two belts of dust, which lie within the newfound outer dust halo. One of these belts is warm and closer to its star, as is the case with our solar system's asteroid belt, while the second belt is cooler and farther out, similar to our own Kuiper belt of icy comets.


Image above: This artist's concept depicts giant planets circling between belts of dust. Scientists think the star system HD 95068 may have a planetary architecture similar to this. While the star system's two dust belts are known, along with one massive planet, more giant planets may lurk unseen. Image credit: NASA/JPL-Caltech.

"By looking at other star systems like these, we can piece together how our own solar system came to be," said Kate Su, an associate astronomer at the University of Arizona, Tucson, and lead author of the paper.

Within our solar system, the planets Jupiter, Saturn, Uranus and Neptune are sandwiched between the two dust belts. Scientists think something similar is happening in the star system HD 95086, only on larger scales. One planet, about five times the mass of Jupiter, is already known to sit right inside HD 95086's cooler belt. Other massive planets may be lurking between the two dust belts, waiting to be discovered.

Studies like this from Spitzer and Herschel point the way for ground-based telescopes to snap pictures of such planets in hiding, a technique referred to as direct imaging. The one planet known to exist in HD 95086 was, in fact, discovered and imaged using this technique in 2013. The images aren't sharp because the planets are so faint and far away, but they reveal new information about the global architecture of a planetary system.

"By knowing where the debris is, plus the properties of the known planet in the system, we can get an idea of what other kinds of planets can be there," said Sarah Morrison, a co-author of the paper and a PhD student at the University of Arizona. She ran computer models to constrain the possibilities of how many planets are likely to inhabit the system. "We know that we should be looking for multiple planets instead of a single giant planet."

To learn what HD 95086 looks like, the astronomers turned to a similar star system called HR 8799. It too has an inner and outer belt of debris surrounded by a large halo of fine dust, and four known planets between the belts -- among the first exoplanets, or planets beyond our solar system, to be directly imaged.


Images above: This diagram illustrates two similar star systems, HD 95086 and HR 8799. Evidence from NASA's Spitzer Space Telescope has pointed to the presence of two dust belts in each system: warm, inner belts similar to our solar system's asteroid belt, and cool, outer belts like our Kuiper belt of icy comets. Image credit: NASA/JPL-Caltech.

Comparing data from the two star systems hints that HD95086, like its cousin HR 8799, is a possible home to multiple planets that have yet to be seen. Ground-based telescopes might be able to take pictures of the family of planets.

Both HD 95086 and HR 8799 are much younger and dustier than our solar system. When planetary systems are young and still forming, collisions between growing planetary bodies, asteroids and comets kick up dust. Some of the dust coagulates into planets, some winds up in the belts, and the rest is either blown out into a halo, or funneled onto the star.

Herschel and Spitzer are ideally suited to study the dust structures in these systems, which glow at the infrared wavelengths the telescopes detect.

The researchers will present the findings at the Division for Planetary Science Meeting of the American Astronomical Society held in Tucson, Arizona from Nov. 8 to 15.

Read more about the research at: http://uanews.org/story/baby-photos-of-a-scaled-up-solar-system

Other coauthors of the paper include Zoltan Balog at the Max-Planck Institute of Astronomy, Heidelberg, Germany, and Renu Malhotra, Paul Smith and George Rieke of the University of Arizona.

NASA's Jet Propulsion Laboratory, Pasadena, California, manages the Spitzer Space Telescope mission for NASA's Science Mission Directorate, Washington. Science operations are conducted at the Spitzer Science Center at the California Institute of Technology in Pasadena. Spacecraft operations are based at Lockheed Martin Space Systems Company, Littleton, Colorado. Data are archived at the Infrared Science Archive housed at the Infrared Processing and Analysis Center at Caltech. Caltech manages JPL for NASA. For more information about Spitzer, visit: http://www.nasa.gov/spitzer

Herschel is a European Space Agency mission, with science instruments provided by consortia of European institutes and with important participation by NASA. While the observatory stopped making science observations in April 2013, after running out of liquid coolant as expected, scientists continue to analyze its data. NASA's Herschel Project Office is based at JPL. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center, supports the U.S. astronomical community. More information is online at: http://www.nasa.gov/herschel and http://www.esa.int/Our_Activities/Space_Science/Herschel

Images (mentioned), Text, Credits: NASA/JPL/Whitney Clavin.

Best regards, Orbiter.ch

lundi 10 novembre 2014

Cassini Sails into New Ocean Adventures on Titan












NASA/ESA - Cassini-Huygens Mission to Saturn & Titan patch.

November 10, 2014

NASA's Cassini mission continues its adventures in extraterrestrial oceanography with new findings about the hydrocarbon seas on Saturn's moon Titan. During a flyby in August, the spacecraft sounded the depths near the mouth of a flooded river valley and observed new, bright features in the seas that might be related to the mysterious feature that researchers dubbed the "magic island."

The findings are being presented this week at the Division for Planetary Sciences Meeting of the American Astronomical Society held in Tucson, Arizona.


Image above: Cassini radar data reveal the depth of a liquid methane/ethane sea on Saturn's moon Titan near the mouth of a large, flooded river valley. Image Credit: NASA/JPL-Caltech/ASI/Cornell.

To the delight of Cassini scientists, two new bright features appeared in Titan’s largest sea, Kraken Mare, during the August 21 flyby. In contrast to a previously reported bright, mystery feature in another of Titan's large seas, Ligeia Mare, the new features in Kraken Mare were observed in both radar data and images from Cassini's Visible and Infrared Mapping Spectrometer (VIMS). Having observations at two different wavelengths provides researchers with important clues to the nature of these enigmatic objects.

The VIMS data suggest the new features might have similarities to places in and around the seas that the Cassini team has interpreted as waves or wet ground. The observations support two of the possible explanations the team thinks are most likely -- that the features might be waves or floating debris.

Unfortunately for mystery lovers, the August Titan flyby marked the final opportunity for Cassini's radar to observe Kraken Mare. However, the spacecraft is scheduled to observe the original "magic island" feature in Ligeia Mare once more, in January 2015.


Image above: Cassini's radar instrument images show that a bright feature appeared in Kraken Mare, Titan's largest sea. Image Credit: NASA/JPL-Caltech/ASI/Cornell.

The August Titan flyby also included a segment designed to collect altimetry (or height) data, using the spacecraft's radar instrument along a 120-mile (200-kilometer) shore-to-shore track of Kraken Mare. For a 25-mile (40-kilometer) segment of this data along the sea's eastern shoreline, Cassini's radar beam bounced off the sea bottom and back to the spacecraft, revealing the sea's depth in that area. This region, which is near the mouth of a large, flooded river valley, showed depths of 66 to 115 feet (20 to 35 meters). Cassini will perform this experiment one last time in January 2015, to try to measure the depth of Punga Mare. Punga Mare is the smallest of three large seas in Titan's far north, and the only sea whose depth has not been observed by Cassini.

Scientists think that, for the areas in which Cassini did not observe a radar echo from the seafloor, Kraken Mare might be too deep for the radar beam to penetrate.  Alternatively, the signal over this region might simply have been absorbed by the liquid, which is mostly methane and ethane. The altimetry data for the area in and around Kraken Mare also showed relatively steep slopes leading down to the sea, which also suggests the Kraken Mare might indeed be quite deep.

Cassini Titan fly by. Image Credits: NASA/ESA

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. JPL, a division of the California Institute of Technology, Pasadena, manages the mission for NASA's Science Mission Directorate in Washington. The VIMS team is based at the University of Arizona in Tucson. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the US and several European countries.

More information about Cassini is available at the following sites: http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov and http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens

Images (mentioned), Text, Credits: NASA/JPL/Preston Dyches.

Greetings, Orbiter.ch