lundi 27 février 2017

NASA Satellite Spots Moon’s Shadow over Patagonia

NASA - EOS Terra Mission patch.

Feb. 27, 2017

On Feb. 26, 2017, an annular eclipse of the sun was visible along a narrow path that stretched from the southern tip of South America, across the Atlantic Ocean and into southern Africa. Those lucky enough to find themselves in the eclipse’s path saw a fiery ring in the sky. Meanwhile, NASA’s Terra satellite saw the eclipse from space.

Image above: NASA’s Terra satellite captured this image of the edges of the moon’s shadow over Patagonia at around 13:20 Universal Time (10:20 a.m. local time) on Feb. 26, 2017. Under the moon’s shadow, our planet’s surface and clouds appear yellowish-brown. Image Credits: NASA Goddard MODIS Rapid Response Team.

During an annular eclipse, the moon passes between the sun and Earth, blocking sunlight and casting a shadow on Earth. But the moon is too far from Earth to completely obscure the sun, so the sun peeks out around the moon. Looking down on Earth, the Moderate Resolution Imaging Spectroradiometer, or MODIS, aboard NASA’s Terra satellite spotted the moon’s shadow over Patagonia.

Image above: Observe the progression of the annular eclipse in this composite image taken from the shore of a small river near Chubut, Argentina. During an annular eclipse, the moon is too far from Earth to completely obscure the sun, so the sun peeks out around the moon in a visible ring. This ring is apparent at the very middle of the eclipse sequence. Image Credits: photo copyright Petr Horálek, used with permission.

Between two to four solar eclipses occur each year. Later this year, on Aug. 21, 2017, a total solar eclipse – in which the moon completely obscures the sun – will cross the United States, from Oregon to South Carolina. Visit to learn more:


Download additional multimedia on this story from NASA Goddard's Scientific Visualization Studio:

Total Solar Eclipse of Aug. 21, 2017:

NASA’s SDO Witnesses a Double Eclipse:

Eclipses and Transits:

Terra Satellite:

Images (mentioned), Text, Credits: NASA's Goddard Space Flight Center, by Lina Tran/Rob Garner.


Martian Winds Carve Mountains, Move Dust, Raise Dust

NASA - Mars Science Laboratory (MSL) logo.

Feb. 27, 2017

Animation above: This sequence of images shows a dust-carrying whirlwind, called a dust devil, scooting across ground inside Gale Crater, as observed on the local summer afternoon of NASA's Curiosity Mars Rover's 1,597th Martian day, or sol (Feb. 1, 2017). Timing is accelerated in this animation. Animation Credits: NASA/JPL-Caltech/TAMU.

On Mars, wind rules. Wind has been shaping the Red Planet's landscapes for billions of years and continues to do so today. Studies using both a NASA orbiter and a rover reveal its effects on scales grand to tiny on the strangely structured landscapes within Gale Crater.

NASA's Curiosity Mars rover, on the lower slope of Mount Sharp -- a layered mountain inside the crater -- has begun a second campaign of investigating active sand dunes on the mountain's northwestern flank. The rover also has been observing whirlwinds carrying dust and checking how far the wind moves grains of sand in a single day's time.

Gale Crater observations by NASA's Mars Reconnaissance Orbiter have confirmed long-term patterns and rates of wind erosion that help explain the oddity of having a layered mountain in the middle of an impact crater.

Image above: This map shows the two locations of a research campaign by NASA's Curiosity Mars rover mission to investigate active sand dunes on Mars. In late 2015, Curiosity reached crescent-shaped dunes, called barchans. In February 2017, the rover reached a location where the dunes are linear in shape. Image Credits: NASA/JPL-Caltech/Univ. of Arizona.

"The orbiter perspective gives us the bigger picture -- on all sides of Mount Sharp and the regional context for Gale Crater. We combine that with the local detail and ground-truth we get from the rover," said Mackenzie Day of the University of Texas, Austin, lead author of a research report in the journal Icarus about wind's dominant role at Gale.

The combined observations show that wind patterns in the crater today differ from when winds from the north removed the material that once filled the space between Mount Sharp and the crater rim. Now, Mount Sharp itself has become a major factor in determining local wind directions. Wind shaped the mountain; now the mountain shapes the wind.

The Martian atmosphere is about a hundred times thinner than Earth's, so winds on Mars exert much less force than winds on Earth. Time is the factor that makes Martian winds so dominant in shaping the landscape. Most forces that shape Earth's landscapes -- water that erodes and moves sediments, tectonic activity that builds mountains and recycles the planet's crust, active volcanism -- haven't influenced Mars much for billions of years. Sand transported by wind, even if infrequent, can whittle away Martian landscapes over that much time.

Animation above: This pair of images shows effects of one Martian day of wind blowing sand underneath NASA's Curiosity Mars rover on a non-driving day for the rover. Each image was taken just after sundown by the rover's Mars Descent Imager (MARDI). The area of ground shown spans about 3 feet left-to-right. Animation Credits: NASA/JPL-Caltech/MSSS.

How to Make a Layered Mountain

Gale Crater was born when the impact of an asteroid or comet more than 3.6 billion years ago excavated a basin nearly 100 miles (160 kilometers) wide. Sediments including rocks, sand and silt later filled the basin, some delivered by rivers that flowed in from higher ground surrounding Gale. Curiosity has found evidence of that wet era from more than 3 billion years ago. A turning point in Gale's history -- when net accumulation of sediments flipped to net removal by wind erosion -- may have coincided with a key turning point in the planet's climate as Mars became drier, Day noted.

Image above: The left side of this 360-degree panorama from NASA's Curiosity Mars rover shows the long rows of ripples on a linear shaped dune in the Bagnold Dune Field on the northwestern flank of Mount Sharp. The rover's Navigation Camera recorded the component images of this mosaic on Feb. 5, 2017. Image Credits: NASA/JPL-Caltech.

Scientists first proposed in 2000 that the mound at the center of Gale Crater is a remnant from wind eroding what had been a totally filled basin. The new work calculates that the vast volume of material removed -- about 15,000 cubic miles (64,000 cubic kilometers) -- is consistent with orbital observations of winds' effects in and around the crater, when multiplied by a billion or more years.

Other new research, using Curiosity, focuses on modern wind activity in Gale.

The rover this month is investigating a type of sand dune that differs in shape from dunes the mission investigated in late 2015 and early 2016. Crescent-shaped dunes were the feature of the earlier campaign -- the first ever up-close study of active sand dunes anywhere other than Earth. The mission's second dune campaign is at a group of ribbon-shaped linear dunes.

"In these linear dunes, the sand is transported along the ribbon pathway, while the ribbon can oscillate back and forth, side to side," said Nathan Bridges, a Curiosity science team member at the Johns Hopkins University Applied Physics Laboratory in Laurel, Maryland.

Animation above: Beyond a dark sand dune closer to the rover, a Martian dust devil passes in front of the horizon in this sequence of images from NASA's Curiosity Mars rover. The rover's Navigation Camera made this series of observations on Feb. 4, 2017, during the local afternoon in Mars' Gale Crater. Animation Credits: NASA/JPL-Caltech/TAMU.

The season at Gale Crater is now summer, the windiest time of year. That's the other chief difference from the first dune campaign, conducted during less-windy Martian winter.

"We're keeping Curiosity busy in an area with lots of sand at a season when there's plenty of wind blowing it around," said Curiosity Project Scientist Ashwin Vasavada of NASA's Jet Propulsion Laboratory, Pasadena, California. "One aspect we want to learn more about is the wind's effect on sorting sand grains with different composition. That helps us interpret modern dunes as well as ancient sandstones."

Before Curiosity heads farther up Mount Sharp, the mission will assess movement of sand particles at the linear dunes, examine ripple shapes on the surface of the dunes, and determine the composition mixture of the dune material.

Shifting Sand and 'Dust Devils'

Animation above: Dust devils dance in the distance in this sequence of images taken by the Navigation Camera on NASA's Curiosity Mars rover on Feb. 12, 2017, during the afternoon of the rover's 1,607th Martian day, or sol. Animation Credits: NASA/JPL-Caltech/TAMU.

Images taken one day apart of the same piece of ground, including some recent pairs from the downward-looking camera that recorded the rover's landing-day descent, show small ripples of sand moving about an inch (2.5 centimeters) downwind.

Meanwhile, whirlwinds called "dust devils" have been recorded moving across terrain in the crater, in sequences of afternoon images taken several seconds apart.

After completing the planned dune observations and measurements, Curiosity will proceed southward and uphill toward a ridge where the mineral hematite has been identified from Mars Reconnaissance Orbiter observations. The Curiosity science team has decided to call this noteworthy feature the "Vera Rubin Ridge," commemorating Vera Cooper Rubin (1928-2016), whose astronomical observations provided evidence for the existence of the universe's dark matter.

Animation above: This sequence of images shows a dust-carrying whirlwind, called a dust devil, on lower Mount Sharp inside Gale Crater, as viewed by NASA's Curiosity Mars Rover during the summer afternoon of the rover's 1,613rd Martian day, or sol (Feb. 18, 2017). Animation Credits: NASA/JPL-Caltech/TAMU.

As Curiosity focuses on the sand dunes, rover engineers are analyzing results of diagnostic tests on the drill feed mechanism, which drives the drill bit in and out during the process of collecting sample material from a rock. One possible cause of an intermittent issue with the mechanism is that a plate for braking the movement may be obstructed, perhaps due to a small piece of debris, resisting release of the brake. The diagnostic tests are designed to be useful in planning the best way to resume use of the drill.

The rover team is also investigating why the lens cover on Curiosity's arm-mounted Mars Hand Lens Imager (MAHLI) did not fully open in response to commands on Feb. 24. The arm has been raised to minimize risk of windborne sand reaching the lens while the cover is partially open. Diagnostic tests of the lens cover are planned this week.

During the first year after Curiosity's 2012 landing in Gale Crater, the mission fulfilled its main goal by finding that the region once offered environmental conditions favorable for microbial life. The conditions in long-lived ancient freshwater Martian lake environments included all of the key chemical elements needed for life as we know it, plus a chemical source of energy that is used by many microbes on Earth. The extended mission is investigating how and when the habitable ancient conditions evolved into conditions drier and less favorable for life. For more information about Curiosity, visit:

Animations (mentioned), Images (mentioned), Text, Credits: NASA/Laurie Cantillo/Dwayne Brown/Tony Greicius/JPL/Guy Webster.


First Solar Images from NOAA's GOES-16 Satellite

NOAA & NASA - GOES R Mission patch.

Feb. 27, 2017

The first images from the Solar Ultraviolet Imager or SUVI instrument aboard NOAA’s GOES-16 satellite have been successful, capturing a large coronal hole on Jan. 29, 2017.

The sun’s 11-year activity cycle is currently approaching solar minimum, and during this time powerful solar flares become scarce and coronal holes become the primary space weather phenomena – this one in particular initiated aurora throughout the polar regions. Coronal holes are areas where the sun's corona appears darker because the plasma has high-speed streams open to interplanetary space, resulting in a cooler and lower-density area as compared to its surroundings.

First Solar Imagery from GOES-16

Video above: This animation from January 29, 2017, shows a large coronal hole in the sun’s southern hemisphere from the Solar Ultraviolet Imager (SUVI) on board NOAA's new GOES-16 satellite. SUVI observations of solar flares and solar eruptions will provide an early warning of possible impacts to Earth’s space environment and enable better forecasting of potentially disruptive events on the ground. This animation captures the sun in the 304 Å wavelength, which observes plasma in the sun's atmosphere up to a temperature of about 50,000 degrees. When combined with the five other wavelengths from SUVI, observations such as these give solar physicists and space weather forecasters a complete picture of the conditions on the sun that drive space weather. Video Credits: NOAA/NASA.

SUVI is a telescope that monitors the sun in the extreme ultraviolet wavelength range. SUVI will capture full-disk solar images around-the-clock and will be able to see more of the environment around the sun than earlier NOAA geostationary satellites.

The sun’s upper atmosphere, or solar corona, consists of extremely hot plasma, an ionized gas. This plasma interacts with the sun’s powerful magnetic field, generating bright loops of material that can be heated to millions of degrees. Outside hot coronal loops, there are cool, dark regions called filaments, which can erupt and become a key source of space weather when the sun is active. Other dark regions are called coronal holes, which occur where the sun’s magnetic field allows plasma to stream away from the sun at high speed. The effects linked to coronal holes are generally milder than those of coronal mass ejections, but when the outflow of solar particles is intense – can pose risks to satellites in Earth orbit.

The solar corona is so hot that it is best observed with X-ray and extreme-ultraviolet (EUV) cameras. Various elements emit light at specific EUV and X-ray wavelengths depending on their temperature, so by observing in several different wavelengths, a picture of the complete temperature structure of the corona can be made. The GOES-16 SUVI observes the sun in six EUV channels.

Data from SUVI will provide an estimation of coronal plasma temperatures and emission measurements which are important to space weather forecasting. SUVI is essential to understanding active areas on the sun, solar flares and eruptions that may lead to coronal mass ejections which may impact Earth. Depending on the magnitude of a particular eruption, a geomagnetic storm can result that is powerful enough to disturb Earth’s magnetic field. Such an event may impact power grids by tripping circuit breakers, disrupt communication and satellite data collection by causing short-wave radio interference and damage orbiting satellites and their electronics. SUVI will allow the NOAA Space Weather Prediction Center to provide early space weather warnings to electric power companies, telecommunication providers and satellite operators.

Image above: These images of the sun were captured at the same time on January 29, 2017 by the six channels on the SUVI instrument on board GOES-16 and show a large coronal hole in the sun’s southern hemisphere. Each channel observes the sun at a different wavelength, allowing scientists to detect a wide range of solar phenomena important for space weather forecasting. Image Credit: NOAA.

SUVI replaces the GOES Solar X-ray Imager (SXI) instrument in previous GOES satellites and represents a change in both spectral coverage and spatial resolution over SXI.

NASA successfully launched GOES-R at 6:42 p.m. EST on Nov. 19, 2016, from Cape Canaveral Air Force Station in Florida and it was renamed GOES-16 when it achieved orbit. GOES-16 is now observing the planet from an equatorial view approximately 22,300 miles above the surface of Earth.

NOAA’s satellites are the backbone of its life-saving weather forecasts. GOES-16 will build upon and extend the more than 40-year legacy of satellite observations from NOAA that the American public has come to rely upon.

For more information about GOES-16, visit: or

To learn more about the GOES-16 SUVI instrument, visit:

NOAA Space Weather Prediction Center:

Image (mentioned), Text, Credits: NASA's Goddard Space Flight Center/Rob Gutro/Karl Hille/NOAA/Michelle Smith.


At the Center

NASA - Cassini International logo.

Feb. 27, 2017

The north pole of Saturn sits at the center of its own domain. Around it swirl the clouds, driven by the fast winds of Saturn. Beyond that orbits Saturn's retinue of moons and the countless small particles that form the ring.

Although the poles of Saturn are at the center of all of this motion, not everything travels around them in circles. Some of the jet-stream patterns, such as the hexagon-shaped pattern seen here, have wavy, uneven shapes. The moons as well have orbits that are elliptical, some quite far from circular.

This view looks toward the sunlit side of the rings from about 26 degrees above the ring plane. The image was taken with the Cassini spacecraft wide-angle camera on Dec. 2, 2016 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 890 nanometers.

The view was acquired at a distance of approximately 619,000 miles (996,000 kilometers) from Saturn. Image scale is 37 miles (60 kilometers) per pixel.

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 and The Cassini imaging team homepage is at and ESA's website:

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

Best regards,

Science checkout continues for ExoMars orbiter

ESA & ROSCOSMOS - ExoMars Mission patch.

27 February 2017

Trace Gas Orbiter at Mars

Next week, the ExoMars orbiter will devote two days to making important calibration measurements at the Red Planet, which are needed for the science phase of the mission that will begin next year.

The Trace Gas Orbiter (TGO), a joint endeavour between ESA and Roscosmos, arrived at Mars on 19 October. During two dedicated orbits in late November, the science instruments made their first calibration measurements since arriving at Mars. These included images of Mars and one of its moons, Phobos, and basic spectral analyses of the martian atmosphere.

ExoMars science orbit 5–6 March

At that time, the orbiter was in a highly elliptical path that took it from between 230 and 310 km above the surface to around 98 000 km every 4.2 days.

The main science mission will only begin once it reaches a near-circular orbit about 400 km above the planet’s surface after a year of ‘aerobraking’ – using the atmosphere to gradually brake and change its orbit.

Earlier this year, in preparation for the aerobraking phase, TGO conducted a series of manoeuvres to shift its angle of travel with respect to the planet’s equator to almost 74º. This raised it from a near-equatorial arrival orbit to one that flies over more of the northern and southern hemispheres.

This inclination will provide optimum coverage of the surface for the science instruments, while still offering good visibility for relaying data from current and future landers – including the ExoMars rover scheduled for launch in 2020.

ExoMars science orbit 6–7 March

Now, before the year-long aerobraking phase begins on 15 March, the science teams once again have the opportunity to make important calibration measurements, focusing mainly on tests to check the pointing and tracking of the instruments, but this time from the new orbit.

The spacecraft’s new one-day orbit takes it from 37 150 km at its farthest and to within about 200 km of the planet’s surface at its closest approach, which will also allow some of the closest images of the mission to be obtained.

TGO’s two spectrometer suites will make some preliminary calibration observations on 28 February and 1 March while the spacecraft’s instruments are facing towards Mars, with the main campaign taking place 5–7 March, covering two complete orbits of the planet.

During the main campaign, the spectrometers will be able to test another operational mode, such as scanning towards the horizon at sunlight scattered by the atmosphere.

By looking at how the sunlight is influenced by the atmosphere, scientists will be able to analyse the atmospheric constituents of Mars – TGO’s main science goal.

Indeed, TGO is tasked with making a detailed inventory of the atmosphere, particularly those gases that are present only in trace amounts. Of high interest is methane, which on Earth is produced primarily by biological activity or geological processes such as some hydrothermal reactions. 

ExoMars first year in orbit

The spacecraft will also seek out water or ice just below the surface, and will provide colour and stereo context images of surface features, including those that may be related to possible trace gas sources.

During the upcoming observations, and in addition to pointing directly at the planet’s surface, the camera will also take important dark sky and star field calibration measurements.

Meanwhile TGO’s neutron detector will be on throughout the two orbits in order to calibrate the background flux.

“It’s great we have the opportunity to squeeze in these important observations during this very busy time preparing for the year-long aerobraking phase,” says Håkan Svedhem, ESA’s TGO project scientist. “While the aerobraking is taking place, the science teams will be able to use these essential calibration measurements to best prepare for the start of the main mission when we arrive in our science orbit next year.”

Related links:


Robotic exploration of Mars:

Mars Express:


ExoMars at IKI:

Thales Alenia Space:

NASA In 2016 ExoMars orbiter (Electra radio):

Where on Mars?:

ExoMars for broadcasters:

Images, Video, Text, Credits: ESA/Markus Bauer/Håkan Svedhem/C. Carreau/CC BY-SA 3.0 IGO/ATG medialab.

Best regards,

vendredi 24 février 2017

Weekly Recap From the Expedition Lead Scientist, week of Feb. 13, 2017

ISS - Expedition 50 Mission patch.

Feb. 24, 2017

International Space Station (ISS). Animation Credit: NASA

(Highlights: Week of Feb. 13, 2017) - It was harvest week for another crop of vegetables on the International Space Station.

NASA astronaut Peggy Whitson photographed and harvested Tokyo Bekana cabbage – also known as Chinese cabbage – capping another round of the Veg-03 investigation. Understanding how plants respond to microgravity is an important step for future long-duration space missions, which will require crew members to grow their own food. Astronauts on the station have previously grown lettuce and flowers in the Veggie facility. This new series of the study expanded on previous validation tests. Whitson froze some of the crop for return to Earth, and set aside some for mealtime with the crew before cleaning and drying the facility.

Veggie provides lighting and necessary nutrients for plants by using a low-cost growth chamber and planting pillows, which deliver nutrients to the root system. The Veggie pillow concept is a low-maintenance, modular system that requires no additional energy beyond a special light to help the plants grow. It supports a variety of plant species that can be cultivated for fresh food, and even for education experiments.

Image above: NASA astronaut Shane Kimbrough works on the Capillary Flow Experiment on the space station. This study examines how liquid flows in space and could improve the reliability of water purification, fuels storage and supply, and general liquid transport on spacecraft. Image Credit: NASA.

Crew members have commented that they enjoy space gardening, and investigators believe growing plants could provide a psychological benefit to crew members on long-duration missions, just as gardening is often an enjoyable hobby for people on Earth. Data from this investigation could benefit agricultural practices on Earth by designing systems that use valuable resources such as water more efficiently.

ESA (European Space Agency) astronaut Thomas Pesquet completed over 15 test runs for the final operations of the Capillary Flow Experiment (CFE-2), working with the ground team to collect important data for new mathematical models of liquid flow types. Liquids behave differently in space than they do on Earth, so containers that can process, hold or transport them must be designed carefully to work in microgravity. The Capillary Flow Experiment furthers research on wetting, which is a liquid’s ability to spread across a surface. The study demonstrates how capillary forces work in space, how differently shaped containers change the wicking behavior of a wetting fluid, and how such can be used to passively separate liquids and gases. Understanding how microgravity amplifies these behaviors could improve the reliability of such key processes as water purification, fuel storage and supply, and general liquid transport aboard spacecraft.

Image above: NASA astronaut Peggy Whitson harvested Tokyo Bekana cabbage – also known as Chinese cabbage – capping another round of the Veg-03 investigation. Image Credit: NASA.

On Earth, capillary action allows small amounts of liquid to flow up and into tight spaces despite the effects of gravity. New miniature medical devices, known as lab-on-a-chip technologies, exploit this phenomenon to draw blood or other fluids into essentially miniature diagnostic systems. CFE-2 improves our understanding of how capillary forces work in a variety of system geometries including the open spaces within porous materials such as sand and soil, wicks and sponges.

NASA astronaut Shane Kimbrough moved the Simple Solar Neutron Detector from the U.S. Lab to Node 1, continuing the study of solar radiation on the space station. Like any star, our sun gives off neutron radiation. The physical properties of neutrons, in particular the absence of electric charge, presents significant challenges to their detection. Astronauts are particularly sensitive to low-energy neutron exposure, which has adverse health consequences, and can cause materials fatigue and degradation issues if spacecraft components are exposed to solar neutrons over long periods.

Image above: ESA astronaut Thomas Pesquet and NASA astronaut Peggy Whitson setup the Microgravity Science Glovebox (MSG) in preparation for the Expanded Stem Cells investigation. Image Credit: NASA.

This investigation from the University of Nebraska in Lincoln involves a new type of detector on the station to measure solar neutrons of lower energy. In addition to confirming decades-long predictions that the sun generates neutrons, the project investigates radiation damage and materials fatigue associated with these neutrons. A space-based approach is essential to this task, since ground-based neutron detectors are subject to interference as interactions of energetic particles with the atmosphere create secondary, non-solar neutrons.

Human research investigations conducted this week include Biochemical Profile, Repository, Fine Motor Skills, Habitability, Space Headaches, Multi-Omics, and Dose Tracker.

Progress was made on other investigations, outreach activities, and facilities this week, including Microgravity Expanded Stem Cells, Rodent Research-4, EPO Pesquet, Google Street View, ISS Ham Radio, Group Combustion, JAXA Electrostatic Levitation Furnace, Plasma Kristall-4, Robotic External Leak Locator, NanoRacks CubeSat Deployer, RFID Logistics Awareness, Robonaut, SPHERES-UDP, and Manufacturing Device.

Related links:


Veggie facility:

Capillary Flow Experiment (CFE-2):

Simple Solar Neutron Detector:

Biochemical Profile:


Fine Motor Skills:


Space Headaches:


Dose Tracker:

Microgravity Expanded Stem Cells:

Rodent Research-4:

ISS Ham Radio:

Group Combustion:

JAXA Electrostatic Levitation Furnace:

Plasma Kristall-4:

Robotic External Leak Locator:

NanoRacks CubeSat Deployer:

RFID Logistics Awareness:



Manufacturing Device:

Space Station Research and Technology:

International Space Station (ISS):

Animation (mentioned), Images (mentioned), Text, Credits: NASA/Kristine Rainey/Vic Cooley, Lead Increment Scientist Expeditions 49 & 50.

Best regards,

Hardy Objects in Saturn's F Ring

NASA - Cassini Mission to Saturn patch.

Feb. 24, 2017

As NASA & ESA Cassini spacecraft continues its weekly ring-grazing orbits, diving just past the outside of Saturn's F ring, it is tracking several small, persistent objects there.

These images show two such objects that Cassini originally detected in spring 2016, as the spacecraft transitioned from more equatorial orbits to orbits at increasingly high inclination about the planet's equator.

Imaging team members studying these objects gave them the informal designations F16QA (right image) and F16QB (left image). The researchers have observed that objects such as these occasionally crash through the F ring's bright core, producing spectacular collisional structures (see PIA08863), similar to those created in 2006 and 2007 by the object designated S/2004 S 6 (see PIA07716).

While these objects may be mostly loose agglomerations of tiny ring particles, scientists suspect that small, fairly solid bodies lurk within each object, given that they have survived several collisions with the ring since their discovery. The faint retinue of dust around them is likely the result of the most recent collision each underwent before these images were obtained.

The researchers think these objects originally form as loose clumps in the F ring core as a result of perturbations triggered by Saturn's moon Prometheus (see PIA08397 and PIA08947). If they survive subsequent encounters with Prometheus, their orbits can evolve, eventually leading to core-crossing clumps that produce spectacular features, even though they collide with the ring at low speeds.

The images were obtained using the Cassini spacecraft narrow-angle camera on Feb. 5, 2017, at a distance of 610,000 miles (982,000 kilometers, left image) and 556,000 miles (894,000 kilometers, right image) from the F ring. Image scale is about 4 miles (6 kilometers) per pixel.

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.

Related links:





For more information about the Cassini-Huygens mission visit and The Cassini imaging team homepage is at and ESA's website:

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

Best regards,