Near-infrared image of the Moon's surface by NASA's Moon Mineralogy Mapper on the Indian Space Research Organization's Chandrayaan-1 mission
Image credit: ISRO/NASA/JPL-Caltech/Brown Univ./USGS
When they first set foot on the Moon, the Apollo 11 astronauts painted a picture of the landscape as a bone-dry desert. So astronomers were naturally surprised when in 2009, three probes showed that a lot of water is locked up in minerals in the soil. There has been some debate as to where the water came from, but now two researchers with the National Museum of Natural History in Paris, France, have determined that most of the water in the soil on the surface of the Moon was formed due to protons in the solar wind colliding with oxygen in lunar dust, rather than from comet or meteorite impacts.
The first hints that there was water on the Moon came when India’s Chandrayaan-1 found hints of water across the lunar surface when it measured a dip in reflected sunlight at a wavelength absorbed only by water and hydroxyl, a molecule that contains one atom of hydrogen and one atom of oxygen.
This colorized mosaic from NASA's Cassini mission shows the most complete view yet of Titan's northern land of lakes and seas. Saturn's moon Titan is the only world in our solar system other than Earth that has stable liquid on its surface. The liquid in Titan's lakes and seas is mostly methane and ethane. Image credit: NASA/JPL-Caltech/ASI/USGS
There’s a very early-stage NASA concept to take a submarine and dive into a lake of Titan, that moon of Saturn that has chemistry that could prove to be a similar precursor to what eventually formed life on Earth. The moon has weather and a hydrological system and an atmosphere, making it an exciting location for astrobiologists.
Luckily for scientists, the Cassini spacecraft beams back regular updates on what it sees at Titan. And this week comes yet another opportunity, as the machine whizzes by the moon to look for “mirror-like surface echoes” in a lake-filled region in Titan’s northern sector.
Principal among the targets will be Kraken Mare, a liquid hydrocarbon sea that is about five times the size of Lake Superior in North America. It’s an astounding 154,000 square miles (400,000 square kilometers). On this pass, Cassini is going to sail over the eastern area of the sea.
“Measurements of the absolute strength of the echo and its polarization properties, when detectable, yield important information about the surface status (liquid/solid), surface reflectivity, surface dielectric constant and implied composition, and surface roughness,” Cassini’s website says in a description of the T-106 flyby, which will take place Thursday (Oct. 23).
Saturn’s moon Titan with Tethys hovering in the background. Image taken by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute
This is the second-to-last flyby Cassini will have of Titan in 2014, with the last one coming Dec. 10. In that case, the focus will be learning more about Titan’s atmosphere to learn more about measurement differences obtained by instruments on Cassini.
This past week, meanwhile, Titan has been busy looking at Saturn. It examined a northern aurora, looked at the planet’s F ring, and also searched for small satellites.
Scientists have been working at Saturn for the past 10 years with the Cassini mission, which is now entering a new phase as Saturn enters northern summer. This is expected to produce more changes on Titan, such as winds picking up, as more sunlight strikes the surface and atmosphere.
A false-color view of Saturn's moon Hyperion taken during a Cassini flyby in September 2005. Credit: NASA/JPL-Caltech/Space Science Institute
Ever taken a balloon and rubbed it against your hair? That’s an example of electrostatic charging, which you see as the balloon briefly attracts strands of hair against your head. Turns out a similar process is taking place on Saturn’s moon Hyperion. More astounding, it wasn’t until recently that scientists saw a curious effect on the Cassini spacecraft in 2005.
As the machine whizzed by the small moon, Cassini was blanketed in electrons from Hyperion’s electrostatically charged surface. It’s the first time scientists have seen static electricity in effect on any airless body outside of the Moon.
The charge comes partly from massive Saturn’s magnetic field, which hits Hyperion’s spongy surface constantly with electrons and ions. The Sun also plays a role, sending ultraviolet light that also strikes the moon’s surface. Scientists found out this happens while studying old data on the Cassini spacecraft, when they discovered “something unexpected” during a close flyby of Hyperion in September 2005.
NASA’s Cassini spacecraft obtained this unprocessed image of Saturn’s moon Hyperion on Aug. 25, 2011. Image credit: NASA/JPL-Caltech/Space Science Institute
Specifically, the spacecraft — which is still in operation today — was briefly connected through magnetism to Hyperion’s surface, receiving a surge of electrons. Cassini emerged from the encounter unharmed, even though team members estimate that it received the equivalent of a 200-volt shock from the moon. Charging events can hurt spacecraft, making this a valuable thing to know about for future missions.
“Our observations show that this is also an important effect at outer planet moons and that we need to take this into account when studying how these moons interact with their environment,” stated Geraint Jones of Mullard Space Science Laboratory (MSSL), University College London. He is a member of the Cassini Plasma Spectrometer (CAPS) team and one of the study’s supervisors.
CAPS is not in operation any more, since the instrument was turned off due to drawing excess current in 2012. But perhaps some of its past data, and observations from other Cassini instruments, can help unveil evidence of charging on other moons.
The tumbling motion of elongated Eros creates a changing brightness. (via transitofvenus.nl)
Previous research concerning some of Saturn’s moons, and the asteroid Eros, suggests that charged dust can move across the surface and perhaps even be able to sail into space against the force of gravity.
Several other instruments were used to gather data for this analysis, including Cassini’s magnetometer, magnetospheric imaging instrument, and radio and plasma wave science instrument.
You can read more about the research, which was led by Tom Nordheim, an MSSL doctoral candidate, in Geophysical Research Letters.
A view of Mimas from the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute
Could there be an ocean hidden somewhere in that Death Star-like picture? This is an image of Mimas, a moon of Saturn, and just yesterday (Oct. 15) newly released data from the Cassini spacecraft suggests there are big liquid reservoirs underneath its surface.
“The amount of the to-and-fro motion indicates that Mimas’ interior is not uniform. These wobbles can be produced if the moon contains a weirdly shaped, rocky core or if a sub-surface ocean exists beneath its icy shell,” said Cornell University in a press release. More flybys with the Cassini spacecraft will be required to learn more about what lies beneath.
You can read more about the study (led by Cornell astronomy research associate Radwan Tajeddine) in Science, where it was published. Below, learn more about other worlds in the Solar System that could host oceans under their surface.
Enceladus
Cassini images of Saturn’s moon Enceladus backlit by the sun show the fountain-like sources of the fine spray of material that towers over the south polar region. This image was taken looking more or less broadside at the “tiger stripe” fractures observed in earlier Enceladus images. It shows discrete plumes of a variety of apparent sizes above the limb (edge) of the moon. This image was acquired on Nov. 27, 2005. Image Credit: NASA/JPL/Space Science Institute
After nearly a decade of speculation, this year the Cassini spacecraft returned gravity data suggesting Enceladus (another moon of Saturn) does have a large subsurface ocean near its south pole, if not a global ocean. If confirmed, that could help explain why scientists see water gushing out of fractures in that area. As this recent paper by Cassini scientists shows, Enceladus is a promising location for habitability.
Titan
A halo of light surrounds Saturn’s moon Titan in this backlit picture, showing its atmosphere. Credit: NASA/JPL/Space Science Institute
By the way, anyone noticed that we still haven’t even left Saturn’s system? Titan is usually high on astrobiology wish lists for researchers because its hydrocarbon chemistry could be precursors to how life evolved. What’s not talked about as much, though, is at least two research findings pointing to evidence of a hidden ocean. Evidence comes from Titan’s tidal flexing from interacting with Saturn — which is 10 times more than what would be expected with a solid core — and the way that it moves on its own axis as well as around Saturn.
Europa
Rendering showing the location and size of water vapor plumes coming from Europa’s south pole. Credit: NASA/ESA/L. Roth/SWRI/University of Cologne
That Minecraft-looking object floating beside Europa there is a rendering showing where water vapor erupted from the Jovian moon, spotted by the Hubble Space Telescope in 2013. We were lucky enough to have a close-up view of Europa in the 1990s and early 2000s courtesy of NASA’s Galileo spacecraft. What we know for sure is there’s thick ice on Europa. What’s underneath is not known, but there’s long been speculation that it could be a subsurface ocean that may have more water than our own planet.
Io
Jupiter’s volcanic moon Io , imaged by the Galileo spacecraft in 1997. Credit: NASA/JPL/University of Arizona
Still flying around Jupiter here, we now turn our attention to Io — a place that is often remarked upon because of its blotchy appearance as well as all of the volcanoes on its surface. A newer analysis of Galileo data in 2011 — looking at some of the lesser-understood magnetic field data signatures — led one research team to conclude there could be a magma ocean lurking underneath that violence.
Triton
A glimpse of Triton from the Voyager 2 spacecraft, which flew by the Neptunian moon in August 1989. Credit: NASA/JPL
Little is known about Triton because only one spacecraft whizzed by it — Voyager 2, which took a running pass through the Neptune system in August 1989. An Icarus paper two years ago speculated that the world could host a subsurface ocean, but more data is needed. The energy of Neptune (which captured Triton long ago) could have melted its interior through tidal heating, possibly creating water from the ice in its crust.
Charon
Hubble image of Pluto and some of its moons, Charon, Nix and Hydra. Image Credit: NASA, ESA, H. Weaver (JHU/APL), A. Stern (SwRI), and the HST Pluto Companion Search Team
We don’t have any close-up pictures of this moon of Pluto yet, but just wait a year. The New Horizons spacecraft will zoom past Charon and the rest of the system in July 2015. In the meantime, however, findings based on a model came out this summer in Icarus suggesting Charon — despite being so far from the Sun — might have had a subsurface ocean in the past. Or even now. The key is its once eccentric orbit, which would have produced tidal heating while interacting with Pluto. The science team plans to look for cracks that could be indicative of “the structure of the moon’s interior and how easily it deforms, and how its orbit evolved,” stated Alyssa Rhoden of NASA’s Goddard Space Flight Center in Maryland, who led the research.
Three images – spanning more than seven years – of Titan’s Ligeia Mare in which an elusive, radar-bright feature has been spotted. Images were created from data collected by Cassini’s Synthetic Aperture Radar (SAR). Image credit: NASA/JPL-Caltech/ASI/Cornell
Earlier this year, we reported on a mysterious “ghost” object that had suddenly appeared and then disappeared on Saturn’s largest moon, Titan. Now, new observations by the Cassini team show this elusive feature is back again.
You may recall that a so-called “transient feature,” nicknamed “Magic Island” by the Cassini team, was first observed by Cassini in July 2013 during a Titan flyby. Magic Island has continued to puzzle scientists because shortly after its initial appearance, it disappeared and has been in hiding ever since. That is, until it just-as-suddenly reappeared in images created using SAR data collected in mid-August, 2014.
However, with its reemergence comes additional questions for scientists since its physical appearance has changed rather significantly, having roughly doubled in size during its 13 months in hiding, growing from 30 square miles [75 square km] in 2013 to almost 60 square miles [160 square km], as seen in the latest images, above.
Although scientists initially considered that this had been a transient feature, they now suspect that its appearance and disappearance may be the result of Titan’s changing seasons. (Titan is currently entering summer in its northern hemisphere.) There has also been some speculation that the feature may be rising gas bubbles, surface waves, or solid material at (or just below) the surface of Ligeia Mare.
Titan’s seas are made of liquid methane and ethane, organic compounds which are gases on Earth but liquids in Titan’s incredibly chilly -290º F (-180º C) environment.
“Science loves a mystery, and with this enigmatic feature, we have a thrilling example of ongoing change on Titan,” said Stephen Wall, the deputy team lead of Cassini’s radar team, based at NASA’s Jet Propulsion Laboratory in Pasadena, California. “We’re hopeful that we’ll be able to continue watching the changes unfold and gain insights about what’s going on in that alien sea.”
The monitoring of Titan’s changing climate and surface features is a primary goal of Cassini’s ongoing, and twice-extended, mission. Further studies may confirm or eliminate explanations that have been presented to date – or they may lead to completely new hypotheses about mysteries held within and below Titan’s seas.
Titan’s Ligeia Mare. Credit: NASA/JPL/USGS
In addition to its original primary mission, Cassini, which was launched in October 1997 and entered Saturn’s orbit on July 1, 2004, has been extended two times – the Extended Equinox Mission in July 2008, and the Solstice Mission in November, 2010. In September, 2014, NASA announced that it had fully funded Cassini through its planned completion in 2017.
For more information about Cassini and its ongoing mission, visit:
Titan's thick haze. Image: NASA/JPL/Space Science Institute.
Is the surf up yet on Titan? As the moon of Saturn moves towards northern summer, scientists are trying to spot signs of the winds picking up. This weekend, the Cassini spacecraft plans a look at the the largest body of liquid on Titan, Kraken Mare, to see if there are any waves on this huge hydrocarbon sea.
Cassini will make the 105th flyby of Titan on Monday (Sept. 22) to probe the moon’s atmosphere, seas and even a crater. The spacecraft will examine “the seas and lakes of the northern polar area, including Kraken and Ligeia at resolution better than 3 miles (5 kilometers) per pixel,” the Cassini website stated.
Besides wet areas of Titan, Cassini will also look at dunes and the relatively fresh-looking Sinlap crater, where scientists hope to get a high-resolution image. Managers also plan a mosaic of Tsegihi — a bright zone south of the equator — and the darker dune-filled area of Fensal. The spacecraft additionally will examine aerosols and the transparency of hazes in Titan’s atmosphere.
Titan is of interest to scientists in part because its chemistry is a possible precursor to what made life possible. Earlier this week, Cassini transmitted several raw images of its view of Titan and Saturn right now — some of the latest pictures are below.
A raw image of Saturn’s moon Titan taken by the Cassini spacecraft Sept. 14, 2014. Credit: NASA/JPL/Space Science InstituteAtmospheric features on Saturn’s moon Titan appear to be faintly visible in this raw image taken by the Cassini spacecraft Sept. 10, 2014. Credit: NASA/JPL/Space Science InstituteA crescent Titan beckons the Cassini spacecraft (in Saturn’s system) in this image taken Aug. 24, 2014. Credit: NASA/JPL/Space Science InstituteA raw image of Saturn taken by the Cassini spacecraft Sept. 15, 2014. Credit: NASA/JPL/Space Science Institute
NASA's Mars rover Curiosity took this self-portrait, composed of more than 50 images using its robotic arm-mounted MAHLI camera, on Feb. 3, 2013. The image shows Curiosity at the John Klein drill site. A drill hole is visible at bottom left. Credit: NASA / JPL / MSSS / Marco Di Lorenzo / Ken Kremer- kenkremer.com
NASA’s planetary senior review panel harshly criticized the scientific return of the Curiosity rover in a report released yesterday (Sept. 3), saying the mission lacks focus and the team is taking actions that show they think the $2.5-billion mission is “too big to fail.”
While the review did recommend the mission receive more funding — along with the other six NASA extended planetary missions being scrutinized — members recommended making several changes to the mission. One of them would be reducing the distance that Curiosity drives in favor of doing more detailed investigations when it stops.
The role of the senior review, which is held every two years, is to help NASA decide what money should be allocated to its extended missions. This is important, because the agency (as with many other departments) has limited funds and tries to seek a balance between spending money on new missions and keeping older ones going strong.
Engineering acumen means that many missions are now operating well past their expiry dates, such as the Cassini orbiter at Saturn and the Opportunity rover on Mars. In examining the seven missions being reviewed, the panel did recommend keeping funding for all, but said that 4/7 are facing significant problems.
Opportunity rover’s 1st mountain climbing goal is dead ahead in this up close view of Solander Point at Endeavour Crater. Opportunity has ascended the mountain looking for clues indicative of a Martian habitable environment. This navcam panoramic mosaic was assembled from raw images taken on Sol 3385 (Aug 2, 2013). Credit: NASA/JPL/Cornell/Marco Di Lorenzo/Ken Kremer (kenkremer.com)
In the case of Curiosity, the panel called out principal investigator John Grotzinger for not showing up in person on two occasions, preferring instead to interact by phone. The review also said there is a “lack of science” in its extended mission proposal with regard to “scientific questions to be answered, testable hypotheses, and proposed measurements and assessment of uncertainties and limitations.”
Other concerns were the small number of samples over the prime and extended missions (13, a “poor science return”), and a lack of clarity on how the ChemCam and Mastcam instruments will play into the extended mission. Additionally, the panel expressed concern that NASA would cut short its observations of clays (which could help answer questions of habitability) in favor of heading to Mount Sharp, the mission’s ultimate science destination.
“In summary, the Curiosity … proposal lacked scientific focus and detail,” the panel concluded, adding in its general recommendations for the reviews that principal investigators must be present to avoid confusion while answering questions. The other missions facing concern from the panel included the Lunar Reconnaissance Orbiter, Mars Express and Mars Odyssey.
Lunar Reconnaissance Orbiter. Image Credit: NASA
LRO: Its extended mission (the second) is supposed to look at how the moon’s surface, subsurface and exosphere changes through processes such as meteorites and interaction with space. The panel was concerned with a “lack of detail” in the proposal and in answers to follow-up questions. The panel also recommended turning off certain instruments “at the end of their useful science mission”.
Mars Express: The extended mission is focusing on the ionosphere and atmosphere as well as the planet’s surface and subsurface. Concerns were raised about matters such as why funding is needed to calibrate its high-resolution stereo camera after 11 years — especially given the instrument has been rarely cited in published journal reports lately — and how people involved in the extended mission would meet the goals. The panel also saw a “lack of communication” in the team.
Mars Odyssey: If approved, the spacecraft will move to the day/night line of Mars to look at the planet’s radiation, gamma rays, distribution of water/carbon dioxide/dust in the atmosphere, and the planet’s surface. The panel, however, said there are no “convincing arguments” as to how the new science relates to the Decadal Survey objectives for planetary science. Odyssey, which is in its 11th year, may also be nearing the end of its productive lifespan given fewer publications using its data in recent years, the panel said.
The panel also weighed in on the success of the Cassini and Opportunity missions:
Artist’s conception of the Mars Odyssey spacecraft. Credit: NASA/JPL
Cassini received the highest rating — “Excellent” — due to its scientific merit, the only mission this time around to do so. The panel was particularly excited about seasonal changes that will be seen on Titan in the coming years, as well as measurements of Saturn’s rings and magnetosphere and its icier moons (such as Enceladus). The spacecraft is noted to be in good condition and the new mission will be a success because of “the unique aspect of the new observations.”
Opportunity, which is more than 10 years into its Mars exploration, is still “in sufficiently good condition” to do science, although the panel raised concerns about software and communication problems. The panel, however, said more time with the rover would allow it to look for evidence of past water on Mars that would not be visible from orbit — even though it’s unclear if phyllosilicates around its current location (Endeavour crater) are from the Noachian period, the earliest period in Mars’ history.
The panel is just one step along the road to figuring out how NASA chooses to spend its money in the coming years. Funding availability depends on how much money Congress allocates to the agency.
An illustration of a Titanic lake by Ron Miller. All rights reserved. Used with permission.
Titan — that moon of Saturn that has what some scientists consider precursors to elements for life — is a neat place to study because it also has a liquid cycle. But how the hydrocarbons move from the moon’s hundreds of lakes and seas into the atmosphere and the crust is still being examined.
A new study suggests that rainfall on Titan changes when it interacts with underground icy clathrates, which are watery structures that can include methane or ethane. This can make it easier for reservoirs to be created.
“We knew that a significant fraction of the lakes on Titan’s surface might possibly be connected with hidden bodies of liquid beneath Titan’s crust, but we just didn’t know how they would interact,” stated lead author Olivier Mousis, a Cassini research associate at the University of Franche-Comté in France. “Now, we have a better idea of what these hidden lakes or oceans could be like.”
Artist’s conception of a possible structure for underground liquid reservoirs on Saturn moon’s Titan. From top, the layers include a porous icy crust, alkanofer in porous icy crust, expanding clathrate layer in porous icy crust and a non-porous icy crust. Credit: ESA/ATG medialab
This information is based on models of how the reservoirs would move through the crust of the icy moon. Clathrates would form at the bottom of reservoirs (which are filled with methane) and gradually split its molecules into solid and liquid components. Over time, this would transform the methane into propane or ethane.
“Importantly, the chemical transformations taking place underground would affect Titan’s surface,” the Jet Propulsion Laboratory stated.
“Lakes and rivers fed by springs from propane or ethane subsurface reservoirs would show the same kind of composition, whereas those fed by rainfall would be different and contain a significant fraction of methane. This means researchers could examine the composition of Titan’s surface lakes to learn something about what is happening deep underground.”
More about the research is available in the print version of the Sept. 1 edition of Icarus. Of note, the Cassini spacecraft is going to do another flyby of Titan in 17 days — its 105th, according to the spacecraft website.
Sunlight and shadow combine in this photo of Saturn and its rings taken Aug. 19, 2014. Credit: NASA/JPL/Space Science Institute
When Saturn is at its closest to Earth, it’s three-quarters of a billion miles away — or more than a billion kilometers! That makes these raw images from the ringed planet all the more remarkable.
Nearly every day, the Cassini spacecraft beams back what it sees at Saturn and the images are put up on this NASA website. This week, for example, it was checking out Saturn’s rings. We have a few of the pictures below, plus an older picture of the entire planet for reference.
Saturn’s rings are believed to be about 4.4 billion years old — that’s close to the age of the Solar System itself. Astronomers, however, have only known about them since the 1600s, when Galileo Galilei was trying to make sense of some funny-looking shapes on either side of the planet in his telescope.
According to NASA, the particles in the rings range from dust-sized to mountain-sized. Some of Saturn’s dozens of moons act as shepherds to the rings, keeping gaps open. You can read more about what we know about their origins here.
The Cassini spacecraft looks to the side of Saturn’s rings in this picture from Aug. 19, 2014. Credit: NASA/JPL/Space Science InstituteBands prominently feature in this raw picture of Saturn taken by the Cassini spacecraft Aug. 17, 2014. Credit: NASA/JPL/Space Science InstituteDifferent shades shine in this raw image of Saturn’s rings taken by the Cassini spacecraft taken Aug. 19, 2014. Credit: NASA/JPL/Space Science InstituteSaturn and its rings, as seen from above the planet by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute. Assembled by Gordan Ugarkovic.
The shadow of the Opportunity rover lies on the Martian surface in this picture taken on Sol 3752, on Aug. 13. The rover is on the west rim of Endeavour Crater, near the Martian equator. Its landing site was Meridani Planum. Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.
Many of us in the northern hemisphere are on summer vacation right now, and others are dreaming of it. While taking off somewhere exotic requires time and money, looking at pictures around the solar system provides cheaper thrills — in stranger places!
Several spacecraft roaming our planetary neighborhood regularly send back raw images of what they’re seeing. Here are some views from them taken in the past week.
Mars: After setting an off-word driving record, the Opportunity rover is still trundling on Mars after more than 10 years of operations. One of its latest raw images, above, shows its shadow and tracks on the surface of the Red Planet. Its heading to a destination called “Marathon Valley”, which is a likely spot for clay materials, and recently observed a transit of the moon Phobos. The rover’s computer had a brief reset, but is in good health besides that.
Tracks of the Curiosity rover crisscross Mars in this picture taken on Sol 719 (Aug. 14, 2014). Credit: NASA/JPL-Caltech
Mars: The Curiosity rover — which recently celebrated its two-year Earth birthday on Mars — has been on the move itself. Scientists are carefully moving the rover to its next science destination, about 1/3 of a mile (500 meters) away. The challenge is the extremely rocky terrain is damaging the rover’s wheels, but NASA said a recent drive through a rocky stretch produced less wear than feared.
A lava surface in southern Elysium Planitia taken by the Mars Reconnaissance Orbiter’s High Resolution Imaging Science Experiment (HiRISE). Credit: NASA/JPL/University of Arizona
Mars: These strange features spotted by the Mars Reconnaissance Orbiter are puzzling scientists. Usually the cones you see are indicative of lava features, but these are smaller than usual. “What’s really odd here is that the cones are associated with lighter areas with polygonal patterns,” stated the University of Arizona on its blog for the High Resolution Imaging Science Experiment (HiRISE). “Such polygons are commonly visible on the denser portions of lava flows, while the rougher areas have more broken-up low-density crust.”
A raw image of the Sun taken by the Solar and Heliospheric Observatory (SOHO) on Aug. 15, 2014. Credit: ESA/NASA/SOHO
Sun: The Solar and Heliospheric Observatory (SOHO) is one of a few sentinels keeping watch over the Sun for sunspots and other signs of solar activity. This allows scientists to make better predictions about when solar storms sweep over our planet, which is important for protecting satellites and infrastructure from the worst of these storms.
A raw image of Saturn taken by the Cassini spacecraft. Credit: NASA/JPL/Space Science Institute
Saturn: The Cassini spacecraft has been busily gazing at Saturn and its moons in the past week, including looking at temperatures in the atmosphere (specifically, in the upper troposphere and tropopause) in the gas giant. Just visible in this image is a huge hexagonal storm that scientists previously said acts somewhat like the Earth’s ozone hole.
A raw view of Titan taken by the Cassini spacecraft Aug. 13, 2014. Credit: NASA/JPL/Space Science Institute
Titan: Saturn’s largest moon — which contains organic compounds that could be precursors to life’s chemistry — is undergoing some changes as summer approaches. A few days ago, scientists noted that clouds are starting to form in Titan’s northern hemisphere. While they’re not sure yet if it will herald summer, scientists added that the lack of clouds before that defied models.
A close-up view of Comet 67P/Churyumov–Gerasimenko taken by the Rosetta spacecraft on Aug. 7, 2014. Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA
Comet 67P/Churyumov–Gerasimenko: The Rosetta spacecraft just arrived at this comet on Aug. 6, and has been sending back a few images of this small body that is speeding towards the Sun. You may recognize this particular image as part of the basis for a 3-D image that was released yesterday. Meanwhile, team members are examining dust production of the comet, which has already started as it heads to its closest Sun approach (between Earth and Mars) in about a year.
