For #SaturnSaturday, here’s our #GrandFinale by the numbers. More: go.nasa.gov/1Up1oba
Calm lakes on Titan could mean smooth landing for future space probeshttps://phys.org/news/2017-07-calm-lakes-titan-smooth-future.amp
CassiniSaturn Verified account @CassiniSaturn 3m3 minutes agoWe captured this unprocessed close-up of Saturn’s rings during the latest ring crossing on 7/12. See more raw images https://go.nasa.gov/2guHnlH
Just started #GrandFinale orbit 15. We'll be watching for clouds on Titan, listening for lightning on Saturn. More: https://saturn.jpl.nasa.gov/mission/grand-finale/grand-finale-orbit-guide/
NEWS & FEATURES | July 24, 2017Saturn Surprises As Cassini Continues its Grand FinaleAs NASA's Cassini spacecraft makes its unprecedented series of weekly dives between Saturn and its rings, scientists are finding -- so far -- that the planet's magnetic field has no discernable tilt. This surprising observation, which means the true length of Saturn's day is still unknown, is just one of several early insights from the final phase of Cassini's mission, known as the Grand Finale.Other recent science highlights include promising hints about the structure and composition of the icy rings, along with high-resolution images of the rings and Saturn's atmosphere.Cassini is now in the 15th of 22 weekly orbits that pass through the narrow gap between Saturn and its rings. The spacecraft began its finale on April 26 and will continue its dives until Sept. 15, when it will make a mission-ending plunge into Saturn's atmosphere."Cassini is performing beautifully in the final leg of its long journey," said Cassini Project Manager Earl Maize at NASA's Jet Propulsion Laboratory, Pasadena, California. "Its observations continue to surprise and delight as we squeeze out every last bit of science that we can get."Cassini scientists are thrilled as well -- and surprised in some cases -- with the observations being made by the spacecraft in the finale. "The data we are seeing from Cassini's Grand Finale are every bit as exciting as we hoped, although we are still deep in the process of working out what they are telling us about Saturn and its rings," said Cassini Project Scientist Linda Spilker at JPL.Early Magnetic Field AnalysisBased on data collected by Cassini's magnetometer instrument, Saturn's magnetic field appears to be surprisingly well-aligned with the planet's rotation axis. The tilt is much smaller than 0.06 degrees -- which is the lower limit the spacecraft's magnetometer data placed on the value prior to the start of the Grand Finale.This observation is at odds with scientists' theoretical understanding of how magnetic fields are generated. Planetary magnetic fields are understood to require some degree of tilt to sustain currents flowing through the liquid metal deep inside the planets (in Saturn's case, thought to be liquid metallic hydrogen). With no tilt, the currents would eventually subside and the field would disappear.Any tilt to the magnetic field would make the daily wobble of the planet's deep interior observable, thus revealing the true length of Saturn's day, which has so far proven elusive."The tilt seems to be much smaller than we had previously estimated and quite challenging to explain," said Michele Dougherty, Cassini magnetometer investigation lead at Imperial College, London. "We have not been able to resolve the length of day at Saturn so far, but we're still working on it."The lack of a tilt may eventually be rectified with further data. Dougherty and her team believe some aspect of the planet's deep atmosphere might be masking the true internal magnetic field. The team will continue to collect and analyze data for the remainder of the mission, including during the final plunge into Saturn.The magnetometer data will also be evaluated in concert with Cassini's measurements of Saturn's gravity field collected during the Grand Finale. Early analysis of the gravity data collected so far shows discrepancies compared with parts of the leading models of Saturn's interior, suggesting something unexpected about the planet's structure is awaiting discovery.Sampling SaturnIn addition to its investigation of the planet's interior, Cassini has now obtained the first-ever samples of the planet's atmosphere and main rings, which promise new insights about their composition and structure. The spacecraft's cosmic dust analyzer (CDA) instrument has collected many nanometer-size ring particles while flying through the planet-ring gap, while its ion and neutral mass spectrometer (INMS) has sniffed the outermost atmosphere, called the exosphere.During Cassini's first dive through the gap on April 26, the spacecraft was oriented so its large, saucer-shaped antenna would act as a shield against oncoming ring particles that might cause damage. While at first it appeared that there were essentially no particles in the gap, scientists later determined the particles there are very small and could be detected using the CDA instrument.The cosmic dust analyzer was later allowed to peek out from behind the antenna during Cassini's third of four passes through the innermost of Saturn's main rings, the D ring, on June 29. During Cassini's first two passes through the inner D ring, the particle environment there was found to be benign. This prompted mission controllers to relax the shielding requirement for one orbit, in hopes of capturing ring particles there using CDA. As the spacecraft passed through the ring, the CDA instrument successfully captured some of the tiniest particles there, which the team expects will provide significant information about their composition.During the spacecraft's final five orbits, as well as it final plunge, the INMS instrument will obtain samples deeper down in the atmosphere. Cassini will skim through the outer atmosphere during these passes, and INMS is expected to send particularly important data on the composition of Saturn's atmosphere during the final plunge.Amazing ImagesNot to be outdone, Cassini's imaging cameras have been hard at work, returning some of the highest-resolution views of the rings and planet they have ever obtained. For example, close-up views of Saturn's C ring -- which features mysterious bright bands called plateaus -- reveal surprisingly different textures in neighboring sections of the ring. The plateaus appear to have a streaky texture, whereas adjacent regions appear clumpy or have no obvious structure at all. Ring scientists believe the new level of detail may shed light on why the plateaus are there, and what is different about the particles in them.On two of Cassini's close passes over Saturn, on April 26 and June 29, the cameras captured ultra-close views of the cloudscape racing past, showing the planet from closer than ever before. Imaging scientists have combined images from these dives into two new image mosaics and a movie sequence. (Specifically, the previously released April 26 movie was updated to greatly enhance its contrast and sharpness.)Launched in 1997, Cassini has orbited Saturn since arriving in 2004 for an up-close study of the planet, its rings and moons, and its vast magnetosphere. Cassini has made numerous dramatic discoveries, including a global ocean with indications of hydrothermal activity within the moon Enceladus, and liquid methane seas on another moon, Titan.The Cassini-Huygens mission is a cooperative project of NASA, ESA (European Space Agency) and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the mission for NASA's Science Mission Directorate, Washington. JPL designed, developed and assembled the Cassini orbiter.More information about the Cassini mission:https://www.nasa.gov/cassinihttps://saturn.jpl.nasa.gov
This false-color view from NASA's Cassini spacecraft gazes toward the rings beyond Saturn's sunlit horizon, where a thin haze can be seen along the limb. Image credit: NASA/JPL-Caltech/Space Science Institute
This colorful spectrogram represents data collected by Cassini's Radio and Plasma Wave Science instrument as it crossed through Saturn's D ring on May 28, 2017. Image Credit: NASA/JPL-Caltech/University of Iowa
This mosaic combines views captured by Cassini as it made the first dive of the mission's Grand Finale on April 26, 2017, and shows details in bands and swirls in the atmosphere. Image Credit: NASA/JPL-Caltech/SSI/Hampton University
Enceladus’ intriguing south-polar jets are viewed by the Cassini probe from afar, backlit by sunlight while the moon itself glows softly in reflected Saturn-shine.Observations of the jets taken from various viewing geometries provide different insights into these remarkable features. Cassini has gathered a wealth of information in the hopes of unraveling the mysteries of the subsurface ocean that lurks beneath the moon’s icy crust.
The international Cassini-Huygens mission has made a surprising detection of a molecule that is instrumental in the production of complex organics within the hazy atmosphere of Saturn's moon Titan.
Titan boasts a thick nitrogen and methane atmosphere with some of the most complex chemistry seen in the Solar System. It is even thought to mimic the atmosphere of early Earth, before the build-up of oxygen. As such, Titan can be seen as a planet-scale laboratory that can be studied to understand the chemical reactions that may have led to life on Earth, and that could be occurring on planets around other stars.In Titan's upper atmosphere, nitrogen and methane are exposed to energy from sunlight and energetic particles in Saturn's magnetosphere. These energy sources drive reactions involving nitrogen, hydrogen and carbon, which lead to more complicated prebiotic compounds.These large molecules drift down towards the lower atmosphere, forming a thick haze of organic aerosols, and are thought to eventually reach the surface. But the process by which simple molecules in the upper atmosphere are transformed into the complex organic haze at lower altitudes is complicated and difficult to determine.One surprising outcome of the Cassini mission was the discovery of a particular type of negatively charged molecule at Titan. Negatively charged species – or 'anions' – were not something scientists expected to find, because they are highly reactive and should not last long in Titan's atmosphere before combining with other materials. Their detection is completely reshaping current understanding of the hazy moon's atmosphere.In a new study published in The Astrophysical Journal Letters, scientists identified some of the negatively charged species as what are known as 'carbon chain anions'. These linear molecules are understood to be building blocks towards more complex molecules, and may have acted as the basis for the earliest forms of life on Earth.Chemistry in Titan's atmosphere.The detections were made using Cassini's plasma spectrometer, called CAPS, as Cassini flew through Titan's upper atmosphere, 950–1300 km above the surface. Interestingly, the data showed that the carbon chains became depleted closer to the moon, while precursors to larger aerosol molecules underwent rapid growth, suggesting a close relationship between the two, with the chains 'seeding' the larger molecules."We have made the first unambiguous identification of carbon chain anions in a planet-like atmosphere, which we believe are a vital stepping-stone in the production line of growing bigger, and more complex organic molecules, such as the moon's large haze particles," says Ravi Desai of University College London and lead author of the study."This is a known process in the interstellar medium, but now we've seen it in a completely different environment, meaning it could represent a universal process for producing complex organic molecules."The question is, could it also be happening within other nitrogen-methane atmospheres like at Pluto or Triton, or at exoplanets with similar properties?""The prospect of a universal pathway towards the ingredients for life has implications for what we should look for in the search for life in the Universe," says co-author Andrew Coates, also from UCL, and co-investigator of CAPS."Titan presents a local example of exciting and exotic chemistry, from which we have much to learn."Cassini's 13-year odyssey in the Saturnian system will soon draw to a close, but future missions, such as the international James Webb Space Telescope and ESA's PLATO exoplanet mission are being equipped to look for this process not only in our own Solar System but elsewhere. Advanced ground-based facilities such as ALMA could also enable follow-up observations of this process at work in Titan's atmosphere, from Earth."These inspiring results from Cassini show the importance of tracing the journey from small to large chemical species in order to understand how complex organic molecules are produced in an early Earth-like atmosphere," adds Nicolas Altobelli, ESA's Cassini-Huygens Project Scientist."While we haven't detected life itself, finding complex organics not just at Titan, but also in comets and throughout the interstellar medium, we are certainly coming close to finding its precursors."
Cassini will pass through Saturn’s upper atmosphere during the final five orbits of the mission, before making a fateful plunge into Saturn on Sept. 15, 2017. The region through which the spacecraft will fly on those last orbits is well above the haze seen here, which is in Saturn’s stratosphere. In fact, even when Cassini plunges toward Saturn to meet its fate, contact with the spacecraft is expected to be lost before it reaches the depth of this haze.This view is a false-color composite made using images taken in red, green and ultraviolet spectral filters. The images were obtained using the Cassini spacecraft narrow-angle camera on July 16, 2017, at a distance of about 777,000 miles (1.25 million kilometers) from Saturn. Image scale is about 4 miles (7 kilometers) per pixel on Saturn.
To add to the conversation about the latest discovery/paper:Carbon Chain Anions and the Growth of Complex Organic Molecules in Titan's Ionospherehttp://iopscience.iop.org/article/10.3847/2041-8213/aa7851Saturn’s moon Titan may harbour simple life forms – and reveal how organisms first formed on Earthhttps://theconversation.com/saturns-moon-titan-may-harbour-simple-life-forms-and-reveal-how-organisms-first-formed-on-earth-81527
I guess if the Huygens probe had a gas chromatograph on board then most of these questions would probably have already been answered one way or the other.
Published on 11 Aug 2017Saturn’s giant, hazy moon Titan has been essential to NASA’s Cassini mission during its 13 thrilling years of exploration there. Cassini and the European Huygens probe have revealed a fascinating world of lakes and seas, great swaths of dunes, and a complex atmosphere with weather – with intriguing similarities to Earth. Titan has also been an engine for the mission, providing gravity assists that propelled the spacecraft on its adventures around the ringed planet. For more about the Cassini-Huygens mission, visit https://saturn.jpl.nasa.gov
Never a truer comment made under that conversation article.QuoteI guess if the Huygens probe had a gas chromatograph on board then most of these questions would probably have already been answered one way or the other.