NASA ESA Cassini Image: Saturn's Vortex and rings

Credit: NASA/JPL-Caltech/Space Science Institute

The Cassini spacecraft captures three magnificent sights at once: Saturn's north polar vortex and hexagon along with its expansive rings.

The hexagon, which is wider than two Earths, owes its appearance to the jet stream that forms its perimeter.

The jet stream forms a six-lobed, stationary wave which wraps around the north polar regions at a latitude of roughly 77 degrees North.

This view looks toward the sunlit side of the rings from about 37 degrees above the ringplane.

The image was taken with the Cassini spacecraft wide-angle camera on April 2, 2014 using a spectral filter which preferentially admits wavelengths of near-infrared light centered at 752 nanometers.

The view was obtained at a distance of approximately 1.4 million miles (2.2 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 43 degrees. Image scale is 81 miles (131 kilometers) per pixel.

The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency.

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, Colo.

For more information about the Cassini-Huygens mission or the Cassini imaging team homepage.

Superfluid Helium: Hunt for an 'unidentified electron object'

This image shows vortex rings as the result of vortex multiplication in a quantum fluid. Some electrons are free, some got trapped by one or more vortices. 

Credit: Gleb and Sofia Berloff, ISM

New research sheds light on the nature of 'unidentified electron objects'—a mysterious class of objects that exists in superfluid helium at low temperature.

Researchers have developed a new mathematical framework capable of describing motions in superfluids – low temperature fluids that exhibit classical as well as quantum behaviour.

The framework was used to lift the veil of mystery surrounding strange objects in superfluid helium (detected ten years ago at Brown University).

The study, conducted by an international collaboration of researchers from the UK, Russia and France is published today in the journal Proceedings of National Academy of Sciences (PNAS).

The quantum nature of superfluids manifests itself in the form of quantized vortices, tiny twisters, with the core sizes of the order of an Angstrom (0.1nm – approximately the diameter of an atom) that move through fluid severing and coalescing, forming bundles and tangles.

To make these processes even more intricate and distinct from motions in usual classical fluids, these tiny twisters live on the background consisting of a mixture of viscous and inviscid fluid components that constitute superfluid.

The mathematical modelling of such complex systems that involve a range of scales is a notoriously difficult problem.

Natalia Berloff

The international team of researchers; Natalia Berloff of the University of Cambridge and the Russian Skolkovo Institute of Science and Technology, Marc Brachet of Université Pierre-et-Marie-Curie and Nick Proukakis of Joint Quantum Centre Durham came up with a novel framework for achieving this task.

The team applied their method to elucidate an intriguing phenomenon in liquid helium research.

Electrons immersed in superfluid helium are useful experimental probes. As they move through superfluid they form soft bubbles of about 2 nm in diameter that get trapped by quantized vortices quite similar to how houses and cars become trapped and transported by a tornado.

A research team from Brown University led by Professor Humphrey Maris has studied the effect of oscillating pressures on electron bubbles.

As pressure decreases below the criticality, the bubble expands and explodes, reaching micron sizes, with the bubble trapped by a vortex exploding at a pressure larger than that for the free bubble.

Maris' team also discovered another class of object that existed at very low temperatures only and exploded at even larger pressures. They termed these "unidentified electron objects".

More information: The paper 'Modeling quantum fluid dynamics at nonzero temperatures' was published today, 24 March 2014, in the journal Proceedings of the National Academy of Sciences (PNAS). www.pnas.org/cgi/doi/10.1073/pnas.1312549111

NASA: In the Vortex of Power

Image Credit: NASA

Bridget R. Caswell (Wyle Information Systems, LLC)

John Wargo, lead technician at NASA Glenn's Propulsion System Laboratory (PSL) is performing an inspection on the inlet ducting, upstream of the Honeywell ALF 502 engine that was recently used for the NASA Engine Icing Validation test.

This test allows engine manufacturers to simulate flying through the upper atmosphere where large amounts of icing particles can be ingested and cause flame outs or a loss of engine power on aircraft.

This test was the first of its kind in the world and was highly successful in validating PSL's new capability. No other engine test facility has this capability.

John Wargo

Glenn is working with industry to address this aviation issue by establishing a capability that will allow engines to be operated at the same temperature and pressure conditions experienced in flight, with ice particles being ingested into full scale engines to simulate flight through a deep convective cloud.

The information gained through performing these tests will also be used to establish test methods and techniques for the study of engine icing in new and existing commercial engines, and to develop data required for advanced computer codes that can be specifically applied to assess an engine's susceptibility to icing in terms of its safety, performance and operability.

NASA Cassini Image: Vortex at Titan's South Pole

A true colour image of Saturn's moon Titan, captured by NASA's Cassini spacecraft, shows a south polar vortex, or a mass of swirling gas, around the pole. 

The formation of the vortex at Titan's south pole may be related to the coming southern winter.

Picture: REUTERS/NASA/JPL-Caltech/Space Science Institute