Saturn Straw

This Cassini image features a density wave in Saturn’s A ring (at left) that lies around 134,500 km from Saturn. Density waves are accumulations of particles at certain distances from the planet. This feature is filled with clumpy perturbations, which researchers informally refer to as “straw.” The wave itself is created by the gravity of the moons Janus and Epimetheus, which share the same orbit around Saturn. Elsewhere, the scene is dominated by “wakes” from a recent pass of the ring moon Pan.

Two versions of this image are available. This is a lightly processed version, with minimal enhancement, preserving all original details present in the image. The other version (Figure 1) has been processed to remove the small bright blemishes caused by cosmic rays and charged particle radiation near the planet — a more aesthetically pleasing image, but with a slight softening of the finest details.

The image was taken in visible light with the Cassini spacecraft wide-angle camera on Dec. 18, 2016. The view was obtained at a distance of approximately 34,000 miles (56,000 kilometers) from the rings and looks toward the unilluminated side of the rings. Image scale is about a quarter-mile (340 meters) 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.

Credit: NASA/JPL-Caltech/Space Science Institute

Keck’s Vortex Coronagraph

The new addition to the Keck telescope, the vortex coronagraph, has returned some fantastic early results – a brown dwarf orbiting a larger star!

The brown dwarf named HIP79124 B is 23 astronomical units from the larger star, so if that were in our solar system it would be more or less half way between Uranus and Neptune.

Read the press release here.

Credit: NASA/JPL-Caltech

Martian Mud Cracks?

Yet more evidence of water on Mars. Would we be able to detect any traces of life if it existed after a couple thousand-million years or so?

From NASA:

The network of cracks in this Martian rock slab called “Old Soaker” may have formed from the drying of a mud layer more than 3 billion years ago. The view spans about 4 feet (1.2 meters) left-to-right and combines three images taken by the Mars Hand Lens Imager (MAHLI) camera on the arm of NASA’s Curiosity Mars rover.

Mud cracks would be evidence of a time when dry intervals interrupted wetter periods that supported lakes in the area. Curiosity has found evidence of ancient lakes in older, lower-lying rock layers and also in younger mudstone that is above Old Soaker.

MAHLI was positioned about 3 feet (90 centimeters) above the surface when it took the component images on Dec. 31, 2016, during the 1,566th Martian day, or sol, of Curiosity’s work on Mars. This observation was planned as part of assessing a hypothesis that the target preserves evidence of drying mud. The location is within an exposure of Murray formation mudstone on lower Mount Sharp inside Gale Crater.

The slab bears a network of four- and five-sided polygons about half an inch to 1 inch (1 to 2 centimeters) across, which matches the pattern commonly formed when a thin layer of mud dries. Some edges of the polygons are ridges of material the same color as the surrounding rock. This could result from a three-step process after cracks form due to drying: Wind-blown sediments accumulate in the open cracks. Later, these sediments and the dried mud become rock under the pressure of multiple younger layers that accumulate on top of them. Most recently, after the overlying layers were eroded away by wind, the vein-filling material resists erosion better than the once-muddy material, so the pattern that began as cracks appears as ridges.

Note that some of the cracks contain material much brighter than the surrounding rock. These are mineral veins. Curiosity has found such bright veins of calcium sulfate in many rock layers the rover has investigated. These veins form from circulation of mineral-laden groundwater through underground cracks. Rover-team scientists suggest that a likely scenario for the history of Old Soaker is more than one generation of fracturing: mud cracks first, with sediment accumulating in them, then a later episode of underground fracturing and vein forming.

The target rock’s name comes from the name of an island off the coast of Maine. The names informally assigned by the rover team to features in the area of lower Mount Sharp that includes this slab are from a list of islands, hills and other sites in or near Maine’s Bar Harbor.

Malin Space Science Systems, San Diego, built and operates MAHLI. NASA’s Jet Propulsion Laboratory, a division of the Caltech in Pasadena, California, manages the Mars Science Laboratory Project for the NASA Science Mission Directorate, Washington, and built the project’s Curiosity rover. More information about Curiosity is online at http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/.

Credit: NASA/JPL-Caltech/MSSS

The Little Red Spot

Below is a Juno spacecraft image of the northern part of Jupiter at just 16,000 km / 10,300 miles. The image was taken during the 11 December 2016 fly-by.

Juno is on a 53.4 day orbit and that makes the next close approach or perijove in just a few days on 02 February 2017.

All raw Juno images can be seen at the JunoCam site and the public is encouraged to download and process the images and even share your images back.

This particular image is from NASA/JPL-Caltech/SwRI/MSSS/Gerald Eichstaedt/John Rogers. Very nice work!

Here’s the NASA caption:
This stunning view of the high north temperate latitudes fortuitously shows NN-LRS-1, a giant storm known as a Little Red Spot (lower left). This storm is the third largest anticyclonic reddish oval on the planet, which Earth-based observers have tracked for the last 23 years. An anticyclone is a weather phenomenon with large-scale circulation of winds around a central region of high atmospheric pressure. They rotate clockwise in the northern hemisphere, and counterclockwise in the southern hemisphere. This Little Red Spot shows very little color, just a pale brown smudge in the center. The color is very similar to the surroundings, making it difficult to see as it blends in with the clouds nearby. Citizen scientists Gerald Eichstaedt and John Rogers processed the image and drafted the caption.

Tribute to Apollo 1

NASA opened a new tribute to the crew, astronauts Gus Grissom, Ed White II and Roger Chaffee , of Apollo 1 who perished in a fire at the launch pad on Jan. 27, 1967, during training for the mission.

Add this to your tour of KSC when you go!

Hubble Used to Update Hubble Constant

Pretty cool.  The Hubble  Space Telescope have made an independent measurement of how fast the Universe is expanding. The newly measured expansion rate for the local Universe is very consistent with earlier findings.

Credits: NASA, ESA, Suyu (Max Planck Institute for Astrophysics), Auger (University of Cambridge)

Did I say there was cosmic (gravitational) lensing involved?  Here’s what NASA  has to say:

This research was presented in a series of papers to appear in the Monthly Notices of the Royal Astronomical Society.

The new measurement is completely independent of — but in excellent agreement with — other measurements of the Hubble constant in the local Universe that used Cepheid variable stars and supernovae as points of reference [heic1611].

However, the value measured by Suyu and her team, as well as those measured using Cepheids and supernovae, are different from the measurement made by the ESA Planck satellite. But there is an important distinction — Planck measured the Hubble constant for the early Universe by observing the cosmic microwave background.

While the value for the Hubble constant determined by Planck fits with our current understanding of the cosmos, the values obtained by the different groups of astronomers for the local Universe are in disagreement with our accepted theoretical model of the Universe. “The expansion rate of the Universe is now starting to be measured in different ways with such high precision that actual discrepancies may possibly point towards new physics beyond our current knowledge of the Universe,” elaborates Suyu.

The targets of the study were massive galaxies positioned between Earth and very distant quasars — incredibly luminous galaxy cores. The light from the more distant quasars is bent around the huge masses of the galaxies as a result of strong gravitational lensing. This creates multiple images of the background quasar, some smeared into extended arcs.

Because galaxies do not create perfectly spherical distortions in the fabric of space and the lensing galaxies and quasars are not perfectly aligned, the light from the different images of the background quasar follows paths which have slightly different lengths. Since the brightness of quasars changes over time, astronomers can see the different images flicker at different times, the delays between them depending on the lengths of the paths the light has taken. These delays are directly related to the value of the Hubble constant. “Our method is the most simple and direct way to measure the Hubble constant as it only uses geometry and General Relativity, no other assumptions,” explains co-lead Frédéric Courbin from the Laboratory of Astrophysics, Lastro (EPFL), Switzerland.

Using the accurate measurements of the time delays between the multiple images, as well as computer models, has allowed the team to determine the Hubble constant to an impressively high precision: 3.8 percent. “An accurate measurement of the Hubble constant is one of the most sought-after prizes in cosmological research today,” highlights team member Vivien Bonvin, from EPFL, Switzerland. And Suyu adds: “The Hubble constant is crucial for modern astronomy as it can help to confirm or refute whether our picture of the Universe — composed of dark energy, dark matter and normal matter — is actually correct, or if we are missing something fundamental.”

The Hubble Space Telescope is a project of international cooperation between ESA and NASA.

GOES 16

This view of the Earth and Moon comes from the American weather satellite GOES-16. This image comes from the Advanced Baseline Imager (ABI) instrument, built by Harris Corporation and can provide an image every 15 minutes.

The (US) National Oceanic and Atmospheric Administration (NOAA) satellite will have company soon as the GOES-17 is in the works.

The NOAA press release – with more images, is located here.

Credit: NOAA

Tethys and Odysseus

Each time we get a picture of a moon from Cassini it’s hard to know if it will be the last, especially one that has such a good angle on a magnificent landmark like the crater Odysseus.

Original caption from the Cassini team:

Tethys, one of Saturn’s larger icy moons, vaguely resembles an eyeball staring off into space in this view from NASA’s Cassini spacecraft. The resemblance is due to the enormous crater, Odysseus, and its complex of central peaks.

Like any solar system moon, Tethys (660 miles or 1,062 kilometers across) has suffered many impacts. These impacts are a prime shaper of the appearance of a moon’s surface , especially when the moon has no active geological processes. In this case, a large impact not only created a crater known as Odysseus, but the rebound of the impact caused the mountainous peaks, named Scheria Montes, to form in the center of the crater.

This view looks toward the leading side of Tethys. North on Tethys is up and rotated 1 degree to the left. The image was taken in green light with the Cassini spacecraft narrow-angle camera on Nov. 10, 2016.

The view was acquired at a distance of approximately 228,000 miles (367,000 kilometers) from Tethys. Image scale is 1.2 miles (2 kilometers) per pixel.

Credit: NASA/JPL-Caltech/Space Science Institute

Martian Bedrock

Roadside bedrock outcrops are all too familiar for many who have taken a long road trip through mountainous areas on Earth. Martian craters provide what tectonic mountain building and man’s TNT cannot: crater-exposed bedrock outcrops.

Although crater and valley walls offer us roadside-like outcrops from just below the Martian surface, their geometry is not always conducive to orbital views. On the other hand, a crater central peak — a collection of mountainous rocks that have been brought up from depth, but also rotated and jumbled during the cratering process — produce some of the most spectacular views of bedrock from orbit.

This color composite cutout shows an example of such bedrock that may originate from as deep as 2 miles beneath the surface. The bedrock at this scale is does not appear to be layered or made up of grains, but has a massive appearance riddled with cross-cutting fractures, some of which have been filled by dark materials and rock fragments (impact melt and breccias) generated by the impact event. A close inspection of the image shows that these light-toned bedrock blocks are partially to fully covered by sand dunes and coated with impact melt bearing breccia flows.

This is a stereo pair with ESP_012367_1695.

Thanks to: The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA’s Science Mission Directorate, Washington.