All posts by Tom

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.

Sitting On The Edge

 

It looks like ESA astronaut Thomas Pesquet is dangling his feet into the void. Actually he was on a spacewalk and together with NASA astronaut Shane Kimbrough, he spent five hours and 58 minutes outside the Space Station to complete a battery upgrade to the outpost’s power system.

Thomas commented on this picture: “This is what a spacewalk is: 400 km of void under your feet”

Credit: ESA

Daphnis

Probably one of our last views of Daphnis from Cassini. The moon appears to be traveling towards the right in this image.

From Cassini:

The wavemaker moon, Daphnis, is featured in this view, taken as NASA’s Cassini spacecraft made one of its ring-grazing passes over the outer edges of Saturn’s rings on Jan. 16, 2017. This is the closest view of the small moon obtained yet.

Daphnis (5 miles or 8 kilometers across) orbits within the 42-kilometer (26-mile) wide Keeler Gap. Cassini’s viewing angle causes the gap to appear narrower than it actually is, due to foreshortening.

The little moon’s gravity raises waves in the edges of the gap in both the horizontal and vertical directions. Cassini was able to observe the vertical structures in 2009, around the time of Saturn’s equinox (see PIA11654).

Like a couple of Saturn’s other small ring moons, Atlas and Pan, Daphnis appears to have a narrow ridge around its equator and a fairly smooth mantle of material on its surface — likely an accumulation of fine particles from the rings. A few craters are obvious at this resolution. An additional ridge can be seen further north that runs parallel to the equatorial band.

Fine details in the rings are also on display in this image. In particular, a grainy texture is seen in several wide lanes which hints at structures where particles are clumping together. In comparison to the otherwise sharp edges of the Keeler Gap, the wave peak in the gap edge at left has a softened appearance. This is possibly due to the movement of fine ring particles being spread out into the gap following Daphnis’ last close approach to that edge on a previous orbit.

A faint, narrow tendril of ring material follows just behind Daphnis (to its left). This may have resulted from a moment when Daphnis drew a packet of material out of the ring, and now that packet is spreading itself out.

The image was taken in visible (green) light with the Cassini spacecraft narrow-angle camera. The view was acquired at a distance of approximately 17,000 miles (28,000 kilometers) from Daphnis and at a Sun-Daphnis-spacecraft, or phase, angle of 71 degrees. Image scale is 551 feet (168 meters) per pixel.

Credit: NASA/JPL-Caltech/Space Science Institute

ALMA and Solar Science

Global cooperation is the hallmark of ALMA and much of science for that matter. The ALMA Solar campaign is one of the most diverse, take a look below the fold at the end of the press release.

This image of an enormous sunspot was taken on 18 December 2015 with the Band 6 receiver at a wavelength of 1.25 millimeters.

ALMA Reveals Sun in New Light

New images from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal stunning details of our Sun, including the dark, contorted center of an evolving sunspot that is nearly twice the diameter of the Earth.

These images are part of the testing and verification campaign to make ALMA’s solar observing capabilities available to the international astronomical community.

Though designed principally to observe remarkably faint objects throughout the universe — such as distant galaxies and planet-forming disks around young stars – ALMA is also capable of studying objects in our own solar system, including planets, comets, and now the Sun.

During a 30-month period beginning in 2014, an international team of astronomers harnessed ALMA’s single-antenna and array capabilities to detect and image the millimeter-wavelength light emitted by the Sun’s chromosphere — the region that lies just above the photosphere, the visible surface of the Sun.

These new images demonstrate ALMA’s ability to study solar activity at longer wavelengths than observed with typical solar telescopes on Earth, and are an important expansion of the range of observations that can be used to probe the physics of our nearest star.

“We’re accustomed to seeing how our Sun appears in visible light, but that can only tell us so much about the dynamic surface and energetic atmosphere of our nearest star,” said Tim Bastian, an astronomer with the National Radio Astronomy Observatory in Charlottesville, Va. “To fully understand the Sun, we need to study it across the entire electromagnetic spectrum, including the millimeter and submillimeter portion that ALMA can observe.”

Since our Sun is many billions of times brighter than the faint objects ALMA typically observes, the solar commissioning team had to developed special procedures to enable ALMA to safely image the Sun.

The result of this work is a series of images that demonstrates ALMA’s unique vision and ability to study our Sun on multiple scales.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.

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Eugene Cernan 1934 – 2017

The last man to walk on the moon has died. Gene Cernan passed in a Houston Hospital 16 January 2017, he was 82 years-old.

The Houston Public Library Digital Archives.

170:41:00 Cernan: Bob, this is Gene, and I’m on the surface; and, as I take man’s last step from the surface, back home for some time to come – but we believe not too long into the future – I’d like to just (say) what I believe history will record. That America’s challenge of today has forged man’s destiny of tomorrow. And, as we leave the Moon at Taurus- Littrow, we leave as we came and, God willing, as we shall return, with peace and hope for all mankind. “Godspeed the crew of Apollo 17.” – EVA 3 Close-out

Godspeed to you Gene.

Space Weather Coming Our Way

Here comes an active region on the sun, But don’t worry, despite way you may hear on the internet, in the grand scheme of things this region is nothing to get too excited about. I’m sort of hoping this area gets busier as it rotates around to us.

Yes, I am in need, the need to see a decent aurora, it’s been too long! An no, you should not put much stock into the “doom and gloom” sites quick to predict our imminent demise. Yeah those sites might be kind of fun to listen to/read about but remember as with a lot of things these days, enjoy it all, but take everything with a grain of salt – we’ve lived with ol’ Sol for an awfully long time.

From NASA and the SDO:
Magnetic arcs of plasma that spiraled above two active regions held their shape fairly well over 18 hours (Jan. 11-12, 2017). The charged plasma is being controlled the magnetic field lines of the active regions. The field lines become clearly visible when viewed in this wavelength of extreme ultraviolet light. Often the arches bend and twist more dynamically than the relatively stable ones seen here.

Credit: Solar Dynamics Observatory, NASA.

SpaceX Launch/Landing Replay

Here is the SpaceX launch of the Iridium satellite replay. This is the entire Hosted Webcast; launch is 20 minutes into the video if you want to skip ahead.

Iridium Communications is reporting all 10 satellites were successfully deployed and will be in a testing phase for a few weeks.

On a sad note, this marks the end of Iridium flares, the beginning of the end anyway.  If you’ve never seen an Iridium flare you still can, but better probably to do so sooner rather than later.

Try either (or both) of the following links to get viewing information for Iridium flares or other visible satellites (like the ISS or Hubble):

Heavens Above
or
SpaceWeather.com
 

SpaceX video