ESA Mars Express: Winter in Hooke crater in Argyre basin

Perspective view of Hooke crater in Argyre basin taken by the High Resolution Stereo Camera (HRSC) on ESA’s Mars Express. 

Credit: ESA /DLR

Over billions of years, the southern uplands of Mars have been pockmarked by numerous impact features, which are often so closely packed that they overlap.

One such feature is Hooke crater, shown in this frost-tinged scene, imaged by ESA’s Mars Express during winter in the southern hemisphere.

Hooke crater. Credit: ESA

Hooke crater is located near the northern edge of the 1800 km-wide Argyre basin, one of the most impressive impact structures on Mars, excavated in a giant collision about 4 billion years ago.

Sitting in a flat part of the basin known as Argyre Planitia, Hooke crater has a diameter of 138 km and a maximum depth of about 2.4 km.

It is named after the English physicist and astronomer Robert Hooke (1635–1703).

Hooke crater comprises two different impact structures, with a smaller impactor blasting a depression off-centre in the floor of a larger, pre-existing crater.

High Resolution Stereo Camera (HRSC)

The newer crater in the centre is filled with a large mound topped by a dark dune field. The mound appears to be composed of layered material, possibly alternating sheets of sand and frost.

Dark dunes also spread southwards (to the left in the topographic, main colour and 3D images) from the smaller crater, partially covering the floor of the main crater.

The local topography modifies the airflow, serving as a sand trap for the wind-blown sediments.

Hooke crater topography. Credit: ESA

In these images, much of the low-lying region to the south, as well as the central mound inside Hooke crater, is covered with a thin, white coating of carbon dioxide frost.

At higher elevations and on north-facing crater walls, the frost is largely absent and appears only in areas shaded from direct sunlight by the walls of smaller craters.

Outside the crater, there are a number of linear features visible on the floor of Argyre Planitia, on the south (left) side of the topographic, main colour and 3D images.

These are examples of ‘yardangs’, rocky ridges that have been shaped by prolonged wind erosion.

Most of the yardangs are oriented towards Hooke crater, indicating the prevailing wind direction.

An artist view of the HRSC on ESA Mars Express scanning the Mars mesas. 

Credit: ESA /DLR

Also visible on the floor of the Argyre basin are small areas of chaotic terrain, which resemble depressions containing flat-topped mesas, buttes and hills.

In the topographic, main colour and 3D images, one of these regions can be seen at the top edge, about a third of the way from the left, and another in the lower middle part, down from the left-most edge of the crater.

Chaotic terrains like these are thought to have been created when large-scale melting of ground ice caused the ground to collapse.

Where the terrain has not collapsed completely, the larger mesas may still contain substantial water ice.

NASA's Aqua Sees Massive US Winter Storm

On January 2, 2014, NASA’s Aqua satellite passed over the United States multiple times, allowing the Moderate Resolution Imaging Spectroradiometer (MODIS) on board to capture this true-colour image of a massive winter storm moving up the eastern seaboard. 

Another image taken the same day by the GOES-13 satellite shows moist air from the Gulf of Mexico and cold air from Canada moving across the U.S. (Shown below)

Very cold temperatures and dangerous wind chills are moving in behind the system. 

The next storm is forming, and will bring blizzard conditions to the northern Plains Friday Night into Saturday. 

Extreme wind chills to -55 F are possible in the northern Plains this weekend. 

Credit: NASA/NOAA

Mars Rover Opportunity Reaches Campsite for Martian Winter

NASA's Opportunity Mars rover used its navigation camera to record this image of the northern end of "Solander Point," a raised section of the western rim of Endeavour Crater, on Aug. 8, 2013.

Credit: NASA/JPL-Caltech

NASA's long-lived Opportunity Mars rover has reached the site where it will wait out its sixth Red Planet winter.

Opportunity — which touched down on Mars in January 2004 just after its twin, Spirit, arrived on the planet — is studying rocks at the foot of a location called Solander Point, whose north-facing slope will allow the robot to tilt its solar panels toward the sun during the coming southern Martian winter.

"We made it," Opportunity project scientist Matt Golombek, of NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a statement. "The drives went well, and Opportunity is right next to Solander Point."

"We know we could be on that north-facing slope with a one-day drive, but we don't need to go there yet. We have time to investigate the contact between the two geological units around the base of Solander Point."



One of those two units preserves evidence of long-ago contact with acidic water, while the other one is older and may contain minerals that formed in more neutral and benign liquid water, researchers said.

The Opportunity rover arrived at the base of Solander Point in the first few days of August, after a three-month, 1.5-mile (2.4 kilometers) journey from a spot called Cape York.

Both Solander Point and Cape York sit along the rim of the 14-mile-wide (22 km) Endeavour Crater, which Opportunity reached in August 2011.

The days are getting shorter in Mars' southern hemisphere, and the amount of sunlight available to the solar-powered Opportunity will reach a minimum in mid-February 2014 (the southern winter solstice occurs on Feb. 14).

NASA Cassini Image: Saturn's Southern Winter Approaches

Credit: NASA /JPL-Caltech /Space Science Institute

The shadows of Saturn's rings slide farther southward as Saturn approaches southern winter (or northern summer). 

Saturn now lies almost exactly halfway between its equinox (August 2009) and southern winter solstice (in May 2017). 

This view centers on an area at 22 degrees south latitude on Saturn. 

Cassini spacecraft took the image with its wide-angle camera on May 6, 2013.

NASA Cassini: Seasonal changes on Saturn

A blue hue appears in Saturn's southern hemisphere as winter approaches. Credit: NASA/JPL-Caltech/SSI

Three of the most recent images show Saturn’s largest moon, Titan, and the recently discovered vortex in the atmosphere at the south pole.

The visible light cameras on Cassini have been monitoring a strange yellow haze in the detached haze layer at Titan’s south pole since 27 March.

The visual and infrared spectrometers then detected clouds building up in the region on 22 May.

When Cassini flew by Titan on June 27, 2012, it was found that the vortex is spinning faster than the moon itself is rotating.

The views of the vortex are only possible because Cassini is on a new orbit that is tilted, which enables it to get a better look at the polar regions of both Saturn and its moons.

"Cassini has been in orbit now for the last eight years, and despite the fact that we can't know exactly what the next five years will show us, we can be certain that whatever it is will be wondrous," explains Carolyn Porco.

The south polar vortex is visible in this image. Credit: NASA/JPL-Caltech/SSI 

Cassini is currently in its second mission extension, which has been called the Solstice Mission, and monitoring the seasonal changes on the ringed planet is one of the main objectives at the moment.

"It is so fantastic to experience, through the instruments of Cassini, seasonal changes in the Saturn system," said depute project scientist Amanda Hendrix.

"Some of the changes we see in the data are completely unexpected, while some occur like clockwork on a seasonal timescale. It's an exciting time to be at Saturn."