Above ground and underground Martian drainages

Overview map

Cool image time! Today we are going to zoom into our cool image. The overview map to the right provides us the context. Our target is the small white rectangle inside the small box just below the north rim of 185-mile-wide Newton Crater, located 200 to 800 miles from the southwest edge of the lava plains dubbed Daedalia Planum that flowed down from Mars’s biggest volcanoes.

Newton Crater has a number of interesting features. Only two weeks ago I featured 4-mile-wide Avire Crater in Newton’s western quadrant, long known to have many gullies on its interior slopes as well as glacier features on its floor. Scientists have been monitoring those gullies now for more than a decade to see if they change seasonally, in a attempt to figure out their cause.

Today’s cool image looks at the very intriguing meandering canyons that appear to flow south from Newton’s north rim.
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Gullies and glaciers in a crater on Mars

The gullies and glaciers in Avire Crater
Click for full image.

Cool image time! The photo to the right, rotated, cropped, and reduced to post here, was taken on July 10, 2022 by the high resolution camera on Mars Reconnaissance Orbiter (MRO). It shows the floor of 4-mile-wide Avire Crater, located at about 41 degrees south latitude inside the much larger 185-mile wide Newton Crater.

This picture was taken as part of a long term monitoring program of the many gullies that flow down the slopes of the crater’s interior rim. In fact, the gullies of this crater have so interested scientists that one even proposed [pdf] this location as a potential future rover landing site.

Avire Crater, a small … gullied crater within Newton Crater, provides many aspects ideal to a future rover mission. It has been previously hypothesized to be the location of a former paleolake with multiple episodes of ponding and deposition. Gullies occur almost continuously on the southwest wall clockwise to the northeastern wall. Dark-toned dunes are present in the northern portion of the crater, in some places obscuring gullies while cut by gullies in others. No changes in the extent or appearance of the dunes have been observed since they were first imaged … in January of 2000. The dunes lack superimposed craters, indicating that the gullies that cut through them are geologically very youthful. Layered lobate features are present at the base of the gullies on the northern wall, seen in many other craters on Mars (not always in association with gullies), which have been suggested to have formed as terminal moraines of ice-rich flows; in Avire, these features have also been suggested to be paleolake deposits. The crater floor is obscured by mid-latitude “fill” material, hypothesized to be partially comprised of ice based on morphologic evidence that the material has been partially removed.

As gullies, dunes, and “fill” material occur in many places on Mars, a single rover mission to a site containing these features would provide valuable information applicable to thousands of other locations across the planet.

The curved ridgeline in the crater floor is thought to be a moraine. The “fill” material to the south is essentially glacial in nature. Both, as well as the gullies, appear to have been shaped either a paleolake that once existed in the crater or by cyclical glacier activity. By going to this one crater, scientists could study all these different geological features at one time.
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More evidence that there are active flows of water on Mars

flow features on Mars

More evidence that there are active flows of water on Mars.

Dark, finger-like features appear and extend down some Martian slopes during late spring through summer, fade in winter, and return during the next spring. Repeated observations have tracked the seasonal changes in these recurring features on several steep slopes in the middle latitudes of Mars’ southern hemisphere.

Though there are a number of unsolved issues about these features, the best explanation appears to be a liquid brine.

Saltiness lowers the freezing temperature of water. Sites with active flows get warm enough, even in the shallow subsurface, to sustain liquid water that is about as salty as Earth’s oceans, while pure water would freeze at the observed temperatures.

Go here to see the full image.