Please consider donating to Behind the Black, by giving either a one-time contribution or a regular subscription, as outlined in the tip jar below. Your support will allow me to continue covering science and culture as I have for the past twenty years, independent and free from any outside influence.


Regular readers can support Behind The Black with a contribution via paypal:


Or with a subscription with regular donations from your Paypal or credit card account:


If Paypal doesn't work for you, you can support Behind The Black directly by sending your donation by check, payable to Robert Zimmerman, to

Behind The Black
c/o Robert Zimmerman
P.O.Box 1262
Cortaro, AZ 85652

Seasonal frost in a gully on Mars

Frost in a gully on Mars
Click for full image.

Cool image time! The photo on the right, cropped, reduced, and brightened slightly to post here, was part of the April image release from the high resolution camera on Mars Reconnaissance Orbiter (MRO). According to the titled of this release, it purports to show visible frost on what looks like an avalanche debris slope on the rim of a large crater. The frost is the bright streaks on the upper left of the slope.

I wonder. During last month’s 50th Lunar and Planetary Science Conference in Texas, there was one paper that I reported on that showed something very similar to this, and proposed that white streaks like this in a gully were actually exposed snow/ice. They proposed that the snow/ice was normally covered by dust, and the white streaks were where the dust had blown away to reveal the ice below. This in turn would then sublimate into gas, which in turn would cause the gully avalanches over time.

Below is a close-up of the white streaks on this rim.

Close-up of white streaks

In this case the white streaks do appear to be on top of the avalanche debris, which is different than the paper I reference above. There, the streaks looked more like exposed white areas on the smooth slopes above the debris. This difference might explain why the scientists here think this is frost, not exposed buried ice/snow.

That water frost can settle on the surface of Martian slope is intriguing. The slope is in the southern hemisphere and is south facing, which means this slope gets considerably less sunlight. This cold environment will allow frost to gather and remain.

I wonder if there is enough of this kind of frost for future colonists to be able to use. At a minimum, I could see such frost as a survival tool. Imagine you are a Martian prospector, out in the wild, looking for resources you can mine. This frost might be an easy source of water in a very dry desert environment.

Science fiction writers take note!

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

Unfortunately, that is exactly where that journey takes him.

The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

One comment

  • Max

    This is a good catch, there are deep gullies and ravines eroded at the top of the picture which deposits like a delta on top of the avalanche debris. This is where the ice occurs in the picture. I would note that this also could be salt deposits from evaporated ice/or water from seepage in the crater wall.
    At the bottom of the original picture appears to have mudflows with more frost/salt on the leading edges (or the gravity side) of the dunes at the bottom of the slope.
    Lots of dust devil tracks indicates warm/cold dynamics occurring in the crater.

    The most significant part of the picture is the erosion that formed gullies and delta build up deposits that could not of happened without a “fluid liquid” at some point of Mars history. The evidence for subterranean water is strong.

Readers: the rules for commenting!


No registration is required. I welcome all opinions, even those that strongly criticize my commentary.


However, name-calling and obscenities will not be tolerated. First time offenders who are new to the site will be warned. Second time offenders or first time offenders who have been here awhile will be suspended for a week. After that, I will ban you. Period.


Note also that first time commenters as well as any comment with more than one link will be placed in moderation for my approval. Be patient, I will get to it.

Leave a Reply

Your email address will not be published. Required fields are marked *