Click for full image.
Click for full image.
Back in January 2018 planetary scientists released a paper announcing the discovery of a number of Martian cliff faces, or scarps as they called them, that all appeared to expose an underground layer of ice.
Those cliffs were mostly located to the southeast of Hellas Basin, the basement of Mars that is also advantageous for human colonization because its lower elevation means its atmosphere is thicker. (For example, that thicker atmosphere would make air transportation more practical.)
The two images to the right show what they listed as scarp #1 in their paper, rotated, cropped, and reduced to post here. The first image was taken in May 2011, with the second taken in December 2018, and was part of the March image release from the high resolution camera of Mars Reconnaissance Orbiter (MRO).
The December 2018 image was taken almost a year after the paper release, and was titled “Scarp Monitoring.” I therefore wondered whether the scientists had identified any changes. They theorize that these scarps form when the exposed ice slowly sublimates to gas into the atmosphere, causing the cliff face to collapse and retreat, which in the case of scarp #1 would be a retreat to the north. The terraces below the scarp suggest previous cliff locations. In their paper they noted evidence of some changes in the studied scarps, including some fallen boulders, as well as color changes that suggest some evolution.
The rate of that retreat is not known with precision, but based on the facts presently at hand, the scientists have estimated that it took about a million years to form this scarp. Whether any evidence of this retreat would be visible in only seven years is the purpose of these scarp monitoring images.
Do you see any difference? I don’t, but because I also don’t trust my expertise I decided to email the paper’s lead author, Colin Dundas of the U.S. Geological Survey’s Astrogeology Science Center. His emailed comments are most interesting.
I haven’t yet analyzed the most recent data … but some of the mottled color/albedo changes that we mentioned in the paper were at this scarp, so you might wish to say something like “no major changes”. For context, we expect exposed ice to slowly sublimate and be covered by dust.
He then confirmed that this slow sublimation would be below the resolution of the high resolution camera of MRO, and thus would likely not be visible in these images. The changes in color as well as the periodic fall of boulders however both suggest this is the process that is happening. As he added,
It could be many years before we see changes at [the scale of this camera], but the color and albedo may be changing as thin dust lags form and are swept away.
Thus, some changes should eventually become visible, but to spot them will take time.
Monitoring these scraps will be crucial for future exploration. The ice here is very readily available, as it is exposed and should be relatively easy to access. Moreover, tracking might tell us whether it will be easier to get at this ice from the top of the cliff by drilling down, or approach it from the bottom. Some of the ice bands in these scarps was very close to the surface at the top of the cliff.
I must unfortunately ask you for your financial support because I do not depend on ads and rely entirely on the generosity of readers to keep Behind the Black running. You can either make a one time donation for whatever amount you wish, or you sign up for a monthly subscription ranging from $2 to $15 through Paypal or $3 to $50 through Patreon.
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.
Your support is even more essential to me because I not only keep this site free from advertisements, I do not use the corrupt social media companies like Google, Twitter, and Facebook to promote my work. I depend wholly on the direct support of my readers.
You can provide that support to Behind The Black with a contribution via Patreon or PayPal. To use Patreon, go to my website there and pick one of five monthly subscription amounts, or by making a one-time donation. For PayPal click one of the following buttons:
If Patreon or Paypal don'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
Cortaro, AZ 85652
Or you can donate by using Zelle through your bank. You will need to give my name and email address (found at the bottom of the "About" page). The best part of this electronic option is that no fees will be deducted! What you donate will be what I receive.