On Christmas Eve 1968 three Americans became the first humans to visit another world. What they did to celebrate was unexpected and profound, and will be remembered throughout all human history. Genesis: the Story of Apollo 8, Robert Zimmerman's classic history of humanity's first journey to another world, tells that story, and it is now available as both an ebook and an audiobook, both with a foreword by Valerie Anders and a new introduction by Robert Zimmerman.
"Not simply about one mission, [Genesis] is also the history of America's quest for the moon... Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America's greatest human triumphs." --San Antonio Express-News
Today’s cool image is located near the Martian equator, in the middle of Arabia Terra, the most extensive region of the transition zone between the low northern plains and the southern cratered highlands. Taken on May 9, 2020 by the high resolution camera on Mars Reconnaissance Orbiter (MRO) and cropped to post here, the photo shows some layered mesas surrounded by a terraced and scalloped terrain with dust filling the low spots.
This is likely to be a very dry place on Mars. At only 2 degrees north of the equator, the evidence so far suggests that if there is a buried ice table (like the water table on Earth), it will be much deeper than at higher latitudes. The terrain reflects this, looking reminiscent of Monument Valley in the American southwest. In fact, the satellite image below, which I grabbed from MapQuest, shows a typical mesa in Monument Valley.
Shown at about the same scale as the martian photo above, the similarities are striking. Both have layers, tall mesas, and dry terrain. The differences are also important. The Earth mesas show evidence of water erosion by their softened edges as well as the dry streambeds along the big mesa’s edges. On Earth there are trees in those dry streambeds. Earth also has dust, but no scalloped terrain, at least none visible at this scale.
Ironically, the cause of the erosion that created these mesas in both places is possibly quite similar, wind in recent eons but possibly water/ice far in the past, when the entire planet’s climate was different. For Mars this remains a guess.
The overview map to the right gives the larger context. The white cross is the location of these mesas. Arabia Terra is the large green region east of Chryse Planitia and Valles Marineris.
My guess that this location is dry comes not only because it is at the equator. It is also quite far from the northern lowlands and is very close to the cratered highlands. If an intermittent ocean in the northern lowlands once lapped against Arabia Terra, its shoreline ebbing and flowing as the Martian climate changed, that shoreline would have been far to the north and west of this location. Water and ice might have once been here, but that was likely a very very long time ago.
My July fund-raiser for Behind the Black is now over. The support from my readers was unprecedented, making this July campaign the best ever, twice over. What a marvelous way to celebrate the website's tenth anniversary!
Thank you! The number of donations in July, and continuing now at the beginning of August, is too many for me to thank you all personally. Please forgive me by accepting my thank you here, in public, on the website.
If you did not donate or subscribe in July and still wish to, note that the tip jar remains available year round.
Regular readers can support Behind The Black with a contribution via paypal:
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
Cortaro, AZ 85652