Based on a study of alluvial fans on Mars, river sediment thought to have been placed at the foot of mountains, scientists have concluded that liquid water could have been flowing from as 2.5 to 3.6 billion years ago.
“We’ve known for decades that Mars had rivers and lakes around 3.5 billion years ago, but in the past few years there has been a growing body of evidence that substantial amounts of liquid water continued to erode the Martian surface for hundreds of millions of years,” said Morgan, lead author on “The global distribution and morphologic characteristics of fan-shaped sedimentary landforms on Mars” that appears in Icarus. “Water-formed landforms, such as river deltas and alluvial fans, are the most unambiguous markers of past climate. So we conducted a global survey for these features and explored patterns in their distribution and morphologic properties.”
Morgan and co-authors including PSI Senior Scientist Alan Howard found that alluvial fans are found at lower elevations than the more ancient valley networks, suggesting that stable liquid water became restricted to lower, warmer regions as Mars cooled and dried.
…What is particularly interesting about the Martian fans is that many formed much later than the valley networks, which have long been considered the strongest evidence for surface water on early Mars. Valley networks largely date to around 3.6 billion years ago, but alluvial fans date to 2.5 to 3 billion years ago.
This research merely increases the fundamental geological mystery of Mars. While the surface evidence strongly tells us that liquid water once flowed on the surface, no climate model exists that satisfactorily makes that possible. The atmosphere appears to have always been too cold and thin for liquid water.
Now available in hardback and paperback as well as ebook!
From the press release: In this ground-breaking new history of early America, historian Robert Zimmerman not only exposes the lie behind The New York Times 1619 Project that falsely claims slavery is central to the history of the United States, he also provides profound lessons about the nature of human societies, lessons important for Americans today as well as for all future settlers on Mars and elsewhere in space.
Conscious Choice: The origins of slavery in America and why it matters today and for our future in outer space
, is a riveting page-turning story that documents how slavery slowly became pervasive in the southern British colonies of North America, colonies founded by a people and culture that not only did not allow slavery but in every way were hostile to the practice.
does more however. In telling the tragic history of the Virginia colony and the rise of slavery there, Zimmerman lays out the proper path for creating healthy societies in places like the Moon and Mars.
“Zimmerman’s ground-breaking history provides every future generation the basic framework for establishing new societies on other worlds. We would be wise to heed what he says.” —Robert Zubrin, founder of founder of the Mars Society.
All editions available at Amazon, Barnes & Noble, and all book vendors. The ebook can be purchased direct from my ebook publisher, ebookit, in which case you don't support the big tech companies and I get a bigger cut much sooner. Note that the price for the ebook, $3.99, goes up to $5.99 on September 1, 2022.
Autographed printed copies are also available at discount directly from me (hardback $24.95; paperback $14.95). Just email me at zimmerman @ nasw dot org.