Mars Developed More Like Earth, Scientists Now Say
Mars in its infancy might have been sculpted by the same process that has shaped Earth’s evolution, channeled the development of its life forms and keeps its face fresh and young, according to new evidence that scientists say could revolutionize their understanding of the Red Planet.
On Mars, however, the process ground to a halt more than 4 billion years ago.
The findings from the Mars Global Surveyor spacecraft will, if confirmed, provide the first direct evidence that the planet transforming process known as plate tectonics is not unique to Earth, an international research team reported Thursday at a NASA news conference and in today’s issue of the journal Science.
On Earth, the distinct magnetic signature of plate tectonics is written along great seams on the bottoms of oceans. The orbiting surveyor has detected a similar signal on Mars.
“We had no idea we’d see anything of this magnitude,” said Jack Connerney of NASA’s Goddard Space Flight Center in Greenbelt, Md. “It was mind-blowing, really.”
Until now, conventional wisdom was that the Martian crust consisted of a single shell rather than interacting plates, and more closely resembled Mercury and the moon as a cold, stony world. The new evidence suggests that Mars has a more complex history, much more similar to Earth’s than previously imagined.
The ancient highlands of the Martian southern hemisphere, in the new scenario, would be viewed as remnants of early “oceanic” crust, reworked by later meteorite bombardment, volcanic flows and other events, according to the Connerney team.
On Earth, plate tectonics is the process in which giant fragments, or plates, of rigid crust float on hot, underlying material and grind slowly against one another, sometimes colliding, sometimes diverging. Plate tectonics revolutionized ourunderstanding of Earth, as geologists realized that it provided a unified explanation for a wide variety of phenomena including the location of the Pacific Ocean’s volcanic “ring of fire,” the distribution of earthquakes, the construction of mountain ranges, and the fact that ancient fossils and rocks from seemingly common homes have been found separated by whole oceans. Some scientists have argued that without it, advanced life would never have evolved.
Remarkably, the Mars Global Surveyor has detected in the oldest Martian crust the same eerie magnetic “bar code” pattern that convinced scientists on Earth that plate tectonics was a reality here.
Norman F. Ness of the University of Delaware, a member of the research team, compared the similar Martian stripes to “faded tattoos on an aging space sailor,” located “perhaps where segments of sea floors spread apart.” The magnetic remnants support the notion of a once-lush Martian paradise, where volcanoes belched hot gas and meandering rivers carved valleys into the planet’s russet plains, he said. Today, the planet is cold and barren.
