[Apr. 29, 1999: NASA's Mars Global Surveyor has discovered surprising new evidence of past movement of the Martian crust, suggesting that ancient Mars was a more dynamic, Earth-like planet than it is today.

Scientists using the spacecraft's magnetometer have found banded patterns of magnetic fields on the Martian surface. The adjacent magnetic bands point in opposite directions, giving these invisible stripes a striking similarity to patterns seen in the crust of Earth's sea floors.]

[Alternate explanations for the banded structure may involve the fracturing and breakup of an ancient, uniformly magnetized crust due to volcanic activity or tectonic stresses from the rise and fall of neighboring terrain.]

[The dynamo likely died a few hundred million years after Mars' formation. One possibility is that later asteroid impacts followed by volcanic activity heated and shocked large areas of the northern crust, obliterating any local magnetic fields and smoothing the terrain," Acuna said. "When the crust cooled, there was no longer a global magnetic field to become frozen in again."

The map also identifies an area in the southern highlands as the oldest surviving unmodified crust on Mars. This area on Mars is where the magnetic stripes are most prominent. The bands are oriented approximately east-to-west and are about 100 miles wide and 600 miles long, although the longest band stretches more than 1,200 miles.

"The bands are wider than those on Earth, perhaps for a couple of reasons," Connerney said. "The Martian crust could have been generated at a greater rate, causing a given magnetic field to be imprinted over a wider area before it reversed direction. Second, the Martian magnetic field may have reversed direction less frequently, which would have given more time for any one field direction to imprint itself in the steadily moving crust, resulting in wider bands.

"In order to call this pattern a crustal spreading center like that observed in the mid-oceanic ridges on Earth, we need to find a point of symmetry, where the pattern on one side matches the pattern on the other. We have not yet found evidence of this type of symmetry," Connerney added.]

---

We get the idea...

Outside of Pluto, Mars has the weirdest orbit 'of the terrestrials'. Hellas (Who knows?(!)?.

Plate tectonics on Mars.