... and it could require us to rethink the planet’s history
by Ali Sundermier
Using
the Curiosity Rover, the scientists detected a mineral called tridymite
that, until now, they thought could only be created in extremely hot
temperatures.
The discovery
of this tridymite might rewrite the history of the planet, suggesting
that it might once have been hotter than we previously thought, and home
to monstrous volcanoes.
The
scientists found the tridymite with a special instrument on the rover
that shoots x-rays at material to identify the crystal structure of
minerals.
“It was the last
mineral we expected to see,” said Richard Morris, NASA planetary
scientist and lead author of this study. “If this stands test of time it
has a lot of implications for how Mars evolved. We may have to rethink a
few things.”
On Earth,
tridymite is formed at extremely high temperatures in an explosive
process called silicic volcanism. Mt. St. Helens, known for having the
deadliest volcanic event in American history, is an example of a silicic
volcano.
These volcanoes
form as a result of plate tectonics: Plates shifting in Earth’s outer
shell dive deep into the Earth’s mantle, carrying water with them. They
melt and form a mixture of molten rock, or magma, which forces its way
to the surface, where it explodes and flows out. The combination of high
silica content and extremely high temperatures in these volcanoes
creates tridymite.
But as
far as we know, Mars doesn’t have water, or dynamic plates hidden
beneath the surface, and its average temperature is pretty frigid. So
where did this tridymite come from?
That’s
what scientists need to figure out now. And to do this, they’ll either
need to change their understanding of how Mars evolved, or change their
understanding of how tridymite forms.
“We
searched long and hard for terrestrial evidence that tridymite might
form at low temperatures and not imply silicic volcanism,” Morris said.
“We couldn’t find any. This paper will cause a lot of researchers,
including ourselves here at the Johnson Space Center, to look for ways
it could form at lower temperatures.”
The
next step, Morris said, is for scientists to run experiments and
reexamine terrestrial systems in more detail to look for evidence of
tridymite. Either way, what they find will shake up our understanding of
the Red Planet.
“Mars is a
different place,” Morris said. “Processes are different there. There may
be something weird going on that we just don’t recognize yet.”
No comments:
Post a Comment