YSM Issue 90.5

astronomy
FEATURE
IMAGE COURTESY OF FLICKR
►The study determined that Eridania’s deposits had a hydrothermal
origin, meaning that they formed as a result of underwater volcanic
activity.
IMAGE COURTESY OF J. MICHALSKI ET. AL.
►Previous research has shown that the Eridania Basin is composed
of several sub-basins that were filled at most up to the 1,100 m
elevation line. This suggests that the parts of the lake were between
1-1.5 km deep.
IMAGE COURTSY OF WIKIMEDIA COMMONS
►The study used spectral data collected by NASA’s CRISM, an imaging
spectrometer that was built to search for mineralogical evidence of
water on Mars’ surface.
the human eye, to “look” at chemical compounds. This enables
scientists to see minerals in “colors” absents in visible light, allowing
them to identify the minerals. The infrared data used in
the study was collected through NASA’s CRISM (Compact Reconnaissance
Imaging Spectrometer for Mars), an instrument
on the Mars Reconnaissance Orbiter (MRO) that searches for
mineralogical evidence of past water on Mars’ surface. Satellite
images were used to help the researchers to contextualize their
results in terms of the planet’s actual geography to create a better
interpretation.
The researchers discovered that the Eridania basin contained
iron- and magnesium-rich clays. These substances are widespread
across Mars’ surface; however, the specific types and distribution
of clays present were unusual and sometimes matched
better with terrain on Earth’s seafloors than terrain on Mars.
In addition to clays, the researchers also found evidence of
carbonates, silica, and sulfides—compounds all formed through
hydrothermal activity, or underwater volcanism, on Earth. Using
a crater-counting function, the researchers also determined
that the deposits were about 3.8 billion years old, contemporaneous
with the oldest evidence of life on Earth.
Eridania’s clays may have formed through evaporation. However,
this would have resulted in the production of chemical
compounds not present in the deposits, making this hypothesis
unlikely. An alternative explanation for the deposits is air
fall—for instance, wind could have carried ash from a nearby
volcanic eruption into the basin. However, since no deposits of
similar age were found anywhere outside of the basin, this too
is implausible. Thus, the researchers concluded that the deposits
were most likely created in a hydrothermal context. This is
supported by the presence of large volumes of lava on the basin
floor, indicating that significant volcanic activity occurred at
some point during the basin’s history.
The Eridania basin is unique among other sites on Mars in its
ability to illuminate the conditions surrounding the origin of
life on Earth. Not only does it represent an ancient hydrothermal
environment, but it was also active around the same time
early life thrived on Earth. Michalski hopes that future studies
will continue investigating the details of his group’s current results.
He also hopes for a rover visit to the Eridania basin in the
future. “If we can visit it with a rover and obtain some physical
samples of the terrain, we would surely learn a lot about how
life originates, even if we don’t find direct evidence of life,” Michalski
said.
www.yalescientific.org
December 2017
Yale Scientific Magazine
31