The Week Junior - USA (2021-11-12)

14

Science and technology

The Week Junior • November 12, 2021

S

cientists have discovered that about 4 billion

years ago, the planet Mars was shaken by

thousands of “super eruptions.” These are the most

violent form of volcanic eruption. Over a period

of 500 million years, the blasts tore through the

planet’s surface, spewing carbon dioxide, sulfur

dioxide, and water vapor. They showered

the planet with enough rock and gas

to fi ll 400 million Olympic-size

swimming pools and spread a

thick blanket of ash thousands

of miles from the eruption site.

Today, some parts of

northern Mars are scarred by

huge craters called calderas.

Astronomers used to think these

features were formed by huge asteroids

(space rocks) hitting the surface, but a 2013 study

revealed hidden clues that they were not linked to

impacts. Impact craters are almost always circular,

and the calderas are oval-shaped. The calderas

also had deep fl oors and benches of rock along the

walls, which are signs that the area had collapsed.

This supported an alternative theory, which

was that the scars were the collapsed remains of

huge ancient volcanoes. A team of scientists set

out to fi nd traces of volcanic ash that was spread

by eruptions when the volcanoes were active.

The team was led by Patrick Whelley, a geologist

(scientist who studies rocks and soil to learn about

a planet’s history) for the US space agency NASA.

Using images taken by NASA’s Mars

Reconnaissance Orbiter satellite, Whelley and

his team studied the walls of impact

craters and canyons on Mars. They

found areas that had many

layers of ash, which contained

volcanic minerals. Each layer

was deposited by a super

eruption, and there had been

thousands of them. “Each one

of these eruptions would have

had a signifi cant climate impact—

maybe the released gas made the

atmosphere thicker or blocked the Sun and made

the atmosphere colder,” Whelley said.

One intriguing question is why the calderas are

concentrated in one region of Mars, called Arabia

Terra. Whelley’s colleague Jacob Richardson hopes

this mystery will inspire further research. “People

are going to read our paper and go, ‘How? How

could Mars do that? How can such a tiny planet

melt enough rock to power thousands of super

eruptions in one location?’” Richardson said.

Powerful volcanoes shaped Mars

CHRIS BUTLER/SCIENCE PHOTO LIBRARY; NASA/JPL/CALTECH/UNIVERSITY OF ARIZONA; ITTIZ

DID YOU
KNOW?
The last super eruption
on Earth was 22,
years ago in Taupo,
New Zealand.

Where did the water go?

Though there is no known water on the

surface of Mars today, scientists believe it did

fl ow there billions of years ago. But where did

it go? A new study suggests that it may have

simply slipped away into space.

A team of researchers analyzed Martian

rocks that have fallen to Earth. They found

that the red planet did not have the right

chemical makeup to hold on to water. This

could be because Mars is about half of Earth’s

size and has a weaker pull of gravity, which

makes it easier for lightweight chemicals like

water to escape from its grasp. If Mars could

not hold on to water, which is essential for life

to exist, it would have been di cult for any

life forms to survive there.

An illustration

of volcanoes

erupting on Mars

X mosxsxur

Layers of ancient

ash on Mars