Exploring the red planet

A Nasa probe on Mars has detected a seismological tremor on the red planet that is being dubbed a “marsquake”.

The US space agency has announced that on 6 April, its InSight lander detected a faint seismic signal that is believed to have emanated from beneath the surface of the planet, as opposed to being caused by forces above such as wind, The Guardian reports. The breakthrough comes five months after the robotic probe touched down on Mars.

French space agency CNES, which built the seismometer, says it had been “waiting months for our first marsquake”.

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“It’s so exciting to finally have proof that Mars is still seismically active,” the agency said in a statement. “This first event officially kicks off a new field - Martian seismology.”

So what is a marsquake?

Mars does not have tectonic plates and does “not produce the kind of cataclysmic quakes that we sometimes experience on Earth”, explains Vice’s Motherboard.

Instead, quakes on Mars are caused by “faults or fractures in the crust” which in turn may be the result of meteorite impacts, “surface shrinkage due to planetary cooling, or the pressure of magma pushing up toward the surface”, says Live Science.

Humans have tried to measure Martian tremors with seismometers since the 1970s, but have not been successful until now.

How was it measured?

In November, Nasa’s InSight probe touched down on the red planet carrying an instrument dubbed the Seismic Experiment for Interior Structure (SEIS), designed by CNES. The instrument was then deployed to the surface of Mars the following month.

Nasa’s website reports that on Earth, high-quality seismometers are “sealed in underground vaults to isolate them from changes in temperature and weather”. Because of the more extreme conditions on Mars, SEIS was fitted with “several ingenious insulating barriers, including a cover... called the Wind and Thermal Shield, to protect it from the planet’s extreme temperature changes and high winds”, the space agency says.

On the lander’s 128th Martian day, a faint rumble was detected by the instrument and recorded by scientists at the Jet Propulsion Laboratory in California.

Professor Tom Pike, one of the SEIS designers, told the BBC that the quake was too small to calculate the source or the distance from the probe to the event.

“It’s probably only a Magnitude 1 to 2 event, perhaps within 100km [62 miles] or so,” he said.

Why is it significant?

The vibrations from marsquakes move through the interior of the red planet and “bump into and reflect off of different materials underground”, says Live Science.

The researchers believe that because different materials transmit and reflect these vibrations in various ways, they will be able to use SEIS data to recreate a 3D view of the Martian interior, giving us a good idea of how the planet was formed.

Unlike on Earth, where constant tectonic activity has erased much of the historical rock formations that might tell us about the origins of our planet, Mars’ lack of tectonic activity means that much of its history is still buried in its interior, untouched for millions of years.

Although the quake recorded was far too small to give scientists any concrete information about the interior of the planet, further tremors should provide more data over time.

Tanya Harrison, a Mars scientist at Arizona State University, told National Geographic that SEIS is “helping paint the picture that Mars is still an active place”.