Three things we learned from NASA’s Insight


The Insight space probe will explore the soil of Mars

NASA’s Insight module landed on Mars on November 26, 2018 to study the planet’s deep interior. Slightly higher than the Sun (Mars year), the fixed lander has detected more than 480 earthquakes and collected the most detailed meteorological data from any mission sent to the surface of Mars. The Insight study, which struggled to dig underground to measure the planet’s temperature, has also made progress.

The surfaces of Mars and Earth were once very similar. Both were warm, humid and covered with a thick atmosphere. But three or four billion years ago, these two worlds went different paths.

Insight’s mission – seismic investigations, internal exploration using geodesy and heat transfer – is to help scientists compare the Earth to its rusty brother.

Study of the internal composition of Mars. Here are three discoveries about our red neighbors in the sky.

A faint “murmur” is the norm

The Insight seismometer, supplied by the French space agency CNES (Center National D’Tods Spadiels), is sensitive enough to detect small sounds from large distances. But it wasn’t until April 2019 that seismic experts from the Marscake Service, in collaboration with EDH of Zurich, detected their first earthquake on Mars.

Since then, Mars has lost more time, trembles frequently, and although slower, has a magnitude greater than 3.7 without earthquakes.

No more than 4 earthquakes Indicates a mysteryIt takes into account the frequency with which the Red Planet is shaken by small earthquakes.

“It’s kind of surprising that we haven’t seen a big event,” said Mark Bonning, NASA’s JBL seismologist in Southern California who leads the Insight mission. “It might tell us something about Mars, or it might tell us something about our luck.”

Say it another way: Mars is more stable than expected – or Insight landed mostly during quiet times.

Seismologists will have to wait patiently for these large earthquakes to study the layers below the surface. “Sometimes we get great sparks of surprising information, but more often than not it’s just ‘junk food’,” he said. Bruce Bonard JPL, Principal Investigator of Insight. “It’s more like trying to follow the path of complex clues than giving answers to a well-decorated gift.”

Wind can cover earthquakes

When Insight started detecting earthquakes, they became more regular and at some point they happened every day. Then, at the end of June this year, the results were essentially suspended. Since then, only five earthquakes have been detected, all since September.

Scientists think The winds of Mars are the reason these days The earthquake is empty: the planet entered the windy season of Mars in June. This work knew that the wind would affect the measurement of the seismic sensitivity of the Insight, which was equipped with a wind dome and a heat shield. But the wind still shakes the ground and makes a noise that hides the earthquakes.

It may also have contributed to the prolonged seismic silence before Insight’s first detection, as the block landed when a regional sandstorm was resolved.

“Before landing, We had to guess how the wind would affect it Superficial vibrations, “Bonert said.” We found that we need to focus more on the air because we are working with much smaller events than we focus on on Earth.

No surface waves

All earthquakes have two sets of waves that travel inward: secondary waves (B waves) and secondary waves (S waves). They also spread over the surface as part of a third type called surface waves.

On Earth, seismologists Use surface waves to learn Read more about the internal structure of the planet. Before reaching Mars, Insight’s seismologists expect these waves to give a view of a substrate called the mantle at a distance of 400 km from the interior. But Mars continues to offer mysteries: despite hundreds of earthquakes, nothing adds to the surface waves.

“Earthquakes without surface waves aren’t all that uncommon, but it was surprising,” Baning said. “For example, we cannot see surface waves on the moon, but only because the moon is more scattered than the moon.”

The dry lunar crust is more broken than Earth and Mars, Seismic waves jump in a very large form that can last over an hour.

The absence of surface waves on Mars may be linked to extensive fractures within the first 10km below Insight, or the earthquakes detected by Insight come from the depths of the planet because they do not produce strong surface waves.