When NASA announced in May that the InSight Mars lander was shutting down after a 4-year mission studying the planet’s crust, mantle and core, headlines focused on the robot’s landmark discoveries on Earth. seismic activity and earthquakes.
But though they’ve received less attention, a secondary set of observations are also leading to important discoveries about the Red Planet’s weather and environment, including the first measurements of magnetism taken from the surface of Mars. .
“We’ve been waiting forever to have a magnetometer on the surface of Mars,” said Rob Lillis, associate director of planetary sciences at the University of California, Berkeley. “So these results were really impactful.”
First look at magnetism from the surface
The magnetometer is part of InSight’s auxiliary payload sensor suite. This instrument cluster, which also includes sensors measuring wind, temperature and pressure, was originally intended to monitor and measure conditions that could affect the lander’s seismic readings.
“Their main purpose was basically to be a support suite for the seismometer,” said Catherine Johnson, a co-investigator with the InSight science team and a professor in the Department of Earth, Ocean and Atmospheric Sciences at the University of British Columbia, which worked with the lander’s magnetism data.
But even though the instruments were more limited than they would have been on a mission entirely dedicated to these observations, they still offered an unprecedented opportunity to collect data from the surface of the planet, she said. declared. Scientists could create a more complete picture of global weather patterns around InSight and the nearby Curiosity rover and add ground-based magnetism measurements that complement orbital observations from satellites like Mars Atmosphere and Volatile Evolution (MAVEN) and the Mars Global. Surveyor.
“We knew quite a bit about the planet’s magnetic field environment, but all of these observations were from above the atmosphere,” Johnson said. “It was our first chance to see it on the surface of the planet.”
Magnetism researchers have focused on two key sets of scientific questions. One group focused on crustal magnetism. Although Mars no longer has a planetary magnetic field, these rocks indicate that such a field once existed.
“Knowing more about these rocks is actually very important because it can help us better constrain the timing and strength of this ancient magnetic field on Mars,” Johnson said. “All of this ties into InSight’s overarching goal, which is to understand the inner structure and evolution of the planet.”
Previously, orbiters on Mars had observed that the planet’s crustal magnetic fields were much stronger than those on Earth, Lillis noted. The scientists wanted to know if this was entirely due to the magnetization of the rocks themselves or if other factors contributed to it.
In fact, InSight found that the rocks were even more strongly magnetized than previously thought. “We thought the fields…could be 100 nanotesla,” he said. “Turns out they were about 2,000 nanotesla, or 20 times more powerful than any model predicted.”
The second cluster of questions about magnetism focused on how the magnetic field at the landing site would change over time, Johnson said. A number of factors contribute to fluctuations in magnetic fields, including space weather, the planet’s day-night cycle, and electrical currents generated in Mars’ weak atmosphere.
Understanding these fluctuations can provide information to help explain climate and atmospheric patterns on the planet. It can also lead to a better understanding of space weather.
“These are also system-wide questions that relate to understanding the planet as a whole,” Johnson said. “Magnetic fields are cool because they connect the deep interior of the planet not just to the atmosphere but to the space around it.”
It was particularly useful to have simultaneous observations of InSight on the surface and MAVEN in orbit, Lillis said.
A bittersweet end
Johnson said she had mixed feelings seeing the mission come to an end.
“We met and exceeded our main mission objectives and learned more than expected,” she said. “But the sad thing is that all the instruments worked very well. It’s not like the instruments are deteriorating or we’re not getting good data anymore. The mission will end as its dust-covered solar panels will no longer be able to power the lander.
The timing is particularly unfortunate because the Sun is now heading towards solar maximum, a multi-year period of increased solar activity that would have led to some interesting observations of magnetism, she added.
While InSight may be shutting down, that’s not the end of the study of magnetism from the surface of Mars. Johnson and Lillis noted that China’s Zhurong rover is equipped with a magnetometer, and they said they hoped its observations would be made public soon. They also said InSight laid the groundwork and served as a proof of concept for future NASA missions to study Mars’ magnetic fields in more detail.
“It just gave us a little taste,” Lillis said, “but it’s a very tantalizing taste.”
— Ilima Loomis (@iloomis), science writer