Five ways NASA’s InSight helped us understand Mars better

Curtains fell on the space agency NASA’s Interior Exploration using Seismic Investigations (InSight) mission on December 21 when the team was unable to establish contact with the spacecraft even after two consecutive attempts. The InSight spacecraft was launched in 2018 to study the deep interiors and composition of Mars.

NASA’s team concluded that the spacecraft’s solar-powered batteries run out of energy, referring to it as ‘dead bus’. The last time InSight communicated with Earth was on December 15. A day before the formal announcement, InSight’s Twitter handle tweeted an image, saying that it may be the last one that it would be sharing since it was running on low power.

It landed on Mars’ surface on November 26, 2018. The mission was initially planned for a period of 709 sols (the name for Martian days, close to 730 Earth days). InSight, however, lasted for 1,445 sols.  “InSight has transformed our understanding of the interiors of rocky planets and set the stage for future missions. We can apply what we’ve learned about Mars’ inner structure to Earth, the Moon, Venus, and even rocky planets in other solar systems.” said Lori Glaze, director, NASA Planetary Science Division, said.

Before finally signing off, the mission achieved several milestones. 

Sound of Mars

Just ten days after InSight touched down on Mars, it provided the first ever sound of Martian winds. The sensors on the lander captured ‘a haunting low rumble caused by vibrations from the wind’. These vibrations were blowing at up to 7 meters per second speed and were found to be consistent with the dust devils (convective vortices loaded with dust) in the landing area which were earlier observed from the orbit.

Calling it an unplanned treat, InSight principal investigator at NASA's Jet Propulsion Laboratory (JPL) Bruce Banerdt said that by capturing the motion caused by sound waves, InSight achieved one of the key expectations of measuring motion on the red planet. 

Proof of seismic activity on Mars

In April 2019, InSight reported a faint seismic signal from Mars, the first recorded trembling from inside the planet. The spacecraft was able to pick up cues for the small seismic event due to the sensitive seismometer called Seismic Experiment for Interior Structure (SEIS) installed on it. NASA called the detection of these tiny quakes a big engineering feat. 

“We’ve been waiting months for a signal like this. It's so exciting to finally have proof that Mars is still seismically active,” Philippe Lognonné, SEIS team lead at the Institut de Physique du Globe de Paris (IPGP) in France had then said.

Post that, InSight recorded several ‘Marsquakes’, including two monster-quakes observed in August 2021 (of magnitude 4.2) and the next one in May 2022 (magnitude 5). Overall, the lander detected more than 1,300 quakes since landing on Mars.

‘Insight’ on Mars’ weather

NASA’s InSight doubled up as Mars’ weather reporter through its lifetime. The lander had a package of sensors named the Auxiliary Payload Subsystem (APSS) to provide round-the-clock weather information, much more than any other previous Martian mission. The data was recorded every second of each Sol and regular updates were sent back to Earth.

The lander also had Temperature and Wind for InSight (TWINS) tools. These were two long east and west facing booms to sense wind and temperature. Provided by Spain’s Centro de Astrobiología, this tool could measure heat loss and air temperature. Notably, the TWINS sensors were originally built for NASA’s earlier Curiosity rover in its Rover Environmental Monitoring Station (REMS).

Deep interiors of Mars

Before InSight, NASA’s rovers and orbiters studied only Mars’ surface. InSight helped change that, revealing information on the planet’s deep interiors, thanks to its seismometer. The information collected from the lander’s seismometer helped confirm that Mars’ centre is molten. Simon Stähler of the Swiss research university ETH Zurich, who wrote a research paper on Mars’ core based on InSight’s data, said, “It took scientists hundreds of years to measure Earth’s core; after the Apollo missions, it took them 40 years to measure the Moon’s core. InSight took just two years to measure Mars’ core.”

Further, InSight’s data also showed that Mars’ crust was thinner than expected at 20 km. Beneath the crust lied the mantle running 1,560 km below the surface.

Magnetic fields

InSight was able to measure the magnetic field strength and direction. This information helped scientists conclude that the magnetic field on Mars is ten times stronger than that predicted by satellite-based models. The InSight seismic data, along with geological mapping suggested that a majority of the magnetization sources are carried on 3.9-billion-year-old basement rocks.

These magnetic fields would offer a peak into Mars’ evolution and structure, with atmospheric and space environments.