Beneath the surface of Mars lie an array of mysterious “blobs” that might hold clues about the earliest days of our solar system. NASA’s InSight Lander discovered the dense lumps scattered through the planet’s mantle.
Marsquakes
From 2018 to 2022, the InSight Lander monitored and recorded data from 1,319 marsquakes. These quakes produce seismic waves, which change slightly as they move through different materials. Astronomers sought the data to study the planet’s interior structure, and have been able to determine the depth and composition of Mars’ crust, mantle, and core.
While analysing the data, researchers noticed that in some of the marsquakes the seismic waves exhibited unusual behaviour. They were slowing down, hitting dense blobs of material in the mantle. Some of these mysterious blobs were huge, with widths up to 4km.
“When we first saw this in our quake data, we thought the slowdowns were happening in the Martian crust,” co-author of the new study, Tom Pike, said in a statement. “But then we noticed that the farther seismic waves travel through the mantle, the more these high-frequency signals were being delayed.”
Early impacts
Researchers think that objects crashing into Mars during the early days of the solar system created the blobs of dense material.
“What we’re seeing is a mantle studded with ancient fragments,” lead author Constantinos Charalambous explained. Mars does not have tectonic plates like Earth; the movement of tectonic plates constantly recycles our crust and upper mantle. On Mars, this doesn’t happen. Mars has one single plate, which means there is much less activity, and this is what allowed the lumps to form.
“These colossal impacts unleashed enough energy to melt large parts of the young planet into vast magma oceans,” explained Charalambous. “As those magma oceans cooled and crystallised, they left behind compositionally distinct chunks of material, and we believe it’s these we’re now detecting deep inside Mars.”
A solid inner core
That was not the only discovery revealed this week. Analysis by a team of Chinese and American scientists revealed that the planet appears to have a solid inner core. This upends previous assumptions.
Seismic data from InSight suggests there is a 600km-wide solid mass at the centre of the planet. “Our results suggest that Mars has a solid inner core making up about one-fifth of the planet’s radius, roughly the same proportion as Earth’s inner core,” lead investigator Daoyuan Sun said.
