NASA's InSight lander 'hears' strange sounds on Mars

NASA has released recordings of eerie sounds on Mars picked up by one of its missions to the Red Planet, the InSight lander.

Far below the human range of hearing, these recordings had to be speeded up and slightly processed to be audible through headphones, NASA said on Tuesday.

The spacecraft`s exquisitely sensitive seismometer, called the Seismic Experiment for Interior Structure (SEIS), can pick up vibrations as subtle as a breeze.

The instrument was provided by the French space agency, Centre National d`Etudes Spatiales (CNES), and its partners.

The instrument was designed to listen for quakes on Mars, known as marsquakes.

Scientists want to study how the seismic waves of these quakes move through the planet`s interior, revealing the deep inner structure of Mars for the first time.

But after the seismometer was set down by InSight`s robotic arm, Mars seemed shy. It did not produce its first rumbling until this past April, and this first quake turned out to be an odd duck.

It had a surprisingly high-frequency seismic signal compared to what the science team has heard since then.

Out of more than 100 events detected to date, about 21 are strongly considered to be quakes, NASA said.

The remainder could be quakes as well, but the science team hasn`t ruled out other causes.

SEIS has no trouble identifying quiet quakes, but its sensitive ear means scientists have lots of other noises to filter out.