An "exquisitely sensitive" detector attached to NASA's InSight lander on Mars has captured the low rumble of marsquakes — much like earthquakes — and an assortment of otherworldly sounds.

Key points: The seismometer has detected more than 100 events, but only 21 are considered strong marsquake candidates

The seismometer has detected more than 100 events, but only 21 are considered strong marsquake candidates The rest could be marsquakes — or something else

The rest could be marsquakes — or something else The low rumbles and "dinks and donks" had to be enhanced to be audible to the human ear

Scientists have released two audio clips of seismic activity on the planet after the dome-shaped Seismic Experiment for Interior Structure (SEIS) was set down on its surface late last year.

One of the quakes recorded was magnitude 3.7 and the other was magnitude 3.3.

The sounds, recorded in May and July, had to be speeded up and enhanced for humans to hear.

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The seismometer has detected more than 100 events, but only 21 are considered strong marsquake candidates.

The rest could be marsquakes — or something else.

"[The recordings] suggest that the Martian crust is like a mix of the Earth's crust and the Moon's," NASA's Jet Propulsion Laboratory said.

"Mars, with its cratered surface, is slightly more Moon-like, with seismic waves ringing for a minute or so, whereas quakes on Earth can come and go in seconds.

The French seismometer is so sensitive it can hear the Martian wind as well as movements by the lander's robot arm and other "dinks and donks", as the team calls them.

"It's been exciting, especially in the beginning, hearing the first vibrations from the lander," said Imperial College London's Constantinos Charalambous, who helped provide the audio recordings.

"You're imagining what's really happening on Mars as InSight sits on the open landscape," he added.

InSight arrived on Mars last November and recorded its first seismic rumbling in April.

A German drilling instrument, meanwhile, has been inactive for months, but scientists are trying to salvage the experiment to measure the planet's internal temperature.

The so-called mole is meant to penetrate five metres beneath the Martian surface, but has managed barely 30 centimetres.

Researchers suspect the Martian sand isn't providing the necessary friction for digging, causing the mole to helplessly bounce around rather than burrow deeper, and to form a wide pit around itself.

AP/AFP