The US space agency's unmanned Mars Insight lander, which touched down on the Red Planet last month, has successfully deployed its key, quake-sensing instrument on the alien world's surface, NASA said Thursday.

The seismometer, known as the Seismic Experiment for Interior Structure, or SEIS, was made by the French space agency, CNES.

‘Seismometer deployment is as important as landing InSight on Mars,’ said InSight principal investigator Bruce Banerdt of NASA's Jet Propulsion labouratory.

‘The seismometer is the highest-priority instrument on InSight: We need it in order to complete about three-quarters of our science objectives.’

The spacecraft used its robotic arm to place the seismometer on the ground in front of the lander, 5.4 feet (1.64 meters) away, on Wednesday, NASA said.

The tool aims to help scientists better understand the interior of Earth's neighboring planet by studying ground motion, also known as marsquakes.

The goal of the two-year mission is to create the first three-dimensional map of Mars' interior to better understand how rocky planets, like Mars and Earth, took shape billions of years ago.

‘Having the seismometer on the ground is like holding a phone up to your ear,’ said Philippe Lognonne, principal investigator of SEIS from Institut de Physique du Globe de Paris (IPGP) and Paris Diderot University.

‘We're thrilled that we're now in the best position to listen to all the seismic waves from below Mars' surface and from its deep interior.’

The $993 million Mars Insight landed on Mars November 26.