A NASA spacecraft designed to drill down into Mars' interior has landed on the planet after a perilous, supersonic plunge through its red skies, setting off jubilation among scientists who had waited in white-knuckle suspense for confirmation to arrive across 160 million kilometres of space.
Flight controllers at NASA's Jet Propulsion Laboratory in Pasadena, California, leaped out of their chairs, screaming, dancing and hugging, upon learning that InSight had arrived on Mars, the graveyard for a multitude of previous missions.
"Touchdown confirmed!" a flight controller called out just before 3pm EST, instantly dispelling the anxiety that had gripped the control room as the spacecraft made its six-minute descent.
Because of the distance between Earth and Mars, it took eight minutes for confirmation to arrive, relayed by a pair of tiny satellites that had been trailing InSight throughout the six-month, 480-million-kilometre journey.
The two satellites not only transmitted the good news in almost real time, they also sent back InSight's first snapshot of Mars just four minutes after landing.
The picture was speckled with dirt because the dust cover was still on the lander's camera, but the terrain around the spacecraft looked smooth and sandy with just one sizeable rock visible.
It was NASA's - indeed, humanity's - eighth successful landing at Mars since the 1976 Viking probes, and the first in six years. NASA's Curiosity rover, which arrived in 2012, is still on the move on Mars.
"Flawless," declared JPL's chief engineer, Rob Manning.
InSight, a $US1 billion ($A1.4 billion) international project, includes a German mechanical mole that will burrow down five metres to measure Mars' internal heat.
InSight wasn't out of the woods yet: NASA awaited word on Monday night on whether the spacecraft's vital solar panels successfully unfolded. The panels must open to generate power; otherwise, the mission is a bust.
Over the next few "sols" - or Martian days of 24 hours, 39 minutes - flight controllers will also assess the health of InSight's all-important robot arm and its science instruments.
NASA went with its old, straightforward approach this time, using a parachute and braking engines to get InSight's speed from 19,800km/h when it pierced the Martian atmosphere, about 114km up, to 8km/h at touchdown.
The danger was that the spacecraft could burn up in the atmosphere or bounce off it.
The three-legged InSight settled on the western side of Elysium Planitia, the plain that NASA was aiming for.
The 360-kilogram InSight is stationary and will operate from the same spot for the next two years, the duration of a Martian year.
