The flight controllers at NASA's Jet Propulsion Laboratory in Pasadena, California, jumped out of their seats and burst out screaming, applause and laughter when the news arrived.
Two InSight trolling mini-satellites since their takeoff may have provided virtually real-time updates of the supersonic descent of the spacecraft through the reddish sky. The satellite also sent back a quick photo from the surface of Mars.
The image was tainted with debris particles. But the rapid observation of the surroundings revealed a flat surface with little or no rocks – exactly what the scientists hoped for. Better images will arrive in the hours and days ahead.
"What a relief," said Rob Manning, chief engineer of JPL. "It's really fantastic." He added, "Wow, it never gets old."
Manning said that the landing seemed to be flawless.
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"That's what we really hoped and imagined in our minds," he said. "Sometimes things work in your favor."
The three-legged InSight spacecraft reached the surface after going 12,300 mph (19,800 km / h) to zero in six minutes flat as it penetrated the Martian atmosphere, using a parachute and braking the engines.
The radio signals confirming the landing took more than eight minutes to cross the approximately 160 million kilometers between Mars and Earth.
It was NASA's ninth attempt to land on Mars since the 1976 Viking probes. All previous US touchdowns, except one, have been successful.
The last time NASA landed on Mars in 2012 with the Curiosity rover.
Tours were held from coast to coast in museums, planetariums and libraries, as well as Times Square in New York.
"Landing on Mars is one of the hardest jobs that people have to do in planetary exploration," said InSight's senior scientist, Bruce Banerdt, prior to the landing. "It's so difficult, it's so dangerous that there's always a pretty uncomfortable chance that something is not right."
Mars has been the cemetery of a multitude of space missions. Until now, the success rate on the Red Planet was only 40%, counting all attempts at overflight, orbital flight and landing by the United States, Russia and other countries since 1960.
The United States has, however, made seven landings on Mars over the last four decades, not counting InSight, with only one touchdown. No other country has managed to install and operate a spacecraft on a dusty red surface.
InSight fired for Elysium Planitia, a plain near the Martian equator that the InSight team hopes to be as flat as a parking lot in Kansas with little or no rocks.
This is not a rock collecting expedition. Instead, the 360-pound (360-kilogram) static undercarriage will use its 6-foot robotic arm to place a mechanical mole and seismometer on the ground. The self-hammering mole digs 5 meters (16 feet) to measure the internal heat of the planet, while the seismometer listens to possible earthquakes.
Nothing like it has been tried before at our neighbor next door, at nearly 160 million kilometers. No lander has dug more than several inches and no seismometer has ever worked on Mars.
By examining the interior of Mars, scientists hope to understand how the rock planets of our solar system were formed 4.5 billion years ago and why they turned out so different: cold and dry Mars Burning Venus and Mercury and Earth conducive to life.
InSight however has no life detection capability. This will be left to future rovers. NASA's Mars 2020 mission, for example, will collect rocks that will eventually be brought back to Earth and analyzed for evidence of ancient life.
(Copyright © 2018 by The Associated Press, All Rights Reserved.)