The lander/probe was launched atop an Atlas V rocket from NASA's Vandenberg Air Force Base in California. "NASAInSight heads into space for an approximately six-month journey to Mars where it will take the planet's vital signs and help us understand how rocky planets formed", NASA tweeted soon after the launch at 7.05 a.m. (4.35 p.m. India time).
InSight will dig deeper into Mars than ever before - almost 16 feet, or 5 meters - to take the planet's temperature.
It will place a seismometer on the ground to listen for seismic waves caused by marsquakes - the Martian analog to earthquakes - and by falling meteorites.
Tom Hoffman, InSight project manager at NASA's Jet Propulsion Laboratory (JPL) in Pasadena, California.
The payload will be released about 90 minutes after launch on a 301 million mile (484 million km) flight to Mars. The InSight, which is short for for Interior Exploration using Seismic Investigations, Geodesy and Heat Transport, is expected to touch down in November, joining five other NASA spacecraft on or orbiting around Mars. Only about 40 percent of all missions to Mars from all countries - orbiters and landers alike - have proven successful over the decades.
If all goes well, the three-legged InSight will descend by parachute and engine firings on to a flat equatorial region of Mars - believed to be free of potentially unsafe rocks - on November 26.
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Once on the surface, InSight will begin deploying its primary instruments.
InSight "will probe the interior of another terrestrial planet, giving us an idea of the size of the core, the mantle, the crust - and our ability then to compare that with the Earth", NASA Chief Scientist Jim Green said during a news conference.
Unlike previous Mars missions, such as Opportunity, Spirit and Curiosity, this lander will be a stationary one.
But the quakes do allow for similar studies of the Martian interior. Almost two dozen other Mars missions have been launched by other nations.
"InSight will not only teach us about Mars, it will enhance our understanding of formation of other rocky worlds like Earth and the Moon, and thousands of planets around other stars", said Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate at the agency headquarters in Washington.