Tampa-NASA is counting down to a nail-biting touchdown Monday of the $993 million Mars InSight, the first spacecraft to listen for quakes and study the inner workings of another rocky planet.

No one is on board the spacecraft, which launched nearly seven months ago and has traveled some 300 million miles (482 million kilometers).

But part of its mission is to inform efforts to one day send human explorers to the Red Planet, which NASA hopes to do by the 2030s.

The lander is the first to reach Mars since 2012, when NASA’s Curiosity rover touched down to scour the surface and analyze rocks for signs that life forms may once have inhabited Earth’s neighbor, now a frigid and dry planet.

InSight must survive tense entry into Mars’ atmosphere, traveling at a speed of 12,300 miles (19,800 kilometers) per hour and swiftly slowing to just five mph (eight kph).

This entry, descent and landing phase begins at 11:47 am in California (1947 GMT) -- and is only half-jokingly referred to at NASA as “Six and a Half Minutes of Terror.” Of 43 missions launched toward Mars, only 18 have made it intact -- a success rate of around 40 percent. All those that made it came from the United States.

“Going to Mars is really, really hard,” said Thomas Zurbuchen, associate administrator for the NASA science mission directorate.

“The exciting part is we are building on the success of the best team that has ever landed on this planet, which is the NASA team with its contractors and its collaborators.”