'Touchdown confirmed': InSight lands on Mars

It was the moment of truth for a NASA project that has been ongoing for six months, the culmination of a 295 million-mile, six-month voyage.

Anxiety was high at NASA, which last attempted a landing on the red planet six years ago.

"I am completely excited and completely nervous, all at the same time," InSight project manager Tom Hoffman said Sunday during a news conference at NASA's Jet Propulsion Laboratory in California. "Everything we've done to date makes us feel comfortable and confident we're going to land on Mars. But Mars could always throw us a curve ball.”

NASA launched the InSight lander on May 5. The mission, which cost $850 million, will study the deep interior of Mars and will help scientists understand the formation and early evolution of Mars and other rocky planets, including Earth.

What makes the landing perilous is that the InSight lander must go from 12,300 mph to 5 mph in six minutes, according to Space.com.

During that time, the spacecraft must fire its descent engines, deploy its parachutes, and hopefully land upright on the Martian surface, according to the The Associated Press.

Even after the spacecraft lands, the InSight team won't know that the stationary spacecraft's solar panels have deployed until 8:35 p.m. EST at the earliest, Space.com reported. That's when NASA's Mars Odyssey orbiter will be in position to relay confirmation to Earth.

Only 40 percent of the missions ever sent to Mars have successfully landed on the planet, and the U.S. is the only nation to land a craft on the surface, NASA officials said. “Since 1965, it (the U.S.) has flown by, orbited, landed on and roved across the surface of the Red Planet.”