1 of 2
This artist's concept depicts the moment that NASA's Curiosity rover touches down onto the Martian surface.

SALT LAKE CITY — When a new generation of a car-sized rover arrives on Mars early next month, NASA will use a never-before-tried landing technique.

The final moments of the flight are so unusual the space agency has stirred excitement with a video entitled  “Curiosity’s Seven Minutes of Terror.”

"When people look at it, it looks crazy," said NASA engineer Adam Steltzner. "Sometimes when we look at it, it seems crazy."

The rover named Curiosity was launched on Nov. 26, 2011. The complex, tricky and exciting landing technique is necessary because of two interrelated factors: Curiosity's heavy weight and the relatively thin atmosphere of Mars.

The Martian atmosphere is thick enough to heat up the spacecraft to temperatures similar to those on the surface of the sun. The biggest parachute ever constructed will be used to slow the spacecraft down. But the atmosphere is too thin to slow such a heavy object down enough to land it safely on the surface of the red planet.

“This thing is a ton," said Patrick Wiggins, NASA Solar System Ambassador to Utah. "I mean, this is a Mini-Cooper size vehicle that's going to be going down onto the surface."

To further prepare for a soft landing, the spacecraft's on-board computer will disconnect the parachute and fire retrorockets. As the spacecraft slows down substantially and approaches the surface of Mars, it immediately encounters a bigger problem: the rocket blast would stir up too much dust.

"And so the way we solve that problem is by using the sky-crane maneuver," said Anita Sengupta, NASA engineer.

The sky-crane maneuver turns the spacecraft into a crane. As it slows down and essentially stops, hovering above the Martian surface, the spacecraft will lower the rover on long cables. When the car-sized rover is safely deposited on Mars, the hovering spacecraft has one last maneuver to perform: flying away and crashing. That's necessary because the spacecraft or its retrorockets could damage the rover. Once the delivery spacecraft crashes a safe distance away, Curiosity can begin its exploration of the planet.

The rover's primary scientific mission is to attempt to answer the question: Was Mars ever suitable for life? Although it's not directly searching for life, it's designed to look for clues about the planet's historic environment and determine if conditions existed in the past that could have promoted or sustained life.

Wiggins is enthusiastic about the new, improved rover, which is much larger than Opportunity, a rover that has been sending back data from Mars since 2004, much longer than expected.

Wiggins says Curiosity brings new capabilities to Mars.

"It's the next step toward humans," Wiggins said. "With luck, we're going to have humans on Mars in my lifetime. These are the little steps we take to get us out there."

During the 23 months after landing, Curiosity will analyze dozens of samples drilled from rocks or scooped from the ground as it explores with greater range than any previous Mars rover. Curiosity will carry the most advanced payload of scientific gear ever used on Mars' surface, a payload more than 10 times as massive as those of earlier Mars rovers.

Landing is scheduled at 11:31 p.m. MDT on Aug. 5. The department of physics and astronomy at the University of Utah will hold a Mars rover landing star party from 9:30 p.m. to 1:30 a.m. at the Language and Communication building, room 1100 at 255 Central Campus Drive.

Clark Planetarium will also have several Mars-related activities leading up to the landing.

E-mail: [email protected]