NASA's $2.5 billion Curiosity rover isn't set to touch down on Mars until Aug. 5, after a 354-million-mile journey that began inside a rocket last November, but its creators are already biting their nails in anticipation of the extraordinarily tricky landing. The odds aren't great: 60 percent of NASA's missions to the surface of the red planet have fallen apart. NASA experts have dubbed Curiosity's planned descent "seven minutes of terror," and just released a blockbuster new video explaining the obstacles that the car-sized mobile lab must overcome. (Watch the rather heart-pounding clip below.) Here, a guide:

Remind me: What exactly is the Curiosity?
It's NASA's biggest and most advanced mobile space lab yet. The 10-foot-long, 9-foot-wide Curiosity is charged with determining whether microbial alien life ever lived on Mars' desert-like expanses. 

Why is its landing so treacherous?
The spacecraft has "literally seven minutes to get from the top of the atmosphere to the surface of Mars," says NASA engineer Tom Rivellin, "going from 13,000 miles an hour to zero, in perfect sequence, perfect choreography, perfect timing." The entire process is pre-programmed, meaning scientists can't just fire up a remote control to change course, as radio signals would need 14 full minutes to traverse the distance between Earth and Mars.

How will Curiosity slow down?
The automated landing has four main steps, says Amy Hubbard at the Los Angeles Times. Step one is the initial entry: The spacecraft will use its heat shield to withstand temperatures as high as 1,600 degrees Fahrenheit as it enters Mars' atmosphere and begins to slow down. Step two involves opening a gigantic supersonic parachute, which pops out while the craft is still traveling at Mach 1.7 — nearly twice the speed of sound. 

Then what happens?
Step three: Curiosity shoots out of the heat shield. Eight reverse rockets also begin blasting to slow the rover's descent even more, until the mobile lab is left hovering above the ground. Then there's step four: The "sky crane maneuver," which lowers the one-ton rover to the ground with a tether. "Hundreds and hundreds of events need to go just right during that seven minutes," scientist Ashwin R. Vasavada tells the Los Angeles Times. "Computer glitches, stuck valves, software bugs, and even surprises from Mars itself" — they could all ruin the entire mission. The whole thing looks near impossible, says Hubbard. You can't help but think: "It's not going to work."

See for yourself:

Sources: ABC NewsLos Angeles TimesNational GeographicWired