The wispy atmosphere of Mars is 99 percent thinner than Earth's -- not great for slowing down space ships or metorites. NASA's testing a way to make it work, however, using a helium balloon, rockets and a Low Density Supersonic Decelerator (LDSD) vehicle, which looks suspiciously like a UFO. The plan is to launch the LDSD to 120,000 feet using the balloon, then push it to the edge of space (180,000 feet) with the powerful solid-fueled rocket. At that point it'll be traveling hypersonically at Mach 4 in the stratosphere, simulating a Mars arrival. A second, donut-like balloon called the "supersonic inflatable aerodynamic decelerator" will then deploy, increasing the craft's surface area and slowing it to about Mach 2.5. Finally, the largest supersonic parachute ever tested will pop, allowing the vehicle to eventually touch down in the ocean. If the complex plan goes awry, NASA will learn from the data it gathers and try again in order to meet its ambitious Mars exploration schedule. Either way, it'll be fun to watch -- the launch is set for tomorrow in Hawaii between 2:00 and 3:30 PM ET.