This is NASA's Low-Density Supersonic Decelerator, "a rocket-powered, saucer-shaped test vehicle" designed to land huge payloads on Mars. So there — suck on that Martians, because after all these decades of sci-fi invasions, we are going to be the ones seizing your planet with our very own flying saucers.
The new LDSD — designed and built by engineers at the Jet Propulsion Laboratory in Pasadena, California — will be crucial for future human exploration on the Red Planet. This platform will allow us to deliver the supplies needed for long-term missions. To test it, however, we will need to take it first to the upper layers of Earth's stratosphere, where conditions are similar to Mars.
During the June experimental flight test, a balloon will carry the test vehicle from the Hawaii Navy facility to an altitude of about 120,000 feet [36,576m]. There, it will be dropped and its booster rocket will quickly kick in and carry it to 180,000 feet [54,864m], accelerating to Mach 4. Once in the very rarefied air high above the Pacific, the saucer will begin a series of automated tests of two breakthrough technologies.
The low-resolution images from the saucer are expected to show the vehicle dropping away from its high-altitude balloon mothership and then rocketing up to the very edge of the stratosphere. The test vehicle will then deploy an inflatable Kevlar tube around itself, called the Supersonic Inflatable Aerodynamic Decelerator (SIAD). After the SIAD inflates, the test vehicle will deploy a mammoth parachute called the Supersonic Disk Sail Parachute.
NASA will test the on June 3, at the Navy's Pacific Missile Range Facility. Mark the day in your calendars, because this is going to be a great show to watch on the Internet. More about the LDSD here.