A team NASA and university researchers are eagerly awaiting the upcoming launch of MESSENGER, the first space probed aimed at the planet Mercury in three decades.

Researchers said the mission, set to launch Aug. 2 from Florida's Cape Canaveral, will not only provide the best look yet at the moon-sized Mercury, but also represents a potential watershed for scientists hoping to understand the fundamental processes behind planet formation in our solar system.

"We've wanted to have a Mercury orbiter mission for more than 30 years but didn't know how to do it," said spacecraft payload manager Robert Gold, of the Johns Hopkins University Applied Physics Laboratory (JHUAPL), during a telephone interview. "Mercury is one of the closer planets, but it's one we know very little about."

MESSENGER, short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging mission, is designed to orbit Mercury for at least one year, snapping images of the entire surface and probing its depths with seven instruments to determine the planet's chemical and physical composition. The mission is a collaborative effort between NASA, JHUAPL and the Carnegie Institution of Washington.

The closest planet to the Sun, Mercury has stumped planetary scientists trying to understand why it has a density close to that of Earth but a size just larger than our planet's moon. NASA's Mariner 10 spacecraft swung by the planet three times between 1974 and 1975, taking pictures less than half of the planet. But that mission discovered Mercury's magnetic field, and scientists now know the planet has a gossamer thin atmosphere to boot.

"Mariner 10 left us with more questions than answers," said NASA's Orlando Figueroa, director the agency's solar system exploration division, during a mission briefing today at NASA headquarters. "Now we have a much more capable mission to help us understand Mercury."

It should take MESSENGER more than six and a half years to make the tricky voyage to Mercury, requiring no less than a flyby of Earth, two past Venus and three past Mercury itself before the spacecraft slides into orbit in 2011. Upon arrival, the spacecraft will orbit within 125 miles (300 kilometer) of Mercury's surface.

Among the prime questions plaguing Mercury-minded scientists lie under the small planet's crust. Despite its small size, Mercury's density and magnetic field are comparable to Earth's. The planet is thought to be composed of mostly metal, but scientists aren't sure how large its core is and whether a spinning liquid outer core is the powerhouse behind its robust magnetic field.

Mercury, in short, is more mysterious than its cousins, Venus, Earth and Mars.

"The inner planets are roommates, if you will, and yet Mercury turned out pretty different," said Sean Solomon, principal scientist at the Carnegie Institution of Washington, during the mission briefing. "It's possibly that Mercury started out more Earth-like in appearance, but lost its rocky covering due to he extreme heat from the Sun."

Mercury may have also formed in a region near the Sun that was simply richer in metals, which would shed clues on the composition and distribution of materials in the early solar system, researchers said.

One of the biggest mysteries Solomon hopes MESSENGER will solve is the composition of material deposits at Mercury's poles. Data from ground-based radar observations, he added, suggest that material has the characteristics of water ice and sits in polar craters that never see sunlight due to Mercury's almost total lack of tilt.

"An alternative to water ice is the element sulfur," Solomon said, adding that there are a few competing ideas over what the polar material actually is. "We want to test [those ideas] by looking at what's down in those craters."

Gold told SPACE.com the main reason it's taken 30 years to send another mission to Mercury - an orbiter, no less - is because of the harsh environment a spacecraft must endure while studying the planet.

MESSENGER will have to endure temperatures of more than 800 degrees Fahrenheit (426 degrees Celsius), though a ceramic cloth sunshade will bear the brunt of the heat. Under the safety of its shade, MESSENGER should plod along at a comfortable room temperature.

"But the solar panels have to operate at those full temperatures," Gold said, adding that engineers had to space out solar cells between mirrors on MESSENGER's solar panels to reflect enough sunlight to keep the array cool and functioning.

The spacecraft itself if built of a carbon-fiber structure to maintain integrity, and carries as much miniaturized technology as possible, a critical element for a spacecraft whose voyage demands that half of its flight mass is taken up by fuel. MESSENGER weighs a total of 2,442 pounds (1,100 kilograms), 1,323 pounds (600 kilograms) of which is fuel.

"Fortunately, the technologies are now available to make this mission," Gold said. "What I really expect to come out of this is an entire new set of knowledge, not just for Mercury, but really the whole solar system."