A pilotless NASA aircraft is set to overfly Hurricane Earl on Thursday, in a scientific first to gather data about the potentially-deadly storm front bearing down on the US east coast.

After taking off from Edwards Air Force base in California, the converted Global Hawk drone plane will use a battery of instruments to study how hurricanes develop into awesome forces of nature.

"This is a real adventure for this airplane," said Commander Phil Hall, who will remotely control the plane from the military base near Los Angeles on the US West Coast.

"Going over a hurricane, for any airplane, is a bit risky, and we are kind of breaking a new frontier with this flight," he told AFP.

Thousands of people have evacuated North Carolina's barrier islands as Hurricane Earl threatened to pound large areas of the US East Coast with heavy winds and rough seas.

The strongest Atlantic storm of 2010 was on a path to lash the North Carolina coast and then move north, wreaking havoc on the end-of-summer US Labor Day holiday weekend that usually draws millions to the beaches.

The Global Hawk proved its mettle last week when it overflew Tropical Storm Frank off the coast of Mexico -- but Earl, with speeds of up to 140 miles (220 kilometers) per hour, is in a different league.

Originally built to take photos for military reconnaissance missions, the aircraft "is not designed for turbulence or for bad weather," Hall said.

"We have to take a lot of extra steps to make sure we don't exceed the performances of the aircraft... But we have a very good vibration system. So if we get that kind of turbulence, we'll know right away."

The plane may be fragile, but NASA is expecting a lot from it. The space agency's three aircraft are part of its Genesis and Rapid Intensification Processes (GRIP) hurricane research mission.

The NASA mission aims to learn more about why and how storms gain or lose power, growing into mighty hurricanes or fizzling out to mere strong winds, over the course of sometimes only a few hours.

"Certainly there are many good tools already on other airplanes but this one allows us to develop satellite-like instruments," said Gerry Heymsfield, a NASA research meteorologist.

"We are trying to understand what does lead to the intensification of the storms, because if we can understand some of these processes, we will be allowed to forecast better."

One key asset of the Global Hawk is that it can stay continuously aloft for 30 hours.

"We can take this airplane from here, in California, to the North Pole, and about 10 hours after, come back here in one flight," said Hall. "That's why this aircraft has capabilities that are so interesting to scientists."

In the near future, NASA hopes to move the planes' base to the East Coast -- closer to where many storms develop over the Atlantic -- to make even better use of its long flight time.

The GRIP program will notably give NASA a better understanding of how sand and dust from Africa's Sahara desert feed into storms.

"The general theory is that Saharan dust inhibits the formation of storms. But it's not always the case," said Heymsfield.

"The big picture is to help improve the forecast. So for the public, it allows us to increase safety and warnings," added Hall.