NASA scientists have joined the search for the elusive ivory-billed woodpecker, long thought to be extinct but recently sighted in Arkansas.

NASA used a laser-equipped research aircraft to fly over the Big Woods area of the Mississippi Delta to learn more about the big woodpecker's potential habitat, the U.S. space agency said on Thursday.

Scientists from NASA's Goddard Space Flight Center and the University of Maryland used an instrument that sends pulses of energy to Earth's surface, where light particles from the lasers bounce off leaves, branches and the ground and reflect back to the instrument.

These signals give scientists a direct measurement of the height of the forest's leaf-covered treetops, the ground level below and everything in between, NASA said in a statement.

"We're trying to understand the environment where these birds live or used to live," said Woody Turner, a NASA scientist.

Knowing the thickness of ground vegetation, the density of tree leaves and other factors including closeness to water and age of the forest might help in the search, he said.

NASA's aerial effort is part of a quest that began in 2004 after a kayaker reported spotting the woodpecker along the Cache River in Arkansas. Before that, there had been no confirmed sightings of ivory-bills for half a century.

Bird experts have searched on the ground, looking for nesting spots, leaving remote-controlled cameras and audio recorders in places that seem likely habitats for the woodpecker. But so far they have captured no confirmed images or sound recordings of the creature.

In 2005, researchers published a report in the journal Science that at least one male ivory-bill still survived, but this finding has been challenged.

The NASA-University of Maryland project aims to give detailed information about the bird's habitat to searchers on the ground, who can use it starting this fall to look for new evidence of the ivory-billed woodpecker's possible survival.