A NASA spacecraft that made the closest flyby ever of an asteroid apparently aimed its camera incorrectly and failed to get any close-ups of the giant orbiting rock, disappointing scientists yesterday.

The Deep Space 1 probe flew within about 10 miles of the Asteroid Braille, but the pictures it sent back back show only empty space, said Robert Nelson, project scientist at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

"This is analogous to mispointing a camera and getting a blank field of view," he said. "It's not very exciting if this hypothesis holds out."

The barrel-shaped, eight-foot spacecraft, launched in October and designed primarily to test technology for future deep-space flights, otherwise accomplished all of the objectives of the $152 million mission, NASA said.

And some science data still might be returned. An instrument that analyzes charged particles called ions appeared to be operating normally. Such data could help researchers determine the rock's makeup.

One of the tested technologies was a self-navigating system that lets the spacecraft set its own course. But the system lost sight of the asteroid with its camera about 20 minutes before the 35,000 mph encounter at 12:46 a.m. EDT yesterday, NASA said.

"This whole asteroid encounter was pure bonus," said deputy mission manager Marc Rayman. "The objectives of the mission had already been accomplished before the encounter -- that is, to test high-risk technologies for future missions."

Still, the blank pictures are disappointing to scientists, especially because so little is known about the thousands of asteroids that irregularly orbit the sun and sometimes collide with the planets. An asteroid that hit Earth 65 million years ago is believed to be responsible for the extinction of the dinosaurs.

The flyby took place more than 117 million miles from Earth, between Earth and Mars.

Among the other futuristic technologies tested was an ion propulsion engine that moved the spacecraft by sending out a stream of high-speed ions.

Ion engines deliver 10 times more thrust than a conventional engine for a given amount of fuel. That means spacecraft can be smaller, lighter and less expensive to launch into space.