Pasadena, Calif. ? A spacecraft is on track to fly through the tail of a comet on Friday, collecting hundreds of specks of the primitive material from which the sun, the planets and all living creatures are made, NASA said.

The National Aeronautics and Space Administration’s Stardust spacecraft is expected to pass within 186 miles of the comet Wild 2 as it catches the shimmering gas and dust cloud that envelops the dirty ball of ice and rock.

The unmanned probe should make its closest approach at 1:40 p.m. CST Friday, when the comet and probe will be 242 million miles from Earth, mission members said Tuesday at NASA’s Jet Propulsion Laboratory.

During the flyby, Stardust should capture hundreds if not thousands of particles of dust ripped from Wild 2 (pronounced Vilt-2) by streams of gases boiled from the comet’s surface by the warming rays of the sun.

NASA also expects the spacecraft to take 72 black-and-white pictures of the comet’s 3.3 mile-diameter nucleus. The first of those images could be received on Earth as early as Friday afternoon.

Scientists are eager to study the particles since they represent pristine examples — preserved for 4.6 billion years by the cold of space — of the material that coalesced to form our solar system and everything in it. Stardust should sweep up much less than a thimbleful of the material.

The scientists believe the dust contains many of the organic compounds necessary for life.

Comets that pelted the Earth long ago could have delivered those molecules.