Little did the Beatles know their metaphor would be taken literally one day. To the team behind NASA's Genesis mission, it has been years since they sent their "little darling," a small spacecraft with a wingspan of 22 feet (6.8 meters), out to collect and bring back a piece of the Sun.

"After more than two years of collecting solar wind ions, we're thrilled that the Genesis spacecraft is about to close up and come home," said Donald Sweetnam, Genesis project manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "On Thursday, April 1, we turn off the solar wind concentrator, stow the collector arrays, close the science canister cover, and lock it tight. The day after that, we will close the sample return capsule backshell and latch it in the configuration necessary for entry through Earth's atmosphere five months later on September 8."

Genesis is the agency's first sample return mission since the last Apollo mission in 1972, and the first ever to return material collected beyond the Moon. The science collection began November 30, 2001, with the opening of the spacecraft's science canister and the extension of special collector arrays to catch atoms from the solar wind. The atoms it has collected, believed to have preserved the composition of the solar nebula "cloud" from which our solar system developed, will help scientists better understand conditions in the distant past before Earth and other planets formed.

"Genesis will return a small but precious amount of samples leading to data that is crucial to our knowledge of the Sun and the formation of our solar system," said Genesis principal investigator Dr. Donald Burnett of the California Institute of Technology in Pasadena.

To help carry out its mission, Genesis has four dynamic instruments on board: bicycle-tire-sized solar-wind collector arrays, made of pure materials such as diamond, gold, silicon and sapphire, designed to entrap solar wind particles; an ion monitor to record the speed, density, temperature and approximate composition of the solar wind ions; an electron monitor to make similar measurements of electrons in the solar wind; and an ion concentrator to separate and focus elements of the solar wind like oxygen and nitrogen into special collectors.

"The science canister on the spacecraft contains the precious solar wind particles in their original state, protected from breakage and contamination with terrestrial matter during launch and recovery," Burnett said.

On May 2, 2004, the spacecraft will fly past Earth, positioning itself for daylight recovery. Four months later, the sample-return capsule will make a dramatic Earth entrance by parachuting toward the ground at the Utah Testing and Training Range of the U.S. Air Force. Specially trained helicopter pilots will catch the capsule in midair to prevent the delicate samples from being disturbed by the impact of a landing. The samples will then be preserved in a special laboratory at NASA's Johnson Space Center in Houston, and allocated for scientific study over the next century.

"Like all sample return missions, Genesis science really begins when the spacecraft phase of the mission ends," Burnett said. "It's been a long coming, but we can't wait to get to the analysis phase." Then, everything will be all right.