Throughout the annals of American space exploration, a select few spacecraft have had the distinction of carrying human beings beyond Earth.

Next week, Boeing is poised to join this elite group with the long-awaited launch of its Starliner capsule, just the sixth class of vessel built in the United States for NASA astronauts.

Here's a recap of their storied past, marked by groundbreaking triumphs and some devastating setbacks.

Mercury

Known as America's "man-in-space" program, Project Mercury was born just days after NASA itself was formed in 1958, and officials settled on the term "astronauts" for its space explorers.

On May 5, 1961, Alan Shepard became the first American to fly in space during a 15-minute suborbital flight in the one-man, cone-shaped capsule—about a month after the Soviet Union's Yuri Gagarin became the first human to achieve the feat.