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October 4, 1957 — ★ The Soviet Union launches Sputnik 1, the first artificial satellite; why it mattered: it shocked the United States and transformed spaceflight into a geopolitical contest. November 3, 1957 — The USSR sends Laika aboard Sputnik 2, making her the first animal to orbit Earth. January 31, 1958 — The United States launches Explorer 1, its first satellite, which helps discover the Van Allen radiation belts. July 29, 1958 — ★ President Dwight D. Eisenhower signs the National Aeronautics and Space Act; why it mattered: NASA centralized the U.S. civilian space program and coordinated the national response to Soviet advances. April 12, 1961 — ★ Yuri Gagarin becomes the first human in space and the first to orbit Earth aboard Vostok 1; why it mattered: the USSR demonstrated a decisive lead in crewed spaceflight. May 5, 1961 — Alan Shepard becomes the first American in space during the suborbital Mercury-Redstone 3 mission. May 25, 1961 — ★ President John F. Kennedy commits the United States to landing a person on the Moon before the decade’s end; why it mattered: the challenge gave the U.S. program a clear, ambitious objective. February 20, 1962 — John Glenn becomes the first American to orbit Earth aboard Friendship 7. June 16, 1963 — Valentina Tereshkova becomes the first woman in space, orbiting Earth aboard Vostok 6. March 18, 1965 — Alexei Leonov performs the first spacewalk during Voskhod 2. June 3, 1965 — Ed White conducts the first American spacewalk during Gemini 4. January 27, 1967 — ★ A cabin fire kills Apollo 1 astronauts Gus Grissom, Ed White, and Roger Chaffee; why it mattered: the disaster forced major redesigns and stricter safety procedures across Apollo. April 24, 1967 — Soviet cosmonaut Vladimir Komarov dies when Soyuz 1 crashes, exposing serious flaws in the USSR’s crewed lunar program. December 21–27, 1968 — ★ Apollo 8 carries humans around the Moon for the first time; why it mattered: it proved that the command module, nav