Allan Hills 84001 (ALH84001) is a fragment of a Martian meteorite that was found in the Allan Hills in Antarctica on December 27, 1984, by a team of American meteorite hunters from the ANSMET project. Like other members of the shergottitenakhlitechassignite (SNC) group of meteorites, ALH84001 is thought to have originated on Mars. However, it does not fit into any of the previously discovered SNC groups. Its mass upon discovery was 1.93 kilograms (4.3 lb).

In 1996, a group of scientists found features in the likeness of microscopic fossils of bacteria in the meteorite, suggesting that these organisms also originated on Mars. The claims immediately made headlines worldwide, culminating in then-U.S. president Bill Clinton giving a speech about the potential discovery. These claims were controversial from the beginning, and the wider scientific community ultimately rejected the hypothesis once all the unusual features in the meteorite had been explained without requiring life to be present. Despite there being no convincing evidence of Martian life, the initial paper and the enormous scientific and public attention caused by it are considered turning points in the history of the developing science of astrobiology.

The National Aeronautics and Space Administration (NASA ) is an independent agency of the U.S. federal government responsible for the civilian space program, as well as aeronautics and space research.NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA). The new agency was to have a distinctly civilian orientation, encouraging peaceful applications in space science. Since its establishment, most US space exploration efforts have been led by NASA, including the Apollo Moon landing missions, the Skylab space station, and later the Space Shuttle. NASA is supporting the International Space Station and is overseeing the development of the Orion spacecraft, the Space Launch System, Commercial Crew vehicles, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown management for uncrewed NASA launches.

NASA's science is focused on better understanding Earth through the Earth Observing System; advancing heliophysics through the efforts of the Science Mission Directorate's Heliophysics Research Program; exploring bodies throughout the Solar System with advanced robotic spacecraft such as New Horizons; and researching astrophysics topics, such as the Big Bang, through the Great Observatories and associated programs.