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Luminescence dating estimates when mineral grains were last exposed to sunlight or heat. It is widely used on sediments, fired materials, and some rock surfaces where quartz or feldspar crystals stored energy from natural radiation after burial.
Uranium-thorium dating is a radiometric method used to date calcium carbonate materials such as speleothems and corals. By measuring uranium and thorium isotopes, scientists can build chronologies for cave deposits, reefs, sea-level change, and late Quaternary climate records.
Speleothems are mineral deposits that form inside caves, including stalactites, stalagmites, flowstone, columns, and cave popcorn. Beyond their striking shapes, some speleothems preserve layered records of groundwater chemistry, rainfall, vegetation, and past climate.
Radiocarbon dating estimates the age of once-living materials by measuring carbon-14, a radioactive isotope that decays after an organism stops exchanging carbon with the environment. It transformed archaeology, geology, climate science, and the study of recent Earth history.
Ice cores are cylinders of ice drilled from glaciers, ice caps, and ice sheets. Their layers, trapped air bubbles, dust, ash, chemistry, and isotopes preserve information about past atmosphere, snowfall, temperature, volcanic eruptions, pollution, and climate change.
Dendrochronology is the science of dating and interpreting annual growth rings in trees. By matching ring patterns across many samples, researchers can assign calendar years to wood and reconstruct past climate, fires, floods, insect outbreaks, earthquakes, building dates, and environmental change.
Epistasis is a genetic interaction in which the effect of one gene depends on one or more other genes. It helps explain why traits are often shaped by networks of genes rather than by single genes acting alone.
Endosymbiotic theory explains how key parts of eukaryotic cells, especially mitochondria and chloroplasts, originated from bacteria that became long-term partners inside other cells. It is one of biology's clearest examples of evolution through cooperation as well as competition.
RNA interference, often shortened to RNAi, is a gene-silencing system in which small RNA molecules guide protein complexes to matching RNA targets. It helps cells regulate genes, defend against some genetic threats, and gives researchers a precise way to reduce the expression of selected genes.
Bioremediation uses living organisms or their biological processes to break down, transform, immobilize, or remove pollutants from contaminated soil, groundwater, sediments, sludge, and waste. It can be powerful, but it depends on the contaminant, site conditions, biology, time, monitoring, and cleanup goals.
Protein folding is the process by which a chain of amino acids settles into the three-dimensional shape that lets a protein do its job. Folding connects genetic instructions to working molecules, and mistakes in folding can affect cell health, medicine, biotechnology, and our ability to design new proteins.
The J-2 engine was a liquid-hydrogen and liquid-oxygen rocket engine used on the upper stages of Saturn launch vehicles.
The F-1 engine was the large kerosene-and-liquid-oxygen rocket engine that powered the first stage of NASA's Saturn V launch vehicle.
Saturn V was the three-stage heavy-lift rocket NASA used to send Apollo crews toward the Moon and launch Skylab into orbit.
Direct ascent is a lunar mission architecture in which one spacecraft lands on the Moon and returns to Earth without orbital rendezvous.
Earth orbit rendezvous is a mission architecture in which spacecraft elements meet in Earth orbit before leaving for the Moon or another destination.
Lunar orbit rendezvous is the mission architecture that let Apollo land a small lunar module on the Moon while the command and service module stayed in lunar orbit.
Powered descent initiation is the start of a lunar lander's main engine burn from low approach orbit toward the surface.
Descent orbit insertion is the maneuver that lowers a lunar landing spacecraft from a safe orbit into a lower approach path before powered descent.
Lunar orbit insertion is the braking maneuver that slows a Moon-bound spacecraft enough for the Moon's gravity to capture it into orbit.
Trans-Earth injection is the maneuver that sends a spacecraft away from the Moon or another body onto a return trajectory toward Earth.
Trans-lunar injection is the engine burn or maneuver that sends a spacecraft out of Earth orbit and onto a trajectory toward the Moon.
A free-return trajectory is a spacecraft path that can loop around the Moon or another body and naturally return to its starting planet if no major engine burn occurs.
A near-rectilinear halo orbit is a stretched lunar halo orbit that passes close to the Moon at one end and far from it at the other, making it useful for cislunar mission planning.
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