All articles starting with S
44,216 articles
Spacewatch
Spacewatch is a University of Arizona research group, founded by Tom Gehrels and Robert McMillan in 1980, that observes asteroids and comets, especially near-Earth objects, from telescopes at Kitt Peak, Arizona.
SpaceWire
SpaceWire is a European spacecraft data-handling network standard developed under ESA auspices and standardized in 2003, used by NASA, JAXA, and Roscosmos missions including JWST and BepiColombo.
SpaceX
SpaceX, formally Space Exploration Technologies Corp., is an American spaceflight company founded by Elon Musk in 2002, now the dominant orbital launch provider and Starlink operator.
SpaceX acquisition of Anysphere
The SpaceX acquisition of Anysphere was a $60 billion all-stock purchase of Anysphere, maker of the Cursor AI coding assistant, agreed in June 2026 and completed that August.
SpaceX acquisition of xAI
The SpaceX acquisition of xAI was a February 2026 all-stock merger in which Elon Musk's SpaceX bought the Grok maker at a $250 billion valuation.
SpaceX Crew-1
SpaceX Crew-1, also known as USCV-1, was the first operational Commercial Crew mission, flying NASA and JAXA astronauts to the International Space Station from November 2020 to May 2021.
SpaceX Crew-11
SpaceX Crew-11 was the 11th SpaceX crew rotation mission to the International Space Station, flying four astronauts aboard the Crew Dragon Endeavour from August 2025 to January 2026.
SpaceX Crew-12
SpaceX Crew-12 was a 2026 NASA Commercial Crew mission to the International Space Station, carrying Jessica Meir, Jack Hathaway, Sophie Adenot, and Andrey Fedyaev for 237 days in orbit.
SpaceX Crew-13
SpaceX Crew-13 is the thirteenth SpaceX crew rotation mission to the International Space Station, launched for NASA on October 1, 2026 with four astronauts from three space agencies.
SpaceX Crew-9
SpaceX Crew-9 was a 2024 NASA Commercial Crew mission to the International Space Station that returned Boeing Starliner astronauts Butch Wilmore and Suni Williams to Earth in 2025.
SpaceX Dragon
SpaceX Dragon, also known as the Dragon spacecraft, is a reusable SpaceX capsule that carries cargo and astronauts to the International Space Station atop Falcon 9 rockets.
SpaceX Dragon 2
SpaceX Dragon 2, also called Crew Dragon, is a reusable SpaceX spacecraft that carries astronauts and cargo to the International Space Station, certified by NASA in 2020.
SpaceX IPO and Colossus compute revenue
SpaceX's June 2026 IPO, the largest in history, revealed more than $76 billion of contracted AI compute rent through 2029, mostly from Anthropic and Google, sparking a bubble debate.
SpaceX Merlin
The SpaceX Merlin, also known as the Merlin 1, is a family of kerosene and liquid oxygen rocket engines powering the Falcon 1, Falcon 9, and Falcon Heavy.
SpaceX Raptor
The SpaceX Raptor, or Raptor engine, is a liquid oxygen and liquid methane rocket engine developed by SpaceX, powering the Super Heavy booster and Starship upper stage.
SpaceX reusable launch system development program
The SpaceX reusable launch system development program is SpaceX's effort begun in the early 2010s to recover and re-fly rockets, achieving the first orbital booster landing in December 2015.
SpaceX rocket engines
SpaceX rocket engines are the liquid-propellant engines developed in-house by SpaceX to power the Falcon 1, Falcon 9, Falcon Heavy, and Starship rockets and the Dragon spacecraft.
SpaceX Starbase
SpaceX Starbase, also known as Boca Chica spaceport, is SpaceX's Starship launch, test, and manufacturing complex at Boca Chica, Texas, incorporated as a city in May 2025.
SpaceX Starbase, Louisiana
SpaceX Starbase, Louisiana, is a planned commercial spaceport announced in 2026 on 125,000 acres of Pecan Island in Vermilion Parish, backed by a $100 billion investment.
SpaceX Starfall
SpaceX Starfall, also called Project Starfall, is SpaceX's uncrewed, mass-producible reentry capsule for carrying payloads to orbit and returning them to Earth, first flown in 2026.
SpaceX Starshield
SpaceX Starshield is SpaceX's government-oriented satellite business built on Starlink technology, offering Earth observation, communications, and hosted payloads, including a classified reconnaissance constellation for the National Reconnaissance Office.
SpaceX Starship
SpaceX Starship, also called the Starship and Super Heavy, is a fully reusable two-stage super-heavy-lift rocket developed by SpaceX at Starbase, Texas, and selected by NASA for the Artemis lunar landings.
SpaceX Starship design history
The SpaceX Starship design history traces the fully reusable Super Heavy booster and Starship spacecraft from 2012 Mars studies through the ITS, BFR, and V3 vehicles.
Spacing effect
Spacing effect (distributed practice, spaced repetition): long-term memory improves when study sessions are separated in time rather than massed. First studied by Ebbinghaus (1885); meta-analyses show moderate effects (d ≈ 0.46–0.85) across classroom, language, math, and medical learning.
Spacing Guild
Spacing Guild: fictional Dune organization holding a monopoly on interstellar travel via spice-mutated Navigators with limited prescience guiding Heighliners through foldspace; one leg of the Great Convention tripod, later broken by Ixian navigation machines.
SpaCOVID trial
The SpaCOVID trial was a completed randomized clinical trial at Comenius University in Bratislava testing mountain spa rehabilitation, with or without ubiquinol, for post-COVID-19 syndrome.
spaCy
spaCy is an open-source natural language processing library for Python and Cython, first released in 2015 by Explosion, with pretrained pipelines supporting tagging, parsing, and named entity recognition in over 70 languages.
SPAD (railway)
A signal passed at danger (SPAD) is an event in which a train passes a stop signal without authority, prompting automatic train protection systems to reduce the risk.
Spade
A spade is a digging tool with a flat blade and straight, sharp edge for cutting soil and roots, distinct from the shovel, which lifts loose material.
Spades (card game)
Spades is an American trick-taking card game invented in the 1930s, likely in the Midwest, with spades permanently trump. Four-player partnership play, nil bids, bags, and 500-point scoring distinguish it from bridge and whist.