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Sea Star (satellite)
SeaStar, also designated OrbView-2, was an American commercial Earth-observation satellite operated by Orbital Sciences Corporation and launched in 1997, carrying SeaWiFS, a radiometer measuring ocean color for NASA research.
SELENE (Kaguya)
SELENE, nicknamed Kaguya, was a Japanese lunar orbiter mission by JAXA, launched in 2007 to study the Moon's origin and gravity field until its 2009 impact.
Self-replicating spacecraft
A self-replicating spacecraft, often called a von Neumann probe, is a hypothetical craft that harvests local materials to build copies of itself, enabling exponential exploration.
Semnan Space Center
Semnan Space Center, known as the Imam Khomeini Spaceport, is Iran's first permanent satellite launch site in Semnan province, launching Safir, Simorgh, and Zuljanah rockets.
Sentinel-1
Sentinel-1 is a two-satellite European radar Earth observation mission of the Copernicus program, launched from 2014, imaging Earth's surface day and night in all weather with C-band radar.
Sentinel-2
Sentinel-2 is a Copernicus Earth observation mission of pairs of identical satellites imaging Earth's land and coastal waters in 13 spectral bands every five days, with all data free.
Sentinel-3
Sentinel-3 is a European Earth observation satellite mission of the Copernicus program, developed by ESA and operated with EUMETSAT, measuring oceans, land, ice, and atmosphere; Sentinel-3A launched in 2016.
Sentinel-4
Sentinel-4 is a Copernicus Earth observation mission carrying a UVN spectrometer on the MTG-S1 satellite, launched in July 2025 to monitor European air quality hourly from geostationary orbit.
Sentinel-5P
Sentinel-5P, or Sentinel-5 Precursor, is a European Space Agency satellite launched in October 2017 from Plesetsk, Russia, carrying the TROPOMI instrument to map trace gases, aerosols, and ozone globally every day.
Sergei Korolev (Серге́й Па́влович Королёв)
Sergei Korolev (Сергей Павлович Королёв) was a Soviet rocket engineer who led the design of Sputnik 1 and Yuri Gagarin's 1961 spaceflight, known publicly only as the Chief Designer.
Sergei Krikalev (Сергей Константинович Крикалёв)
Sergei Konstantinovich Krikalev (Сергей Константинович Крикалёв) is a Russian cosmonaut born in 1958 who logged 803 days in space over six missions and held the cumulative spaceflight record until 2015.
Sergey Teteryatnikov
Sergey Aleksandrovich Teteryatnikov (born 1988) is a Russian test cosmonaut and former Navy submariner who flew to the International Space Station on SpaceX Crew-13 in October 2026.
Series 4000 (satellite bus)
The Series 4000 is a three-axis stabilized geostationary communications satellite bus introduced in 1985 by RCA Astro-Electronics, first flown on the Satcom K satellites and later adapted as the basis for GPS Block IIR navigation satellites.
Service module
A service module is the usually unpressurized portion of a spacecraft that carries the propulsion system, electrical power, and consumables such as propellant, oxygen, and water, and is jettisoned before re-entry.
SES (satellite constellation)
The SES satellite constellation is the multi-orbit fleet of communications satellites operated by SES S.A., a Luxembourg satellite operator, pairing geostationary satellites with the O3b medium Earth orbit system.
Sex in space
Sex in space, also called space sex, covers whether humans have had sex in orbit, which no astronaut has officially done, and how spaceflight affects reproduction.
SGP4
SGP4 (Simplified General Perturbations 4) is a computationally efficient orbit propagator that predicts the position and velocity of Earth-orbiting objects from Two-Line Element (TLE) sets.
Shavit
Shavit (שביט, "comet") is an Israeli three-stage solid-propellant launch vehicle built by Israel Aerospace Industries, used since 1988 to launch Ofeq reconnaissance satellites from Palmachim.
Shavit 2 (שביט 2)
Shavit 2 (שביט 2), Hebrew for Comet 2, is an Israeli three-stage solid-fuel rocket built by Israel Aerospace Industries, introduced in 2007 to launch Ofeq reconnaissance satellites from Palmachim Airbase.
Sheikh Muszaphar Shukor
Sheikh Muszaphar Shukor is a Malaysian orthopedic surgeon who became the first Malaysian citizen in space, spending nine days aboard the International Space Station in October 2007 under the Angkasawan Program.
Shenzhou
Shenzhou (神舟, "Divine Vessel") is China's crewed spacecraft, a three-module capsule that has carried every Chinese astronaut into orbit since the country's first human spaceflight in 2003.
Shenzhou (神舟) (spacecraft)
Shenzhou (神舟), meaning "Divine Vessel," is China's independently developed crewed spacecraft, a three-module vehicle first flown in 1999 that has carried crews to the Tiangong space station since 2021.
Shenzhou 12 (神舟十二号)
Shenzhou 12 (神舟十二号) was a Chinese crewed spacecraft mission that launched three astronauts to the Tiangong space station's Tianhe module in June 2021 for a 90-day stay.
SHERLOC (spectrometer)
SHERLOC (Scanning Habitable Environments with Raman and Luminescence for Organics and Chemicals) is a spectrometer on NASA's Perseverance rover, which landed in Jezero Crater, Mars, in 2021 to map organic matter and minerals.
Shi Jian
Shi Jian (实践, "Practice") is a Chinese satellite series for scientific and technology testing, flown since 1971 and known for debris removal and refueling demonstrations.
Shiyan
Shiyan (试验, "experiment") is the designation China applies to a series of experimental satellites, launched since 2004 to test new spacecraft technologies and instruments, often with undisclosed payloads.
Shubhanshu Shukla (शुभांशु शुक्ला)
Shubhanshu Shukla (शुभांशु शुक्ला) is an Indian Air Force officer and ISRO astronaut who piloted Axiom Mission 4 in 2025, becoming the first Indian to visit the International Space Station.
Shuttle Carrier Aircraft
The Shuttle Carrier Aircraft (SCA) were two modified Boeing 747s, NASA 905 and NASA 911, used from 1977 to 2012 to ferry Space Shuttle orbiters piggyback.
Shuttle Landing Facility
The Shuttle Landing Facility is an airport at NASA's Kennedy Space Center in Florida, built in 1974 to land the Space Shuttle and now operated commercially by Space Florida.
Shuttle-C
Shuttle-C was a proposed unmanned, expendable heavy-lift launch vehicle NASA studied in the late 1980s and early 1990s, using Space Shuttle hardware with a cargo carrier in place of the orbiter.