Satellites From Sputnik to MTG-I2: Instruments in Earth Orbit

Sputnik 1 was a 58-centimeter aluminum sphere with four radio antennas, launched by the Soviet Union on 4 October 1957. Its simple radio beeps could be heard by receivers worldwide, and it reentered and burned up on 4 January 1958, so the whole Space Age begins with a satellite that lasted only three months.

Explorer 1 was the first artificial satellite of the United States, launched at the end of January 1958 in response to Sputnik 1. Its instruments, designed by physicist James Van Allen, detected a band of charged particles trapped by Earth's magnetic field, which led to the Van Allen radiation belts. It stayed in orbit until it reentered over the Pacific Ocean on 31 March 1970.

LAGEOS, short for Laser Geodynamics Satellite, is a series of two research satellites. Each is a high density, passive laser reflector in a very stable medium Earth orbit, giving researchers a benchmark for laser ranging in studies of how the Earth moves. LAGEOS 1 launched on 4 May 1976 and the page lists the series as active.

Double Star was a joint mission of the China National Space Administration and the European Space Agency, and the first space mission China launched to investigate Earth's magnetosphere. Its two satellites, TC-1 on the equator and TC-2 over the poles, followed the European Cluster mission. Launched on 29 December 2003, it was extended twice and ran until the end of September 2007.

The Advanced Land Observing Satellite, also called Daichi, was a Japanese Earth observation satellite of about 3,810 kilograms, launched on 24 January 2006. After roughly five years in service it lost power and stopped communicating with ground controllers, though it remains in orbit, which makes it a lost satellite rather than a retired one.

The Greenhouse Gases Observing Satellite, called Ibuki, is the world's first satellite dedicated to monitoring greenhouse gases. Developed by the Japan Aerospace Exploration Agency and launched on 23 January 2009 from the Tanegashima Space Center, it measures carbon dioxide and methane at fifty six thousand locations, and Japanese agencies share the data with NASA and other scientific organizations.

LARES is a passive satellite system operated by the Italian Space Agency. Its first satellite, LARES 1, was launched into orbit on 13 February 2012, and like the LAGEOS satellites before it, it is described as passive.

ALOS-2, also called Daichi-2, is a Japanese satellite of about 2,120 kilograms launched in 2014. Unlike ALOS it has no optical cameras, which were removed to simplify construction and reduce costs. Its PALSAR-2 radar adds higher resolution spotlight modes to the ten meter survey mode, and it also carries the SPAISE2 ship identification system and a Compact Infrared Camera.

The Space Variable Objects Monitor, known as SVOM, is a small satellite carrying an X-ray telescope, launched on 22 June 2024. The China National Space Administration and the Chinese Academy of Sciences built it together with the French space agency CNES, and it is designed to study the explosions of massive stars, turning the path from Earth watching to sky watching.

MTG-I2, also known as Meteosat-14, is a European geostationary weather satellite and the second of four imaging satellites in the Meteosat Third Generation system, developed by EUMETSAT with the European Space Agency. Positioned at 9.5 degrees east, it is designed to image Europe in high resolution about every two and a half minutes, and it launched on an Ariane 62 in August 2026.