page_title: List of European Space Agency programs and missions
section_title: Horizon 2000
hierarchical_section_title: List of European Space Agency programs and missions / Science programmes / Horizon 2000
caption_attribution_description: Artist’s impression of the Rosetta orbiter at comet 67P/Churyumov–Gerasimenko. The image is not to scale; the Rosetta spacecraft measures 32 m across including the solar arrays, while the comet nucleus is thought to be about 4 km wide. Credit: ESA–C. Carreau/ATG medialab
context_page_description: The European Space Agency operates a number of missions, both operational and scientific, including collaborations with other national space administrations such as the Japanese JAXA, the French CNES, the Italian ASI Agenzia Spaziale Italiana, the German DLR, the American NASA, and the Chinese CNSA. Their portfolio of missions also include many public-private partnership missions, a number of which with European satellite operators EUMETSAT, Eutelsat, and Inmarsat.
  A staple of the ESA's Science Doctrine is the Cosmic Vision programme, a series of space science missions chosen by the ESA to launch through competitions, similar to NASA's Discovery and New Frontiers programmes. It succeeds the Horizon 2000 and Horizon 2000+ programmes which launched notable missions such as Huygens, Rosetta and Gaia. Each space science mission are divided into two categories: "Sun and Solar System", missions studying the solar system, and "Astrophysics", missions studying interstellar astronomy.
context_section_description: Cornerstone missions
  Cornerstone 1 – SOHO, launched December 1995, operational – Joint ESA-NASA Solar observation mission providing real-time data for space weather forecasting.
  Cornerstone 1 – Cluster, launched June 1996, failed – Earth observation mission using four identical spacecraft to study the planet's magnetosphere. Failed on launch.
  Re-launch – Cluster II, launched July and August 2000, operational – Successful replacement mission.
  Cornerstone 2 – XMM-Newton, launched December 1999, operational – An X-ray space observatory, studying the full range of cosmic X-ray sources.
  Cornerstone 3 – Rosetta, launched March 2004, completed – 67P/Churyumov–Gerasimenko orbiter mission, studying comets and their evolution.
  Cornerstone 4 – Herschel, launched May 2009, completed – Infrared space observatory mission for general astronomy.
  Medium-sized missions
  Medium 1 – Huygens, launched October 1997, completed – Titan lander component of the Cassini–Huygens mission; first landing in the outer solar system.
  Medium 2 – INTEGRAL, launched October 2002, operational – Gamma ray space observatory, also capable of observing X-ray and visible wavelengths.
  Medium 3 – Planck, launched May 2009, completed – Cosmology mission that mapped the cosmic microwave background and its anisotropies.
caption: Artists' impression of Rosetta, a "cornerstone" mission of the Horizon 2000 program originally formulated in the 1980s.
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