# Hipparcos > scientific satellite of the European Space Agency **Wikidata**: [Q555846](https://www.wikidata.org/wiki/Q555846) **Wikipedia**: [English](https://en.wikipedia.org/wiki/Hipparcos) **Source**: https://4ort.xyz/entity/hipparcos ## Summary Hipparcos was a space telescope. ## Summary Hipparcos (High Precision Parallax Collecting Satellite) was a scientific satellite operated by the European Space Agency (ESA) from 1989 to 1993. It was designed to measure the precise positions, distances, and motions of stars, significantly advancing astronomical research. ## Key Facts - **Launch Date**: August 8, 1989, aboard an Ariane 44LP rocket from ELA-2. - **Operator**: European Space Agency (ESA). - **Mass**: 1,140 kg at launch, 635 kg dry. - **Payload Mass**: 210 kg. - **Diameter**: 29 cm. - **Orbit**: Geostationary orbit. - **Orbital Period**: 628.9 minutes. - **Named After**: Ancient Greek astronomer Hipparchus. - **Successor**: Followed by the Gaia mission. - **Service Retirement**: August 15, 1993. - **Manufacturer**: Alenia Spazio and Matra Marconi Space. - **Launch Contractor**: Arianespace. ## FAQs ### Q: What was Hipparcos' primary mission? A: Hipparcos was designed to create the most accurate three-dimensional map of the Milky Way by measuring the positions, distances, and motions of stars with unprecedented precision. ### Q: How did Hipparcos differ from its predecessor? A: Unlike its predecessor, Hipparcos was the first space mission dedicated solely to astrometry, focusing on high-precision measurements of stellar positions and parallaxes. ### Q: What was the significance of Hipparcos' data? A: Hipparcos' data provided a catalog of over 100,000 stars, significantly improving our understanding of stellar distances and motions, which remains foundational for modern astronomy. ### Q: Why was Hipparcos retired? A: Hipparcos was retired in 1993 after completing its primary mission, as its data was sufficient for the time and the ESA prioritized newer projects like Gaia. ### Q: How did Hipparcos contribute to astronomy? A: Hipparcos revolutionized astrometry by demonstrating the feasibility of space-based high-precision stellar measurements, paving the way for future missions like Gaia. ## Why It Matters Hipparcos was a groundbreaking mission in the field of astrometry, the precise measurement of the positions and movements of stars. Launched by the European Space Agency in 1989, it was the first space mission dedicated solely to this purpose. The satellite measured the positions, distances, and motions of over 100,000 stars with unprecedented accuracy, creating a three-dimensional map of the Milky Way. This data significantly advanced our understanding of stellar physics, galactic structure, and the dynamics of the cosmos. Hipparcos' success demonstrated the feasibility of high-precision astrometry from space, influencing the design of subsequent missions like the Gaia spacecraft. Its legacy endures in the foundational datasets it provided, which remain essential for modern astronomical research. ## Notable For - **First Space-Based Astrometry Mission**: Hipparcos was the first mission to focus exclusively on measuring stellar positions and parallaxes from space. - **High Precision Measurements**: It achieved an accuracy of 0.001 arcseconds, a significant improvement over ground-based observations. - **Catalog of 100,000 Stars**: Hipparcos compiled one of the most comprehensive stellar catalogs of its time, revolutionizing our understanding of the Milky Way. - **Pioneering Technology**: The mission demonstrated the feasibility of space-based high-precision astrometry, influencing future missions like Gaia. - **International Collaboration**: Hipparcos involved contributions from multiple European countries, showcasing international cooperation in space science. ## Body ### Mission Overview Hipparcos (High Precision Parallax Collecting Satellite) was a scientific satellite operated by the European Space Agency (ESA) from 1989 to 1993. Its primary objective was to measure the precise positions, distances, and motions of stars, significantly advancing astrometry, the branch of astronomy concerned with the positions and movements of celestial objects. ### Launch and Operation Hipparcos was launched on August 8, 1989, aboard an Ariane 44LP rocket from the European Spaceport in Kourou, French Guiana. The satellite was placed in a geostationary orbit, allowing continuous observation of the same region of the sky. Its operational lifespan was initially planned for four years, but it was retired on August 15, 1993, after completing its primary mission. ### Design and Specifications Hipparcos had a mass of 1,140 kg at launch and 635 kg dry, with a payload mass of 210 kg. Its diameter was 29 cm, and it had a nominal power output of 295 watts. The satellite was manufactured by Alenia Spazio and Matra Marconi Space, with Arianespace serving as the launch contractor. ### Scientific Contributions Hipparcos measured the positions of over 100,000 stars with an accuracy of 0.001 arcseconds, creating a three-dimensional map of the Milky Way. This data significantly improved our understanding of stellar distances, motions, and the structure of the galaxy. The mission's success demonstrated the feasibility of high-precision astrometry from space, influencing the design of subsequent missions like Gaia. ### Legacy and Impact Hipparcos' legacy endures in the foundational datasets it provided, which remain essential for modern astronomical research. Its contributions to astrometry have been instrumental in advancing our understanding of the cosmos, and it serves as a model for future space-based astronomical missions. The mission's success underscores the importance of international collaboration in space science and the pursuit of high-precision astronomical measurements. ## References 1. Jonathan's Space Report 2. Freebase Data Dumps. 2013