page_title: H-I
hierarchical_section_title: H-I
caption_attribution_description: English: NASA successfully launched more than 200 Earth-orbiting satellites, including Goddard's eighth Orbiting Solar Observatory aboard this Delta rocket on June 21,1975, at Cape Canaveral, Florida. The satellite-the final in a series of spacecraft specifically designed to look at the Sun in high-energy wavelength bands that scientists cannot see on Earth-gathered data on energy transfer in the Sun's hot, gaseous atmosphere and its 11-year sunspot cycle. Sunspots are cooler regions that appear as dark patches in the visible surface of the Sun and are more plentiful every 11 years. Flares and other powerful solar events that sometimes wreak havoc with Earth's communications systems also are associated with heightened sunspot activity. In addition to looking at the Sun, the satellite investigated celestial sources of X-rays in the Milky Way and beyond. It carried eight experiments.
context_page_description: The H–I or H–1 was a Japanese liquid-fuelled carrier rocket, consisting of a licence-produced American first stage and set of booster rockets, and all-Japanese upper stages. It was launched nine times between 1986 and 1992. It replaced the N-II, and was subsequently replaced by the H–2, which used the same upper stages with a Japanese first stage.
  The first stage of the H–I was a licence-built version of the Thor-ELT, which was originally constructed for the US Delta 1000 rocket. The stage had already been produced under licence in Japan for the N-I and N-II rockets. The second stage was entirely Japanese, using an LE-5 engine. On launches to Geosynchronous transfer orbits, a Nissan–built UM-69A solid motor was used as a third stage. Depending on the mass of the payload, either six or nine US Castor 2 SRMs were used as booster rockets.
context_section_description: The H–I or H–1 was a Japanese liquid-fuelled carrier rocket, consisting of a licence-produced American first stage and set of booster rockets, and all-Japanese upper stages. It was launched nine times between 1986 and 1992. It replaced the N-II, and was subsequently replaced by the H–2, which used the same upper stages with a Japanese first stage.
  The first stage of the H–I was a licence-built version of the Thor-ELT, which was originally constructed for the US Delta 1000 rocket. The stage had already been produced under licence in Japan for the N-I and N-II rockets. The second stage was entirely Japanese, using an LE-5 engine. On launches to Geosynchronous transfer orbits, a Nissan–built UM-69A solid motor was used as a third stage. Depending on the mass of the payload, either six or nine US Castor 2 SRMs were used as booster rockets.
caption: The American Thor-ELT was used for the H-I.
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