Atlas I

The production line of Atlas G, the predecessor to Atlas I, was wound down and eventually mothballed in the 1980s as the Space Shuttle came online. The Shuttle's promise of a rapid launch cadence and lower launch costs resulted in dwindling demand for Atlas, and expendable rockets as a whole. However, the Space Shuttle Challenger disaster in January 1986 caused second-guessing of the Shuttle's ability, and renewed interest in uncrewed expendable launch vehicles. Atlas G production would now be restarted, under the name Atlas I, sporting guidance upgrades. In June 1987, General Dynamics committed $100M to acquire long-lead procurement items to support the build of 18 vehicles for sale commercially. The "I" in "Atlas I" can cause confusion, as all previous Atlas rockets were designated using letters, ending with the Atlas H. However, subsequent rockets were designated using Roman numerals, starting with the Atlas II. Officially, the "I" is the Roman numeral "1". ==Design==

Atlas I was the last use of the classic Atlas design with three engines, a jettisonable booster section, and two vernier engines. While retaining most of those features, Atlas II replaced the verniers with a hydrazine roll control system. The payload mass numbers for Atlas I were based on vehicles flying with a -diameter Large fairing. If a vehicle flew using a Medium fairing, the lower mass of the fairing would enable an approximately increase in payload capacity to a geostationary transfer orbit. ==Launch history==