Lisa's First Word promotion due to the 1984 Summer Olympics boycott by the Soviet Union, as happened to Krusty. At one point in the episode, Dr. Hibbert refers to Olympic gymnastic medalist Mary Lou Retton. In its original American broadcast, "Lisa's First Word" was watched by 28.6 million viewers, the most-watched episode of the season. It finished thirteenth in the ratings for the week of November 30 to December 6, 1992, with a Nielsen rating of 16.6. The episode was the highest-rated show on Fox that week. It acquired the highest national Nielsen rating of the show since the season two episode "Bart
Liquid apogee engine be prohibited or restricted in the near- to mid-term. Exemptions are being sought to allow to be used for space applications, however to mitigate this risk, companies are investigating alternative propellants and engine designs. A change over to these alternative propellants is not straightforward, and issues such as performance, reliability and compatibility (e.g. satellite propulsion system and launch-site infrastructure) require investigation. The performance of an apogee engine is usually quoted in terms of vacuum specific impulse and vacuum thrust. However, there are many other details which influence performance: A typical 500 N-class hypergolic liquid apogee engine has a vacuum specific