Phobos 1 was a failed uncrewed Soviet space probe of the Phobos Program, intended to explore Mars and its moon Phobos, launched in July 1988. The Phobos 1 probe failed on 28 August 1988 when a mistyped command deactivated important systems onboard the spacecraft. It was launched from Baikonur Cosmodrome aboard a Proton-K, with its twin probe Phobos 2. At 6,220 kg, they remained the heaviest interplanetary spacecraft until the 2011 Fobos-Grunt. The intent to carry out a mission with Phobos as the target was first made public 14 November 1984. Phobos was chosen as the target in order to avoid directly competing with previous American missions.

Wikipedia: https://en.wikipedia.org/wiki/Phobos_1. Original timeline Wikipedia link: https://en.wikipedia.org/wiki/Phobos_program. Related NASA reference: https://nssdc.gsfc.nasa.gov/planetary/chronology.html#1988. Description adapted from Wikipedia contributors (CC BY-SA 4.0; https://creativecommons.org/licenses/by-sa/4.0/).