August 21, 1993 - Mars Probe Disappears - Never To Be Found...
1993: NASA loses contact with the Mars Observer, a scientific probe sent to study the geology and climate of the red planet. Contact with the craft is never re-established, and the reasons for its disappearance remain a mystery.
The Mars Observer, launched on Sept. 25, 1992, was supposed to be the first of a three-probe series for NASA's Planetary Observer project -- the others were bound for Mercury and the moon -- but its failure resulted in scrubbing the other two missions.
Contact was lost with the Mars Observer only three days before it was to enter its Martian orbit.
Had the spacecraft attained a successful orbit, the primary objectives for the mission included determining the elemental makeup of the Martian surface, studying the planet's magnetic and gravitational fields, establishing the nature of its atmospheric circulation, and evaluating the topography.
All of that would have to be left to future missions, and the Mars Observer goes into NASA's annals as a major failure. If anything was gained from the $980 million project, the scientific instruments developed for Observer were used by subsequent orbiters.