It was equipped to take images of the lunar surface with a television-like system, estimate the Moon's mass and topography of the poles, record the distribution and velocity of micrometeorites, and study radiation, magnetic fields, and low frequency electromagnetic waves in space.

The launch was uneventful until T+66 seconds when a severe axial disturbance was recorded, followed by rapid loss of LOX tank pressure and changes in the Atlas's engine exhaust indicative of oxidizer starvation.

The immediate cause of the failure was unclear, but thought to be related to either the adapter mating the Able stages to the Atlas coming loose and being rammed into the LOX tank or else aerodynamic buffeting on the launch vehicle.

The recovered Able second stage showed no sign that engine ignition or operation had taken place, and the most probable cause of the failure was believed to be aerodynamic flexing of the Able adapter which then ruptured the Atlas's LOX tank.

The crippled booster continued to fly for a few seconds afterwards, but the structural collapse of the Atlas's forward section combined with the loss of LOX pressure to the propellant feed system resulted in engine shutdown and vehicle self-destruction.

As a result of this failure and Mercury-Atlas 1 five months earlier due to a similar episode of aerodynamic bending in the forward portion of the LOX tank, GD/A began requiring that all Atlas upper stage/payload combinations undergo proper structural dynamics testing.

A plasma probe was mounted on the sphere to measure energy and momentum distribution of protons above a few kilovolts to study the radiation effect of solar flares.