The upper-stage rocket failed and the craft re-entered the atmosphere after reaching a sub-orbital apogee of . In the event of unscheduled return to the surface, the craft was to eject the dogs and self-destruct, but the ejection seat failed and the primary destruct mechanism shorted out. The animals were thus still in the intact capsule when it returned to the surface. The backup self-destruct mechanism was set to a 60-hour timer, so a team was quickly sent out to locate and recover the capsule.