Korabl-Sputnik 3

This mission started off well. The Vostok spacecraft containing the dogs Pcholka and Mushka was carried successfully to orbit by the Vostok 8K72 rocket and orbited for a day. After this, a deorbit burn was performed, but the engines did not shut off as planned but burned to depletion. This would have resulted in a trajectory which would land them outside Soviet territory and the craft could have been inspected by foreign nations. Because of this, they decided to self-destruct the vehicle with an explosive charge, which immediately killed both of the dogs in the disintegration.