Fifty years ago, the Discoverer III probe was launched by a Thor Agena A rocket from Vandenburg, CA. As part of the scientific payload, a number of mice rode the rocket into out space. Unfortunately, the probe failed to reach orbit as the orbital thrusters fired incorrectly and sent the payload toward the Earth. The probe, along with its passenger complement of rodents, burned up in the atmosphere.
Personal Flashback: As part of a science lesson I was teaching my class of fifth graders, we built a Quest model rocket with a payload section. The Code of Model Rocketry forbids the use of mammals of any type in model rocket experiments, and my students had me purchase a number of crickets from the pet store that we kept and "trained" as insect-o-nauts. Saved from certain death as a dinner for someone's pet, one of our brave crickets was placed into the rocket's payload section (of course with a clear see-through section) and the rocket prepped for launch from the back field of the school. Alas, the construction of the payload section was evidently not as well completed as the booster section. The rocket soared upward beautifully, but at apogee, the ejection charge of the rocket motor caused the payload and nose cone to detach from the rocket. And I do mean detach. With an audible BANG every piece came apart, the chute detached from the payload section and every piece of the section detached from every other piece. Evidently that included the cricket. The explorer's remains were never recovered.