Take Laika, for example. In November 1957 the whole world watched in astonishment as the Soviets not only launched Sputnik 2, but revealed they had a stray mongrel in the satellite as well, making them the first to get a living organism in orbit. Everything about Laika's journey seemed to go swimmingly, until we realized the Soviets never had a safe return plan for their pooch, and they planned for her to die in space all along. Which sucks, of course, but at least she died peacefully when she ate her poisoned food dose a week into orbit, as the Soviets reported.
They honored her sacrifice with a stamp, that she might torment postal workers for generations to come.
Except, oh wait, that's not how Laika died at all. In 2002 it was revealed that Laika wasn't euthanized, but that she died in the most horrifying way possible within hours of the launch. Sputnik 2, it turned out, was something of a rush job. The whole thing had been planned and put together in four weeks, so no one should have been surprised when the thermal insulation system broke right away. Poor Laika, whose little doggy heart was already beating at four times its resting rate, found herself in a cabin that was 104 degrees Fahrenheit. Her body shut down from stress and heat within five to seven hours of her launch.