The Peeps are maintained at a constant temperature of  -10 Degrees Celsius.  As there core temperature drops they are seemingly unaffected.  After 20 minutes, the Peeps are checked and it is found that something catastrophic has happened to the blue chick/duck peep.  At this point  all blue chick/duck peeps are scrubbed from the project until a full examination of the remains can be made.
 

Upon entering an alien atmosphere, Peeps can expect temperatures to increase by 600 degrees within seconds.  This condition can be simulated by placing the frozen peeps into a modified infra-red french fry warmer and boosting the power to 400 volts for a blinding 5 second blast.

When the smoke clears, the Peeps show signs of burning and superficial melting.  It seems that they have lost some of their shape memory.  Any other snack food or mammal would liquefy under these conditions but Peeps seem to be well suited to radical temperature variations.