Would a cadaver decompose faster or slower in a vacuum?

Answer 1

There are two main processes of decomposition with biological organisms, those being Aerobic and Anaerobic. Aerobic occurs in the presence of the element Oxygen. The Latin prefix "An" means "not", so anaerobic occurs when there is no oxygen present.

Aerobic processes are generally faster, since oxygen is an accelerant, or more specifically, it causes decomposition to occur more rapidly than if it were not present. Oxygen is generally considered neither a fuel not a catalyst, though it can be the latter in specific instances (see: Oxygen oxygen).

Since a vacuum has a distinct lack of Oxygen, the process would become anaerobic as soon as the internal oxygen within the object (body, piece of cheese, tomato, et al) ran out.

Additionally, the vacuum adds other considerations. The item under examination would also desiccate (or dry out) as the volatiles, such as water, moved to the vacuum. Lacking both water and elemental oxygen, virtually all biological processes would cease.

It could last forever, with no significant deterioration, if the vacuum were maintained, so not only would decomposition be slower, it would completely cease.