The original substance can be recovered. is this and physical change or chemical change?

That's not true. It would in fact be physical.

Explanation:

physical change: some of its physical properties may change but its identity does not

space exploration has led to the development and technological improvement of many everyday items. (if this answer is wrong i will find the right answer) : )

chemical digestion occurs in the stomach were hcl and pepsin forms chyme, the mouth in which salivary amylase breaks down starch to form bolus, and the small intestine specifically the duodenum.