We saw the rocket descend.
move or slope downward
come from a higher or prior level in a hierarchy — as a person from an ancestor
come or arrive — especially from above — such as night or darkness
In addition to referencing a change in physical position, descend is often used metaphorically. For example, to "descend into poverty" is to move to a lower or less good condition.
Similarly, descend can reference moving down a hierarchy or developing from something in the past — as in "She descended from royalty". To "descend from a discussion of mammals to a discussion of rodents" is to move down the hierarchy of animal classifications.
More rarely, descend can mean "to arrive" — especially when many arrive suddenly — as in "Thieves descended upon us."