Space is a dangerous place, anything can happen in space, and astronauts are always in risk of an accident, whether in space, international space station, moon or mars missions

If a astronaut dies in space then what happens,

Actually nasa has different protocols for every mission

In low orbit missions, after death , dead body is sent in few hours

This dead body is sent through a capsule to earth

But mainly the focus is that , every crew member survive in the mission, this is priority

While on mission, on mars , the body is returned after the completion of the mission

According to nasa , 20 people had died in last 60 years in mission

Since human space exploration began just over 60 years ago, 20 people have died 14 in the NASA space shuttle tragedies of 1986 and 2003, three cosmonauts during the 1971 Soyuz 11 mission, and three astronauts in the Apollo 1 launch pad fire in 1967