The memorial service for 30-year-old Mandla Maseko, popularly known as Spaceboy, is being held at Airforce Base in Swartkop in Pretoria.
Maseko died in a motorbike accident at the weekend. He became popular after he was set to become the first black African in space.
Maseko earned the name Spaceboy after he beat 1 million people to become one of the 23 people, who won a seat sponsored by the Axe Apollo Space Academy, on an hour-long suborbital trip in 2014.
Spaceboy will be buried on Saturday at Zandfontein cemetery in Pretoria.