Russian cosmonauts receive up to $150,000 for a mission on board the International Space Station (ISS), a senior space official said Thursday.

"For six months of work on the ISS, a Russian cosmonaut gets an equivalent of $130,000-150,000 in Russian currency," Vladimir Solovyev said, head of the Russian segment of the ISS.

Solovyev admitted that the cosmonauts' work in orbit is difficult, in both professional and health terms. It involves maintaining the station and conducting scientific experiments and observations.

The tasks are performed in weightless conditions, while the body loses bone and muscle mass. To counter these losses, astronauts have to maintain a strenuous exercise schedule.

Russian cosmonauts sign specific contracts for each mission, and their pay differs significantly from what they receive as a regular salary while on Earth, Solovyev said.

Contrary to Russians, NASA astronauts get an average annual salary of up to $130,000 regardless if they are on Earth or in space.