The International Space Station, once a place where astronauts would share food and facilities, is said to be embroiled in a Cold War-like stand-off.
A Russian cosmonaut has complained he is no longer allowed to use a US toilet as well as a US exercise bike.
Gennady Padalka, 50, told Russia's Novaya Gazeta newspaper the lack of sharing was lowering the crew's morale.
Worse still, the regulations now required US and Russian cosmonauts to eat their own rations, he added.
"They also recommend us to only use national toilets," the newspaper quoted him as saying.
Among the new crew was US billionaire Charles Simonyi, 60, a software tycoon who paid $35m (£24m) for his 13-day trip, during which he will help with research projects and take part in live broadcasts with schools.
if i had to pay $35m , i'd expect my own bathroom .
paying $49.95 at KNIGHT'S INN i demand my own bathroom !