About two dozen activists, some wearing space suits with monkey masks, staged a noisy protest Friday to demand the federal government cancel a $33 million project to send monkeys into space.

Some of the protesters chanted, “NASA, stop torturing monkeys now!”

The demonstration was an appeal to the Senate, where a vote was scheduled on an amendment that could cancel the NASA monkey project, involving the United States, France and Russia. The project studies bone loss and effects of space travel on astronauts’ muscles.

Two monkeys are scheduled to fly into space in October.

“I’m not an extremist. I could see in some cases where you can use animals for medical reasons, but I can’t justify this in my mind,” said Barbara Chase as she passed out flyers at the downtown Federal Building.

“The Russians have sent dogs up into space and they’ve done more of this animal kinds of things in space,” said Elliot Katz, a veterinarian who founded In Defense of Animals. “Their country as a rule seems less sensitive to the needs of animals than ours has been.”