Curry also refuted the contention that Voss and Helms were told to keep their distance from Tito. Usachev and his American colleagues, however, were told to take special precautions because neither Tito nor his cosmonaut colleagues had been fully trained on the operation of critical systems within the U.S. segment of the station.

"We wanted to make sure we gave them lots of time for safety briefings, [and] that they were always available to escort Mr. Tito and the other two cosmonauts as required into the U.S. segment to make sure they knew where the dangers lie," he said.

"Over and above that, I don’t think there was any special guidance given to them."

"I think the major problems were caused by the lack of coordination on the ground and the difficulties between the Russian space agency and the rest of the partners," Voss said.

"As far as the crew was concerned, we did okay up here, got along fine, and it was a reasonable week for us. We got a little bit of rest, which was pleasant."

That’s not to say, however, that Voss thinks tourist trips to the station should become commonplace without what he and other NASA officials consider requisite training.

"This is not just a normal place that a tourist would go. There are a lot of hazardous things going on around here," the veteran astronaut said.

"If you moved a certain valve the wrong way, you could cause some very serious damage, maybe even death onboard. So it’s serious business being up here, and it requires training," he added.

"But any normal human who's healthy and who goes through the required training one day, I think, will be able to come up to the International Space Station."