WASHINGTON (Reuters) - NASA's relations with Russia are still recovering from a ``symmetry of mistrust'' that festered over California businessman Dennis Tito's flight to the International Space Station, U.S. space agency chief Daniel Goldin said in a Reuters interview.

``It did get to a very low point,'' Goldin said, speaking in his ninth-floor office at the National Aeronautics and Space Administration headquarters. ``The turning point came when there was a symmetry of mistrust.''

Describing relations between the two agencies nearly a month after Tito's voyage, Goldin said last week they were ''better but not perfect, and at times stressful ... We're not back to where we were, but I think we're over the worst of it.''

NASA and other partners in the International Space Station had strenuously objected when the Russians said they would send Tito aboard a Soyuz taxi flight to the station. Tito reportedly paid $20 million to the cash-strapped Russian agency.

As Tito's April launch date approached, the distrust was thick on both sides, Goldin said, especially when computer problems developed aboard the station while space shuttle Endeavour was docked there. Endeavour's systems were used as a backup, but the shuttle had to leave the station before the Soyuz craft could arrive.

Some Russians doubted the shuttle's computer problem was genuine and some Americans and other international partners in the station questioned whether the Russians needed to launch Soyuz at that time, Goldin said.

STRESSFUL, BUT NOT DYSFUNCTIONAL

``The stress built up to mistrust, which is unacceptable in the space program,'' he said. ``It wasn't yet dysfunctional, but it was a very bad sign.''

The immediate problem was solved between Goldin and his Russian counterpart Yuri Koptev after Goldin placed a middle-of-the-night phone call, catching Koptev just as he was leaving for the Soyuz launch site in Kazakhstan.

``He was very sensitive to the issues and he didn't want to have a problem either,'' Goldin said of Koptev, who suggested pushing back the Soyuz launch by a day or two to give NASA time to fix Endeavour's computer glitch. ``It was an elegant idea and it was brilliant,'' Goldin said.

Goldin has been around the aerospace community long enough to have some perspective. He is the longest-serving chief of NASA, having been nominated by President George Bush, the current president's father, in 1992.

Before that he worked at the aerospace and defense firm TRW Inc. Since the collapse of the Soviet Union and the forging of a space alliance with Russia, Goldin has had the singular experience of hugging people whose Soviet cities were targeted by missiles his company worked on.

``Yuri and I were on different sides of the Cold War and many of the people we work with were on different sides of the Cold War,'' Goldin said. ``Yes, I'm not embarrassed that we hug each other.''

The cowboy-booted Goldin -- extra-wide feet make boots his favored footwear -- said he took responsibility for canceling

NASA's civilian-in-space programs six years after the 1986 shuttle Challenger disaster, which killed six astronauts and the first teacher in space, Christa McAuliffe.

He said he feels personally responsible for the safety of every shuttle astronaut, and keeps a large high-definition video screen in his office for preflight video interviews with each one.

``I want to peer right into their souls and I want to see that this team meshes,'' Goldin said.

CREW CHEMISTRY, SPACE CHORES

This notion of crew chemistry was one cause for concern over the Tito flight, even though it was NASA that barred Tito from training with his Russian colleagues when they went to Johnson Space Center in Houston in March.

``The space tourist that went up, I don't have anything against him, in fact I'm jealous to a degree ... but safety comes first and we felt the rules were violated.''

The crisis over Tito occurred at least in part because his original contract had him flying aboard the Soyuz to the old Soviet-made Mir station. When Mir deteriorated and then had to ditch in the South Pacific in March, the Russians switched his destination to the international station.

Tito spent his flight taking pictures, doing some tasks, enjoying the view and listening to opera, an agenda that goes counter to Goldin's vision for nonprofessional space travelers.

Within three or four years, Goldin said, nonprofessionals

will probably travel to the space station after going through an established training and screening program, but they will not be tourists.

``We'd like to train people to do mundane tasks, to offload the astronauts,'' Goldin said. ``You know, do windows and floors -- that's a little expression ... so then the astronauts could be available to do higher-level work.''

SHORTEST DISTANCE TO MARS

The $95 billion station, often the target of congressional budget cutters and U.S. public scorn, is the most direct route to human exploration of Mars, Goldin said. Humans could go to Earth's planetary neighbor in 10 years at the least, and no more than 20 years, he said.

The space station is critical to solving biomedical problems associated with long-duration space flight, and while the station is being built, others at NASA and at other space agencies can work on finding the best landing sites on the Red Planet, determining whether there is the potential for water, fuel or even life there, Goldin said.

He predicted humans would visit Mars within 20 years. ``Mark my words: we're on Mars before the end of the second decade of this century.''

Will Goldin still be at NASA to see it?

``I don't know. I don't make those decisions,'' Goldin said, but added that he had told the current Bush administration he would help with a transition if his replacement is chosen.

Asked whether there was any indication that this was happening, Goldin said, ``I don't discuss those things.''