After formally announcing Lance Bass' candidacy for a fall rocket mission last week, Russian officials have now signed on the dotted line with the pop star's legal representatives to send him into space.

Negotiations took place over nine days in Los Angeles and finished Monday night, according to a source close to the deal. A 400-page flight agreement finalized the terms and conditions for the 'NSYNC member to launch as a civilian cosmonaut, as agreed upon by representatives for Bass, the Russian Space Agency, the Star City cosmonaut training complex, the Russian aerospace company Energia, space commercialization company MirCorp, television company Destiny Productions and the William Morris Agency. The financial terms weren't released, but the source said the cost of sending Bass into space is close to previously reported estimates of $20 million.

Bass announced his wish to go into orbit five months ago, calling it a "lifelong dream" (see ). Since then, the Russians had hedged on confirming that discussions were taking place, until last week when the Russian Space Agency sent a letter to its partners in the International Space Station asking them to consider Bass as their candidate (see ).

"We recognize that his training will be shorter than desired, and we will closely monitor his progress to assure his flight will be conducted safely and that he is fully ready for launch in October," the letter read. "We also recognize that Mr. Bass will have a challenge to achieve the desired level of Russian language skill. But both of the Soyuz professional crew members for this flight have excellent English-language skills. ... Finally, the flight activities planned for Mr. Bass will be tailored to accommodate the shorter than usual training template."

Those same issues were brought up at a meeting of the Multilateral Crew Operations Panel last week in Quebec. Russia's space station partners — including NASA, the European Space Agency and the Canadian Space Agency — raised concerns about Bass' flight worthiness, asking for a review of his medical background, education, experience, Russian fluency and his plans for activities while in orbit.

"It boils down to this: we need more information," NASA spokesperson Dwayne Brown said. "We're continuing to assess his candidacy. But it was determined that more information is required. For instance, he needs to speak Russian. He doesn't have to be an expert, but he needs to know enough for a contingency. So we need to know, what level of fluency are we looking for?"

The MCOP also asked a higher-level group of space station partners, the Multilateral Coordination Board, to work out a plan to "mitigate the risk of disruption" of the space station and Bass' proposed crew, Brown said.

Bass' backers said the questions and concerns raised are to be expected. "This is all very normal," Destiny Productions' David Krieff said. "This is not out of the ordinary that they would need [more information]. The good news is that we've gotten to this point, where people didn't think we would get to. And now that we're here, I really can see how farfetched the whole thing must have seemed at first. But what's pushed it over the edge is how dedicated Lance is. He's unbelievable."