HOUSTON --After Thursday's Discovery shuttle launch, there are just two more shuttle flights left before the shuttle retires. The final flight could launch in June, but right now there's no money to pay for it. We caught up with the commander of the shuttle's final mission on Wednesday, and he's in the midst of training for a flight that may not get off the ground. This is one of those only-in-Washington deals. This mission we're talking about is approved. Congress passed a law saying it should fly, but Congress hasn't approved the money. NASA keeps moving the deadline to decide, but even as we pass those, crews keep training. Chris Ferguson is training every day to get back to space. "Could you think of a better job in the world?" Ferguson said. He's been twice before and is now slated to command the shuttle's final flight ever. Ferguson is training for a launch as soon as June. His pilot, Doug Hurly, is, too. "It's sad to see it go," Hurly said. But neither of them knows if there will be money to pay for the mission. "That is the million-dollar question," Hurly said. It's actually a $450 million question. That's what a launch costs. The problem is that Congress hasn't passed a new budget for next year, leaving NASA without a clear spending plan. The space agency is optimistic Congress will help and says the mission will fly. "The actual math I don't understand, but effectively we've gotten the letter from headquarters saying that we will fly STS 135 regardless of what happens with the NASA budget ," Shuttle Program Manager Mike Moses said. But caveats, like a $600 million budget cut could force NASA to reconsider. And that is exactly what the House of Representatives did last Saturday. They slashed $61 billion in federal spending, including $600 million from NASA. If that cut makes it through the Senate, NASA's final flight may never leave the launch pad. "It's still a fight," U.S. Rep. Pete Olson said. Olson voted for the overall cuts, but says NASA needs to shuffle money around within the agency and find the cash to send the final manned mission to space, taking money from things like climate science to do it. "There are 15 other agencies in the government doing that research. NASA shouldn't do that. NASA should focus on what I believe is their primary mission -- human space exploration," Olson said. The astronauts on board want to fly and they're getting ready, hoping Congress won't stand in the way. "We're optimistic it's going to be there when we get there. If it is, fantastic and if it's not, well it's the will of taxpayers," Ferguson said. The flight is a resupply mission for the International Space Station. The shuttle would deliver a year of supplies and spare parts to help extend the life of the station until 2020. Some of those things are apparently too big to be carried on any vehicle other than the shuttle. NASA tells us without the flight, the crew size of the space station might have to be reduced.