For years, NASA has been chalking out and expanding its plans to go to Mars. The agency's Journey to Mars project aims to land humans on the red planet during the 2030s. For years, the agency has been reassuring us that it will be able to make do all those audacious projects within the budget it gets. Until now, that is. From a report: Now, finally, the agency appears to have bended toward reality. During a propulsion meeting of the American Institute for Aeronautics and Astronautics on Wednesday, NASA's chief of human spaceflight acknowledged that the agency doesn't really have the funding it needs to reach Mars with the SLS rocket and Orion spacecraft. These vehicles have cost too much to build, and too much to fly, and therefore NASA hasn't been able to begin designing vehicles to land on Mars or ascend from the surface. "I can't put a date on humans on Mars, and the reason really is the other piece is, at the budget levels we described, this roughly 2 percent increase, we don't have the surface systems available for Mars," said NASA's William H. Gerstenmaier, responding to a question about when NASA will send humans to the surface of Mars. "And that entry, descent and landing is a huge challenge for us for Mars." This seems like a fairly common sense statement, but it's something that NASA officials have largely glossed over -- at least in public -- during the agency's promotion of a Journey to Mars.