For the last five years or so, NASA has sold the public on a Journey to Mars, a grand voyage by which the agency will land humans on the red planet during the 2030s. With just budgetary increases for inflation, the agency said, it had the resources for humanity's next great step, to land crews safely on Mars, and to bring them home. The agency's new rocket, the Space Launch System, and spacecraft, Orion, were sold by NASA administrator Charles Bolden as the vehicles that would get the job done.
There were plenty of naysayers. For example, a National Research Council report cautioned that the agency had too much work, and too little funds, to accomplish these goals in the 2030s with the SLS rocket—and that sustaining a "Mars program" into the 2040s would be a tremendous challenge. NASA's remarkable response to this critical report was that it validated the Journey to Mars.
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 (see video).
"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. The reality is that the SLS rocket and Orion spacecraft have cost a lot to build, and therefore NASA hasn't been able to begin designing vehicles to land on Mars or ascend from the surface.
Agency officials have also been loath to mention the possibility of NASA astronauts landing on the Moon, because George W. Bush had an initiative to return to the Moon that President Obama canceled. However, Gerstenmaier opened the door to this possibility Wednesday.