NASA Administrator Mike Griffin said the U.S. space agency would begin a formal assessment in 2007 of potential approaches for sending humans to Mars, but that he did not foresee astronauts embarking on a journey to the red planet for another 20 years or longer.

“I don’t want to leave my term of office without having done at least a preliminary Mars architecture,” Griffin said, noting that the preliminary planning effort would begin next year. Actually sending astronauts to Mars, under NASA’s current plans, would not happen until after the agency leads the way back to the Moon, an objective NASA hopes to accomplish by no later than 2020. Because of that, Griffin said, he would not expect the first human Mars expedition to begin until at least “the late 2020s.”

Speaking to the ninth international convention of the Mars Society here, Griffin said he understood the timetable was too slow for many in attendance at the gathering, but encouraged the group to support NASA’s stepwise approach that entails finishing the international space station and going to the Moon before setting out for Mars.

“I know that some of you are frustrated by how arduous the journey has been even to this point and by the many challenges we still face before we embark on mankind’s first voyage to Mars,” Griffin said. “As someone who has devoted his career to the space business I share these frustrations.”

Griffin went on to explain that even though the White House and Congress have endorsed a plan for NASA to lead the way out of low Earth orbit, the space agency is still expected to push the envelope in such diverse areas as aeronautics, astronomy and environmental monitoring.

“There are many disparate goals that are held by NASA’s various stakeholders and we try, very hard, to move the agency forward in a manner that promotes unity among rather than division between these stakeholders. It is not easy,” Griffin said. “If the blunt truth be told, prior to the loss of the Space Shuttle Columbia a few years ago, NASA suffered from a long period of benign neglect both by the public and our government stakeholders concerning the broader purposes of our nation’s space enterprise, and especially human spaceflight.”

Griffin also sought to assure the group that NASA’s return to the Moon does help set the stage for missions to Mars.

“We are going to be using the Moon as much as possible to help us learn how to go to Mars,” he said.

Noting that future Mars expeditions would have to do a fair amount of living off the land, Griffin said NASA still has a lot to learn about so-called in-situ resource utilization.

“In-situ resource utilization is going to be crucial to going to Mars. We need to start learning how to do that on the Moon. Yes, they are not the same environment,” Griffin said, adding that he did not buy arguments that lessons learned on the Moon would not be applicable to Mars.

“That cannot be true,” he said. “That would be like saying people who do oil rigs in deep ocean would have nothing of value to contribute to people who drill for oil on the North Slope or Siberia. There are huge differences. There are also great commonalities.”

Griffin also said that NASA chose the exploration launch vehicles that it did to help set the stage for eventual Mars missions.

“If I were just designing a lunar architecture, the most elementary common sense would have told me to make both of those vehicles the same size so I could benefit from economies of production, economies of building two of the same vehicle. I didn’t do that,” Griffin said. Why did we not do that? We didn’t do that because if I want to go to Mars and believe we need something like a million pounds to low Earth orbit to do that, then I want to do that in five or six launches not 10 or 12.”