As we approach the last flight of the space shuttle, many have suggested that we are witnessing the end of U.S. human spaceflight. That is certainly not the case: Now that the International Space Station, the shuttle's single most valuable contribution to research, is finally ready, the next decade of U.S. human spaceflight activity will be focused on utilizing this unique space laboratory. It is when we look farther into the future, to 2020 and beyond, that we face the possibility there will be no U.S. program of human space exploration, and thus that the U.S. government human spaceflight program will come to an end after work on the space station phases out.
For the past forty years, the space shuttle has been the centerpiece of the U.S. space program. In recent years, it has been used almost exclusively to launch the various elements of the International Space Station (ISS) and to assemble them in Earth orbit through numerous astronaut spacewalks. (It was that task, in fact, that was among the primary drivers of the shuttle's design in the 1970-1971 period.) For the next decade, rotating six-person crew from the fifteen ISS partner nations will operate the facility and carry out a wide variety of scientific and engineering experiments. It is certainly embarrassing that for the time being U.S. astronauts will be traveling to and from the ISS in Russian space taxis. But there will be Americans working in space for at least ten years to come.
The Columbia Accident Investigation Board in its 2003 report called the fact that there was no replacement for the space shuttle in sight a "failure of national leadership." Eight years later, there is still no replacement, although current plans call for an industry-NASA partnership to develop, by mid-decade, one or more small spacecraft and their associated launch vehicle to carry crews to the ISS. One can only hope that the nation's leaders will support this effort, and that it will be successful, sooner rather than later. It will be hard for the United States to sustain its position as the world's leading space country if there is an extended period during which it has to depend on others for human access to space.
Then what? The tougher question is whether the United States will commit to traveling beyond Earth orbit; no human has done so since the final Apollo mission, Apollo 17, in December 1972. In 2004, President George W. Bush laid out what remains a worthy goal: to "implement a sustained and affordable human and robotic program to explore the solar system and beyond." The first step was to have been a return to the Moon by 2020, but the program to develop the capabilities to achieve that goal, called Constellation, was deemed in 2009 by an expert panel "unexecutable." Last year the Obama administration cancelled the program, thereby abandoning the "Moon by 2020" goal, but the president called for a continuing commitment to space exploration, saying, "If we fail to press forward in the pursuit of discovery, we are ceding our future and we are ceding that essential element of the American character."
