Columbia

Six years ago today, the first space shuttle, after suffering damage to its protective heat tiles, disintegrated durimg re-entry. All aboard were lost.

That tragedy became a pivot for the American manned spaceflight program. Before it, NASA was flying the shuttles and constructing the ISS, but there was nothing beyond. The Bush administration used the period after the loss of Columbia to develop a plan for the next few decades. That plan called for the retirement of the shuttle fleet after the construction of the ISS was complete, and the development of a new spaceship that would take astronaurs back to the Moon, and, eventually, on to Mars. All of that was to be done while holding NASA's budget to roughly one percent of the federal budget.

Where that plan will go under the Obama administration, amid economic difficulties, is unclear. At one point, Mr. Obama looked poised to announce his choice for NASA administrator before his inauguration, suggesting a real interest in space policy, but that didn't happen. The legacy of Columbia and her final crew has yet to be determined.