Space Shuttle Atlantis’ return to Earth July 21 following a 13-day mission to deliver supplies to the international space station brings to an end three decades of relative stability in the U.S. human spaceflight program. With Atlantis and her two sister orbiters now bound for museums across the country, all that seems certain is it will be five years — and conceivably longer — before the United States is once again capable of launching astronauts into orbit.

Coming as it has amid deep division and uncertainty over the future of U.S. human spaceflight, the shuttle’s retirement has fueled widespread and occasionally hyperbolic outcry about the end of U.S. leadership in space exploration, even the end of the entire space program. Many find it highly distasteful, not to mention ironic, that NASA will be entirely reliant on Russia — which lost to the United States in the Cold War race to the Moon — to transport astronauts to and from the space station for the next several years.

It’s also noteworthy that the space shuttle completed its 135th and final mission just one day after the 42nd anniversary of the first astronaut landing on the Moon, which strangely seems more distant today than it might have in 1961 when then-President John F. Kennedy declared the nation’s intent to reach that destination before the decade was out. President Kennedy meant it, and his leadership and commitment endured long after his assassination.

Today the United States seems chronically incapable of setting a long-term objective in human space exploration and sticking to it. There are myriad reasons for this, but among them was the longevity and stability of the space shuttle which, once ensconced as the centerpiece of the U.S. civil space program, proved nearly impossible to dislodge despite it obvious limitations. Finite budgets made it impossible to continue flying the shuttle while striking out for destinations beyond low Earth orbit and when push came to shove, shuttle invariably won out.

It was a technical marvel, perhaps more complex than any machine built before or even since. But that was a liability; extreme complexity is not conducive to the routine operations originally envisioned for the orbiter. The shuttle never flew more than nine missions in a single calendar year, a far cry from the dozens per year that would have made it relatively economical to operate on a per-launch basis. The aftermath of the 1986 Challenger disaster formally capped the shuttle’s utility and flight rate via national policy; the White House decreed that the orbiter, previously the launcher of preference for all U.S. payloads, was reserved strictly for missions requiring direct, hands-on human involvement.

Shuttle’s other glaring weakness was its inability to deliver astronauts to destinations beyond low Earth orbit. The international space station, NASA’s most ambitious undertaking since Apollo, was a product of that limitation. And because its non-Russian components were designed to launch on the shuttle, the space station served as another compelling raison d’être for the orbiter fleet for some two decades ending with Atlantis’ historic final flight.

As is becoming more painfully evident by the day, the shuttle also was an important economic engine; the post-production program provided nearly 19,000 jobs — many of them highly skilled and well paying — in several states including Florida, Texas and California. With that came political clout; from an economic standpoint the shuttle, conceived as a means to an end, became an end in and of itself.

It took a second tragedy, the 2003 destruction of Space Shuttle Columbia, to force a re-evaluation of the U.S. human spaceflight program, which led to the decision by then-President George W. Bush to retire the orbiter fleet and chart a return course to the Moon in preparation for a future journey to Mars. NASA, having been handed a presidential mandate, crafted an implementation architecture dubbed Constellation that leveraged its investments in space shuttle technology and infrastructure.

Constellation was a technically and programmatically coherent, step-by-step blueprint whose component pieces built upon one another. Ever mindful that undertakings of this scale require long-term support, Constellation’s architects built in political robustness as well: Congress endorsed shuttle’s retirement in part because Constellation promised to absorb much of the work force that otherwise would be displaced.

That was the grand bargain that U.S. President Barack Obama unilaterally abrogated in opting to dismantle Constellation and bet the nation’s human spaceflight future on the NASA-aided emergence of commercial astronaut taxi services and new technologies that would change the economics of deep space exploration. Constellation was under-funded from the start and White House doubts about the program’s long-term affordability were not unfounded. But the program was never in disarray, as at least one administration official has asserted — properly funded it had a reasonable chance of succeeding, if not on the schedule originally envisioned by the Bush administration.

Whatever Constellation’s flaws, President Obama clearly didn’t think through the implications of its cancellation, particularly for the U.S. space and strategic industrial base. The White House also badly misjudged the level of resistance its proposal would encounter on Capitol Hill. But some of the criticisms now being leveled at the administration, among them that it has willfully ceded U.S. leadership in space and left the nation with no means to launch astronauts, are misplaced. In signing off on Constellation, for example, Congress accepted that there would be a multiyear gap in U.S. human spaceflight capability following shuttle’s retirement.

Lawmakers had an obvious political motive — job preservation — in directing NASA, against White House wishes, to build a deep space capsule and heavy-lift rocket, both of which were key components of the Constellation architecture. But there also was genuine concern that the United States was betting replacement of a treasured national capability on a roll of the dice, with no realistic plan for reaching destinations beyond low Earth orbit.

The result, unfortunately, is a bifurcated program that lacks many of the key ingredients for success: architectural coherence; unified political and industry support; adequate funding; and concrete long-term objectives. The most appropriate tribute the White House and Congress can pay to the shuttle’s legacy — and those who risked and lost their lives in the name of space exploration — is to stop talking past one another and get cracking together on a coherent and affordable strategy that returns the expansion of humankind’s frontier to its rightful place at the forefront of U.S. manned spaceflight objectives.