The United States should not try to keep its space shuttles flying beyond 2010.
Perhaps the most memorable achievement of the US space shuttle fleet was Endeavour's first servicing mission to the Hubble Space Telescope in December 1993. Here was something that only humans in space could achieve — the gentle snagging of the satellite with the shuttle's arm; the five spacewalks to install corrective optics, new instruments, gyrosocopes and solar panels; and finally, the release of a clear-eyed telescope capable of discerning finer details, deeper in the cosmos, than any other telescope in history.
On 11 May (see page 21), the space shuttle Atlantis is scheduled to make what is not just the last trip to the Hubble, but also the last space-shuttle trip to any destination other than the still-rather-pointless International Space Station, which is due seven more visits before shuttle flight operations cease in September 2010. As such, the Hubble flight marks — or should mark — the end of an era. Unfortunately, Congress has started making moves to keep the shuttle flying into 2011. The administration of President Barack Obama should resist this idea — and at the same time, take the opportunity to state more clearly its objectives for NASA and human spaceflight.
The “vision for space exploration” articulated by former US president George W. Bush in 2004 called for the shuttle to be replaced by an all-new system, now called Constellation, in which human crews would ride into space inside a bell-shaped Orion capsule mounted atop an Ares rocket. Constellation is in some ways a reconceived version of the Apollo infrastructure, and as such can seem technologically retrograde. But unlike the shuttle, it opens up the possibility of missions beyond low-Earth orbit — missions to the Moon, nearby asteroids and perhaps Mars.
If a nation must have human spaceflight — and it seems that, in terms of practical politics, the United States must — then travel to such interesting places seems the best of the available goals. That makes Constellation the way forwards. There is, however, a significant gap between the last shuttle flight next year and the first launch of an Orion capsule to the space station, which might not take place until 2015. Such a gap was planned; indeed, it was one of the space vision's braver aspects, recognizing that creating a new system while running the old one was not a viable option. Yet delays in Constellation's development mean that the gap is getting longer, leaving the United States dependent on Russia to deliver people to the space station in the interval. That perceived ignominy, combined with the job upheaval threatened by the demise of the shuttle, seems to some in Congress a reason to stretch out the shuttle's old age.
It is not. The basic logic remains sound: closing one human spaceflight operation before the next is functional saves money and ensures focus. NASA's next administrator, whenever he or she is finally named and confirmed, should be free to concentrate on meeting the goals that Constellation was designed for — without the distraction of also having to drag out the shuttle programme.
That administrator should also make it clear that human spaceflight, although a huge part of NASA's legacy, is not the overarching justification for the agency's existence. NASA also has a great deal of urgent work to do in studying Earth from orbit — and in providing new visions of the Universe beyond Earth. Servicing the Hubble might have been the best thing the shuttles did. But the images and knowledge provided by the Hubble, more than the mostly routine missions of the shuttle, are closer to the essence of what the space programme is there for.