Hubble's successor faces the chop
[Graphic: Meet the James Webb Space Telscope. Click to massificate)
Few could argue that Hubble is the ‘daddy’ of all space telescopes. In its twenty years of operation, it has pushed back the boundaries of astronomy and physics, sent back images that have captured the imagination of an entire planet and provided PC screen savers to a generation. But all good things come to an end and, although more powerful than ever, Hubble’s days are numbered but will its successor be given its chance to step into 'daddy's' shoes?
Set for launch in three years, the James Webb Space Telescope would have allowed science to peer-deeper into space and look further back in time than ever before, but now this marvelous machine's future is looking doubtful. Last year, a review panel found that the effort to build JWST was riddled with bad planning, poor cost control, and too much optimism about the technical challenges it faced. The report concluded that project was so seriously over budget and behind schedule that only a quick infusion of cash — an extra £3112 million over the next two years — would prevent the launch date from slipping to 2018.
America's lawmakers have just cut NASA's budget by £1 billion and announced that it would be terminating the James Webb Space Telescope.
Meanwhile, construction on the telescope continues, and some technical milestones have been reached. On June 30th, Nasa announced that they had finished polishing the telescope's huge beryllium mirrors.
I'm not qualified to comment on how budgets work, or how it doesn't seem to make sense to can something that has gotten so very far, but I can comment on what could have (should still) have been.
[How JSW compares to Hubble. Click to enlargenify]
Despite its problems, Webb remains a spectacular beast. Whereas Hubble looked like a telescope that found its way into space, Webb looks like a vision of scar-gazing's future. Resembling more of an interstellar sailing ship than a telescope, Webb’s colossal light-collecting mirrors sit atop a Sun-shield the size of a tennis court and, once unfolded to their full 6.5m spread, the array of hexagonal mirrors will dwarf Hubble’s single 2.4m mirror.
James Webb Space Telescope beryllium mirror segments undergoing cryogenic tests
Webb would have had access to none of the home comforts that Hubble has been enjoying in its Earth-hugging 570km-high orbit. Positioned some 1.5million km from Earth, not only will Webb be well beyond the sort of help saw Hubble, first fixed of a faulty mirror, then repeatedly upgraded, repaired and serviced, but, should anything go wrong craft, it will be well beyond any sort of help at all.
Webb’s extreme location raised other problems that have to be tackled by Nasa with some pretty extreme engineering solutions. At this distance from Earth, temperatures are lower than those at Pluto, substances that are gases on Earth are liquids and rubber behaves like glass. So Nasa had to dig around the kit bag of science fiction to find a solution. The craft’s chassis – the metal frame to which all its components and experiments are attached – has been made of a material you might recognise from James Cameron’s blue-tinted fantasy, Avatar: ‘Unobtainium’.
‘Unobtainium’ is actually the name given to a material needed to fulfil a design that is too rare, too costly, or too impossible to build. The Nasa team needed a material that could withstand the super-cold temperatures (as low as -246°C) without expanding or contracting so much as fraction of a millimetre. Even such a tiny change in the chassis’ shape would throw all of the telescope’s experiments out of alignment.
How could they think of cancelling a machine that uses something as cool as 'unobtainium'? Crazy... just crazy