Imagine, if not a maggot, then an alien ribcage with flesh made of unearthly Cumberland sausages. The ribcage consists of steel hoops, the sausages are inflated bolsters of the same translucent foil that Grimshaw deploys on the intersecting botanical domes of the Eden Project, but here dotted with tiny metal discs to reflect the sun. From the outside, this is good: it shimmers gratifyingly, it might well have landed from another planet. From the inside, it works a treat in keeping the heat down - I was there on a hot sunny day, trying out the vertiginous platforms that let you see the rockets as if from a launch gantry. This clever reflective, tough insulating skin is immune to catapults, even bullets. Trouble is, this is also meant to be an observation tower to look out of. And you can hardly see anything of the outside world. For a start, it faces away from the sun, which also means away from the city centre, though its broadly triangular plan means it looks back over its shoulder a bit. But the main problem is the lack of transparency. Glass may have its problems, but at least you can see through it clearly. Here, the best you get is a dim impression of the city outside, seen as if through a thick fog.

True, it's not as if there is much to see. The centre of Leicester, a couple of miles distant, is a fine and enjoyable place once you've negotiated the ghastly inner ring roads, but out here in the suburbs the cityscape is somewhat woebegone - with the exception of the splendid Victorian Abbey Mills pumping station alongside. This now functions as Leicester's science museum on an endearingly amateurish basis. The arrival of the Space Centre - built on the site of obsolete sewage and storm water tanks - has given the place one hell of a new identity. And it has the advantage of standing among trees and meadows on the River Soar. You can walk out there from the centre along the river towpath, and it's positively sylvan most of the way.

So there you have it: a scientific building, constructed as a kind of scientific experiment. In its way, it is a research tool. But unlike the much bigger and topographically more exciting Eden Project, the National Space Centre is a one-trick pony. The tower has to do a lot of work if it is to attract all the visitors it needs to. True, it looks like no other building in the world. But will that be enough?