NASA plans to complete the International Space Station by 2010. Credit: © NASA

This week NASA submitted proposals to the other space agencies involved in the International Space Station: it called for an expansion of the station's crew from three to as many as six astronauts to fully exploit the facilities in the Destiny science module. Destiny, a $1.4-billion laboratory for scientific research, was delivered to the ISS by the Atlantis space shuttle in February 2001.

But what is the extra science that NASA aims to do? The answer is, presumably, more of the same: more growing crystals, more measuring fluid viscosity and watching materials burn, more studies on humans and plants in zero gravity. More experiments whose scientific impact has so far been almost non-existent.

Am I just being impatient? Expecting an instant payoff from this science is, in the words of one ISS senior scientist recently, "a little like expecting a pinch hitter to hit a home run every time he comes up to the plate". By which I guess he means that it is expecting a little too much. Sure, the ISS has been up there for 20 years and has cost in excess of US$60 billion; but just give it a little more time (and money).

I know that the ISS, crippled by NASA's grounding of the space shuttles after the Columbia disaster last year, manned by a skeleton crew, still incomplete after two decades, denounced by several major US scientific organizations, is an easy target. I realize that. So let's start shooting.

There was never a good scientific case for the ISS

I know the ISS is an easy target. I realise that. So let's start shooting.

Why was the ISS project ever begun? That depends on whom you ask, and when. "Its mission has never been very clear," says Bob Park of the American Physical Society. "Each administration cooks up a new explanation for it." Park is right: there were never any well-defined scientific goals for this orbiting folly, just a vague promise that, once it was up there, something fantastic would come of it.

"You approach research in space in a similar way that you do on Earth," says one former astronaut. By this, he doesn't seem to mean that you build a massively expensive lab in the remotest location you can find and then hope someone thinks of something to do with it. He means that: "Some results are fairly dramatic and come early. For others, it takes a long time." So isn't it about time we got the "dramatic early" results from the ISS?

Of course, one reason for sending people into space is to find out what happens when you send people into space. Then you can decide if it is a good idea to send people into space. The trouble is, the Columbia shuttle already gave us one answer to that question on 1 February 2003.

The ISS keeps outrunning its budget

Ronald Reagan told the United States in 1984 that the space station would take six years to build and would cost $8 billion. Sixteen years and tens of billions of dollars later, NASA enlisted the help of 15 other nations and promised that the station would be complete by 2005. The latest NASA plans say it will be finished by the end of this decade, assuming that the shuttles are running again within a year. (NASA had better be right, because in 2010 the shuttles will be decommissioned.)

Scientific results from the ISS have been extremely limited

One reason for sending people into space is to find out what happens when you send people into space. Then you can decide if it is a good idea to send people into space

So what do we have to show for all this effort and expense? Well, we know that crystals grown in space are different. As Park says: "They cost more. Three orders of magnitude more." But wasn't microgravity going to give us purer protein crystals, leading to new drugs and treatments for cancer? Not likely. In 2000 a US National Research Council study concluded that the impact of space-grown crystals on molecular biology had been "extremely limited".

In 1998, the American Society for Cell Biology stated that "no serious contributions to knowledge of protein structure or to drug discovery or design have yet been made in space. Thus, there is no justification for a NASA protein-crystallization programme." Yet five years later, just such an experiment was being carried on board Columbia's last flight.

But wait. Didn't NASA announce in 1999 that it had developed a new flu drug in space? Yes it did. But the crucial crystals were not grown in space at all; they were grown in Australia.

Most ISS goals have yet to be fulfilled

The ISS mission statement that appears on NASA's space-shuttle website also promises advances in tissue culture, as well as "better metal alloys and more perfect materials for applications such as computer chips". All of these have yet to materialize. The experiments in fundamental physics that are listed on the site are also scheduled for future unmanned satellite missions, at a fraction of the cost; the same can be said for remote monitoring of the Earth.

But the part of the statement I like best says that "industries will participate in research by conducting experiments and studies aimed at developing new products and services. The results may benefit those on Earth not only by providing innovative new products, but also by creating new jobs to make the products." Perhaps I should not be so cynical. After all, research on the STS-95 shuttle mission in 1998 did give us a new scent, used in a perfume called Zen.

The ISS is a pitiful flagship for international collaboration.

In 1993, when the US Congress was about to pull the plug on ISS funding, it was suddenly announced that the space station was not about science at all, but about fostering international goodwill. (Or to put it another way, the United States felt it would keep unemployed Russian nuclear scientists out of mischief.) It does all seem to be rather a costly exercise in international relations. Then again, why bother making the effort to find agreement over arms control, global warming, poverty or trade, when you can foster global harmony with the sight of an American and a Russian astronaut fixing a circuit board together in space?

The ISS is an embarrassing anachronism that feeds on vacuous myths.

Today the ISS apparently has a new mission: to prepare us for colonization of the Moon and manned exploration of Mars. OK, so it is only 250 miles away, which means we've got 34 million miles to go, but you have to start somewhere. It is a symbol of the, well, the destiny thing... the Columbus spirit. Maybe that's right. Space may be, as the Reagan administration declared, "just another place to do business", and Columbus was similarly bankrolled by the Spanish court for commercial purposes. But somehow, I can't help thinking that King Ferdinand and Queen Isabella got better value for money.