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Flying fish: the oyster toadfish is part of the first Neurolab payload, launched two weeks ago. Credit: NASA

US space officials hope next week to approve a second flight in September for the Neurolab space shuttle mission — whose first flight was successfully launched two weeks ago — to allow researchers to collect more data on how the nervous system adapts to spaceflight.

The US National Aeronautics and Space Administration (NASA) has already concluded that a reflight is “scientifically very worthwhile”, says Edmond Reeves, head of flight planning for its Office of Life and Microgravity Sciences and Applications. A decision is expected by next Monday (4 May).

The international Neurolab mission, which includes participation by the National Institutes of Health and other agencies, is widely regarded as one of the best-designed space research missions ever flown.

A reflight would cost “tens of millions” of dollars, says Reeves, excluding the price of the shuttle launch. NASA and the other Neurolab participants — Europe, Japan and Canada — are already discussing how these costs should be split.

For its part, NASA would redirect funds intended for other microgravity and lifescience research activities this year, as well as some funds from the shuttle account. To save time and money, the Spacelab module would be reflown with the same laboratory equipment and the same core crew of astronauts.

Only the scientist ‘payload specialists’ might change, Reeves says, as it could be useful to have different test subjects for some Neurolab investigations. It should also be possible to fly some experiments that were not included on the first flight.

The space research community is eager for as many ‘gap filler’ flights as possible while waiting for the space station to be completed in 2003. Another such flight is planned for October, but room for scientific experiments is limited. Commercial research payloads will take up 60 per cent of the US half of a small laboratory module provided by Spacehab Inc. A second ‘gap filler’ mission in 2000 could fly a larger module, but so far there is no money for this.

A big uncertainty affecting the decision to refly Neurolab is the space station construction schedule. NASA managers hope to learn during a joint programme review in Moscow this week whether a key Russian ‘service module’ — which keeps the station in orbit during the early assembly phase, and provides the living quarters for its first crew — will be ready for launch early next year.

Russian officials have said that the module, the third station component to be delivered, will miss its December launch by three or four months. But even that is uncertain.

An outside review team painted a gloomy picture of the station's future in a report last week. According to a task force set up by NASA's outside advisory council at the request of the agency's administrator Dan Goldin, the US investment alone will climb from $17.4 billion to $24.7 billion, and assembly will take between one and three years longer than NASA believes.

Space station managers continue to be too optimistic about schedule and finances, said the report, and NASA will need as much as $250 million a year more than it has requested to keep the programme on track. “Budget and reserve levels have been, and continue to be, inadequate for a program of this size, complexity and development uncertainty, despite NASA's past contentions that the total funding level is adequate,” the report said. The primary — but by no means the only — threat to the project is Russia's unreliability, according to the task force.

The report's conclusions were made public last month. But NASA's reaction has been muted. In Senate testimony last week, Goldin said only: “While we may differ on the level of criticality of specific issues raised, I believe the [task force] has captured important risk areas for NASA and the [space station] programme to consider.”