By Jonathan Amos
Science reporter, BBC News
Scientists from different fields carry out microgravity experiments
British scientists wanting to pursue microgravity studies have only a few days left to express their interest in a potential new research initiative.
The UK withdrew from the European Space Agency programme related to experiments in "weightless" surroundings in the early part of this decade.
Now, space officials are assessing the level of enthusiasm for a renewed co-ordinated research effort.
Scientists have until the end of the month to make their feelings known.
There are no promises being made at this stage - but the officials say that unless scientists put their hands up, microgravity research will forever remain a fringe activity in the UK.
Groups should register their interest at the British National Space Centre website.
"The problem is that people talk about the 'microgravity community' as if it's a single entity; but there's no such thing," said Dr Jeremy Curtis, who is looking after the BNSC call.
"People who do microgravity experiments cover a whole host of scientific fields - medical doctors, fundamental physicists, fluid mechanics experts, materials scientists, etc.
"We want to know who's out and who's interested. If we don't know who these people are, we can't even begin to organise anything."
A change of direction is unlikely to see the UK suddenly opt into Esa's multi-million-euro European Life and Physical Sciences research programme (Elips), but it could conceivably see the Research Councils dedicate some cash towards the activity.
At the very least, it would pull the various interested scientists scattered across academia and industry into a co-ordinated and networked grouping.
Studying systems and processes in the absence of gravity gives scientists a unique perspective.
In an Earth laboratory, gravity pulls hard on everything; but if the notions of "up" and "down" can be removed - even for a few seconds - then some unusual things start to happen.
Gases and liquids that are heated do not rise and sink as they would normally do; and suspended particles do not settle out into neat layers of different sizes.
By removing the "mask" of gravity, it then becomes possible to study the effects of other forces more easily. The knowledge gained is expected to have significant impacts, from developing new vaccines and crops, to understanding how the interior of the Earth behaves.
The International Space Station is perhaps the best known dedicated weightless laboratory, but it is not necessary to go into orbit to do microgravity research.
Simply dropping an experiment from a 150m-high tower will give a few, useful seconds of weightlessness.
Slightly longer periods of 20s or so are possible on aeroplanes that fly a series of parabolic arcs in the sky.
Dr Gail Iles, a research fellow with the European Space Agency, uses this method to evaporate metals. This helps us understand how "intermetallics" behave. These are strong, lightweight combinations of metals that have great potential in the aero, auto and energy industries.
"I use a small furnace to make the samples. It is in the periods of microgravity that the particles grow in a different way. I'm making just fractions of a gram - they're really just nanoparticles."
Nonetheless, the tiny samples are invaluable because gravity has not been allowed to bias the metal structures. These samples can then be used as models to help improve the methods used in Earth-bound industrial production.
Dr Iles is looking for support to bring the European Zero-G A300 Airbus to Britain. This plane, which is normally based in Bordeaux, is run by a commercial subsidiary of the French space agency.
"There are different types of flight," she told BBC News.
"If you want the full two-week campaign - that's a week of preparation, loading and testing; and then a three full days of flights with 31 parabolas per day - then it's approximately 750,000 euros."
Dr Iles envisages a flight campaign running out over the North Sea or off the coast of Brittany with a cabin full of UK scientists doing a slew of national experiments.
The last UK review of microgravity research was undertaken by Professor Bill Wakeham in 2002. His panel set out the options available to British science at that time - from joining the space station programme to operating more limited endeavours here on Earth.
The review recommended that Britain join Esa's Elips programme at the minimum level, which at the time would have cost about £3m.
However, the then government and the Research Councils decided the priorities for science funding lay elsewhere.
"We have a user-driven approach to space," explained Dr Curtis. "It's a very practical way of organising things: if the user doesn't want to pay then clearly it's not worth paying for. But there are occasionally gaps which form as a result of that approach.
"You can't organise science as a continuum; there have got to be a few boundaries between responsibilities. But it's at those boundaries that the microgravity opportunity founders."
( The deadline for submissions was extended until Friday 7 August)