By Richard Black
Environment Correspondent, BBC News website, in Vienna
America's astronauts may have been the first to plant a flag, drive a buggy and play golf on the Moon.
Planting flowers, however, was not on the Apollo agenda.
Could Europe beat the mighty US to that particular goal? One small seed for man, one giant branching-out for mankind?
In fact, according to the European Space Agency's Bernard Foing, it is more likely to be a bulb than a seed - perhaps even that most European of plants, a Dutch tulip.
"They bring their own nutrients with them, you don't need any resources from the soil," he told me on the fringes of the European Geosciences Union (EGU) conference last week.
"Also, we have looked at other types of plant like the mustard plant Arabidopsis; it's a very resistant plant, its genome has been fully sequenced.
"So you could do experiments where you see what does it take to adapt it to another planet, where are those characteristics encoded in the genome, and so make hard science but also make technical applications of what types of plant could be engineered to better survive in these conditions, and what type of plants could be engineered to adapt to very extreme conditions, even having the possibility later to find applications on Earth as well."
It is, at least, an intriguing vision.
Dr Foing's formal job title within Esa is "chief scientist", and he comes with formidable pedigree, not least being the leader of Esa's pioneering Smart-1 mission.
But he could equally well have inscribed on his business card "Chief Space Visionary, Europe".
Say it with flowers: could tulips from Amsterdam grow on the Moon?
The Moon tulip is just one example of the futuristic, fun and possibly even feasible ideas dreamt up in his think-tanks headquartered at Esa's European Space Research and Technology Centre (Estec) in the Netherlands.
Also on the drawing board is a robotic lander.
"Ten years ago, we had a lunar studies group making a feasibility study and design for a lunar lander at the equator or the pole," Dr Foing recalls.
"But at that time it was very difficult to design a mission at low cost, because a lot of technologies needed to be developed, and also we didn't know what the polar region of the Moon looked like.
"With current missions we have much better knowledge of the polar regions as a site where we could search for ice; and also with Smart-1 we have identified some 'peaks of eternal light' where we would like to land - these are areas near the poles of the Moon which have sunlight all the time, even in winter."
Landing at one of these sites would guarantee solar power all day and all year round.
Various working groups are now discussing what should be done to take best advantage of these sites; what equipment should be carried on a robotic lander, how far rovers should rove, how to plan missions so they go from the safest operations to progressively more risky ventures carrying potentially greater rewards?
Currently on the drawing board is a lander weighing about 180kg which could be launched at relatively low cost.
Out of this lander would emerge a rover designed to stray no more than 10 or 20km from the landing site.
Between them, the lander and rover would perform a range of experiments - analysis of rocks and soil, measuring radiation to see if humans could survive it, examining the Moon's inner structure.
The solar-powered rover would explore areas of 'eternal light'
This is also the phase when lunar soil would receive its first gift from the Amsterdam tulip trade, perhaps planted inside a plastic biosphere with carbon dioxide on tap.
Having finished its domestic duties, the vehicle would then rove off to the edge of a polar crater, which are shadowlands replete with temptation.
"There are ideas that in the permanently shaded reservoirs at the poles you could have ice reservoirs which have been delivered by comets," said Pascale Ehrenfreund, professor of astrobiology at Leiden University in the Netherlands.
"Cometary ice is dominated by water ice, but always contains other molecules such as carbon monoxide, carbon dioxide, traces of methanol, traces of HCN [hydrogen cyanide]; and then in those areas you certainly have quite a bit of radiation which is probably partly destroying that kind of material if it is present, but it is also creating more complex structures."
Would the rover descend into the crater or just peer over the edge? Would it launch a much smaller tethered rover - a "nanorover" in the current Esa phraseology - or fire harpoons down into the dark ice?
All these possibilities are floating in the intellectual ether, and Bernard Foing's various working groups are in discussion with scientists in European research institutions over what instruments should be priorities for the payload and what delivery systems are needed to get them there.
But he wants a decision soon, ideally during Esa's ministerial conference in 2008; that could lead, he says, to a launch between 2012 and 2014.
But what is it all for - is the Moon really that exciting any more? Haven't we been there, planted the flags, bought the Apollo t-shirts and brought back the Moon rock?
"Certainly we have 365kg of Moon material on the Earth, but I think there are many scientific aspects still to be achieved there," said Peter Falkner, head of Estec's planetary exploration studies section.
And there are technological objectives which go beyond a Moon visit. Just as Smart-1 has tested an ion drive for long-distance propulsion, a lunar lander could also pilot equipment and procedures which could later find a use on more far-flung missions.
"Certainly there are several technological issues to be solved," observed Dr Faulkner, recalling the successful landing of the Huygens probe on Titan and the less successful end of the Beagle 2 Mars mission.
"So far in Europe we have demonstrated landing on a body with an atmosphere successfully, on Titan, and there are several reasons for the failure we had on Mars.
"On the Moon there is no atmosphere; you need a fully controlled landing, so your orbital velocity has to be reduced with a chemical engine. At the moment we do not have all this technology completely available in Europe, so this is what has to be developed."
At this point the cynic says "Well OK, but Nasa did it in the 1960s, and with people on board. What is the rationale for getting where the Americans were half a century earlier?"
One reason is that Europe, being a late starter in space, is determined to catch up on some core technologies.
Another is that it sees a diversification in space priorities; Esa will not be the next agency to put humans on the Moon (currently that appears to be a race between the US and China); but with some innovative rovers, landers, harpoons and other gadgets, it may be able to do things which Nasa and the Chinese space agency will not.
And the tulips? Bernard Foing sees them as a part of a sequence of research projects which will take ever more complex organisms to the Moon; bacteria first, perhaps, then plants, then animals, though probably not four-legged followers of Laika the pioneering Soviet space dog.
"We have to look at all the different social and ethical aspects of that. But I think there are a number of small animals like insects where you could learn things - spiders on the moon?"
It is perhaps interesting in an era when there is so much debate about the ethics and value of using animals prior to humans in medical research to see the different approaches agencies are taking to something involving greater risks - Moon travel.
While the US is apparently content to send humans first and perhaps exclusively, Europe seems set on a different track, using other organisms, both for the general and specific information they can yield.
"I would be interested to see how a spider would react in a different gravity world," said Bernard Foing, "and also some of them are very resistant to radiation.
"So there are some insects which could be of use - or maybe, and this a bit more speculative - a mixture of insects and robotic insects."
The tulips, however, will undoubtedly be natural - an symbolic flowering, perhaps, of a distinctly European approach to space science.