The article is pretty easy to read. Except the word "diatom frustule" (whatever the heck that is) it doesn't use a lot of jargon, or have any difficult math or anything. But let me briefly summarize, anyway.
The scientists launched a weather balloon in to the upper atmosphere. The balloon was a carrying a sampling device which they could remotely open and close to sample lifeforms in the atmosphere. When they opened a door in the sampling device, air could come in, and any particles could get stuck to sampling strips that could be analyzed later.
Using a scanning electron microscope, they found a "diatom frustule" attached to one of the sampling strips. Apparently that's part of some kind of unicellular organism. They suggest it might belong to the Nitzschia species, but that it definitely looks similar to terrestrial versions of diatoms, and that molecular biologists in the area could probably identify it. Here's what they say in the paper:
On one stub was discovered part of a diatom which, we assume, is clear enough for experts on diatom taxonomy to precisely identify. Similarities with a broad class of diatoms belonging to the Nitzschia species point to a probable tentative identification with a terrestrially known similar organism.They ran a control experiment, where the sent the balloon up in to the air with all the sampling strips, but didn't open the door. They didn't find anything that time. So this thing definitely entered the balloon, they say, between 20 and 27 km above the earth.
So how did it get there?
It couldn't possibly have gotten in to the atmosphere by any normal means. They suggest a volcano as one possibility, but there weren't any volcanoes in the area any time recently. Calculations show a predicted falling time of around 6 hours for particles of that size at that height, and the last volcano was years ago. So since it wasn't a volcano, it couldn't have been anything else. Since it's so impossible for the particle to have risen that high in to the air -- really, just sillily impossible -- then it must be the case that the fragment of a Nitzschia species of diatom originated from the vacuum of space.
They suggest that the diatom was enclosed in water on a comet, and that as the comet entered the atmosphere, the water melted and released the diatom, which was then collected by the weather balloon. Here's their own wording:
While an Earth–bound origin for this diatom fragment may be invoked in order to meet criteria of parsimony or conservatism, we argue that since no major violent volcanic event or other atmospheric event occurred close to the time and place of sampling, the diatom fragment shown in Fig.1 must most plausibly have come from space – thus establishing consistency with theories of cometary panspermiaSounds reasonable.
Curious, did a meteoric event occur close to the time and place of sampling? Were there any comets there? Maybe there's no way to know that.
In one press release, the author is quoted as saying:
“Of course it will be argued that there must be an, as yet, unknown mechanism for transferring large particles from Earth to the high stratosphere, but we stand by our conclusions. The absolutely crucial experiment will come when we do what is called ‘isotope fractionation’. We will take some of the samples which we have isolated from the stratosphere and introduce them into a complex machine – a button will be pressed. If the ratio of certain isotopes gives one number then our organisms are from Earth, if it gives another, then they are from space. The tension will obviously be almost impossible to live with!”So they're going to do more tests to determine where the sample came from. That's good.
Here's an idea for a possible mechanism for transferring large particles from Earth to the high stratosphere: weather balloons. Of course, they mention this in the paper, but dismiss it. It's just that impossible for diatoms to get on the weather balloon at any stage during the lift-off process, or to ever get from the balloon and in to the sampling device just below. Plus the sampling unit is covered to prevent that; according to the original article
The sampling apparatus was protected from downfall of particulate matter from the balloon by a cover.It's much more likely for terrestrial life forms to end up on comets from outer space and break off in the stratosphere before falling to the level of the air balloon, than for terrestrial life forms to get stuck on the balloon surface before falling to the sampling unit on the balloon.
For some reason the cover preventing downfall of particular matter works for the balloon, but not other things like comets. I'm sure they have scientific explanations for that.
Or are these terrestrial life forms? In another interview, the principle author is quoted as saying:
"The organisms are not usual," said Professor Wainwright, who works at the University of Sheffield’s Department of Molecular Biology and Biotechnology. "If they came from earth, we would expect to see stuff that we find on earth commonly, like pollen."
"They're very unusual beasts, not your normal kind of life from earth."
which, of course, directly contradicts his published claims. But maybe he changed his mind? Or maybe he means that it's probably a Nitzschia diatom with probable terrestrial identity, but the unusual kind that doesn't come from earth. I don't know.
Strange stuff. Definitely a revolution in science. We'll just have to see what later experiments turn up.