I have strong suspicions that most micro-organisms that are claimed to be captured at high altitude are in fact the result of lab contamination back on the ground or contamination off the balloon or experiment package. Even if you could efficiently sterilise both, they are still going to ascend through the troposphere on the way up, which is laden with bugs anyway. I give an example below which i is mainly a microbiological argument.
Finally, sampling missions to date, as far as I have read so far, made no allowances for atmospheric pressure - I can't believe bacteria grow the same at 0.01 bar versus 1 bar on the ground.
So, to sample at high altitude, IMHO, you need:
A) to be able to re-sterilise in flight after passing up through the troposhock, or jettison some sort of disposable cover to reveal a sterilised sampling vessel
B) carry out your biological experiments whilst at altitude to rule out post-flight lab contamination
C) find some way of preventing air flowing from the balloon canopy or experment gondola from reaching the sampling vessel
D) capture the samples completely airtight so they stay at 0.01 bar for instance throughout the descent back to the ground and/or (B)
Here's my preliminary design ideas for each point as a molecular biologist:
A) use a germicidal UVC light source such as UVC 260nm LEDs, to both blast the sampling port and any pipework for the molecular biology within.
B) my forte - I automate labs terrestially for a living. I'd like to make a miniature pipetting robot
D) do (B) but be very careful of vapour pressure at this altitude - water and reagents will boil at 3-4'C. Stray heat from the electronics. Might be enough to boil the samples dry therefore. It might be safer to pressurise the samples just a little bit, say 10s of mBar, with something inert like Argon.
What about (C)?
Well, this is what I thought of whilst washing up! Could you generate a vortex ring state around your sampling port? As I understand it, VRS is a toroidal body of moving air that self-circulates within itself and is therefore stable over distance. This is the principle behind "air bazookas" which are fun toys for blasting friends with intense bursts of air from some distance away. I think smoke rings are VRS' for instance. Wikipedia has quite a good description!
If you could generate essentially continuous or pulsed VRS, you could essentially exclude air currents and contamination from elsewhere on the balloon. Since VRS' travel in a stable manner over distance, this presumably prevents any recontamination from eddies nearby the balloon. Effectively you might have a "clean" sampling corridor down the middle of the toroids?
You could achieve the same thing with a long pipe, but then - how do carry the weight and how do you sterilise the pipe? And presumably you have to stick it out sideways, not downwards, since most contamination from the balloon will drift downwards under gravity (presumably?)
I suppose another alternative could be to blast a sample container free - maybe one that would self-sterilise itself and then take the sample. Think maybe a sphere studded with UVC LEDs shot from a mortar in the gondola? You could either retrieve it on the ground, reel it back to the gondola somehow, or carry out the biology in the container.
If this begins to sound heavy or power-hungry, IMHO we should not shirk from that. We could easily fly bigger balloons for longer, for instance by adding a transponder for air traffic worries, and maybe a high-density power source - I had in mind something like a Wankel engine adapted to work at high altitude. But that's another discussion!
Anyway, those are some initial ideas!
(I should really be in bed but have batted this out over some OJ, chocolate, a cup of tea and a shower!)
Microbiological details :
For instance, Griffin et al Aerobiologia (2008) 24:19-25 claims to have
found non-sporulating bacteria in the high atmosphere. Non-sporulating?? That doesn't make any sense. I wouldn't be at all surprised to find hardy spores from sporulating bacteria. But non-sporulating?
Also, they claim they bacteria didn't show up until they'd cultivated the bacteria for several weeks. Personally, I feel any agar plate or equivalent will grow *something* after long enough, no matter how much you autoclaved the media.
Finally, they made no allowances for atmospheric pressure - I can't believe bacteria grow the same at 0.01 bar versus 1 bar on the ground. Surely an aerophile will just roast itself with massive oxidative respiration? (Unless there's negative feedback regulation for occasional excursions to lower altitude... Interesting...)
PS and finally, how did I find out about VRS?:
A wikipedia binge as follows:
Iranian satellite launch
Iranian space program
Iranian hostage crisis
Failed american rescue mission
VSTOL Hercules C130 designed for above
V22 Osprey tiltrotor (also VSTOL)
V22 Osprey crashes
Vortex rotor state! (Has caused V22 crashed due to VRS from the rotor blades).
VertiTech: a miniatured robotic system Ol has been dreaming
of (short for Vertical Technician.)