Thursday, April 30, 2009

Update on my vortex ring state idea

It occurred to me yesterday that a VRS "corridor" idea has an obvious flaw, which is that the VRS toroids will expire eventually and then release their presumably contaminated air from the balloon and gondola into the "corridor".
However, this can be fixed by sterilising the air in the VRS' as they are generated, for instance by UVC LEDs. Is this possible? Even with air rapidly moving past the LEDs? We'd need to try experimentally.
If this begins to sound like requiring unfeasible amounts of power then it is worth remembering that actually, the sample corridor would maybe only need to work for a few seconds - after that the air samples would have been drawn in and be ready for analysis.
VRS is just one idea. Do you have others? Perhaps a "Self Sterilising Mortar Round" (SSMR) as described in my earlier post is better?
Let us not forget the obvious approach - a long pipe to stick out from the gondola. But how to make a Self Sterilising Pipe? (SSP). You can make flat packing or inflatable pipes (that's another blog!) to deploy during flight, but could you do this with the surface studded with UVC LEDs? Wouldn't this get really heavy and full of cabling? Maybe you could illuminate the pipe from the gondola with a very bright fixed UVC source - an LED or laser, sterilising it from a distance. But this might need to be very powerful... perhaps it doesn't have to be a UVC source at all? Coronal discharge is a potent sterilising agent as well (a company called Cerionx was trying this, as I recall). Could we build up a high electrical field on the pipe, just below that that would arc at high altitude? Is this a cool experiment in its own right?

We could perhaps try buying an "Air Bazooka" toy and seeing if the VRS' it generates can actually be sterilised by UVC LEDs. For instance, we could rig such a "Self Sterilising Air Bazooka" (SSAB - I feel like making acronymns tonight!) And then fire it continuously onto an agar plate with the LEDs turned either on or off. If you see a circle of fewer bacterial colonies where the VRS hit the dish, you'd know the air in the VRS was indeed sterile.
Do you think this would be worthwhile spending some of the NESTA cash on?

At the root of all of this are the questions: How far away from the gondola and the balloon do we need to sample? What are the winds at altitude? How turbulent? Do we need to measure this in flight?
Is there a fluid dynamics expert reading this? What is the safe distance beyond which any eddy bearing contamination from the balloon is unlikely to travel? Just how far from our balloon mothership do we need to go to sip pristine stratospheric air?


  1. I like the idea of the SSAB. But a few questions - how does it work ie is it a continuous stream or a series of rapid blasts? Could we autoclave one? Or sterilize it so that we know that its air and not coming from the innards of the toy.

    Inflatable pipe - I like this too - could there be a concertina that is sterilized as it is deployed with a closure at the trap end that could be sterilized just before its opened. That might save trying to do a long distance - would we get in to trouble trying to do a laser sterilization in case it went astray and CSI style hit a pilot in the eye....or is that a bit far fetched?

    I have also been thinking about measuring wind speed - I think this would be important and is something I am going to try and incorporate into my bacteria gathering at sea level and up a mountain.

  2. I think it would be a series of rapid blasts, but I wondered if you could have two SSABs concentric with each other and firing in turn for continuous VRS? I expect toy ABs you could buy would not be autoclavable but you could perhaps gamma sterilise them. The problem with any deployable structure I think is that if the balloon is assumed "dirty" then it could continuously recontaminate the pipe which could in turn recontaminate itself as stuff blows along its length. Thus pretty soon we need continous decontamination along its length. And doing damage to people is a problem - with the inverse square law and all that, the LEDs will have to be very powerful, especially at any distance. Elsewhere on the blog we discuss illuminating balloons from the inside for instance. This might not be feasible. We're talking thousands of watts per square metre just to be similar in flux for natural solar radiation - and anything alive up there must be adapted to this at least. Still, maybe a sustained dose over several hours will do the trick. We will need to test the canopy with some sample bug spores to see how we get on... Let me know how you get on measuring wind speed and direction. I think at high altitude we will need a "tell tale" - a weighted bob on a string that shifts in the wind - similar to the one used on the Phoenix lander on Mars last year (the Martian surface and our balloon flight have similar atmospheric pressures!)

  3. Because I'm a child at heart

  4. Actually, what I find very encouraging is that the smoke rings from the candle Bazooka propagated so far and so tightly. Perhaps this really might work! And this was a manually powered one to boot. I wonder though if you really can mount two Bazookas concentrically? Surely you can if you are far enough away from the annulus of the first one so you don’t interfere with the mechanism of the first one?