Thursday, April 30, 2009
I also met Oliver on the NESTA Crucible 2008 (can't be bothered to hunt for the links, just use Mel's).
My role on the team is minor, as is the amount of time I will have free to fill in this blog thingy. Especially compared to Ol as you can see.
I have experience in 3D computer modelling - the use of the computer to generate and manipulate shapes. I have also played around with Rapid Prototyping / 3D Printing and the general extraction of 3D geometry back out of the computer and into the physical world. I have mainly worked in the building / architectural field, but that's just a question of scale. (And I wouldn't put it past Ol to decide he wants to launch a whole Lab building into the stratosphere one day...).
So I've agreed to help produce some of the more bespoke parts for the project by modelling them to great accuracy in the computer and then 3D printing them. I'm relying on the others to tell me what they need. But you've got to admit that printing something out one day and launching it into the sky the next is pretty cool...
It'd have to be a pretty big chamber but we could settle for testing scale models of things!
Probably the only people who have chambers like this are in aerospace. Often they are for testing satellites etc and have lamps to simulate the sun, which would actually be very helpful for us. But pricey?
Due to the danger of implosion it wouldn't be something to jerryrig I think!
The alternative is to just fly stuff and hope it works. Actually, this isn't a bad way to test IMHO - if you could fly the balloons really frequently and if you could find out what had gone wrong. At the moment, you need to track the balloons all the time, report this to Air Traffic, buy insurance etc.
Perhaps the answer is heavier balloons with transponder for air traffic worries? Actually not so pricey (FAA approved transponder and battery for about £2K, say 2.2kg total).
A fan or something could be used by might be very ineffective in the high stratosphere. But we could test this... If we had a hypobaric chamber...
Since the gondola canopy has to have a sampling port - an invagination to the gondola itself insiden if you will - effectively the gondola can be prepared and attached to the port on the canopy with the canopy inside out, which can then be turned right side out and invaginate the gondola within it!
But would cyclo-olefin take this much punishment? Who makes it anyway?
Oooh! We could have a reusable balloon? Instead of bursting it we could incorporate controllable valves? After all, we need to have our custom cyclo-olefin job made anyway...
For those of you who don't know, balloons usually have to return on command, for instance by firing a small squib to burst the main canopy.
The gondola within could be left "dirty" or could be extensively sterilised groundside. The trick throughout is to sterilise everything exposed to the air in flight - main balloon canopy, lines, gondola canopy - in flight! Hence the LEDs.
Any cyclo-olefin manufacturers out there?
Even a small balloon of either type could perhaps be used as a self-sterilising sample-grabber that would rise separately of the main gondola, like the mortar idea I posted earlier. Since ground contamination concerns are still valid (see earlier post), the sampler would then be reeled in for in-situ analysis - somehow?
What would its safe viewing distance be? Could this double as a beacon for nighttime flights?
Would pulsing the UVC source be more effective than continuous illumination?
Blacklight type fluorescent strip lights or LEDs?
Is cyclo-olefin impermeable to helium? (At least long enough to last the flight?) How much does it cost? Can we have a balloon made out of it? Where would we find a really brilliant UVC source?
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?
Tuesday, April 28, 2009
Comments from Ionic fluid experts welcome!!
All this balloon talk reminds me of something else I thought of last week which got lost in a hectic weekend.
I have a colleague who makes nanocrystalline porous films and I wondered if these could be used to make a truly UV-transparent material for our balloon radiobiology experiments. Even quartz for instance absorbs more and more into the UVC at any mechanically feasible thickness. It's no longer transmitting a representative solar spectrum.
I wondered if you could seal the pores with a very, very thin film of quartz, cyclo-olefin etc - something nice and UV friendly and even more so due to being extremely thin. The pore structure would provide physical support, and the pores would be wider than half the wavelengths of UVC, and so wouldn't interfere with transmission. For that matter they would be
bigger than half a wavelength of any part of the solar visible spectrum of any possible biological relevance.
I had also wondered if you could seal the pores with a liquid, which would wick into the pores, but I couldn't work out how you'd stop it boiling off at high altitude.
My colleague gently poured cold water on the thin film idea, saying it was in fact very hard to do; the thickness and coverage is very variable.
However, he hit upon the same idea as me - a wicking liquid - but as a highly capable chemist he knew which to use, at least conceptually: An ionic fluid. These can be long and complex molecular chains and as such essentially have no vapour pressure, hence no evaporation. Again, since they
are long and complex, they have short-range order and are unlikely to absorb in the UV.
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.)
Monday, April 27, 2009
Friday, April 24, 2009
My name is Melissa Grant and I don’t have that many professional activities outside of work - but I do like blogging (so you can keep track of my other hobbies), they keep me pretty busy at the Dental School with projects looking at making new toothpastes that fight inflammation.
Ol and I are doing this project after we met at NESTA’s Crucible Labs last year (2008) and won some funding to do this project - needless to say its an amazing opportunity! Through this blog I hope to document what I am up to - what research is going on and hopefully the outcome of the experiments.
Click here for the Society for Chemical Industry. Since 2002 I have been the Chairman of their London Section (soon to be renamed the London Regional Group), with a responsibilty to provide lectures and events for over thirteen hundred members.Click here for the University College Union. I am an active union member and am a member of the MRC Committee.Click here for previous events in my career, such as my time at NASA and Reading University Why not email me at firstname.lastname@example.org ?