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Solar power options for a HAB II

This is for a balloon flight.
Solar flux is considerably higher at stratospheric altitude and there is much less cloud cover, so solar is a more reliable option.
Matt and the crew have launched solar powered balloon payloads before - but never mechanical stuff...

The idea of the relays would be to switch from the solar arrays to a conventional battery if the solar supply falters (so I guess I need a double-pole relay)

The next trick would be how to power the relay direct from a microcontroller, since the pins on say, a PICaxe give only 10mA. We need a relay that can handle either the 1A or so from the solar array or the massive ampeage from a battery shorting through a SMA (offscale on a 30A multimeter!). But relays often need 100mA or so to switch... So we probably need a transistor to switch on a 100mA current from a PICaxe pin.

Why do we need this?:
At Black Rock we ran our battery ragged well before landing - the last coms I got was just before the balloon burst (when we were near Frog Pond), which was only about 90 mins (about half way?) in. The intense cold probably played a part but we also had a constant power demand of a couple of amps at all times anyway.

The LiFePO4 battery I got lasts longer but Matt said they don't like balloon flight conditions at all.
So any other options would be worth trying.

It looks like the cost driver for solar arrays is voltage - say £70 for a 12V, 5W, which is a measly 400mA or so. For SMAs we only need amps, so a cheap low V, high A array might buy us something.

It's a bit the same with battery charging. For a 6V battery we need a 6V array and a decent ampeage to get a decent charge rate, which means in practice an array too expensive and too big to fly.
Besides, as far as I can tell, the only practical battery for trickle-charging from a solar array is a lead-acid one, which might burst at high altitude (since they are sealed to prevent leaking) and are bulkier. They are no good burst-wise for rocket flights either, for reasons HAB 1 well knows!

So, it might be fun to play with solar to extend the balloon flights, but have a relay to switch back to battery if needed.

In general, good DC sources for use in the field would make a lot of sense, since as it was we were constantly running AC inverters off car batteries to power power supplies to supply DC to power laptops and so on... Whereas a 19.2V battery and/or solar array could have done it directly. We spent a lot of time angsting over generator resources etc similarly. It might also be worth digging up an old low power PDA, say an Atari Portfolio, for the serial coms... Don't really need a laptop at all! Would run for hours on AA batteries...

Ol

------Original Message------
From: Paul
Subject: Re: Ideas for switching low volts, high amps?
Sent: 22 Feb 2011 20:01

I think a mechanical relay would be the only way to do what you ask. Maybe not suitable for rockets (acceleration might trigger it) but ok for balloon.
But you could maybe switch each separately (0.4A) and combine them afterwards, which might get you back into the FET range.
Solar sounds a bit unreliable though, given there's no real problem with a battery? Solar usually gets combined with a battery / large capacitor anyway to take out the peaks & troughs...

P.

On 22 Feb 2011, at 19:22, opeyer@nimr.mrc.ac.uk wrote:

> Can I ask you an electronics question?: What is the best way to switch a low voltage but at highish current? I'm looking at about 0.45V, 1.2A. I've played with the SSRs before (basically big MOSFETs) but they need at least 3V for the circuit being switched. Same for Darlingtons. Should I use a mechanical relay or is there something else?
>
> This is for a H.A.B advance project - I found some cheap 0.45V, 0.4A solar cells so, intriguingly, three of these in parallel might be enough to trigger a SMA in good light. SMAs only need current, not volts.
> Quite big, expensive solar arrays - enough to charge a battery for instance - seem to be high volt (say 12v), but not necessarily high current. So by contrast we might be able to do a solar-powered HAB quite cheaply?

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Re: astrobiology sterility vs disinfections

Hi Mel,
H2O2 is stable if stored correctly - it's been used as a storable rocket fuel oxidiser for instance. However, it can be broken down by an inorganic catalyst.... Perhaps we could inject, say, a palladium slurry instead of catalase?
But it's all just more and more plumbing!
Catalase is a much more efficient catalyst for breaking down H2O2 (hence it's name) so it would be fun to see how Catalase, Bugbuster and TwistDX co-exist! Or Palladium, come to that.
Best
Ol

Hey Ol
does hydrogen peroxide have a relatively short hald life? could we take advantage of that? or will the cold prevent in breaking down by itself?
M

astrobiology sterility vs disinfections

Hi Mel,
If I can tear you away from Fluxx for a moment, what do you think of the below?:
Basically H2O2 is the gold-standard for astrobiological decontamination, but can we do this in flight?
Are we getting closer and closer to the minirobot idea?
(I.e lots of things to pipet so a pipetting robot not valves?)

Best

Ol

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Many thanks, Lynn - if we tried to disinfect a system in the field or during flight (my long-term ideal) we would need to flush out or neutralise the H2O2 before adding reagents (eg TwistDX etc). The question then is whether the reagents can tolerate the presence of Catalase etc. Unless we need to flush out the Catalase etc too...

For trying to sample at altitude, something like Catalase might be problematic since the relatively high torr O2 released might nuke anything in the sample (since it would have evolved in a far less O2 -rich environment)

Perhaps this protocol is best used for in-the-lab sterilisation? I have often thought that actually we have access to a lot of plasticware that has been gamma-irradiated (the gold standard for being sterile AND is DNA-free, which is a separate criterion) and we could then try to sterilise plumbing etc (eg Tygon) with H2O2?

This is somewhat what I had in mind for this summer's HAB device but in practice the syringes etc needed too much fiddling to mount them sterile. I tried a ethanol flush during the rocket launch preps but that's a moot point now :-O ;)

Ol

------------------
Fw from Lynn

Alonso

I did conduct a literature search on Hydrogen Peroxide for spacecraft cleaning.

As noted for astrobiology/planetary protection for the mars missions of the 70s Solutions of 3, 10, and 15% hydrogen peroxide were found to have pronounced bactericidal effects, as a function of time of exposure, on sporeformers and nonsporeformers isolated from spacecraft. Find the attachment, applmicro00028-0236

It appears the UMS should be cleaned with the least toxic concentration 3% as exposure time can be long 4 hours.

The disinfection Nov 2008 guide has a selection of agents for disinfection listed if H2O2 cannot be used.

I hope all is well

best
tony...

Computer autopsy

Much has happened since our last posts to this blog, to be documented online soon.
This is a quick announcement to say that our bruised and battered flight computer has been sent back to its manufacturer for a computer autopsy. Fingers crossed!!
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I'm about to go to the desert!

I'm about to go to the desert!
Somewhat crestfallen - could not get my experiment to work properly due to a last minute electrical problem.(On wednesday it almost caught on fire!!)

But I will fly it on balloon anyway - I'll be able to talk to its computer using a special radio link whilst it is flying; that is still pretty cool! :-)

I am hoping I can get it to work during the week and do some experiments on the ground too - that will be quite interesting in such a big desert (is there anything alive there?...)
So I will try to enjoy everything even if the actual flight isn't perfect.

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Final preparations

The last few months have flown by and we haven't had a moment to update on our progress on the blog. Ol has been flat out, pulling all nighters to finish the device, which you can see in the picture. There have been nightmares about reagent compatibility and he has manged, with almost unbelievable cunning, to fit four syringes in to the device to pipette in the required quantities of liquids in the right order. Paul and Ol have been doing all kinds of things, remotely from Canada in Paul's case, to ensure everything will work.
We have also run a competition with NESTA and NASA for 2 students to come with us to Nevada to fly the device - welcome on board to Joe and Rainbow. We had 120 applicants and it was really hard to chose even the last 6 finalists, nevermind the 2 winners! Rachel down at NESTA has been in an organising frenzy, sorting out logistics - accommodation, flights, food (you would never normally have to put so much effort in to camping, we're just going to not have a lot of water so many things will be tinned) and much more.
With only a few days remaining before Ol heads to NASA AMES we are thinking very hard about how to get our reagents to California with out breaking any laws, but also crucially keeping them all cool. Then Rachel, Paul, Joe and Rainbow will head out, getting a brief trip to NASA too, and then I'll go out last (hampered by a conference the week before!). 12 days in the Nevada desert - to fly the device as many times as is possible - on balloons and rockets! The people we're teaming up with are the Rocket Mavericks. We're going to the Black Rock desert - home of the burning man festival. There's no phone coverage and its very remote (austere as Ol says), so we're taking GPS and satalite phones and all kinds of wizardry - hopefully there'll be some good star gazing too.
We've also been in discussion with Kira O'Reilly and Anna Dumitriu for possible art interventions and collection of materials whilst on location in the desert. Currently we're thinking of making extensive diaries and trying to communicate with bacteria.

First ever HAB dream? New components!

I went on a HAB bender last night and ordered lots more components. Then he actually dreamt about them all night :-)
The first ever HAB dream? Unless one of you can better :-)

I have now ordered a batch of non-sterile syringes and tubing, and established a wiring colour scheme for the main circuits (it was getting confusing with 5V, 12V and 3.6V high Ampage components)

I spent some time agonising about incubation temperatures for the TwistDX reagents and in fact if we can't get it to work, we could always test at ambient room temp to start with. Having said that, I have bought:

A professional combined probe and infrared foodgrade thermometer - will try both approaches. I wanted a probe or as small as possible otherwise the thermal mass of the probe ends up setting up the sample temperature and not the other way round!
As it is, the chamber looks like being at least 12mm long to accomodate the probe during testing. The probe hole will be sealed up later.

An IR spot might work - we need an optical window in the incubation chamber anyway for the PicoGreen measurement - but even the smallest spots on various instruments were over a cm, which seems unfeasibly big?

As a curveball, I will also try thermocolour plastic (like those forehead FeverStrips)

For the actual incubation, I will try resistive wire, maybe wound around the incubation. I have also found a small hotplate to sit the chamber on, and also a miniature water heater, and to go with that a miniature immersive water pump! (with water tubing wound around the chamber)
So it could be barheateresque, hotplatesque or central heatingesque!

Will keep you posted!

A little humour from Harold's Planet

HAB on a rocket?

HAB has now been invited to become part of the Clothos project,

flying similar payloads on rockets instead of balloons!

Is this our shortcut to a rapid flight??

http://www.rocketpedia.org/index.php/Clothos_Project#Science_.26_Instrumentation

The flight computer wired up - We're Gonna Need A Bigger Dining Table!

Flight computer has arrived!

Our lovely low-power PC104 Titan flight computer has arrived from Eurotech, complete with interface boards.
But what will we interface with now? A PIWB MAID? :-)
It is exhilirating to be involved in a project that evolves so rapidly and fluidly! A unique selling point of Crucible (R.I.P)

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Pump that balleen!

Hi Gareth,

Apologies for the delay, was on my Blackberry until now so couldn't
see your answers highlighted against my original text. Also my
thoughts on the peristaltic pump idea you suggest!

(Incidentally outstanding Googlemail targetted ads appearing alongside
this email, including the reseller for the MB2, a altitude/pressure
testing company and Fluigent!)

The U2 reference:
Griffin et al Aerobiologia (2008) 24:19-25 - Google it, it's free
For my severe doubts about this, please see my earliest posts on our blog:
www.highaltitudebioprospector.blogspot.com
Like you, I was suspicious about culturing conditions.
In fact - we'd like to do THREE things:
1 Attempt to collect for culturing - but trying to keep the samples
hypobaric all the way down
2 Carry out a bioassay IN FLIGHT so that nobody could say the result
was caused by lab contamination. Of course, it could still be
contamination from the balloon in flight - see the blog for agonising
about this (self-sterilising balloon anyone?). A suitable bioassay
would be amplification of 16S ribosomal genes with a fluorescent tag.
3 Try to match the two! (i.e see if you could culture something with
the same 16S sequence)
Love to add (4) which would be to try the same microfluidically!

Your later email: A peristaltic pump is indeed a very cool alternative
to a axial fan or a syringe/bellows type arrangement. Normal lab
peristaltic pumps are usually pretty massive affairs though (they have
to be to squish the roller against the tubing really tight). Hmmm....
how about a linear ripple peristaltic pump? Like an inkjet?
I.e a flat piece of tubing being squished in waves along its length to
accomplish the pumping. Might be easier to rig (the SMA actuators I
love pack a lot of muscle for their size and are very simple, but are
linear movement only really)
How fast could we run either type of peristaltic pump though? They are
intrinsically limited to the size of the tubing perhaps? It can't be a
really wide tube or it would be unsquishable (if the walls are thin
then it would quickly tear). If it is small then it takes a lot of
pumping for a given volume. But... I love the linear wave idea, can I
play with it? :-) OOOH that might work for a reel of tubing as well!
(just like you suggested parallelising a normal rotary one)

Looking at that weblink you sent us of the monster peristaltic, you
can apparently have peristaltics with 1/2" tubing!
Another maths experiment...
Let's assume 1cm tygon tubing, which we are more likely to lay our hands on
That has a cross section of about 0.5cm2
1L is 1000cm3
So, you would a 20m length of tubing to pump 1L
(1000/0/5 = 2000cm)

What I was even thinking was - the 16S or culturing reagents could be
INSIDE the tubing already - this would only weigh 1L=1kg in the
example above. But the tubing might be heavier...

(Let's check the axial fan situation further but Fred was adamant they
couldn't shift anything in low pressures)

The balleen idea is a beautiful comparison and I'm floundering how to
think it through biochemically (this is almost an unintended marine
pun! No, to be honest it's an intended one). What would be mixed with
what?
How thin can you make the film? Say it was 0.1mm thick.
Say the axle of the winding barrel for the 1km MAID ribbon I
postulated was 50cm across.
That would be a circumference of about 1.57m
So a 1km ribbon would wrap around the barrel about 637 times
637x0.1=64mm wound thickness

You could indeed either capture bugs on the film and try and grow them
on the ground, OR try to grow them in flight (paradoxically the better
bet perhaps, especially if you have a long flight, since the growth
conditions are most similar to the bugs' natural environment) - but
the problem with those two is you don't know what to grow them on. A
bioassay in the film itself might be best - i.e chamber 1 lyses the
cells, chamber 2 adds reagents, chamber 3 amplifies 16S etc. Mel has
already succeeded with this in the lab - see blog - but not
microfluidically! (Can you do all this in a 0.1mm thick film etc? 1mm?
I've always been fascinated by microfluidics from the outside but know very little of it's parameters!)

Oooh.... here's a lovely idea... I'm going to call it PIWB for Pumped by Inkjet Wave Balleen!
A thicker film with a pump layer made up of microfluidic channels that pump into the culturing or 16S channels - and the pump channels are pumped peristaltic fashion in linear waves, like an inkjet! All integrated in one.

But how do we activate the pump channels? Over to you Gareth!
(In your simpler passive sampler idea, how would you start the epoxy
sealant curing come to that?)

(Reading in the 16S fluorescent results from a PIWB MAID ribbon
(sorry!) is easier - you just reel it in again and scan the ribbon as
it comes back in, like a pianola.)

Night night and best wishes!

Olly

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Pumping at altitude

Been writing this all day in spare moments :-)

I got the basic bioaerosol numbers (I.e 1cfu/L at ground level) from the person (Fred) who builds the MB2 samplier, and I knew him through a science charity, so it was an interesting coincidence!

I think we need to work out some better way of getting the air through the sampler - according to my sums you'd have to pump a 50ml syringe for 60 years!!

Hmmm let's think that through
500ml - 6 years
5L - 0.6 years (219 days)
50L - 22 days, getting interesting
500L - 2.2 days (so a 1 day flight is worth it, the chances of finding something would be 50:50)

That's 500L per return syringe stroke - in say 10s, eqv to a continuous pump pumping 50L/s

The MB2, straight out of the box, is useless b.t.w, because its fan could never pull a vacuum Fred says - it is designed for ground level use whereas we need a pump that pump essentially to vacuum (I.e from 0.01bar, 10mbar, to something less than that, which to all intents and purposes is a lab vacuum).
Fred is quite interested in building us a hotrod version if we can think of a way round it though.

The problem with an axial-based fan design for a pump - what would first spring to mind - is that you can't really pump to a vacuum this way, which is what we are asking (see above)
In fact, electron microscopes etc use plunger-piston type pumps to pull a high vacuum - so not far off a syringe pump after all. You can't spin a fan that fast or that efficiently, but if you withdraw a given volume into a syringe or piston etc then you really have caught something in the barrel, even if it is very tenuous (ie.g 50ml at 0.01bar is eqv to only 0.5ml of sea level air)
Hmm can we cannibalise an EM pump? A surplus one perhaps? But likely to be heavy and high voltage. After all, all we need to pull is 10mBar to 1mBar, not from 1000mBar to zero (which is what the EM pump has to do)

How big a plunger would you need to shift 500L?

500L is 0.5m3

Let us assume a piston with a working stroke of 17cm - 0.17m (this is because this is the useful return stroke of the SMA actuators I have in the lab)

0.5/0.17 = 2.94m2
I.e, the piston has to have a surface area of 2.94m2 for a stroke of 0.17m to have a pumping volume of 0.5m3 (500L)

2.94=4pi(r)squared
0.74=pi(r)squared
0.23=(r)squared
0.49=r
So say 0.5m radius, I.e a drum 1m across - just about doable, especially if you have a bigger stroke (multiples of 17cm perhaps or a different mechanism altogether) for a smaller radius - OR multiple pistons

Who makes really airtight, sterile pistons? Life support machines perhaps?

The other alternative is to pull a chamber to vacuum on the ground, put it on the balloon, and then suck from ambient air pressure at altitude (e.g about 0.01bar) into the chamber. I have no idea how much a such a chamber would weigh though. Remember it needs to resist 1 bar of ground level air pressure whilst holding vacuum at ground level.

Could you pump it to vacuum in early flight, once the air pressure is less but still "pumpable", say 100mBar?
But is the pump heavier than the chamber?
And so on!!

Any ideas/maths to add my friends?
Can I pump you for ideas? :-)

Ol
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Very hard to happen upon aerophiles!

I'm writing this on my Blackberry so I can't check the aerophile literature right now! But here goes anyway:
I found out recently that the biodensity of airborne microorganisms, in colony forming units (cfu), is about:
1 cfu per 10l at ground level.
If same biodensity at altitude, allowing for lower air density:
Say 0.01 bar
1 cfu per 1000l
This is the same as a clean room :-O

How much air at this density would a detector 10cm2 square have to travel through to detect one colony?

10cm3 is 1l

Since 1 cfu per 1000l expected:
So, 1000 x 10cm cube=10,000cm
Or 100m air needs to be travelled through to detect 1 cfu at altitude
So 10cfu per km

U2 aircraft have flown similar transects of the high atmosphere.
A 1000km U2 flight could therefore theoretically detect about 10000cfu.
But only a single colony was detected during such a flight in real life using a similarly sized detector, suggesting that at the culturing conditions used in the experiment is question, biodensity is about 10000 less than at ground level, even correcting for altitude (and actually U2s fly slightly lower and atmospheric pressure is somewhat higher than 0.01bar). And that's assuming the single colony seen wasn't a ground contaminant.

If it was 10,000 less biodense then on the ground, then this means (allowing for altitude) not 1 cfu per 1000l but 1cfu per 10 million l !

But balloons fly far less far. If one opened a sampling port at final altitude, this suggests you'd need to allow the balloon to drift 1000km - OR pump 10 million L through your sampler.

Say you have a 50ml syringe pipetting up and down. 20 strokes is 1L

You would therefore need approximately 200 million strokes to detect one cfu. If each return stroke took 10s, this is 2 billion seconds
This is about 60 years!!

A long duration drifting balloon, flying thousands of kilometres, therefore seems more feasible.

One must also however be aware of sample port size.
The above calculations are for a 100cm2 detector (eg 10x10cm)
If your sampler had only a 1cm2 aperture, this would obviously be a hundred times less. Then the balloon would have to drift for 100,000km to detect 1cfu!

Could a large volume pump be developed, for instance using bellows?

Alternatively, could the sampler area be massively increased?
For instance, imagine a Massive Array of Inexpensive Detectors, MAID - a ribbon 10cm by 1km perhaps. That's 10,000 times the surface area of the original 100cm2 detector concept.
Then you would only have to drift for 100m to detect one cfu!

Of course there may be organisms that are hard to culture but which can still be detected by RT-PCR for instance. But these calculations certainly set an upper pessimistic boundary of what effort is needed to biodetect at altitude.

How big a cavity is 10 million litres? Could you perhaps sample this big a volume using the interior of the balloon?
10 million litres is 10,000 cubic metres
4/3 pi (r)cubed
So 30000 = 4 pi (rA)cubed
So 7500 = pi (r)cubed
So 24000 = (r)cubed
So the cube root or 24000 = r in metres
This is a radius of about 29m
So, a balloon 58m across has a volume of 10 million litres
Is this too big? How much does the canopy weigh? I have no idea.
One could in theory fly the canopy with helium to altitude, then rapidly deflate it and fill it with ambient air. If it was fully sealed, the canopy would then rapidly descend and collapse upon itself since the exterior air would be getting much denser. You would be left with a crumpled canopy with a volume, at ground level, of about 100,000l - a precious sample of high-altitude air of a sufficient amount to possibly replicate the U2 experiments.

Please feel free to pick this apart/add references! I can just about believe the U2 results from this (so much air sampled along the transect) but now have doubts about any bioprospecting results claimed from high altitude balloons so far, unless they drifted for long distances (1000s km) before recovery. Both of these types of experiments involved culturing on the ground, so as always ground contamination, or contamination of the balloon before flight or by aerophiles in the troposphere, remains a possibility.
Our efforts to carry out experiments at altitude negate this BUT how do we sample enough air? Must we fly on a long duration balloon now?
One cfu literally means one single bacterium landed on the detector and was able to divide and grow into a visible colony. In turn this would literally mean only single copies of key genes to be detected by us by RT-PCR etc. In short, it doesn't matter how sensitive your assay is if the odd bacteria you are chasing in millions of litres doesn't happen upon your detector - otherwise there is nothing to detect!

Long duration? MAIDs? (Microfluidic?) Collapsed canopies? Any thoughts gratefully received!

Ol
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'Wild' micro-organisms

At the end of October, I went out to a secluded area of campus and sampled the micro-organisms in the air on settle plates (agar plates) for 5min. I used two types of plates, just plain LB agar and this with some magnets in, as I was interested to see if the magnets would have any affect on the growing bugs. (Later I may use the magnets to hold down the plates.) I used 4 plates per experiment but exposed them all at the same time, then incubated them at 4, 24 or 37°C. After 24h nothing had happened but after 48h small fluffy white colonies were found on the 24°C plate, then after 2weeks colonies were found on both the 4 and 24°C plates but not on the 37°C plates. At the time of sampling I also used the homemade impinger and will use the DNA in this for detection in the RPA reaction. I can now use this reaction to amplify sequences from DNA derived from archaea and yeasts too.

Pscyhrophines, hypobariophiles and radiophile

In researching how we’re going to detect microbes in the stratosphere I have been looking into what they might have to deal with – the cold (psychrophiles), low pressure (hypobariophiles) and radiation (radiophiles). There’s quite a bit of research out there reporting on psychrophiles – many organisms are surviving in the ice in the Arctic and the Antarctic, from bacteria or fungi. A whole conference has been held on them! There’re also reports on radiophiles, such as Deinococcus radiodurans, which is being exploited by NASA. But of hypobariophiles there is little (actually none that I can find) information of their existence. We should also think that these organisms will be xerophiles, meaning they can tolerate and grow in low water conditions, these can also be halophiles eg the fungus Trichosporonoides nigrescen, or endoliths, that live inside rocks, which would help with radiation protection too. The latter tend to be autotrophs too, making essential chemicals by themselves. Some many requirements......can there be such an organism?

Recombinase Polymerase Amplification

Just a quick update to say that the first run of the recombinase polymerase amplification (RPA) has been successful. This is a great technique, that is over shadowed by the popular PCR reaction, that amplifies DNA sequences, the massive advantage here is that no specialist cyclers are required and it may even work at below room temperature....lots of things to try! For more info try the Twist DX website.

NURBS rubber duck!

Not to be outdone.... I have successfully created a fully NURBS rubber duck floating on a funky textured ocean, being regarded by a giant floating eyeball.

Seriously though... this is my first Rhino structure - a powerful 3D design and imaging suite.

http://www.rhino3d.com/

I have now completed preliminary training and can proceed to designing the High Altitude Bioprospector as a 3D model - which we can then actually produce as finished parts using a 3D Printer.

In many ways this might actually be simpler than that duck - all straight edges! It took bloody ages to get those eyes right and even then it has a rather menacing myopia to it...

Set up 1

I had a mini glass impinger made by the glass blower at the university and then bought myself a small battery driven fish tank pump. With a few modifications to the pump I now have a system for pulling air through the impinger, perhaps a little wildly, but its a start.