On Earth testing of the moss

[deljr15]

It has been brought up a few times that tests need to be done with the moss.

What will be required for this test to begin?

[MBobrik]

Funny, I wrote a post morning, but there is no trace of it here. So here we go again.
What is needed ? The moss itself. Identical growth medium to the one we will be using. A completely dark place with controlled temperature and humidity. Means to measure its O2 consumption and CO2 release. Which means either keeping it in a very tight sealed volume and having CO2 and O2 sensors to measure it, or measuring it indirectly by growth medium weight and carbon content decrease and plant weight increase. Which involves either capability do measure very small weight changes, or a sufficiently large amount of grown moss.

[Newt]

Vernier has CO2/O2 sensors available. But the two of those would cost us a fair bit of money. How precise of changes in these gasses do we want to measure?

I personally would suggest that we try to make the sensors as close as possible to the actual sensors that will be used in flight. However it might be nice to include more sensors on the ground so we can make better inferences about what is going on on orbit, which could include a large range of tests, which may be connected to the measurements we will receive from CO2/O2 sensors et cetera.

For the most basic run, MBobrik's list covers all the necessities as far as I can see.

[deljr15]

On the topic of measuring equipment I would lean more toward a member that has a biology lab setup, or at least knows someone with the stuff.

The moss its self and possibly testing rig (dark box) should be the only things we need to buy for the test.

Another thought. After we get a hold of a sample would it be possible to breed it to give a "unlimited" sample supply?

[Newt]

(12-23-2014 09:47 AM)deljr15 Wrote:  Another thought. After we get a hold of a sample would it be possible to breed it to give a "unlimited" sample supply?

I fail to see a reason that we could not. However, this raises the question of how we will actually build the satellite in the end, shipping the sat and the moss and the radio internationally several times will raise a hefty bill. But I digress. We could probably ship pre-dessicated moss to the person building the rest of the sat, especially if we are doing nothing with the moss afterward but packing and launching it.

[deljr15]

(12-23-2014 09:55 AM)Newt Wrote:  However, this raises the question of how we will actually build the satellite in the end, with shipping the sat and the moss and the radio internationally several times will raise a hefty bill.

Well this is a topic for its own thread. I have been thinking on that one as well. Basically each part will be individually build tested and shipped from country of origin. Final assembly will be done by someone located reasonably close to the launch.

Of course this means that the first time all systems come together will be before launch. Which means we will need a final testing procedure for person in question.

Sub assemblies may also be possible, however I believe this to be a topic for after we have a good collection of systems.

[MBobrik]

(12-23-2014 09:35 AM)Newt Wrote:  Vernier has CO2/O2 sensors available. But the two of those would cost us a fair bit of money. How precise of changes in these gasses do we want to measure?

I personally would suggest that we try to make the sensors as close as possible to the actual sensors that will be used in flight. However it might be nice to include more sensors on the ground so we can make better inferences about what is going on on orbit, which could include a large range of tests, which may be connected to the measurements we will receive from CO2/O2 sensors et cetera.

For the most basic run, MBobrik's list covers all the necessities as far as I can see.

The problem is, I couldn't google any detailed information about oxygen consumption of the moss. Only very basic information like that it grows to a 10 mm diameter colony in 25 days. We don't thus know how small we have to make the enclosing space so that the changes in concentrations are measurable, and whether sensors we can afford can work with that small volumes.
So, as the very first run, just to acquire the first useable numbers, I would suggest we go with the grow a lot of it and measure growth medium mass loss and plant mass gain method.
Either that, or some biologist who has access to existing data pops in and tells us the numbers. ( Mazon Del ? How's prof Luis ? :-) )

[MBobrik]

One thought @ testing. Since no one of us got good means of either measuring CO2/O2 concentrations, nor scales precise enough, nor an easy way of extracting the constituents back from the growth medium to measure how much of each other got lost, the best way how to estimate the air volume needed is a direct experiment. simply taking a number test tubes each filled with the same amount of growth media, and varying amount of inert stuff like sand on the bottom, so that the size of the air pockets inside varies. Glue the openings with microscope glass, and let them grow in a dark damp box. Then observe the growth and note the day where it stopped growing or started significantly lagging behind one which got an open lid.

[HenryRasia]

@MBobrik, yeah, probably having standard test tubes, moss, and equipment would be more efficient than trying to replicate the exact orbital experiment on the ground*.

*though we'll still have to run the *exact* same experiment sometime before launch, that's for sure.

To further support this argument, we shouldn't be afraid of running tests, failing, not being precise enough, and having to do it over. An experiment on the ground will always be orders of magnitude cheaper than the one in space. That being said I dint think we should all run and buy a biology lab kit just for initial testing. Anyone with a camera, some dirt, some moss, and a small plate can gather information that, though limited, will be invaluable this early in the design process. I'd just say to anyone who can get a friend/professor/acquaintance who's into college biology to get an experiment running. It's going to be small anyways so it wouldn't take away the institution's resources or anything. I know some people here are in college, would it be too much to walk up to the biology department, knock on some doors, and ask around?

[NERVAfan]

(12-27-2014 10:39 AM)HenryRasia Wrote:  To further support this argument, we shouldn't be afraid of running tests, failing, not being precise enough, and having to do it over. An experiment on the ground will always be orders of magnitude cheaper than the one in space. That being said I dint think we should all run and buy a biology lab kit just for initial testing. Anyone with a camera, some dirt, some moss, and a small plate can gather information that, though limited, will be invaluable this early in the design process.

OK, I think I will try this out.

But have we even made a final decision of what moss species to use? I remember Mazon Del listed 3 different possibilities back on the KSP Forums thread.