Month: February 2014
If you follow us on Facebook, you may have noticed we had some problems with the vacuum chamber yesterday. Oh, this vacuum chamber…
Summarizing, to create vacuum, we need a pump to suck the air which is inside, what’s obvious. However, since we want a steady environment in the chamber, and only gravity interacting with the particles, the pump cannot stay turned on all the time, otherwise its counterflow will interact with the tests, making them less reliable.
This is why the system works in stages: the pump is kept working for some minutes and then a valve blocks its connection to the chamber. We have our steady state! =)
However, we missed a detail yesterday, a very small detail: After the tests were done, to open the valve it’s necessary to open the equalizer nozzle, from where all the air will pass to refill the chamber.
We missed this detail.
The vacuum sucked something else in instead of air.
It was oil. A lot of oil!
Ok, but as it said around: “shit happens” and we needed to be quick to solve this issue, since other teams also use the vacuum chamber for their experiments. Having oil in it could affect their measurements and the vacuum quality.
At this time, two brave members volunteered for this task. And after hours of dangerous and hard work, smelling acetone and dealing with really expensive components, one of them pronounced!
– I really enjoyed this job. It reminded me about my old days playing with Lego.
What can be seen next is an resume of their work.
And a thing must be said. It can seem trivial, but vacuum science is a whole world of techniques of assembling, cleaning, sealing and so on. There are books and books about it!
And of course, we need to know what we are doing!
More dedicated than ever to push science forwards and make it understandable for everbody, the team has decided to go to the next level regarding the advertisement of the SCRAP experiment. Our goal is ambitious: within one year, everyone in the street should be able to give an educated answer to the question that will be entertaining us today.
“If you pick up dust from under your bed and sprinkle it in space, what happens?”
A recent unbiased survey conducted in utter agreement with scientific ethics on a very representative sample of people randomly chosen in a bar after midnight draws rather dim conclusions on the general awareness about dust in the mesosphere. Typical answers include
– It’ll glow green, right?
– There is no dust under my bed, I am a very clean person, by the way I am searching for an appartment…
– Put that microphone away from my face!
This question is in fact very serious and central to the SCRAP project. Of course, there is no way to know for sure before the experiment is done, but one of our key objectives at the moment is to predict how the dust cloud will look like on our measurements.
Since we are dealing with radar scattering, what we are looking for is the spectral signature of the microparticles. That is, we want to identify specific features in the radar signal which would tell us that our dust is there and give us information about its size and electric charge. With the help of plasma theory, it is possible to describe how the wave amplitude and frequency are modified by the presence of particles. Then, the big issue is to know whether we are able to measure these modifications…
And that’s where optimization comes into play! Though there are many constraints we need to fulfill – strangely enough, they wouldn’t let us release 15 tons of mercury droplets in the atmosphere – we still have some room to design the experiment. All the parameters we can act on (particle size, amount, material, …) are still being investigated in order to maximize our chances to have a beautiful radar signal in the end.
Sooo, the bachelor students are planning and spreading out their work load over the spring. We are officially not allowed to spend more than 400 hours on this project during this semester. To make this reasonable believable, each one of us is making a state of the art project plan. This includes Gantt Charts, Risk Analysis and a WBS (Work Breakdown Structure).
There are many different software’s to choose from, when doing these planning documents. I will here give you an example of how a WBS, made in LaTeX, may look like:
You could also do some minor adjustments to give the reader a picture of which parts of the project take more time:
Ok, LaTeX is for free, which is a really good advantage. But as a student at KTH, you can get your own copy of almost any work environment. I don’t believe that you would come even close to the same amount of time aligning pictures, even in Microsoft Word. In LaTeX, putting your pictures in boxes on minipage’s in table’s is the easy way. Well, enough ranting.
I will use LaTeX tomorrow, and the day after. LaTeX wins.
/The SCRAP team
SCRAP is an experiment that involves a semi-hazardous particle powder to be dispersed, either by explosives or by being sprayed mixed in a flammable liquid using highly pressurized gas, from massive containers ejected from a rocket launched 80 km up into the atmosphere. The powder is then to be observed by a radar located 200 km away in a different country north of the Arctic Circle. Now this is not only a very difficult challenge, as mentioned in previous posts, but apparently also a pretty risky business. In fact, there are a great number of things that can go awry, involving not only the safety of our personnel and the success of our experiment, but also that of other people and experiments. During the last few weeks, we have been attempting to identify the main perils, their likelihood and severance as well as how they may be prevented.
To start with, there are a number of risks involved with our ejection system. This uses a pyrotechnical device to cut wires and a number of strong springs, which could be very dangerous if handled incorrectly and must work in practice. Luckily, the ISAAC team has already done much work on this, which will be a great help in our pursuit of functionality and safety. Several other components could also malfunction during the rocket flight, such as the electronics, batteries or the structure of our entire rocket module. Most of these possible issues are, however, well understood and should be controllable with a few tests in an environment of similarly extreme temperatures, vibrations and vacuum.
Once our ejected units have performed their tasks, parachutes must be deployed, so that the data that has (hopefully) been recorded by the spectrograph and camera on board is not destroyed in the landing. This will require tests involving a car driving at high speed to see that the parachute deploys as expected and fulfills all demands in braking the speed, as well as actual drop tests. When the ejected units have hit the ground, it will of course also be necessary that they can actually be located, for which our localization system will be very important and must be tested for all possible scenarios.
The radar must be operated in a safe way, so that signals are never transmitted directly at the rocket or in any other way interfere with the experiments on board. To learn how this can be done, and hopefully gain much other useful knowledge, we will be sending a team to the radar facilities in Tromsø in the end of March (expect more news about this in the future). In order to actually be able to detect anything of use, we will of course also rely on a suitable distribution of injected particles and sufficiently agreeable plasma conditions.
A powder of particles with a few micrometer radius can be very dangerous if inhaled and can in some cases also be flammable or even explosive. Furthermore, for certain materials and large quantities, such a powder could also have a negative impact on the environment. For copper particles, which is currently our main candidate, these effects are relatively minor for the quantities we will be using. We will, however, still have to analyze how the experiment could affect our surroundings and always treat this powder with utmost care.
For the spray approach of particle injection we have been considering, there are two main safety risks: the pressurized gas that must be used and the flammable liquids the particles are to be mixed in. For the explosives approach, the major risk is the gunpowder that is to be ignited. Just as with the particle powder, these substances will require strict safety procedures to minimize the risk of accidents. For the flight itself, we will be relying on a solid design and risk analyses to ensure that nothing unforeseen can occur and that we get a sufficient spread of particles.
Last, but not least, there are also some risks in the project management that could be fatal to the experiment. If, for example, we find some critical errors too late in the testing phase to fix before launch, the entire experiment will suffer, but this can hopefully be avoided by managing deadlines appropriately. We must also be prepared for unexpected changes in personnel by always documenting the work that has been done, so that no important knowledge is ever lost.
/The SCRAP team
Image Posted on Updated on
What would Valentine’s day be without SCRAP? ❤ We think not complete! Therefore we finished a school presentation this morning for our supervisors to present at the House of Science this afternoon and obtained the first results of our testing…
As mentioned earlier, we are studying three different release methods to form a cloud of copper particles: a spray approach with a basic spray set up (nozzle, atomiser, liquid) where we mix the copper particles with aceton, we are also testing a method which we call the “fire extinguisher” where we simply will spray out the particles using a similar approach as a real fire extinguisher and in the third and last method we are using gun powder to spread out the particles.
Today we received some first results (!!), this from the first testing of the gun powder approach: we obtained electron microscope pictures of the copper sample used in the testing, see above for one of these pictures. The hearts were quite unexpected yet It is very exiting to start seeing results of the ideas we have discussed and worked on for quite some time now. This week the fire extinguisher set up is being tested, it was built by Simon before he left and hopefully soon we will also test the last, yet first mentioned, spray approach! We are just waiting for the atomiser to arrive.
Its very exiting to see the results of these methods soon coming up, which method will be chose? Time will soon tell!
The most crucial part of the electronics in the SCRAP experiment is the computer the will carry out the experiment. This computer allows us to carry out the experiment in a controlled manner. The computer used is a Field Programmable Gate Array of FPGA for short. Even tough you probable never heard of this type of computer, chances are that you have one in you pocket right now. They exist in everything from avionics to surgical systems. There also exist similar computer systems which does not require as much effort to use. These are known as microprocessors and can be compared to the CPU of your desktop. Whith these computers you can do all kind of crazy stuff. Here is a link to cool things you can do with a microprocessors.
So if you have alot of empty beer cans, why not make a new keyboard out of them? or build your own quadrocopter, or find a cheap way to stream video from your computer to your tv? Computers are just magic dont you think?
/The SCRAP Team