[Music]

[Screen reads 'STEM Education']

Presenter

Most people have some idea of what a satellite is. We generally think of big spacecraft orbiting the Earth, playing some crucial role in communications, weather forecasting, or making our GPS work.

But what if I told you there are satellites small enough to fit in the palm of your hand? They're called CubeSats, but what could they be used for?

CubeSat satellites are as small as a 10-cm cube that are mainly launched into low earth orbit to observe the earth test new communications technology or perform space science experiments.

Why were CubeSats created when we already had bigger, larger satellites? CubeSats are a class of satellite that were created with the intent of making space science accessible to education.

Unlike large, traditional satellites, which are expensive to build and launch, CubeSats are small and low-cost.

Why are they important? CubeSats have led to broader access and participation in space exploration, providing hands-on educational opportunities and enabling innovative exploratory space research.

ProtoSat is a shortened name for prototype satellite. And it comes from the idea that teachers and students will use an engineering design process to design, test, and evaluate a prototype CubeSat capable of collecting weather data.

Students learn about some of the key development stages that space scientists and engineers undertake to design and test their CubeSats and apply those processes to develop their own prototype.

While actual CubeSats get launched into low earth orbit, our ProtoSats remain on earth to collect weather data.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

Today, access to weather data is as close as the weather app on your phone, but what does that temperature readout really mean? Is that the temperature right here, right now, where we are?

A couple of questions to think about.

How different is the app temperature reading from the temperature measured with a thermometer? And how different is it from the temperature measured with the digital sensor?

If we get different measurements with different devices and sensors, which measurement is the correct one?

Teacher 1

These two temperature sensors here are giving us the reading that's localized at this classroom environment, so indoors specific to this room.

Whereas the app here is getting all the data from the different satellites and kind of, weather monitoring stations that are all outside.

So this is giving us kind of a general kind of snapshot of the outdoor temperature compared to the indoor one that we've got here from these two.

Presenter

Students use different devices and sensors to collect temperature and humidity measurements to compare with a range of sources like the Bureau of Meteorology and other weather apps, and consider reasons for any discrepancies.

One other thing to note here is that, because we are not actually sending ProtoSats up into low earth orbit, we will base our designs on a system that measures terrestrial weather on Earth as opposed to space weather.

That means we can consider things like humidity, which might not be as relevant in space. Alternatively, measuring the amount of ultraviolet light could provide some other interesting opportunities to collect data.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

The code for collecting weather data from a sensor will depend on several things.

One, the platform being used, for example, the microcontroller and the language used to program it.

Two, the sensor used, or if there are multiple sensors used.

Three, the frequency that measurements are taken.

And four where and how we record the data.

Student 1

This is the early stages of the coding. We're using a temperature sensor to record data.

Here we have a temperature sensor, a raspberry pi pico, and a power timer.

As you can see, the code is coming up.

[Student 1 shows his laptop, which displays the code.]

Presenter

The data can be easily saved in any plain text file format, but thinking forward to later parts of the unit where the data is organized and presented in graphs, it'll be handy to save it as a CSV file.

If students want to compare where the data from multiple ProtoSats, it will be easier to combine and analyse it if it has been saved in a common format.

Establishing some consistent standards early on will save time later.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

FlatSat is a shortened name for FlatSatellite.

It is an assembly of the different electronics and digital technologies the spacecraft requires to function and complete its mission.

Lay it out on a workbench or on a platform. It is connected just like it will be in the satellite casing.

FlatSats are extremely useful for testing electrical and software interfaces between different subsystems.

This allows engineers to perform integration testing before the planned operational satellite is even manufactured.

The purpose of the FlatSat is to ensure the components and the code work together as planned before installing them into the proto set.

Student 1

I'm in the early stages of coding, so obviously we've got the Pico here.

Connected to the expansion board, which is recording the temperature through there that's connected to it. As you can see, we've got the temperatures recording here.

Student 2

We're in the final stages of testing. We're using a battery pack and a power timer that we set to 6 seconds to record quick ratings.

Presenter

A flat set could be set up and left operating throughout the unit to collect weather data as a reference data set for later comparison.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

After students have confirmed the FlatSat components work together and the code is correctly collecting weather data, the next step is to design the structural frame of the ProtoSat and work out how all those same components are going to be placed inside the casing.

The design must still allow the components to function correctly like they do on the FlatSat. In other words, the ProtoSat design needs to produce comparable temperature readings to that of the FlatSat.

Using the engineering design process, we can follow some familiar steps. One, define the problem to be solved. Two, identify any constraints. Three, brainstorm possible solutions.

And then after investigating some of these options and refining our ideas further, the design will be based on the most promising solution.

When defining the problem, it helps to map out initial thoughts and consider additional questions like, how often will the ProtoSat collect temperature measurements? How are the components securely mounted to ensure they don't move around? How long will the power supply need to last?

Some constraints relevant to the ProtoSat design are:

• each of the sides are 100mm long
• there is a mass limit; the total mass of the ProtoSat needs to be under a set value, for example, 200g
• available materials and tools.

And this can have a significant influence on the design.

Just a quick mention now about the influence of materials and tools on design options. As an example, laser cutting acrylic or plywood will be relatively quicker to produce, but the design may be constrained by parts that are flat sheets. The design then needs to take into account how various sheets are attached together.

On the other hand, 3D-printing components will present another set of design challenges.

As we progress through the ideation process, producing thumbnail sketches and annotated drawings of initial ideas can help generate more ideas to support the brainstorming process.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

Hi, thanks for joining in. In this tutorial, we are looking at 2 types of drawings that you can use during your design process or at the end to present your amazing work. To help you with your ProtoSat project, let's draw an actual CubeSat to help develop the skills that you can use in your designing.

[Screen shows diagrams of a CubeSat.]

On the right is an isometric drawing. It looks like a picture or 3D. On the left, we are looking at what some people call plans. It's a set of orthogonals or looking directly onto the face kind of views. You can choose to follow along with me today if you like.

You may be comfortable drawing freehand, but if you have an isometric drawing tool or a set square, grab that now and let's get started.

[Screen shows two human hands using a Splat 3D tool and a pencil to draw.]

Pick a starting point and draw an isometric cube. The Splat 3D tool has 3 steps to draw a cube. This is the second step, rotate upside down, line up the corner, and there's my cube. Great.

Let's draw a sensor. How about a camera that's pointed down towards the earth? Great.

Now we're going to need an aerial to upload information and download. Some CubeSats, actually use, uh, just a basic kind of measuring tape and it pops out or deploys after it's launched into orbit.

We've got a solar, uh, solar panel on one side. I can round the corners off and I'm thinking about some screws that might hold the cover on some extra little design detail in here.

Now I'm using a dark line right around the outside to help the drawing stand out on the page. On this type of view, we can also record measurements or dimensions. The line should be fairly thin, and all of the measurements are usually in millimeters.

Now for the orthogonals, choose the most important view and call that your front view. If I looked at it directly on it would look something like that.

[Screen shows the words “front view” and an arrow pointing to the front part of the CubeSat diagram.]

So let's draw that one over here to scale. I'm using half scale or scale one to 2. So I'm drawing that knot at a 100mm rather at 50mm. So I'm sketching a square, and inside that I'm putting all of the detail that I would see on the front view. Remember, these are quick design drawings.

Let's think about the top view. From the top, I would see a square with an aerial, but which way would the aerial be facing? Well, let's think about it. If I was standing right in front of the cube and I lent over and looked down, which way would the aerial be? If you said across ways, spot on.

So now I will firm in the outside of the cube and add my design detail. Cool. We'll label those now. Top view and front view.

Here's what we'd see looking at the left side of the cube. But where on our page, on our orthogonals would we draw it? Here's how to figure it out. Think about the front view as your home base.

There it is. We go up and draw the top. Back to the front view, come out and draw the left-hand side.

Here's another way to think about it. Imagine that front view is a cube sitting on a table. If I move my head around to the left side and look, that's what I draw in that position. Let's go back to the front.

Now, imagine walking around to the right side. That's what I draw in that position. And from the front view, if I lean over the top, that's why I drew the top view in that position. In Australia, that's the way engineers and designers always set out their orthogonal drawings. It's called the third angle, and it has a symbol. It's like a cone viewed from the front and from the side. Look for it on some plans.

The word isometric means that both of these edges are angled up by the same amount, and that is 30 degrees. Normally we wouldn't color in orthogonal plans, but if you did want to present them and make them look more like solid objects.

Here's a really quick way. Use some Post-it notes as a mask. Rub a cotton wool ball onto some chalk or some soft pastel.

Now start off your drawing. It's really important. It's my top tip. Start off the drawing and then work across. You want to try and fade from dark to lighter. I try not to put too much on. A little bit, as you see, goes a long way.

Now I'm cleaning up my lines a little, sharpening them up and using a circle guide. I'm doing the same on the front view, but to make it look like a shiny metal, I'm using an eraser to cut a few reflections through it, a wide and a narrow.

Here's a simple way we can use the same method to render our isometric cube. Add a little bit of color to the far corner. Notice the front corner is still white paper. Let's put dark next to light. That's contrast. It makes our drawings look really interesting. And then the far corner. Add a little bit of dark and fade, just a hint of color in that far corner.

Cool. You can use that over and over again. Use an eraser to clean up.

Some low cost CubeSats actually use measuring tape as an aerial because it rolls up and then springs out once it's in space.

Here's a tip when presenting your final drawings, not only go around the outside, but vary the weight from thick to thin. It makes your drawings look really interesting to the eye.

Today we've looked at two really important ways of sketching your ideas when designing: an isometric view, 3D and orthogonal views for drawing plans.

Thanks so much for joining in. I'll see you in the next tutorial where we look at two more ways of drawing and that is an exploded view and a sectioned or cut through view.

See you soon. Bye.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

Hi, and welcome back to Part B. In this tutorial, we are looking at two more types of drawings that you can use during the design process to draw and design all of your cool ideas. So we are looking at an exploded view on the right, which is an isometric drawing with the sides taken off to show all of the parts inside and how they fit together.

It's a very powerful type of drawing, especially if you are intending to show the drawing to people who may not normally be able to read plans or orthogonal views.

So exploded views are very common. On the left is a front section. A sectional view is the type of orthogonal, so we are looking directly onto the front or side or top, but we're cutting through with an imaginary blade so that we can see how some of the parts fit together.

Very good, very, extremely technical people that really want to know all of the detail. You may want to follow along and practice drawing with me in however you are most comfortable, whether freehand or with the aid of a set square or a 3D isometric drawing tool.

Let's create a very simple design, something that could be constructed outside of a workshop.

[On screen are two hands with a pencil, ruler and piece of white paper.]

I am beginning as I did in part one with an isometric cube. And I'm adding a base, which could be cardboard, sheet timber or acrylic. Let's shade one side with lines to help imagine it as 3D. Now, this is an ellipse. I'm drilling a hole into each corner. Now I'm going to mirror that at the top of the cube.

Let's join those together with what could be plastic rod, threaded rod, or even some wooden dowel. I suggest do your whole drawing using very light lines and only darkening when you're finished. That way you won't need to erase. I wonder what you would use in your design to hold the top and the bottom together.

Here's how to draw a few options. Example, the threaded rod, or maybe even some 3D printed square shape or section. I'm going with a simple wooden dowel. Now it's time to explode the top. So, imagine taking the cover and sliding it up in the air and redrawing it in that position. Let's add some thickness, the far corners, and there's our cover.

Let's erase a few of those lines we don't need. Here's some small holes in the top for some screws. I am using a guideline to make sure that the screw lines up with a hole and that's going to go into the top of those rods.

These dotted lines help imagine how the parts all line up. Here's a great tip when erasing, use a scrap piece of paper as a shield to cover your work.

Place a mark halfway up the dowel or rod. I'm drawing in a small platform that I can use to mount some more electronics on. Give it a little bit of thickness.

Draw in the far edges. Now where the dowel goes through, let's add half an ellipse. You may choose to erase and do a little fix up where the rod goes through the board or the platform.

[On screen, two hands hold a box with circuits affixed to it.]

This is a breadboard. It's used when prototyping circuits. Grab a scrap of paper and let's draw one of those. Start by drawing two isometric lines.

Here's a big tip, rather than any old angle to join the ends, use a vertical line. Great. Now from three points, draw an isometric line out to the right. At the end, another vertical line and an isometric out to the left. Great. So, it's easy. It's just like a cube, only lower. You can add your design detail if you want to.

Let's draw a breadboard onto our ProtoSat, the two isometric lines, the verticals, the three lines that go out to the right.

A vertical and just a short left. Let's try drawing a microprocessor. Notice this one has a square data port and a power port.

[Screen shows a finished exploded diagram.]

You can see the Arduino here, I've colored blue.

Same as before, let's draw two lines only closer together. Here's our three right hand side isometric lines, but this time I'm extending them to make the board look a little bit longer.

Next, I'm drawing the headers. This is where the wires would all connect into. There's some on both sides of the board. The data socket is really just a small cube, and the power socket is a cylinder. Watch, as I draw the Arduino Uno onto the platform.

How will you hold the Arduino down to the platform? Will you use screws or plastic bolts or even double-sided sticky tape?

This platform is getting its own dark line or cutting line around the outside to make it easier to understand the drawing. Notice this one goes thick to thin to make it look a bit more visually interesting. Here's the power pack with a switch and the lead begin with the two isometric lines than the verticals.

We're drawing the right-hand cover exploded away as well with the splat in the original position. Imagine sliding in the isometric direction and drawing the cover. Draw in some thickness and then design a way to attach your cover to the ProtoSat.

Let's explode the left side, cover off. With the splat in the original position, slide in the isometric direction, draw the cover, and then add some thickness.

I am using an ellipse to draw a hole in the cover so that the power lead can go through into the port. And for the data cable, I'm going to draw a square hole. For this design to work as a weather station, we're also going to need to think of a way to allow air to easily flow through.

The second type of drawing that I really wanted to show you today is called a sectional view. We'll be drawing it at full scale, so it will be 100 by 100 mm.

Let's start off lightly by drawing a box. Inside the box, I'm drawing two more lines to represent the base and the cover. The thickness depends on the material that you've chosen.

Let's join those together. I chose to use some wooden dowl. Here I'm extending the dowel into the base. So, I drill a hole and then I'd be gluing that in there. For this design, I'd like the top cover to be removable. So, I'm holding that on using a screw and that's how the screw would look if it were a front view.

A sectional view, on the other hand, allows us to imagine the material cutaway to see them actually connected together. Next, I'm drawing the platform halfway up, and on top of that will be the Arduino. On a sectional drawing, I can imagine taking the cut wherever I choose. So, imagine I'm cutting right through the dowel.

Quickly recapping: So far, we're drawing a front sectional view. We drew a box, then we designed a base, and here it is drawn on our front sectional view. We drilled some holes so that we would be able to glue in some rods or dowels. Here's a common error where the platform meets the dowel. If I'm cutting through right there, then I really should see the dowel go through the platform. Let's just fix that up.

So, I'm putting a hole in the platform and now it's more like a sectional drawing. Currently with our design, the platform is free to move up or down. We're going to need to fix that somehow. And I don't want to glue it because I'd like to be able to adjust it. Trying to keep our design really simple, what about we look for some rubber tube or even elastic bands to stop that platform from moving?

Here's how it could look on the isometric drawing. Remember where our section line is? We're cutting through that position, and I show that with the dot dashed line and some arrows with an A and an A, so I'm cutting between the As. That's why this drawing is called a Section AA.

Remember, on a sectional view, we are cutting away material to see what's inside. Here's the cutting plane. Notice, I've drawn crosshatching or slopy lines to show where it's been cut. This is a different component, so we're using a different angle of hatching.

I've chosen not to cut through the board, the platform, or the microprocessor, nor my screws and holes and things like that. In the first video I showed a really simple way with Post-it notes to rub on some pastel or chalk to make these drawings look a lot more. 3D. This is called rendering, using light and dark to suggest a form, but it can also give a hint at what type of material it's made from.

It is great to annotate straight onto your exploded drawings, so show all the components and features with arrows and labels. On the other hand, orthogonal drawings like this section drawing are a little more formal, so we'll use letters to identify the parts and then we'll put the explanation inside a table.

Congratulations, you now have four types of drawings that you can mix and match during your design process. Give these drawings some practice. Even if your first drawings are a little rough, your teacher will love that you've given it a go. So good luck. Thanks for joining in. I'm Glenny D. Bye for now.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

The next step in refining the design before creating functional prototypes is to transform the sketches and ideas into CAD drawings. Okay. We can then use the CAD drawings to produce high fidelity prototypes using rapid prototyping tools like 3D printing or laser cutting.

Teacher

[Teacher and student sit in front of a computer screen displaying drawings on the CAD program.]

Now, at the moment you can see that that's colored red. Yeah, and the reason why we color it red is because red for us, and our software means it's a cut line. Oh, so a laser will read the red colour and it knows it needs to go full power, really slow to cut away through the material. Right.

Presenter

The building of prototypes will be dependent on cost, time, available materials and tools.

The main rapid prototyping technologies available within schools would be 3D printing, laser cutting and CNC machining.

Each of these fabrication techniques will have their own design considerations. For example, 3D printed parts are stronger in the direction, perpendicular to the layers. For parts, carrying loads, this can be an important consideration.

Laser cutting will be relatively quicker to produce. But a unique aspect of using laser cutting for prototyping is the fact that laser cutters can only work with sheets of material.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

After functional prototypes have been designed and assembled, we need to test the prototype design for structural integrity. We also need to test that the components remain securely attached to the ProtoSat body and that they correctly function in a range of conditions approximating a typical space flight.

This is sometimes referred to as the Environmental Qualification Campaign, and engineers do this testing so they can fix any potential problems before the CubeSat is launched into space. CubeSat engineers also call this the ‘Shake and bake’ stage. We'll look at the ‘Shake and bake’ as two separate processes.

The ‘shake’ part generally refers to a vibration test, and it is used to simulate launch conditions and other parts of the cube sets flight, which experience varying levels of vibration. Students research how vibration tests are carried out and how they can design and construct equipment and jigs to safely carry out a vibration test.

The aim is to confirm that the frame design maintains its structural integrity, and the components will remain securely attached to the ProtoSat mount points in a range of flight conditions.

Now the ‘bake’ part of the phrase refers to a thermal test. The thermal test is used to simulate thermal conditions in space, which could be extremes of hot or cold temperatures.

To safely conduct actual thermal cycling and thermal vacuum testing requires highly specialized equipment, so the safety advice is to only consider investigating the effect of low temperatures on the operation of digital components. Students can research how thermal tests are carried out and how they can safely design and conduct investigations to carry out a thermal test based on cold temperatures.

This could be as simple as investigating whether the ProtoSat continues to operate when safely placed in a fridge. Other inquiry tasks could explore power supply performance and endurance, material testing and shock or impact testing.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

It is likely most groups will only have time to focus on one design issue in the student-led inquiry. So, it's a good idea to encourage students to present their findings and share data, which could also have implications for other groups and their prototype design.

With this broader collection of findings, students can discuss within their team and decide what further modifications may need to be made and present these for teacher approval.

Teacher

Alright. So what, what was your solution? Talk me through it.

Student

Just use a zip tie to attach [using] one of these holes and then you can get fresh air as well.

Teacher

Okay, fantastic. And you've tested it.

Student

Yep.

Teacher

Alright, so we give it a bit of shake. It’s not moving.

Student

Mm-hmm.

Teacher

OK, awesome. That's what we want. So that idea, to put that zip tie there

Student

Yep.

Teacher

Completely solved your problem.

Student

Mm-hmm.

Presenter

With approval, students can perform any necessary modifications to improve the structural integrity or performance of the ProtoSat, and then assemble hardware components ready for deployment.

Before a CubeSat is considered ready for launch, a flight acceptance review report is submitted.

This documents for the customer, what requirements and deliverables have been achieved and the results of various tests conducted. This is critical for compliance and accountability in the space industry.

Each student group produces a flight acceptance review report to demonstrate the processes undertaken and the readiness of their ProtoSat to be deployed.

NASA has a term for deciding when a space mission is to take off or to abandon or postpone the launch. This is called the ‘Go/No-Go decision’, and it happens on launch day. To build on the CubeSat mission context at the start of the unit and align with industry processes, the teacher can set a launch date, which the class can then work towards with incremental checkpoints and deliverables.

After confirming the ProtoSat has been tested to ensure it will function correctly and cleared for launch, it can be deployed to a safe location to start collecting weather data.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

After the ProtoSat has been deployed to collect weather data for a period of time, it can be recovered and the data retrieved from storage.

Depending on the components used in the ProtoSat design, this storage could be internal flash memory or on an external storage device like a microSD card.

If the data is stored on internal flash memory, it can be downloaded from the microcontroller to a computer via a USB connection.

The default ProtoSat components are capable of measuring temperature, humidity and atmospheric pressure, including a time value that is four data values for each recording event.

The number of decimal points can also be specified for each data type as it is written to storage.

Extra decimal points in values are not likely to cause data storage concerns, but the point is, do we need to record temperature to four or five decimal points, and how accurate is that representation anyway?

Unless the ProtoSat has been programmed to record weather data more than once every 10 minutes, the data set is unlikely to take up a lot of space in storage.

Ultimately, the amount of data that could be saved will depend on the frequency of data readings and/or the size of the available storage.

[End of transcript]

[Music]

[Screen reads 'STEM Education']

Presenter

Preparing and organising data will be a lot easier if the ProtoSat code has been written to save data in a standard file format like CSV. This will also make it a lot easier to import into a spreadsheet program.

If this was overlooked earlier, it is still possible to use the data to create graphs, but more effort is going to be required to arrange it into columns and rows, and then make sure the correct time and temperature values are aligned.

Creating graphs, using spreadsheet software, is quite straightforward after the data is imported. Just keep in mind that spreadsheets use the word chart instead of graph.

The next step is deciding which type of graph is most suitable for the purposes that we need. Line graphs are commonly used for communicating continuous quantitative data that changes over time, and they can be very helpful visualizing trends.

So, line graphs are probably the best option for our ProtoSat weather data, unless of course you have a different purpose.

Student 1

So the benefit of us turning this data into a graph is it's much easier for us to visualise and see it this way rather than in lots of scaled numbers down. And you can quite clearly see how the data changes throughout the time.

Presenter

Other purposes could include making comparisons between data sets or identifying relationships when you want to express the correlation or connections between various values.

Somewhere in this process, we also need to consider and assess the quality of the data.

It is important to recognise if there are any anomalies or outliers within the collected data and question where these may have come from and how to deal with them.

Random or missing values can have a huge impact when creating line graphs.

After analyzing the collected weather data, what's left to do is to evaluate the results and consider these questions:

• Which weather data is more accurate: the thermometer, the weather app or the ProtoSat?
• What is the value of weather data?
• What is the value of CubeSats in space science?

I hope you enjoy the ProtoSat unit and encourage you to imagine the future possibilities with these new skills and knowledge.

[End of transcript]