Found Jonathan Loer from Freetronics. Hey, and he's got the Um Aru board. The satellite board Yeah, this is the payload processor module, which is one of the parts of Rat 1 and Rat X. Those are two satellites that are currently at the International Space Station and they're just about to be deployed into orbit and this is the board that will run experiments.

Each one of these little rectangles is a complete microcontroller with all the supporting parts, and so each one of these is essentially equivalent to an Arduino Uno. In fact, it's running the Arduino bootloader and this chip up here is a supervisor processor which talks to each of them through multiplexes. So as far as they are concerned, they're an Arduino plugged into a computer and the supervisor can load new sketches onto them and each one of these has access to all of the sensors on the satellite. And Um, there's also some storage and various other things on here, and the idea is that each of these runs totally independently so you can have 16 experiments running simultaneous L and they don't need to have any knowledge of each other.

And um, the idea with that is that we can amortize the cost of the satellite across a whole lot of different people. Mhm and I've got a few other boards here as well. so just as an example, this is a little test stack that I've been playing around with on my bench and this is representative of about the size of the total of the final satellite. It's a 10 cm Cube You can see in the middle there is the payload processor module.

It's another one of these. There are currently five of these boards in existing. Two are here, two are in orbit right now and another one is over in California at the ground station. Um, This on the top is a prototype of a satellite power supply module.

So it's got um. input from solar cells so it can charge. It's got a management processor so that it can do things like measure current consumption and battery state. and um, so it's got a couple of high current switch mode power supplies on here which Supply power to the rest of the satellite through the bus.

The satellite has has a stacking bus that you can see there. So basically the idea is that it's like a stack of pancakes. So the satellite itself is just a series of modules that you build up and they all sit on the same stacking bus. and how do you keep it warm cuz it's in space.

Yeah, well. The interesting thing is that um, keeping it warm is not is not really so much a matter of space being cold. It's more a matter of how do you control the heat. Um, on.

There are really three ways that temperature can be transferred between different part of a system and um, there is no convection because there's no air obviously. but you still have radiation. So if you have hot spots, you can radiate heat. Uh, basically the thermal profile of the satellite.

Once it's in orbit, it orbits about every 92 minutes and it goes from about- 40 to about plus 80 over that cycle. So basically the board is slammed down to -40 and then it's up to plus 80 every hour and a half. So it goes through some pretty s. It's still within within a designable range.

Exactly. Yeah, it's not ridiculous. So the problem is that when it's on the dark side of the earth, so when it's in Shadow it'll be radiating heat. and then once it comes into sunlight, it starts absorbing heat.

and it's just a matter of managing that. EXC The major problem is batteries because we all know batteries don't like getting cold. So what a lot of satellites do is have heating coils under the batteries. So when they're in the on the dark side, they Heat up and they keep the batteries warm.

And what's the Uplink to this thing? How do you? How does it communicate back to Um: there is a radio module I don't have on this particular stack, but the satellite itself uses 2 M 70 CM Amer um transceiver modules in it. So in fact all of that information is published. so if you got the right gear, you can listen in on the Telemetry. It's not encrypted or anything.

and how do they deploy it? Do they just toss it out the window? almost? Um, they are deployed using a device called a PE pod which which stands for Poly Pico satellite orbital deployer and it's basically a big box with a spring in it and a door on the front. So what they do is the um. the cube sets go inside the PE pod which is mounted on a slid on the end of a robotic arm on the space station. So they basically point the arm in the right direction and then release the door and the spring pushes them out, pushes it out.

Yeah, that's it. That's it. Awesome. So the space station itself is traveling at about 28,000 km hour in it orbit.

So they um, they take G the same velocity basically as the space station right and and then decays over about 6 months or so. 6 months. Okay, they've got no propulsion so they can't actually change their orbit. but they have orientation control using things um called magnet torquers which is basically three big coils so they react against the Earth's magnetic field.

So essentially it just because there's noic. there's no friction so all you do is energize the coil and you can. Yeah, it's one of those things when you hear about it's like obvious I wouldn't have thought of it exactly. But yeah with Magnor cuz you can get about plus orus 5 pointing accuracy.

Wow and um there you could do that for any mass in theory. Yeah yeah, that's right, but they don't do that on spacecraft do they? No, that's that is done on satellites. Other wayse it's done with um Reaction Wheel So basically mot with a mass on it, youin the wheel and thenc rotes here I Was thinking that they all use Hydr you know, fuel for the for the orientation. No.

but one of the limitations with Cube Sets is for safety reasons. They don't like you're sending up any kind anything that could be explosive or dangerous in any way. So they have to go up totally inert so they're not allowed to be powered up until they after they have been deployed. All right.

Interesting. Does that only apply to cube? Sets Only applies to the little players. Or do the big players get a free pass? Probably. It really depends on how the deployment is happening.

So the thing is that cubesats are pretty much second class citizens when it comes to space. Tech So they're hitching a ride with other missions. If you're the primary Mission then you can specify what you want and and it's done to see your requirements. There are some Cuets now that are experimenting with active propulsion systems as well, and people can upload their own sketches to this and another can.

That's right. Fantastic. There's a sket in Space. Yeah.

so there's a software tool that, um, it runs in your browser. So it's an IDE in the browser. and you can plug your own Ueno into your laptop. test that your experiment works, and then there's a little drop down and and basically it says deploy to you can deploy to your Uino or deploy to satellite.

It sends it via the Internet to the ground station and it's then Uplink to the satellite. Uh, and then it's loaded onto one of these long processes and executed, then the results sent back to you. Did anyone think about putting a camera on it so that you can see real time that your lead's blinking? No. Um, there are cameras on the satellite, but they're not pointing at the board, not pointing back at itself.

Excellent. Thanks! John Hope it works so it's being deployed in the next. Well, we don't exactly know it's in the work CU for the astronauts. Once they get around to it, the way it works is there's no specific schedule.

They have a list of things to do. They get through a certain number each day, so sometime in the next month or two, they'll be deployed. Fantastic. All right.

good luck. Thanks.