We've got Caston again from the Google Lunar scientists. Yes, yes. and we're going to talk about space electronics and what makes it hard? What makes it hard? Yeah Electronics in space it's not just launched and I mean the vibration of the rocket and everything else. Now we're not talking about that.

Yeah so this is actually the easy part I Guess yeah right. launching it and later in it and all that. Yes I was. When you're talking about electronics in space, it's not like the ship knows oh no I'm in space I mean no I would break.

You know this is not the point. The thing is that when you're going into space you are. you're leaving the the atmosphere which which is providing you with sufficient shielding from the radiation environment that there's a Sun and what types against radiation are they? So there are so depends on where you are. So if you're for example if you are a CubeSat fan and you know that there is a low Earth orbit which is about 300 to 800 kilometers and in that you you have the inner build of the Van Allen belt in it.

Yeah so the inner blood is dominated by protons so they you know they make all kind of crazy stuff. for example so that if you if you think about space there are two things that you have to take care of. It's A it's called the total dose and it's called the single event effects. Yep the total dose is is something that types of radiation we're talking Yeah exactly Yeah, um it's a you can think of it's a gradual effect.

So you have your N PN junctions. Yep, and there are ions coming in and they are manipulating the doting of the after though. they're interacting with the doping of the yes, silicon. Exactly and right.

And this leads for example, to the effect that that your transistors don't switch as fast anymore. That Okay, so it starts to degrade the transistors performance. Yes, all right, it's a saw. That's all gradually, right and how gradually we're talking about? Oh well.

um, can it be destroyed in days depending on the feature size? Well yeah, it depends on it, depends on actually the protection that you have. So if you have absolutely zero protection right? Um, sorry, there was no. So if you've got your Arduino board just flapping around in the breeze in space, um that's interesting. I would have to check on how quickly that would be dead.

But um, the good thing about the total does is that you can add shielding right? So what you're doing is usually you you add some aluminum where if you want to go fancy you get some to tell them how thick does it have to be? So this is the this is the question. how thick has to be to survive your mission And there's a personal mission so you can calculate all this. Yeah and that have obviously determined. Oh I need an inch worth because I'm going into deep space for ten months? I Need Yeah, exactly so.

But the thing is that um, an inch for example, doesn't doesn't do much more than a half inch. Got it? So it's the you know, first tenth of a millimeter that helps you a lot. Yep, and you know millimeters. Quite good.

The mini Sheen returns yeah and one senator is if you want to go really fancy you know so and so it depends on what your what your mission duration is like. So it's also if you want to make a five-year orbit and Leo then you can expect about 20 kilowatt which is the Rhine for measuring that deposit dose and the silicon. And then you can. then you need to figure out what what shielding you need to add to get down to the point where you wouldn't want to decide on the limit of that.

Oh Abby Yeah well no order magnitude under is there a rule of thumb Sir, that's a good question you you've what you're much depends on what your margin policies. You know if you the thing I said if you want to, um you can you can be very safe and very very expensive. Yep all you can be cheap and do lots of stuff so you can be Voyager 1 and 2 Cost is no object. A polar cost is no object.

you know. let's just do it right. Every liable yeah you can go are no worry, she'll be right. Yeah I think so.

for example this is a the policy that we are for example adapting that you say we want to do as many missions as possible and so for example cubes that they think the price is about ten thousand dollars per one day unit. Yep yeah and so you can say okay we'll know whether I will fly ten and there is a chance that after our three years half of them are dead. Yep and this would be very valid. You know they can be perfectly yeah because if you if you if you try to add a shielding your mass increases and your size increases and and the longer I keep set exactly And yeah so this is this is a philosophy that you did you have to you know think about what your what your aim for, the mission is and the total dose is actually the part where it's quite easy because you just you just add your you're shielding depending on how much total dose your device can stand.

So now is this something you get in the data shape? well more than the regulars are. but you can ask them for aerospace-grade Yeah far you know space great For example day they if you want to hotel if something is the space great they have to do some radiation testing and already the total dose Yeah there. but there are also many you know many people around the bowl that do some to testing. So it's for example.

It's quite easy to get together me Cobalt-60 right so you can put on it and then you get a very very of how how well it goes and but you can also do use a proper radiation source and do some total dose testing for the mission duration that you're aiming it and the and their the shielding to provide the links. So how do they radiation harden the chip? You buy the normal version in your by a radiation hardened version. What's the difference? Paperwork: So then the paperwork? Is that it? No, that's not. That's intuitive.

We don't tasted it. if they're like. it's a bit of a simplification, but the thing is that there's nothing physically different. It depends sometimes of us, sometimes it's not right, sometimes.

um, well obviously they've tested them and they've sorted out that maybe this one is a good what. They can't test it cuz it's fatal dose. Yeah so but thank you. What you do is you take on a one, take one waiver on behalf of them, and then you know your heart.

Very generous. Okay, you bombard them. Yeah, you take like like a significant symbol size like five to seven for example and you then you do some radiation testing with it and then you have a very rough idea of what the status of the other ones is and then you know if you're talking about a proper space. great stuff.

Then you also do a magic sealing packaging you know which I of course all the fancy stuff. you had some shielding and do all the fancy bits and then you know you have a chip that will definitely work a radiation environment up to the total dose at your supply. but also it depends on the on the process that that something is manufactured in. So some also gonna say feature size makes a huge difference if you're working in fewer than leading-edge FPGA it's twenty nanometers or something.

This is This is where it gets very interesting. Yeah the future size does not make a huge - it doesn't make a huge difference No so but for example, what was it's so but if you mentioned doping before yeah it comes in the process technology not just features. Yes yes But the song is that the if you want to for example build it a smaller process then you need to have a tighter control over all parameters and so you know this can disconnect it. And for example if you look at some of the single event effects which we'll come to in a second you see that and in a smaller process does not lead to a higher single event upset right? which means bit flipped essentially.

But let your s chain coming back to the total dose. Yeah so um this is um this is for example influenced by how thick your layers are. Also if you are talking about you know film fed technology you know it's A The transistors are made entirely different then and if you have a bipolar process yeah if you are very Moloch same if you have Park Siemens if it's silicon on insulator, this all comes into play into what your total doses and sometimes sometimes it's really just that one batch is bad. Where is another one could be pretty good.

We've got the Total Dose which can slowly kill your chip. Yeah, what would you shoot against? Which is which can shield against in which ways there's so you can. you know airfoil you can. Oh you mean Iam? Is there any other materials that work better? Tantalum was one of you preferred one.

So using tantalum type which is its antenna? no it. uh German accent uh I would have to look it up. What's called Okay alright there is a material there's there's yeah that's so it's a computer use in the composition with aluminum and so you have a little lay of the other with the I one. Okay so this can help you up to a certain thickness you get because you get diminishing with you can returns on the thickness.

Yep okay so you can do some shielding with that now I Just one more thing on the total dose. The datasheet says it'll survive up to this dose. What does that mean? It'll still function to all the specs up to that dose. Yeah, this came.

it's not guaranteed. Yeah, but you don't know what specs will fail d exactly. You just it. it's to don't go there.

Yeah, it's lost your fingers And this is for example one of the why some of these space great stuff is is lower weighted and frequency for example then than the regular commercial pot. Alright single day single event single. Oh yeah so there is a whole group of what's called single event effects. and where do they? Where's where's the source for the total dose radiations? This you know what sort of space radiation is it? Where is it coming from? So this, uh those are the the low energy electrons mostly and so they the cosmic rays.

No cosmic rays are coming from outside the solar system as I which will be a solar Sun Yeah radiation from the Sun like a right. Essentially you've got and is that for both the for the dose and for the single event assault radiation. Yeah so the the the so it depends on what you're talking about. very right.

So so you have to the Sun which provides you with plenty of protons and some ions yep and then gets trapped in the melon bed and then you get some some electrons which are trapped there and is suited. Yeah particles flown around and if you're flying in that all through it then your then you have to deal with it Yes there's also an interesting spot on earth which is called the Southland Economy which if you fly through there is a connection of what protons I guess um interesting. So it's a in the most east of South America Very interesting. There you go.

So you don't live there? Yeah yeah yeah so we don't We don't attempt to fly through that. Ok excellent Anyway right So the single so single event effects are as a group of of effects that you can have with with high-energy particles. So the Grinnell we're talking about cosmic rays. When people think of your space rated they probably think of cosmic rays.

Oh and my phone just stopped working. Must be a cosmic ray bit flip you know? Yeah, kinda. What about the actually Sun produces some high energy particles as well? Okay right there's there's a good source as well. so you have to low energy particles with Joey for the total dose and only high energy particles.

It's the energy difference which differentiates two types. Got and the single event effects are you have the single event ledge up which is that? Yep so CR match up Yeah yes yeah let's up will typically destroy a chip it once on how quickly you're able to do to switch it off or it's just which are okay Yeah so you have the you have th up if you so which can destroy you the transistor for example if you are not switching it off quickly enough and you're not, you need to switch it off and remove the energy as well. Yes, so not just switch it off but really put it to Crohn's sub speak And which is why filtering on your power supply can be bad because it's got a lot of energy in the bypassing and it can keep dumping energy. And if you're out switched off my power supply no you haven't Oh, you're bypassing is still supplying a big gulp of energy Destroy your transistor.

Yeah, exactly Yeah yeah. And so this is a bit as one source. and the the interesting thing about the single event that job is that if you are, if your process for example allows for a lower voltage, you're less expectable to. So single village up you're less susceptible.

Yes, I would have thought lower voltage would be worse. No, it's not. No, it's not. Yeah Interesting.

And so some of the newer processes are less expected to single urban letters than the previous ones because I'm near one point one volts or point eight volts core voltage or something stood and silicon on insulators are for example also very immune to that. Yeah, so this is a very very rough thing right? So can cause latch up. what's the next problem? Yeah it's a sleepy yeah but flipping is sort of. It's called bit.

flipping is called single event upset. There are soft and hot single event upsets so the soft one is you have you have a memory cell and instead of a one you're reading a reserve or the other way around and if you're right over it and it's it's Rebecca to normal and the hot single event does have upset is you cannot write to it for you know it's like for its time right? Sometimes are the Neil's okay? Yes so the effigy. but dealing with the soft single event upsets. This is where where stuff gets really interesting because this is what everyone is afraid of in it.

Everyone's afraid you've got this big die which is your Ddr3 memory or whatever it is and it's good. It's a massive die. big square area because it's a random event, bigger the square area of the die the more changing. Exactly right.

And because it's big memory, are you something's gonna get hit? Yeah, how do you deal with it? Yeah. so this is where where you start to choose some of the processes for example that have ECC to Reactionary Duck which is that you read and correct it. Um you can. What if the error correcting circuitry gets hit You screwed? Yeah yeah.

well space the time. yeah. but the thing is that it's a small area you know to see. the memory is fine.

Yeah but Murphy will get you every time. Yeah the thing is but about single area upset is that you can. You know you can deal with it and by by having error Corrections or by having TMR which means the tend to be modular redundancy. For example if you have a in a processor you have register, you have ten three registers and then you do majority voting exactly and take this one and um this is all yet are you doing any of that in he um so we.

This is why for example of using lose a Spot fusion tube which is the pros is actually having a dock for the the memory interface. oh it does. It's going to build in I said its features there yeah every night in the FPGA area as has some ECC going on. Um so this is your 30 some some error correction and the thing is that with PhD I can do some testing about the radiation effects of the IP course that we're developing and so we can take an air care of that.

The thing is that you have a big area and was for example many registers and you have to know which bit is actually important. You know not all bits are created. You know that's right, someone more important. Yeah yeah some of them are junk.

Yeah so you don't care about if they are flipped exactly and so you have to. You have to know which which of the bits are for example in the control path which are in the data path. You know in the data you know it doesn't matter if there is a instead of 127 your encoding age 108 in there in an image. you know no one notice.

Yeah! but in a control pass you know it makes a difference between turning left and turning right. Yep, so you need to. You need to make a decision on which parts you want to TMR To make them redundant against a single event upsets which parts you can just ignore. For example, dosage in single event.

Is there anything else? Yes, you have to from a single event. You also have the single event transient which is when you are having a spike in the past. for example, just you. There's not much you can do right? right? Yeah, So you could have to deal with the Dom that on the team are level for example.

And and you've got some software. The European Space Agency Oh yeah. so there's some software. Oh yes.

Oh yeah. so this is these sort of stuff. Yeah so if you want to there is a software called spend this which is the space environment. blah blah blah.

Can anyone download this? This is a website. Really? just like a you just go there. You can register thank you you enter you are your orbit and then you can take a look and see what you get out of it right? Can you can calculate for example the singer than upset right? Interesting and it'll give your recommendations for different materials for thickness. No, no, you do that yourself, your honor.

I can. Got it. So what are you most concerned about passing through the Van Allen belt? Yeah, The Vanilla Buggy. Yeah, is that How big is that? How long do you spend in the Van Allen belt? Not long.

So this is a good news. Yeah, Oh, by the way, from from a total dose per perspective, yeah, there's also some annealing effects. so once you accumulated some, you know when you're passing through even I'll But for example, you accumulated cemetary some dosage and some of it will anneal depending on the temperature and the biasing you're doing. Interest, weather, and also the total dose that gets deposited also depends on whether the the chip for example was was biased.

So ever. if you are running some application is a high frequency, a chance to accumulate more dosage than the dispenser switch off. Interesting pesky physic, pesky silicon, physics and all that rubbish quantum stuff. Yeah, yeah, so yeah.

so you know the quintessence of it is that you have to decide on on how much failure your your four exam will accept. And one of the things that you need to know about Miss Parents for example, is the most of the models that are dealing with the solar particles, for example, are made for solar flares. That doesn't. So it means that essentially on a good day you could have no trouble at all.

Exactly. So Flay comes up. You're screwed. Yeah, because you don't want to design? Yeah, that's won't be one of your risk factors, right? You go.

well. we have a 1 in 50 chance of a solar flare. We're not gonna add 20 kilos weight exactly, but if I did meet for example that maybe your requirement if you're flying a mission today. That's course.

When two years exactly, you know the chances of having a solar flare. I Guarantee ya, that's right. Yeah, But if for example, following mission duration right? Um, you know we are not expecting any many solar flares and this is some of the trade off. We have tied it earlier on that.

We are designing as good as we can. but if you have a solar flare we are and we know that so what? You wouldn't be much cooler over through the valley alone Ellen belt would you? Because I assume it's just powered down. Yeah and it be it wouldn't be doing anything so you get to get some dosage. but you're gonna survive that right? that? that's always a given.

You can always guarantee you that. Yeah. But so yeah, if you, it depends on when you pass route. you know.

so it depends as disciplines on your trajectory. Oh yes, it was. Yes, Because you don't. People think you just shoot straight off earth like that you did yellow straight up.

No Yuge. Yeah. So so for example, one of the early trajectories we had was, you know, localizing about five times five orbits? Yeah, if I forwards and um, and then they were a translunar injection as a hint. Yep, I know you know you're a lie.

You know you're will try my very much. Is it a three-part system? Because you got the rover? Mmm. you've got the lander. Yeah, but you've got the ship that takes it there or is the lander? The lander is the ship rights that the lander is the spacecraft that takes up.

there. Is that all we need to know about surviving space? Well yeah. If you so if you want to live I've space you for example, it's it's good Way to start with chipset stuff and oh yeah, go on from that. So radiation is much bigger problem.

The thermal. Yeah. The thing I said you know is with Soma, it's quite easy. You know how much what ship dissipates and you need to get rid of it? Yep.

but what you really can't tell is how much dosage is ship mascara is. Be able to handle without you're making Rawley agent s. But that's why you buy space grade and that's what you're paying for. Yes, oh yeah, there is.

So yeah, maybe it's being tested and you've got some data. You know you know how bad it is. Yeah, it doesn't. You know space graders so you can buy.

There's a difference between radiation hot and radiation tolerance by the way. Oh yes there is radiation Toyland is ours is usually designed for you know, lower dosage right? And so far CubeSat stuffing right? Cheapest stuff. Yeah and Radiation art is really for deep space missions that are gear geostationary satellites which lasts for any many years 10, 20 years or something like that. Yeah, but usually so it's a occasionally it's It's a bit of a rip off because you you just get the same ship.

Is that? Yeah exactly. They with a different test report. yeah we're with different test report who knows. so that's Pruitt you.