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Now Ye're Talking - to the team for Ireland's first satellite, EIRSAT-1
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04-10-2017 8:20am#1We're very excited to have this AMA to celebrate Space Week!
Students, academics and industry mentors at University College Dublin (UCD) and Queen’s University Belfast (QUB) are currently designing Ireland’s very first satellite, EIRSAT-1. The Educational Irish Research Satellite 1 was chosen as part of the Fly Your Satellite! program in May 2017 as one of 6 student led teams to take part in the program. This satellite is a 2U CubeSat, which is a type of small research satellite.
EIRSAT-1 will carry two experiments demonstrating innovative Irish technology.
The first payload is called GMOD, the Gamma-ray Module. This is a Gamma-Ray detector, and it will be used to detect Gamma-Ray Bursts, the most energetic explosions in the Universe.
The second EIRSAT-1 payload is EMOD, the ENBIO Module. This experiment tests thermal coatings developed by Irish company ENBIO Ltd., for use on future missions.
As a student-led mission, UCD and QUB space science and engineering students have the opportunity to develop sought-after skills in the Irish space industry. The team have to meet strict review deadlines and milestones in order to progress in the Fly Your Satellite! program. They are currently in the Critical Design Review phase and are working hard to ensure that the mission gets accepted for launch from the International Space Station in the coming years, subject to strict reviews from ESA experts.
Lána Salmon is a PhD student in the UCD Space Science Group and Outreach manager for EIRSAT-1 and Lána will be the opne answering your questions here this week.
You can follow their journey on their website www.eirsat1.wordpress.com and Twitter @EIRSAT1.
Let's blast off with some great questions! (Sorry
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Haughey Was Framed wrote: »Sounds amazing! So many questions!
How long will the satellite be in orbit for?
How is it powered?
You mentioned it's being launched from the ISS - how does that work? Is someone throwing it out a window?
Good questions!
The satellite will be in orbit for about a year. We've done simulations that vary from about 9 months to possibly up to 2 years. Why so uncertain? At the relatively low altitude of 400km, there's still enough atmosphere to cause a significant aerodynamic drag which slows the spacecraft down and eventually causes it to de-orbit. The amount of drag is dependent on solar activity amongst other things so it can be difficult to say for sure. We make a best estimate based on the past solar activity during a similar phase in the solar cycle.
The satellite will be powered by solar panels. It will have solar panels covering the 4 larger sides. It's a lot easier on such a small satellite to have panels that sometimes face away from the Sun than it is to include the necessary systems to make sure the panels point straight at the Sun. The satellite will also have a battery so it can remain fully operational when it is eclipsed by the Earth.
The launch from the ISS is about as close as you can get to throwing it out the window in space. It will be loaded into a CubeSat deployer with a number of other satellites. The deployer is basically a tube with a big spring at the bottom and a remote controlled lid. So it's kind of like a Jack-in-the-box or even a Pez dispenser. The Japanese module on the ISS (Kibo) has a small airlock for experiments. The deployer will be taken outside through the Kibo airlock and a robotic arm will pick it up and point it away from the station and then the lid will open and all the satellites will be "launched". We need to include some very small springs in the end of EIRSAT-1 to push it away from the other satellites that it will be launched with.
Thanks!0 -
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How much will the project cost and where do you get funding for something like this?
How many points did you get in your leaving?
Do you like watching sci-fi movies/programmes?
If yes, which is your favourite? Also, do you shout at the telly when they suggest doing something you know is not physically possible?
Good luck to you and your team, hope it’s a great success!!! 0 -
Thanks so much!Gloomtastic! wrote: »How much will the project cost and where do you get funding for something like this?
Hi there!
We estimate the cost of the mission to be about €1.5M over 3 years - this will be spent on supporting studentships, internships and of course materials and much more.
How many points did you get in your leaving?
The EIRSAT-1 team members have achieved a wide range of points in the Leaving Cert. Here are two team members backgrounds:
David Murphy, System Engineer -455, but that was before bonus maths points.
Lána: I got 560 points in 2013 - lucky enough to get into the UCD Science undergraduate course! Whilst most people think that you need to be a genius to be in astrophysics, I think our team represents a wide range of abilities and we all work to our own strengths.
Do you like watching sci-fi movies/programmes?
Yes, we love Sci-fi - doesn't everyone? The EIRSAT-1 team are serious sci-fi movie/programme fans.
If yes, which is your favourite?
David Murphy: Wow, that is very difficult to answer! There’s so many good ones! I’m just going to have to post a list of some of the ones that I love. 2001: A Space Odyssey, Moon, Gattaca, The Fifth Element, Sunshine, Blade Runner, The Martian, Interstellar. I could go on for a lot longer. On TV, I really enjoyed The Expanse, though it’s not as good as the books. I appreciate how they always go to a good effort to get the physics right.
Lána Salmon: I'll have to agree with David, and add the new Star Trek movies! Although it's not really sci-fi, BBC documentaries like Wonders of the Solar System were my gateway into physics.
Also, do you shout at the telly when they suggest doing something you know is not physically possible?
David Murphy: Yep, I’m very guilty of this. Though I have learned lately to try and leave it go, you can enjoy it a lot more that way. Sometimes they have to introduce one big inaccurate concept to make the story work - that’s what makes it fiction, right? But it still really annoys me when there was an easy way to get the science right without effecting the story.
Lána : I think physicists/engineers love talking about whether what happens in a movie/tv programme is physically possible. Don't get us started about Interstellar!
Good luck to you and your team, hope it’s a great success!!!-1 -
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frozenfrozen wrote: »any pictures of renders or anything so far so we can see what it looks like?
We don't have any photo-realistic renders yet, but hopefully this gives you some idea. To give you a sense of scale, it's 22.7cm tall! The antennae that you see sticking out at the bottom will be stowed for launch and we'll deploy them 30 mins after leaving the space station.
frozenfrozen wrote: »how are you going to be communicating with it, is it 1 way or 2 way communication and what kind of security is there for accessing the information gathered by the satellite? Is there a constant stream of data or is a period of time sent in bursts?
We're hoping to communicate using amateur radio. We don't have a frequency allocation yet, but the Irish Radio Transmitters Society and the International Amateur Radio Union as well as ComReg have been very helpful to us so far. It's two-way, we'll use 9600bps downlink on UHF and 1200bps uplink on VHF. That's not a very fast connection! And to make matters worse, it will only be in range of our ground-station at UCD for an average of 6.5 minutes per day! So we have think really hard about what data we want to get down to the ground. In terms of security, it's not allowed to encrypt broadcasts on the amateur band except for satellite control commands. So all the data coming down will be wide open for anyone with the equipment to listen and we definitely encourage that! But we can prevent other people from controlling the spacecraft.frozenfrozen wrote: »How much power does it consume, and is it powered by solar panels or a nuclear battery? and do you have any way of moving it in case it was going to crash into something else?
It has a bunch of solar panels that you can see as the blue sections on the picture. You wouldn't believe the hoops that need to be jumped through to certify a lithium battery as safe enough to be allowed onto the space station, so anything nuclear would be right out! The spacecraft runs off 2 watts on average, more when we're transmitting but we spend most of the time not transmitting. Because of power conversion efficiencies and the time we spend in the Earth's shadow, we need to be generating an average of 3.7 watts when we're in sunlight.
We have attitude control but no orbital control. So we can control where it points but not where it goes. So basically, we can't prevent it from hitting anything, but that's really unlikely anyway.frozenfrozen wrote: »how many years will it stay up there and is there any way to get rid of it when you are done with it?
About a year. See the response to 'Haughey Was Framed' above for why we say about.frozenfrozen wrote: »sorry for all the questions feel free to give short answers or skip any of them so you don't have to spend ages answering just me
No problem! We're very happy to talk about all things EIRSAT-1! Thanks!0 -
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EIRSAT-1 Team wrote: »[...]No problem! We're very happy to talk about all things EIRSAT-1! Thanks!
Great answers thank you 0 -
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Great thread and great project! Lots of questions...
Is attitude control just to keep the sat from spinning endlessly or it is required to point the instruments in particular directions?
Is it a gyro within?
Can we get a bit of technical detail on the internals, such as the computers controlling the Sat? Are they linux based etc. Does they have to be hardened/shielded for cosmic rays/ solar flares etc? Or have you stuck a few Raspberry Pis together in a box ?
How did you go about designing the Sat? Have you had a few prototypes built already? How do you test for how it will perform in Zero-G and a vacuum?
What is the most difficult aspect of the design/build (I imagine weight) ? What is the design brief/specifications that you have to meet? Weight, performance etc...
Nate0 -
Nate--IRL-- wrote: »Great thread and great project! Lots of questions...
Is attitude control just to keep the sat from spinning endlessly or it is required to point the instruments in particular directions?
Is it a gyro within?
We're actually going to spin the spacecraft around the long axis on purpose to help stabilise it, but you're right in that what we're trying to avoid is 'tumbling' where the spin is a bit unpredictable.
It's a bit of a balancing act to keep the different subsystems happy in terms of where the spacecraft should point. The Gamma-ray module (GMOD) is at +Z end of the spacecraft (the top in the picture I posted a while ago). That makes this end of the spacecraft the most sensitive to gamma-rays. It can also detect gamma-rays that come through the other end, it's just not as sensitive because some of them get absorbed. Since the gamma-rays (at least the ones we're most interested in) come from space, it makes sense to have the top pointed away from Earth at all times. We call that zenith pointing.
The Enbio module (EMOD) wants to heat up samples using the Sun to see how hot they get and how fast they cool when we go into the Earth's shadow. So for EMOD pointing directly at the Sun is best. But there's a problem there, if we point the top at the Sun, the solar panels which are on the side never see the Sun. It turns out that a good compromise between both EMOD and the solar panels getting the Sun they want is to do zenith pointing and that's great for GMOD. So that's what we're trying to do with the attitude control.
We debated using gyros, but in the end we kept coming back to our first idea which is magnetorquers. These are basically electromagnets and when they're energised they can provide a torque against the Earth's magnetic field causing the spacecraft to rotate.Nate--IRL-- wrote: »Can we get a bit of technical detail on the internals, such as the computers controlling the Sat? Are they linux based etc. Does they have to be hardened/shielded for cosmic rays/ solar flares etc? Or have you stuck a few Raspberry Pis together in a box ?
Sure!
We're building a lot of the stuff ourselves - all the electronics and detector assemblies for GMOD and EMOD, the antennae and its deployment system, the structure and all the activation and separation stuff that goes along with that. But we are buying some of the systems off the shelf, such as the Onboard Computer (OBC).
The OBC is supplied by a Scottish company called Clyde Space who specialise in CubeSats. It uses a MicroSemi Smart Fusion 2 System on Chip (SoC). The SoC provides a real CPU and an FPGA which is also used to synthesise another CPU, but the main purpose of the FPGA fabric is to synthesise all the various different hardware interfaces we need. Those are nothing exotic, they're what you might find on a Raspberry Pi (i2c, SPI, TTL UART, etc.), we just need a lot of them. The Smart Fusion 2 was chosen because it's fairly radiation tolerant. It's also got magnetoresistive RAM which is non-volatile and radiation immune, Error Detecting and Correcting storage and other stuff like a hardware watchdog. So basically, a lot of protections against radiation.
We did explore rolling our own using a Raspberry Pi compute module with a radiation-hardened micro-controller to act as a controller/bootloader. But the Clyde Space OBC seemed like the safer option for our first satellite.
The OBC will run a RealTime Operating System. I think it has a custom kernel, so technically not Linux, but not entirely different.Nate--IRL-- wrote: »How did you go about designing the Sat? Have you had a few prototypes built already? How do you test for how it will perform in Zero-G and a vacuum?
We knew it would have to be a CubeSat to stand any chance of us being able to procure a launch for it.
We basically started by asking ourselves "Okay, so what's it going to do?" The obvious thing to us, since we've been working on new types of gamma-ray detectors for ESA for a few years now, is that it should detect gamma-rays. Specifically, it should detect Gamma-Ray Bursts (GRBs) since that's a topic that we're really interested in as astrophysicists. Then we tried to figure out how small we could make our gamma-ray detector based on the previous prototype detectors that we'd built and some new technology that we knew was coming down the line.
CubeSats come in a fixed number of configurations - usually 1U, 1.5U, 2U, 3U, 6U and sometimes bigger, where a U is the base unit which has a size of 10cm x 10cm x 11.35cm and a mass of 1.33kg. Our detector takes up about half a U in volume so a 2U CubeSat made sense once we factored in the other systems that would have to be onboard.
We also approached Enbio about turning their thermal management coatings into a student experiment since we have a good relationship with them and we thought it could be done without taking up too much space on the satellite.
That's basically how we arrived at the general idea and the basic design. After that it was a lot of iterating over a whole bunch of different requirements and tradeoffs, and seeing what systems were available to us.
As you've probably guessed, we can't really test in zero-g. For tests of the attitude control, we can place the spacecraft on very low-friction bearings and make sure that the spacecraft can turn. Unfortunately that's only one axis at a time, but it's enough to make sure that the actuators work. Vacuum is a lot easier, and we won't just test vacuum, we'll also test temperature extremes. That's done using a thermal-vac chamber that can expose the spacecraft to vacuum and heat it up or cool it down. We'll test going from hot to cold to hot to cold very quickly to make sure EIRSAT-1 can withstand it. We'll also shake the crap out of it to simulate launch and make sure it doesn't fall apart.Nate--IRL-- wrote: »What is the most difficult aspect of the design/build (I imagine weight) ? What is the design brief/specifications that you have to meet? Weight, performance etc...
Nate
The main design brief/specification that we have to conform to is the CubeSat Design Specification published by California Polytechnic. ESA have actually given us a custom specification, but I can't share that and it doesn't diverge too much from the one I linked. Weight turned out to not be too much of a problem. The CubeSat spec is well thought out so when you design something to fit in say 2U like EIRSAT-1, it ends up being around about the correct weight. So we didn't struggle with that at all.
The most difficult aspect was trying to balance attitude control, power generation, and mission lifetime. We wanted good attitude control because we wanted to be able to accurately point the spacecraft to make it the most sensitive to gamma-rays and to accurately know where EMOD was facing and how much solar energy it was receiving. That implies we should use reaction wheels (gyros) which are better than magnetorquers, but reaction wheels are very power hungry, we'd need maybe an additional 3 watts of power. We couldn't generate enough power for the spacecraft using the solar panels we had so we'd have to add more and they'd have to be deployable because there was no space left on the surface of the spacecraft. Deployables are risky so you always want to avoid them if possible and they increase the surface area of the spacecraft which increases drag which causes de-orbit to happen much sooner, completely killing your mission lifetime.
In the end it took a lot of going back to the drawing board, running a lot of simulations, and getting some good numbers on what sort of performance hits the instruments could take (by not having the absolute optimal attitude) in order to end up with a feasible mission.
Thanks for the questions!
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Since this is Ireland's first satellite, I think we'll make our own traditions!Haughey Was Framed wrote: »Are there any traditions or customs you'll follow when you're launching your satellite?
Yes! Ideas welcome!Haughey Was Framed wrote: »Will you invent one of your own?0 -
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On Friday, 4 October 1957, the Soviets had orbited the world's first artificial satellite. Anyone who doubted its existence could walk into the backyard just after sunset and see it. — Mike Gray, Angle of Attack
I saw Sputnik, or my father or uncle told me that was what we saw.
How many satellites have been launched since then?
That's an interesting question! What counts as a satellite? Does the Space Shuttle count even though it's the same object that's been put into orbit multiple times? That's probably open for debate!
The best answer I could probably give you is the number of International Designators that have been assigned by COSPAR, the Committee on Space Research. COSPAR do count each Shuttle launch as a separate satellite. To date, they've assigned 7821 designators to spacecraft. And the first one is 1957-001B for Sputnik.
In case you're wondering, 1957-001A would be the rocket that put Sputnik into orbit, but rockets aren't included in the 7821 spacecraft, so we're just counting the satellites themselves (even though rockets can spend a long time orbiting the Earth after their job is done and by some definitions would count as a satellite).How many circuits will the Irish satellite do, how many days/years will it be orbiting?
EIRSAT-1 will be launched from the ISS and so it will have very similar orbital properties as the ISS. That means we'll get 16 orbits per day. Assuming we stay in orbit for a year, that's 5840 orbits, or over 250 million kilometres! But hopefully we'll manage to stay in orbit a bit longer than that.Is there a central record of the research by all the satellites that were put up?
There's not really any central record. For a start, not every satellite is doing research, communications satellites are a good example. Even then, some communication satellites would be funded by nations but a lot of them are commercial endeavours and companies might consider anything that they learn from operating a satellite to be commercially sensitive and not want to share it.
But of the satellites that were intended to do scientific research, that would work exactly the same way that science in general works. There's no central record, but different disciplines of science would have a small number of scientific journals that are well respected within that discipline. And the scientists that work on the satellites will want to publish their research in the most well respected journals that get the most subscribers so that their work has the most influence.Could we be researching something already researched?
Possibly, but it's incredibly unlikely. Again, this works the same way that science works. When you have an idea, or you decide you want to research a certain topic, the first port of call is the library (or the internet). You do a literature review and you try to learn as much as possible about that topic from other people's research. Once you've done your literature review, you might identify a gap in the collective knowledge of science and decide you want to answer some of the questions that no one knows the answers to. Could some one have researched it before and kept the answers to themselves? Maybe. I think it's unlikely because scientists will want to publish to make sure that their name is associated with this knowledge and they get the proper credit for discovering it first. But even if it had already been researched, if that knowledge was kept private then it could be worth researching it again so the knowledge can be made public.
Philosophically speaking aside, we've got a lot of new technology on board that take advantage of new advances in in materials science so it's very unlikely anyone has ever put together anything quite like this before. And we're going to use the data it collects to do astrophysics and study exploding stars in other galaxies. I can say with absolute certainty that if we see a new gamma-ray burst from another galaxy, no one has ever seen that before!
Thanks for the questions! 0 -
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We'll also shake the crap out of it to simulate launch and make sure it doesn't fall apart.
I love this line. I have visions of a postgrad shaking the device like a cocktail shaker.
I was coming in here to ask you about how what are doing might compare to CubeSat, something I have great interest in and then I see you are using CubeSat. Do you have to assemble it in a cleanroom-type environment?
One of the things the space race in the US has had an effect on is the spin-off industries, with those that work on such programmes having very transferrable skills, plus the potential for spin-off companies. While I acknowledge we are very much at the embryonic stage here in Ireland, do you see potential to develop a "space industry" here?
Now if I could only convince my educational institution to get interested...0 -
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I wonder where the name "Watcher" came from....
There are a couple of reasons that Watcher should be called Watcher.
It was designed to study Gamma-Ray Burst afterglows. GRBs were first discovered in the 60s by the US Vela satellites which were designed to detect violations of the nuclear test ban treaty. Vela is of course a constellation, but velar can also mean to ensure or to watch i.e. in the sense of watching out for the violations. So its name could be in tribute to the discovery of GRBs.
Watcher is at the Boyden Observatory near Bloemfontein in South Africa. Bloemfontein is the birth place of J. R. R. Tolkein, so it's name could also be a tribute to the Watcher in the Water outside Moria.
Those stories are often told as to how Watcher got it's name, but I'm starting to suspect you've played Dungeons & Dragons with Prof Hanlon and know the real reason!
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I love this line. I have visions of a postgrad shaking the device like a cocktail shaker.
While postgrads are a lot cheaper than a proper vibration test table, they just can't reach the frequencies we need! We'll be testing in facilities at Resonate Ltd in Newry as well as at the European Space Research and Technology Centre (ESTEC) in the Netherlands.
We'll also be doing thermal environment tests and these tests are often collectively called "Shake & Bake".I was coming in here to ask you about how what are doing might compare to CubeSat, something I have great interest in and then I see you are using CubeSat. Do you have to assemble it in a cleanroom-type environment?
Yes, but not to a very high standard of clean. We'll need a class 100,000 cleanroom for the flight hardware. We're hoping to kit out a room on the bottom floor of the UCD Science Centre which already has a large glass wall. That way the public will be able to watch us work and see what we're building.
GMOD, the gamma-ray module, has some optical components and for that it's usually recommended to assemble in a class 10,000 cleanroom. But that assembly shouldn't take too long so we'll perform it in another borrowed cleanroom and once all the optical interfaces are safely on the inside of the GMOD enclosure, we can transfer it to our own one and integrate it into EIRSAT-1 there.One of the things the space race in the US has had an effect on is the spin-off industries, with those that work on such programmes having very transferrable skills, plus the potential for spin-off companies. While I acknowledge we are very much at the embryonic stage here in Ireland, do you see potential to develop a "space industry" here?
Now if I could only convince my educational institution to get interested...
The space industry already exists in Ireland, primarily due to our membership of ESA. As you might know, ESA have a policy called geo-return. Money that Ireland spends on ESA is money spent in Ireland by ESA. But the industry is nowhere near as big as it could be and one of the stated goals of the EIRSAT-1 mission is to change that.
We need more graduates with the knowledge and skills necessary to compete in the space industry and make Irish universities and companies more competitive in the global space industry. We think that the best way to achieve that is by to get first hand experience of actually building and operating a spacecraft.
Thanks for the great questions!0 -
Love how full English name also happens to almost spell out Éire !
is a coincidence?
Absolutely not!
In fact, when we were pitching the EIRSAT-1 concept to ESA, one of the first things we explained to them was the meaning of the name. This is Ireland's first satellite and the name reflects that it is a satellite 'of Ireland'. And with the collaboration between UCD and QUB, when we say Ireland, we mean all of Ireland.0 -
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Join Date:Posts: 29920
I couldn't possibly comment. >.>
I absolutely love the practicality of testing the satelite by shaking it around the place... after all the clean rooms, testing, backups and fail overs that are planned, the idea of the team picking it up and giving it a good shake around is somehow hilarious!
Weird coincidence, the first company I formed (the one which built Boards!) also built ESA's Space-to-Earth website for taking space tech and re-engineering it for Earth use... my favourite is the company who makes the monitoring vests for the astronauts repurposed them to monitor the vital signs of premature babies... how cool is that!0 -
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What is the orbital period? and will it be visible from the ground using mark one eyeballs?
The orbital period will be approx 92 minutes. I'd say it's probably not going to be visible to the naked eye. If you get really lucky you might catch a reflection of the Sun off one of the solar panels or something, but it's not something that would be predictable or that you could rely on happening.No chance of retrieving it at end of mission I suppose only it would be great in a big display in the Uni. (Or anywhere suitable)
Sadly no. It's launched with some (small) velocity from the ISS so that means that the distance between the two will just continue to grow. As well as that, EIRSAT-1 will be in a decaying orbit due to atmospheric drag while the ISS is re-boosted periodically to maintain its altitude. Also, EIRSAT-1 isn't designed with the correct grapple (or any grapple for that matter, it just has the rails it needs to smoothly exit the deployer) to allow it to be picked up the robotic arms on the ISS.
It would be amazing to have the real thing on display after having been in space. But realistically, there's not a lot of stuff that goes up there that comes back in one piece. We'll just have to make do with maybe the engineering model or some other mock-up.
Thanks! 0 -
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DublinDilbert wrote: »What about using a USB Digital TV receiver (<€10) and a raspberry pi? maybe just write the messages (with a time stamp) to the SD card in text so students could view them. The DTV receiver shouldn't have a problem demodulating in UHF as they are used by the likes of flight radar 24 for the plane transponders.
Yeah, it's a nice idea to be able to do it so cheap, but I think realistically a lot of people need to tweak their RTL setup quite a bit before they can reliably receive satellite transmissions. A lot of the RTL dongles are cheaply constructed and might need additional shielding or filters or amplifiers.
It's definitely possible, but we'd prefer not to be recommending what could be a frustrating experience to a first time user.DublinDilbert wrote: »How much RF power will you be transmitting the down-link at? What range do you expect to get?
Maximum transmit power is 2W. For our ground-station with high-gain antennae that track the space-craft we're more worried about maintaining line-of-sight so we estimate about 1000km downrange before it's too low on the horizon. Would a lot less for the average person out in their back garden with a turnstile antenna or something.
Thanks for interest and the suggestions! 0 -
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