Prof. Christine Charles and the Cubesat Team at ANU

 

Last week I sat down with Prof. Christine Charles, Director of the Australian National University’s Plasma, Power and Propulsion group to discuss their latest exciting project; the Australian CubeSat contribution to the international QB50 mission collaboration. With over 20 years of experience in plasma physics, during which time she invented the Helicon Double Layer Thruster design for satellites & interplanetary space travel, and received the 2009 AIP Women in Physics Lecturer of the Year award, Prof. Charles has immense knowledge in the field and has been spearheading the ANU side of the collaboration.

Could you briefly describe the QB50 project and Australia’s contribution towards it?

QB50 is an EU project, which started a few years ago with the aim to launch 50 CubeSats built by 27 countries into space in order to study the lower thermosphere and ionosphere; layer around 90 – 400km. In this area there’s a lot of drag and absolutely no data, so because of that we can’t launch and maintain in orbit any (larger) satellites in that area at the moment. What they wanted to do was to have a mission with low-cost access to space, and so the best platform was CubeSats – which was originally designed for students, so with QB50 we often have student teams supervised by researchers. Because of that, CubeSats and the QB50 project overall is a totally open source we have Chinese, American, Australian teams etc… all sharing their work! Here in Australia, we have 3 teams: Adelaide University, University of New South Wales [UNSW] and a joint team between University of Sydney, UNSW and ourselves here at ANU. We tested our own CubeSat and built a ground control station for it.

So when you say open-source does that mean all these designs and information are available to the public?

Yes, that’s right – so you can actually access all of the designs on the QB50 website.

So for all of these CubeSats to have cheaper access to space, each needs to host 1 European payload out of a choice of 3. These payloads are really great because they’re related to plasma physics (our department); we have Langmuir and ion flux probes and a mass spectrometer. These are to measure that part of the atmosphere – the ionosphere – specifically. The idea is that you have 50 of these CubeSats launched from the International Space Station, and they’ll gradually fall down to 90km over a period of a year. So we’ll have 50 different sets of measurements of electron density, atomic and ion species in the atmosphere, spatially spread in a string of pearls. In addition to that – each CubeSat can have its own individual payload; ours have a radiation counter, a dosimeter, a nano-photonic spectrograph and a custom-made GPS. So there are different experiments being carried out simultaneously, and we’ll learn about atmosphere diagnostics, ground calibration (which is happening here in our lab). Some of these CubeSats are also testing out different propulsion systems as a sort of proof of concept demonstration. You can read about all of these objectives on the QB50 website if you’re interested.

What’s the kind of applications to having all these different sets of data for the ionosphere?

Anything to do with climate science, solar wind, solar radiation, drag – basic and applied physics on this atmospheric medium, which is a plasma medium. For example, all of these payloads, which aren’t usually available commercially, needed to be miniaturised to fit the platform. So the team developed a lot of technology just for it to be tested in space. Miniaturisation is key because, in the future, we’ll aim at low-cost access to space utilising clusters of CubeSats such as these.

Flowing on from that, what were some of the hurdles that the ANU and QB50 project had to overcome to achieve this goal?

Lots and lots of hurdles! You have the technological hurdles, the financial hurdles, human resources hurdles…what I find really impressive is that the budget is very small. So each individual team doesn’t have a lot of money, and everyone is really stretched. What’s really interesting is that some CubeSat parts are available commercially, however, some of these parts are very fragile and are coming from small companies with limited expertise or resources, and so we ran into interesting technological problems. We were quite lucky with the parts we sourced from two different suppliers; one of them ended up not being compliant with the standards we required but the supplier gave us a replacement which was nice, but you still have all these deadlines and suddenly you’re very pushed for time. The universities are not yet used to all the documentation like launch certificates, approvals etc… and that’s because this whole project is very new, it’s the first time someone’s done anything like this. And yet, it’s still going really quickly!

With a normal space mission, you’d have perhaps 10 years between a concept to launching into space. QB50 is on a much shorter timescale, however, which is really great because you can get students genuinely involved with the whole project in their undergrad. ANU signed onto the project about 8 months ago and since then we’ve definitely learnt a lot, so next time we’ll be getting the whole thing done much faster, definitely within a year. The great thing is that you have all these international teams helping each other; so if you’ve got a problem you can hop online to the forums and ask if anyone has run into similar sort of problems and get answers back really fast.

To me, this is one of the greatest projects I’ve ever seen in my over 30 years in academia. It’s all open source, all countries that wanted to get involved had the opportunity, and we have mostly undergraduate students getting involved!

Right, so it seems like you have a lot of undergraduate students helping out and doing much of the work?

That’s right, and one of the hurdles with undergrads is that they have their courses at the same time; they’re doing this project on top of everything because they’re fascinated, but sometimes you can’t just push them too much either, so the resources are stretched from all angles. From undergrads to us (the academics) doing the documentation, to BKI sorting out all these international teams…it’s really full on.

The great thing is that we have all this infrastructure in Australia to design, build and qualify a satellite. Our laboratory, in collaboration with all these others – we’re all plasma physicists and engineers. We’ve been working on designs for propulsion systems for satellites for many years and have had the infrastructure to test these systems and satellites, so the QB50 project fitted really wonderfully here. In particular, we have a very large vacuum thermal testing chamber called Wombat XL which we can use to space qualify satellites and propulsion systems…lots of things!

What was the extent of the preparation for a project like this, and how rigorous was the sort of testing that you mentioned?

It’s very, very rigorous. So we had to do what’s called a thermal vacuum test; these satellites go through a thermal cycle and you do a performance test at the same time. You have vibration and shock tests, all sorts of things. In terms of hurdles, a great example is the vibration tests which are in order to make sure the satellites will survive launch, so a lot of work went into that. Once all the experiments are done you’ve got to upload all the data to the QB50 servers and write a report and documentation etc etc, and so right now we’ve succeeded in all of that and are doing the final end-to-end software check before shipping the satellites to Europe in a couple of weeks.

When can we expect to see these satellites in space?

About the end of the year, it’s very close. The project started a few years ago but we got onto it just 8 months ago. The team got reformed last year around September, and we received the parts around December. Since then we’ve done all the testing necessary; USyd is leading the project and providing the physics payload, UNSW is provide the spacecraft design and operational software and we at ANU are providing the satellite essential parts, the thermal vacuum and vibration test and the ground station operation.

You mentioned one of the big appeals of CubeSats is that they’re low-cost…are there any other particular appeals of this platform?

Yeah, it’s not just to get measurements; now we have the chance to redefine 21st-century experimental space physics, education and training in aerospace. It’s essentially a disrupting technology, because it provides lower cost access to space, and pushes everyone to miniaturise every system they have which is very very trendy now. You try to put as much information in as small a space as possible. This really fits with all the new components which are available these days commercially so it’s all right there.

What’s the future of CubeSat technology for you guys?

Because the timescale is much shorter, you can really design all these new kinds of plasma experiments for space too, so for us, the end goal is testing out our propulsion systems in space. This is doable because of how CubeSats are modular – you can have 2, 3, 8, 16 modules each of which are but 1kg. So these ones don’t have a plasma propulsion system, but we’ve been working on a module which would fit a one-unit CubeSat and provide propulsion to increase mission life. Not only that, but you have increased flexibility in orbit, altitude control, so it really would open doors for more missions. A lot of people are trying to achieve this with various concepts, some of which have flown on precursor missions like the ion spray design by Massachusetts Institute of Technology, or plasma arc system by other universities in the US, and we’re trying to fly our own Pocket Rocket design and prototype. Amelia Greig one of our students who finished her PhD here recently, studied the propellant heating mechanism in our first prototype. For us, that’s really the big aim, because if you can crack that, you can provide very, very low-cost propulsion systems.

Talking broader scale now, how do you see these CubeSats being used by the public in the near future?

I think that if people, individuals, schools, universities, agencies – if they want their own CubeSat they can. At the moment, the total cost for designing, building and qualifying a CubeSat for space is about $100,000 AUD, which is like the price of a nice 4WD, so it’s not crazy. There’s a lot of associations which would even propose schemes for free space launch, or a really cheap launch by piggybacking on another launch. There would certainly be launch opportunities. So if someone really wanted their own satellite with their name or ashes or something like that, that’s definitely a possibility – I think it’s gonna happen! The cost is in the development, but the actual parts like the chip for the onboard computer are not expensive, the development and space qualification is expensive. But other than that the rest isn’t so costly. I think very soon as we streamline the process we’re going to see the price drop right down.

In the past couple of years, we’ve seen space ventures such as SpaceX really take off. What do you think the cause of that is and do you see the incorporation of more commercial endeavours to be a good thing for space research and industry as a whole?

Yeah, I think it’s great! I mean you look at the European Space Agency (ESA), they launch big satellites and everything is really expensive, and you’ve got to go through all this documentation…it’s really inefficient. But for example, there was a small startup which began at the University of Surrey in the UK called Surrey Space Technology Ltd. They went from nothing to the most successful small company which could launch satellites, and they did that by removing all those big, expensive, drawn out restrictions that ESA was doing, so they demonstrated that you could design, build and launch a satellite quite quickly and for an order of magnitude cheaper. Airbus bought that company because it was so successful. The big elephants like ESA and NASA play a role, but they shouldn’t play the whole role, so the CubeSat technology really allows for this sort of innovation. It’s the same sort of thing now with NASA and SpaceX collaborating.

Once the CubeSats are up in orbit, what will the extent of your team’s involvement continue to be?

Oh, lots and lots of things! So first you’ve got to talk to these CubeSats and get commands and data up and down, which we do with a network of ground stations. We’ve developed our own ground station here – so that’s one aspect. Then you’ve got all this scientific data so you’ve got to discuss with everyone interpretation of measurements and how to orient the satellites to take more measurements, and so on. It may be that things will fail too so you’ve got to be ready to fix that sort of thing too. Plus all that development we’re doing in parallel, we’re trying to get funding and thinking ahead for the next mission. The immediate project for us would be a 3 unit CubeSat where one module is our Pocket Rocket propulsion system. We’ve done it once so we’ll be able to do it again but faster, cheaper and with more challenging technology. So if anyone wants to fund this – that’d be really great!

 

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