Cube in cosmos, at war with magnetic field

Photo: Estcube / Mart Noorma

Happy birthday! Today, Estonian space conquest by our very own and very first satellite EstCube-1 is one year old.

By the end of its initial year in space EstCube-1 has gained a lot of wisdom, assure its operators on Earth. Step by step, they are edging towards the main experiment – but a foe hath emerged, a magnetic field developed by components of the cube.

«Finally we understand how the satellite behaves and we’re able to operate it,» said the main engine of the project, Mart Noorma.

Doesn’t sound like much, but polishing the mutual understanding has taken hundreds of working hours. Thanks to the satellite know knowing precisely, at any moment, where it’s at and what it’s doing, we’ve got the photo here of Estonia – straight from the cube.

The picture is just a few weeks old. Over these past months, it was not incapacity of the satellite that hindered it taking the shot; rather, it was the clouds above the home country.

The year captures a lot, including Postimees’ Person of the Year title for Mart Noorma. Not a week goes by without the team having a presentation, at some leadership conference or a lesson at a school. The limelight aside, they do have some technical achievements to show off: 2,500 communications sessions; 19 software updates; about 180 photos sent to Earth; 17 scientific articles; three start-up companies.  

Now, a shot of Estonia also taken, only The Main Goal remains – testing the roll-out of the solar sail wire. Though originally hoped to get done within a couple of months, the experiment has still not started; even now, Mart Noorma will not set a fixed date.

«We haven’t delayed just to delay; the test has been postponed in the process,» says he. «The sooner we get it done, the better; but on the other hand we have a choice to make, as we cannot do all at once. Thanks to all other subsystems, the entire time has been altogether fruitful.»

These days, the EstCube’s copy located at the Tõravere space lab of Tartu Observatory is being tested ever so often. The aim being to find out how to get rid of the magnetism developed in some components of the cube. That’s the very thing hindering the solar sail experiment the most.

The culprits are known: the battery cases, and the bolts at the corners of the structure. The materials of both contain iron, and the iron has magnetised. At the beginning, they did want titanium bolts, as admitted by camera team chief, University of Tartu computer science Master’s student Henri Kuuste. Failing to get these, ordinary ones had to be used.

The persistent magnetic field inside the satellite hinders its operation.

«We are trying to direct the satellite by creating a magnetic field which would relate to that of the Earth,» explains Mr Kuuste. «Right now it seems that the magnetic field that we are able to create is smaller than the persistent magnetic field in the cube. Our attempts to direct the thing had very little effect.»

According to Mr Kuuste, two solutions exist. The first being demagnetising the components.  

«We have to test it in the lab, whether and how it’s possible. If possible, we’ll be able to direct the satellite however we desire. If not, we will have to work with the magnetic field that it has. We’ll be able to direct it in certain directions, but not all.»

To demagnetise, they might try and create a neutralising magnetic field with the electromagnets meant to direct the cube.

«There is a limit to the strength of the magnetic field we could create by these coils,» says the satellite’s control system developer, a Latvian named Andris Slavinskis. «That may depend on how much electricity we have. There’s also a limit to the frequency, how fast we can change polarity. These are the two limitations. I hope we can get something done within these limitations.»

The other option would be to try to carry out the experiment as it is; then, however, the existing magnetic field will not let them measure whether the charged wire rolled out has the desired effect.

«We are striving towards the perfect adjustment; however, there are other ways to measure the effect of a solar sail,» said Mr Slavinskis. By measuring, for instance, how much the sail cord slows down the satellite and brings its orbit lower.

«Right now it seems there is nothing that would exclude the success of the electrical solar sail experiment,» notes Mart Noorma.

«The mission as such has proven more successful than we ever hoped it could be, as it is educational by nature,» adds Henri Kuuste. «All other goals have been achieved. With the platform we have in space, we can do all kinds of tests and educate people.»

«A very large part of the components have not been in space before; thus, all kinds of radiation and space environment effects are of interest to us and to producers of the components,» says Mr Kuuste, pointing to another added value.

Constant work has been going on to also update the satellite software. Going up, the cube had as simple and foolproof a software as possible – to avoid problems, and also because software development was scheduled for the final phase of the satellite.

Thus, the software of the computer-in-cube has been updated ten times; thanks to that, the thing is a lot smarter now. Seven updates have been applied to the power system software, and two to the camera software – the latter now able to independently judge if a shot is worth sending down to Earth.

«Until August, we did random shots, just to see what happens to be caught on camera,» relates Mr Kuuste. «In August we gave the camera the first update, adding the photo evaluation software. Now, the camera is more-or-less able to understand what the picture holds. The moment we got the satellite ready to be positioned, and were able to set timing to the pictures, came around January.»

As underlined in harmony by Mr Kuuste and Mr Noorma, the project is of value for education’s sake. Mr Noorma is of the faith that the approach whereby students had to develop the solutions on their own (and still have to solve operational problems) is what university education will look like in the future. And, by that, he’s in a bit of an opposition to the Finnish student project Aalto-1, where science has taken fist place and the components are outsourced, rather.

As a fruit of the EstCube-1 ideology, they point to a start-up created by team members Erik Kulu and Paul Liias, a recent winner of Vega Foundation support created by University of Tartu. And that’s just one of the three companies so far sprouted from the cube-project. «There’ll be more,» prophesies Mr Kulu.

The start-up was birthed by the realisation that lots of teams and even firms building nanosatellites like EstCube do not include mechanical engineers. 

«Nanosatellites are so small that if you want to do something big with them, you must invent new mechanical solutions. Like cameras telescoped out of the satellite, or solar panels which unpack themselves [thus becoming bigger],» explains Mr Kulu.

«Lots of teams have problems to get solutions at a normal price and simple to use,» says Mr Kulu. And here’s where the Kulu/Liias company steps in. «We’ll be producing mechanical solutions for nanosatellites and offering services.»

The first mission to test their solutions will probably be EstCube-2. And the EstCube-3! Both, as Mr Noorma assures me, have been in development for an entire year already. Even so, he says it’s too early to leak a word on what the next satellites will be doing, and when.

But one thing is sure and certain: reaching ever higher.

EstCube-1 in numbers

5,600 laps around the Earth

2,500 communication sessions

180 photos sent to Earth

19 software updates

17 scientific articles

6 danger situations with space debris

3 start-ups