When Roland Lammegger looked up at the stars and planets as a child, Jupiter was his favourite planet because of its size, its numerous moons and its interesting atmosphere with its famous red spot. Years later, as a researcher at the Institute of Experimental Physics at Graz University of Technology (TU Graz), he would probably never have dared to dream that he would invent and build something that would actually make a journey to Jupiter and its moons. From his personal point of view, this has closed a circle. From a scientific point of view, Roland Lammegger’s invention could contribute to providing entirely new insights into one of the most exciting questions facing humanity: is there life outside Earth?
What are Jupiter’s icy moons hiding?
The optical scalar magnetometer called MAGSCA, built in close collaboration over many years between TU Graz and the Space Research Institute (IWF) of the Austrian Academy of Sciences (ÖAW), is expected to launch on 13th April 2023 with the European Space Agency’s (ESA) JUICE (Jupiter ICy moons Explorer) mission from the spaceport in French Guiana towards Jupiter. JUICE has a total of ten instruments on board and will study the moons Ganymede, Europa and Callisto, among others. In this large-scale project, MAGSCA is part of the J-MAG measuring instrument, which is to determine the magnetic fields of Jupiter and the three icy moons and thus provide information on whether there is liquid water under the ice surfaces and thus an important prerequisite for the development of life.
MAGSCA will be responsible for determining the strength of the magnetic fields of Jupiter and its moons with high accuracy. Two vector magnetometers in J-MAG ensure that the direction of the magnetic fields is also determined. A combination of these values then provides very precise information about the inner structure of the moons. “If you know the magnetic field induced in the water exactly, you get an idea of what it looks like inside the body. Besides gravity field measurement, this is the only method that allows us to look deep inside bodies,” explains Roland Lammegger.
Long journey with many dangers
Until then, however, JUICE will be on its way to Jupiter for around eight years, orbiting the sun a few times along the way and performing swing-by manoeuvres at the Earth, the moon and Venus to build up the necessary kinetic energy for the journey to the outer solar system. And on this long journey, as well as at the destination, quite challenging conditions await the probe and the measuring instruments. Outside the near-Earth orbit, there is no magnetosphere to shield the solar wind, temperatures are much lower and Jupiter itself has a very strong magnetic field that also concentrates the solar wind. “There are very large particle streams with high-energy particles that are very hard on the hardware,” says Roland Lammegger.
This is why numerous tests were necessary to equip MAGSCA for these inhospitable conditions. Among other things, the magnetometer was exposed to very strong radiation, doses millions to billions of times higher than one is normally exposed to on Earth. “You can think of it as literally holding the device in a nuclear reactor and letting it be irradiated and then seeing what happens.” It turned out, for example, that the optical fibres originally used in MAGSCA and their plastic cover simply disintegrate and that the glass used in the fibres becomes opaque. After all the tests and preparations, all that remains in the end is the hope that, when it comes to it, everything will work. “You can’t send someone to quickly tighten the screws. More than 20 colleagues with different expertise did their best, but unfortunately there are also enough examples where something went wrong.”
Rubidium atoms in the breast pocket
For Roland Lammegger, the long journey began several years before JUICE, when he developed a method to measure magnetic fields by means of two-photon spectroscopy of free alkali atoms in a purely optical way as part of his dissertation published in 2006 and subsequent research. The new measuring principle was also patented in 2008. What followed after the development of the method, however, was not the direct journey on board a probe to Jupiter, but a combination of several lucky meetings with colleagues from the Space Institute – first and foremost with Werner Magnes – at the appropriate time.
It started when, in the late 2000s, a colleague of Roland Lammegger’s at the Institute of Experimental Physics at the time, Bodil Holst, became very interested in his work and thought that more should be made of it. It was through her that contact was made with the Space Research Institute (IWF). “That was quite interesting. I had a glass cell in my breast pocket filled with rubidium atoms and said you can measure magnetic fields with it. Prof. Baumjohann and Werner Magnes were very enthusiastic about this right away, and that’s how the cooperation got rolling,” he recalls. At that time, however, there was no talk of a journey into space.
Successful proof of space suitability
First of all, the measuring instrument had to be made fit for use in space and for that it needed someone to use it on a mission. This came about through the next happy encounter. At that time, the IMF was considering participating in a Chinese Earth field mission. When Roland Lammegger gave a lecture at the IMF, attended by the scientist responsible for it, it immediately became clear that the scalar magnetometer was absolutely needed for the China Seismo-Electromagnetic Satellite (CSES) probe launched in 2018. This was the first time ever that such an instrument was flown into space and at the same time provided proof that this measuring instrument is suitable for space – and this, fittingly, exactly at the time when the preparations for the MAGSCA project were also getting underway.
But not all the hurdles had been overcome, because apart from the findings from the radiation and stress tests, the first task was to develop the right design for MAGSCA so that it could be used for the mission. According to Roland Lammegger, there were also difficult times when the search for suitable solutions did not lead to the desired result. “Sometimes the path forks and there are two or more question marks and you don’t know how or if it will continue at all. But then you meet someone again who says, I have a solution or let’s try that and that’s how you move forward in the team.”
The consequences of a proof
He also experienced this process as a long journey with all its ups and downs, but during which the team became like a second family to him. And if JUICE should show in the course of its mission that Jupiter’s icy moons do indeed offer the prerequisites for the emergence of life, then Roland Lammegger’s childhood dream of Jupiter would have more than come true. “If this proof is successful, then that would be very exciting. It is perhaps not yet possible to properly assess what the consequences of this would be. It would definitely fuel curiosity and of course then you would see how you could get a sample from there. Knowing that I had made a contribution to make this discovery possible, that would be a great honour in itself.”