Illustration: NASA/JPL

DTU helps NASA map Jupiter's magnetic field

Tuesday 30 May 17


John Leif Jørgensen
Professor and Head of Measurement and Instrumentation
DTU Space
+45 45 25 34 48

The Juno mission

Juno was launched on 5 August 2011 from Cape Canaveral in Florida and went into orbit around Jupiter on 4 July 2016 after a journey covering almost 3 billion kilometres.Juno is scheduled to orbit Jupiter for about five years . While orbiting some distance from the planet, Juno will be sent closer to the planet’s surface for shorter periods. In this way, the extreme particle radiation in the planet’s magnetic field will not destroy the instruments on board the spacecraft. Juno travels at a speed of approx. 96,000 km/hour in relation to Earth.

The main goal of the mission is to study how Jupiter was formed as well as its development by:

  • Mapping out its magnetic and gravitational fields to identify its internal structure.

  • Examining the magnetosphere around its poles to find out more about how the planet’s enormous magnetic fields affect its atmosphere.

  • Looking at how much water its atmosphere contains, which may provide new knowledge about how the planets were formed.

Read more about the mission here:

Jupiter’s magnetic field is very different to what was previously assumed. This is evident from new scientific findings from the Juno mission, which are now being published in the esteemed scientific journals Science and Geophysical Research Letters.

Jupiter, the largest planet in the solar system, is giving researchers back on Earth a few surprises after they can now study the large gas planet at close quarters. The unmanned spacecraft Juno, which is fitted with equipment from DTU Space, has been orbiting the planet since last July and sending huge volumes of data back to Earth.

“The Juno mission has brought us much closer to the planet’s surface than ever before, and as a result we are able to find out much more about Jupiter and its magnetic field,” says Professor John Leif Jørgensen, Head of Measurement and Instrumentation at DTU Space, who is responsible for that part of the mission where DTU is involved.

“Among other things, it appears that Jupiter’s magnetic field differs significantly from the theoretical models which have previously been predicted based on the physics. The structure of the magnetic field is very varied, and doesn’t match the basic model which has been used until now to describe the planet’s magnetic field. It resembles Earth’s magnetic field far less than we thought – in fact, it doesn’t look like anything we’ve seen so far.”

For example, Jupiter’s magnetic field is more than twice as powerful as previously assumed.

These new findings about the planet have just been published in two in-depth articles in the prestigious academic journal Science. Moreover, a number of articles are being published this week in the journal Geophysical Research Letters about several other new discoveries from the Juno mission.

“Perhaps what we’re seeing is the effect of meteorites which in the past have impacted Jupiter’s surface and modified its magnetic field, which is now frozen in a superconducting core. We see considerable variations in the concentrations and weaknesses in the magnetic field, so that they are almost crater-like,” explains John Leif Jørgensen.

Moreover, Juno has also and in great detail shown the very powerful storms that are constantly raging across vast areas. Not just in the form of the well-known Great Red Spot, which is a huge anticyclonic storm, but also extreme weather near Jupiter’s poles.

Juno is designed specifically to look into the gas giant Jupiter. Until recently, the general opinion was that a planet like this was basically homogeneous and relatively simple to model. However, this is not the case.

“Juno’s measurements show that Jupiter has a very complex internal structure with regard to atmospheric currents, internal mass distribution and the structure of the magnetic field. For example, there are signs that the core which ought to exist at the planet’s centre is diffuse or completely dissolved, which is very strange. Consequently, the existing models for gas planets such as Jupiter probably have to be revised,” says John Leif Jørgensen.

One of DTU’s most comprehensive missions

DTU Space has made its mark in a big way on the mission, which is one of the biggest tasks ever assigned to DTU. The mission is costing somewhere in the region of DKK 13 billion in total, and DTU is responsible for approximately one tenth of the mission.

"We’re very proud to be involved in the mission, and especially now with all the important and exciting research findings which are being produced."
Professor John Leif Jørgensen, DTU Space

“We are very proud to be involved in the mission, and especially now with all the important and exciting research findings which are being produced. It shows that DTU and DTU Space are leading the way internationally within this field of research,” says John Leif Jørgensen.

DTU Space has supplied equipment to the mission in the form of four star cameras, which have been used for extremely precise navigation and for taking photographs of Jupiter and some of the areas in space that Juno has passed on its long journey out to the planet. DTU Space has also validated and calibrated the magnetometer on board which NASA’s Goddard Space Flight Center (GSFC) developed to study the planet’s magnetic field.

En route to Jupiter, the star cameras have registered around 1.3 million small objects, with some of them even colliding with the spacecraft at velocities as high as 50 km/second.

“We received some inexplicable data, and when we analysed it, we discovered that Juno had been struck by interplanetary dust particles which move around the universe, and which perhaps can tell us something about the early solar system,” says John Leif Jørgensen, who is publishing this knowledge this week in Geophysical Research Letters in a separate article together with colleagues.

Noise yields new knowledge

In order to navigate, the star cameras must, among other things, be able to eliminate noise in the data in the form of particle radiation. This is possible thanks to software and algorithms developed at DTU. In fact, during the mission, the technology has proved to function so well that it is now being employed in other European and US space missions.

Moreover, the noise actually appears to be yielding new knowledge. By analysing the sorted data, DTU researchers have been able to characterize the very energy-rich radiation that comes from the Sun and which is accelerated to high speeds by Jupiter’s magnetic field. This discovery too has resulted in an article in Geophysical Research Letters.

It is all fundamental scientific research which is helping to shed light on some of the big questions about the origins and evolution of the solar system. For example, we now know that Jupiter has the strongest magnetic field of any planet. But we do not know exactly how this magnetic field was formed, or how it is maintained.

However, we are slightly closer to finding the answers to these sorts of questions with the new findings from the Juno mission.


Jupiter is the biggest planet in the solar system. The remarkable planet has 63 known moons around it and a magnetic field which is 20 times more powerful and 18,000 times bigger than that surrounding Earth.

One feature of the planet’s surface is the Great Red Spot, which is a gigantic storm covering an area three times the size of Earth and which has been observed for at least 350 years.