In November 2023, Swarm celebrated an impressive ten years in orbit. In that time, ESA’s magnetic mission has honed in on all sorts of mysteries - from tussling magnetic blobs to animal migration.

The three-satellite constellation has been a game changer for scientists, providing measurements of Earth’s magnetic field with unprecedented accuracy. 

Swarm allows us to probe the whole of the Earth system, from the outer reaches of the atmosphere right down to its fiery core. 

Here, in no particular order, are 10 reasons you should be excited about Swarm in its second decade. 

1. Swarm FAST data

Swarm data in near-real time? Yes please!

With Swarm’s tenth birthday came the exciting announcement that FAST data would be made available to users. The processor aims to produce L1B FAST data as soon as Swarm telemetry data are made available, which can be as quick as a few hours (depending on the location of the satellites relative to the ground stations).

The lower time delay opens Swarm data for use in same-day space weather monitoring, and early results suggest the data quality is very good.

FAST data are also now available on the Swarm VirES, a highly interactive data visualisation, manipulation, analysis and retrieval interface.

2. Swarm connects people

Swarm connects communities like iron filings to a magnet.

Not only are Swarm data now open to more space weather users, the versatile Earth Explorer has always had many strings to its bow.

The mission connects solid Earth and space scientists, ionosphere researchers with geologists, and even those studying animal migration.

This is clear just from the themes of the upcoming Swarm tenth anniversary science conference, which include: core dynamics, lithospheric magnetisation, electromagnetic induction and oceans, thermosphere/ionosphere; ionosphere/magnetosphere coupling; and space weather.

3. Swarm’s Essential Planetary Variable

Much like temperature and sea level are Essential Climate Variables, we can describe Earth's magnetic field as an Essential Planetary Variable. It connects to many physical processes in the Earth system, and monitoring it is essential for understanding the state of the planet as a whole.

At the time of writing, the Swarm mission is the single most important asset we have for doing just that.

Magnetic fields permeate and surround the entire Earth, influencing and being driven by many different factors. Fluid motion in Earth's core generates the bulk of the field (in a process we call the geodynamo), which extends out into space and opposes the flow of the solar wind (plasma blasted off from the surface of the Sun).

The region in space dominated by Earth's magnetic field is called the magnetosphere, where complex processes mediate the transfer of energy between the solar wind and the Earth system, regulating, among other things, the appearance of the aurora.

It doesn't stop there. Electric currents in the magnetosphere and ionosphere induce secondary currents in the ground, themselves producing magnetic fields which are dependent on the local geology. Some of the methods we have for assessing local geology involve mapping magnetic fields.

Beyond getting a fuller picture about how our planet functions, these data are used for a range of very pragmatic purposes, from precision navigation to space weather mitigation.

4. Swarm data in your smartphone! 

Like Swarm, your smartphone uses a magnetometer to measure Earth’s magnetic field. It takes information from the magnetic model, which itself integrates Swarm data to keep track of the wandering magnetic North, to correct measurements to true geographic North.  

Speaking of positional awareness, Swarm has also proved handy for understanding why some low-orbiting satellites have GPS blackouts over certain parts of the globe. Ionospheric thunderstorms! 

5. The South Atlantic Anomaly is deepening

Swarm has revealed many mysteries in its ten years in space, and one particularly mysterious aspect of Earth’s magnetic field it monitors is the South Atlantic Anomaly (SAA). 

The SAA is an area between South America and Africa where the minimum magnetic field strength is significantly weaker than average - and it continues to deepen. 

For life on the surface there’s nothing to worry about, but for satellites flying over the SAA the weak magnetic field can pose a problem. Charged particles from the sun, for example, are more likely to interfere with spacecraft and cause technical malfunctions. 

Keeping an eye on the SAA could reveal further insights into the scarcely understood processes happening deep under Earth’s surface. 

6. The Swarm constellation is growing 

Five years ago, our tremendous trio became a quality quadruple when Canada’s CASSIOPE joined the Swarm constellation as Swarm Echo. 

Excitingly, in a few years the quadruple will also be joined by the NanoMagSat constellation One of ESA’s new Scout missions, NanoMagSat has just been approved for development, and will see a trio of 24 kg satellites each carrying Swarm-like magnetometers probing Earth’s magnetic field and ionosphere. It will complement and eventually carry on Swarm’s legacy. 

In the meantime, another partner in magnetic magic is China’s Macau Science Satellite 1. MSS-1 launched in mid-2023, and is set to be joined by another three satellites in the coming years. 

A collaboration agreement between the Macau University of Science and Technology and the Swarm Data, Innovation and Science Cluster means there’ll be plenty of synergy between the two missions. 

A similar collaboration is in place between the Swarm mission and the China Seismo-Electromagnetic Satellite (CSES). The two missions have previously shared calibration and validation activities, and ESA disseminates a subset of CSES data in “Swarm-like” format. 

7. Synergies in space 

When it comes to monitoring the global state of the magnetic field, it is useful to have more measurements from multiple locations. 

Many spacecraft carry platform magnetometers, which are used to determine their orientation in space. The measurements from these magnetometers are not typically useful as scientific data products, but with Swarm’s absolute magnetometer we can recalibrate some of these datasets to significantly improve their accuracy. 

The Swarm mission team currently provides such recalibrated data from several other missions, including fellow Earth Explorer CryoSat, as well as GOCE, GRACE, and GRACE-FO. 

This activity increases the return from those missions, as well as enriching the Swarm mission. 

8. 500 papers, and counting! 

After ten years in space, the rate of papers being published by the Swarm scientific community continues to accelerate year-on-year. By the time we met at the Swarm data quality workshop last autumn, the number was 500 already. 

Already in 2024, we’ve seen papers using Swarm data to measure the response of the ionosphere to both space weather, and to waves propagating from the severe 7.8 magnitude earthquake that happened in February 2023 in Türkiye. 

There are plenty more on the horizon. 

9. An ever-expanding product portfolio 

As well as scientific breakthroughs, the Swarm data, innovation and science cluster (DISC) is constantly working on improved and new data products. 

Amongst the most recent updates, early in January 2024 we heard an update from the Swarm-SWITCH project, which incorporates Swarm data into a handy, interactive space weather timeline viewer. 

Two new Swarm products making use of Swarm’s absolute magnetometer burst mode data were also published, including one to investigate lightning whistlers. 

10. Swerving space debris 

It is getting pretty crowded up where our Swarm satellites patrol the ionosphere, and 2023 was the busiest year yet for ESA’s space debris office. 

In total last year there were 32 escalated events, and seven collision avoidance manoeuvres (CAMs) to keep the flight dynamics team on their toes. That was up from 28 escalations and five CAMs in 2022. 

Compare those figures with the seven escalations and just one CAM in 2015, and you can see how the picture has changed for satellites in low Earth orbit. 

Hold on to your seats for 2024!  

Thanks to Ashley Smith of the University of Edinburgh and the Swarm DISC for the idea and input for this article.