“You need to give me your phone, wallet and watch,” says the man behind the desk. ”You also need to take off your belt”. Not phrases you would normally want to hear from someone in uniform.
Stripped of valuables and dressed seemingly for surgery – in overshoes, a hat and gown – I am told to stand in front of a sensor for testing. I wait as the man studies the numbers on his computer screen. Satisfied, he lets me through the door.
Inside is a vast hall, around the size of a football pitch. This brightly-lit, three-story high “clean room” at Munich-based space company IABG is mostly empty; except for a cordoned-off area in the centre. Here, displayed like a unique piece of sculpture, are three of the most precise, delicate and fragile-looking satellites I have ever seen. They resemble giant, mechanical insects with glinting angular bodies attached to long extending arms. Together, these satellites make up Swarm – a European Space Agency (Esa) mission designed to map the Earth’s magnetic field with unprecedented accuracy.
To ensure the magnetometers on the three Swarm satellites measure only the Earth’s magnetic field, the spacecraft have been built in an environment free from all magnetic interference. Even the slightest source of magnetism – like a stray metal spanner or slightly magnetised bolt – could damage the instruments. Every magnetic field the satellites themselves generate, as a result of electronic components, has been precisely calibrated.
“We have been as careful as you can imagine,” says my guide, project manager Albert Zaglauer. “Even the glue that holds them together had to be tested.”
Disappearing act
So, if you forget to leave your slightly magnetic smartphone or credit cards at the door, you could set back years of work. And it is important work. Despite the arrival of new technologies, a surprising number of people – and businesses – still rely on a magnetic compass for navigation.
“Back in the 1700s it was the thing you would use,” says Richard Holme, Professor of Geophysics at the University of Liverpool. “In the 1930s, navigating by the Earth’s magnetic field was still important, now it’s become a less important part of things because of GPS. But if you get something that messes up GPS or you get really bad weather so you cannot pick up the GPS signal, then the magnetic field is the only game in town and is still used in ships and planes to determine the heading.”
Our magnetic field is constantly shifting. Keeping track of these changes is vital to ensure compasses in ships or aircraft are accurately calibrated. But in the last 150 years the field has also weakened by 10%. This weakening is particularly prevalent in an area of the southern hemisphere, known as the South Atlantic Anomaly. If this process continues, then the field could reverse. North will become south and south become north. There is evidence that this has happened many times in the past, so it could happen again.
However, there is another reason why we should care about a weakening of the Earth’s magnetic field and it goes to the heart of the existence of all life on our small blue-green planet. The Sun continuously spews out a stream of charged particles, known as the solar wind, and the occasional more violent burps that we have been enjoying recently from solar flares. Without the protection of the magnetic bubble around the Earth – the magnetosphere – our atmosphere would be at the mercy of these particles. It is extremely unlikely it could be torn away completely, but it makes our understanding of the magnetic field and how it’s changing even more important.
