These Swarming Satellites Are Mapping Earth's Magnetic Cloak

You can't see it with any ordinary telescope, but without the Earth's magnetosphere—the magnetic field that encases the planet, blanketing it against gusts of deadly solar radiation—life here would have been all but impossible. Yet for as vital as it is to our survival, we understand very little about the magnetosphere. And that's where these three gnarly robotic beasts come in.

They're known collectively as the Swarm project, a European Space Agency plan to study the Earth's magnetic field from space. Each identical swarm satellite is covered in solar panels and equipped with some of the most advanced magnetometer technology ever devised at the tip of a 15-foot boom. Incredibly, not a single component on any of the Swarm is magnetic, as it would throw off the sensor's delicate readings.

As IEEE explains:

The device uses low-density helium as its sensor, and exploits the Zeeman effect—the splitting of the element's emission-spectrum lines in a magnetic field.

To measure this spread, the ASM first applies radio frequency energy to lift electrons from their ground state to a metastable intermediate energy level (actually, one of three levels, since the Earth's magnetic field splits this level into three levels, depending on the combined spins of the atom and its electrons).

Then a linearly polarized laser beam further pumps electrons to an even higher, though very short-lived, excited state. In one-tenth of a microsecond, the electrons drop back into one of the metastable levels, giving off photons and creating three closely grouped spectral lines (clustering at around 1083 nanometers wavelength in the infrared). The gap between the lines is proportional to the ambient magnetic field.

The trio of satellites launched on November 22nd of this year and are currently beaming back valuable readings from Earth's core, mantle, crust and oceans, as well as its ionosphere and magnetosphere. Researchers have already begun analyzing it in the hopes of not just garnering a better understanding of the magnetic field, but also uncovering new insights as to how the field interacts with the Earth itself as well as developing more robust navigation systems, more accurate energy resource location, and maybe even helping predict earthquakes. [ESA via IEEE - Image: ESA]