Cluster_quartet

The European Space Agency (ESA) has manoeuvred two satellites of the Cluster constellation to study the impact of solar wind on the Earth’s magnetic field.

The agency will study the Earth’s bow shock activity where the solar wind slows down from super to subsonic speeds as it flows around the planet.

ESA space operations centre flight dynamics specialist Detlef Sieg said: "The scientific aim is to have a pair of satellites orbiting a few kilometres apart in the free solar wind just ahead of the bow shock, to collect data at very small scales."

The satellites in the constellation are placed in orbits 600km to 20,000km apart based on the regions that 11 instruments on the satellite are studying.

"This enables us to study physical processes such as plasma heating and acceleration at the bow shock."

Later this month, the satellites 3 and 4 will be realigned to within around 6km of each other. The satellites will pass one another on each orbit within a gap of three seconds apart.

The ultra-close alignment is scheduled to continue until mid-March.

Cluster mission project scientist Philippe Escoubet said: "This enables us to study physical processes such as plasma heating and acceleration at the bow shock.

"Previous studies of the bow shock have shown electron heating over distances as small as 16km, but we want to see what is happening using two satellites at smaller scales."

The other two satellites will be steady around 5,000km away.

In orbit since 2000, the Cluster quartet is designed to study the detailed structures of Earth’s magnetosphere and its environment in 3D.

Image: The Cluster quartet. Photo: courtesy of ESA.