A disappointingly cloudy sky hid most of the launch of the Magnetospheric Multiscale (MMS) mission during its 10:44 p.m. liftoff aboard a United Launch Alliance Atlas V rocket from Space Launch Complex 41 at Cape Canaveral Air Force Station on 12 March 2015.

A United Launch Alliance press release explains the mission:

The Magnetospheric Multiscale mission, or MMS, is a NASA Solar Terrestrial Probes mission consisting of four identical science observatories whose objective is to understand the microphysics of magnetic reconnection.

Magnetic reconnection is a universal process that happens when magnetic fields in two adjacent regions of space interconnect across their boundary converting magnetic energy into heat and high energy charged particles. This process lies at the heart of giant explosions on the sun, such as solar flares and coronal mass ejections, which can fling radiation and particles across the solar system. Because it’s so difficult to see this process on the sun, and it’s also a difficult process to re-create and study in the lab, researchers plan to take a closer look at magnetic reconnection in space.

The four identically instrumented MMS observatories will fly in an adjustable pyramid-like tetrahedron formation. By observing magnetic reconnection in nature, MMS provides access to predictive knowledge of a universal process that is the final governor of space weather, affecting modern technological systems such as communications networks, GPS navigation, and electrical power grids. Magnetic reconnection also limits the performance of fusion reactors on Earth. Solving magnetic reconnection has the potential to unlock understanding of a fundamental energy process present throughout the universe that also affects and limits our use of technologies on Earth.

A ULA Atlas V 421 will deliver the MMS constellation to a highly elliptical orbit (HEO).