Originally scheduled for Nov. 14, the launch of the Swarm mission is expected to be delayed by about one week, the mission's launch service provider, Eurockot, said.
The delay follows a decision to replace a part in the upper stage of the Rockot launcher, ESA officials said.
The three-satellite Swarm mission is intended to study the magnetic field that protects the planet from cosmic radiation and charged particles that bombard Earth in "solar winds," ESA scientists said.
The mission will collect data on many natural processes, from those occurring deep inside the planet to weather in space caused by solar activity, they said.
Details of the exact launch vehicle equipment responsible for the launch delay were not given but ESA officials said more information would be released when available.