Four identical satellites that will study the interactions between solar winds and the Earth's magnetic fields blasted off into space on Thursday and settled into orbit begin a two-year study, NASA said.
The Delta V rocket of the United Launch Alliance lifted off from its launchpad from Cape Canaveral in Florida at 22:44 local time (2:44 GMT Friday) as planned at the beginning a 30-minute window of opportunity.
The quartet of spacecraft weighing 1.2 tonnes known as "Magnetospheric Multiscale" or MMS, will fly in a pyramid formation.
They later eased away from each other successfully.
"Spacecraft separation is complete!" NASA said later in a statement two hours later.
"All four of NASA?s Magnetospheric Multiscale observatories have been released in orbit, where they?ll soon embark on an ambitious mission to unlock the secrets of magnetic reconnection," it added.
They will obtain three-dimensional images and collect data as they monitor collisions from the Earth's magnetosphere and solar particles arriving at high speed and forming their own magnetic field about 60,000 miles from Earth.
Scientists hope to gain a greater understanding of the phenomenon, known as magnetic reconnection.
"Magnetic reconnection is one of the most important drivers of space weather events,? said Jeff Newmark, interim director of the Heliophysics Division at NASA Headquarters in Washington.
"Space weather events can affect modern technological systems such as communications networks, GPS navigation, and electrical power grids."
The $1.1 billion mission is expected to last two years.