Solar Orbiter, a new collaborative mission between the ESA (European Space Agency) and NASA to study the Sun, launched at 11:03 p.m. EST February 9 on a United Launch Alliance Atlas V rocket from Launch Complex 41 at Cape Canaveral Air Force Station in Florida.

In the first two days after launch, Solar Orbiter was slated to deploy its instrument boom and several antennas that will communicate with Earth and gather scientific data.  Solar Orbiter is on a unique trajectory that will allow its comprehensive set of instruments to provide humanity with the first-ever images of the Sun's poles.  This trajectory includes 22 close approaches to the Sun, bringing the spacecraft within the orbit of Mercury to study the Sun and its influence on space.

Solar Orbiter will spend about three months in its commissioning phase, during which the mission team will run checks on the spacecraft's 10 scientific instruments to ensure they are working properly.  It will take Solar Orbiter about two years to reach its primary science orbit.

Solar Orbiter combines two main modes of study.  In-situ instruments will measure the environment around the spacecraft, detecting such things as electric and magnetic fields and passing particles and waves.  The remote-sensing instruments will image the Sun from afar, along with its atmosphere and its outflow of material, collecting data that will help scientists understand the Sun's inner workings.

During the mission's cruise phase, which lasts until November 2021, the spacecraft's in-situ instruments will gather scientific data about the environment around the spacecraft, while the remote-sensing telescopes will focus on calibration to prepare for science operations near the Sun.  The cruise phase includes three gravity assists that Solar Orbiter will use to draw its orbit closer to the Sun:  two past Venus in December 2020 and August 2021, and one past Earth in November 2021.

Following its Earth gravity assist, Solar Orbiter will begin the primary phase of its mission – leading up to its first close pass by the Sun in 2022 – at about a third the distance from the Sun to Earth.  Throughout its mission, Solar Orbiter will use successive Venus gravity assists to draw its orbit closer to the Sun and lift it out of the ecliptic plane.

ESA's European Space Research and Technology Centre in the Netherlands manages the development effort.  The European Space Operations Center in Germany will operate Solar Orbiter after launch.  Solar Orbiter was built by Airbus Defense and Space.  The spacecraft contains 10 instruments. Nine were provided by ESA member states and ESA.  NASA provided one instrument, the Solar Orbiter Heliospheric Imager (SoloHI), and an additional sensor, the Heavy Ion Sensor, which is part of the Solar Wind Analyzer instrument suite.