Cluster II is a space mission of the European Space Agency, with NASA participation, to study the Earth's magnetosphere over the course of nearly two solar cycles. The mission is composed of four identical spacecraft flying in a tetrahedral formation. As a replacement for the original Cluster spacecraft which were lost in a launch failure in 1996, the four Cluster II spacecraft were successfully launched in pairs in July and August 2000 onboard two Soyuz-Fregat rockets from Baikonur, Kazakhstan. In February 2011, Cluster II celebrated 10 years of successful scientific operations in space. As of October 2020, its mission has been extended until the end of 2022. China National Space Administration/ESA Double Star mission operated alongside Cluster II from 2004 to 2007.

Ariane 5 is a European heavy-lift space launch vehicle developed and operated by Arianespace for the European Space Agency (ESA). It is launched from the Centre Spatial Guyanais (CSG) in French Guiana. It has been used to deliver payloads into geostationary transfer orbit (GTO) or low Earth orbit (LEO). The launch vehicle had a streak of 82 consecutive successful launches between 9 April 2003 and 12 December 2017. Since 2014, Ariane 6, a direct successor system, is in development.The system was designed as an expendable launch system by the Centre national d'études spatiales (CNES), the French government's space agency, in close cooperation with Germany and other European partners. Despite not being a direct derivative of its predecessor launch vehicle program, it is classified as part of the Ariane rocket family. Airbus Defence and Space is the prime contractor for the vehicles, leading a multi-country consortium of other European contractors. ESA originally designed Ariane 5 to launch the Hermes spaceplane, and thus it is rated for human space launches.

Since its first launch, Ariane 5 has been refined in successive versions: "G", "G+", "GS", "ECA", and most recently, "ES". The system has a commonly used dual-launch capability, where up to two large geostationary belt communication satellites can be mounted using a SYLDA (Système de Lancement Double Ariane, "Ariane Double-Launch System") carrier system. Up to three, somewhat smaller, main satellites are possible depending on size using SPELTRA (Structure Porteuse Externe Lancement Triple Ariane, "Ariane Triple-Launch External Carrier Structure"). Up to eight secondary payloads, usually small experiment packages or minisatellites, can be carried with an ASAP (Ariane Structure for Auxiliary Payloads) platform.

After the launch of 15 August 2020, Arianespace had already signed the contracts for the last eight Ariane 5 launches, left to launch before the transition to the new Ariane 6 launcher, according to Daniel Neuenschwander, director of space transportation at the ESA.