Ariane 6, ESA
"In November 2012, European Ministers responsible for space, meeting in Naples, Italy, approved the start of preparatory activities for Europe's next-generation Ariane 6 launch vehicle. The objective of Ariane 6 is to maintain guaranteed autonomous access to space for Europe, while minimising exploitation costs and suppressing any support to exploitation."
Baseline configuration selected
The selected 'Multi P linear' concept is based on a lower 'composite' of four motors, each loaded with around 135 tonnes of solid propellant, providing also synergies with the Vega evolution perspectives. An "in-line" arrangement of three will serve as the first stage, while the fourth will be mounted above as the second stage.
The third stage will be an adapted version of the Ariane 5 ME upper stage, equipped with the Vinci engine and specific propellant tanks.
The 5.4 m-diameter payload fairing will be able to accommodate the same volume of satellites as Ariane 5.
... Ariane 6 will benefit from the advances by European industry in solid and cryogenic propulsion, structures, systems, avionics, ground segment and operations through the Ariane and Vega programmes."
Marc's note: I meant to post this a few days ago but with the budget news I held off. This rocket would still be on the drawing board if it weren't for SpaceX and their efforts with the Falcon Heavy. While there's no doubt that the heritage of the Ariane line will help development efforts, I have serious doubts that the Ariane 6 will be able to compete with the Falcon Heavy on price unless it's subsidized. SpaceX has a list price (2012) of $83 million to GTO for up to 6.4 tonnes and $128M for greater than 6.4 tonnes while reports suggest Arianespace is targeting €70 million ($91m) for 6.5 tonnes