ESA’s Phoebus
We’d be remiss to exclude ESA’s Phoebus. It’s not a stand-alone rocket but rather a highly optimized upper stage that’ll be used on future versions of Ariane 6 and other rockets. Phoebus is expected to boost Ariane 6’s payload launch capacity to geostationary orbit by more than 2 tons and lower production costs.
ESA awarded contracts to MT Aerospace and ArianeGroup in May 2019 to develop the Phoebus prototype. Upper stages are typically made of aluminum, but Phoebus will use carbon composites, which will result in the lower cost and contribute to the added payload capacity.
