Siân Cleaver
Airbus Defence & Space engineer who gave the first public contractor assessment of ESM performance during Artemis II.
Last refreshed: 9 April 2026 · Appears in 1 active topic
What did the Airbus engineer say about the Artemis II engine burn?
Latest on Siân Cleaver
- What did the Airbus engineer say about the Artemis II service module?
- Siân Cleaver told Nature the translunar injection burn performed perfectly to plan, with precision that eliminated several planned trajectory correction manoeuvres.Source: Nature interview, Day 8 Artemis II
- Did the Orion service module work properly on Artemis II?
- Yes. Airbus engineer Siân Cleaver confirmed the European Service Module performed better than the conservative pre-flight predictions, exceeding expectations on propulsion precision.Source: Nature interview, Day 8 Artemis II
- Who built the Orion capsule service module for Artemis?
- Airbus Defence & Space built the European Service Module under an ESA contract. The ESM provides propulsion, power, and life support for Orion.Source: ESA contract documentation
- How does Artemis II ESM performance affect ESA Gateway negotiations?
- Demonstrated hardware precision strengthens ESA's position at the June 2026 Council, where Director General Aschbacher must present a Gateway recovery plan after its cancellation.Source: Artemis II update #7
Background
Siân Cleaver is an engineer at Airbus Defence & Space, the prime contractor for the European Service Module (ESM) that provides propulsion, power, and life support for the Orion spacecraft. On Day 8 of Artemis II, Cleaver gave the first public quotes from an ESM contractor engineer during the active flight, telling Nature that the translunar injection burn performed "perfectly to plan" and that the precision had eliminated several of the planned trajectory correction manoeuvres.
The European Service Module is a European contribution to Artemis built under an ESA contract awarded to Airbus in 2014. It is derived from the Automated Transfer Vehicle (ATV) that supplied the International Space Station between 2008 and 2015. Each ESM costs approximately €200 million and contains four main engines, 33 thrusters, solar arrays generating 11 kilowatts of power, and life support consumables. Airbus is contracted to build a total of six ESMs for the Artemis programme. The ESM-2, used on Artemis II, was delivered to Kennedy Space Center in late 2023.
Cleaver's confirmation that ESM performance exceeded conservative pre-flight predictions strengthens ESA's negotiating position ahead of the June 2026 Council meeting, where Director General Josef Aschbacher must present a Gateway recovery plan following the programme's cancellation. ESA faces the question of what Artemis contributions it can offer without a destination beyond lunar orbit, and demonstrated hardware reliability is among the few unambiguous assets it brings to that renegotiation.
