Lifting-off from Cape Canaveral, in the US at 0445 GMT on 4 June, a hybrid SpaceX Falcon 9 rocket carried an communications satellite, SES-12, to a Geosynchronous Transfer Orbit (GTO). The satellite, SES-12, is the sixth SES unit to be launched by SpaceX. It is built on the E3000e platform developed by Airbus Defence and Space. It represents an evolution of the current E3000 bus, into an “all electric” bus that solely utilises electric propulsion for its orbit-raising manoeuvre. This means that although the satellite will take almost six months to reach its target location in the Geostationary belt – 95 degrees East – the remaining fuel onboard is expected to last for 22 years.
As a testament to work in progress at SpaceX, the Falcon 9 rocket used for this mission is a “hybrid” between two stages of Falcon 9 development – or “Blocks”. The first stage of the rocket is from the outgoing “Block 4” standard. This stage had already flown once – for the DARPA X-37B/OTV 5 mission in September 2017 – and, like its previous Block 4 compatriots, was only ever going to be reused once (later Block 5 versions are capable of up to ten flights). With no attempt to recover the Block 4 stage planned, this allowed the stage to use all of its fuel to carry the payload into orbit.
The second stage used on the SES-12 launch, was of the newer “Block 5” design standard but this remains expendable. Nevertheless, the company is continuing to investigate retrieval techniques for the payload fairings. For while there was no fairing “catching” attempt on this flight (as there has been for launches from the West Coast), a vessel was dispatched to retrieve the parasail-slowed fairing halves from the surface of the ocean.
Eventually the all Block 5 first stage/Block 5 second stage version of Falcon 9, which debuted in May while launching the Bangladeshi BANGABANDHU-1 satellite, will become the standard workhorse of SpaceX. The Falcon 9 Block 5 will thus be the final iteration of the Falcon 9 before the all-reusable first and second stage BFR launch vehicle takes over. Nevertheless, the Falcon 9 Block 5 is expected to launch hundreds of times more before that takes place.
David Todd contributed to this article