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CarbSAR imaging satellite using Wrapped Rib antenna with CFRP structures will be supplied by Airbus for the U.K. Ministry of Defence's Oberon program. Source | Airbus Defence and Space

Airbus (Toulouse, France) has been by the U.K. Ministry of Defence (MOD) to design and build two synthetic aperture radar (SAR) satellites with day-and-night, all-weather, space-based intelligence, surveillance and reconnaissance (ISR) capability. The two Oberon satellites will boast active, ultra-high resolution SAR, providing greater operational capability to British and allied defense forces. Launch is expected in 2027.

A reports that the U.K. has long relied on its intelligence ties with the U.S. to obtain global intelligence data. Oberon follows another contract awarded to Airbus’ (SSTL, Guildford, U.K.) for an Earth observation satellite as part of the Istari project as the U.K. develops its own sovereign ISR collection capability. The goal is to have an on-orbit constellation by ≈2031.

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Airbus has worked with SMEs across the U.K. to leverage innovative technologies for these 400-kilogram satellites. A key example is the antennas which will be supplied by (OSS, Harwell, U.K.). OSS has developed carbon fiber-reinforced polymer (CFRP) structures that stow away in very small volumes for launch but deploy into shape once in orbit. These antennas will use OSS’ Wrapped Rib design to transmit and receive the radar pulses that are used to map the surface of Earth.

“We are looking forward to working with Airbus as our mission partner to deliver this important capability together,” says Paul Russell, Space team leader at the MOD’s procurement department. “As the U.K.’s largest space company, Airbus makes a significant contribution to the delivery of the National Space Strategy, while supporting British SMEs across its supply chains. With the award of the Oberon contract, we will deliver the next in a series of game-changing capabilities to U.K. Space Command.”

OSS has validated its CFRP Wrapped Rib antenna in collaboration with SSTL onboard its CarbSAR satellite. SSTL was formed as a spin-off from the University of Surrey in 1985, and has since specialized in the design, build, test and operation of small satellites. In 2009, SSTL became a wholly owned subsidiary of Airbus. OSS is a venture capital backed, growth stage space technology business founded in 2013 with a vision to be the global leader in deployable antennas for space.

The Wrapped Rib Antenna developed by OSS for synthetic aperture radar (SAR) enables high-resolution imaging for SmallSat Earth observation missions. Source |

In May 2023, OSS and SSTL agreed to build and launch an OSS Wrapped Rib antenna mounted to an SSTL CarbSAR satellite. The goal was to advance both companies’ abilities, with OSS gaining space heritage, and SSTL building its ability to integrate capability from new suppliers. The work has been jointly funded by OSS, SSTL, Airbus Defence and Space, the U.K.’s (NSSIF) and the MOD.

A claimed this collaboration is proving a groundbreaking SAR concept. Surveillance, change detection and “big data” analytics applications are driving interest in spaceborne SAR data to support day/night and all-weather imaging at a rate faster than can be achieved with any individual satellite. This drives demand for much smaller radar satellites that can be launched in groups within a limited launch volume, however it is still desirable to retain a large antenna for better quality imagery.

Having a large, scalable, stowable and lightweight reflector antenna provides a number of benefits in designing small radar satellites for particular applications. A reflector antenna can also significantly simplify the radar electronics, making it ideal for implementation on much smaller spacecraft such as SSTL’s CarbSAR platform.

The OSS Wrapped Rib Antenna enables high-resolution imaging from SmallSat Earth observation missions, irrespective of weather conditions or daylight. These antennas deploy CFRP ribs from a central hub to form a 3-meter-diameter parabolic dish supporting a high-performing metal mesh reflector surface. This technology provides a compact stowed configuration that achieves cost-efficient performance when deployed in orbit. In 2023, the antenna had successfully completed an extensive ground-based test program, including a radio frequency (RF) test campaign, and was deemed ready to demonstrate its performance in orbit.

Carbonite is the latest in a long range of 100-kilogram class SmallSat platforms that SSTL has been building in Guildford since the early 1980’s. Carbonite-1 was a development mission launched in 2015. The Carbonite range was always designed to be multi-sensor and has evolved to feature a standard set of core platform avionics available with a variety of optical payloads, including SAR. CarbSAR reportedly embeds the SAR electronics within the standard Carbonite satellite core avionics in an elegant combination with the stowable OSS antenna to deliver high-resolution, X-band imagery.