The Airbus Very High Resolution constellation

Airbus Defense & Space just announced it will launch a constellation of 4 Very High Resolution (VHR) optical earth observation satellites, in 2020 and 2021. This will be a follow-on to the Pléiades constellation, which comprises two agile, 70cm resolution satellites, launched in 2011 and 2012. Unlike Pléiades, which was a public-private partnership between Airbus (the prime contractor), Thales (which provided the instruments) and the French Ministry of Defense, this new constellation will be entirely financed by Airbus.

Pléiades (Airbus Defense & Space, France)

According to the press release, “Pléiades system features will be improved to match the market requirements expected to be the norm at the time of launch”, which I think means the resolution will be improved to 30cm, to match the resolution of the Worldview 3 and Worldview 4 satellites owned by Airbus’  main competitor, Digital Globe. This would be coherent with the studies on the design of 20 to 30 cm resolution satellites carried out by CNES, the French space agency.

These studies led to the ARCTOS concept by Airbus, with a 30cm resolution from 700km up, a 20km swath, and a small enough mass to be launched from a Vega launcher thanks to a lightweight 1.5m SiC mirror. Resolutions higher than 30cm are much more difficult to achieve. Besides, the release calls the constellation “VHR”, which is between HR (around 70cm, like Pléiades) and EHR (extremely high resolution, around 20cm) in the French classification of resolution. Airbus is also the prime contractor for CSO,  a military EHR satellite to be launched around 2020, but this satellite fly will relatively low in order to achieve this resolution, so the technology is probably not mature for an EHR satellite at 700km altitude. CNES, Airbus and Thales are also working together on the OTOS concept, which would use adaptative optics to correct for mirror deformations.

Consequently, it is likely the announced constellation will be made of four 30cm resolution satellites. Since the release states it will provide “intra-day” revisit, this means the constellation will have two orbital planes: from a 700km orbit, two agile satellites on the same orbital plane are required to provide same-day revisit, so two planes are needed.

This constellation will help Airbus catch up with Digital Globe, but the US company has already announced it is designing its next-generation constellation, which will be made up of six 1m-resolution satellites build and operated by the United Arab Emirates and a high-resolution component owned by Digital Globe. The emirati satellites will provide a high temporal revisit, enabling to detect changes  and then cue the higher resolution satellites to characterize these changes. The former are scheduled for launch in 2018 and 2019,  around the same time Digital Globe plans to seriously invest in the latter.

Finally, the release mentions the constellation will be “dual”, which probably means it will be a dual-use civilian and military constellation, giving the French Ministry of Defense  tasking priority when required. This would considerably increase the temporal revisit capability of the French reconnaissance system.

Edit: Spacenews quotes an industry official saying Airbus will invest at least 550m€ in the constellation, the resolution being not set but around 40cm, and the instruments being Airbus-made SiC telescopes.

Update 26 January 2017: Peter B. de Selding reports the satellites will use the EDRS network for laser data relay, enabling near-real time access to the images.

Update 12 May 2017: Airbus will probably use CILAS deformable mirrors for its satellites, as CILAS and Airbus are collaborating on the OTOS program and the technology seems mature.


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