Known as metamaterial Optical Solar Reflectors (meta-OSRs), the coatings are designed to reject solar radiation while at the same time dissipating the heat that is generated onboard satellites and space vehicles. Currently, OSRs are usually made of quartz tiles that combine thermo-optical properties with an ability to withstand the environment in space. However, these tiles are heavy and fragile, adding significantly to launch weight. Furthermore, they cannot be applied to curved surfaces.
The team, which includes researchers from the University of Southampton, patterned metal oxide into a metamaterial with very strong infrared emissivity while retaining a low absorption of the solar spectrum. Using this metamaterial design, the researchers developed a ‘smart’ radiator which allows tuning of the radiative cooling of the spacecraft using another type of metal oxide. The consortium’s work is described in the journal ACS Photonics.
“The meta-OSR technology is entirely based on durable and space-approved inorganic coatings, which can be applied onto flexible thin-film substances with the potential to be developed as a new technology solution,” said Southampton University’s Prof Otto Muskens, the principal investigator of the study.
“Since the assembly and launch costs of OSRs is several tens of thousands of US dollars per square metre, even small improvements in weight reduction can make a significant change to the space industry.”
Supported by a two-year Horizon 2020 space technology project, the University of Southampton is a member of the META-REFLECTOR consortium, which also includes the Italian research centre Centro Ricerche Elettro-Ottiche (CREO), Danish nanoimprint developer NIL Technology and Thales Alenia Space.
“Currently, thermal emissivity control requires bulky mechanical components such as louvers, which are extremely expensive and prone to failure, posing significant risk to missions,” said CREO’s Dr Sandro Mengali.
“The smart meta-OSR technology will offer a valuable new tool for thermal engineers of spacecraft, of particular importance for the lightweight segment of the satellite market.”