Development of CFRP mirrors for space telescopes

Abstract

CFRP (Caron fiber reinforced plastics) have superior properties of high specific elasticity and low thermal expansion for satellite telescope structures. However, difficulties to achieve required surface accuracy and to ensure stability in orbit have discouraged CFRP application as main mirrors. We have developed ultra-light weight and high precision CFRP mirrors of sandwich structures composed of CFRP skins and CFRP cores using a replica technique. Shape accuracy of the demonstrated mirrors of 150 mm in diameter was 0.8 μm RMS (Root Mean Square) and surface roughness was 5 nm RMS as fabricated. Further optimization of fabrication process conditions to improve surface accuracy was studied using flat sandwich panels. Then surface accuracy of the flat CFRP sandwich panels of 150 mm square was improved to flatness of 0.2 μm RMS with surface roughness of 6 nm RMS. The surface accuracy vs. size of trial models indicated high possibility of fabrication of over 1m size mirrors with surface accuracy of 1μm. Feasibility of CFRP mirrors for low temperature applications was examined for JASMINE project as an example. Stability of surface accuracy of CFRP mirrors against temperature and moisture was discussed.

Multifunctional Nanostructures with Controllable Band Gap Giving Highly Stable Infrared Emissivity for Smart Thermal Management

“…Figure a shows the thermo-optical characteristics of pristine CFRP (α S = 0.92, ε IR = 0.87), which is commonly used in satellites and advanced applications ,− (Figure b). However, it is vulnerable to degradation when it is externally exposed to the space environment. − Also, its thermo-optical properties cause the buildup of heat.…”

“…Thermal control is essential for spacecraft systems, in order to maintain the temperature of the spacecraft within a narrow range of operating temperatures during the operational lifetime. , The design of thermal control systems (TCSs) on satellites is dictated by the extreme conditions of the harsh environment in space. Large temperature differentials across mission payloads can exert dimensional changes that result in mechanical stresses, which must be mitigated, to avoid structural distortions and ensure mission success. − Without TCSs, these dimensional changes can result in misalignment of scientific instruments: i.e., optical components that are required to observe deep space and discover or monitor planets, as demonstrated recently. − The spacecraft temperature is maintained by means of a delicate balance among external fluxes, emitted radiation, and heat that is produced internally (Figure a). State-of-the-art TCSs include passive methods such as thin foils, multilayer insulation (MLI), sun shields, etc.…”

Radiation and electrostatic resistance for ultra-stable polymer composites reinforced with carbon fibers

“…For many space missions, highly stable, lightweight, and functional structures are essential to support precision apertures and finely calibrated instruments on satellites (1)(2)(3)(4). Stable structures, such as optical benches, telescope tubes, parabolic reflectors, rovers, and lander structures, are required for precision optics, radar, and scientific instruments for various deep-space, Earth, Observation, Navigation and Science (ENS), and exploration missions (5)(6)(7)(8)(9)(10)(11). It is imperative that these structural components maintain the highest performance under extreme test, launch, and space conditions to ensure mission viability (12)(13)(14).…”

Increasing the robustness and crack resistivity of high-performance carbon fiber composites for space applications

“…In addition, superlattice materials have been found useful for a broad range of engineering applications ( Zhang et al., 2018 ; Tsu, 2010 ). For example, superlattices consisting of thin layers of DLC can be used to increase the mobility of charge carriers, varying the optical band gap (∼1.5–5 eV) ( Silva et al., 1994 ; McIntosh et al., 2016 ), for instruments and high-frequency devices ( Utsunomiya et al., 2013 ; Bhattacharyya et al., 2006 ; Dong et al., 2019 ; Srinivasan et al., 2007 ; Gurnett et al., 1995 ). However, these materials incur high intrinsic stresses, which make them vulnerable to mechanical failure by cracking or flaking ( Abadias et al., 2018 ; Ali et al., 2015 ; Khanna, 2010 ).…”