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Once China’s Tianwen-1 Mars probe arrived in a Mars orbit after a seven-month flight in the deep cold space environment, it would be urgently necessary to monitor its state and the surrounding environment. To address this issue, we developed a flexible deployable subsystem based on shape memory polymer composites (SMPC-FDS) with a large folding ratio, which incorporates a camera and two temperature telemetry points for monitoring the local state of the Mars orbiter and the deep space environment. Here, we report on the development, testing, and successful application of the SMPC-FDS. Before reaching its Mars remote-sensing orbit, the SMPC-FDS is designed to be in a folded state with high stiffness; after reaching orbit, it is in a deployed state with a large envelope. The transition from the folded state to the deployed state is achieved by electrically heating the shape memory polymer composites (SMPCs); during this process, the camera on the SMPC-FDS can capture the local state of the orbiter from multiple angles. Moreover, temperature telemetry points on the SMPC-FDS provide feedback on the environment temperature and the temperature change of the SMPCs during the energization process. By simulating a Mars on-orbit space environment, the engineering reliability of the SMPC-FDS was comprehensively verified in terms of the material properties, structural dynamic performance, and thermal vacuum deployment feasibility. Since the launch of Tianwen-1 on 23 July 2020, scientific data on the temperature environment around Tianwen-1 has been successfully acquired from the telemetry points on the SMPC-FDS, and the local state of the orbiter has been photographed in orbit, showing the national flag of China fixed on the orbiter.

Anchoring phosphotungstic acid (HPW) on insoluble inorganic fillers is a facile and effective approach to suppress its leakage in the proton exchange membrane. In this work, we introduced β-cyclodextrin (β-CD) on halloysite nanotubes (HNTs) with the aid of polydopamine coating to prepare water-insoluble β-CD-DHNTs, which was dispersed in the SPEEK matrix to anchor HPW. Both HPW and β-CD-DHNTs are well dispersed in the SPEEK matrix because of the hydrogen bonding complexation between [PW12O40]3- and β-CD. For the SPEEK/β-CD-DHNTs/HPW composite membranes, the proton conductivity increased with the increase of HPW content, reaching the maximum of ~120% increase relative to that of the SPEEK membrane. The HPW immobilized by the β-CD and polydopamine on the nanotubes could provide more active sites, resulting in the construction of more continuous proton transfer pathways. Therefore, as compared to the SPEEK membrane, lower activation energy for the proton transport was observed for the composite membrane, which also exhibited stable proton conductivity during the water immersion test for 30 days.

Phosphotungstic acid (HPW)-filled composite proton exchange membranes possess high proton conductivity under low relative humidity (RH). However, the leaching of HPW limits their wide application. Herein, we propose a novel approach for anchoring water soluble phosphotungstic acid (HPW) by polydopamine (PDA) coated graphene oxide and halloysite nanotubes (DGO and DHNTs) in order to construct hybrid three-dimensional proton transport networks in a sulfonated poly(ether ether ketone) (SPEEK) membrane. The introduction of PDA on the surfaces of the hybrid fillers could provide hydroxyl groups and secondary amine groups to anchor HPW, resulting in the uniform dispersion of HPW in the SPEEK matrix. The SPEEK/DGO/DHNTs/HPW (90/5/5/60) composite membrane exhibited higher water uptake and much better conductivity than the SPEEK membrane at low relative humidity. The best conductivity reached wass 0.062 S cm−1 for the composite membrane, which is quite stable during the water immersion test.

It is of great importance to improve the proton conductivity of proton exchange membranes by easy-handling and cost-efficient approaches. In this work, we incorporated a commercially obtained surfactant, sodium dodecyl benzene sulfonate (SDBS), into sulfonated poly(ether ether ketone) (SPEEK) through solution casting to prepare SPEEK/SDBS membranes. When no more than 10 wt % SDBS was added, the SDBS was well dissolved into the SPEEK matrix, and the activation energy for the proton transfer in the SPEEK/SDBS membranes was greatly reduced, leading to significant enhancement of the membrane proton conductivity. Compared with the SPEEK control membrane, the SPEEK/SDBS membrane with 10 wt % SDBS showed a 78% increase in proton conductivity, up from 0.051 S cm−1 to 0.091 S cm−1, while the water uptake increased from 38% to 62%. Moreover, the SPEEK/SDBS membrane exhibited constant proton conductivity under a long-term water immersion test.

Based on our previous successful material-level verification of a shape-memory polymer composite (SMPC) on the SJ-17 geostationary satellite on a geostationary orbit since November 2016, a structure-level smart solar array was developed in this study to further verify its overall performance on the SJ-18 geostationary satellite. The two-panel smart solar array based on shape-memory materials was designed and experimentally evaluated. The smart solar array consisted of two deployable solar panels, which were locked by one shape-memory alloy and two SMPC releasing mechanisms, and could be released by low shocking through electrical heating. The smart solar array was actuated and deployed using two groups of SMPC hinges. A series of tests was conducted to evaluate the main performance of the smart solar array. The tests included structural dynamics (folded state: sinusoidal sweep vibration, shocking, acceleration, and noise; and deployed state: mode, sinusoidal sweep vibration, and flexibility), thermal design, locking and releasing, and deployment. This smart solar array satisfied the design requirements, including the fundamental natural frequency in a folded state at 80 Hz, maximum the locking force at 2000 N. Based on the structure-level systematical evaluation, the SMPC shows prospect to be used in next-generation superlarge deployment structures. [ABSTRACT FROM AUTHOR]