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Page 14 of 35 Kulkarni et al. Soft Sci. 2025, 5, 12 https://dx.doi.org/10.20517/ss.2023.51

transfer. Therefore, space robots must be able to transfer heat through conduction or radiation between
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spacecraft and the surrounding environment or be thermally insulated to regulate device temperature .
Robots in space may be exposed to high-energy particles and radiation because of the absence of a
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geomagnetic field . This radiation can result in disturbances in electrical equipment including
semiconductor components . Durability and redundancy in design are important considerations for
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robots as the ability to fix or replace components is non-trivia, and thus self-healing properties of soft
devices enable the longer-term service in unmanned environments .
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Soft actuators for space environments
The tasks a robot may need to perform in space range from assembly to locomotion to sampling, dictating
the actuation mechanism used in design [Figure 7A]. Deformability, impact-bearing capability, and
resistance to brittle failure are important features needed to negotiate unstructured space environments .
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Compliant soft microsatellite grippers can conform to capture irregular space debris . Areas with large
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amounts of cosmic radiation may cause materials to become rigid and brittle . Soft robots must be able to
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operate in extreme temperatures in space, such as regions without sunlight that can reach temperatures in
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the range of -200 to -150 °C . Also, the surface temperature of spacecraft in direct sunlight ranges from 97
to 127 °C. Therefore, using materials that can maintain their properties and characteristics over a wide
range of temperatures is important for soft robotic applications in space. For instance, temperature-resistant
elastomers such as silicone can be used for high-temperature applications . Ogliani et al. display the
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material properties of silicone elastomers with different crosslinking densities through thermogravimetric
analysis by testing these elastomers up to 700 °C in a nitrogen atmosphere . This study depicts how
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removing the sol fraction of PDMS increases the thermal stability of silicone elastomers. Porte et al. describe
how elastomers that are commonly used in soft robotics including EcoFlex 00-30, Dragon Skin 10, Smooth-
Sil 950, and Sylgard 184, were tested under temperatures ranging from -40 to 140 °C . The results of the
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test depict how generally as the temperature rises, the stiffness of the material also increases . While some
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elastomeric materials have material properties that depend significantly on temperature variances, materials
such as fiber materials, including Kevlar, and organic materials, such as polyimide and Teflon, have high-
temperature tolerances .
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Fluidic actuation mechanisms can be used in soft robotic actuators for space applications as they are
adaptable and may generate high output forces with low energy input . Zhang et al. propose a soft robotic
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gripper with pneumatic actuators designed for low air pressure . This actuator is fabricated from carbon
fiber reinforced polymer laminates which allows it to be stable in two actuation states. The gripper also has a
low total energy consumption (~1.85 J) for every grasping motion. Palmieri et al. propose a deployable soft
arm made of pneumatic inflatable links that can be stored in a small package for reduced weight and volume
during shipping [Figure 7B] .
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Solar-driven soft robots can be used for space applications for their efficient energy systems. Mirvakili et al.
developed a solar-driven soft robot consisting of a pressure chamber containing a low boiling point liquid
[Figure 7C] . One end serves as a heat sink while the other is connected to a silicone-based soft robot.
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Once exposed to white light, a solar absorber film increases the liquid temperature which increases pressure
output and forces actuation.

Electrically driven soft actuators can also be used for space applications as they can be lightweight, easily
transportable, and durable . To verify if these actuators will perform well in low-pressure environments,
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DEAs, composed of silicone rubber sandwiched between two carbon black layers, were deflection tested.
Actuator displacement was tested under different pressure conditions by applying a constant voltage to the