RoboCrane: a system for providing a power and a communication link between lunar surface and lunar caves for exploring robots

Lava caves are the result of a geological process related to the cooling of basaltic lava flows. On the Moon, this process may lead to caves several kilometers long and diameters of hundreds of meters. Access to lava tubes can be granted through skylights, a vertical pit between the lava tube and the lunar surface. This represents an outstanding opportunity for long-term missions, for future permanent human settlements, and for accessing pristine samples of lava, secondary minerals and volatiles. Given this, the ESA launched a campaign through the Open Space Innovation Platform calling for ideas that would tackle the many challenges of exploring lava pits. Five projects, including Robocrane, were selected. Solar light and direct line of sight (for communications) with the lunar surface are not available inside lava tubes. This is a problem for any robot (or swarm of robots) exploring the lava tubes. Robocrane tackles both problems by deploying an element (called the Charging head, or CH) at the bottom of the skylight by means of a crane. This CH behaves as a battery charger and a communication relay for the exploring robots. The required energy is extracted from the crane’s solar panel (on the surface) and driven to the bottom of the skylight through an electrical wire running in parallel to the crane hoisting wire. Using a crane allows the system to deal with unstable terrain around the skylight rim and protect the wires from abrasion from the rocky surface and the pit rim. The charger in the CH is wireless so that the charging process can begin as soon as any of the robots get close enough to the CH. This avoids complex and time-consuming docking operations, aggravated by the skylight floor orography. The crane infrastructure can also be used to deploy the exploring robots inside the pit, reducing their design constraints and mass budget, as the robots do not need to implement their own self-deployment system. Finally, RoboCrane includes all the sensors and actuators for remote operation from a ground station. RoboCrane has been designed in a parametric tool so it can be dynamically and rapidly adjusted to input-variable changes, such as the number of exploring robots, their electrical characteristics, and crane reach, etc.Agencia Estatal de Investigación | Ref. RTI2018-099682-A-I0

A photo‐thermoelectric twist to wireless energy transfer: radial flexible thermoelectric device powered by a high‐power laser beam

Systems for wireless energy transmission (WET) are gaining prominence nowadays. This work presents a WET system based on the photo-thermoelectric effect. With an incident laser beam at λ = 1450 nm, a temperature gradient is generated in the radial flexible thermoelectric (TE) device, with a carbon-based light collector in its center to enhance the photoheating. The three-part prototype presents a unique approach by using a radial TE device with one simple manufacturing process - screen-printing. A TE ink with a polymeric matrix of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate and doped-Poly(vinyl alcohol) with Sb-Bi-Te microparticles is developed (S∽33 µVK−1 and s∽10.31 Sm−1), presenting mechanical and electrical stability. Regarding the device, a full electrical analysis is performed, and the influence of the light collector is investigated using thermal tests, spectrophotometry, and numerical simulations. A maximum output voltage (Vout) of ∽16 mV and maximum power density of ∽25 µWm−2 are achieved with Plaser = 2 W. Moreover, the device's viability under extreme conditions is explored. At T∽180 K, a 25% increase in Vout compared to room-temperature conditions is achieved, and at low pressures (∽10‒6 Torr), an increase of 230% is obtained. Overall, this prototype allows the supply of energy at long distances and remote places, especially for space exploration.Federación Española de Enfermedades Raras | Ref. UID/NAN/50024/2019Federación Española de Enfermedades Raras | Ref. NORTE‐01‐0145‐FEDER022096Fundação para a Ciência e a Tecnologia | Ref. UIDB/04968/2020Fundação para a Ciência e a Tecnologia | Ref. UIDP/04968/202