Aranea Debris Interceptor – A Biomimetic Approach to Orbital Debris Mitigation​

In addressing the escalating challenge of orbital debris, it is imperative to note that as of 2022, Earth’s orbit contains over 34,000 debris objects larger than 10 cm, along with countless smaller fragments. Orbital debris from defunct satellites and collisions presents direct and imminent threats to 3,400 operational satellites that play crucial roles in global communication, meteorological predictions, navigation, and Earth observation. Beyond these tangible assets, human spaceflight, representative of the continuous drive of humankind for exploration and understanding, faces significant risk from these uncontrolled fragments. At the staggering velocities characteristic of orbital motion, even minute debris can critically compromise mission objectives and endanger human lives. A failure to mitigate debris growth risks satellite infrastructure loss and the onset of the Kessler Syndrome, which could make certain orbital zones too dangerous for operations.

Figure 1. ADI for orbital debris mitigation (a) ogre-faced spider; (b) forward capture of debris; (c) backward capture of debris; (d) self-deorbiting of ensnared debris.

The goal of this research is to develop the “Aranea Debris Interceptor” (ADI), a state-of-the-art spacecraft designed to address the escalating challenge of orbital ​​debris mitigation. Drawing inspiration from the prey-capturing tactics of the ogre-faced spider (Deinopis), presented in Fig. 1 (a), the ADI is equipped with six deployable tensegrity arms. Central to its operation is the in-space fabrication of a debris-capturing net, held taut by its flexible arms, reminiscent of the hunting stance of an ogre-faced spider (see Fig. 1 (b) and (c) for forward and backward captures, respectively). Upon detection of suitable debris, ADI envelops the target with its appropriately fabricated net, thereafter securely closing and fastening the net. As illustrated in Fig. 1 (d), an auxiliary feature is the attachment of a small drag sail to the ensnared debris, facilitating a self-deorbiting mechanism. Distinctively, the ADI boasts an expansive solar sail, allowing it to traverse between orbits, thus broadening its debris collection range.

​Deployable Tensegrity Arms

​The first task involves the design and prototyping of deployable tensegrity arms for the ADI. The proposed design utilizes two cable-driven clustered tensegrity structures (CTS) to build an eight-degrees-of-freedom robot arm, thereby facilitating a highly adaptable system, illustrated in Fig. 2. A tensegrity structure is a pin-jointed structure composed of isolated bars inside a net of cables. The CTS is a tensegrity structure with clustered cables, where the clustered cable is a group of adjacent individual cables combined into one continuous cable running over pulleys or through loops at the nodes of the structure. The utilization of CTS for the arm construction is intentional, prioritizing the low mass and high stiffness of the system — a critical consideration in spacecraft design. Moreover, the CTS design allows for effective folding and deployment utilizing a single motor to roll or release the clustered cables. The use of CTS not only reduces mechanical complexity but also aims to ensure reliability and longevity of the operational capabilities of the arms in the harsh environment of space.

Figure 2: Deployed and folded tensegrity arm.

In-space Fabrication of Debris-capturing Net

This task focuses on the development of a space-capable fabrication strategy for debris-capturing net, drawing inspiration from the web-weaving of an ogre-faced spider. As shown in Fig. 3 (a), the process starts with the deployment of radial lines, utilizing high-elasticity, strong cables previously wound on reels within the upper chassis of the ADI. These radial lines establish the structural basis of the net. As shown in Fig. 3 (b), four tensegrity arms of the ADI are employed to extend and stabilize the four corners of the net, anchoring it in space. Concurrently, two additional arms work together to lay down horizontal lines. These lines are engineered with a central, durable cable core, enveloped by thinner magnetic strands spiraled tightly around it, further improving its capability of securely wrapping orbital debris. The composition of the core line mirrors that of the radial lines, bestowing the net with superior flexibility and enhancing its capability to ensnare varying sizes of orbital debris effectively. At each intersection where the cables connect, space welding technology is utilized to secure the connections, ensuring the integrity and strength of the net structure.

Figure 3: Debris-capturing net: (a) topology design; (b) in-space fabrication

References

  1. Kazoleas, C., Mehta, K. and Yuan, S., 2022, October. Prototype Design and Manufacture of a Deployable Tensegrity Microrobot. In ASME International Mechanical Engineering Congress and Exposition (Vol. 86649, p. V02BT02A055). American Society of Mechanical Engineers. doi: 10.1115/IMECE2022-93929