DARPA: Building Space Elevators, Space Nets, and other Large Bio-Mechanical Space Structures
bioinspired space structure — Grok via Astrobiology.com
Given recent advances in metabolic engineering for rapid growth, extremophiles with novel properties, biological self-assembly properties of tunable materials, and emergent mechanical design principles of biological systems, DARPA is interested in exploring the feasibility of “growing” biological structures of unprecedented size in microgravity.
Rapid, controlled, directional growth to create very large (500+ meter length) useful space structures would disrupt the current state-of-the-art and position biology as a complimentary component of the in-space assembly infrastructure.
Some examples of structures that could be biologically manufactured and assembled, but that may be infeasible to produce traditionally, include tethers for a space elevator, grid-nets for orbital debris remediation, kilometer-scale interferometers for radio science, new self- assembled wings of a commercial space station for hosting additional payloads, or on-demand production of patch materials to adhere and repair micrometeorite damage.
To address major barriers to the safe creation of 500-meter-long bio-mechanical structures in space, the Defense Advanced Research Projects Agency (DARPA) Biological Technologies Office (BTO) is requesting information related to methods and new technical insights by which to create and functionalize large, self-assembled, mechanically stable biological growths in space that have structural rigidity (stiffness/strength).
A hybrid workshop is planned in the San Francisco Bay Area to discuss credible responses and assess if there are dramatically new technical insights that may be worth investment by DARPA.
BACKGROUND AND VALUE PROPOSITION
The specific advantage of large biological structures in microgravity is that they can be grown in space, i.e., the value proposition lies in the potential for drastic reduction in the amount of upmass or volume launched from Earth. There are numerous examples of exploiting the self-assembly and rapid growth properties inherent to engineered biology.
However, purely biological growth mechanisms are unlikely to be successful on their own. Creating useful structures capable of structural rigidity (stiffness/strength/load bearing), while growing in microgravity conditions, requires a close partnership between mechanical, structural, and biological engineering.
A relevant analogy is that of a tent. Given the structural material of the tent poles, biological growth mechanisms are envisioned to be the “cover” of the tent. The tent can be shaped a particular way by the underlying poles, and when embedded with appropriate electronics, perform a given function. The key value proposition for spaceflight would be a favorable ratio between the mass and/or volume of traditional (non-biological) materials versus in-situ grown biological materials. Maximizing this value proposition requires co-engineering between the structural/mechanical and the biological to arrive at useful structures.
A key unknown in creating such bio-mechanical structures in space is how the structure would be assembled. Feedstock must be provided (and relocated if necessary) to the growing edge, or to the area from which biological materials are being extruded. If aerobic organisms or mechanisms are required (grown in space and then desiccated by exposure to vacuum when growth is complete), the methods and support equipment required to preserve key aerobic variables (e.g., atmosphere, pressure, temperature) must be part of the biomechanical assembly system design. Anaerobic organisms or mechanisms may allow for less support hardware but may require other controls to support continued growth in the space environment (e.g. pressure, temperature, humidity).
Finally, the envisioned large-scale biomechanical structures must be directional in their growth. Depending on the use case envisioned, they may require the ability to embed or integrate electronics or structural materials between/around grown biological “filler”.
REQUESTED INFORMATION
This RFI seeks responses that address development pathways for very large (defined as 500 meters or greater in primary dimension) bio-mechanical space structures. Responses should directly address the following five items:
Use case. Elucidate the “use case” for the envisioned large bio-mechanical space structures. Some examples are: space elevator tether from geostationary to low-Earth orbit, grid-nets for orbital debris remediation, self-assembled space stations for payload hosting.
Co-engineering. Insights from both the structural/mechanical point of view, and the biological engineering point of view, to arrive at the envisioned useful structure. This should include information on the specific biological material(s)[1 Examples of biological materials or building blocks may include, but are not limited to, thread-like hyphae such as fungal mycelia, graphene aerogels or other biocompatible materials, filamentous protein-based fibers like those found in hagfish slime, etc.] envisioned for 500-meter scale growth, and the method by which to control its directionality.
Feedstock. How feedstock will be provided (and relocated if necessary) to the continuously growing edge. Clearly identify if the leading edge is the growth edge, or if the leading edge is extruded away from the growth region, and explain rationale.
Value proposition. Order of magnitude estimation of the mass ratio between traditional (non-biological) materials and biological materials, with a strong preference for as little traditional material as feasible.
a. The ratio of “launched from Earth” biological growth materials, with respect to the biological mass of the completed structure, is of particular interest.
b. The ratio of “launched from Earth” system volume, with respect to the volume of the completed structure, is of particular interest.
c. Unless specifically biological in nature (e.g. bio-concrete, living bricks), any assembly system would count against traditional materials when calculating ratios.
Scope of Proof-of-concept experiment. Ground-based proofs of concept that address factors specific to the space environment and go from inception to notional finished structure. If executed, this experiment would prove the concept for an in-space use case.
If the concept can only be proven in microgravity2, please explain rationale. Responses that include any of the following information are particularly helpful to scope a potential future DARPA investment:
Timescale for growth as a function of dimension,
Proof of feasibility, such as existing modeling, simulation, or empirical data,
New insights into the emergent mechanics of large-scale biological structures to predict and engineer spatial/temporal patterns of dynamic bio-structures,
Space-specific issues such as survivability, radiation tolerance or durability,
Design details for mass and volume estimates used to calculate the value proposition.
Large Bio-Mechanical Space Structures, DARPA – Full document
Request for Information (RFI) – Large bio-mechanical space structures
DARPA-SN-25-51
Building Space Elevators, Space Nets, and other Large Bio-Mechanical Space Structures
Responses Deadline: March 27, 2025, 4:00 PM ET
POC: Dr. Michael Nayak, Program Manager, DARPA
E-mail: [email protected]
URL: https://www.darpa.mil/research#research-opportunities
Astrobiology, SynBio, Nanotechnology, Microgravity,