NASA Selects Tethers Unlimited for Four Small Business Awards
Tethers Unlimited (TUI) will being developing a small satellite capable of growing itself in orbit and a metal press and milling system capable of creating precision parts in microgravity with the help of NASA funding.
The projects were among four TUI proposals the space agency selected under its Small Business Innovation Research (SBIR) Phase I program. The contracts are worth up to $125,000 apiece over six months.
The selected proposals include:
- MakerSat
- Metal Advanced Manufacturing Bot-Assisted Assembly (MAMBA) Process
- COBRA-Bee Carpal-Wrist Gimbal for Astrobee
- The Automated X-Link for Orbital Networking (AXON) Connector
The MakerSat proposal involves the development of “‘constructable’ technologies, that use in-space manufacturing technologies to enable SmallSats to ‘grow’ significantly larger structures. A SmallSat that, once on orbit, can increase its size from one to two orders of magnitude provides a transformative option to formation flying or deployable structures.
“‘MakerSat’ is a low-cost system intended to validate the Constructable SmallSat platform and enable nanosat-class systems to perform missions such as single-pass interferometric SAR, long-baseline radio astronomy, and infrared astronomy,” the proposal adds.
According to the proposal, TUI’s Metal Advanced Manufacturing Bot-Assisted Assembly (MAMBA) Process is
a robotically managed metal press and milling system used to create precision parts on orbit. This manufacturing process provides an alternative to 3D printing metals in space, which is difficult due to space environment or print quality issues.
Instead, the MAMBA-Process relies on an ingot forming technology to create a metal ingot. This ingot can then be milled and machined to form a precision part using a standard CNC milling technique.
In order to minimize astronaut time and exposure to the process, the MAMBA-Process will be outfitted with a robotic assistant, using robotic assistance to remove the ingot from the press, to place the ingot in the mill, and to perform tool changes on the mill.
TUI’s COBRA-Bee Carpal-Wrist Gimbal is a payload for the Astrobee free flying robot on the International Space Station. COBRA-Bee will “satisfy Astrobee mission needs for a lightweight, integrated end-effector/tool/sensor positioning and pointing system,” according to the proposal.

Astrobee P4’s functional features and those that will collect and feed operational data to ultimately assist astronauts in performing routine tasks. (Credit: NASA)
“COBRA-Bee will support target acquisition and tracking experiments for high performance optical communication. It can also support sensors which have limited field-of-view, such as cameras, as well as sensors/end-effectors requiring high pointing accuracy and/or independence from spacecraft attitude control,” the proposal states.
The Automated X-Link for Orbital Networking (AXON) Connector is designed to allow spacecraft components to be connected in space autonomously.
“The AXON connector will be a reversible module-to-module connector that minimizes mass and complexity while maximizing assembled stiffness, strength, power transfer, and data communications,” the proposal states. “The development of the AXON connector will leverage TUI’s existing programs and place emphasize automated robotic mating and de-mating.”
Summaries of the selected proposals follow.
Proposal Title: MakerSat
Subtopic Title: Small Spacecraft Structures, Mechanisms, and Manufacturing
Small Business Concern
Tethers Unlimited, Inc.
Bothell, WA
Principal Investigator/Project Manager
Dr. Blaine Levedahl
Estimated Technology Readiness Level (TRL) at beginning and end of contract:
Begin: 3
End: 4
Technical Abstract
Small satellite platforms such as CubeSats and nanosats are providing opportunities for NASA, DoD, ad commercial ventures to perform missions at lower cost and improved return-on-investment. There is a growing desire to enable SmallSats to perform “Long Baseline” and “Spatially Diverse” observation, measurement and collection missions.
Traditionally, these types of missions would be performed using formation flying or using large, costly satellites equipped with complex deployable structures. For many sensing modalities, fundamental physics demands large apertures or long baselines to achieve the high resolution, sensitivity, and throughput required for these missions. Reliance upon fixed and deployable aperture/mast technologies prevents small satellites from matching traditional large satellite platforms in terms of performance.
The proposed “MakerSat Demonstration Mission” effort will develop a third alternative that will enable small satellite platforms to perform his class of missions: “Constructable” technologies, that use in-space manufacturing technologies to enable SmallSats to “grow” significantly larger structures. A SmallSat that, once on orbit, can increase its size from one to two orders of magnitude provides a transformative option to formation flying or deployable structures.
“MakerSat” is a low-cost system intended to validate the Constructable SmallSat platform and enable nanosat-class systems to perform missions such as single-pass interferometric SAR, long-baseline radio astronomy, and infrared astronomy.
During the Phase I effort, TUI will develop the Requirements, ConOps and Architecture for the demonstration mission. During the Phase II effort, TUI will develop an EM unit suitable for demonstration and testing Trusselator mission technology. During the Phase III effort, TUI will integrate a FM version of the Trusselator demonstration technology into an appropriately sized SmallSat Bus and fly the MakerSat Demonstration Mission.
Potential NASA Commercial Applications
While SmallSats have the benefit of small size and mass, making them generally easier and cheaper to launch, fundamental physics demands large apertures and large baselines to achieve high performance in many sensing modalities. The MakerSat technology will enable cost-effective small satellite platforms to conduct these high-performance missions, including long-baseline interferometric SAR, interferometric astronomy, and geolocation. The MakerSat demonstration will establish the flight heritage necessary for in-space manufacturing technologies to be adopted into the critical path for NASA’s scientific and exploration missions.
Potential Non-NASA Commercial Applications
The MakerSat technology will enable commercial SAR ventures such as Capella Space to dramatically increase the performance of their SAR smallsats. It will enable DoD programs to use small satellite platforms to perform multi-ball interferometric geolocation of GPS jammers and bi-static radar systems for EO missions. The MakerSat demonstration will also establish flight heritage for the In-Space Manufacturing technology which is critical to the demonstration of the Trusselator on SSL’s Dragonfly mission and the DARPA OrbWeaver program.
Technology Taxonomy Mapping
- Composites
- In Situ Manufacturing
- Structure
Proposal Title: Metal Advanced Manufacturing Bot-Assisted Assembly (MAMBA) Process
Subtopic Title: In-Space Manufacturing of Precision Parts
Small Business Concern
Tethers Unlimited, Inc.
Bothell, WA
Principal Investigator/Project Manager
Dr. Rachel Muhlbauer
Estimated Technology Readiness Level (TRL) at beginning and end of contract:
Begin: 2
End: 3
Technical Abstract
Tethers Unlimited, Inc. (TUI) proposes to develop the Metal Advanced Manufacturing Bot-Assisted Assembly (MAMBA) Process, a robotically managed metal press and milling system used to create precision parts on orbit.
This manufacturing process provides an alternative to 3D printing metals in space, which is difficult due to space environment or print quality issues. Instead, the MAMBA-Process relies on an ingot forming technology to create a metal ingot. This ingot can then be milled and machined to form a precision part using a standard CNC milling technique.
In order to minimize astronaut time and exposure to the process, the MAMBA-Process will be outfitted with a robotic assistant, using robotic assistance to remove the ingot from the press, to place the ingot in the mill, and to perform tool changes on the mill.
The MAMBA effort will also develop a novel process for management and recycling of metal chips in a microgravity environment. Testing of the process technologies will lead to a lab demonstration of ingot formation and milling in the Phase I effort, maturing the MAMBA Process to TRL-3. In the Phase II effort, a full scale engineering unit will be built and tested to begin validating this technology for flight.
Potential NASA Commercial Applications
The MAMBA-Process will support long-duration manned missions such as Manned Mars Missions and the ISS by enabling manufacture of precision metal parts on-orbit as needed. Rather than fly a storage room of potential spare parts, the MAMBA-Process can be used to make these components when a need arises, limiting the initial launch volume.
In addition, the acceptance of used parts into the Positrusion-Press sub-technology allows for the recycling of used or failed parts, minimizes stored waste, and enables a closed loop ecosystem for metal fabrication. The ability to re-use mass taken on mission, dependent on the mission stage, will greatly increase capability per budgeted mass. In addition, the MAMBA-Process will enable the flexibility to replace critical components when resupply is impossible or improbable.
Potential Non-NASA Commercial Applications
The MAMBA-Process technologies can support commercial spaceflight companies with a focus on manned space travel by enabling in-space manufacture of precision metal parts. Its technologies will be critical to TUI’s OrbWeaver project to enable in-space manufacturing of large phased array antennas. Additionally, the MAMBA process will have utility aboard submarines and other remote facilities where resupply is limited.
Technology Taxonomy Mapping
- In Situ Manufacturing
- Metallics
Proposal Title: COBRA-Bee Carpal-Wrist Gimbal for Astrobee
Subtopic Title: Payload Technologies for Free-Flying Robots
Small Business Concern
Tethers Unlimited, Inc.
Bothell, WA
Principal Investigator/Project Manager
Dr. Nathan Britton
Estimated Technology Readiness Level (TRL) at beginning and end of contract:
Begin: 3
End: 4
Technical Abstract
TUI proposes to develop a carpal-wrist gimbal payload for the Astrobee free-flier, called “COBRA-Bee” to satisfy Astrobee mission needs for a lightweight, integrated end-effector/tool/sensor positioning and pointing system.
The COBRA-Bee is an evolution of TUI’s high-TRL, 3-DOF COBRA gimbal that will provide Astrobee end-effectors with the workspace dexterity of a full robotic manipulator (6-DOF via Astrobee fan system + 3-DOF via COBRA-Bee).
COBRA-Bee will support target acquisition and tracking experiments for high performance optical communication. It can also support sensors which have limited field-of-view, such as cameras, as well as sensors/end-effectors requiring high pointing accuracy and/or independence from spacecraft attitude control.
The 3-DOF (azimuth, elevation, and extension) of COBRA-Bee will support Astrobee experiments with pushing operations for fanless microgravity mobility. COBRA-Bee will provide this precise multi-purpose pointing and positioning capability in a small-scale tightly integrated COTS product, with an interface to support third-party sensors, end-effectors, and tools.
The Phase I effort will define requirements for a detailed design, based upon a crew safety analysis and a survey of candidate Astrobee end-effectors. A demonstration will be performed with existing COBRA hardware, maturing the COBRA-Bee TRL to 4. The Phase II effort will develop, test, and deliver an engineering unit and control software.
Potential NASA Commercial Applications
COBRA-Bee delivers benefit to NASA’s human spaceflight and ISS operations by reducing the need for astronaut time to perform recording and documentation of spacecraft experiments and mission operations. Astronaut time is a finite, highly valuable resource, and reducing dependency on it increases NASA’s mission capabilities and cost efficiency.
NASA’s ISS and future long-duration human spaceflight missions (ie Journey to Mars) represent direct applications for COBRA-Bee. In addition, guest scientist developers of end-effector technology will have access to an API for the COBRA-Bee payload to assist in the development of end-effector functions such as target deceleration, vibration mitigation, and angular-momentum management in their applications. This will enable them to focus on the specifics of their various payloads, some of which may be graduated to nominal Astrobee service operations. Additionally a power savings may be achieved with less reliance on Astrobee attitude control and mobility subsystems.
Potential Non-NASA Commercial Applications
The COBRA-Bee payload will enable the Astrobee system to support evolving in-space manufacturing and assembly capabilities by providing cost-effective robotic monitoring capabilities. Additionally, it will enable Astrobee to support automated or teleoperated manipulation or monitoring of commercial experiments performed on the ISS through NanoRacks’ NanoLab system and on Axiom Space’s commercial ISS module.
Technology Taxonomy Mapping
- Actuators & Motors
- Machines/Mechanical Subsystems
- Robotics (see also Control & Monitoring; Sensors)
- Tools/EVA Tools
Proposal Title: The Automated X-Link for Orbital Networking (AXON) Connector
Subtopic Title: In-Space Structural Assembly and Construction
Small Business Concern
Tethers Unlimited, Inc.
Bothell, WA
Principal Investigator/Project Manager
Dr. Blaine Levedahl
Estimated Technology Readiness Level (TRL) at beginning and end of contract:
Begin: 2
End: 3
Technical Abstract
NASA has identified the need for a joining technologies to support the ability to connect spacecraft components autonomously in-space. The joining technology should be modular, reversible, have an open-architecture, and allow “plug-and-play” functionality for maximum flexibility and utilize simple approaches amenable to robotic assembly and disassembly.
TUI has been working on structural truss joining (Class 1 joints) and robotic connection approaches through separate efforts and has several ongoing and future efforts that will require in-space joining of modular systems (Class 2 joints).
TUI proposes to develop and demonstrate an open-architecture Class 2 joining solution called the Automated X-Linked for Orbital Networking (AXON) connector. The AXON connector will be a reversible module-to-module connector that minimizes mass and complexity while maximizing assembled stiffness, strength, power transfer, and data communications. The development of the AXON connector will leverage TUI’s existing programs and place emphasize automated robotic mating and de-mating.
In the Phase I effort, we will identify a complete set of requirements, develop a concept design, fabricate the concept using TUI’s 3D printing and rapid prototyping capabilities, and test the AXON connector using TUI’s Baxter robot. In the Phase II effort, TUI will mature the Phase I design and perform reliability testing.
Potential NASA Commercial Applications
The AXON connector will facilitate in-space assembly of satellites, exploration probes, and habitats for robotic and manned missions to the moon, Mars, and deep space destinations. Specific NASA Technology Roadmap topic areas that can benefit from the AXON connector include very large solar array structure (12.2.1.4), reusable modular components (12.2.5.4), deployables, docking, and interfaces (12.3.1), power management and distribution (3.3), structures and antennas for observatories (8.2.2), and systems engineering for robotic and autonomous systems (4.7).
Potential Non-NASA Commercial Applications
Beyond spacecraft applications, the advancements the AXON connector enables for in-space structural construction technologies will be directly applicable to constructing large structures in-space and enabling new missions in both the commercial space industry and the DoD. TUI is already developing complementary in-space manufacturing technologies with both the DoD and commercial partners.
Technology Taxonomy Mapping
- Fasteners/Decouplers
- In Situ Manufacturing
- Machines/Mechanical Subsystems
- Passive Systems
- Robotics (see also Control & Monitoring; Sensors)
- Spacecraft Design, Construction, Testing, & Performance (see also Engineering; Testing & Evaluation)
- Structures
- Waveguides/Optical Fiber (see also Optics)
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