Type | Private |
---|---|
Industry | Aerospace |
Founded | 1994 [1] |
Founder | Robert L. Forward, Robert P. Hoyt |
Headquarters | , United States |
Key people | Robert P. Hoyt [1] |
Products | space tethers, orbital robotic assembly and fabrication technologies |
Number of employees | ~50 (2019) [3] |
Website | www |
Tethers Unlimited, Inc. (TUI) is an American private aerospace company headquartered near Seattle, Washington, which performs research and development of new products and technologies for space, sea, and air.
Founded in 1994 by Robert P. Hoyt and Robert L. Forward, Tethers Unlimited began developing products based on space tether technologies, including concepts for removal of space debris [4] and momentum exchange tethers for launching payloads into higher orbits. TUI has since broadened its suite of technologies to include power, propulsion, actuation, and communications systems for small satellites, robotic technologies for on-orbit fabrication and assembly, optical fiber winding and deployment, software defined radio communications, and 3D printed radiation shielding.
In 2007, in collaboration with Stanford University, the company launched the Multi-Application Survivable Tether (MAST) experiment to test the survivability of tethers in space. [5] [6] [7] In 2016 it was reported by SpaceNews and Yahoo that the company's subdivision Firmamentum signed a deal with SSL to fly its in-space manufacturing technologies on SSL's Dragonfly program which is funded by NASA's Tipping point initiative. [8] [9]
In December 2018 it was reported that Tethers Unlimited delivered a Refabricator to the ISS that accepts plastic material and converts it into high-quality 3D printer filament, [10] for the mission duration of October 2018 to April 2019. [11]
According to TUI's website, Firmamentum is currently working on building the 'Spiderfab' technology to "enable on-orbit fabrication of large spacecraft components such as antennas, solar panels, trusses, and other multifunctional structures." [12] Through this technology a spacecraft would be able to build structures far greater than itself in orbit. [13] [14]
On May 6, 2020 it was announced that Amergint Technologies acquired Tethers Unlimited [15]
SSL, formerly Space Systems/Loral, LLC (SS/L), of Palo Alto, California, is a wholly owned manufacturing subsidiary of Maxar Technologies.
A momentum exchange tether is a kind of space tether that could theoretically be used as a launch system, or to change spacecraft orbits. Momentum exchange tethers create a controlled force on the end-masses of the system due to the pseudo-force known as centrifugal force. While the tether system rotates, the objects on either end of the tether will experience continuous acceleration; the magnitude of the acceleration depends on the length of the tether and the rotation rate. Momentum exchange occurs when an end body is released during the rotation. The transfer of momentum to the released object will cause the rotating tether to lose energy, and thus lose velocity and altitude. However, using electrodynamic tether thrusting, or ion propulsion the system can then re-boost itself with little or no expenditure of consumable reaction mass.
Space manufacturing is the production of tangible goods beyond Earth. Since most production capabilities are limited to low Earth orbit, the term in-orbit manufacturing is also frequently used.
Gravity-gradient stabilization or tidal stabilization is a passive method of stabilizing artificial satellites or space tethers in a fixed orientation using only the mass distribution of the orbited body and the gravitational field. The main advantage over using active stabilization with propellants, gyroscopes or reaction wheels is the low use of power and resources. It can also reduce or prevent the risk of propellant contamination of sensitive components.
The NASA Institute for Advanced Concepts (NIAC) is a NASA program for development of far reaching, long term advanced concepts by "creating breakthroughs, radically better or entirely new aerospace concepts". The program operated under the name NASA Institute for Advanced Concepts from 1998 until 2007 (managed by the Universities Space Research Association on behalf of NASA), and was reestablished in 2011 under the name NASA Innovative Advanced Concepts and continues to the present. The NIAC program funds work on revolutionary aeronautics and space concepts that can dramatically impact how NASA develops and conducts its missions.
The Multi-Application Survivable Tether (MAST) experiment was an in-space investigation designed to use CubeSat spacecraft connected by tethers to better understand the survivability of tethers in space. It was launched as a secondary payload on a Dnepr rocket on 17 April 2007 into a 98°, 647 x 782 km orbit. The MAST payload incorporated three picosatellites, named "Ralph," "Ted," and "Gadget," which were intended to separate and deploy a 1 km (0.62 mi) tether. The experiment hardware was designed under a NASA Small Business Technology Transfer (STTR) collaboration between Tethers Unlimited, Inc. (TUI) and Stanford University, with TUI developing the tether, tether deployer, tether inspection subsystem, satellite avionics, and software, and Stanford students developing the satellite structures and assisting with the avionics design.
Non-rocket spacelaunch refers to theoretical concepts for launch into space where much of the speed and altitude needed to achieve orbit is provided by a propulsion technique that is not subject to the limits of the rocket equation. Although all space launches to date have been rockets, a number of alternatives to rockets have been proposed. In some systems, such as a combination launch system, skyhook, rocket sled launch, rockoon, or air launch, a portion of the total delta-v may be provided, either directly or indirectly, by using rocket propulsion.
Robert P. Hoyt is a physicist and engineer who is known for his work developing the SpiderFab architecture for in-space additive manufacture of spacecraft as well as for his invention of the Hoytether. He also originated the MXER Tether concept, which combines momentum-exchange techniques with electrodynamic reboost propulsion to enable a bolo tether system to serve as a fully reusable in-space upper stage for boosting many payloads from LEO to GEO or lunar trajectories. He also has done work and collaborated with the late Robert L. Forward on electrodynamic space tethers for use for deorbiting space junk and interplanetary transport. He was one of the authors of a paper on using tethers for cis-lunar transportation. The Cooper Hewitt Smithsonian Design Museum included a Hoytether designed and fabricated by Hoyt in an exhibition on high-tech textiles.
A number of space tethers have been deployed in space missions. Tether satellites can be used for various purposes including research into tether propulsion, tidal stabilisation and orbital plasma dynamics.
Space tethers are long cables which can be used for propulsion, momentum exchange, stabilization and attitude control, or maintaining the relative positions of the components of a large dispersed satellite/spacecraft sensor system. Depending on the mission objectives and altitude, spaceflight using this form of spacecraft propulsion is theorized to be significantly less expensive than spaceflight using rocket engines.
The NASA Launch Services Program (LSP) is responsible for procurement of launch services for NASA uncrewed missions and oversight of launch integration and launch preparation activity, providing added quality and mission assurance to meet program objectives. LSP operates under the NASA Space Operations Mission Directorate (SOMD).
Busek Co. Inc. is an American spacecraft propulsion company that builds thrusters, electronics, and various systems for spacecraft.
Space Tethered Autonomous Robotic Satellite II or STARS-II, was a nanosatellite built by Japan's Kagawa University to test an electrodynamic tether in low Earth orbit, a follow-on to the STARS mission.
Made In Space, Inc. (MIS) is an American company specializing in the engineering and manufacturing of three-dimensional printers for use in microgravity. Headquartered in Jacksonville, Florida, Made In Space's 3D printer was the first manufacturing device used in space.
Psyche is a planned orbiter mission to explore the origin of planetary cores by studying the metallic asteroid of the same name. Lindy Elkins-Tanton of Arizona State University is the principal investigator who proposed this mission for NASA's Discovery Program. NASA's Jet Propulsion Laboratory (JPL) will manage the project.
Bi-sat Observations of the Lunar Atmosphere above Swirls (BOLAS) is a spacecraft mission concept that would orbit the Moon at very low altitude in order to study the lunar surface. The concept, currently under study by NASA, involves two small identical CubeSat satellites connected vertically above the lunar surface by a 25 km long tether. The mission goal would be to understand the hydrogen cycle on the Moon, dust weathering, and the formation of lunar swirls.
NASA's Pathfinder Technology Demonstrator (PTD) Project will test the operation of a variety of novel technologies on a type of nanosatellites known as CubeSats, providing significant enhancements to the performance of these versatile spacecraft. Each of the five planned PTD missions consist of a 6-unit (6U) CubeSat with expandable solar arrays.
CAPSTONE is a lunar orbiter that will test and verify the calculated orbital stability planned for the Lunar Gateway space station. The spacecraft is a 12-unit CubeSat that will also test a navigation system that will measure its position relative to NASA's Lunar Reconnaissance Orbiter (LRO) without relying on ground stations. It was launched on 28 June 2022, arrived in lunar orbit on 14 November 2022, and was scheduled to orbit for six months. On 18 May 2023, it completed its primary mission to orbit in the near-rectilinear halo orbit for six months, but will stay on this orbit, continuing to perform experiments during an enhanced mission phase.
The Power and Propulsion Element (PPE), previously known as the Asteroid Redirect Vehicle propulsion system, is a planned solar electric ion propulsion module being developed by Maxar Technologies for NASA. It is one of the major components of the Gateway. The PPE will allow access to the entire lunar surface and a wide range of lunar orbits and double as a space tug for visiting craft.