Space tether

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Artist's conception of satellite with a tether Tether-satellite-NASA.jpg
Artist's conception of satellite with a tether

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. [1] 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.

Contents

Main techniques

Tether satellites might be used for various purposes, including research into tether propulsion, tidal stabilization and orbital plasma dynamics. Five main techniques for employing space tethers are in development: [2] [3]

Electrodynamic tethers

Electrodynamic tethers are primarily used for propulsion. These are conducting tethers that carry a current that can generate either thrust or drag from a planetary magnetic field, in much the same way as an electric motor does.

Momentum exchange tethers

These can be either rotating tethers, or non-rotating tethers, that capture an arriving spacecraft and then release it at a later time into a different orbit with a different velocity. Momentum exchange tethers can be used for orbital maneuvering, or as part of a planetary-surface-to-orbit / orbit-to-escape-velocity space transportation system.

Tethered formation flying

This is typically a non-conductive tether that accurately maintains a set distance between multiple space vehicles flying in formation.

Electric sail

A form of solar wind sail with electrically charged tethers that will be pushed by the momentum of solar wind ions.

Universal Orbital Support System

A concept for suspending an object from a tether orbiting in space.

Many uses for space tethers have been proposed, including deployment as space elevators, as skyhooks, and for doing propellant-free orbital transfers.

History

Konstantin Tsiolkovsky (1857–1935) once proposed a tower so tall that it reached into space, so that it would be held there by the rotation of Earth. However, at the time, there was no realistic way to build it.

In 1960, another Russian, Yuri Artsutanov, wrote in greater detail about the idea of a tensile cable to be deployed from a geosynchronous satellite, downwards towards the ground, and upwards away, keeping the cable balanced. [4] This is the space elevator idea, a type of synchronous tether that would rotate with the Earth. However, given the materials technology of the time, this too was impractical on Earth.

In the 1970s, Jerome Pearson independently conceived the idea of a space elevator, sometimes referred to as a synchronous tether, [5] and, in particular, analyzed a lunar elevator that can go through the L1 and L2 points, and this was found to be possible with materials then existing.

In 1977, Hans Moravec [6] and later Robert L. Forward investigated the physics of non-synchronous skyhooks, also known as rotating skyhooks, and performed detailed simulations of tapered rotating tethers that could pick objects off, and place objects onto, the Moon, Mars and other planets, with little loss, or even a net gain of energy. [7] [8]

In 1979, NASA examined the feasibility of the idea and gave direction to the study of tethered systems, especially tethered satellites. [1] [9]

In 1990, Eagle Sarmont proposed a non-rotating Orbiting Skyhook for an Earth-to-orbit / orbit-to-escape-velocity Space Transportation System in a paper titled "An Orbiting Skyhook: Affordable Access to Space". [10] [11] [12] In this concept a suborbital launch vehicle would fly to the bottom end of a Skyhook, while spacecraft bound for higher orbit, or returning from higher orbit, would use the upper end.

In 2000, NASA and Boeing considered a HASTOL concept, where a rotating tether would take payloads from a hypersonic aircraft (at half of orbital velocity) to orbit. [13]

Missions

Graphic of the US Naval Research Laboratory's TiPS tether satellite. Only a small part of the 4 km tether is shown deployed. TiPS lg.jpg
Graphic of the US Naval Research Laboratory's TiPS tether satellite. Only a small part of the 4 km tether is shown deployed.

A tether satellite is a satellite connected to another by a space tether. A number of satellites have been launched to test tether technologies, with varying degrees of success.

Types

There are many different (and overlapping) types of tether.

Momentum exchange tethers, rotating

Momentum exchange tethers are one of many applications for space tethers. Momentum exchange tethers come in two types; rotating and non-rotating. A rotating tether will create a controlled force on the end-masses of the system due to centrifugal acceleration. 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.

Skyhook

A rotating and a tidally stabilized skyhook in orbit Skyhooks.gif
A rotating and a tidally stabilized skyhook in orbit

A skyhook is a theoretical class of orbiting tether propulsion intended to lift payloads to high altitudes and speeds. [14] [15] [1] [16] [17] Proposals for skyhooks include designs that employ tethers spinning at hypersonic speed for catching high speed payloads or high altitude aircraft and placing them in orbit. [18]

Electrodynamics

Medium close-up view, captured with a 70 mm camera, shows Tethered Satellite System deployment. STS-75 Tethered Satellite System deployment.jpg
Medium close-up view, captured with a 70 mm camera, shows Tethered Satellite System deployment.

Electrodynamic tethers are long conducting wires, such as one deployed from a tether satellite, which can operate on electromagnetic principles as generators, by converting their kinetic energy to electrical energy, or as motors, converting electrical energy to kinetic energy. [1] Electric potential is generated across a conductive tether by its motion through the Earth's magnetic field. The choice of the metal conductor to be used in an electrodynamic tether is determined by a variety of factors. Primary factors usually include high electrical conductivity and low density. Secondary factors, depending on the application, include cost, strength, and melting point.

An electrodynamic tether was profiled in the documentary film Orphans of Apollo as technology that was to be used to keep the Russian space station Mir in orbit. [19] [20]

Formation flying

This is the use of a (typically) non-conductive tether to connect multiple spacecraft. Tethered Experiment for Mars inter-Planetary Operations (TEMPO³) is a proposed 2011[ clarification needed ] experiment to study the technique.

Universal Orbital Support System

Example of a possible layout using the Universal Orbital Support System Universal Orbital Support System.png
Example of a possible layout using the Universal Orbital Support System

A theoretical type of non-rotating tethered satellite system, it is a concept for providing space-based support to things suspended above an astronomical object. [21] The orbital system is a coupled mass system wherein the upper supporting mass (A) is placed in an orbit around a given celestial body such that it can support a suspended mass (B) at a specific height above the surface of the celestial body, but lower than (A).

Technical difficulties

Gravitational gradient stabilization

Description of the forces contributing towards maintaining a gravity gradient alignment in a tether system Fig11 Gravitational Gradient.PNG
Description of the forces contributing towards maintaining a gravity gradient alignment in a tether system

Instead of rotating end for end, tethers can also be kept straight by the slight difference in the strength of gravity over their length.

A non-rotating tether system has a stable orientation that is aligned along the local vertical (of the earth or other body). This can be understood by inspection of the figure on the right where two spacecraft at two different altitudes have been connected by a tether. Normally, each spacecraft would have a balance of gravitational (e.g. Fg1) and centrifugal (e.g. Fc1) forces, but when tied together by a tether, these values begin to change with respect to one another. This phenomenon occurs because, without the tether, the higher-altitude mass would travel slower than the lower mass. The system must move at a single speed, so the tether must therefore slow down the lower mass and speed up the upper one. The centrifugal force of the tethered upper body is increased, while that of the lower-altitude body is reduced. This results in the centrifugal force of the upper body and the gravitational force of the lower body being dominant. This difference in forces naturally aligns the system along the local vertical, as seen in the figure. [1]

Atomic oxygen

Objects in low Earth orbit are subjected to noticeable erosion from atomic oxygen due to the high orbital speed with which the molecules strike as well as their high reactivity. This could quickly erode a tether. [22]

Micrometeorites and space junk

Simple single-strand tethers are susceptible to micrometeoroids and space junk. Several systems have since been proposed and tested to improve debris resistance:

Large pieces of junk would still cut most tethers, including the improved versions listed here, but these are currently tracked on radar and have predictable orbits. Although thrusters could be used to change the orbit of the system, a tether could also be temporally wiggled in the right place, using less energy, to dodge known pieces of junk.[ citation needed ]

Radiation

Radiation, including UV radiation tend to degrade tether materials, and reduce lifespan. Tethers that repeatedly traverse the Van Allen belts can have markedly lower life than those that stay in low earth orbit or are kept outside Earth's magnetosphere.

Construction

Properties of useful materials

TSS-1R tether composition [NASA] TSS-1R tether composition.png
TSS-1R tether composition [NASA]

Tether properties and materials are dependent on the application. However, there are some common properties. To achieve maximum performance and low cost, tethers would need to be made of materials with the combination of high strength or electrical conductivity and low density. All space tethers are susceptible to space debris or micrometeoroids. Therefore, system designers will need to decide whether or not a protective coating is needed, including relative to UV and atomic oxygen.

For applications that exert high tensile forces on the tether, the materials need to be strong and light. Some current tether designs use crystalline plastics such as ultra-high-molecular-weight polyethylene, aramid or carbon fiber. A possible future material would be carbon nanotubes, which have an estimated tensile strength between 140 and 177  GPa (20.3 and 25.7 million psi; 1.38 and 1.75 million atm), and a proven tensile strength in the range 50–60 GPa (7.3–8.7 million psi; 490,000–590,000 atm) for some individual nanotubes. (A number of other materials obtain 10 to 20 GPa (1.5 to 2.9 million psi; 99,000 to 197,000 atm) in some samples on the nano scale, but translating such strengths to the macro scale has been challenging so far, with, as of 2011, CNT-based ropes being an order of magnitude less strong, not yet stronger than more conventional carbon fiber on that scale). [26] [27] [28]

For some applications, the tensile force on the tether is projected to be less than 65 newtons (15 lbf). [29] Material selection in this case depends on the purpose of the mission and design constraints. Electrodynamic tethers, such as the one used on TSS-1R,[ clarification needed ] may use thin copper wires for high conductivity (see EDT).

There are design equations for certain applications that may be used to aid designers in identifying typical quantities that drive material selection.

Space elevator equations typically use a "characteristic length", Lc, which is also known as its "self-support length" and is the length of untapered cable it can support in a constant 1 g gravity field.

,

where σ is the stress limit (in pressure units) and ρ is the density of the material.

Hypersonic skyhook equations use the material's "specific velocity" which is equal to the maximum tangential velocity a spinning hoop can attain without breaking:

For rotating tethers (rotovators) the value used is the material's 'characteristic velocity' which is the maximum tip velocity a rotating untapered cable can attain without breaking,

The characteristic velocity equals the specific velocity multiplied by the square root of two.

These values are used in equations similar to the rocket equation and are analogous to specific impulse or exhaust velocity. The higher these values are, the more efficient and lighter the tether can be in relation to the payloads that they can carry. Eventually however, the mass of the tether propulsion system will be limited at the low end by other factors such as momentum storage.

Practical materials

Proposed materials include Kevlar, ultra-high-molecular-weight polyethylene,[ citation needed ] carbon nanotubes and M5 fiber. M5 is a synthetic fiber that is lighter than Kevlar or Spectra. [30] According to Pearson, Levin, Oldson, and Wykes in their article "The Lunar Space Elevator", an M5 ribbon 30 mm (1.2 in) wide and 0.023 mm (0.91 mils) thick, would be able to support 2,000 kg (4,400 lb) on the lunar surface. It would also be able to hold 100 cargo vehicles, each with a mass of 580 kg (1,280 lb), evenly spaced along the length of the elevator. [5] Other materials that could be used are T1000G carbon fiber, Spectra 2000, or Zylon. [31]

Potential tether / elevator materials [5]
MaterialDensity
ρ
(kg/m3)
Stress limit
σ
(GPa)
Characteristic length
Lc = σ/ρg
(km)
Specific velocity
Vs = σ/ρ
(km/s)
Char. velocity
Vc = 2σ/ρ
(km/s)
Single-wall carbon nanotubes (individual molecules measured)2,266502,2004.76.6
Aramid, polybenzoxazole (PBO) fiber ("Zylon") [31] 1,3405.94502.13.0
Toray carbon fiber (T1000G)1,8106.43601.92.7
M5 fiber (planned values)1,7009.55702.43.3
M5 fiber (existing)1,7005.73401.82.6
Honeywell extended chain polyethylene fiber (Spectra 2000)9703.03161.82.5
DuPont Aramid fiber (Kevlar 49)1,4403.62551.62.2
Silicon carbide [ citation needed ]3,0005.91991.42.0

Shape

Tapering

For gravity stabilized tethers, to exceed the self-support length the tether material can be tapered so that the cross-sectional area varies with the total load at each point along the length of the cable. In practice this means that the central tether structure needs to be thicker than the tips. Correct tapering ensures that the tensile stress at every point in the cable is exactly the same. For very demanding applications, such as an Earth space elevator, the tapering can reduce the excessive ratios of cable weight to payload weight. In lieu of tapering a modular staged tether system maybe used to achieve the same goal. Multiple tethers would be used between stages. The number of tethers would determine the strength of any given cross-section. [32]

Thickness

For rotating tethers not significantly affected by gravity, the thickness also varies, and it can be shown that the area, A, is given as a function of r (the distance from the centre) as follows: [33]

where R is the radius of tether, v is the velocity with respect to the centre, M is the tip mass, is the material density, and T is the design tensile strength.

Mass ratio

Graph of tether mass to payload ratio versus the tip speed in multiples of the characteristic speed of the material Spinning tethers.png
Graph of tether mass to payload ratio versus the tip speed in multiples of the characteristic speed of the material

Integrating the area to give the volume and multiplying by the density and dividing by the payload mass gives a payload mass / tether mass ratio of: [33]

where erf is the normal probability error function.

Let ,

then: [34]

This equation can be compared with the rocket equation, which is proportional to a simple exponent on a velocity, rather than a velocity squared. This difference effectively limits the delta-v that can be obtained from a single tether.

Redundancy

In addition the cable shape must be constructed to withstand micrometeorites and space junk. This can be achieved with the use of redundant cables, such as the Hoytether; redundancy can ensure that it is very unlikely that multiple redundant cables would be damaged near the same point on the cable, and hence a very large amount of total damage can occur over different parts of the cable before failure occurs.

Material strength

Beanstalks and rotovators are currently limited by the strengths of available materials. Although ultra-high strength plastic fibers (Kevlar and Spectra) permit rotovators to pluck masses from the surface of the Moon and Mars, a rotovator from these materials cannot lift from the surface of the Earth. In theory, high flying, supersonic (or hypersonic) aircraft could deliver a payload to a rotovator that dipped into Earth's upper atmosphere briefly at predictable locations throughout the tropic (and temperate) zone of Earth. As of May 2013, all mechanical tethers (orbital and elevators) are on hold until stronger materials are available. [35]

Cargo capture

Cargo capture for rotovators is nontrivial, and failure to capture can cause problems. Several systems have been proposed, such as shooting nets at the cargo, but all add weight, complexity, and another failure mode. At least one lab scale demonstration of a working grapple system has been achieved, however. [36]

Life expectancy

Currently, the strongest materials in tension are plastics that require a coating for protection from UV radiation and (depending on the orbit) erosion by atomic oxygen. Disposal of waste heat is difficult in a vacuum, so overheating may cause tether failures or damage.

Control and modelling

Pendular motion instability

Electrodynamic tethers deployed along the local vertical ('hanging tethers') may suffer from dynamical instability. Pendular motion causes the tether vibration amplitude to build up under the action of electromagnetic interaction. As the mission time increases, this behavior can compromise the performance of the system. Over a few weeks, electrodynamic tethers in Earth orbit might build up vibrations in many modes, as their orbit interacts with irregularities in magnetic and gravitational fields.

One plan to control the vibrations is to actively vary the tether current to counteract the growth of the vibrations. Electrodynamic tethers can be stabilized by reducing their current when it would feed the oscillations, and increasing it when it opposes oscillations. Simulations have demonstrated that this can control tether vibration.[ citation needed ] This approach requires sensors to measure tether vibrations, which can either be an inertial navigation system on one end of the tether, or satellite navigation systems mounted on the tether, transmitting their positions to a receiver on the end.

Another proposed method is to use spinning electrodynamic tethers instead of hanging tethers. The gyroscopic effect provides passive stabilisation, avoiding the instability.

Surges

As mentioned earlier, conductive tethers have failed from unexpected current surges. Unexpected electrostatic discharges have cut tethers (e.g. see Tethered Satellite System Reflight (TSS‑1R) on STS‑75), damaged electronics, and welded tether handling machinery. It may be that the Earth's magnetic field is not as homogeneous as some engineers have believed.

Vibrations

Computer models frequently show tethers can snap due to vibration.

Mechanical tether-handling equipment is often surprisingly heavy, with complex controls to damp vibrations. The one ton climber proposed by Brad Edwards for his Space Elevator may detect and suppress most vibrations by changing speed and direction. The climber can also repair or augment a tether by spinning more strands.

The vibration modes that may be a problem include skipping rope, transverse, longitudinal, and pendulum. [37]

Tethers are nearly always tapered, and this can greatly amplify the movement at the thinnest tip in whip-like ways.

Other issues

A tether is not a spherical object, and has significant extent. This means that as an extended object, it is not directly modelable as a point source, and this means that the center of mass and center of gravity are not usually colocated. Thus the inverse square law does not apply except at large distances, to the overall behaviour of a tether. Hence the orbits are not completely Keplerian, and in some cases they are actually chaotic. [38]

With bolus designs, rotation of the cable interacting with the non-linear gravity fields found in elliptical orbits can cause exchange of orbital angular momentum and rotation angular momentum. This can make prediction and modelling extremely complex.

See also

Related Research Articles

<span class="mw-page-title-main">Interplanetary spaceflight</span> Crewed or uncrewed travel between stars or planets

Interplanetary spaceflight or interplanetary travel is the crewed or uncrewed travel between stars and planets, usually within a single planetary system. In practice, spaceflights of this type are confined to travel between the planets of the Solar System. Uncrewed space probes have flown to all the observed planets in the Solar System as well as to dwarf planets Pluto and Ceres, and several asteroids. Orbiters and landers return more information than fly-by missions. Crewed flights have landed on the Moon and have been planned, from time to time, for Mars, Venus and Mercury. While many scientists appreciate the knowledge value that uncrewed flights provide, the value of crewed missions is more controversial. Science fiction writers propose a number of benefits, including the mining of asteroids, access to solar power, and room for colonization in the event of an Earth catastrophe.

<span class="mw-page-title-main">Spacecraft propulsion</span> Method used to accelerate spacecraft

Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric entry.

<span class="mw-page-title-main">Space elevator</span> Proposed type of space transportation system

A space elevator, also referred to as a space bridge, star ladder, and orbital lift, is a proposed type of planet-to-space transportation system, often depicted in science fiction. The main component would be a cable anchored to the surface and extending into space. An Earth-based space elevator would consist of a cable with one end attached to the surface near the equator and the other end attached to a counterweight in space beyond geostationary orbit. The competing forces of gravity, which is stronger at the lower end, and the upward centrifugal force, which is stronger at the upper end, would result in the cable being held up, under tension, and stationary over a single position on Earth. With the tether deployed, climbers (crawlers) could repeatedly climb up and down the tether by mechanical means, releasing their cargo to and from orbit. The design would permit vehicles to travel directly between a planetary surface, such as the Earth's, and orbit, without the use of large rockets.

<span class="mw-page-title-main">Solar sail</span> Space propulsion method using Sun radiation

Solar sails are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large surfaces. A number of spaceflight missions to test solar propulsion and navigation have been proposed since the 1980s. The first spacecraft to make use of the technology was IKAROS, launched in 2010.

<span class="mw-page-title-main">STS-75</span> 1996 American crewed spaceflight

STS-75 was a 1996 NASA Space Shuttle mission, the 19th mission of the Columbia orbiter.

<span class="mw-page-title-main">Skyhook (structure)</span> Proposed momentum exchange tether

A skyhook is a proposed momentum exchange tether that aims to reduce the cost of placing payloads into low Earth orbit. A heavy orbiting station is connected to a cable which extends down towards the upper atmosphere. Payloads, which are much lighter than the station, are hooked to the end of the cable as it passes, and are then flung into orbit by rotation of the cable around the center of mass. The station can then be reboosted to its original altitude by electromagnetic propulsion, rocket propulsion, or by deorbiting another object with the same kinetic energy as transferred to the payload.

<span class="mw-page-title-main">Orbital decay</span> Process that leads to gradual decrease of the distance between two orbiting bodies

Orbital decay is a gradual decrease of the distance between two orbiting bodies at their closest approach over many orbital periods. These orbiting bodies can be a planet and its satellite, a star and any object orbiting it, or components of any binary system. If left unchecked, the decay eventually results in termination of the orbit when the smaller object strikes the surface of the primary; or for objects where the primary has an atmosphere, the smaller object burns, explodes, or otherwise breaks up in the larger object's atmosphere; or for objects where the primary is a star, ends with incineration by the star's radiation. Collisions of stellar-mass objects are usually accompanied by effects such as gamma-ray bursts and detectable gravitational waves.

<span class="mw-page-title-main">Lunar space elevator</span> Proposed transportation system

A lunar space elevator or lunar spacelift is a proposed transportation system for moving a mechanical climbing vehicle up and down a ribbon-shaped tethered cable that is set between the surface of the Moon "at the bottom" and a docking port suspended tens of thousands of kilometers above in space at the top.

Rotovator can mean:

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.

<span class="mw-page-title-main">Launch loop</span> Proposed system for launching objects into orbit

A launch loop, or Lofstrom loop, is a proposed system for launching objects into orbit using a moving cable-like system situated inside a sheath attached to the Earth at two ends and suspended above the atmosphere in the middle. The design concept was published by Keith Lofstrom and describes an active structure maglev cable transport system that would be around 2,000 km (1,240 mi) long and maintained at an altitude of up to 80 km (50 mi). A launch loop would be held up at this altitude by the momentum of a belt that circulates around the structure. This circulation, in effect, transfers the weight of the structure onto a pair of magnetic bearings, one at each end, which support it.

<span class="mw-page-title-main">Orbital ring</span> Conceptual artificial ring around the Earth

An orbital ring is a concept of an artificial ring placed around a body and set rotating at such a rate that the apparent centrifugal force is large enough to counteract the force of gravity. For the Earth, the required speed is on the order of 10 km/sec, compared to a typical low Earth orbit velocity of 8 km/sec. The structure is intended to be used as a space station or as a planetary vehicle for very high-speed transportation or space launch.

This is an alphabetical list of articles pertaining specifically to aerospace engineering. For a broad overview of engineering, see List of engineering topics. For biographies, see List of engineers.

<span class="mw-page-title-main">Electrodynamic tether</span> Long conducting wires which can act as electrical motors or generators

Electrodynamic tethers (EDTs) are long conducting wires, such as one deployed from a tether satellite, which can operate on electromagnetic principles as generators, by converting their kinetic energy to electrical energy, or as motors, converting electrical energy to kinetic energy. Electric potential is generated across a conductive tether by its motion through a planet's magnetic field.

Jerome Pearson was an American engineer and space scientist best known for his work on space elevators, including a lunar space elevator. He was president of STAR, Inc., and has developed aircraft and spacecraft technology for the United States Air Force, DARPA, and NASA. He held several patents and was the author of nearly 100 publications in aircraft, spacecraft, electrodynamic tethers, SETI, and global climate control.

<span class="mw-page-title-main">Non-rocket spacelaunch</span> Concepts for launch into space

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.

Field propulsion is the concept of spacecraft propulsion where no propellant is necessary but instead momentum of the spacecraft is changed by an interaction of the spacecraft with external force fields, such as gravitational and magnetic fields from stars and planets. Proposed drives that use field propulsion are often called a reactionless or propellantless drive.

<span class="mw-page-title-main">Space tether missions</span> Space technology using tethers

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.

Hypothetical technology is technology that does not exist yet, but that could exist in the future. This article presents examples of technologies that have been hypothesized or proposed, but that have not been developed yet. An example of hypothetical technology is teleportation.

This glossary of aerospace engineering terms pertains specifically to aerospace engineering, its sub-disciplines, and related fields including aviation and aeronautics. For a broad overview of engineering, see glossary of engineering.

References

  1. 1 2 3 4 5 Cosmo, M. L.; Lorenzini, E. C., eds. (December 1998). "Tethers In Space Handbook" (PDF) (3rd ed.). NASA. Archived (PDF) from the original on 29 April 2010. Retrieved 20 October 2010. See also version of NASA MSFC Archived 2011-10-27 at the Wayback Machine ; available on Scribd Archived 2016-04-21 at the Wayback Machine .
  2. Finckenor, Miria; AIAA Technical Committee (December 2005). "Space Tether". Aerospace America: 78.
  3. Bilen, Sven; AIAA Technical Committee (December 2007). "Space Tethers". Aerospace America: 89.
  4. Artsutanov, Yuri (July 31, 1960). "V Kosmos na Electrovoze" (PDF). Komsomolskaya Pravda (in Russian).
  5. 1 2 3 Pearson, Jerome; Eugene Levin; John Oldson & Harry Wykes (2005). "Lunar Space Elevators for Cislunar Space Development: Phase I Final Technical Report" (PDF). Archived (PDF) from the original on 2016-03-03.
  6. "The Journal of the Astronautical Sciences, v25#4, pp. 307–322, Oct–Dec 1977". cmu.edu. Archived from the original on 3 October 2017. Retrieved 3 May 2018.
  7. Moravec, Hans (1986). "Orbital Bridges" . Retrieved January 8, 2023.
  8. Hans Moravec, "Non-Synchronous Orbital Skyhooks for the Moon and Mars with Conventional Materials" Archived 1999-10-12 at archive.today (Hans Moravec's thoughts on skyhooks, tethers, rotovators, etc., as of 1987) (accessed 10 October 2010)
  9. Joseph A. Carroll and John C. Oldson, “Tethers for Small Satellite Applications” Archived 2011-07-16 at the Wayback Machine , presented at the 1995 AIAA / USU Small Satellite Conference in Logan, Utah, United States (accessed 20 October 2010)
  10. Sarmont, Eagle (May 26, 1990). An Orbiting Skyhook: Affordable Access to Space (Archived copy). Anaheim, CA: International Space Development Conference. Archived from the original on 2014-02-22. Retrieved 2014-02-09.
  11. Sarmont, Eagle (October 1994). "How an Earth Orbiting Tether Makes Possible an Affordable Earth-Moon Space Transportation System". SAE Technical Paper Series (Report). SAE Technical Paper 942120. Vol. 1. doi:10.4271/942120. Archived from the original on 2014-02-22. Retrieved 2014-02-09.
  12. Smitherman, D.V., "Space Elevators, An Advanced Earth-Space Infrastructure for the New Millennium", NASA/CP-2000-210429
  13. Thomas J. Bogar; et al. (7 January 2000). "Hypersonic Airplane Space Tether Orbital Launch System: Phase I Final Report" (PDF). NASA Institute for Advanced Concepts. Research Grant No. 07600-018. Archived from the original (PDF) on 24 July 2011.
  14. H. Moravec, "A non-synchronous orbital skyhook". Journal of the Astronautical Sciences, vol. 25, no. 4, pp. 307–322, 1977.
  15. G. Colombo, E. M. Gaposchkin, M. D. Grossi, and G. C. Weiffenbach, “The sky-hook: a shuttle-borne tool for low-orbital-altitude research,” Meccanica, vol. 10, no. 1, pp. 3–20, 1975.
  16. L. Johnson, B. Gilchrist, R. D. Estes, and E. Lorenzini, "Overview of future NASA tether applications," Advances in Space Research, vol. 24, no. 8, pp. 1055–1063, 1999.
  17. E. M. Levin, "Dynamic Analysis of Space Tether Missions", American Astronautical Society, Washington, DC, USA, 2007.
  18. Hypersonic Airplane Space Tether Orbital Launch (HASTOL) System: Interim Study Results Archived 2016-04-27 at the Wayback Machine
  19. "Orphans of Apollo". World Press. Archived from the original on 21 June 2012. Retrieved 30 January 2013.
  20. Foust, Jeff (July 23, 2001). "Preview: Orphans of Apollo". The Space Review. Archived from the original on 5 February 2013. Retrieved 30 January 2013.
  21. Wood, Charlie (29 March 2017). "A 20-mile long 'spacescraper' dangling from an asteroid: Could it work?". Christian Science Monitor. Archived from the original on 31 March 2017.
  22. Michel van Pelt (2009). Space Tethers and Space Elevators. Springer Science & Business Media. p. 163. ISBN   978-0-387-76556-3.
  23. "TiPS: Missuion Objectives". Archived from the original on July 8, 2007. Retrieved 2011-10-06.
  24. NOSS Launch Data Archived 2011-09-28 at the Wayback Machine (see NOSS 2-3, which deployed TiPS)
  25. Ohkawa, Y.; Kawamoto, S.; Nishida, S. I.; Kitamura, S. (2009). "Research and Development of Electrodynamic Tethers for Space Debris Mitigation". Transactions of the Japan Society for Aeronautical and Space Sciences, Space Technology Japan. 7: Tr_T2_5 – Tr_2_10. Bibcode:2009TrSpT...7Tr2.5O. doi: 10.2322/tstj.7.Tr_2_5 .
  26. "Nanotube Fibers". science-wired.blogspot.com. Archived from the original on 1 February 2016. Retrieved 3 May 2018.
  27. Tensile tests of ropes of very long aligned multiwall carbon nanotubes Archived 2011-07-22 at the Wayback Machine
  28. Tensile Loading of Ropes of Single-Wall Carbon Nanotubes and their Mechanical Properties
  29. NASA, TSS-1R Mission Failure Investigation Board, Final Report, May 31, 1996 (accessed 7 April 2011)
  30. Bacon 2005.
  31. 1 2 Specifications for commercially available PBO (Zylon) cable: "PBO (Zylon) The high performance fibre" Archived 2010-11-15 at the Wayback Machine (accessed Oct. 20, 2010)
  32. WO2017031482A1 (U.S. Patent #)
  33. 1 2 "Tether Transport from LEO to the Lunar Surface", R. L. Forward, AIAA Paper 91-2322, 27th Joint Propulsion Conference, 1991 Archived 2011-05-17 at the Wayback Machine
  34. Non-Synchronous Orbital Skyhooks for the Moon and Mars with Conventional Materials - Hans Moravec
  35. Jillian Scharr, "Space Elevators On Hold At Least Until Stronger Materials Are Available, Experts Say", Huffington Post, May 29, 2013 "Space Elevators on Hold at Least Until Stronger Materials Are Available, Experts Say". HuffPost . 29 May 2013. Archived from the original on 2014-03-02. Retrieved 2014-04-06.
  36. "NASA - NASA Engineers, Tennessee College Students Successfully Demonstrate Catch Mechanism for Future Space Tether". Archived from the original on 2010-11-26. Retrieved 2011-03-26. NASA Engineers, Tennessee College Students Successfully Demonstrate Catch Mechanism for Future Space Tether
  37. Tether dynamics Archived 2007-07-17 at the Wayback Machine
  38. Mortari, Daniele (January 2008). "Ultra Long Orbital Tethers Behave Highly Non-Keplerian and Unstable | Daniele Mortari - Academia.edu". Archived from the original on 2017-10-04. Retrieved 2017-11-01. Ultra Long Orbital WSEAS TRANSACTIONS on MATHEMATICS: Tethers Behave Highly Non-Keplerian and Unstable- Daniele Mortari

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