Space tether missions | Wikipedia audio article

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 stabilization and orbital plasma dynamics the missions have met with varying degrees of success a few have been highly successful topic description tethered satellites are composed of three parts the base satellite tether and sub satellite the base satellite contains the sub satellite and tether until deployment sometimes the base satellite is another basic satellite other times it could be a spacecraft space station or the moon the tether is what keeps the two satellites connected the sub satellite is released from the base assisted by a spring ejection system centrifugal force or gravity gradient effects tethers can be deployed for a range of applications including electro dynamic propulsion momentum exchange artificial gravity deployment of sensors or antennas etc tether deployment may be followed by a station-keeping phase in particular if the target state is a vertical system orientation and sometimes if the deployment system allows a retraction the station-keeping phase and retraction phase need active control for stability especially when atmospheric effects are taken into account when there are no simplifying assumptions the dynamics become overly difficult because they are then governed by a set of ordinary and partial nonlinear non autonomous and coupled differential equations these conditions create a list of dynamical issues to consider three dimensional rigid body dynamics librational motion of the station and sub satellite swinging in plane and out of plane motions of the tether of finite mass offset of the tether attachment point from the base satellite center of mass as well as controlled variations of the offset transverse vibrations of the tether external forces topic tether flights on human space missions topic Gemini 11 in 1966 Gemini 11 deployed a 30 meters 100 foot tether which was stabilized by a rotation which gave 0.0001 5 grams topic shuttle TSS missions topic TSS one mission tethered satellite system one TSS one was proposed by NASA in the Italian space agency ASI in the early 1970s by Mario grossie of the Smithsonian Astrophysical Observatory and Jews F a Colombo of Padua University it was a joint NASA Italian space agency project was flown in 1992 during STS 46 aboard the space shuttle Atlantis from the 31st of July to the 8th of August the purposes of the TSS 1 mission were to verify the tether concept of gravity gradient stabilization and to provide a research facility for investigating space physics and plasma electrodynamics this mission uncovered several aspects about the dynamics of the tethered system although the satellite did not fully deploy it stuck at 78 meters after that snag was resolved its deployment continued to a length at 256 metres before sticking again where the effort finally ended the total proposed length was 20,000 meters a protruding bulb due to a late-stage modification of the deployment real system jam the deployment mechanism and prevented deployment to full extension despite this issue the results showed that the basic concept of long gravity gradient stabilized tethers were sound it also settled several short deployment dynamics issues reduced safety concerns and clearly demonstrated the feasibility of deploying the satellite to long distances the voltage and current reached using the short tether lengths were too low for most of the experiments to be run however low voltage measurements were made along with recording the variations of tether induced forces and currents new information was gathered on the return tether current the mission was reef loan in 1990 six is tss one our topic tss one our mission four years later as a follow-up mission to TSS 1 the TSS 1 our satellite was released in latter February 1996 from the space shuttle Columbia on the STS 75 mission the TSS 1 our mission objective was to deploy the tether 20.7 km/h mind they're collecting data the TSS 1 our mission was to conduct exploratory experiments in space plasma physics projections indicated that the motion of the long conducting tether through the Earth's magnetic field would produce an EMF that would drive a current through the tether system TSS 1 our was deployed to 19.7 km/h 111 place in the insulation despite the termination of the tether deployment before full extension the extension achieved was long enough to verify numerous scientific speculations these findings included the measurements of the motional EMF the satellite potential the orbiter potential the current in the tether the changing resistance in the tether the charged particle distributions around a highly charged spherical satellite and the ambient electric field in addition a significant finding concerns the current collection at different potentials on a spherical end mass measured currents on the tether far exceeded predictions of previous numerical models by up to a factor of three a more descriptive explanation of these results can be found in Thompson at all improvements have been made in modeling the electron charging of the shuttle and how it affects current collection and in the interaction of bodies with surrounding plasma as well as the production of electrical power a second mission TSS two had been proposed to use the tether concept for upper atmospheric experimentation but was never flown topic tethers on satellite missions longer tether systems have also been used on satellite missions both operationally as yo-yoed Espen systems and in missions designed to test tether concepts and dynamics topic yo-yoed Espen short tether systems are commonly used on satellites and robotic space probes most notably tethers are used in the yoyo to spin mechanism often used in systems where a probe set spinning during a solid rocket injection motor firing but needs the spin removed during flight in this mechanism weights on the end of long cables are deployed away from the body of the spinning satellite when the cables are cut much or all of the angular momentum of the spin is transferred to the discarded weights as an example the dawn mission utilized two three kilograms of weights deployed on 12 meter cables topic NASA small expendable deployer system experiments in 1993 and 1994 NASA launched three missions using the small expendable deployer system SCDS which deployed 20 kilometers SED S&S see ds2 and 500 meter PMG tethers attached to a spent delta to second stage the three experiments were the first successful flights of long tethers in orbit and demonstrated both mechanical and electrodynamic tether operation topic SC DSi the first fully successful orbital flight test of a long tether system was SC ds1 which tested the simple deploy only small expendable deployer system the tether swung to the vertical and was cut after one orbit this slung the payload and tether from Guam onto a reentry trajectory off the coast of Mexico the re-entry was accurate enough that a pre-positioned observer was able to videotape the payload re-entry and burn up topic SCDS to SC ds2 was launched on a delta along with a gps block to satellite on the 9th of march 1994 a feedback braking limited the swing after deployment to four degrees the payload returned data for eight hours until its battery died during this time tether talk spun it up to four revolutions per minute the tether suffered a cut three point seven days after deployment the payload re-entered as expected within hours but the 7.2 kilometers length at the Delta end survived with no further cuts until reentry on the 7th of May 1994 the tether was an easy naked-eye object when lit by the Sun and viewed against a dark sky in these experiments tether models were verified and the tests demonstrated that re entry vehicle can be downwardly deployed into a reentry orbit using tethers topic PMG a follow-on experiment the plasma motor generator PMG used the SCDS deployer to deploy a 500m tether to demonstrate electrodynamic tether operation the PMG was planned to test the ability of a hollow cathode assembly HCA to provide a low impedance bipolar electric current between a spacecraft and the ionosphere in addition other expectations were to show that the mission configuration could function as an orbit boosting motor as well as a generator by converting orbital energy into electricity the tether was a 500 meters length of insulated 18 gauge copper wire the mission was launched on the 26th of June 1993 as the secondary payload on a delta 2 rocket the total experiment lasted approximately 7 hours in that time the results demonstrated that current is fully reversible and therefore was capable of generating power in orbit boosting modes the hollow cathode was able to provide a low-power way of connecting the current to and from the ambient plasma this means that the HC demonstrated its electron collection and emission capabilities topic NRL tips and 8x experiments topic tips the tether physics and survivability experiment tips was launched in 1996 as a project of the US Naval Research Laboratory it incorporated a four thousand meter tether the two tethered objects were called Ralph and Norton tips was visible from the ground with binoculars or a telescope and was occasionally accidentally spotted by amateur astronomers the tether broke in July 2006 this long-term statistical data point is in line with debris models published by Jay Carroll after the SE ds2 mission and ground tests by d-sub are from two Munchen predictions of a maximum of two years survivability for tips based on some other ground tests have shown to be overly pessimistic eg McBride Taylor Penson the early cut of the SCDS to their width must be considered an anomaly possibly related to the impact of upper stage debris topic 8x the advanced tether experiment 8x was a follow-on to the tips experiment designed and built by the naval center for space technology 8x flew as part of the ste x space technology experiment mission 8x had to end masses connected by a polyethylene tether that was intended to deploy to a length of six kilometers in length and was intended to test a new tether deployment scheme new tether material ActiveX control and survivability 8x was deployed on the 16th of January 1999 and ended 18 minutes later after deploying only 22 metres of tether the jettison was triggered by an automatic protection system designed to save ste X if the tether began to stray from it's expected departure angle which was ultimately caused by excessive slacked ever as a result of the deployment failure none of the desired 8x goals were achieved topic young engineers satellite yes topic yes in 1997 the European Space Agency launched the young engineers satellite yes of about 200 kilograms into GTO with a 35 kilometers double strand tether and plan to deorbit a probe at near interplanetary speed by swinging deployment of the tether system the orbit achieved was not as initially planned for the tether experiment and for safety considerations the tether was not deployed topic yes.2 10 years after yes its successor the young engineers satellite to yes.2 was flown the yes.2 was a 36 kilogram student-built tether satellite part of esa s Foton m3 microgravity mission the yes.2 satellite employed a 32 kilometers tether to deorbit a small reentry capsule 30 know the yes.2 satellite was launched on the 14th of september 2007 from Baikonur the communication system on the capsule failed and the capsule was lost but deployment telemetry indicated that the tether deployed to full length and that the capsule presumably deorbited as planned it has been calculated that 14o was inserted into a trajectory towards a landing site in Kazakhstan but no signal was received the capsule was not recovered topic kite experiment the kounotori integrated tether experiment kite was a test of tether technology on the Japanese h2 Transfer Vehicle HTV six space station resupply vehicle launched by the Japan aerospace exploration agency J AXA in December 2016 after undocking from the International Space Station on January 27 2016 it was intended to deploy a 700 meter 2,300 feet electrodynamic tether however a failure resulted in the tether not deploying the vehicle burned up in the atmosphere without deployment topic cubesat tether missions cube SATs are small low-cost satellites that are typically launched as secondary payloads on other missions often built and operated as student projects several CubeSat missions have attempted to deploy tethers so far without success topic masked the multi application survivable tether mast launched three 1-kilogram CubeSat modules with a 1km tether two of the CubeSat modules ted and ralph were intended as end masses on the deployed tether while the third gadget served as a climber that could move up and down the tether the experiment used a multi line Hoyt ever designed to be damage resistant the objectives of the mast experiment were to obtain on-orbit data on the survivability of space tethers in the micrometeorite debris orbital environment to study the dynamics of tethered formations of spacecraft and rotating tether systems and to demonstrate momentum exchange tether concepts the experiment Hardware was designed under a NASA small business technology transfer STTR collaboration between tethers unlimited Inc and Stanford University with 2e developing the tether tether deploy a tether inspection subsystem satellite avionics and software and Stanford students developing the satellite structures and assisting with the avionics design as a part of the University CubeSat program in April 2007 the mast was launched as a secondary payload on a dnepr rocket into a 98 degrees 647 by 782 kilometres orbit the experiment team made contact with the gadget Pico satellite but not with Ted the tether deploy a Pico satellite while the system was designed so that the satellites would separate even if communications were not established to the tether deployer the system did not fully deploy radar measurements show that Heather deployed just one meter topic stars the space tethered autonomous robotics satellite stars or Kukai mission developed by the CAG our satellite development project at CAG our University Japan was launched the 23rd of January 2009 as a CubeSat secondary payload aboard hii a flight 15 which also launched geo SAT after launch the satellite was named k UK AI and consisted of two sub satellites ku and KY to be linked by a 5 metre tether it was successfully separated from the rocket and transferred into the planned orbit but the tether deployed only to a length of several centimeters due to the launch lock trouble of the tether real mechanism topic stars too a follow-on space tethered autonomous robotic satellite stars to ionged on the 27th of february 2014 as a secondary payload of board an h2 a rocket the nine kilogram student satellite flew a 300 meter 980 feet electrodynamic tether made from ultra thin wires of stainless steel and aluminium the mission completed after two months and deorbited on the 26th of April 2014 one objective of this program was to demonstrate possible technology for two orbiting space debris the experiment was only partially successful and tether deployment could not be confirmed the orbit decayed from 350 kilometers to 280 kilometers in 50 days considerably faster than the other cube SATs launched on the same mission an indirect indication that its tether deployed increasing the drag however telescopic photography of the satellite from the ground showed the satellite as a single point rather than two objects the experimenters suggest that this may have been due to the tether extending but being tangled by rebound topic est-ce ube 1 est-ce ube 1 was an Estonian mission to test an electric sail in orbit launched in 2013 it was designed to deploy a tether using centrifugal deployment however the tether failed to deploy topic sounding rocket flights topic charged to the co-operative high altitude rocket gun experiment charged to was jointly developed by Japan and NASA to observe the current collection along with other phenomena the major objective was to measure the payload charging and return currents during periods of electron emission secondary objectives were related to plasma processes associated with direct current and pulsed firings of a low power electron beam source on the 14th of December 1985 the charge mission was launched at White Sands Missile Range New Mexico the results indicated that it is possible to enhance the electron current collection capability of positively charged vehicles by means of deliberate neutral gas releases into an undisturbed space plasma in addition it was observed that the release of neutral gas or argon gas into the undisturbed plasma region surrounding a positively biased platform has been found to cause enhancements to electron current collection this was due to the fact that a fraction of the gas was ionized which increased the local plasma density and therefore the level of returned current topic Oedipus Oedipus observations of electric field distribution in the ionospheric plasma a unique strategy consisted of two sounding rocket experiments that used spinning conductive tethers as a double probe for measurements of weak electric fields in the Aurora they were launched using black brandt three-stage sounding rockets oedipus are launched on the 30th of January 1989 from Andrea in Norway the tethered payload consisted of two spinning sub payloads with a mass of 84 and 131 kilograms connected by a spinning tether the flight established a record for the length of an electrodynamic tether in space at that time 958 metres the tether was a Teflon coated stranded tin copper wire of 0.85 millimeters diameter and it was deployed from a spool type reel located on the forward sub payload oedipus sea was launched on the 6th of november 1995 from the poker flat research range north of Fairbanks Alaska on a black Brandt 12 sounding rocket the flight reached an Apogee of 843 kilometers and deployed a tether of the same type used in the EDA per-say to a length of 1174 meters it included a tether dynamics experiment to derive theory and develop simulation and animation software for analyses of multi body dynamics and control of the spinning tether configuration provide dynamics and control expertise for the suborbital tethered vehicle and for the science investigations develop an attitude stabilization scheme for the payloads and support EDA Percy payload development and acquire dynamics data during flight to compare with pre-flight simulation topic t-rex on the 31st of August 2010 an experiment by the Japan aerospace exploration agency jxa on space tether experiment called tether technologies rocket experiment t-rex sponsored by the Japanese aerospace exploration agency is a SJ AXA was launched on sounding rocket S 500 and 2025 from Yuchun Ora Space Centre Japan reaching a maximum altitude of 309 kilometers t-rex was developed by an international team led by the Kanagawa Institute of Technology Nihon University to test a new type of electro dynamic tether EDT the 300 M tape tether deployed as scheduled and a video of deployment was transmitted to the ground successful tether deployment was verified as was the fast ignition of a hollow cathode in the space environment the experiment demonstrated ur foldaway flat tether deployment system the educational experiment featured the first bare taped tether deployment ie without insulation the tether itself acts as a node and collects electrons 130 meters of the total of 300 meters of tether was deployed fire hose style purely driven by inertia and limited by friction following a powerful spring initiated ejection accurate differential GPS data of the deployment was recorded and video taken from the end masses topic proposed and future missions topic proceeds the use of a bear section of a spaceborne electrodynamic tether for an electron collection device has been suggested as a promising alternative to end body electron collectors for certain electrodynamic tether applications the bear tether concept was to be tested first during NASA's propulsive small expendable deployer system precedes mission while the mission was cancelled after nasa's space shuttle columbia accident the concept could potentially be undertaken in the future topic stars see a follow-on to the earliest stars and stars to satellites stars see space tethered autonomous robotic satellite Cube is to be launched from the International Space Station the satellite was designed by a team from Shizuka University the satellite weighs two point six six kilograms consisting of two 1u 10 centimeter cubes at modules connected with a 100 M Kevlar tether with a diameter of zero point four millimeters after being delivered to the International Space Station the satellite will be released from the Japanese experiment module Kibo topic CubeSat technology tether electrodynamic propulsion CubeSat experiment te PCE is a Naval Research Laboratory electrodynamic tether experiment based on a triple CubeSat configuration currently planned for launch is a secondary payload te PCE uses two nearly identical end masses with a stasis spring between them the spring will separate the end masses and start deployment of a one kilometer long braided tape conducting tether passive braking will be used to reduce speed and hence recoil at the end of deployment the satellite is intended to drive an electrodynamic current in either direction it is intended to be able to raise or lower the orbit by several kilometers per day change libration state change orbit plane and actively maneuver the satellite underwent a successful deployment test in May 2010 in support of te PCE the u.s.

Naval Academy is developing tether set a satellite system with a one kilometer tether to test the te PCE tether deployment hardware in Leo and to analyze the dynamics during and after deployment twin end masses are 1.5 u cube sets that will contain GPS and other sensors to accurately measure tether libration and orbital motion data although the tether is conductive it will not be used to generate electro dynamic forces topic mighty the miniature tether electrodynamics experiment mighty is a University of Michigan CubeSat tether experiment selected by NASA in 2015 as a university CubeSat space mission candidate it is to deploy a sub satellite of approximately 8 centimeters x 8 centimeters x 2 centimeters from a 3u cube set to test satellite electrodynamics tethers in the space environment the schedule shows flight hardware to be delivered in the second quarter of 2017.

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