propellant less propulsion

8/3/2019 Propellant Less Propulsion

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Tethered Propulsion Tether propulsion requires no fuel, is completely reusable and

environmentally clean, and provides all these features at lowcost.

Space tethers are cables, usually long and very strong, which canbe used for propulsion, stabilization, or maintaining theformation of space systems by determining the trajectory ofspacecraft and payloads. Depending on the mission objectivesand altitude, spaceflight using this form of spacecraft propulsionmay be significantly less expensive than spaceflight using rocketengines.

Three main techniques for employing space tethers are indevelopment


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Types

Electrodynamic tetherThis is a conductive tether that carries a current that can generatethrust or drag from a planetary magnetic field, in much the same wayas an electric motor.

Momentum exchange tetherThis is a rotating tether that would grab a spacecraft and then releaseit at later time. Doing this can transfer momentum and energy fromthe tether to and from the spacecraft with very little loss; this can beused for orbital maneuvering.

Tethered Formation FlyingThis is typically a non-conductive tether that accurately maintains aset distance between space vehicles.


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Consider a Normal Satellite missionLaunch rocket/space shuttleShuttle deploys payload (usually satellite)Satellite performs function, and then eventually loses enoughmomentum to fall out of orbitIf Satellite needs more time in space, fuel must be shipped up to the

satelliteBottom Line: needs fuel

Disadvantages of Fuel:Expensive

Refueling MIR space station costs estimated at about $1 billion.Limited Supply

Earth is already running out of fossil fuels, nuclear/renewableresources not yet a viable solution for propulsion in space

We need a propellant-less propulsion


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Earth has magnetic fieldEarth has electric fieldBasic law of Physics :

F = B x IIf we could utilize theEarths electric and magneticfields by driving current inthe right direction, then wecan generate anelectromotive forcesufficient for use in orbit

Implementation


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HowKeep it simple:

Generate current along a straight lineUse a taut conducting wire (Tether) to channel thecurrent

Tether needs to be kept taut and orientedproperly in the magnetic fieldAnother basic rule of physics: if twomasses connected by a tether are in orbit,the masses will align themselves along thelocal vertical regardless of the starting


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Electrodynamic TetheredElectrodynamic tethers (EDTs) are long conducting wires, suchas one deployed from a tether satellite, which can operate onelectromagnetic principles as generators, by converting their

kinetic energy to electrical energy, or as motors, convertingelectrical energy to kinetic energy. Electric potential isgenerated across a conductive tether by its motion through theEarth's magnetic field. The choice of the metal conductor to beused in an electrodynamic tether is determined by a variety of

factors.Primary factors usually include high electrical conductivity, andlow density.Secondary factors, depending on the application, include cost,

strength, and melting point.


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A space object, i.e. a satellite in Earth orbit, or any other

space object either natural or man made, is physicallyconnected to the tether system.The tether system comprises a deployer from which aconductive tether having a bare segment extends upward

from space object. The positively biased anode end oftether collects electrons from the ionosphere as spaceobject moves in direction across the Earth's magneticfield.These electrons flow through the conductive structure of

the tether to the power system interface, where itsupplies power to an associated load, not shown. Theelectrons then flow to the negatively biased cathode

where electrons are ejected into the space plasma, thus

completing the electric circuit.


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A composite schematic of the complex array of physical effects andcharacteristics observed in the near environment of the TSS satellite.


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Theory and Experiment H.H BritoTwo series of tests were conducted during the period of 1993-1997 byHector Hugo Brito, that under the assumption of Minkowskis Energy-Momentum, tensor being the right one (Abraham-Minkowsckoi ntroversy)the electromagnetic field can modify the inertial properties of the

generating device given suitable charge and current distributions. Thisexperiment consists of mounting the device as a seismic mass top amechanical suspension. By supplying a periodic voltage to the coils at aFrequency close to the fundamental frequency of the seismic suspensionthe expected mechanical effect from inertia variation would cause thefixture to resonate, adding up to the micro seismic noise induced

vibration. Practically in all cases, the results consistently point to amechanical vibration induced by matter-electromagnetic field momentumexchange as predicted by Minkowskis formulation after all other sources ofvibration were taken into account or removed when possible.


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H H. Brito concluded that:Propellantless propulsion, as a mechanism not

requiring reaction mass or beamed power, does notseem to be out of reach, unless from the theoreticalpoint of view. Space-time warping (and the involvedenormous energies) is not necessary, providedinertia manipulation become feasible, within theframework of a mass tensor formalism.


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Momentum exchange tetherThis sub-set represents an entire area of research using a spinning conductive and/ornon-conductive tether to throw spacecraft up or down in orbit (like a sling), therebytransferring (or taking) its momentum.

The act of spinning a long tether end-for-end creates a controlled acceleration on theend-masses of the system and a tension in the tether. This spin is manipulated bycontrol of the angular frequency. From this, momentum exchange can occur if anendbody is released at the right point during the controlled rotation. The transfer inmomentum to the released object will cause the tether system to lose (or gain) orbitalenergy, and lose (or gain) altitude (and may require reboosting) or change orbital

planes; and the opposite to happen to the released mass.

When in a magnetic field, such as in low earth orbit, when using an electrodynamictether it is possible to re-boost without the expenditure of consumables. Other schemesinvolve balancing the momentum flow (such as catching and releasing payloads atalmost the same time), or using conventional rocket propulsion or ion drives.


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Graphic of the US Naval ResearchLaboratory's TiPS tether satellite


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Momentum-Exchange/Electrodynamic-Reboost (MXER)tether systems can provide propellantless propulsion for a widerange of missions, including: orbital maneuvering andstationkeeping within Low Earth Orbit (LEO); orbital transferof payloads from LEO to GEO, the Moon, and Mars; andeventually even Earth-to-Orbit (ETO) launch assist. By

eliminating the need for propellant for in-space propulsion,MXER tethers can enable payloads to be launched on muchsmaller launch vehicles, resulting in order-of-magnitudereductions in launch costs. In order for MXER tethers to

achieve their potential in real-world application, several keytechnologies must be developed and demonstrated, includingspace-survivable tethers incorporating both high-strength andconducting materials, technologies for rendezvous with andgrappling of payloads, and techniques for predicting andcontrolling tether rotation and dynamics.


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Icarus Student SatelliteFirst (real) student built, designed, and testedsatellitePart of the tethered satellite propulsion modelWas scheduled to be launched March/May2001Advantageous since it is an instrumentedendmass as opposed to a passive dead weightHelps prove NASAs cheaper/faster/better

solution model


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ProSEDS Propellant-less SmallExpendable Deployer System

Drives current through the tetherDeploys endmass (Icarus)

Icarus (ProSEDS Endmass)Dead weight (~20 kg +/- 0.4 kg)Used to study tether physics

Possible backup in case ofProSEDS failure


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PayloadGPS, Magnetometer provide locationinformation

GPS unit uses the GPS satellite

networkMagnetometer compares the magneticreadings at present location against thecurrent model of the Earths magnetic

fieldTogether, both units provide acomplete measurement of the physicsof the Endmass


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Control and Data Handling

SubsystemsOctagon systems 386 board assimilates the information,sends it to the transmitter

Power: 3.0 W

Memory: 2.64 MB total 2 MB DRAM

512 kB FLASHROM

128 kB SRAM (battery backed)

A/D: 8 channels, 12 bit accuracy

Serial Ports: 2 UART 16C550 chips with RS-232 voltage level Digital I/O: 24 channels (TTL)

Operating Temperature: -40 to 85 C


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Custom C&DH Board performs tasks required specificallyby the Endmass

Analog MUX used to multiplex A/D channels provides 23 totalchannels

Platform for Health Data Collection

Power and Data Connections for all Subsystems

2 4-Orbit Timers in Series

2 21-Day Timers in Parallel

GSE Data Connection GPS Hard Reset Switch


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Power and Electrical SubsystemsPower Distribution SystemSolar Cells

Used to provide main power to theEndmass in day-side of the orbit (8 W)

and to charge the batteriesTotal power provided ~16 W

Batteries (Ni-Cd)Used to provide main power to theEndmass in Eclipse (~8 W)


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Schematic

Transmitter

GPS

Magnetometer

Octagon 386

HealthSystem

Sampled 1/ 2 sec

Connection: RS-232

A/D

3 Analog ValuesSampled 1/sec

Digital bit streamConnection: TTL

Thermistors,Currents, VoltagesSampled 1/min Serial

Port

GroundSupportEquipment

Development andTesting

Connection: RS-232

MUX

on/off

data

SerialPort

DigI/O

MEM

on/off

C&DH System


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TransmitterOutputs assimilated data from theOctagon board @ ~2.247 GHzGround stations at various locations

around the world are set up to receivethe data from this transmitterThe data is then relayed back to theIcarus team for analysis andconclusions


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Payloa

dGPS Receiver Magnetometer

8bits

C&DH

Chip 25 MHz

RAM 2 MB

ROM 512 kB

Transmitter(2.2475 GHz)

Telemetry

Battery

PowerDistribution

Solar Cells

PAA Separatio

nSwitches

ProSEDS

tether

2

Tether attachmentpoint

U of M GSE

SRAM 128 kB

GPS Almanac Data

V = 5.0 V DCI = 11 mA

V = 5.0 V DCI = 185 mA

V = 5.0 V DCI = 650 mA

V = 12.0 VDCI = 400 mA

Power Path

Data Path

Control

4 orbittimer

21 daytimer

System Level Diagram


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Structural Layout

GPS antennawire feed through

Battery box

C&DH and Computerboard component stack

Transmitter

Tether attachhole pattern

Transmitter antennawire feed through

Power Distribution and GPSboard component stack

PAAMagnetometer

GSE Connector


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T=+60 minPower-up,Release

T=~3 hoursTether

Deployment

T=?Instrument

Measurements

T=+1 day

ETDDeployment

T=21+ daysReentry

T=0March/May 2001Delta-II Launch!

Mission Plan


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Students in Lab working on Icarus -

Winter, 2000

Icarus at NASA/MSFC for Vibration

Testing - May, 2000

Icarus in Development


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ReferenceU.S. Patent 6,116,544, "Electrodynamic Tether And Method of UseCP458, Space Technology and Applications International ForumWikipedia.orgWikiflight gearFreelibrary.comIcarus journalNasa.govNasaspaceflight.comSciforum.comGitoriou.orgQuantum potentialLongbets.orgYoutube.com


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