Tether Boost Facilities forIn-Space Transportation

Robert P. Hoyt, Robert L. ForwardTethers Unlimited, Inc.

1917 NE 143rd St., Seattle, WA 98125-3236+1-206-306-0400 fax -0537

TU@tethers.com www.tethers.com

John Grant, Mike Bangham, Brian TillotsonThe Boeing Company

5301 Bolsa Ave., Huntington Beach, CA 92647-2099(714) 372-5391

TUI/MMOSTT 2

NIAC Funded Tether Research

¥ Moon & Mars Orbiting Spinning Tether Transport (MMOSTT)

¥ Hypersonic Airplane Space Tether Orbital Launch (HASTOL)

¥ Objectives:Ð Perform Technical & Economic Analysis of Tether Transport SystemsÐ Identify Technology NeedsÐ Develop Conceptual Design SolutionsÐ Prepare for Technology Development Efforts and Flight Experiments

to Demonstrate Tether Transport Technology

TUI/MMOSTT 3

Momentum-ExchangeTether Boost Facility

¥ High-strength tether rotates around orbiting control station

¥ Tether picks payload up from lower orbit and tosses payload into higher orbit

¥ Tether facility gives some of its orbital momentum & energy to payload

¥ Tether facility orbit must be restored to enable it to toss additional payloads

TUI/MMOSTT 4

Electrodynamic Reboost

Magnetic Field

CurrentThrust

Plasma Contactors(Hollow Cathode,FEA, Bare Wire)

¥ Power supply drives currentalong tether

¥ Plasma contactors exchangecurrent with ionosphere

¥ Plasma waves close currentÒloopÓ

¥ Current ÒpushesÓ againstgeomagnetic field via JxBForce

TUI/MMOSTT 5

Momentum-Exchange/Electrodynamic-Reboost Tethers:

Summary of Advantages

¥ Tether Boost Facilities Can Provide a Fully-Reusable In-SpacePropulsion ArchitectureÐ LEO ⇔⇔⇔⇔ MEO/GTO

Ð LEO ⇔⇔⇔⇔ Lunar Surface

Ð LEO ⇔⇔⇔⇔ Mars

Ð ETO Launch, in combination with Hypersonic Airplane/RLV

¥ Momentum Exchange + Electrodynamic Tether Can EnablePropellantless Propulsion Beyond LEO

¥ Rapid Transfer TimesÐ 5 days to Moon

Ð 90-130 days to Mars

¥ Operational Tether System Can Be Tested Before Use With High-Value Payloads

¥ Reusable Infrastructure + Low Consumables ⇒⇒⇒⇒ Lower Cost

TUI/MMOSTT 6

¥ Developed Orbital Architecture for Round Trip LEO⇔⇔⇔⇔LunarSurface Transport

¥ Whole System Launch Mass = 30x Payload MassÐ LEO Tether Boost Facility Mass = 13x Payload Mass, Lunar Tether Facility = 17x Payload

¥ 13 Payloads/Year

¥ Incremental Commercial Development Path

Cislunar Tether Transport System

TUI/MMOSTT 7

Rapid Earth-Mars Transport

Payload pick-up

Payload release OriginEscapetrajectory

Interplanetarytrajectory

DestinationInboundtrajectory

Payload release

Payload capture

Patch point

Tapered tether

Loaded TetherCenter of massorbit

Tapered tether

Loaded TetherCenter of massorbit

Patch point

Earth’s gravitationalsphere of influence

Mars’ gravitationalsphere of influence

Sol

INTERPLANETARY TRANSPORT USING ROTATING TETHERS

¥ Reusable Architecture for Round Trip Earth to Mars Transport

¥ Rapid Transfer Times (90-130 days)

TUI/MMOSTT 8

MXER Tethers Included in NASAÕsIISTP Process

¥ NIAC Funded MMOSTT and HASTOL efforts have resulted inMomentum-Exchange/Electrodynamic Reboost Tethers beingconsidered in NASAÕs In-Space Integrated Space TransportationPlanning Process

¥ TUI & NASA/MSFC developed concept designs for Tether BoostFacilities for 4 classes of missionsÐ Microsatellite

Ð 1 mt Payloads

Ð 5 mt Payloads

Ð 10 mt Payloads

¥ IISTP Process evaluated these designs in trade studies for severaldifferent scientific missions

¥ ÒHigh-Risk/High PayoffÓ

¥ MXER Tethers scored well for several classes of missionsÐ High Performance metric

TUI/MMOSTT 9

Tether Architecture forLEO-GTO-LTO-Mars Transport

¥ Tether facility serves as transport hub for multiple destinations

¥ Tether serves as a zero-propellant, reusable, high-Isp, high thrustÒThird StageÓ

TUI/MMOSTT 10

5mt Payload Tether Boost Facilityfor In-Space Transportation Architecture

¥ Reusable In-Space TransportationInfrastructure

¥ Payload Launched to 325 km LEO

¥ Tether Boosts Payload to Elliptical Orbit

¥ Tether Uses Electrodynamic Thrust to Reboost

Tether System Point Design:

¥ Boost 10,000 kg to GTO

¥ Boost 5,000 kg Vehicle to :Ð Highly Elliptical Orbit (C3=-1.9)

Ð Lunar Transfer Trajectory

Ð Escape Via Lunar Swingby

¥ Tether Facility Launch Mass: 63 mtÐ Deploy using 3 Delta-IV-H LVÕs

Ð Retain Delta Upper Stages for Ballast

Ð 200 kW EOL Power Supply for 1 Month Reboost

Analysis of Other Propulsion Technologies withMX Tether Assist:

¥ Delta-II-Class LV Launches 5,000 kg Spacecraft

¥ Tether Boosts Spacecraft to C3Ê=Ê-1.9 km2/s2

¥ High-Thrust Propulsion Systems:Ð Do Injection Burn at Perigee (570 km, 10.62 km/s)

¥ Low-Thrust Propulsion Systems:Ð Use Lunar Swingby to Escape EarthÕs Gravity Well

TUI/MMOSTT 11

Net Payoff: Reduced Launch Costs

To launch 5,000 kg to GTO:

¥ Using Rockets: Delta IVM+(4,2) or SeaLaunch

~ $90M

¥ Using Rocket to LEO, Tether Boost to GTO:

Ð Delta II 7920 (~$45M) or Dnepr 1 (~$13M)

Ø1/2 to 1/7 the launch cost

TUI/MMOSTT 12

LEOððððGTO Boost Facility

¥ Initial Facility Sized to Boost 2500 kg Payloads to GTO

¥ First Operational Capability Can Be Launched on 1 Delta IV-H

¥ Modular Design Enables Capability to be Increased

¥ Top Level Mission Requirements:

99%Payload pickup reliability

15 daysOperational orbit lifetime

100% of tracked spacecraftCollision avoidance

10 years +Mission life

30 daysTurnaround time

< Delta IV/Ariane 5Payload environment

< Delta IV/Ariane 5Release insertion error

GTORelease orbit

300 km equatorialPickup orbit

2500 kg at IOC, can grow to followmarket

Payload Mass

ValueRequirement

TUI/MMOSTT 13

Mass Properties Breakdown

1330.01000.01000.033%11Tether reeling assembly

330.001330.01000.0Tether Deploy & Control

0.540.50.58%11Beacon

0.040.540.5Docking & I/C Subsys

489.9326.6163.350%21PMAD/PCUt

113.590.845.425%21Plasma Contactor (FEAC)

186.0603.4417.4ED Tether Power Subsys

12.9213.8200.9ADCS

7.86.93.513%21transponder

0.97.86.9TT&C

29.426.013.013%21Computer

3.429.426.0C&DH

1.61.40.713%21Transceiver

0.510.50.213%12Comm. antennae

0.22.11.8TFS Net Comm Subsys

0.510.50.213%12Downlink antennae

1.561.40.713%21Downlink Transceiver

0.22.11.8Downlink Comm Subsys

51.345.422.713%21PMAD

54.248.03.013%28PV array drive motors

3289.52860.52860.515%11Power Storage

2014.61782.91782.913%11PV array panels

673.05409.64736.7Electr.Pwr.

680.33401.32721.125%Structure

247.4997.0749.633%Cabling/Harnesses

165.71270.11104.515%1Thermal Control Subsys

23001326710967LEO Control Station

MassMargin

(kg)

Mass withContingency

(kg)

Mass withno margin

(kg)

Unitmass(kg)

MassContingency

Redundancy

QtyControl StationMass: 10,967 kg

Tether Mass:

8,274 kg

Grapple Mass:

650 kg

GLOW: 19,891 kgÐ 15% margin w/in Delta

IV-H payload capacity

Expended Upper Stage

3,467 kg

On-Orbit Mass:

23,358 kg

TUI/MMOSTT 14

Tether Boost Facility

Control Station¥ Solar Arrays, 137 kW @ BOL¥ Battery/Flywheel Power Storage¥ Command & Control¥ Tether Deployer¥ Thermal Management

Tether (not shown to scale)

¥ Hoytether for Survivability¥ Spectra 2000¥ 75-100 km Long¥ Conducting Portion for

Electrodynamic Thrusting

Grapple Assembly¥ Power, Guidance¥ Grapple Mechanism¥ Small Tether Deployer

Payload AccommodationAssembly (PAA)¥ Maneuvering & Rendezvous Capability¥ Payload Apogee Kick Capability

Payload

Total Mass:ÊÊÊÊ 23,358 kgPayload Mass: 2,500 kg

TUI/MMOSTT 15

NIAC Efforts Have DevelopedImproved Tether Analysis Tools

Tether System Design:Ð Tapered tether design

¥ Spectra 2000

Ð Orbital mechanics considerations todetermine facility mass required

Tether operation: TetherSimª

¥ Numerical Models for:Ð Orbital mechanics

Ð Tether dynamics

Ð Electrodynamics

Ð Hollow Cathode & FEACs

Ð Geomagnetic Field (IGRF)

Ð Plasma Density (IRI)

Ð Neutral Density (MSIS Ô90)

Ð Thermal and aero drag models

Ð Endmass Dynamics

Ð Payload Capture/Release

¥ Interface to MatLab/Satellite Tool Kit

TUI/MMOSTT 16

LEOððððGTO Boost Facility

¥ TetherSimª Numerical Simulation (10x real speed)Ð Tether Dynamics, Orbital Mechanics

TUI/MMOSTT 17

Technology Readiness Level

¥ Boeing & TUI Performed TRL Analysis of MXER TetherTechnologies

¥ Many necessary components are already at high TRL

¥ TRL Analysis Indicates Areas for Future Work to Address:Ð Power management subsystem

Ð Thermal control subsystem

¥ Higher power than previously flown systems

Ð Electrodynamic Propulsion Subsystem

¥ Plasma contactors

¥ Dynamics control

Ð Automated Rendezvous & Capture technologies

¥ Prediction & Guidance

¥ Grapple Assembly & Payload Adapter

Ð Some work ongoing in HASTOL Ph II effort

Ð Flight Control Software

Ð Traffic Control/Collision Avoidance

TUI/MMOSTT 18

0

4

8

12

ÆZ

(m

)

16

20

-10 0 10ÆX (m)

Rendezvous

¥ Rapid AR&C Capability Needed¥ Relative Motion is Mostly in Local Vertical¥ Tether Deployment Can Extend Rendezvous

Window

¥ Additional Tether Deployment Under Braking Can Reduce ShockLoads

Payload Capture Vehicledescends towards Payload

PCV DeploysMore Tether PCV pays out tether

and Payload maneuversto dock with grapple

PCV engagestether brake and begins to lift payload

0

0.2

0.4

0.6

0.8

1

0 10 20

Lo

ad

Le

vel

30 40 50

0.1 s braking

5 s braking

10 s braking20 s braking

Time (s)

30 s braking

TUI/MMOSTT 19

Space Debris-Survivable Tether

¥ Micrometeoroids & Space Debris WillDamage Tethers

¥ Solution approach: spread tether materialout in an open net structure with multipleredundant load/current paths

PrimaryLines

SecondaryLines(initiallyunstressed)

0.2 to10's of meters

0.1- 1 meter

SeveredPrimary

Line

Effects ofDamageLocalized

SecondaryLinesTransfer Load Around Damaged Section

TUI/MMOSTT 20

Proposed RETRIEVE TetherExperiment

¥ Candidate SecondaryExperiment for XSS-11

¥ $800K in Initial Developmentfunds from AFRL

¥ Small ED tether system deorbitsµSat at end of missionÐ Activated only after primary

mission completed

¥ Mass: (CBE+Uncertainty): 6.5 kg

¥ DemonstrateÐ Controlled orbital maneuvering

with ED tether

Ð Long life tether

Ð Stabilization of tether dynamics

TUI/MMOSTT 21

µTORQUE: MX Tether to Boost µSat toLunar Transfer or Escape

Launch vehicleplaces primarypayload into GTO

¥ Microsatellite Tethered Orbit Raising QUalification Experiment

¥ Build Upon RETRIEVE to Create Low-Cost Demo of MXER tether technology

¥ Secondary payload on GEO Sat launch

¥ µTORQUE boost microsat payload to lunar transfer or escape

¥ 0.4 km/s boost to payload

¥ Mass-competitive with chemical rocket

µTORQUE deploys tether &microsat above stage

µTORQUE uses EDdrag to spin up tether

µTORQUE releasespayload into lunartransfer/swingby

TUI/MMOSTT 22

µTORQUE on Delta IV

¥ Delta-IV Secondary Payload

¥ ~100 kg weight allocation

¥ Boost ~80kg microsat fromLEO to low-MEO

TUI/MMOSTT 23

Momentum Exchange/Electrodynamic ReboostTether Technology Roadmap

GRASPExperiment

µTORQUEExperiment

2001 2003 2005 201620132010 20352025

ProSEDS

µPET

ED-LEO Tug

LEO ⇔⇔⇔⇔ GTOTether Boost Facility

ISS-Reboost

TerminatorTetherª

Cislunar TetherTransport System

ETO-LaunchAssist Tether

RETRIEVE

NIAC Study

TUI/MMOSTT 24

Opportunities for NASATechnology Development

¥ Expand AR&C Capabilities for Rapid Capture

¥ High Power & High Voltage Space Systems

¥ Electrodynamic Tether Physics

¥ Debris & Traffic Control Issues

¥ Conduct Low-Cost Flight Demo of Momentum-Exchange Tether Boost

Modest NASA Investment in TechnologyDevelopment Will Enable Near-Term SpaceFlight Demonstration

TUI/MMOSTT 25

Contributors

¥ Boeing/RSS - John Grant, Jim Martin, Harv Willenberg

¥ Boeing/Seattle - Brian Tillotson

¥ Boeing/Huntsville - Mike Bangham, Beth Fleming, John Blumer,Ben Donohue, Ronnie Lajoie, Lee Huffman

¥ NASA/MSFC - Kirk Sorenson

¥ Gerald Nordley

¥ Chauncey Uphoff