241 – Electric Propulsion of Spacecraft

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Guest: Jose Gonzalez del Amo     Host: Markus Voelter    Shownoter: Andy Joiner

During my visit to ESA‘s ESTEC last fall, I talked to Jose Gonzalez del Amo, who is the head of the Electric Propulsion Lab. We discussed the basics of electric propulsion, the pros and cons compared to chemical engines, different engine styles and their use cases, as well as the work ESA performs in the lab.

Introduction

00:03:15

Electric propulsion | Jose Gonzalez Del Amo | Head of Electric Propulsion Section | ESA Propulsion Lab Manager (ESA - European Space Agency)  | Chemical propulsion | Aerothermodynamics | Numerical modelling | Chemical rocket propellant | Bipropellant | Oxidizer | Reductant | Thrust | Solar panels | Ion engine | Rocket equation | Specific impulse (exhaust velocity / g) | Chemical exhaust velocity typically 3000m/s | Ion engine exhaust velocity typically 30000m/s | Thrust = mass flow rate x exhaust velocity | Higher exhaust velocity requires less mass for same thrust (GTO - Geostationary transfer orbit | GEO - Geostationary orbit)  | Transfer 4000kg satellite from GTO to GEO requires approx. 2000kg chemical or 300kg electric propellant | Transfer takes approx. 2 weeks using chemical vs 3-6 months using electric propulsion | Launch 2 satellites for the price of 1 with electric propulsion | Electric propulsion still requires chemical propellant | Solar sails | Xenon | High atomic mass | Low valance energy | Easy to ionize | Easy storage

Electric vs chemical propulsion

00:10:34

Save propellant mass | Station keeping | Inter-planetary travel enabler | BepiColombo | Controllability | LISA | Gravity waves | Dark matter | Lagrange point | Solar pressure | Laser interferometry | Accelerometer | GOCE in low orbit (NGGM - Next Generation Gravity Mission)  | 200km separation | Low absolute thrust of electric propulsion | SABRE rocket engine | Flywheels (reaction wheels) | Station keeping | Magnetic moment | Euclid | Thrust ranges (1μN - ~2mN (LISA))  | Ion engine 1mN to 20mN (GOCE) (Station keeping 40mN - 80mN (Telecoms))  | Orbit transfer 5kW: 250mN | Dual purpose engines | Off-the-shelf products vs custom build

Engine types

00:27:36

Electrostatic | Ion Engine | 30000 m/sec exhaust velocity | 30 W/mN | FEEP | Electrothermal | Resistojet | Arcjet | Electromagnetic | Hall effect thruster | 20000 m/sec exhaust velocity (80mN - 250 mN thrust)  | 20 W/mN | Used for many years | Magnetoplasmadynamic thruster | OneWeb | 900 satellites | Low orbit for good latency | Hall effect/ion engine | Deorbit | Hall effect thruster | Ion thruster | Kaufman (ion thruster) | RIT (ion thruster) | Plasma | Helicon thruster | Monte Carlo simulation | Empirical modelling

In the lab

00:57:00

Vacuum chamber | Roots pump | Turbomolecular pump | Cryogenic panels | Adsorb | Data acquisition | Plasma diagnostics | Langmuir probe | Plasma potential | Double charged ion | Seismic block 280 tonnes | Measure thrust using a balance | Passive isolation | Capacitive displacement sensor | Laser interferometry | Active isolation | Valve testing | Water hammer | Investigate engine interference with satellite operation | SMART-1 | 375Kg satellite with Hall effect thruster | 18 months from GTO to moon using 85Kg propellant

ESA

01:09:05

Originally design & manufacture | Currently supporting industry testing & experiments | Satellite project support & verification | Liquid metal propellant for FEEP | Graphite ion impact zone | 4x better erosion coefficient compared with stainless steel | Water cooled to freeze ions | Change engine control parameters to optimize efficiency when eroding | Qualification tests can last 20000 hours (> 2 years) | Typical tests last 5 hours to 2 days | Plume characterization | Balances to measure center of mass | Development of diagnostics | Team of 10

Esoteric propulsion

01:23:17

Bending space-time | Miguel Alcubierre | Time to market | Nuclear-thermal propulsion | Nuclear-electric propulsion | Project Daedalus | VASIMR | Antimatter propulsion | Budgets | Nonmilitary work | Propellant storage | ECR | ESA Funding (GSP - General Studies Program | TRP - Technology Research Programme | GSTP - General Support Technology Programme)  | Advanced Concept Group | Ariadna