nuclear propulsion in space -...
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13 June 2018 Nuclear Propulsion in Space 1
Nuclear propulsion in space
Intercan Technologies
Acknowledgments
13 June 2018Nuclear Propulsion in Space 2
Ad Astra for copyright material on their ion engine
NASA Tech Docs and archives
Jet Propulsion Labs JPL/Caltech
Fraunhofer Institute for Physical Measurement Techniques IPM
Fundamentals
Nuclear has been associated with Fission, Fusion and Weaponry
13 June 2018 Nuclear Propulsion in Space 3
Public associates nuclear with weaponry
Science defines it as “…. Anything that relates to, or pertains to, the nucleus of the atom “
Has Recycled Weaponry Been Used For Space Propulsion ?
The US began Project Prometheus in 2003 with a budget of $430 M but demised it in 2005 …. But why?
13 June 2018 Nuclear Propulsion in Space 4
Russia started it decades ago, abandoned it, recently restarted.
Cite: Cosmos 954 accident over Canada scattering radioactive debris over 100000 sq. km. Some fragments at around 5 Sv/h
Energies in Fusion vs Fission
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Σ x = 1+ x + x2 + x3 + x4 ………………+ x70 +.…+ x75 +.......+ xn-1
2.6 x 10+14 n/cm2/s
Where:x = number of neutrons released
For Uranium x = 2.43 neutrons per disintegration, and can accelerate to 5 neutrons per disintegration.
For Plutonium x > 3.5 neutrons per disintegration and accelerates too.
Using Nuclear Energy ?
The Chain Reaction
in sustained nuclear fission follows a definite
mathematical equation……Geometric Progression:
Make Up of Fission Weapon
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Nuclear Propulsion in Space13 June 2018 8
Explosion Baker July 25, 1946 21 Kilotons
Nuclear Propulsion in Space
Initiation of Blast in Slow Motion
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13 June 2018
TRINITY – first nuclear explosion
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10
"Now I am become Death, the destroyer of worlds."
Robert Oppenheimer, the father of atomic weaponry quoted from the Bhagavad Gita
(Sanskrit) भगवद्गीता
Nuclear Propulsion in Space
Fusion Weapon Triggered by Fission Weapon
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Edward Teller, father of the hydrogen bomb
Nuclear Propulsion in Space
Hydrogen Weapon
13 June 2018 12
From what we have seen …. Neither fission nor fusion are pragmatic methods of propulsion
Pu-238 is used. 1 kg Pu-238; golf ball sized ≡ 22MWh of energy
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Pu-238 cannot sustain a nuclear reaction e.g. in a reactor nor for nuclear weapons
Pu-238 decay produces a bounty of alpha particles. If enclosed in a noble gas, the alpha strips the electrons which then migrate to an anode, producing electricity. The decay heat of the Pu is used to keep the instruments warm. Projected for use in cardiac pacemakers,
space satellites and navigation beacons
Decay heat is 0.56 W/g
560 W/kg
13 June 2018 Nuclear Propulsion in Space 14
Why not use Pu-239Pu-238 β decay to U-234 releases 5.593 MeV per disintegration
Pu-239 β decay to U-235 releases 5.245 MeV per disintegration
Russia and USA stopped producing Pu-238 due to political treaties on nuclear disarmament and non proliferation. Pu-238 has become scarce
How to Make Pu-238
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Pu-238 is obtained by bombarding Uranium-235 with Deutrons (Heavy Water hydrogen).Neptunium-238 results as an intermediate product, which then decays to formplutonium-238. Plutonium-238 decays to Uranium-234 and then further along theRadium decay chain series to Lead-206
Generating Power from Pu-238
Thermoelectric Generator (RTG or RITEG)
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Thermocouples !!!
Used on Curiosity Martian Rover comprises 572 thermocouples. Producing 4410 W using Silicon Germanium that can produce >300 µV/°C.
Thermocouple Outputs
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Type K thermocouple output 46.8 µV/°C. Typical outputs are in region of 1 µA/°C
An RTG Assembly produces 10A - 8.75 A from Silicon Germanium junctions even after several months decay of Pu-238
Conversion rate is 0.12We /Wt
Hence a new material is being researched
Skutterudite Cobalt-Arsenide material named after Skotterud, a
city in Norway, with varying amounts of Ni and Fe
13 June 2018 Nuclear Propulsion in Space 18
Skutterudites with zinc antimonide tested at JPL exhibited higher conversion efficiency
Skutterudite thermocouple electricity generators are also being developed to convert car exhaust heat to electricity to recharge batteries or enhance hybrids.
Volt-Amp relationship of a 32 SkutteruditeThermocouple cluster
Multiple module Skutterudite generator that works up to 500 °C. Source Franhaufer
Also considered to power heart pacers !!
Space Craft Power
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RTG Power for Successful Space Missions
Mission Destination Longevity after BOM
Quantity of Pu-238
BOM Electrical Output
Flight Mass
kg
Operating
Voltage
Internal Ω
Resistance
Galileo Jupiter orbiter 4.2 years
(71000 h)
8.1 kg per
RTG
470 We for two
RTG’s
55.95 30 2.197
Ulysses Sun’s Polar
Mission
4.7 years
(42000 h)
8.1 kg per
RTG
245 We 55.81 28 2.279
Cassini Saturn and Moon
Titan
At BOM
After 16 y
8.1 kg per
RTG
826 We
596 We
56.31 30 2.229
New
Horizons
Pluto and Moon
Charon; then to
Kuiper Belt 2020
At BOM
On-going 9.5 y
orbit Pluto
8.1 kg per
RTG
237 We
191 We
57.91 30 2.229
Acronyms:
BOM: Beginning of Mission. Longevity and hours do not match due to fuel enrichment and what decay had already
occurred.
EOM: End of Mission. Source Bennet & Lombardo etal.
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13 June 2018Nuclear Propulsion in Space 21
Radioisotope Thermoelectric Generators Used On :
Galileo Spacecraft Orbiting Jupiter. One of two RTG’s shown at top
New Horizons Spacecraft flying by Pluto . Moon Charon in background. RTG shown on left
Cassini Spacecraft shown over Titan , a Saturn Moon. Two of three RTGs shown near top
Radiation from Pu-238
Rate of neutrons released from PU-238 is ~5.9 x 103/s per gram
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Equivalent to 0.2 – 0.5 mSv/h in the shown configuration
Gamma dose rate varied from 0.05 mSv/h (twice allowable in nuclear power plants) to 0.10 mSv/h
Not considered damaging for this type of equipment
Nuclear vs Chemical Rockets
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Why Nuclear ?
Introduce Ion Thrusters and Specific Impulse Isp (s)
Comparisons of Ion Thrusters
Engine Propellant Specific Impulse Isp Power kW Thrust mN
NEXT Xenon 4190 6.9 236
Annular Engine Xenon 5000 14 Under test
VASIMR Argon 3000-30000 200 ~ 5000
Hall Effect Bismuth 8000 140 2500
Hall Effect Xenon 2900 75 2900
Dawn Spacecraft Xenon 3100 Solar panels10 kW on Earth
90
Specific Impulse (Isp) is a way of describing the efficiency of a rocket. It represents the impulse, the change in momentum, per unit amount of propellant fuel used. Its units are in seconds (time)
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under test and futuristic
Has 2 gimballed thruster assemblies Logged 51000h ground testing without failure
13 June 2018 Nuclear Propulsion in Space 25Source : NASA Glenn Research Center
NEXT: Nasa Evolutionary Xenon Thruster Ion Engine
VASIMR Engine Variable Specific Impulse Magnetoplasma Rocket
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Hall Effect Thrusters Based on the Lorentz Force
Metallic Hydrogen
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Pressure Comparisons
Location Typical Pressure psi
Sea Level 14.7
Marianna Trench 7 miles salt water8 tons = 17820
Carnegie Institution Diamond Anvil
50 M
Centre of Jupiter 109
Neutron Star 1021
When cooled further it becomes a solid
Used as rocket fuel in its super cold liquid
At intense pressures, >50 M psi it becomes metallic and superconductive
Metalization occurs: 67.4 – 72.53 Mpsi at 5.5 °K
Diamond anvils were used for pressurization
Claimed energy ensity as 270 kJ/cm3 about 35 times more explosive than TNT
Source Harvard University Diaz & Silvera
Still a lab experiment
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RTG
What is the time NOW on Mars ?
http://mars.nasa.gov/msl/mission/instruments/environsensors/rems/
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Thankyou for
Your Attention
13 June 2018Nuclear Propulsion in Space 32
Lengths of videos
Explosion Baker 1:58
Slow motion 0.05
H-weapon 0.36
Spacecraft Power, NASA 3.09
Why nuclear 1:20
VASIMR 1:25
Time on Mars 1:30
TOTAL 10.03
13 June 2018 Nuclear Propulsion in Space 33
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