What's ahead in space exploration: Potential roles for the INL and the CSNR

Steven D. Howe, Ph.D.Steven D. Howe, Ph.D.Director Director

Center for Space Nuclear ResearchCenter for Space Nuclear Research

7/17/077/17/07

We shall not cease from exploration, We shall not cease from exploration, and the end of all our exploringand the end of all our exploring

will be to arrive where we startedwill be to arrive where we startedand know the place for the first timeand know the place for the first time

--T.S. EliotT.S. Eliot

Tangible BenefitsTangible Benefits Sulfur volcanoes on Io around Jupiter-Sulfur volcanoes on Io around Jupiter-

Planetary geology, ionosphere of Jupiter, Planetary geology, ionosphere of Jupiter, magnetosphericsmagnetospherics

Seas of methane and shorelines on Titan Seas of methane and shorelines on Titan around Saturnaround Saturn Alternative atmosphere; meteorology; xeno-Alternative atmosphere; meteorology; xeno-

chemistrychemistry

Ancient ocean beds on MarsAncient ocean beds on Mars Geology; atmospheric decay; early life?Geology; atmospheric decay; early life?

Intangible BenefitsIntangible BenefitsFinding an ocean on EuropaFinding an ocean on Europa

Demonstrating US technological Demonstrating US technological capability by sending humans to Marscapability by sending humans to Mars

Seeing the lights of a Lunar base each Seeing the lights of a Lunar base each nightnight

Motivating more students to pursue Motivating more students to pursue math and sciencemath and science

Radioisotope Thermoelectric Generator (RTG) Radioisotope Thermoelectric Generator (RTG) have been used since the Apollo dayshave been used since the Apollo days

Pu-238Pu-238 Non-weaponizableNon-weaponizable 87.7 year half-life87.7 year half-life Alpha decay plus gamma raysAlpha decay plus gamma rays

Heavily encapsulatedHeavily encapsulated Qualified against accident scenarios- fire, impact, Qualified against accident scenarios- fire, impact,

explosionexplosion 6-8% conversion efficiency6-8% conversion efficiency No moving partsNo moving parts Around 200 kg/kWeAround 200 kg/kWe Continuous powerContinuous power

INL currently plays a key late-stage role INL currently plays a key late-stage role in RTGs for space missionsin RTGs for space missions

INL is responsible for final INL is responsible for final assembly and testing of assembly and testing of Radioisotopic Radioisotopic Thermoelectric Generators Thermoelectric Generators (RTGs)(RTGs)

The New Horizons mission The New Horizons mission to Pluto – the highest-to Pluto – the highest-priority exploration mission priority exploration mission of the decade – depended of the decade – depended on INL fabricationon INL fabrication

Radioisotope Power Systems (RPS)Radioisotope Power Systems (RPS)

Current RTGs are simple, robust, Current RTGs are simple, robust, and proven technologyand proven technology

Pu-238 running outPu-238 running out CSNR is currently examining CSNR is currently examining

possible alternative isotopes and possible alternative isotopes and new materials to ensure new materials to ensure immobilization in accident immobilization in accident scenariosscenarios

INL has facilities to fabricate new INL has facilities to fabricate new RPS systemsRPS systems

Current design study:Current design study: Using Using RPS sources for space power RPS sources for space power and for long duration (>2yr) and for long duration (>2yr) Remotely Piloted Vehicles for Remotely Piloted Vehicles for planetary observationplanetary observation

Radiation DosesRadiation Doses

What is your average mREM dose?What is your average mREM dose? 360 mREM/year360 mREM/year

A nuclear power plant worker can receive up to: A nuclear power plant worker can receive up to: 5,000 mREM/year5,000 mREM/year

What is an astronaut’s dose?What is an astronaut’s dose? 1,000 mREM/week1,000 mREM/week

Energy Densities of Known SourcesEnergy Densities of Known Sources

ReactionReaction Specific Energy (MJ/kg)Specific Energy (MJ/kg)

ChemicalChemical 7-107-10

Fission (100%)Fission (100%) 71E0671E06

Fusion (100%)Fusion (100%) 750e06750e06

AntimatterAntimatter 90000e0690000e06

NTR was developed and proven in the NTR was developed and proven in the Rover/NERVA programs in the 1960sRover/NERVA programs in the 1960s

Pewee operated at Pewee operated at 2550 K for 40 minutes 2550 K for 40 minutes at 503 MW at 503 MW

The engine weighed The engine weighed 5000 lb and would 5000 lb and would have produced a have produced a thrust of 15,000lbsfthrust of 15,000lbsf

Pewee was Pewee was envisioned as an envisioned as an orbital tug to support a orbital tug to support a Lunar baseLunar base

CSNR Summer Fellows Study results-CSNR Summer Fellows Study results-NTR-based ESAS ArchitectureNTR-based ESAS Architecture

Lunar Surface Payload vs. Number of CaLV Launches

0

2

4

6

8

10

12

14

16

0 100 200 300 400 500

Lunar Surface Payload (mT)

Nu

mb

er o

f C

aLV

Lau

nch

es

Chemical

NTR

Systems Nuclear Auxiliary Power (SNAP-10A) Systems Nuclear Auxiliary Power (SNAP-10A) ReactorReactor

650 We (45 kWt)650 We (45 kWt) Satellite malfunction after Satellite malfunction after

43 days43 days U-ZrHU-ZrHxx fuel (93% fuel (93% 235235U)U) HastelloyHastelloy®® N cladding N cladding Be reflector rodsBe reflector rods BB44C control sleevesC control sleeves NaK coolantNaK coolant ThermoelectricThermoelectric 435 kg reactor mass435 kg reactor mass

Experimental Criticality Benchmarks for SNAP 10A/2 Reactor Cores,A.W. Krass, K.L. Goluoglu, ORNL/TM-2005/54, April 2005.

Jupiter Icy Moons Orbitor (JIMO)Jupiter Icy Moons Orbitor (JIMO)

7 yrs to Jupiter, 11 yrs to 7 yrs to Jupiter, 11 yrs to first sciencefirst science

Nuclear reactorNuclear reactor 100-150 kWe100-150 kWe Estimated mass= 11,820 Estimated mass= 11,820

kgkg length of a football fieldlength of a football field Mass chemical stage to Mass chemical stage to

escape earth = 12,000 kgescape earth = 12,000 kg Specific mass = 100 Specific mass = 100

kg/kwkg/kw

EuropaEuropa

Hydrothermal vents exist on Earth on the bottom of Hydrothermal vents exist on Earth on the bottom of the oceansthe oceans

Diverse life exists at the vents that has never seen Diverse life exists at the vents that has never seen the sun and survives on a chemically based bio-the sun and survives on a chemically based bio-spheresphere

Recent evidence suggests that life on Earth may Recent evidence suggests that life on Earth may have developed on such vents first over a billion have developed on such vents first over a billion years agoyears ago

Similar vents may exist on EuropaSimilar vents may exist on Europa Tidal forces may have heated the Europa crust Tidal forces may have heated the Europa crust

enough to melt an ocean under the iceenough to melt an ocean under the ice Conceivably, life may have developed in the Europa Conceivably, life may have developed in the Europa

ocean alsoocean also

Thanks to James Cameron and Thanks to James Cameron and Earthship ProductionsEarthship Productions

To Paraphrase:To Paraphrase:

Developing a new propulsion technology to travel to Developing a new propulsion technology to travel to the outer planets--the outer planets--

$2B$2B Building a new probe using radioisotopes to penetrate Building a new probe using radioisotopes to penetrate

10 miles of ice--10 miles of ice-- $200M $200M

Seeing the looks on the faces of children around the Seeing the looks on the faces of children around the Earth as they see the first pictures of a new life form in Earth as they see the first pictures of a new life form in an ocean on another world--an ocean on another world--

Priceless Priceless

Our Reach Must Exceed Our GraspOur Reach Must Exceed Our Grasp

The goals of the CSNR and INL are to The goals of the CSNR and INL are to help the country extend its reach as far as help the country extend its reach as far as technologically possible to see what technologically possible to see what marvels, as yet unknown, will come back marvels, as yet unknown, will come back in our grasp.in our grasp.

SummarySummary Nuclear technologies have been used in the US space Nuclear technologies have been used in the US space

program from the beginningprogram from the beginning

All missions beyond Mars have been enabled by RTGsAll missions beyond Mars have been enabled by RTGs

Nuclear rockets could enabled a human mission to Nuclear rockets could enabled a human mission to Mars to be completed within 500 days totalMars to be completed within 500 days total

Fission power will be required for the surface of Mars Fission power will be required for the surface of Mars for human supportfor human support

New alternative isotope power sources may enable New alternative isotope power sources may enable unique science missions to map other planetsunique science missions to map other planets

The CSNR Summer Fellows program is successfully The CSNR Summer Fellows program is successfully examining innovative technologies for spaceexamining innovative technologies for space