System-Level Technologies Description Strengths/Benefits Weaknesses/Risks Supporting Technologies Information Sources
Advanced Chemical Rocket Pulsed detonation wave engines, Isp improvements, density benefits. Lower risk, Stability, explosiveness, difficulty of control. High temperature materials, Gelled: GRC. Storables: Army,
Systems metallized/slush/gelled propellants, high-energy higher-TRL. Propellants may have other Packaging, handling, propellant manufacturing industrial processes. Redstone. Exotic energetics
density matter (HEDM), metal hydrides, free customers, synergies with industrial processes. concerns. Only modest improvement over (propellants, explosives): intelligence
radical H, flourine, beryllium, tetrahydrogen, Operationally attractive (does not rely on heavy conventional chemical for the effort. community study, Indian Head,
polynitrogen, structural bond energy release ground infrastructure during flight). Pusled- Toxicity/corrosiveness. Generally results in Aberdeen, Sandia. SBER:
(SBER), ionic liquids. detonation: May be useful for reducing higher 'combustion' temperatures. Bridgeman; Aberdeen, Russia.
pressure/heat requirements on turbopumps. Andrews Space DARPA SBIR on
high energy/density rocket fuel.
Metallic hydrogen Large Isp improvements (specific energy 20-fold High risk (not yet synthesized, manufacturing High temperature materials, Isaac Silvera (Harvard)
over H2/O2 combusion), density benefits costs, metastability uncertainty, detonation industrial processes.
control)
Advanced Airbreathing, Combined- Air collection and enrichment system (ACES), Well-studied. Vehicles designed to fly at higher q Few advantages over rocket. Fails against NASA ACES: Uses existing lightweight Dana Andrews
Cycle Systems Scramjets with advanced propellants, ejector and may be more robust/sound in abort modes. metrics. Dry weight, cost higher than a rocket heat exchangers, rocket engines,
scramrocket/air-augmented rocket. Synergy with orbital tether concepts. More with comparable technology. No ground facilities turbine engines. Integrated
flexible operationally. Alchemist ACES: designed to do hypersonic tests leads to an expensive structure/tank/TPS
to improve safety, reliability, ops cost. Lower sortie of development flights. Airbreathing is
GLOW by eliminating LOX at ignition. great for cruise but not acceleration. Becomes
much more difficult after Mach 6. Structures to
contain propellant become unwieldy.
Axisymmetric vehicles are much easier to work
with. Thermal environment more severe.
Nuclear systems Nuclear-thermal rocket: Solid-core, Energy density. Synergy with terrestrial power Radiation. Politics, perceived risk. Decades to Graphite blisk turbines. Radiation
pebble/particle bed, gas core, nuclear "lightbulb." generation, airbreathing cycles (ASPEN). High set up facilities. Issue of containment vs. shielding. High-power density
Fission fragment rocket. thrust and Isp. dispersion of radioactive material during vehicle reactors (for thrust-to-weight
failure. T/W, shielding, safety issues, reusability, improvement). Proximity operations
life of materials. Inability to do development and development.
testing due to treaty issues. Commercial
nonviability: nobody wants it.
Classic Orion: pulsed nuclear detonations. "Berlin airlift" to the moon: massive capability. Minimum bomb size leads to huge vehicles. Unit
numbers of one or two kill the economics.
Political acceptability.
Low-energy nuclear reactions (LENR). No radiation, very-high energy density. Interface is destroyed after a few hours. Possible side effect: metallic H George Miley (UIUC)
"Manufacture as you go" may be an issue. LENR production.
rocket is not favored: you still need a giant H2
tank.
Antimatter: antiprotons, positrons. Positronium 100% mass-energy conversion. Positrons are Antiprotons are expensive. Unknown dry mass Jerry Jackson (Fermilab), Jerry
for storage. cheap (PET scan). implications for antimatter storage. How to use Smith (Penn State)
the gamma rays for propulsion? Low TRL, long
and expensive development, uncertainty of
development cost/schedule/performance.
Inertial-Electrodynamic Fusion (IEF) Possibly fully-enclosed system with tremendous Significant scale-up required. Robert Bussard, et al. EMC2 Fusion
energy potential and minimal neutrons (p+B11, Development Corp.
can be sold as "clean").
Other nuclear concepts: nuclear isomers,
Winterberg: Cold Fast Compression, Mini-mag
Orion
Beamed Power Systems Laser & microwave based. Coil gun firing smart Reusable infrastructure. Synergy with power 1MW/kg of vehicle mass. Whole new class of Astronomy-like adaptive optics. Leik Myrabo (RPI), Jordin Kare,
particles, Myrabo laser lightcraft, lenticular MW transmission applications, weapon uses. safety issues. "Launch window" problem: need to Affordable energy storage to power Kevin Parkin (NASA-ARC).
lightcraft. Microwave/laser thermal heat Microwaves: more efficient end to end, less clear everything in the path of the beam. beam systems. High power density
exchanger. "Direct" propulsion vs. onboard expensive, more available. Lasers: Less Gigawatts of power to the jet. Problems with the beam atmospheric propagation.
thermal or electric conversion. divergence. Wallplug power is cheap. "slew angle," beaming tangentially through the
Decoupling the energy source from the vehicle atmosphere to "turn" the vehicle for orbital
can lead to fewer onboard systems? Synergy insertion (non-axial beam vs. flight path). Issues
with MHD. Rapidly moving technology. intercepting the beam with the vehicle.
Political/treaty issues with a gigawatt laser that
looks like a weapon. Large uncertainty in
atmospheric laser propagation assumptions.
Solitons: Nonlinear medium effects cancel beam Negligible beam divergence over very long Extremely high spatial power densities required
divergence forces. distances. to induce nonlinear medium effects. Major
unknown if solitons are possible in vaccuum/free
space.
MHD Thrust Augmentation MHD accelerators, MHD-augmented rocket Enables large exhaust velocity increase without Electrical energy must be provided, possibly Energy storage, lightweight high- Ron Litchford (NASA-MSFC)
large increase in temperature. beamed energy or very advanced battery power electrical switches, cables
technology. Need high conductivity in the fluid and controls
(ionization, seed, etc.). Cooling requirements:
superconductors at rocket temperatures?
Advanced Field Propulsion Systems Breakthrough Physics TRL 0.
Orbital tethers, space elevator Skyhook eletrodynamic tether, bolos, rotovators, Perform momentum exchange work in space via Length/mass of cable for launch costs, cable Advanced materials: single crystal Michael Wayne, Dana Andrews.
space elevator. the tether, reducing vehicle delta-V failure mechanics, interaction of the tether with diamond, thin-film diamond, BNNT,
requirements. Low recurring cost. "Single stage the atmosphere and electromagnetic space CNT, M5, SK-60.
to tether" vehicle can be half the size of an environment, collision avoidance, reboost
SSTO vehicle, developed and operated with requirements. Launch azimuth limitations.
significant cost savings.
Ground-Based Launch Assist Slingatron, blast-wave accelerator, Cable More benefit to A/B, delta-V only one small piece Cost of StarTram, et. al. infrastructure. Can you "thin water jet" aerospike, energy Sandia study of StarTram. GA Tech
Systems catapult, Argus, ARTS AIAA, Olds stuff, low-g v. really capture the launch market with high-g storage technologies study - Bifrost. Navy EMALS work.
high-g, StarTram, ultra-tall towers. systems? In space infrastructure to receive high- Bushway. New Jersey.
g payloads. Upper limit to acceleration to human
cells. Limitations on launch azimuth. Where do
you build it (NIMBY)?
Electromagnetic launch assist Enables reduced engine mass to be available for Flight rates of 30/yr required to support Energy storage, lightweight high- Navy EMALS, NSW, Lakehurst, NJ.
payload infrastructure operations. Launch azimuth power electrical switches, cables Ken House (NASA-MSFC).
constrained to +/- 60 deg from track azimuth. and controls
Other Key Technologies
Advanced materials: Ultra-High M5 fibers, BNNT, diamondoid materials Factor of 2 mass improvement integrated, use to Limited by min gage and margin requirements, Harris paper. BNNT: NASA-LaRC.
Strength/Temperature-to-Weight get margins/life to enable HRST. Materials damage tolerance. Can we "weave" or mix
Materials providing multiple functions highly desireable: nanotubes/fibers into macroscale materials in
structure, thermal protection, tank insulation. order to realize revolutionary benefits? Minimum
Everyone is a customer for these materials, not gage design often negates weight savings.
just aerospace. Application of revolutionary
materials to conventional rockets can lead to
significant improvements.
CNT (long) Exceptionally high strength, elasticity, and Long, pure fibers not yet available. Industrial processes for mass
electrical conductivity. Potentially high energy production.
storage via Hooke's Law. High conductivity
enables super small and lightweight motors and
magnets (needed for MHD space applications)
Ultra-High-Density Energy Storage CNT-based, Cole fantasy vehicle, flywheels, Rechargable launch vehicles in orbit. Huge Charge and discharge cycles for high flight rate
superconducting magnet energy storage terrestrial applications. Everyone benefits from systems. Can energy storage systems exceed
(SMES), ultracapacitors, sea water propellant. energy storage. the energy density of rocket propellants?
Ultra-Low-Cost Manufacturing Universal automated Manufacturing facility, free
form manufacturing
Artificial-Intelligence-Based
Automated Ground/Mission
Operations
Artificial-Intelligence-Based IVHM
Note: Include life and operatons
labor…not just mass