1. February 18, 2006HYPERION ERAU 1 Interstellar Travel Now

2. February 18, 2006HYPERION ERAU 2 Agenda RFP Proposal Sub-topics

3. February 18, 2006HYPERION ERAU 3 Request for Proposal Under current or near term technology what can be done to send a robotic probe to a nearby star? Define reasonable cost and flight time What is the minimum probe and engine mass? How long from launch until stellar arrival? How much will it cost? Why is this preferred to telescopes?

4. February 18, 2006HYPERION ERAU 4 Issues If this is done via propulsive methods the following are issues -Fuel Energy Density -Specific Impulse -Thrust/Acceleration

5. February 18, 2006HYPERION ERAU 5 Assumptions Consider a probe launched from a C 3 =0 orbit on a fly-by mission of α-Centari Consider vehicle mass fractions of 20000, 2000, and 200 All probes with ΔV’s of less than 0.05c require 6 months of acceleration All probes with a ΔV of more than 0.05c require 18 months of acceleration Trip time is a function of I sp

6. February 18, 2006HYPERION ERAU 6 Flight Time (years) vs. I sp -Rapid interstellar flight requires millions of seconds of I sp -This can only be accomplished via antimatter propulsion, laser accelerated proton propulsion or solar sails -All of the above systems are out of current technical grasp

7. February 18, 2006HYPERION ERAU 7 Flight Time (years) vs. I sp

8. February 18, 2006HYPERION ERAU 8 Flight Time (years) vs. I sp

9. February 18, 2006HYPERION ERAU 9 Case Studies Time of Flight (years) Δ V (%c) MR 20000 I sp (ks)MR 2000 I sp (ks)MR 200 I sp (ks) 500 0.9128.18936.72952.692 200 2.2870.58191.962131.927 100 4.58141.516184.386264.518 75 6.16190.281247.924355.671 50 9.3287.364374.417537.134 25 19586.702764.4351096.649 10 50.61564.5392038.4932924.398 6 91.22816.1713669.285263.918 NEP Fusion Antimatter

10. February 18, 2006HYPERION ERAU 10 Investigated Propulsion Systems Plasma Core Nuclear Thermal Rocket (NTR) Nuclear Electric Propulsion - 10 MW e core or larger - Consider Ion, Hall Effect, MPD thrusters Nuclear Fusion - Different fuel cycles (D-T, D-D, D-He 3+, pB, spin polarized fuels) - Magnetic Confinement Fusion (MCF) - Inertial Confinement Fusion (ICF) - Magnetically Insulated ICF (MICF) - Antiproton Initiated Fusion (AIF) Antimatter Propulsion (beamed core) - proton-antiproton - electron-positron - hydrogen-antihydrogen

11. February 18, 2006HYPERION ERAU 11 Plasma Core NTR - Requires 10 6 K for 20,000 s + I sp - Contamination a problem - Plasma containment a problem -Probably not feasible

12. February 18, 2006HYPERION ERAU 12 NEP -Fission Reactor produces electrical power -Electrical power runs electrostatic or electromagnetic thruster -Can run Ion, MPD, Arc Jets, and Hall Effect thrusters -Very realistic Problems include power processing, grid erosion, high temperature Materials, but it is feasible to build engines at 30,000-100,000 second I sp ’s

13. February 18, 2006HYPERION ERAU 13 NEP Thrusters Ion MPD ~ 3000 – 100,000 s of I sp I sp can depend on propellant I sp can depend on efficiency I sp depends largely on input power

14. February 18, 2006HYPERION ERAU 14 30 ks NEP What input power is required to obtain 30 ks of specific impulse? How much waste heat does this produce? How do we dissipate the waste heat?

15. February 18, 2006HYPERION ERAU 15 100 ks NEP What input power is required to obtain 100 ks of specific impulse? How much waste heat does this produce? How do we dissipate the waste heat?

16. February 18, 2006HYPERION ERAU 16 Fusion Fusion of light elements provides propulsive source of energy Releases ~ 10 14 J/kg

17. February 18, 2006HYPERION ERAU 17 Fusion Fuel Cycles D-T: Low ignition temp. High neutron yield 1 st generation fuel D-D: Large energy yield Thermal radiation D-He 3+ : Large energy yield Thermal radiation Spin Polarized Fuels

18. February 18, 2006HYPERION ERAU 18 Magnetic Confinement Fusion Tokomak -Torodial fields -Polodial field Spheromak -Similar to Tokomak -Slightly higher Q -Slightly higher α -Under Lawson’s criteria all MCF techniques require low ion densities and long burn times -All MCF techniques are very heavy and have no applications as an electrical power producing device - Plasma is ejected as rocket exhaust

19. February 18, 2006HYPERION ERAU 19 Magnetic Confinement Fusion Gas Dynamic Mirror -Similar to a z-pinch -Ions with precise θ escape -Escaping ions produce thrust -Potentially 50-100,00 s of I sp -Very heavy -Potentially near term if it burns D-T mixture

20. February 18, 2006HYPERION ERAU 20 Inertial Confinement Fusion -Particle beams or lasers compress fusile targets -Magnets must contain plasma for short time frames -Drivers are very heavy must be ~1.6 MJ -Higher Q’s than MCF -Higher α than MCF -High ion densities (neutron star), short confinement time - If weight can be negated this has serious potential in propulsion!!

21. February 18, 2006HYPERION ERAU 21 Magnetically Insulated ICF -Tungsten or gold surrounds target pellet -Low thermal impulse on tungsten shield -Produces transient magnetic field -Reduces need for magnets -Ablated Tungsten reduces I sp -Drastically reduces mass of drivers and electromagnets!!

22. February 18, 2006HYPERION ERAU 22 Antiproton Initiated ICF Muon Catalyzed Fusion -Antiproton annihilation creates μ-mesons (muons) -muons displace electrons around nucleus -must occur at low energies (1200 – 1600 K) -no or little need for drivers -combined with MICF makes a lightweight engine Requires nano-grams of antiprotons

23. February 18, 2006HYPERION ERAU 23 Antiproton Initiated ICF Antimatter Initiated Micro-Fusion/Fission -Antiprotons induce U 238 fission -Released neutrons help compress fusion fuel -Larger α than muon catalyzed fusion -I sp ~ 50,000 s – 1,000,000 s

24. February 18, 2006HYPERION ERAU 24 Antimatter Propulsion -Highest performance under the laws of impulse and momentum -Requires kilograms of antimatter which is not yet available -Offers Isp near the theoretical limit (30.6 x 106 seconds -The only hope for rapid robotic or manned interstellar propulsion

25. February 18, 2006HYPERION ERAU 25 Antiproton -~35% of annihilation energy is lost to massive particles -Requires 2 km long nozzle -Large radiation levels due to pions and muons

26. February 18, 2006HYPERION ERAU 26 Positron -Uses momentum from 0.511 MeV photons -Requires reflection of high energy photons -Positrons easier to produce than antiprotons - Very high burnout velocities

27. February 18, 2006HYPERION ERAU 27 Investigation Questions Does the technology exist now? If not can it be developed in 15 years assuming unlimited funds? Or can the system not be developed with current physical understanding?

28. February 18, 2006HYPERION ERAU 28 Investigated Parameters What is the system mass? What is the system thrust? What is the system I sp ? What is the fastest the system can reach α- centari? What is the systems TRL now? What is the cost of developing this system? What is the cost of launching this system?

29. February 18, 2006HYPERION ERAU 29 Investigated Parameters What is the cost of transferring the craft from LEO to C 3 =0? (assume the use on an NTR) What the minimum engine mass?

30. February 18, 2006HYPERION ERAU 30 Probe Design What are the data transfer signal requirements for transmitting over 4.56 ly? - beam vs. isotropic signal - S/N ratio - Transmission Power - Pointing accuracy What are the thermal control, attitude control, and navigation requirements - The stars will not be in the same place to use star trackers What are the total power requirements for the probe? - Do we need an onboard fission reactor or can we shut down the craft during flight and use solar arrays when it arrives near its target, or even use batteries that only last 15 minutes?

31. February 18, 2006HYPERION ERAU 31 Probe Question How does the info. from the previous slide drive the probe mass? What is the craft dry mass when the probe mass is combined with the engine mass? At MR’s of 20,000, 2000, and 200 what is the total craft mass for each case, when propellant is added to the dry mass?

32. February 18, 2006HYPERION ERAU 32 Questions ???