Options for Each Stage of the Reference Mission

Italicized options are ones not likely to be used.

1. Launch Lunar Transfer Vehicle with its fuel
   Key options:
   • Choice of launcher
   • Separate launches for LTV and fuel
   • Send small robot cameras to moon ahead of manned vehicles

2. Check out the LTV
   Key options:
   • Check out while attached to space station
   • Earth orbit flight
   • Circumlunar flight

3. Launch descent stage, ascent stage with fuel
   Key options:
   • Choice of launcher
   • Man-assisted assembly to LTV vs. automated rendezvous & dock

4. Launch lunar base core module
   Key options:
   • Choice of launcher
   • Crew goes up with hab vs. separate launch
   • Choice of crew transport to low Earth orbit
   • Size of crew (2, 3, 4, 5, 6)

5. Integrate and check out the Artemis stack in low Earth orbit
   Key options:
   • At International Space Station
   • At Mir
   • At Shuttle
   • Without assistance from other spacecraft
   • From our own transportation node in low Earth orbit  (there goes the budget . . .)

6. Artemis stack trans-lunar injection
   Key options:
   • Free return trajectory
   • Direct trajectory
   • Fuzzy boundary trajectory (not a viable option for manned flight)

7. Lunar orbit insertion
   Key options:
   • Free return trajectory
   • Descent orbit trajectory for whole stack vs. separation
   • Choice of landing site

8. Undock and separate
   Key options:
   • Manned vs. automated lunar transfer vehicle
   • Size of landing crew
   • No orbiting vehicle

9. Descent orbit initiation
   Key options:
   • Drop automated cameras with landing beacons ahead of manned craft
   • Separate before or after DOI

10. Meanwhile, lunar transfer vehicle circularizes its orbit around moon
    Key options:
    • Altitude

11. Descent
    Key options:
    • Orbit tracking techniques
      • Landing beacons on surface
      • Inertial navigation
      • Star tracker and lunar map navigation
      • Doppler shift at ground stations for navigation
      • Earth-based radar navigation

12. Landing
    Key options:
    • Choice of landing site
    • Amount of fly-around capability
    • Terrain roughness design specification
    • Methods of photographing the landing
      • Our own little cameras
      • Robot rovers (Carnegie-Mellon)

13. Lunar Surface Operations
    Key options:
    • Length of stay
    • Site survey
    • Low-g demonstrations
    • Geological investigations
    • Equipment for lunar traverse (feet, cart, rover)
    • Lunar mining pilot plant
    • Lunar oxygen pilot plant
    • Amount of material to harvest
    • Type of material to harvest

14. Ascent stage liftoff
    Key options:
    • Size of landing crew
    • Weight of material to return
    • Pressurized vs. unpressurized ascent stage

15. Ascent Stage + LTV rendezvous
    Key options:
    • Choice of active vehicle (LTV or ascent stage)
    • Type of rendezvous equipment (rndz radar?)
    • Type of docking equipment

16. Transearth Injection
    Key options:
    • Drop ascent stage vs. keep it for re-use
    • Drop tanks used to get here

17. Earth orbit rendezvous
    Key options:
    • Rockets
    • Aerobrake
    • Earth atmospheric entry (probably not viable for Artemis)
    • Rendezvous with ISS
    • Rendezvous with Mir
    • Rendezvous with Shuttle
    • Rendezvous with our own Earth orbit transportation node ($!)
    • Rendezvous with other spacecraft

18. Return crew and material to Earth surface
    Key options:
    • Choice of spacecraft