System Architecture

Strawman Reference Architecture

Launch (Earth Surface to LEO)

 * All launches conducted on FH
 * As many PMs as can fit on launches with other modules will be launched as such
 * Depleted PMs will be jettisoned
 * Additional needed PMs will be launched on dedicated launches
 * Launch LSCM, the pressurized lunar landing vehicle, and PMs needed for descent and TEI, on WSB (Weak Stability Boundary) Trajectory
 * Launch LS to LEO
 * Perform remaining dedicated PMs to LEO launches
 * Launch ERV to LEO with crew

LEO Operations

 * Prior to ERV launch, perform AR&D of LS and all PMs in LEO
 * Launch ERV (noted above) with consumables for LS
 * Dock ERV with LS
 * Perform LS checkout in LEO
 * Replenish LS consumables from ERV-launched supplies
 * Undock from ERV with crew in LS
 * Perform LS TLI into fast trans-lunar trajectory (FTL) (3-4 days travel time)

Trans-Lunar and LLO Operations (LEO to LLO)

 * Pending nominal TLI, await arrival to lunar space (60-100 days travel time)
 * Perform rendezvous between cargo arriving on Hiten trajectory (LSCM, PMs for descent and Earth return, i.e. LSCM stack)
 * Perform automated docking between all descent hardware, while maintaining formation flight with Earth-return hardware outside of collision zone
 * Perform LOI for FTL cases
 * Maneuve ' r LS to rendezvous an ' d dock with earth return hardware
 * Perform docking between LS stack and LDS
 * Transfer crew and additional lunar surface-bound items to LSCM
 * Undock from LS stack

Lunar Descent (LLO to Lunar Surface)

 * Descent burns performed with PM(s), dropped during descent (number as of yet undetermined), completed with DM

Surface Operations (Lunar Surface)

 * See Searching for Subsurface Lunar Water Ice using a Nuclear Powered Rover summary for possible surface operations idea

Lunar Ascent, LLO-LTO Operations

 * LSCM module launches, docks with LS stack
 * Crew transfers to LS
 * LSCM is jettisoned
 * LS stack performs TEI

Earth Arrival, Landing

 * LS aerobreaks upon Earth arrival to circularize orbit, entering LEO
 * LS docks with ERV
 * Crew transfers to ERV
 * ERV undocks from LS, returns to earth
 * LS remains in parking orbit for next mission

Long Term

 * Launch unmanned cargo to lunar surface including habitats and rovers, using additional flights affordable per year above 1 manned mission per year

Stages of Orbit

 * 1) Launch propulsion modules to LEO/GEO/LLO
 * 2) Launch capsule to LEO/GEO/LLO
 * 3) Rendezvous in LEO/GEO/LLO


 * 1) ​ If rendezvous occurs before LLO, perform burn to LLO
 * 2) Descend to lunar surface with capsule-lander
 * 3) Ascend from lunar surface with capsule
 * 4) Perform burn to return capsule to earth (direct injection)

​Required Components

 * 1) Multiple propulsion modules
 * 2) Capsule to support habitation for 35 days (28 days on surface, 7 transit)
 * 3) Lander stage to support capsule

​Key Points of Interest

 * 1) Capsule is used for all habitation
 * 2) Lander stage remains on the surface of the moon (non-reusable)


 * 1) ​ Flexible path may allow us to reuse landers at some point in time
 * 2) All components non-reusable

Stages of Orbit

 * 1) Launch propulsion modules to LEO/GEO/LLO
 * 2) Launch capsule and lunar habitat to LEO/GEO/LLO
 * 3) Rendezvous in LEO/GEO/LLO


 * 1) If rendezvous occurs before LLO, perform burn to LLO
 * 2) Transfer astronauts from capsule to habitat-lander in LLO
 * 3) Descend to lunar surface with habitat-lander
 * 4) Ascend from lunar surface with habitat
 * 5) Transfer astronauts from habitat to capsule in LLO
 * 6) Perform burn to return capsule to earth (direct injection)

​Required Components

 * 1) Multiple propulsion modules
 * 2) Capsule to support habitation for 7 days (transit)
 * 3) Habitat stage to support operations on the lunar surface (28 days, habitable part of lander)
 * 4) Lander stage to support lander habitat

​Main Difference from Previous Architecture

 * 1) Habitat (housing on the lander) is used to sustain astronauts while they complete their lunar mission. The capsule remains in LLO.
 * 2) Reduces landed mass (no heat shield)

Key Points of Interest

 * 1) Capsule is used for transit habitation
 * 2) Lander stage remains on the surface of the moon (non-reusable)


 * 1) Flexible path may allow us to reuse landers at some point in time
 * 2) All components non-reusable

Stages of Orbit

 * 1) Launch propulsion modules to LEO/GEO/LLO
 * 2) Launch surface habitat to LEO/GEO/LLO
 * 3) Launch capsule and lunar habitat to LEO/GEO/LLO
 * 4) Rendezvous in LEO/GEO/LLO


 * 1) If rendezvous occurs before LLO, perform burn to LLO
 * 2) Transfer astronauts from capsule to habitat-lander in LLO
 * 3) Descend to lunar surface with habitat-lander (with surface habitat)
 * 4) Construct surface habitat within “x” days
 * 5) Ascend from lunar surface with habitat
 * 6) Transfer astronauts from habitat to capsule in LLO
 * 7) Perform burn to return capsule to earth (direct injection)

​Required Components

 * 1) Multiple propulsion modules
 * 2) Capsule to support habitation for 7 days (transit)
 * 3) Habitat stage to support operations on the lunar surface (28-x days, habitable part of lander)
 * 4) Surface habitat to sustain astronauts for “x” days
 * 5) Lander stage to support lander habitat

Main Difference from Previous Architecture

 * 1) Habitat (housing on the lander) is used to sustain astronauts while they construct the surface habitat. The capsule remains in LLO.
 * 2) Landed mass increases for the first mission (must bring surface habitat)
 * 3) Surface habitat is now reusable for future missions (must resupply)

Key Points of Interest

 * 1) Capsule is used for transit habitation
 * 2) Lander stage remains on the surface of the moon (non-reusable)


 * 1) Flexible path may allow us to reuse landers at some point in time
 * 2) Surface habitat is reusable

Stages of Orbit

 * 1) Launch propulsion modules to LEO/GEO
 * 2) Launch lunar bus to LEO/GEO
 * 3) Launch capsule to LEO/GEO
 * 4) Rendezvous in LEO/GEO to transfer crew into lunar bus for lunar transport
 * 5) Perform burn to maneuver to LLO
 * 6) Transfer astronauts from lunar bus to habitat-lander in LLO
 * 7) Descend to lunar surface with habitat-lander (with surface habitat)
 * 8) Ascend from lunar surface with habitat
 * 9) Transfer astronauts from habitat to lunar bus in LLO
 * 10) Perform burns to return lunar bus to earth LEO/GEO
 * 11) Rendezvous with capsule in LEO/GEO; transfer crew
 * 12) Return to earth via capsule (lunar bus remains in LEO/GEO)

Required Components

 * 1) Multiple propulsion modules
 * 2) Capsule to support habitation for 1 day (to LEO/GEO)
 * 3) Lunar bus to support habitation for 7 days (transit)
 * 4) Habitat stage to support operations on the lunar surface (28 days, habitable part of lander)
 * 5) Lander stage to support lander habitat

Main Difference from Previous Architecture

 * 1) Habitat (housing on the lander) is used to sustain astronauts during entire lunar stay. The lunar bus remains in LLO.
 * 2) Landed mass decreases back to only the habitat mass
 * 3) Lunar bus is reusable for future missions (must resupply)

Key Points of Interest

 * 1) Capsule is used for LEO/GEO travel
 * 2) Lunar bus is used for lunar transit
 * 3) Lander stage remains on the surface of the moon (non-reusable)


 * 1) Flexible path may allow us to reuse landers at some point in time
 * 2) L unar bus is reusable for future missions

Stages of Orbit

 * 1) Launch propulsion modules to LEO/GEO
 * 2) Launch surface habitat to LEO/GEO (one time)
 * 3) Launch capsule and lunar habitat to LEO/GEO
 * 4) Launch lunar bus to LEO/GEO
 * 5) Rendezvous in LEO/GEO to transfer crew to lunar bus
 * 6) Perform burn to LLO
 * 7) Transfer astronauts from lunar bus to habitat-lander in LLO
 * 8) Descend to lunar surface with habitat-lander (with surface habitat)
 * 9) Construct surface habitat within “x” days
 * 10) Ascend from lunar surface with habitat
 * 11) Transfer astronauts from habitat to lunar bus in LLO
 * 12) Perform burn to return capsule to earth LEO/GEO
 * 13) Rendezvous with capsule and transfer crew
 * 14) Return to earth via capsule (lunar bus remains in LEO/GEO)

Required Components

 * 1) Multiple propulsion modules
 * 2) Capsule to support habitation for 1-2 days (rendezvous with lunar bus)
 * 3) Lunar bus to support habitation for 7 days (transit)
 * 4) Habitat stage to support operations on the lunar surface (28-x days, habitable part of lander)
 * 5) Surface habitat to sustain astronauts for “x” days
 * 6) Lander stage to support lander habitat

Main Difference from Previous Architecture

 * 1) Habitat (housing on the lander) is used to sustain astronauts while they construct the surface habitat. The lunar bus remains in LLO.
 * 2) Landed mass increases for the first mission (must bring surface habitat)
 * 3) Surface habitat is now reusable for future missions (must resupply)

Key Points of Interest

 * 1) Capsule is used for transit habitation to LEO/GEO
 * 2) Lunar bus is used for transit habitation to LLO
 * 3) Lander stage remains on the surface of the moon (non-reusable)


 * 1) Flexible path may allow us to reuse landers at some point in time
 * 2) Surface habitat is reusable
 * 3) Lunar bus is reusable