SSTO Design Options

Here's a variation on defining the task ahead and identifying options for the program architecture. Breaking down the major functions of the transportation system to identify the solution space seems to be the best apporach.

1. Introduction

This study defines a plausible program architecture for regularly scheduled commercial passenger flights between Earth and the Moon. The baseline mission is daily flights leaving a single spaceport on Earth, with a single spaceport on the Moon supporting traffic at the other end.

2. Assumptions and Guidelines

• 2.1. All scenarios include use of lunar oxygen as the oxidizer in chemical rockets between Earth and the Moon.

• 2.2. Lunar hydrogen will not be used for fuel for any mission phase.

• 2.3. Primary mission is to provide round-trip passenger traffic between Earth and the Moon.

• 2.4. Returning passenger load is equal to arriving passenger load.

• 2.5. Vehicle design for passenger comfort similar to intercontinental first-class airplane flight with additional accommodation for privacy and sleep periods.

• 2.6. Maximum acceleration for passengers is 3 g. Cargo flights are limited only by structural design and vehicle performance.

3. Mission Architecture Options

• 3.1. Transport Passengers and Hydrogen Fuel to Low Earth Orbit (LEO)

  The solution space encompasses:

  • number of passengers transported to and from the Moon

    options: 10 to 1000
    baseline: 50

  • number of vehicles

    • number of stages for each vehicle
      options: 1, 1.5, 2
      baseline: 1

    • Payload for each vehicle
      options: passengers, fuel, passengers + fuel
      baseline: passengers + fuel

• 3.2. Transport Passengers, LEO to Moon

  The solution space includes:

  • Vehicle Types
    • one passenger vehicle, Earth to Moon to Earth
    • dedicated vehicle, LEO to lunar surface
    • dedicated vehicle, LEO to lunar orbit + dedicated vehicle, lunar orbit to lunar surface
    • dedicated tanker, Earth to LEO
    • dedicated tanker, lunar surface to lunar orbit
    • dedicated tanker, lunar surface to LEO

  • Fueling Options
    • refuel in LEO
    • refuel in LLO
    • refuel on the Moon

    Fueling Options

    	LEO	LLO	LS
    Single vehicle	Required	?	Yes
    Dedicated LEO-to-LS vehicle	No	?	Yes
    LEO-to-LLO vehicle	No	Required	No
    LLO-to-LS vehicle	No	No	Yes

• 3.3. Accommodations on the Moon

  The solution space includes:

  • Permanent facilities on the Moon (the Luna City Hotel)
  • Living accommodations in the transportation vehicle

  Depending on the state of lunar development, it might be economically feasible to start out with tourists using the transportation vehicle as living quarters until permanent facilities are built on the Moon. This ties up the capital resource for a longer time per flight, but it would allow the lunar tourism industry to commence operations sooner.

  If lunar tourism can start several years earlier using this scenario, for many people it will mean the difference between having the opportunity to go to the Moon, and never going there at all. It is likely that the ship would fly with all seats filled, even at $500,000 per ticket.

• 3.4. Transport Passengers, Moon to Low Earth Orbit

  The solution space for this mission phase is identical to the trip from LEO to the Moon.

• 3.5. Braking to Low Earth Orbit

  The solution space includes:

  • Rocket braking to LEO
  • Aerodynamic braking to LEO
  • Aerodynamic braking to Earth's surface

  We need another applicability table here. Obviously, if we're carrying fuel back from the Moon for the next flight out, we don't have an option of heading straight down to the surface.

• 3.6. Transport Passengers, LEO to Earth's Surface

  The solution space includes:

  • Rocket braking to the surface
  • Aerodynamic braking to the surface
  • Rockets + aerobraking to the surface

  In all cases, we assume the vehicle returns to its original launch site on Earth, and is immediately readied for another trip.