Spherical underground Mars colony by Michel Lamontagne

One of the weak spots for any domed human colony on Mars would be the enormous pressure difference needed between the higher interior pressure suitable for humans (~ 1 bar) and the near-vacuum exterior pressure of the Martian atmosphere (0.004-0.011 bar). The dome for such a structure should have heavy anchoring deep underground. But there is a much simpler solution - a spherical hermetic structure mostly underground where only the tip of the sphere (visible as a dome) is located above the ground level. Sphere is the strongest geometric shape for containing internal pressure and the structure can be kept in place by the mass put inside the sphere.

Canadian design engineer Michel Lamontagne has created two concept drawings for such a colony where there is only a domed park above the ground level and all the rest of the colony is located below the ground level with a vertical central opening for natural lighting:

The geodesic surface dome is subdivided into small panes for easier replacement and safety:

SpaceX Starship interior concept for 100 passengers

NASASpaceFlight.com forum members Ace (Rick Kiessig from New Zealand) and lamontagne (Canadian design engineer Michel Lamontagne) have created a concept for the interior layout of SpaceX's 100-passenger Starship (the passenger capacity goal stated by Elon Musk). Therefore this concept isn't meant for the first crew Starships on Mars used as temporary habitats for the first few years. For those first Starships Michel Lamontagne has created a separate concept.

The design divides the living space into 7 decks, labeled A to G, from the bottom-up. There are two openings between decks, offset slightly from one deck to the next, to reduce the risk of accidents related to trying to "fly" through multiple decks while in zero-G. There are removable rails around the openings, to prevent accidental falls while on Earth or Mars. All decks have a 2.2m high living space, except Deck G, which is 2.16m high. The blue bars in some areas are examples of hand and foot holds, like they use on International Space Station (ISS).

The floors are shown with hexagonal tiles, to indicate a system that will allow wall partitions and other items to be attached or removed to meet the tastes and needs of passengers.

Deck A has the gym, an external airlock, some storage space, and a couple of toilets:

• ISS found a need for 2+ hours of exercise per day to avoid bone and muscle loss. Multiplied by 100 people, that requires 10 exercise machines. Note that several of them are mounted on the walls.
• Making full use of walls and ceilings for living space is a theme of this design, since there's no "down" in zero-G.
• The airlock allows access to the outside of the ship during flight, in case of a need to make inspections or minor repairs, and to support landing in places without pre-existing ground infrastructure.

Possible SpaceX Starship Mk 1 propellant tank layout by Michel Lamontagne

SpaceX's Starship Mk 1 prototype, being built at company's Boca Chica launch facility in South Texas, is seeing some rapid development in recent days (prior to Elon Musk's promised update on September 28). New hardware is being attached to the prototype and we can start some educated guesses of the final Starship Mk 1 design which will differ quite substantially from the Starship renders SpaceX provided as recently as in May.

Canadian design engineer Michel Lamontagne has posted his speculative graphics of the possible Starship Mk 1 propellant tank and fin layout on NASASpaceFlight.com forum (where he is known as lamontagne). More of his spaceship renderings here.

Images from the construction site indicate the header tanks (meant for propellant needed for landing) are installed into the front cone of Starship Mk 1:

Speculative internal layout of SpaceX Starship by Michel Lamontagne

In the result of a discussion on NASASpaceFlight.com forum about possible internal layout of SpaceX's first crewed Starship bound for Mars Canadian design engineer Michel Lamontagne (on the forum known as lamontagne) has came up with graphics of his version for Starship's possible internal layout. More of his spaceship renderings here.

Observation / galley deck:

SpaceX downscaled ITS spaceship comparison

Fan vision of possible SpaceX's scaled down version of the ITS cargo spaceship (for 9m booster) compared with the original ITS crew spaceship (for 12m booster), Space Shuttle, Orion and Dragon; created by NASASpaceFlight.com forum member, Canadian design engineer Michel Lamontagne. More of his spaceship renderings here.

We will learn the actual SpaceX design for the scaled down version of the Interplanetary Transport System (ITS) only during Elon Musk's presentation at the 2017 International Astronautical Conference in Adelaide, Australia, September 29.