Starships to Mars

Elon Musk founded SpaceX to "make Earth Life multi-planetary" and "to insure that humanity doesn't die out from something like the giant asteroid impact that killed the dinosaurs". His passion is Mars, and that passion fueled his creation of Space Exploration Technologies (SpaceX); he was shocked to learn that NASA did not have a program for Mars colonization, or even a crewed Mars mission, at all. 

His BFR concept predated the Falcon 9 (per "Elon Musk" by Ashlee Vance, 2015), but the success of the Falcon 9, and it's demonstration of booster landing and reuse (successfully landing Falcon 9 boosters over 500 times since that first success on 22-DEC-2015) are unprecedented. Like Elon also said, "Rockets should land like they do in science fiction": gracefully and without parachutes. The BFR (now lovingly called the "Starship Superheavy") will soon be landing both the booster and the spaceship, essentially ready to refuel and fly again. And that ability makes his Mars colony plans much more feasible.

Note that Elon Musk has long talked about sending thousands of Starships to Mars, most containing just equipment and supplies, and some carrying people: colonists to build a new world. He has shown pretty images of cities on Mars, and hopes to have a million people there by 2050! 

However, SpaceX expects to be the transport, not the total solution. They hope and expect that others will solve the problems of surviving (and thriving) on Mars, including technologies for mining, drilling for water, capturing CO2, Nitrogen, and Argon from Mars' atmosphere, converting some of those into methane and oxygen to fuel ships returning to Earth, and the rest into farms, and buildings, and everything else needed to support a growing industrial civilization on Mars.

That will take a LOT of effort, by a great many people and businesses and governments on Earth as well as on Mars.

First SpaceX Mars Landing Mission

The first mission will be a test mission, perhaps 4 or 5 Starships, unmanned, to prove the ability to land. There may be a crew of Tesla Optimus robots (will we call them "robonauts"?), probably some Cybertrucks for exploration and support, and possibly some heavy equipment for excavation and regolith moving, and importantly, access to water (drills? pipes? holding tanks?). Elon has stated that he wants to start producing LOX and liquified Methane to fuel return Starships, and that is a likely target for his robonaut crew! Of course, they'll need to deploy an array of solar panels, but at least the robonauts won't need to worry about radiation, or the near-vacuum conditions, although I'll wager the cold will be a consideration, especially for their internal batteries. If I was Elon, I'd send a bunch of extra robonauts with cameras to video everything - they would serve as spares, and the publicity would be incredible.

Since that first mission will be to prove a point, and to do some initial up-front work, and possibly to establish a fuel depot, the configurations of the Starships won't be appropriate for colonists. No need for farms, or housing, or any of the other things that are needed for human habitation.

That will come on the ... 

Second SpaceX Mars Mission: First Colonists

The first priority will be surviving! Mars has a shortage of liquid water, breathable air (oxygen and nitrogen on Earth), radiation protection, meteorite shielding, and, of course, food! We'll need to build safe shelters, and grow our own food (recycling CO2, water, and nutrients into food and oxygen) almost from day one. That first resupply mission won't arrive for 30 months (from this mission's Earth launch, so we have to plan on a 900 day, plus some, for emergency everything)! So we'll probably want emergency stores of food for at least that long, and have triply redundant equipment to manufacture oxygen and recycle water, at the very least, not to mention solar panels and batteries to keep the lights on and the pipes thawed!

That first mission has a vital purpose: (a) to survive and communicate back to Earth, and (b) to find the resources needed to make the colony viable (#1: water, lots of water; #2: location to live, #3: location of vital long-term resources such as regolith, building materials, metal ores, hopefully nutrients such as the P and K of NPK so those don't have to be transported from Earth. The "N" is in the air, comprising 2.7% or so, by volume.) 

That "survive" task has multiple components, including deploying solar panels and batteries to produce a power supply to light the lights, warm the air, operate the pumps, illuminate the plants we need for food, oxygen, etc.). 

While the colonists can live in the Starships that brought them to Mars, at least for a while, they need to unload supplies and set up camp. Build the habitats, the farms, the factories, the whatever.

It also includes radiation protection: we probably need to get underground ASAP. The easiest way to do that is probably by building the colony on the surface, and using bulldozers to push a bunch of Mars regolith on top to block radiation and meteorites. A couple of meters should do the trick. We don't want to depend too much on Mars dust, as it tends to blow away, but even coarse sand should stay in place, if we can find it!

Considerations for Colonists

There are two main considerations concerning the colonists on the first manned mission to Mars.

First, how many? Elon has stated several times that the first crewed mission would involve about 4-5 Starships carrying about a dozen people and many tons of supplies. He has also stated that the next mission might send about 20 colonists, and the next about 100, and the next about 500.

Second, what will the crew look like? Everyone agrees that all crew members will be trained in multiple areas to provide, if nothing else, some level of backup / redundancy.

My own models send 8 people per Starship, probably on two Starships, with more Starships carrying supplies. Note that the skills of each Starship crew should be well distributed, to prevent a vital loss of function if one fails to land successfully. That goes for the cargo, as well: no one ship should carry the only one of some vital component (such as solar panels or battery packs).

The journey to Mars takes about four months (assuming arriving using aerobraking to slow down to land), and lots of things can go wrong and it is smart to have a broad set of skills represented on-board so you can fix things. Or people. Here is a set of skills, needed on board and on Mars:

1. Medical
2. Food (preparation, planning)
3. Agriculture (mandatory on Mars, useful on board as we can recycle CO2 by growing 25% of our calories as veggies, plus have a running start when we finally arrive on Mars)
4. Electrical (someone to keep the lights on, the fans blowing, the water running)
5. Electronic (maintain and operate the computers & communication equipment)
6. Air (not needed on Earth but in Space and on Mars someone needs to monitor and maintain proper air pressure, temperature, and contents, keeping O2 up and CO2 down). Think HVAC technician with a PhD!
7. Water (someone needs to monitor and maintain the water supply, even finding it on Mars!) Is this a plumber with a PhD?
8. Recycling (waste collection & recycling, cleaning & laundry, ?police and fire services?)
9. Housing & Construction (on Mars, we even have to build the farms!)
10. Exploration & Mining
11. Manufacturing (metals, plastics, cellulose, & products made from them (including toilet paper))!
12. Planning & Government & Administration

The percentages of each we'll need will be different in the initial, early, and later years of the Colony. Agriculture, food prep, waste, & recycling will dominate early, as will housing & construction as long as the Colony is growing rapidly. Mining is likewise more resource-intensive in the early years, as are medical services (1/3 doctors, 2/3 nurses). In the long term, occupations will tend toward parity with the US Census which reported 12% manufacturing, 10% agriculture (including food prep, waste & recycling), 6% services (food, laundry, cleaning, financial, etc.), and 5% medical. If those numbers seem low, consider that in a large (but still growing) economy, 8.6% of the population are infants, 23.6% are students, and 17.2% are retired: essentially half of the population is working, half not!

There is another, third, important consideration: we are sending colonists, not scientists & explorers. A "colony" differs from an "outpost" by a simple distinction: families. If you aren't having children, you are in an outpost, and probably don't intend to spend your life there. Families are different. You have children and want a long term future for them. Toward that end, I believe that ALL "colonists" should initially consist of (fairly) young married couples, not sterile, and intending to have children. The "married" part of that statement is intended to reduce stress, as there will always be a lot of that on Mars! I don't object to gay and lesbian couples, as long as the women plan to have their fair share of the children (and the men can contribute their own share of child care and of DNA for genetic diversity). Note that genetic diversity is vital, in the long term. But healthy DNA is also important, so we may want to exclude some potential colonists on the basis of their genetics. Having said that, there may be some conditions where life on Mars is easier for those with certain mutations: bad backs, for example!

Considerations for Starships

Starships need to safely transport crew and supplies to the surface of Mars. 

For the journey to Mars, the spacecraft must provide comfortable living conditions, breathable air, drinkable water, edible food, and deal with the waste products of humans! Communications and entertainment and exercise may just be icing on the cake. Somewhat debatable is gravity: if the Starship does not provide gravity (such as by having two Starships tethered and spinning end-over-end), then there will be a necessity for significant exercise, and toilets, food prep, and bathing facilities that can operate in zero G. Accidents (crumbs, water spills, etc.) do not self-organize on the floor, but rather head for wherever they can be the most troublesome (such as electronics).

Personally, I think that artificial gravity (possibly at Mars' 38% G) is important, if for no other reason than the same toilets, showers, and food prep/eating tools will work on the Starship in space and on the ground at Mars. And people won't get space sickness! And won't suffer permanent damage to their eyes! And so many other things we see in astronauts returning to Earth after a long stay on the ISS.

Once landed on Mars, more challenges remain: 

1. Colonists will need a way to get themselves and their supplies down to the surface. Elon has described a crane/elevator to provide transportation from the Starship payload bay down to the surface and back, but we have few details.
2. Colonists will need a place to live, temporarily, while they build new homes on Mars. This implies that the layout of the Starship should be designed for living, not only for the months of the journey, but for the first months on Mars.
3. The Starship must maintain a substantial air pressure, but Mars is essentially a vacuum. Therefore, we'll need an airlock, or two, to keep the Starship livable while it is being unloaded. We'll also need spacesuits (or at least Mars suits) for every colonist. This may also mean that the individual modules may need to be pressure-tight (or vacuum safe) during the transition from on-board to on-planet. Alternatively, the transport container that carries the modules itself might provide pressure, oxygen, and thermal support through the airlock, down to the ground via the crane, and then towed into place in the growing city.
4. Speaking of "modules", I propose that the Starship be configured with multiple modules that serve as living quarters, etc., for the transit that can be disconnected and moved - essentially intact - to their new Mars home, where they can be connected and used rather quickly. This means that the crane & airlock must be able to handle whole modules!

Modules? What are "modules"?

Modules are sort-of intermodal containers, but for Starships and Life on Mars. Outwardly identical, self-contained, and stackable. Think of them as rooms, used for living, or eating, or storage, or whatever. But they are all the same size (probably), and sized so we can stack a lot of them into the payload bay of a Starship.

If a module is a cube 2.75m wide (9 feet), you can fit five of them on one level of the Starship Payload Bay (plus four more diagonal half-cubes, which gives you seven cube-equivalents per layer). There is enough room for 4 layers full width, assuming my guesses about the V3 Starship & Superheavy are accurate. Four layers holds 20 full modules plus another 16 half-modules (great for storage, or even a bathroom). Note that leaves plenty of room above for odds-and-ends, such as a Cybertruck, or a MegaPack, or a large roll of pond liner which can be used to hold the air into a stack of modules in a pyramid or dome structure on the surface, or a large collection of solar panels. Or an excavator, or a bulldozer, or a module-friendly trailer (to be towed behind said Cybertruck) making it easier to move things around. Note than many homes have rooms (bedrooms, kitchens, bathrooms, living rooms, whatever) which are the size of these modules. And just like Intermodal Containers, you can build houses (or condos) which are an assemblage of modules, perhaps with some walls opened up for a door or completely to make a larger room. In a pinch (such as that first couple of years on Mars) a couple could live in one, including their private storage space, as long as they had other public places to eat, drink, entertain, and use the bathroom or shower facilities!

Slightly larger modules (3m / 10 ft wide cubes) also work, but only four fit on a layer, so you can only get 16 in four layers of payload bay.

Slightly smaller ones, work, too, as seven 2.4m / 7ft 11in modules also fit in a layer, yielding 28 per Starship, but by the time you account for ceiling/floor depth, and wall thickness, this begins to feel seriously cramped, and might only work for that first manned mission. Your colonists, after all, must have something to look forward to!

Something very important about standardized modules: they can be pre-configured on Earth for deployment on Mars. Bedrooms can include beds, and closets, and night stands. Lights, power, and standardized connections for air, water, power, and communications as needed. Bathrooms, kitchens, bunkrooms for lots of kids, whatever makes sense. Community showers and bathroom facilities. Community kitchens and dining areas. Rooms containing pumps and blowers to handle the rest of the rooms. Water tanks, waste tanks, agricultural tanks (just like vertical farms or container farms on Earth). I would even suggest that we use some of these on every manned Starship to recycle CO2 and H2O while producing a little bit of fresh food for the tables. This could be done along the outside walls of containers otherwise used to travel between layers and room, serving a dual function of overhead (transportation) and recycling. As a bonus, they can be ported into permanent Mars habitats while already producing enough oxygen for the colonists to breathe and veggies for the colonists to eat, allowing the "farmers" to focus on growing food crops with higher calorie and protein and fat content.

How Many Starships Are Needed?

Elon thinks that the initial mission (unmanned) will have 4 or 5 Starships. He has also said that the first crewed mission will carry 8 astronauts, on 4 Starships. And then he'll multiply the people and Starships by five for each subsequent mission. These numbers are needed to hit his goal of a million people by 2050, which most everyone believes is not realistic. But if he can simply double the number of Starships in each Mars transfer window, he can reach his target only a few years late, sending over 100,000 new colonists in the 2050 window. But that would take a 100,000 Starships, and I don't see SpaceX funding that level of effort, let alone being able to build that many in only two years.

Seeing the first million people on Mars is still viable, it will just take a bit longer, or a lot more support from the rest of the world. If the USA sends a thousand Starships, and China sends a thousand, and Europe sends a thousand, and India sends a thousand, and Japan sends a thousand, and Indonesia sends a thousand, .... (well, you get the picture)!