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How I'd Go To Mars

Over on Arcturus, I rashly promised to post something about how I'd do the whole Moon-Mars thing. And so I shall, but with no pretense of technological or future-historical accuracy, though I'll mention some technologies and dates; instead, I'll be building a strawman proposal, with attention to its project-management aspects (in what follows, all definitions are taken from A Guide to the Project Management Body of Knowledge [PMBOK® Guide], 2000 Edition; Project Management Institute).

The first of those being assumptions, whose formal definition is "factors that, for planning purposes, are considered to be true, real, or certain." In particular, I'll assume that stakeholder ("individuals and organizations that are actively involved in the project, or whose interests may be positively or negatively affected as a result of project execution or project completion; they may also exert influence over the project and its results") interests have already been balanced.

They haven't, of course, and the game-theoretic aspects of a program slated to stretch through as many as seven future Administrations, twice that number of Congresses, and nearly thirty Federal budgets, render the prospects for the new space policy rather bleak, I'm afraid. So let's pretend that isn't true. The American public is united in its support (or perhaps cowed into submission, or merely indifferent enough to raise no objection): we're going to Mars! How do we get there?

Another key project-management concept is constraints -- "factors that will limit the project management team’s options." More specifically, "the work [of the project team] typically involves competing demands for scope, time, cost, risk, and quality." The most common framework for evaluating constraints is the triple constraint, colloquially expressed as "good, fast, cheap -- pick two." I've decided I want lots of scope, which means either lots of time or plenty of budget.

I'm vicariously choosing to spend more money and finish up sooner, because I assume that we'll have strong nanotechnology around 2020, after which space exploration requires several orders of magnitude less expense and headcount -- see this section from Engines of Creation for how we might be mass-producing rocket engines superior to the SSME by growing them in vats. Since I'm amusing myself here by envisioning a multi-billion-dollar program with projects all over the world, I'll have none of this cheap, ubiquitous stuff cutting into my bureaucratic empire-building.

Also, because "projects manage to requirements, which emerge from needs, wants, and expectations," I should begin by listing some:

I want the mission to be easily repeatable. That means the creation of processes, vehicles, standards, and infrastructure for follow-on use.

I want to manage the risks associated with long periods of isolation and inaccessibility. That means working our way up to a Mars landing by stages, and it certainly means in situ resource utilization (ISRU) wherever possible.

I want to promote international cooperation, while retaining the lead role for the US and avoiding the execution of critical-path tasks in unstable countries.

I want to engage the public, especially in the US but elsewhere as well.

With all that said, my program would include, but not be limited to, the following projects:

Develop an equatorial launch site (ELS), to be widely but not universally available; first preference goes to the space agencies of free countries with a track record of orderly transfers of power, and to private firms on a case-by-case basis.

Unfortunately, few nation-states on or near the equator are politically stable, prosperous, or entirely friendly to the US; in longitudinal order, they are: São Tomé and Príncipe; Gabon; Congo/Brazzaville; Congo/Kinshasa; Uganda; Kenya; Somalia; Maldives; Indonesia; Nauru; Kiribati; Ecuador; Colombia; Brazil. The US does administer Baker and Jarvis Islands, which are quite near the equator in the mid-Pacific, and are uninhabited. But both are very small -- too small to have, for example, sources of fresh water -- and have been constituted as National Wildlife Refuges. The largest and most economically diversified equatorial nation is, of course, Brazil, but Brazil-US relations are not at their best at the moment.

So something like Sea Launch, but larger and more permanent, might be necessary. Platform technology is well in hand; this source notes that construction of oil-production platforms in 500 meters of water is becoming common, and this news release describes an oil-drilling platform that "has a deckload capacity of around 4,000 tons and is rated to drill to 30,000 ft in just over 3,000 ft of water" -- I note that the Saturn V moon rocket weighed 3,100 tons. I also found a good overview of deepwater development systems, which explains various types of platforms capable of operation in as much as 7,500' (2,300 m) of water. An oceanic launch site might even permit the use of nuclear thermal propulsion in a booster rocket. Speaking of which ...

Develop or scale up high-efficiency propulsion systems, including both nuclear thermal and nuclear electric. A nuclear-thermal booster launched from Earth's surface could theoretically place three-eighths of its mass in low Earth orbit; compare the aforementioned Saturn V, which put 240,000 pounds out of 6.2 million at launch, about one twenty-sixth of its mass, into orbit -- a nuclear Saturn V would have had a 2-million-pound payload!

Nuclear-electric propulsion efficiencies are even greater, but thrust (and therefore acceleration) is low, so their best use is for transporting cargo from Earth orbit to lunar orbit, Mars orbit, and other destinations.

Concomitantly, develop long-term cryogenic storage technology, perhaps with nanomaterials, so that the liquid hydrogen used by both nuclear-thermal and the most efficient chemical rockets can be carried through interplanetary distances.

Evaluate moving the ISS to a low-inclination orbit, possibly even an equatorial one. In any case, this would limit its accessibility from Russian launch sites. Continue to use Russian, Ukrainian, etc, production facilities where possible, and pay to relocate personnel from Baikonur (Tyuratam) Cosmodrome to the ELS (actually to a relatively nearby port city). The ISS then becomes (as slated in the Bush proposal) a medical testbed for gaining understanding of the effects of lengthy spaceflight on the human body, but one with far more economical access from Earth.

Conduct a lunar program largely as a testbed for the Mars program, using the Earth orbit rendezvous (533 kB *.pdf; see page 4) technique to assemble large manned spacecraft and cargo.

Nonetheless, strategically select the lunar landing sites. Some places on the Moon are much more valuable than others. The permanently-shadowed regions at the poles which contain trillions of kilograms of lunar ice are the best known, but there are others as well; turning to T.A. Heppenheimer's Colonies In Space (pp 115-116), we find:

By computing orbits to be followed by the payloads, it has been found that if they are launched from a suitable point on the lunar surface and aimed at a target, they will hit that target even if the launch velocity is slightly off. That is, the gravity of the earth and moon acts to focus the trajectories so they arrive at the target despite slight errors in velocity. The best such launch site is at 33.1° east longitude, near the craters Censorinus and Maskelyne. Then, the target can be chosen as a point in space 40,000 miles behind the moon, known as the L2 point. A catcher or target located there will stay on station, since there the gravity of the earth and moon is cancelled by the centrifugal force due to the orbital motion of the catcher.

This idea was used by James P. Hogan in The Two Faces of Tomorrow. Wikipedia has a good explanation of mass drivers. Coincidentally, Maskelyne crater is near the Apollo 11 landing site (see bottom of page).

Carry out a "dress rehearsal" at the Sun-Earth L2 point, 1.5 million km from Earth. This would allow the crew module's various subsystems to be thoroughly tested without committing the crew to an actual trip to Mars (Wikipedia also has a good entry on Lagrangian points). I would expect that unless the trip to Mars could be made relatively short (like the 1½-month trajectory I computed in this incredibly geeky post), part or all of said crew module would rotate to provide artificial gravity and prevent bone loss, etc. A rotating module with a radius of 50 meters would provide 0.5 g at 3 RPM.

Build a base on Phobos or Deimos first, only then descend to the planet -- and send robots first. This is not an original idea. Besides providing cheap radiation shielding in the form of regolith, the moons are most likely captured asteroids whose bulk composition, in spite of highly desiccated surfaces (134 kB *.pdf), resembles that of carbonaceous chondrites. If so, then Deimos alone could contain over 100 trillion kilograms of water, and therefore over 10 trillion kg of hydrogen, making it an enormous, conveniently located propellant cache.

Deploy Martian comsats and GPS. Mars-synchronous orbital altitude is 17,400 km (20,800 km from center of planet), about 11,400 km above Phobos and 2,700 km below Deimos. Three satellites spaced 120° apart would provide continuous communication with Earth and everywhere on Mars below ~78° N/S latitude. Assuming both the transmitting antennae on the satellites and the receiving antennae on Earth are accurately pointed 10-meter-diameter paraboloids, the transmitter power is 1 kW, and the system is using X-band wavelengths (8 GHz) with a bandwidth of 10 MHz, then at a typical Mars-Earth distance of 160 million kilometers, the channel capacity would be over 40 megabits per second (I built a spreadsheet a few years ago, based on a chapter in this book, to do such messy calculations). The actual maximum data rate from (for example) Mars Odyssey is 110 kbits/sec, because its transmitter power is only a few watts and its high-gain antenna is only about a meter in diameter.

Land someplace cool. Several places, actually, starting with a high-latitude site for access to subsurface ice for refueling. Charitum Montes would do. Then on to the spectacular Valles Marineris, and be sure to visit Olympus Mons. If the energy requirements of rocketing from one site to another are prohibitive, drive instead. Deploy lots of drone aircraft while you're at it, and send back plenty of video!

And now for my larger point. Besides the imminence of nanotech making a high-level-of-effort program obsolete within two decades, the above scenario is clearly strewn with arbitrary elements. Even within the constraints of bulk technology, there are a vast number of possible approaches to exploring Mars. But the political process will necessarily close most of them off, and there is simply no reason to believe that even if a manned Mars program somehow survives (at least) four or five Administrations, eight or ten Congresses, and fifteen or twenty Federal budgets, it will have selected and executed the most scientifically productive of the alternatives. Any directly publicly-financed effort will make plenty of idiosyncratic choices, to say nothing of political rewards to powerful legislators. So as silly as my ideas may be, they almost certainly are no worse than what the NASA-Congress-Administration system will (attempt to) produce.

I don't always agree with Bob Zubrin, but his Mars Prize idea, which simply dangles a $35 billion carrot to be munched by whoever gets there first, is far more attuned to the decentralized nature of a free society than the way we (try to) do things now.