In terms of the scale of the effort for colonizing North America, I think it is useful to compare the size of the naval fleets of the time and other historical benchmarks. We know how large the military is today and the share of the total economy that it has. It will be more useful to approximate how large the interplanetary space travel industry will need to be before an interstellar colonization expedition would be a reasonably sustainable activity.
Technology will be key in lowering the costs and energy requirements (even for communication). However, we will need to build up the economic scale and interplanetary space capabilities to achieve sustainable results and progress.
Military Comparisons to Colonization
The Spanish Armada of 1588 at wikipedia
The Spanish fleet was composed of 151 ships, 8,000 sailors and 18,000 soldiers, and bore 1,500 brass guns and 1,000 iron guns. The full body of the fleet took two days to leave port. It contained 28 purpose-built warships: 20 galleons, 4 galleys and 4 (Neapolitan) galleasses. The remainder of the heavy vessels consisted mostly of armed carracks and hulks; there were also 34 light ships present.
In the Spanish Netherlands 30,000 soldiers awaited the arrival of the armada, the plan being to use the cover of the warships to convey the army on barges to a place near London. All told, 55,000 men were to have been mustered, a huge army for that time
English fleet however did outnumber the Spanish, with 200 to 130 ships, however the Spanish outgunned the English fleet: its available firepower was 50% more than that of the English. The English fleet consisted of the 34 ships of the royal fleet (21 of which were galleons of 200 to 400 tons), and 163 other ships, 30 of which were 200 to 400 tons and carried up to 42 guns each; 12 of these were privateers owned by Lord Howard of Effingham, Sir John Hawkins and Sir Francis Drake.
Largest cities in Spain in 1600: Sevilla (40,000), Toledo (44,000), Madrid (40,000), Barcelona (40,000), Valencia (35,000), Valladolid (32,000), Córdoba (25,000). Population of Spain in 1600: 9 million.
One of the most successful conquistadors was Hernán Cortés, who with a relatively small Spanish force but also crucially the support of around two hundred thousand Amerindian allies, overran the mighty Aztec empire in the campaigns of 1519–21 to bring what would later become Mexico into the Spanish empire as the basis for the colony of New Spain. Of equal importance was the conquest of the Inca empire by Francisco Pizarro, which would become the Viceroyalty of Peru. After the conquest of Mexico, rumours of golden cities (Quivira and Cíbola in North America, El Dorado in South America) caused several more expeditions to be sent out, but many of those returned without having found their goal, or having found it, finding it much less valuable than was hoped. Indeed, the American colonies only began to yield a substantial part of the crown’s revenues with the establishment of mines such as that of Potosí (1546). By the late 16th century American silver accounted for one-fifth of Spain’s total budget. In the 16th century “perhaps 240,000 Europeans” entered American ports.
More people and money over the course of century than were on both sides of a very large naval engagement. There were also expeditions and fleets of colonizing ships (1-11 ships were common).
Region / Country GDP (PPP)
mill. of International dollars GDP Share percentage (%)
World 329,417 100
Ming China 96,000 29.2
Mughal India 74,250 22.6
Far East (excluding China, India,
Japan, Russia) 24,088 7.3
Africa 22,000 6.7
Spanish Empire 20,789 6.3
France 15,559 4.7
Italian States 14,410 4.4
Ottoman Empire 12,637 3.8
Germany 12,432 3.8
Russia and Central Asia 11,447 3.5
Japan 9,620 2.9
Eastern Europe (excluding Russia) 8,743 2.7
Spain 7,416 2.1
British Isles 6,007 1.8
The voyages of Christopher Columbus are invoked by Americans more than any other historical analog to capture the ethos of the manned space program. A better analogy would be Leif Ericksson. He and his fellow Norsemen reached North America five centuries before Columbus by travelling in the most remarkable sailing vessels of their time. Not until Columbus, however, did Europeans have at their disposal a robust maritime technology that would allow them to not only reach the Western hemisphere but also to sail back and forth to Europe reliably. Over the last forty-five years, the United States has developed space launch vehicles that can carry astronauts to near-Earth orbit and even to the moon. It has failed, however, to develop the space ship that can do for the United States what the caravel did for Columbus. The current program to build a new suite of launch vehicles simply recycles old technology. It builds longships, not caravels.
Colonial Population Estimates
North American Latin American Europe
Year Population Population Population
1750 1,170,800 16 million 163 million
1800 7 million 24 million 203 million
1850 26 million 38 million 267 million
Northern America comprises the northern countries and territories of North America: Canada, the United States, Greenland, Bermuda, and St. Pierre and Miquelon. Latin America comprises Middle America (Mexico, the nations of Central America, and the Caribbean) and South America.
The figures for North and Central America only refer to post-European contact settlers, and not native populations from before European settlement.
Future Space Settlements
If (when) there is human settlement of space and
If there were parallels to the scale of the settlement of the Americas.
then there would be thousands of spaceships capable of carrying hundreds of people at a time for interplanetary and later interstellar travel. The interplanetary capability (out to the Oort comet cloud) would be something like the ships traveling and trading around the mediterranean.
Stages of ease of movement around space
Ease of getting to orbits and to the moon and near earth asteroids
Ease of getting Mars (1. AU) the Asteroid belt (between 2.3 and 3.3 AU)
Ease of getting out to Saturn (9.5 AU)
Ease of getting out to the Kuiper belt (30 and 50 AU with over 100,000 Kuiper belt objects with a diameter greater than 50 km and a total mass of 1-10% of earth)
Ease of getting out to the Oort comet cloud and the gravitational lensing points
The hypothetical Oort cloud is a spherical cloud of up to a trillion icy objects that is believed to be the source for all long-period comets and to surround the Solar System at roughly 50,000 AU (around 1 light-year (LY)), and possibly to as far as 100,000 AU (1.87 LY). It is believed to be composed of comets which were ejected from the inner Solar System by gravitational interactions with the outer planets.
Ease of getting out to other solar systems (brown drawfs and stars)