There is a lot of debate about colonising Mars, in fact the conversations have been had for more than 100 years, but realistic plans to at least land humans on Mars are around 50 years old.

In 1976 the debate grew when NASA successfully landed the Viking 1 and 2 landers on the Red Planet, answering many questions and raising thousands of more, and they only poured fuel on the debate about life on the planet with an inconclusive result from one of their experiments, the Labelled Release (LR) experiment indicated that there could be metabolism taking place in the Martian soil they tested, however, later experiements have cast doubt on those results.

The debate about life on Mars is largely over, but the debate of life under the surface of Mars is growing in volume, and whilst robot probes, using current technology, can do a lot, far more that budgets often allow, they are still limited, and the only real way to answer the question is for Humans to land on Mars and stay for extended periods, and realistically, that mean colonisation, so the question must be asked, How feasible is it for huamnity to go to the final frontier and establish an outpost on Mars.


Artist’s rendering of an early Martian outpost showing a Mars ice home and potential complementing greenhouse.
Credits: Image courtesy of Clouds AO

Mars and Earth

How similar are Earth and Mars, well that depends on your personal definition or what you choose as a starting point. In reality, they are not as similar as some would like, me included, but they are similar enough to discuss the idea of colonisation.

This image compares Mars and Earth in their correct relative sizes. Mars (diameter 6790 kilometers) is only slightly more than half the size of Earth (diameter 12750 kilometers). Note the difference in color between the two planets. Almost 70% of Earth’s surface is covered by liquid water. In contrast, Mars now has no liquid water on its surface and is covered with bare rock and dust. The four dark circles in the Mars image are the Tharsis shield volcanos . Africa is at the center of the Earth image. From Viking Orbiter Views of Mars, NASA SP-441, p. 14

Earth                                      Mars

Average Distance from Sun 93 million miles 142 million miles
Average Speed in Orbiting Sun 18.5 miles per second 14.5 miles per second
Diameter 7,926 miles (1.878 x Mars) 4,220 miles (0.532 x Earth)
Tilt of Axis 23.5 degrees 25 degrees
Length of Year 365.25 Days (0.5319 Mars Years) 687 Earth Days (1.880 Earth Years)
Length of Day 23 hours 56 minutes 24 hours 37 minutes
Gravity 2.66 times that of Mars (9.78m/s) 0.375 that of Earth (3.69m/s)
Temperature Average 57 degrees F (13.88 C) Average -81 degrees F (-62.77C)
  • Nitrogen: 78%
  • Molecular Oxygen: 20.98%
  • Argon: 0.934%
  • Carbon Dioxide: 0.0413%
  • Neon, Helium, Methane and Krypton form a combined 0.00264%
  • Water Vapour volume in the lower atmosphere varies from 0-3%
  • Carbon dioxide: 95.32 percent
  • Nitrogen: 2.7 percent
  • Argon: 1.6 percent
  • Oxygen: 0.13 percent
  • Carbon monoxide: 0.08 percent
  • Water vapour, nitrogen oxide, neon, hydrogen-deuterium-oxygen (Heavy water vapour), krypton and xenon form the rest.
  • Methane has been detected, but in trace amounts
Number of Moons 1

The Moon – 2120.48 miles (3476.2km) equitorial diameter


Phobos – 13.8miles (22.2km) and irregular shape.

Deimos – 7.8m (12.6km) and irregular in shape.

As can be seen, there are a number of similarities, but where it really matters, they are, quite literally, worlds apart.

The temperature of Mars is not really an issue for modern humans, these are temperatures encountered in the Arctic and Antarctic all the time and modern materials allow us to tolerate these temperatures for extended periods – this biggest issue is the pressure, at around 100 times less than the surface prsssure of Earth (corresponding to a vertical height of about 35km on Earth), special suits need to be designed that will protect those outside from solar radiation, pressure and temperature extremes, not insurmountable challenges at all, but they need ot be more flexible and tougher than those used by Astronauts, who are not at risk of falling or rubbing against rocks that may tear a suit.

The biggest challenge of Mars is food and water, whilst it is possible to , but we will deal with this later.

Clearly, Mars and Earth have some critical differences, the gravity on Mars is onlly around 40% of Earth, so if you weight 15.75 stone(220Ib or 100kg) on Earth, you will only weigh around 6.3 stone (88Ib or 40kg) on Mars. We know that extended periods of weightlessness has a seriously negative impact on the human body, atrophy of muscle bulk and decalcification of bones are serious matters that can have a long term impact on astro/cosmo nauts who have participated in very long duration mission. We have no experience of how this exposure to 40% of normal gravity will impact human physiology, but it is probable that anyone who spends more than a few Earth years on Mars may have great difficulty returning to Earth, or in some cases, they may not be able to return home at all due to the impact thats Earth’s higher gravity would have on the human body.

Nikola Poljak, from the University of Zagreb in Croatia, and colleagues published a paper in August 2018 that addressed the issue of the maximum gravitational force a human could withstand.  They calculated, from experiment, that a human bone could withstand around 100x Earth’s gravity – standing still. But this does not account for locomotion or the abiulity of the muscles to allow you to breath. They finally concluded that for an average human to walk, run and breath in a gravitational field greater than Earth’s it must not exceed around 3.5 times Earth.

This conclusion puts contraints on those who spend significant periods on another body whose gravity is significantly less than Earth, or, if it happened, any person borne on, in this case, Mars. At 2.5 times Mars Gravity, in theory a human should be able to withstand the difference, and their bones and muscles will strengthen in time, but their diet will be a major impact on how their body responds to the gravity differences. We have no experience of a human body in a different gravity field, we cannot simulate it on Earth and it cannot be replicated in the freefall nature of Earth orbit.

Getting There!!

Getting to Mars can be difficult or simple, cheap but slow (relative term) or expensive but fast depending on when and how you set off on your journey.  The average Journey time to Mars is around 7 months and this is when Earth and Mars are in favourable orbital positions.

Contrary to the ‘point and shoot’ idea, an actual trip to Mars looks very round about as the  above graphic shows for a typical ‘minimum cost’ trajectory. This, by the way, is called a Hoeman Transfer Orbit, and is the main stay of nearly every Mars mission to date.

Hoeman Orbit to Mars at Minimum cost.

It depends on the details of the orbit you take between the Earth and Mars. The typical time during Mars’s closest approach to the Earth every 1.6 years is about 260 days. Again, the details depend on the vehicle velocity and the closeness of the planets, but 240 to 270 days is thetime taken for the majority of unamanned missions set to the Red planet to date. . Some high-speed transfer orbits could make the trip in as little as 130 days.

However, it is possible, with current technology, to get to Mars very fast, actually, in less than 2 months. The New Horizons mission to Pluto and the Kuiper Belt left Earth at 36,000mph (57,960Km/hr) which means it could potentially have reached Mars in around 40 days, depending on where the planets were in their respective orbits.

However, it is not as simple as this, lets assume the planets are at their closest point in their respective orbits, when launching from Earth we need to aim ahead of Mars, regardless of whether Earth is ahead or catching up Mars, because in the time taken to traverse the distance to Mars, the planet did not stop and wait, it continued at 14.5 miles per second, which is 1,252,800 miles per day (2,017,008km). Assuming a journey time of 45 days (to be reasonable) that means we need to aim at a point some 55,366,869 miles (90,765,360km) ahead of Mars in it’s orbit about the Sun, and this has an impact on the speed that your vehicle has to travel at if your travel time is cast in stone.

The biggest problem occurs at the other end of your journey, you cannot enter Mars Orbit at more than around 6500mph (10,460km/hr) or 1.8miles/sec (3km/sec), if you do, you will miss the planet and carry on..not very helpful if you want to get the the surface. It then means you burn a lot of fuel to slow down from your, for arguments sake, 36,000mph (57,960km/hr) or 10 miles/sec (16.1km/sec). Bleeding that amount of momentum will require a huge volume of fuel, and this is the very reason why this type of trajectory has never been used for Mars orbital insertion. Until or unless we develop a powerplant that does not require the lofting of hundreds of tonnes of fuel into space we will be stuck with the 7-9 month journey’s the unamanned missions have, so far, utilised.

We are on the cusp of new types of powerplants, NASA are developing Nuclear powered systems that may or may not prove practicable, although the real issue will be getting them to orbit, the safety implications are massive should anything go wrong. It would make sense that vessels utilising this technology, when perfected, are built in orbit and their fuel is harnessed from the Moon – an obvious source being the abundant helium 3 which is found all over the Lunar surface.

So, when we look at options, we are looking at more sedate speeds to journey to Mars, this means that if we do it in its simplist form the crew/passengers will be expected to experience some 7-9 months of micro-gravity, and we know from astro/comosnauts that extended periods of this have a detrimental impact on the human body.

It thus makes sense that we look at getting to Mars in a far more holistic way than is often spoke of, we need to look at this as something way more involved than Apollo going to the Moon, simply getting in a rocket, even a resusable one, and flying to Mars is not the answer, going to Mars is way more involved, there is no help closeby and thus we need to consider as many eventualities as possible.

Preparations for Humanity’s arrival

Before any Human even sets off for the Red Planet we must look at some very important and often overlooked problems that comes with arriving on Mars for humans to survey.

Mars has no global magnetic field – there is no North, South, East and West in the conventional sense as we understand it on Earth from a navigation perspective, as a result, navigation is going to be problematic, but far from impossible.

At present we have few accurate maps of the Martian terrain, and this needs to be changed. Current mapping missions on Mars do not have the surface detail accuracy for the production of maps for navigation on the surface, thus we need to start looking at ways to address these issues.

Global Navigation…well, we have a solution to this already in Earth orbit, the TDRS/GPS/GLONASS and Galileo systems for GPS Navigation and communication between satellites. Before we send a human to Mars we should send a constellation of Satellites to Mars geostationary orbit to ensure there are 4 above the horizon no matter where you are, that way there iis a high degree of accuracy for 3 dimensional navigation purposes.

Once this constellation is in place any humans who land on the surface can then accurately navigate, record positions and build up accurate maps for those who follow.

Now lets look at landing on the surface of a rather inhospital planet that will do it’s best to kill you and make no mistake, Mars will kill people, there will be deaths in transit, in orbit and on the surface, if people are not prepared for these events then we are destined to fail.

When we get to Mars the last thing we want to do, especially in the early days, is land direct on the suface. Before we send Humans there, we need to build, in Earth orbit, a station, similar to the ISS, but significantly larger, it needs to be able to house up to 50 people for 2.5 years, twice as long as it takes for Earth and Mars to be in ideal transfer orbital positions. The vessel should be rotating at a speed sufficient to provide a significant gravitational effect on the inner “surface”

You may be thinking why, in simple terms;

  1. When humans arrive at Mars they need a safe base to operate from, orbit is the best location for that safe base until humanity can build significant levels of infrastructure, and that may take several decades at least. From here they can take a vessel, land on the surface and start to establish a semi-permanent to permanent presence, but if things go wrong, they have a way to get off the planet even if Earth and Mars are not in ideal positions or the problem is transitory, such as global dust storms.
  2. It is an easy place to launch back to Earth from, it reduces the need for large launch/travel vehicles on the surface and reduces the levels of fuel required to travel between the planets.
  3. It will allow essential research to be carried out by specialists in a gravitational environment without the cost of putting specialist equipment on the surface.
  4. It will allow a more significant study of the asteroids to be undertaken and assesments of possible resource exploitation that would alloow expansion of human presence on Mars and the outer solar system.
  5. It can easily be expanded to become a launch point for human exploration of the outer solar system. Ceres is a very interesting world that can teach us a lot, Mars station would give humanity an accessible and lower launch cost point for human visits to the dwarf planet
  6. It gives humanity a way to study our home planet remotely and look at ways we may be able to extend such studies to exoworlds

Now we need to lok at the logistics of actually having humans on the surface of Mars, this is not the Moon, it is not a few days away, with existing technology it is, as we have seen, at least 7 months away, but it is impractical, in the early days, for the astronauts to take everything they need with them in these early missions, thus the obvious is to launch supply missions to the planet before humans and their orbital habitat even arrive, but how can we do this without supplies spread all over the planet?

Above, we discussed the need for a constellation of navigation satellites in orbit, that should be humanities first task in sending humans to Mars, this should be immediately followed up by ground stations that put down on the surface and their sole mission is to transmit a signal that can be tracked, ground based GPS effectievly, but they should also be able to act as radio broadcast relay stations when humans are on the surface. These stations should be close enough that they can be used to create a landing zone on the surface for the accurate placing of supply missions on the surface, SpaceX has demonstrated that accurate landing of rockets is feasible and repeatable.

Only when we have adequate automated infrastructure on the surface should be consider humans boots on the ground. When we are at that stage, automated missions should be sent with supplies and equipment to land on the surface autonimously, each carrying up to 5T of supplies and equipment. When these are on the surface, well, on their way, we can send crewed missions to the orbital station, because even if something goes wrong with a supply ship, there will be enough provisions on the orbital station that there will be no danger to the crew.

So, in simple terms the colonisation of Mars, because that what it will be, we cannot do an Apollo, we canot simply land, collect some samples and then return to Earth, that makes no sense at all. Establishing a permanent colony or society on Mars is the only solution, or we simply continue to rely on robot missions to explore and not provide the answers we need.

The basic Plan then.

  • Establish navigation satellites in Mars Stationary orbits to ensure that there are 4 above the horizon from any point on the Martian surface, including the polar regions.
  • Establish ground broadcast/relay stations to increase the accuracy of navigation systems.
  • Build, in Earth orbit, an orbital facility capable of housing up to 50 staff for up to 2.5 years. The station should be capable of then being moved from Earth orbit to Mars orbit and rotated to provide a sense of gravity through centrifugal force from the rotation.
  • Send automated supply ships from Earth to Mars, each carrying up to 5T of supplies and equipment, the first to arrive at mars at least 1 calendar month before the arrival of the orbital facility.
  • Once the orbital facility is in orbit around Mars and all systems are working, a construction team would depart the station to land on Mars and begin the process of putting the ground stations together, there would be two ground stations, each capable of holding up to 20 staff and 1.5km apart to ensure that a disaster at one does not impact the second. Each Ground station should be capable of housing the incumbant staff for a period of 2 years without assistance from orbit or Earth.
  • The crew of each ground station should include Engineers, materials scientists, geologists, biologists and support staff.
  • As time continues the ground stations should be expanded to become more colonial in nature –
  • A government structure should be established early in the colonisation process which is fully democratic, using technology to allow all members to be involved in decisions that impact the colony as a whole. All land should be controlled by this government with the purchase and sale of land illegal. All land remains under the control of the Government, to which indivuals and corporations can submit a proposal to for the use of a given section of land, approval requires an 80% vote in favour of the proposal from a randomly selected number of colony residents – randomly chosen by a computer.

There are many technological hurdles to overcome to allow humanity to colonise Mars as many envisage, not least the environmental conditions on the surface, but these are not, as some commentators suggest, insurmountable, yes they are challenging and difficult, but humans have never succeeded because they did the easy, they pushed forward by attacking the challenges we faced and addressing the diffuclkt problems, overcoming them and moving forward incrementally.

This is part one, more will follow.

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