The Ultimate Secret to Settling Mars

Cover image by Ville Ericsson

Here's the big misconception...

​Mars Exploration = Mars Settlement

The truth is -- exploring Mars has very little to do with settling Mars, at least if you define 'settlement' as the ability to get hundreds and thousands of people to Mars.

Related: Explore or Settle? Our Approach to Mars

But here's the good news.

There are certain things that can be done to support both settlement and exploration -- and one thing in particular that could absolutely transform our ability to put hundreds of people on the surface.

​What is it?

​Orbital Refueling - the Secret to Settling Mars

​A few years back, a paper was presented by John Strickland at the  International Space Development Conference called Access to Mars (an initial version was presented a few months earlier at the 13th International Mars Society Conference). The paper focused on how best to get to Mars but had a strong focus on one element...

Get instant access to the complete paper.

Access to Mars

Earth to Mars Transit - Logistics Alternatives

by John K. Strickland​, Jr.

Gas stations.

​Specifically -- orbital gas stations.  Propellant depots, as Strickland called them.

Gas stations orbiting Earth. And gas stations orbiting Mars.​

The paper was a high level overview of why propellant stations would be a good thing for exploration, but in reality, they are more than that...

They are the secret to settling Mars by the hundreds and thousands.

propellant depots - the secret to settling Mars

Screenshot: Access to Mars by John Strickland

​Why is this such a big deal for settling Mars? 

​Let's take a look ...

What would it be used for?

  1. Vehicles arriving from Earth can be launched with less fuel, which means lower mass, use an aerocapture maneuver to reach a propellant depot in Mars orbit, refuel and then descend to the surface. ​Instead of lowering the mass from Earth, however, we could also keep it the same and just deliver more - more people, more equipment, more supplies.
  2. An orbital propellant depot can double as a processing station for new immigrants - a place where they can gather before boarding re-usable landers. The reverse is also true. The station would be disembarkation point for those wishing to go back to Earth.
  3. Orbital transfer vehicles from a Cycler could refuel and return to the Cycler.  A return to Earth becomes much easier and much more manageable.
  4. An orbital station around Mars would aid exploration. Re-usable exploration vehicles could reach orbit, refuel, and land anywhere else on the planet.  The whole planet would be within reach with just one station.  New missions would not have to be launched all the way Earth to study new sites.

Where would it be located?

​When planning the location of a refueling station around Mars, there are a few things to consider:

are orbital propellant depots the secret to settling Mars?

Cryogenic propellant depot with single sunshade. Image credit: United Launch Alliance, B. Kutter, 2008.

  • The base should be high enough to avoid frequent orbit re-boosts which use up fuel (about 400 km high or more – Low Mars Orbit.  
  • If the orbit is elliptical, it will reduce the number of opportunities for landings and takeoffs compared to a circular orbit.  
  • A High Mars Orbit (HMO) would require a lot more fuel to reach from the surface and for landings than a LMO.  
  • A near-equatorial orbit would get a delta-v boost due to Mars' speed of rotation - just like it does on Earth.
  • A high inclination or polar orbit would increase the propellant needed for landings and takeoffs considerably.  It would also reduce the number of opportunities for landings and takeoffs compared to a near-equatorial orbit.​
  • A Highly Elliptical Mars Orbit (HEMO) would make access to and from Earth-Mars Cyclers much easier, but fuel requirements for Mars landings and takeoffs would be much, much higher compared to LMO.

​So it appears that a near equatorial, Low-Mars Orbit may be the best choice. But what about Phobos? A recent article from the Planetary Society described why Phobos might even be a better choice.  

Phobos orbits Mars at a fairly low altitude (6,000 KM) and passes every 8 hours.  That's pretty fast -- and much higher than a Low-Mars Orbit, which makes it much more difficult to reach from the surface of the planet. The potential of using the moon's own resources to produce fuel, however, may make it an irresistible choice.

Obviously, more study needs to be done.

​Why this is Critical for a Mars Settlement?

​A Mars orbital station is one of the key, 'must-have' technologies we laid out in our recent article entitled:

10 'Must-Have' Technologies for Settling Mars​

The basic reasons this is so critical are these:

Fuel depot concept

Fuel depot Concept. Credit: NASA

  • It gives the settlement a purpose beyond just living and exploration - and a potential source of income. Bring fuel to the depot and charge others for its use.
  • The settlement maintains itself as a 'space-faring' settlement and is not just tied to surface operations.
  • It extends the reach of colonists and explorers to the entire surface of Mars, not just one or two small outposts or bases.
  • The LMO can be replicated from designs for a Low-Earth Orbit depot. This means it can be tested and used before it is ever sent to Mars - a critical safety feature when you are so far from home.  Replication would also mean lower cost - at least if a few of them were built. Finally, LEO stations would provide another potential source of income.


​The secret to settling Mars does not lie in designing big, huge ships, or even smaller ships that are 'one and done' - single shots to the surface of Mars for a 'flags and footprints' political statement. 

That may be OK for exploration missions that have no intention of staying.  But not for settlement​.

No, the secret to settling Mars, the secret to putting hundreds and thousands of people on the surface,  is really quite clear: ​simplify access to the planet -- and replicate.

Sounds easy, but - obviously - doing it is much harder. ​Putting refueling stations in a Low-Mars Orbit, though, may just be the key to opening Mars for the many.

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What do you think? Is an LMO propellant depot the secret to settling Mars? Share your thoughts in the comments below.

1 comment

  1. Gary D Brown 21 May, 2017 at 23:27 Reply

    How does the xenon ion engine fit into the fuels mentioned. Solar electric engine is what it’s called I believe. New sodium nuclear with a 33 year lifespan. Nuclear subs never need refueling. Virginia class subs kind of look like a habitat for Mars in shape currently are working. They convert CO2 for oxygen and sea water to split H2O into Hydrogen and Oxygen.

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