Getting to Mars

Getting to Mars is, quite literally, going to be a case of turning science fiction into science fact.

I thought you’d enjoy looking at one of the suggestions under consideration by NASA for a craft capable of taken humanity to Mars and beyond.


The Nautilus is a true space ship in that, like the International Space Station, it will be built on Earth but assembled into its final form in space. And, like the space station, it can never come back to Earth in one piece. If it ever enters the depths of our atmosphere it will do so in a fiery ball.

Also, like the space station, the Nautilus relies heavily on solar power.

The first things most people notice when looking at the Nautilus is the inflatable side modules, effectively quadrupling the internal usable space within the craft.

Bigelow Aerospace has already demonstrated the effectiveness of inflatable habitats in space, and with the outer skin able to seal itself in the event of a micro-asteroid breach, NASA are looking to trial these on the International Space Station.

A scene from 2001: A SPACE ODYSSEY, 1968.The donut-shaped ring in the midsection is an ingenious idea that’s been around since the 50s in science fiction but one that has never been put into practice in orbit. It’s a spinning, revolving torus that gives the illusion of gravity.

Have you ever seen one of those small, hand-pushed roundabouts in a child’s playground? My kids love them. My kids cheer as I spin them faster and faster, and the conservation of angular momentum gives them the illusion of an outward force, seemingly pushing them to the edge of the roundabout.

In the same way, the spinning torus on the Nautilus will give the sensation of gravity to astronauts. The weightlessness experienced by astronauts in constant free-fall is a serious problem for any mission to Mars.

In space, bone density drops at an alarming rate, giving a forty year old the bone density of a 70-80 year old inside of a year. Muscles atrophy and waste away, which has serious implications for the heart. Bodily fluids redistribute causing havoc for the sinuses, and sleep patterns are disrupted. Space is a tough environment. At least 50% of astronauts end up with space sickness for the first couple of days (similar to sea sickness), so simulating gravity could bring some very real benefits to prolonged space exploration.

The proposal before NASA is to spend just over two years developing a centrifuge torus add-on for the International Space Station to test this concept in a low-earth orbit.

Partial gravity of the torus

Revolutions per minute 30 foot diameter 40 foot diameter
4 0.08 0.11
6 0.18 0.25
8 0.33 0.44
10 0.51 0.69

It may not sound like much, but even at four revolutions per minute, this minuscule simulated gravity would be enough to keen a sleeping astronaut comfortably in one spot. At eight revolutions, the torus would have a similar gravitational “feel” to the Lunar surface, while ten revolutions gets up to half what we experience on Earth.

Here’s an artist’s impression of the ISS centrifuge demo. Note that the torus is also partially constructed out of inflatable materials.

Centrifuge demo on ISS

If this project goes ahead, it will give NASA the opportunity to evaluate the viability of a similar torus on a manned/womanned  mission to Mars.

In particular, NASA is keen to understand the impact of changing exposure between weightlessness and simulated, partial gravity, looking to understand the physical as well as psychological impact. There are implications for the vascular system, ocular (sight), skeletal and muscular as well as excretory systems (no astronaut would complain about partial gravity when going #1 or #2). One possible downside, though, is scientists expect the transition in and out of the rotating torus may lead to vomiting.

But perhaps the most interesting aspect of the Nautilus design is something the observant reader may have already picked up on in the first image: there’s no engine.

What good is a space ship without an engine?

Actually, this is ingenious. Engines are big. Fuel is massive, that is to say, it takes a lot of fuel to carry fuel. The Nautilus uses a modular engine design, meaning the engine is just another module like those inflatable pods on the side of the craft. The initial configuration of inflatable modules has three pods, but the fuselage could easily be extended to include six, nine, twelve, etc, without adding that much mass proportionally, and the fuel cylinders and engines work much the same way.

The engine is modular, attaching to a plate at the rear of the space craft.

Rather than building the engine into the space craft, NASA can simply bolt on whichever engine is suitable for a particular mission. And in some cases, that may be no engine at all, as in a second space station or small engine when waiting at a gravitationally neutral Lagrange point, like the one between Earth and the Moon.

Lunar station

On some missions, an ion engine might be appropriate, on others a traditional rocket, but, more to the point, this modular design means a mission to Mars can send its return engine and fuel on ahead of itself at a slower pace, saving fuel on the outbound journey.

Using a design like the Nautilus to go to Mars would give our intrepid martian explorers their own space station in orbit while they explore the surface.

The Nautilus is a step in the right direction for developing a spaceship capable of travelling to Mars and beyond. For those that are interested, I’ve attached a presentation that goes into the design in more detail.

Here’s an example of a configuration that could be used on a mission to Mars.

Mission to Mars

6 thoughts on “Getting to Mars

  1. Great post, Peter! Very informational.
    The modular design is truly revolutionary, and I think it’s one of the biggest steps in our space-flight endeavors. The materials are also mind-boggling and without them, it’s hard to imagine any of our dreams to conquer space would ever become a reality.

    • Yeah… I think the modular design of the inflatable pods and engines is a good practical solution to space travel, especially as a craft like this would stay in orbit and be reused over and over again (asteroid missions, missions to Venus, etc), so all they need to do between missions is a bit of housekeeping and send up a new engine.

  2. Well, I guess we’ll have to simulate gravity that way. Looks so odd, like Earth’s destroyers in Babylon 5. The self seal of the material, is it like the one’s used in combat heli’s? I know they are bound to test those in the ISS but didn’t knew it could self seal. Also, Mars Society is thinking of those modules as ealier habitats for exploration or colonization (I’m guessing for a canyon so they can sealed it and build more inside).

    Instead of having a donut, why not have the modules rotate to simulate gravity and have the docking stationary. Wouldn’t that increase the space for explorers to rest and work? Do you think we might get a Helium 3 engine by then? I heard they could get a major punch from that, plus energy generation for the ship. But I digress a lot as you noticed.

    • Hah… all good concepts. From what I understand the rotating torus would be used primarily during sleep. NASA could rotate the inflatable habitats but they’d have to keep the weight carefully distributed between pods, which might be impractical. If this concept works on the ISS and the rotating torus can be used for sleep (which spans a good stretch of time during any 24hr day) and the artificial gravity counteracts the effects of weightlessness on the body over prolonged periods, then it would be an important part of getting the astronauts to Mars in a fit and healthy state.

  3. Pingback: Robert JR Graham » Will an Ion-Drive Spaceship Take Humans to Mars?

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