by Chris McMahon
I’m still musing over orbital schemes to allow us to get around the solar system.
Thanks to Martin Shoemaker for putting me onto the Mars Cycler scheme following last week’s blog. Here is the link to the Aldrin Cycler on Buzz Aldrin’s page.
This is basically a scheme to have a spacecraft travel from Earth to Mars in a regular series of orbits that turn the Cycler spacecraft into a solar suburban bus. Hop on at Earth to hitch a ride to Mars or hop on at the other end to return to Earth.
The orbital mechanics is complex, and solving it is regarded as much an art as a science. Various solutions are possible to the same problem, and each aims to offer the best mix of course corrections and gravity swings to yield frequent, regular arrivals at both Mars and Earth, while using the least fuel.
There are various schemes. Aldrin’s cycler takes 150 days to reach mars and around 20 months to return or 150 days from Mars to Earth and 20 months back to Mars. These two symmetrical schemes are dubbed the ‘up’ and ‘down’ escalator orbits. This implies that one Cycler could transfer people up and back in 26 months or so. The idea is to have more than one Cycler spacecraft.
Here are the main transfer points of the Aldrin Cycler Scheme:
Earth to Earth orbit.
Earth orbit to the L-1 spaceport. This Lagrange point (where the gravity of the Earth and Moon cancel out) lies in a direct line between the earth and moon. Positioning the spaceport here enables it to maintain its position with minimal course corrections.
Transfer from the spaceport to Cycler spacecraft. Remember the Cycler doesn’t stop – you have to use a transfer craft to catch up with it and jump on board.
Cycler to Mars spaceport, which will be similarly positioned in a neutral gravity zone near Mars.
Mars spaceport to Mars orbit.
Mars orbit to surface.
The biggest issue is the long periods in space. Life support is critical, and protection from radiation. You would definitely want to take your video games for that trip. Loss of communication with Earth is also a potential issue. If only we had subspace communicators, eh?
The idea was to rotate the Cycler spacecraft to provide artificial gravity, starting at a full g from Earth. Aldrin’s original idea was to reduce this artificial gravity from 1g to 0.34g on the trip out – which matches Mars gravity – to assist in acclimatisation. I get uneasy about reduced gravity. We probably need some long term studies to determine the effect of living at 0.34g before we commit to this or long-term Martian habitation.
Anyone got any good links for the effects of reduced gravity? Or the effect on the development of mammalian pregnancies in low-g? In my SF short Memories of Mars (Anywhere but Earth), I addressed this by having pregnant women travelling to a Martian satellite spun to 1g for the term of their pregnancies, and children schooled in orbit, also at 1g.
Mad Genius Club 
13 responses to “Mars Cycler”
You might take a look at these reports about hypergravity http://ntrs.nasa.gov/search.jsp?R=20030001110
http://ntrs.nasa.gov/search.jsp?R=20010048658
Cheers. Thanks Mike.
Very cool! 🙂
Ages ago I drew up a plan for a lunar base. It included a large funnel shape, composed of rings rotating at higher and higher velocities. You step in at the top and walk down to where you’ve got 1G, and spend however much time your physician recommends there. Kids would have several play times a day there, no doubt getting to trouble playing tag across the various bands.
Nice idea. The long term effects of reduced gravity seems to be a very big neglected elephant-in-the-room of space travel and colonisation. The blanket assumption of many Golden Agers that reduced gravity would be either benign or even good for health has had way too much influence on latter SF.
There’s a “popular science” book about research into the biology and psychology of long-term space travel and residence. The author is Mary Roach and the book is entitled “Packing for Mars.” She has OK end notes and solid data, but the tone of the book is quite breezily “gee whiz,” too much so for my taste.
Cheers – I’ll check it out. I need a bigger bookshelf damnit!
There’s no constraint on the size of the Mars Cycler. So, lasso a couple fair-sized asteroids, put them in the requisite orbits, then hollow them out and spin them up to use as space habitats. Make the Cycler itself a destination. You’d have 3 societies. Earthers, Martians, and Cyclers. The last would trade between the planetary societies.
I like the idea. Big investment to get the asteroids in the first place, but they would make great radiation sheilds:) The bigger the Cycler community was, the less of a critical issue with life support failure – i.e. more buffer zone. If the Cycler community had their own industries, it would be a case of basically short-term employment – or recreation while you travel. Great concept.
Chris, why “transfer” from station-to-Cycler? As the other Steve points out, the Cycler’s only defining characteristic is its course. Board your Pullman car at the starbase, and the base catapults your luxury accomodations out to rendevous with the Cycler. Match velocity and become part of the spacecraft for the next few months, while the pods it just dropped are decelerating to dock at the base …
Make part of the station a pinwheel, spinning such that the tips of the spokes approximate the velocity of the Cycler on the Moon-side of the station. Then the cars could move between the two, in either direction, with a minimum of wasted fuel/reaction mass. Leave your returning car, climb up the spoke to the zero-gee hub, and transfer laterally to the non-spinning portion of the hub to find your Earth shuttle — after visiting the gift shop, of course. 🙂
The problem with htis is geo-politics, not physics. YOU can take the job of convincing the hordes of tinfoil-hatted Luddites that it’s safe to have a craft moving at interplanetary velocities pass that closely to the planet. I’m not going to try.
Nice idea. If only my spacecar could do better that low Earth orbit:) Time to upgrade.
On any spin for gravity space habitat concept, I tend to be a bit interested in the mechanics of the rotation. I put together, and then lost a spreadsheet for sanity checking the Island Three concept in particular and wheels/cylinders in general.
(I used the 27th ed of the Machinery’s Handbook, mainly the section on flywheel bursting speeds. This gives conservative results, but those say something about what sort of material science is needed, and how damage tolerant the thing might be. Plus, if one puts a space population in exploding cigars, that is a story right there.)
Good thinking. There is a lot of science and engineering missing from these concepts.