Pedaling the Stars

Exploration and colonization of the Moon and Mars will require transporting larger loads and traveling greater distances than is practical for humans on foot. Clearly some type of surface vehicle will be needed to effectively explore and colonize. A question to ask is what shape will the vehicles take? What may seem a radical concept is that the vehicles should be human powered. Though this may seem like an improbable solution it actually has a number of benefits over other power sources.

The biggest obstacle to human powered vehicles used beyond Earth is that current space suit designs make this all but unworkable. The problem is that balloon suits used make just walking around heavy exercise. I have argued in an earlier post, Fall Fashion for the Extraterrestrial, that this is an issue that will need to be resolve if we hope to send humans to space for extended periods. The mechanical counterpresure suit suggested should allow mobility similar to a wet suit which will be more than enough to allow the use of human powered vehicles.

One of the biggest advantages of a human powered vehicle is that it will be far lighter than any powered option. The average bicycle weighs about 15 lbs. Though a vehicle designed for transporting the crew on the Moon or Mars will be larger, with the use of high tech materials the basic vehicle will likely only weigh about 2 to 3 times that. That is still less than an average car battery[1] and one tenth that of the Apollo Lunar Rover Vehicle[2]. This provide a huge advantage in launch weight. A vehicle this light can be picked if it somehow gets stuck or to get around an obstacle or carried if it breaks down.

The performance that can be expected from a human powered vehicle is likely more than one might expect. From person experience I know that a person who is in moderately good physical condition can travel and average of 50 miles a day by bicycle carrying 50 lbs. of gear. Rickshaw drivers regularly carry 2 passengers. On the Moon and Mars two factors will allow human powered vehicles to have much higher performance. The most obvious is the difference in gravity, on Mars three times the load and twice that on the Moon. The other is that the biggest limit of the speed of a human power vehicle is air resistance. With little or no atmosphere a human power vehicle should be able to cruise about as fast as is safe to travel over difficult terrain (about 25 mph)[3]. On Mars a human powered vehicle should be able to carry at least 1,000 lbs. of passengers and cargo and possibly a good deal more than that. Someone in good shape should be able propel range at least equal to that of any powered vehicle.

Human power vehicles also excel as all-terrain vehicles. Back in 1897 the US Cavalry experimented with troops mounted on bicycles. A troop of buffalo soldiers traveled 1,900 mile in 40 days from Missoula, Montana to St. Louis[4]. Most terrain you can cover on foot you can ride a bike over. As I mentioned earlier a human powered vehicle can also be carried over extreme obstacles. Consider how literally some people take the term “mountain biking”.

Mountain Biking

Rugged and Robust

Human powered vehicles is a very old technology. Except for detailers the general design of today’s bicycles is almost unchanged from the design developed of 125 years ago. Even though the basic design is old technology the bicycle’s popularity has resulted in a great deal of recent development. What this means for a human powered vehicle for EVA is that almost all the technology needed to make it work can be had off the shelf. Mountain bike designs have focused on a bike that can take a great deal of punishment. A human powered vehicle will have much fewer points of failure than a comparable motorized vehicle.

In the event of an equipment failure just about everything is easily repaired. Part of the reason for this is that a major points of failure are in the drive train. All parts and tools needed to entirely replace a drivetrain can easily be carried along. Repairs in the field would likely take little more than an hour for any but the most catastrophic failures. Even cracks in the frame could likely be temporarily repaired with a splint and heavy duty duct tape.

Active Crews are Healthy Crews

A side benefit of using human powered vehicle is that it will improve crew health. One of the main concerns of extended stay beyond Earth is the loss of bone and muscle mass. It is well know that vigorous physical activity prevent this issue. Especially with respect to Mars missions it would provide a double purpose to the required exercise in transit. If the designers are clever this could also provide extra power for the ships systems.

Shape of the Next Rover

The design of a human powered EVA vehicle will not be a 2 wheeler. The biggest reason is that even with much more advanced space suit design keeping balance will be challenging. Also 2 wheelers are not ideal for carrying cargo. Much more likely will be a recumbent with 3 or 4 wheels. This type of design would be able to be both very stable and provide room for passengers and cargo. The tires are unlikely to be balloon tires. A more likely design would be the Michelin Tweel airless tire design[5]. Part of the cargo may be auxiliary life support. This would likely be a larger version of the personal life support pack that each member of the EVA team has. It would allow the personal life support to be saved for when the crew is moving around on foot.

The Role of Powered Rovers

Though human powered vehicles may be ideal for moving the crew and much of their equipment around there will be many things they can’t do. Though they may not be needed for exploration missions colonization will require loads that a human powered vehicle can’t move and will be needed for jobs like excavation where human power is not likely to be practical. Also remotely operated vehicles will be useful for scouting and other uses. As they will be unmanned they will need a motor.

  1. http://www.carsdirect.com/car-maintenance/car-battery-weight-average-weight-expectations-for-popular-models
  1. http://www.astronautix.com/craft/apololrv.htm
  2. http://www.avdweb.nl/solar-bike/energy-requirements-of-cycling.html
  3. http://www.historynet.com/the-buffalo-soldiers-who-rode-bikes.htm
  4. https://en.wikipedia.org/wiki/Tweel
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