A Basic Rover for the Base - to be built on Mars

louis · 2017-05-08 14:14:43

I posted this under a thread which was really intended for larger more robust rovers, so thought I would start a new thread.

This is concerning a 98% Mars ISRU Rover design, specifically a design for a small one or two passenger Rover, to be used exclusively around the base on stone-free ground, for transport from one hab to another.

Having watched some You Tube vids of kids bulding Go Karts, I thought this would be well within the capacity of an early settlement.

I was thinking about it having the following features:

- Solid steel frame or steel tube frame. (Would steel tube allow for air heating?).

- Steel spring suspension.

- Chemical battery

- Electric motor

- Drive shaft

- Aluminium wheels or caterpillar tracks.

- Pressurised cabin constructed from honeycomb aluminium and with a basalt rockwool insulation layer (contained in a steel frame). Will have a single small air lock door.

- Cabin air supply system operating off gas cylinders. Good for 60 mins. Most journey times will be less than 5 mins (passengers will also carry emergency air supply on their person).

- Cabin would have its own battery operated heating system.

- No steering wheel column . Front wheel drive to be operated by radio control on a games console style device affixed to the inside of the cabin.

- Cabin to include either a narrow, thick pressure-proof windscreen with dust blowers to keep the windscreen clear, or to be driven by a camera/video screen system with no windows.

- Headlights operating off their own batteries. Brake lights not required. Only one vehicle will operate on the base for safety reasons.

- Max speed - 5MPH. No gears.

Some questions:

In what temperature range could such a vehicle operate? I'd like it to be able to operate in winter (during the lightest hours of the sol - not at night) as well as in summer.

Would caterpillar tracks work all right on Mars on fairly flat ground?

SpaceNut · 2017-05-08 15:41:05

I sure did see it and this twist to the topic is along the same lines as the light weight rover that is simular to apollo that we would want as a first set of wheels...

Your list was a good way to make it possible to build a simple means to move people or something larger as we do make use of insitu materials..

Which brings us back to how do we leverage the insitu materials into these items? We must bring something to get started with for doing so....right what is that name ,,, oh I know but that would highjack the topic again....

louis · 2017-05-08 16:17:17

I think I know what you are talking about...but I guess a lot of small scale machines would be involved in the production of this vehicle.

Let's call it Base Rover 1.

SpaceNut wrote:

I sure did see it and this twist to the topic is along the same lines as the light weight rover that is simular to apollo that we would want as a first set of wheels...
Your list was a good way to make it possible to build a simple means to move people or something larger as we do make use of insitu materials..
Which brings us back to how do we leverage the insitu materials into these items? We must bring something to get started with for doing so....right what is that name ,,, oh I know but that would highjack the topic again....

kbd512 · 2017-05-08 16:21:41

Use a RTG and super-capacitors instead of batteries. The electric motors will be directly connected to the drive sprockets. It'll weigh more but it'll last a lot longer and won't have any power-related range limitations. The interior will be lined with PE foam or BNNT wool fabric for radiation shielding and the RTG can supply thermal control using a radiator and water.

Keep the lights. Lights weigh very little, LED's use very little power, and lights are important safety features for people outside the vehicle. A spot light and thermal imager are needed to look for injured or unaware people at night. The driver should have his own night vision equipment and the assistant should have equipment mounted to a turret to get 360's around the vehicle.

The RTG provides enough power to run life support equipment (limited to thermal control, pressurization, and CO2 removal using CAMRAS) and to recharge the super-capacitors. Little support infrastructure is required. The water tank will provide both drinking water and thermal control. A LOX bottle refilled at the base can provide O2.

The Japanese Type 60 APC is what I had in mind, substituting Titanium alloy for steel.

Two separate compartments, one for the driver and assistant (person who watches the cameras to ensure the vehicle doesn't run anyone over and operates the radios) and one for the passengers. Seats 6 people in suits. A hatch could connect directly to the passenger compartment so no EVA is required to enter/exit the vehicle at the base. It's very low to the ground, so unless the ground gives way, rolling it would be nearly impossible.

It's a 5,000kg vehicle (1,900kg on Mars), but it's built to last.

Buy once, cry once.

louis · 2017-05-08 16:50:42

Ah well suond like you are thinking of something bigger than I was - I was thinking more of a "tuk tuk" type vehicle, albeit pressurised. I wanted to keep the Base Rover small so it could easily pass through air lock doors, rather than people having to get out of vehicles in space suit breathing from carried cylinders, or - alternatively - having to design special systems for vehicles to lock on to air locked chambers. However, if there was some sort of hatch system that didn't add too much cost and complexity, that might work. But I don't think we need a huge vehicle for moving around the base, in fact would be a disadvantage as it would represent a safety risk.

We probably need a transport hab on the outskirts of the base where the larger Rovers can be stored while the smaller ones ply between the pressurised habs.

kbd512 wrote:

Use a RTG and super-capacitors instead of batteries. The electric motors will be directly connected to the drive sprockets. It'll weigh more but it'll last a lot longer and won't have any power-related range limitations. The interior will be lined with PE foam or BNNT wool fabric for radiation shielding and the RTG can supply thermal control using a radiator and water.
Keep the lights. Lights weigh very little, LED's use very little power, and lights are important safety features for people outside the vehicle. A spot light and thermal imager are needed to look for injured or unaware people at night. The driver should have his own night vision equipment and the assistant should have equipment mounted to a turret to get 360's around the vehicle.
The RTG provides enough power to run life support equipment (limited to thermal control, pressurization, and CO2 removal using CAMRAS) and to recharge the super-capacitors. Little support infrastructure is required. The water tank will provide both drinking water and thermal control. A LOX bottle refilled at the base can provide O2.
The Japanese Type 60 APC is what I had in mind, substituting Titanium alloy for steel.
Two separate compartments, one for the driver and assistant (person who watches the cameras to ensure the vehicle doesn't run anyone over and operates the radios) and one for the passengers. Seats 6 people in suits. A hatch could connect directly to the passenger compartment so no EVA is required to enter/exit the vehicle at the base. It's very low to the ground, so unless the ground gives way, rolling it would be nearly impossible.
It's a 5,000kg vehicle (1,900kg on Mars), but it's built to last.
Buy once, cry once.

kbd512 · 2017-05-08 18:50:38

louis wrote:

Ah well suond like you are thinking of something bigger than I was - I was thinking more of a "tuk tuk" type vehicle, albeit pressurised. I wanted to keep the Base Rover small so it could easily pass through air lock doors, rather than people having to get out of vehicles in space suit breathing from carried cylinders, or - alternatively - having to design special systems for vehicles to lock on to air locked chambers. However, if there was some sort of hatch system that didn't add too much cost and complexity, that might work. But I don't think we need a huge vehicle for moving around the base, in fact would be a disadvantage as it would represent a safety risk.
We probably need a transport hab on the outskirts of the base where the larger Rovers can be stored while the smaller ones ply between the pressurised habs.

If I understand this correctly, the rover has to fit through an airlock designed for humans because you don't want a special air lock for the rover to use and you don't want people to have to EVA to get into the vehicle. I can think of a way to give you two but not three of the design criteria you wanted, so which two are most important?

For the rover to seal to the airlock, it must be bigger than the airlock so it's not going through an airlock designed for humans. I can make it a lot lighter using wheels and inflatable fabrics, but something has to give.

SpaceNut · 2017-05-08 18:58:36

nice transformation of the vehicle into something a bit more capable but still what do we need to provide to make it happen... not sure how soon we would be able to make our own RTG units....

edit for the air lock?

To be at ground level means a huge change in the structure to which would have one...but if we add on to the hab with a made to order ground level air lock as kbd512 indicated one could back it up to the structure docking ring and dock the vehicle.

kbd512 · 2017-05-09 00:11:09

SpaceNut,

I think that the practical considerations for living on Mars have given way to this notion that we can make things that are light and therefore cheap, but somehow have the functionality of things that are not light or cheap to make or deliver.

In the OP, Louis described a vehicle that's never going through an airlock designed for humans. If that's the case, and it obviously is if it has a pressurized aluminum honeycomb cabin, then he doesn't really care about that sort of functionality or hasn't thought about what the design specifications imply. The steel tubing is really perplexing. What would a pressurized rover going 5mph max over flat and level ground ever need steel tubing for?

I guess he was thinking about something like a STS rescue ball on wheels. We could use permanent magnets affixed to small electric motors to spin rollers attached to the exterior of the ball. The ball can run up an aluminum ramp using the diamagnetic properties of aluminum to mate to the airlock if the airlock also has magnets attached to the exterior. The ball must be constructed of a flexible fabric. Pressurization would add the required rigidity. The interior fabric ball would contain a slip ring so the human doesn't tumble inside the ball during transit.

Apart from not requiring a space suit, why would we make a vehicle that only moves as fast as a human can walk when a human in a MCP suit could get to where he or she was going even faster by jogging and be in far less peril in a functional space suit?

If the pressurized cabin loses power or pressure during transit and it's the only vehicle on the base, then it really doesn't matter if you have an emergency oxygen supply or not because nobody can get to you for several hours. You need to be in a space suit to survive either of those events, which negates the entire utility of this concept.

louis · 2017-05-09 02:00:22

A lot of this comes down to how you envisage the base...

My vision of the base is of three types of hab: (a) the original landers/ascent vehicles (probably only for emergency use) (b) inflatable habs on the surface and (c) Mars ISRU-constructed habs (mainly cut and cover in the early stages). I also envisage there being multiple habs (especially inflatable habs, probably 3 on Mission One) to begin with. I think this offers a number of advantages in terms of versatility and safety.

This also has to do with my overall architecture which incorporates pre-landing in relatively small loads of under 5 tonnes.

So it's in that context that I favour the idea of small pressurised rovers which would be essentially short range taxis, operating on clear flattish ground. There would be the issue of dust that would have to be dealt with...we might possibly have a split air lock (same pressure but split by a curtain of some kind with a portal for attachment to a Rover cabin exit door) to allow for a dust zone (which would be periodically cleaned) and a dust-free zone before you reach the air lock door.

kbd512 wrote:

louis wrote:
Ah well suond like you are thinking of something bigger than I was - I was thinking more of a "tuk tuk" type vehicle, albeit pressurised. I wanted to keep the Base Rover small so it could easily pass through air lock doors, rather than people having to get out of vehicles in space suit breathing from carried cylinders, or - alternatively - having to design special systems for vehicles to lock on to air locked chambers. However, if there was some sort of hatch system that didn't add too much cost and complexity, that might work. But I don't think we need a huge vehicle for moving around the base, in fact would be a disadvantage as it would represent a safety risk.
We probably need a transport hab on the outskirts of the base where the larger Rovers (the ones used for exploration and mining) can be stored while the smaller ones ply between the pressurised habs.
For the Base Rover design, anything lighter and smaller would be good. As I suggested we don't necessarily need windows if we have external camera to internal screen (ECTIS - there you go, a new acronym). I think we need speed governed to no more than 5MPH and probably need to import one of those mini-laser signalling devices you find on most cars now, so the Rover would come to an immediate halt if it is approaching a collision.
For a taxi service, the essential requirement is no EVA. If a hatch attachment works better (no need for dust treatment) I've no problem with that.
If I understand this correctly, the rover has to fit through an airlock designed for humans because you don't want a special air lock for the rover to use and you don't want people to have to EVA to get into the vehicle. I can think of a way to give you two but not three of the design criteria you wanted, so which two are most important?
.For the rover to seal to the airlock, it must be bigger than the airlock so it's not going through an airlock designed for humans. I can make it a lot lighter using wheels and inflatable fabrics, but something has to give

elderflower · 2017-05-09 04:22:30

Airlocks will need an airshower using high velocity jets to remove the bulk of the dust from the outside of a suit and a collection system. Water wash will then be needed (I'm assuming that water will be precious and consumption will be minimised) to remove the remainder. A contaminated water recovery unit will be needed. After that the airlock atmosphere can be replaced with a breathable mix and pressure equalised with the hab. The suit can now be removed and placed in the internal cleaning facility and the astronaut can remove her undergarments, place them in the washing facility and shower herself. She will take a clean gown and then will be able to enter the hab. That's when there is no emergency and no question of bends developing. Further protocols must be generated for stretcher crews and patients and for prolonged waits in the airlock.

kbd512 · 2017-05-09 09:18:40

Louis,

To begin with, there's no absolute control over where anything lands. A few hundred yards one way or another and the landing site may be a debris field. However, I basically thought the same thing you did as far as a base is concerned. The initial landed masses of the things I wanted to deliver were about 5t, with the only exception being ascent stages capable of autonomous propulsive landing.

For a rover to have any real utility, it has to be capable of more than what an astronaut on foot is capable of or it begs the question as to why, with development and delivery prices being what they are, we would pay to use something so expensive with such limited utility. With that in mind, I considered a 5t pressurized tracked rover to be a minimally capable vehicle that provides real utility and protection to its crew.

I limited individual exploration crews to two people so that existing Falcon Heavy rockets could deliver entire mission hardware architecture components in a single shot using chemical propulsion rockets. The recent upgrade to Falcon Heavy lift capability only made what I planned to do easier. I posited that multiple pairs of astronauts could be sent per opportunity and that six crew members split between three complete mission hardware packages would be sent.

As more capable rockets or more advanced propulsion became available, delivered tonnages would increase. Initially, delivered tonnage would range between 5t and 10t.

elderflower · 2017-05-09 12:57:39

Given the requirements for an airlock I don't think a pressurised rover is going to be practical. I believe the open buggy type, with suited explorers, will be more realistic, at least for the first few missions.

Dook · 2017-05-10 20:38:50

louis wrote:

I posted this under a thread which was really intended for larger more robust rovers, so thought I would start a new thread.
This is concerning a 98% Mars ISRU Rover design, specifically a design for a small one or two passenger Rover, to be used exclusively around the base on stone-free ground, for transport from one hab to another.
Having watched some You Tube vids of kids bulding Go Karts, I thought this would be well within the capacity of an early settlement.
I was thinking about it having the following features:
- Solid steel frame or steel tube frame. (Would steel tube allow for air heating?).
- Steel spring suspension.
- Chemical battery
- Electric motor
- Drive shaft
- Aluminium wheels or caterpillar tracks.
- Pressurised cabin constructed from honeycomb aluminium and with a basalt rockwool insulation layer (contained in a steel frame). Will have a single small air lock door.
- Cabin air supply system operating off gas cylinders. Good for 60 mins. Most journey times will be less than 5 mins (passengers will also carry emergency air supply on their person).
- Cabin would have its own battery operated heating system.
- No steering wheel column . Front wheel drive to be operated by radio control on a games console style device affixed to the inside of the cabin.
- Cabin to include either a narrow, thick pressure-proof windscreen with dust blowers to keep the windscreen clear, or to be driven by a camera/video screen system with no windows.
- Headlights operating off their own batteries. Brake lights not required. Only one vehicle will operate on the base for safety reasons.
- Max speed - 5MPH. No gears.
Some questions:
In what temperature range could such a vehicle operate? I'd like it to be able to operate in winter (during the lightest hours of the sol - not at night) as well as in summer.
Would caterpillar tracks work all right on Mars on fairly flat ground?

If the trips were kept to only 5 minutes the rover could have one lithium-ion battery.

The electric motor could be 10 hp and go to a golf cart type axle that powers both rear wheels. No driveshaft needed.

Why the pressurized cabin? Is it because you think the crew would be able to drive from one pressurized habitat to another using this rover? It seems you want multiple surface pressurized habitats. If so, why not just build them close together and have short hallways connecting them so no need to get in a rover and go through an airlock.

If you wanted to drive the rover through an airlock door the door would have to be incredibly strong. Your habitat could never be pressurized to 14 lbs psi, even at 2 psi the force on the door would be 8,640 lbs.

The cabin would have a battery operated heating system? Using electricity for heating uses a lot of watts. A small room heater uses 1,500 watts an hour but if you only want to use it for 5 min that would be fine. I don't think it would be needed since the vehicle would be left inside a warm pressurized habitat and driven for 5 min to another warm pressurized habitat.

You wanted radio controlled steering because you didn't know how to get the steering column through the pressurized cabin without there being a leak. There are seals that work.

What temperature range could such a vehicle operate? If you're just driving from a warm hab to another warm hab and spending only 5 min in the Martian cold there's no problem. The only cold problem you might have would be the battery freezing if you left it out.

Would caterpillar tracks work on Mars? Yes, but tracks use more energy than wheels. I think the wheels should just be shaped like the bracket symbol [ and 1.5 feet wide, maybe even 2 feet wide, so they don't sink in deep sand.

louis · 2017-05-11 04:13:54

Dook wrote:

If the trips were kept to only 5 minutes the rover could have one lithium-ion battery.

Yes, it could be low powered, but I guess we have to plan for the unexpected...the air lock malfunction that keeps them out in the open for an hour say.

Dook wrote:

The electric motor could be 10 hp and go to a golf cart type axle that powers both rear wheels. No driveshaft needed.

Yes, we shouldn't need four wheel or front wheel drive at base where the ground will be level and free of obstructions.

Dook wrote:

Why the pressurized cabin? Is it because you think the crew would be able to drive from one pressurized habitat to another using this rover? It seems you want multiple surface pressurized habitats. If so, why not just build them close together and have short hallways connecting them so no need to get in a rover and go through an airlock.

I think health and safety are paramount. While there are risks to having multiple habs with journeying between them, they should not affect more than a third of the people at a time. If you connect up all habs, a fire, explosion,pressure event or disease factor like mould could affect the whole settlement and, in the worst case scenario, kill off the whole community.

Dook wrote:

If you wanted to drive the rover through an airlock door the door would have to be incredibly strong. Your habitat could never be pressurized to 14 lbs psi, even at 2 psi the force on the door would be 8,640 lbs.

I presume the pressure gradient can't be worse than in LEO, so something that strong. I am thinking of a narrow vehicle, more the width of a very large person than a big automobile.

Dook wrote:

The cabin would have a battery operated heating system? Using electricity for heating uses a lot of watts. A small room heater uses 1,500 watts an hour but if you only want to use it for 5 min that would be fine. I don't think it would be needed since the vehicle would be left inside a warm pressurized habitat and driven for 5 min to another warm pressurized habitat.

Maybe a heater with a connected storage brick, so the heat can be stored (using "mains" electricity" while the vehicle is not in operation). Again my concern would be where an emergency situation resulted in the vehicle being stationary outside for something like an hour.

Dook wrote:

You wanted radio controlled steering because you didn't know how to get the steering column through the pressurized cabin without there being a leak. There are seals that work.

My aim here was really to think of the simplest design so as to facilitate movement between habs, so as to simplify manufacture as far as possible. The aim is to have something that is 95% or higher by mass - maybe 98% - constructed from Mars ISRU resources. So that does suggest a keep it simple strategy. However, if a steering column with Mars-made seals is possible, then I have no problem with that.

It might be that there are simpler methods...perhaps we could have winch systems from one hab airlock to another. But I am not sure how the winch/airlock interface would work. Or if we can have effective seals, perhaps human cycle power would be better or something like those human powered rail maintenance platforms that travel the rails. Are there any ways you could impart human power to the wheels without a direct attachment from the cabin...maybe there is someway through a rocking motion with the crew pushing and pulling weights?

They only need to go about 1MPH for such a system to be effective - still only about 4-7min for 100-200 metre journeys.

Dook · 2017-05-11 09:55:31

louis wrote:

Dook wrote:
If the trips were kept to only 5 minutes the rover could have one lithium-ion battery.
Yes, it could be low powered, but I guess we have to plan for the unexpected...the air lock malfunction that keeps them out in the open for an hour say.
Dook wrote:
The electric motor could be 10 hp and go to a golf cart type axle that powers both rear wheels. No driveshaft needed.
Yes, we shouldn't need four wheel or front wheel drive at base where the ground will be level and free of obstructions.
Dook wrote:
Why the pressurized cabin? Is it because you think the crew would be able to drive from one pressurized habitat to another using this rover? It seems you want multiple surface pressurized habitats. If so, why not just build them close together and have short hallways connecting them so no need to get in a rover and go through an airlock.
I think health and safety are paramount. While there are risks to having multiple habs with journeying between them, they should not affect more than a third of the people at a time. If you connect up all habs, a fire, explosion,pressure event or disease factor like mould could affect the whole settlement and, in the worst case scenario, kill off the whole community.
Dook wrote:
If you wanted to drive the rover through an airlock door the door would have to be incredibly strong. Your habitat could never be pressurized to 14 lbs psi, even at 2 psi the force on the door would be 8,640 lbs.
I presume the pressure gradient can't be worse than in LEO, so something that strong. I am thinking of a narrow vehicle, more the width of a very large person than a big automobile.
Dook wrote:
The cabin would have a battery operated heating system? Using electricity for heating uses a lot of watts. A small room heater uses 1,500 watts an hour but if you only want to use it for 5 min that would be fine. I don't think it would be needed since the vehicle would be left inside a warm pressurized habitat and driven for 5 min to another warm pressurized habitat.
Maybe a heater with a connected storage brick, so the heat can be stored (using "mains" electricity" while the vehicle is not in operation). Again my concern would be where an emergency situation resulted in the vehicle being stationary outside for something like an hour.
Dook wrote:
You wanted radio controlled steering because you didn't know how to get the steering column through the pressurized cabin without there being a leak. There are seals that work.
My aim here was really to think of the simplest design so as to facilitate movement between habs, so as to simplify manufacture as far as possible. The aim is to have something that is 95% or higher by mass - maybe 98% - constructed from Mars ISRU resources. So that does suggest a keep it simple strategy. However, if a steering column with Mars-made seals is possible, then I have no problem with that.
It might be that there are simpler methods...perhaps we could have winch systems from one hab airlock to another. But I am not sure how the winch/airlock interface would work. Or if we can have effective seals, perhaps human cycle power would be better or something like those human powered rail maintenance platforms that travel the rails. Are there any ways you could impart human power to the wheels without a direct attachment from the cabin...maybe there is someway through a rocking motion with the crew pushing and pulling weights?
They only need to go about 1MPH for such a system to be effective - still only about 4-7min for 100-200 metre journeys.

You don't like the idea of connecting multiple habitats because of the risk of fire, explosion, or pressure event, or disease like mold? The risk of fire would be low, an electrical fire would probably be the only way that could happen since there would never be any flammable gasses inside the habitat. All electrical devices would have fuses that would prevent over voltages.

An explosion can only happen if you have flammable gasses. There won't be any.

A pressure event could happen if the habitat vacuum pump over pressurizes the habitat, the warning system somehow fails to warn the crew (because it's pressure switch fails) and the safety over pressure relief valve fails to open to release the building pressure. If that happened the pressure hatch seal would probably blow out and you would lose all pressure in a few minutes. In that case the crew would have to get to their Mars Suits immediately and fix the problem. It's possible but probably has a very low chance of happening because three things would have to fail, the pressure switch that controls the vacuum pump, a pressure relief valve, and the pressure warning switch. Pressure relief valves are simple, a valve with a spring that opens when the pressure gets over 5 psi. It's not likely to fail.

There could be a disease like mold? There isn't any mold on Mars. All the plants would be shipped as seeds but it's possible that some of the seeds could have mold on them. In that case those seeds would be thrown away, discarded outside on the surface.

The electric heater is just in case the small rover got stuck outside for an hour or so? In day time the temperature on Mars near the equator can reach 70 degrees. If there were driving at night and broke down, then they would be need the heater. No one should be outside the habitats or the Long Range Rover at night.

The seal for the steering column would be about a 1" wide circle. If you can't ship that small item to Mars then we can't go.

SpaceNut · 2017-05-11 17:27:01

Things to decide on is in regards to axel road clearance, wheel base length, Width of the wheel base plus wheel tires width in order to design what is want to go through a standard sized air lock....

My first thoughts are to ship such a put, put car is inside a cygnus that would be laid flat onto the ground surface with a means created for the second air lock door to connect up to the habitat space.

louis · 2017-05-11 18:09:05

Dook wrote:

You don't like the idea of connecting multiple habitats because of the risk of fire, explosion, or pressure event, or disease like mold? The risk of fire would be low, an electrical fire would probably be the only way that could happen since there would never be any flammable gasses inside the habitat. All electrical devices would have fuses that would prevent over voltages.
An explosion can only happen if you have flammable gasses. There won't be any.

Really? I think most people here assume we are going to be doing some interesting stuff on Mars. Interesting stuff = flammable gases somewhere.

Dook wrote:

A pressure event could happen if the habitat vacuum pump over pressurizes the habitat, the warning system somehow fails to warn the crew (because it's pressure switch fails) and the safety over pressure relief valve fails to open to release the building pressure. If that happened the pressure hatch seal would probably blow out and you would lose all pressure in a few minutes. In that case the crew would have to get to their Mars Suits immediately and fix the problem. It's possible but probably has a very low chance of happening because three things would have to fail, the pressure switch that controls the vacuum pump, a pressure relief valve, and the pressure warning switch. Pressure relief valves are simple, a valve with a spring that opens when the pressure gets over 5 psi. It's not likely to fail.

Or your Rover slams into a hab at speed. I just mention that so as to point out that we can't really know all the risks. Maybe someone goes loco and deliberately tries to break the pressure seal...who knows? We just know a pressure event is possible.

Dook wrote:

There could be a disease like mold? There isn't any mold on Mars. All the plants would be shipped as seeds but it's possible that some of the seeds could have mold on them. In that case those seeds would be thrown away, discarded outside on the surface.

I am partly basing this on the Biosphere experience and also on advice from hydroponic manufacturers. It's true humans on Mars will be working in a very clean environment but from a bug's point of view that just means "A whole lot of space for me"...

I have read up on people talking about Mars rover missions and so on. They have to admit that the likelihood is that there is contamination before a robot rover heads off to Mars. So the likelihood is that on Mars the pioneers will take something with them whether they want to or not...but the difference is the humans will be in that nice warm, moist environment we like - and which bugs, mould or whatever like also. So you can't pretend this isn't a potential problem. If it becomes a life threatening problem and you only have one hab, well then you potentially have a Mission-destroying scenario.

Dook wrote:

The electric heater is just in case the small rover got stuck outside for an hour or so? In day time the temperature on Mars near the equator can reach 70 degrees. If there were driving at night and broke down, then they would be need the heater. No one should be outside the habitats or the Long Range Rover at night.

I think that figure of 70 is an all time high and for summer. Most of the time we are talking Antarctic and worse. In terms of the sort of "taxi" rovers I am talking about I would not expect them to be operating other than late morning and early to mid-afternoon. Probably just early afternoon in winter.

Dook wrote:

The seal for the steering column would be about a 1" wide circle. If you can't ship that small item to Mars then we can't go.

It would have to be fail-safe... maybe three seals?

Dook · 2017-05-12 07:28:32

You think the settlers are going to make methane? Not in the habitat they're not. That would be like bringing gasoline inside your house so you can mess around with it. Any Sabatier processing would be done in a completely separate module by a machine.

There would be small amounts of methane in the habitat from the humans but the activated charcoal filters should take care of that.

A rover could slam into a hab at speed? Uhh, okay, if it's on the surface.

We can't really know all the risks? We kind of do know all the risks that's why we're taking years to study the problems and find solutions.

There is contamination on robot rovers? Other than the very extreme bacteria any other bacteria on a robot rover would die on the space trip over or die on Mars.

Could there be some kind of bacteria on something that makes it into the habitat? Sure, there could but it's not going to be any different than the Earth and we're not over run with bacteria problems here.

kbd512 · 2017-05-12 19:09:27

If low-speed tracked rovers are used, the likelihood of damaging a habitat is exceptionally low. The power-to-weight ratio of most passenger vehicles greatly exceeds that of the tracked rovers I had in mind and rolling resistance is higher for tracked vehicles. If you let off the accelerator pedal, tracked vehicles quickly roll to a stop. If that fails, cut the power to the motors and you're definitely going to stop. Add in magnetic braking and you have a rover that can stop extraordinarily quickly.

If the rover will only make 5 minute trips around the base, then the most obvious solution is to skip the rover entirely and use suit ports. This is a technology NASA is actively developing. If the next pressurized module is only 5 minutes away at walking speeds, then this is the simplest way of transporting people between pressurized modules.

Alternatively, a base rover should adequately protect its crew from the radiation environment (surprise CME's) and perform multiple tasks well (earth moving, personnel transport, and cargo transport). This presumes personnel and cargo flights land a few kilometers away to prevent off-target landings from damaging base equipment or killing base personnel. There should probably be designated landing areas, maybe as far as 10km away from the base. This rover would transport suited personnel in its cargo hold back to base.

Features List:

A. Motive power from electric motors and batteries (recharged by base power) or super capacitors (recharged by a RTG)
B. Titanium alloy chassis, stainless steel tracks, low Tg metallic rubber for road wheels and track pads, PE foam or hydrogenated BNNT liner for radiation protection
C. Low center-of-gravity to minimize the possibility of rolling the vehicle and improve earth moving capabilities
D. Good traction to reduce the possibility of getting stuck in soft ground or sliding on inclined surfaces
E. Pressurized cabin to permit the operators to remove their space suit helmets
F. Functionality unlimited power for life support functions, which basically means an onboard RTG for electrical power and thermal control
G. Advanced optoelectronics for searches and driving at night, which means thermal imagers and night vision equipment
H. iPad-like touch-screen displays to monitor vehicle status and the outside environment using onboard sensors and optoelectronics
I. Simple inward-opening mechanical hatches; crew enters and exits by climbing atop the vehicle

An Earth-bound Vehicle with Desired Performance Characteristics:

The 8,000kg Japanese Type 60 106mm Recoilless Rifle Carrier has a power-to-weight ratio of .01375kW/kg using its 110kW diesel engine and a top road speed of about 55kph. The same vehicle weighs 3,040kg on Mars, so it requires 42kW or 55hp to achieve a power-to-weight ratio of .01381kW/kg. If the vehicle is made from Titanium alloy (Ti-6Al-4V), the Komatsu diesel engine is replaced with electric motors, and the weapons are eliminated, I estimate the mass to be 5,000kg on Earth or 1,900kg on Mars. Using a 27kW or 36hp motor, power-to-weight ratio is .01394kW/kg. Two 18hp electric motors are sufficient to provide slightly better PWR than the Earth-bound vehicle.

The Japanese Type 60 weapons carrier is 4 feet 6 inches in height, 7 feet 4 inches wide, and 14 feet 1 inch in length. The Mars bound vehicle will be less than 4 feet high because it won't mount weapons or outward opening hatches. The cargo area is sufficient for four suited crew members in reclined positions, additional battery packs for extended range operations, a water tank, consumables, or other small cargos like spare parts. It's powerful enough to operate over rough terrain, light enough to deliver with current chemical rockets like Falcon Heavy, and small enough to drive under a Mars habitat module.

Assuming an electrical power consumption rate of about 13.4kW/hr, that means 53.6kWh for 4 hours of use, so 70kWh capacity battery provides the desired capacity. That equates to about 10.5 of the 5.3kWh Tesla EV battery packs. By substitute the 12 packs from the Marscat, for a total of 660lbs of batteries, the vehicle has a power reserve past its 4 hour operating limit. At an average speed of 25kph, this equates to a 50km driving radius, so approximately 7,854km^2 of useful exploration capability. A roof-mounted solar panel could potentially provide site power during day excursions associated with drilling operations attempting to locate ice. External connections could provide suit power for laborious physical activities like setup of drilling equipment.

Japanese Type 60 C Model Performance Notes:

The 110kW turbo diesel is erroneously listed as a 6 cylinder air-cooled turbo diesel by Wikipedia, but it's actually a 4 cylinder Komatsu S4D-102 water-cooled turbo diesel. The "6T-120-2" nomenclature is a reference to a heavier, less powerful 6 cylinder air-cooled engine fitted to the A model vehicles in the late 1950's trials. Other sites list the engine as SA4D-105, but the 4D-105's make 90hp or less.

Komatsu 4D-102

Komatsu 4D-105

Last edited by kbd512 (2017-05-12 19:10:32)

SpaceNut · 2017-05-12 20:08:05

I am sold on the use of the RTG and wondered if a tray of super capacitors being made removable is worth the effort to create a portable power source for in a pinch when required.

The advance optics are also a good feature as the human eye can only see so much plus it can eliminate the need for glass windows to drive the vehicle with as you are suggesting more advanced electronics for vehicle monitoring and more I hope.

As we send mission the size of the vehicle can grow from the smaller 1 to 2 seater to 4 or 6 with the finally version being much larger for mass transit.

I like the thought to use the vehicle for more than just transport of science as adding drilling will make it possible for the future as man must have water at the least power, energy used to get it.

kbd512 · 2017-05-12 23:06:36

SpaceNut,

The super capacitor / RTG power source requires a homopolar generator (HPG) connected to the RTG. The RTG makes electricity from the Seebeck effect to spin the HPG, the HPG produces otherwise unusable output to charge the super caps, and the super caps either provide bursts of power or regulated output to drive an electric motor or charge a battery.

For mobile power, a hand cart to hold the RTG, super caps, and/or batteries is required. A folding cart using Wheeleez Polyurethane tires that won't sink into the sand might work, but might also need some sort of heat source. The RTG, super caps, and batteries are inserted or removed via top loading trays in the Type 60 Model M (for Mars, of course). The user must stand atop the vehicle, straddle the tray, and pull up vertically with both hands. Some sort of thermal protection is required for handling the hot RTG. I was thinking CarbonX gloves since the material provides superb thermal and electrical insulation.

Although the Type 60 M seats 2 people in the pressurized cabin and 4 suited people in its unpressurized cargo hold, the unpressurized variant seats up to a dozen people in its unpressurized cargo hold. The unpressurized variant provides pressurization only when a fabric pressure vessel is inserted into the cargo area, thermal control, radiation protection, and is self-powered, but has no dedicated crew compartment. The pressurized rover would typically be connected to the unpressurized rover, much like the Hagglunds BV206. A dedicated cargo carrier chassis variant could transport fission reactors, WAVARs, fluid tanks (H2O, LOX, LH2, LN2, CO2, or CH4), batteries, and other consumables like food.

Liquid CO2 tanks would be required to use air-powered tools. H2O, LOX, and LN2 are obviously required by humans. LOX and CH4 are obviously rocket propellants.

SpaceNut · 2019-10-24 18:55:36

Going with a home built might work but driving a Telsa unit car would be the bomb of a drive but its going to be all batteries without the means to keep them warm and thats a problem as the garage is yet to be built to house it from the weather of mars

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