Author Topic: Designing a Solar Power Rover Waystation  (Read 2241 times)

Online rakaydos

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Designing a Solar Power Rover Waystation
« on: 12/25/2018 12:27 am »
Premice: SpaceX has put out a bid for a rover recharging station, to be carried away from the initial landing site, set up by rover, and then left on it's own until a (Model X chassis based) rover comes by, either needing a supercharge, or needing additional power to keep the heaters running during a dust storm. Designs will be graded based on practicality, Additional science capability, and alignment with spaceX's future mars ambitions. (read- someday people will be on mars, how will this be useful to them. Mass limit is 5 tons if carried as cargo, more if it functions as a trailer for a rover.

What would you design for this bid?
« Last Edit: 12/25/2018 12:34 am by rakaydos »

Offline nacnud

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Re: Designing a Solar Power Rover Waystation
« Reply #1 on: 12/25/2018 12:48 am »
Pretty much this by Renova gen


Online rakaydos

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Re: Designing a Solar Power Rover Waystation
« Reply #2 on: 12/25/2018 12:51 am »
My own approach would be for a "roll-on" charge platform, with  clearly placed passive guides for autonomus rovers to reach the charge point. Solar arrays would roll out  from two opposite sides, battery pack would be under the ramp. The charging stand would double as a basic weather station and radio relay, have a StarlinkMars antenna, and if mass permits, be able to ISRU oxygen to at least refill personal tanks, of not entire rover tanks. Behind a closed panel is a manual screen and keyboard (oversized keys for spacesuits) for troubleshooting the OS in person or sending emergency messages.

Offline oldAtlas_Eguy

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Re: Designing a Solar Power Rover Waystation
« Reply #3 on: 12/25/2018 01:43 am »
Additionally use an inductive charging so connectors are not used. Plus the inductor can also carry a signal if needed in case of WiFi failure.

Offline MickQ

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Re: Designing a Solar Power Rover Waystation
« Reply #4 on: 12/25/2018 10:42 am »
I'd also include an airtight room containing emergency first aid and suit repair kits, spare suit batteries and maybe gloves and a helmet.  It would be large enough for a person to strip off a spacesuit if required to conduct emergency repairs to body and / or suit. Also water and O2.

Online rakaydos

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Re: Designing a Solar Power Rover Waystation
« Reply #5 on: 12/25/2018 03:48 pm »
I'd also include an airtight room containing emergency first aid and suit repair kits, spare suit batteries and maybe gloves and a helmet.  It would be large enough for a person to strip off a spacesuit if required to conduct emergency repairs to body and / or suit. Also water and O2.
Would it be better as an inflatable emergency shelter, ("Pop tents" from the Martian) rather than a separate "airtight room?" I'm imagining that it isnt intended for reular use, only emergency use, so it's probably something that should be low maintinace under sandstorm conditions until it's actually needed.

Also, why spare suit batteries, when you can recharge the batteries they already have?

Offline MickQ

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Re: Designing a Solar Power Rover Waystation
« Reply #6 on: 12/26/2018 07:52 am »
Emergency use only. The way I see it, a pop tent needs to be deployed before a person enters thru, I assume a lock of some sort.  This takes time.  With a fixed room you would enter, shut the door, pull a lever and have a breathable atmo in a matter of seconds.

Batteries for a quick change in event of an unexpected power drain or a battery failure.  Swap n go !


Offline Slarty1080

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Re: Designing a Solar Power Rover Waystation
« Reply #7 on: 12/26/2018 12:27 pm »
The basic trade off here is the quantity of solar panels v the quantity of batteries. More panels means faster recharge time more batteries means greater recharge capacity. If intended only for occasional use, I would include an excess of batteries over panels.

The vehicle needing changing would approach the charging station and position itself over a flat piece of ground and plug into the charging station. If the need was just for additional power the vehicle could draw what it wanted from the stations batteries. Alternatively the vehicles battery pack could be lowered to the ground, the vehicle driven a short distance forward over a fresh battery pack and the new pack could then be raised up into the bottom of the vehicle. The vehicle would then unplug and continue on its way. The next vehicle would approach from the opposite direction and do the same thing.

A small trailer would be provided capable of having multiple batteries packs loaded into it in a similar fashion so that power packs could be distributed to a remote site (eg broken down vehicle now repaired but low on power).

A further trailer would be provided to carry the panels from which the panels could be loaded or unloaded automatically using some sort of unfolding mechanism. So the whole charging station could be moved wherever it was needed and when it is no longer needed it could simply be used as an additional power source for a base.
The first words spoken on Mars: "Humans have been wondering if there was any life on the planet Mars for many decades well ... there is now!"

Online rakaydos

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Re: Designing a Solar Power Rover Waystation
« Reply #8 on: 12/26/2018 01:21 pm »
The basic trade off here is the quantity of solar panels v the quantity of batteries. More panels means faster recharge time more batteries means greater recharge capacity. If intended only for occasional use, I would include an excess of batteries over panels.
An interesting perspective. Given that one of the objectives is to keep a rover alive (electronics not frozen) in a multi-month 90% dust storm, that would seem to suggest a minimum solar panel quantity. At the same time, if irregularly used, you are going to be sitting at full batteries quite often, and would want to have it be doing something useful with the excess solar power in good weather.

In other threads I suggest atmospheric water collection + an ice cube machine, dumping ice into a pile in the shade of the solar panels, as a method to turn transient solar power into useful resources- lossy due to sublimation, but no hard cap on storage like something tank-limited.

Offline Slarty1080

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Re: Designing a Solar Power Rover Waystation
« Reply #9 on: 12/26/2018 05:14 pm »
The basic trade off here is the quantity of solar panels v the quantity of batteries. More panels means faster recharge time more batteries means greater recharge capacity. If intended only for occasional use, I would include an excess of batteries over panels.
An interesting perspective. Given that one of the objectives is to keep a rover alive (electronics not frozen) in a multi-month 90% dust storm, that would seem to suggest a minimum solar panel quantity. At the same time, if irregularly used, you are going to be sitting at full batteries quite often, and would want to have it be doing something useful with the excess solar power in good weather.

In other threads I suggest atmospheric water collection + an ice cube machine, dumping ice into a pile in the shade of the solar panels, as a method to turn transient solar power into useful resources- lossy due to sublimation, but no hard cap on storage like something tank-limited.
Yes its a complex issue with many variables. How much light is received during a dust storm? How long do they last on average? How much power is needed to stop freezing? How much weight for batteries, panels and auxiliary equipment like trailers and ice cube machines?

I did wonder if a solar sat would be useful. Could double the power available and minimise the effects of dust storms if a suitable frequency for power transmission was used. But there would be a fairly high overhead from all of the additional equipment so I thought it wasn't practical for a 5 ton station.
The first words spoken on Mars: "Humans have been wondering if there was any life on the planet Mars for many decades well ... there is now!"

Online rakaydos

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Re: Designing a Solar Power Rover Waystation
« Reply #10 on: 12/28/2018 12:24 pm »
Saw this elsewhere, thought I'd raise it for discussion.

Id like to see some small 5g cell towers deployed with those distributed charging stations and some drones for advanced reconnaissance. Once you have a few small charging stations distributed around the base station, drones could cover hundreds of miles and find promising locations for rovers to follow up on.
Im guessing Elon will deploy a small starlink satellite system for ground support and relay back to earth. 5g chips will be smaller than starlink and needed for device connectivity and starlink would be for base station and larger rovers.

Offline Slarty1080

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Re: Designing a Solar Power Rover Waystation
« Reply #11 on: 12/28/2018 01:50 pm »
Saw this elsewhere, thought I'd raise it for discussion.

Id like to see some small 5g cell towers deployed with those distributed charging stations and some drones for advanced reconnaissance. Once you have a few small charging stations distributed around the base station, drones could cover hundreds of miles and find promising locations for rovers to follow up on.
Im guessing Elon will deploy a small starlink satellite system for ground support and relay back to earth. 5g chips will be smaller than starlink and needed for device connectivity and starlink would be for base station and larger rovers.
I would have thought a Martian version of geostationary orbit would be preferable initialy - one sat always visable for hundreds if not thousands of km.
The first words spoken on Mars: "Humans have been wondering if there was any life on the planet Mars for many decades well ... there is now!"

Online rakaydos

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Re: Designing a Solar Power Rover Waystation
« Reply #12 on: 12/28/2018 03:44 pm »
That may still be a Starlink bus sitting at martian geosynch (which will be significantly closer- 62% closer? than earth geosynch) but I probably should have cropped the quote better. I was raising the idea of an "aviary" version of the waystation, where a drone could safely land and charge, and relay data through to the main network.

Offline Cheapchips

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Re: Designing a Solar Power Rover Waystation
« Reply #13 on: 12/29/2018 01:50 pm »
One of the engineers who designed the Dragon solar panels is now designing origami furniture.  In this Reddit thread he also mentions the ITS fans, although can't spill any new info. 

https://v.redd.it/775ffn3uzxx11

Since the same team is still at SpaceX, maybe we'll end up with some very space efficient pop up structures for panels and charge stations.
« Last Edit: 12/29/2018 01:51 pm by Cheapchips »

Offline Paul451

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Re: Designing a Solar Power Rover Waystation
« Reply #14 on: 12/29/2018 03:15 pm »
Short discussion of way-stations on the Envisioning Amazing Martian Habitats thread. (I also riffed on the idea of using Methane/LOx with ICE engines on rovers, due to the higher energy density over batteries. Was not a popular suggestion.)



a (Model X chassis based) rover

While SpaceX is pragmatic enough to use OTS systems instead of bespoke ones, they aren't obsessive about it. The cost of modifying a Tesla chassis to work on Mars (cold, near vacuum, etc) almost certainly outweighs any savings from not designing a more suitable general-purpose rover chassis.



Pretty much this by Renova gen

I find it odd that they deploy it that way, dragging the whole length over the ground. (Same again when you wind it back up.) A small change would eliminate that, just have the solar array deploy out the back of the trailer instead of the side. That allows you to anchor the end down and then drive the trailer away, letting the array unroll but not dragging it over the ground. Surely that would reduce damage to the panel over time?

[edit: Argh. Is there a way to turn off auto-embedding of youtube links?]
« Last Edit: 12/29/2018 03:16 pm by Paul451 »

Offline Paul451

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Re: Designing a Solar Power Rover Waystation
« Reply #15 on: 12/29/2018 03:29 pm »
Pulling together different pieces that people have mentioned:

I think way-stations would evolve as the activity on Mars changes. Starting out as merely a recharge station for autonomous rovers, with a weather and comms system to use any spare power. Indeed, the first "way-station" would be the rover hub at the main landing site itself. The second would be at the site of the first settlement, a modest distance from the landing site since you don't want them too close, which means rovers have to be able to charge at either end.

As activity increases, especially as humans arrive, you add some features for larger rovers. For example, the battery packs used in the way-stations should be the same as the packs in the larger rovers, so you can swap them out. Not necessarily easily or automatically at this early stage, but just so the options for maintenance are increased. Likewise, basic electronics like the comms system would be the same in the rovers and the way-stations. You want to avoid "square peg into a round hole" situations when lives might depend on it.

Gradually you enlarge key stations and add more standard and emergency functions. For example:
An atmospheric water collector, powered whenever the batteries are full, using power that would otherwise be wasted.
An emergency oxygen tank, in a form that is compatible with suits/vehicles, with the splitter and compressor powered when the batteries and the water tanks are full.
A small stockpile of suit and vehicle spares, patches, and a decent set of tools. (Perhaps mounted on a small rover that can be summoned by a trapped crew.)
A nitrogen tank, with extractors and compressors (Mars doesn't have much nitrogen in its atmosphere, but it's there), enough to repressurise your rover once you've repaired the leak.
A pressure chamber, with docking for a rover. As an emergency chamber, it's kept unpressurised, used as an airlock by a suited astronaut. (Get in, seal the door, release the N₂/O₂ from the tanks, let the heaters run, then doff the suit. Basic CO₂ scrubbers (with salvageable parts compatible with vehicle and suits) to extend the life of the air supply in the chamber.)
Add a larger chamber to that, with more facilities and a longer duration ECLSS, which is kept pressurised when not in use, the more basic chamber is then used as an airlock for the larger.

Which way-station gets what add-on also depends on changing activity. For exploration and science by unmanned small rovers, you have the basic solar+battery stations scattered widely. For a main route between two sites (main base and outlying mines) dozens to hundreds of kilometres apart, you have regular stations that build up capacity as the traffic does. For humans travelling those regular routes, you have a handful of larger stations for regular overnight stops; but many more emergency shelters between. (Essentially a suited astronaut should never be more than a few kilometres from a radio, a walkable distance with a mild injury. And no more than a 12hrs walk or 2hr drive from shelter.) Large unmanned cargo-freighters between separated sites would use the smaller way-stations as nav. beacons and comms relays. So the smallest stations along any fixed route would be line-of-sight. With larger stations for the main recharge stops (larger battery banks).

A standard practice might be to recycle older parts into "new" small way-stations at the limits of the existing network. A lot of systems get replaced when they are still functional, but have lost efficiency and aren't worth repairing again. For example, when replacing older battery packs and panels at your main settlements (or upgrading heavily trafficked way-stations), they might be thrown together to add "new" small way-stations out at the edges of low priority areas. Old rovers get re-purposed as way-station rovers. Older pumps and compressors are added to smaller way-stations. When you replace a regularly used pressurisable chamber, you use the old one as an emergency shelter (mostly unused), etc, "upgrading" stations to their next level.

Likewise, every time a science station gets added somewhere, for whatever purpose, you ensure it uses standard parts for the core so that it effectively becomes a new entry-level way-station.

Offline ThereIWas3

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Re: Designing a Solar Power Rover Waystation
« Reply #16 on: 12/29/2018 04:39 pm »
I don't think roll-out PV panels would last through the first dust storm.   Instead, something elevated with a way to flip and dump the dust off.  I have seen pictures of things that look like a carport.  The one in this picture looks to have about 3 KW of PV on the roof (less on Mars).



Clearly there have to be batteries.  Tesla's Earth-tech uses Lithium-Manganese-Cobalt Ion batteries which have all the overheating problems we are aware of.  They have stringent environmental requirements, use rare and nasty chemicals, and employ active liquid cooling.  For unatteneded operation on Mars you want something very reliable with no moving parts, so I would use Lithium-Ferro-Phosphate chemistry instead.
« Last Edit: 12/29/2018 04:41 pm by ThereIWas3 »
"If you want to build a ship, dont drum up people to collect wood and dont assign them tasks and work, but rather teach them to long for the endless immensity of the sea" - Antoine de Saint-Exupry

Offline Paul451

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Re: Designing a Solar Power Rover Waystation
« Reply #17 on: 12/29/2018 05:10 pm »
I don't think roll-out PV panels would last through the first dust storm.   Instead, something elevated with a way to flip and dump the dust off.

Just how thick do you think the dust is?

Offline John Santos

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Re: Designing a Solar Power Rover Waystation
« Reply #18 on: 12/29/2018 09:59 pm »
[...] You want to avoid "square peg into a round hole" situations when lives might depend on it.

You mean "square CO2 absorber in a round ECLSS hole."  Sorry, carry on.

Online AC in NC

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Re: Designing a Solar Power Rover Waystation
« Reply #19 on: 12/30/2018 07:22 pm »
Pulling together different pieces that people have mentioned:

I think Paul451 is onto the right approach here.  You start with the MVP which would be Panels, Batts, and the Electronics package.  Perhaps something ISRU-like if you could do that cheap mass-wise.  Or perhaps feeding power back to the main ship if you can make the units small enough and site them close enough or "losslessly-enough".

The important part would be to modularize you package and interface.   Subseqent packages could be fanned out or daisy chained to establish additional capability.