NASA's planning for Mars human missions - interesting stuff.

louis · 2018-05-26 15:24:13

Some interesting resources here on NASA's planning for a human mission to Mars (from 2015)...

https://www.nasa.gov/feature/mars-human … sentations

(May well have been referenced in part or whole previously.)

Although NASA may no longer be the prospective leaders in planning to send humans to Mars, it's interesting to see their thinking. There's lots there, but here are some highlights:

(1) Potential landing sites (glad to see Chryse Planitia is in there) -

https://www.nasa.gov/sites/default/file … tagged.pdf

(2) Orbital reconnaissance of landing sites (a lot more work done on that than you might have thought) -

https://www.nasa.gov/sites/default/file … tagged.pdf

(3) ISRU/Civil engineering requirements -

https://www.nasa.gov/sites/default/file … ewg_v2.pdf

Re other discussions we've had, I note NASA seemed to be thinking in terms of six person crews, which I also favour.

kbd512 · 2018-05-26 20:11:59

Louis,

There's a lot of good stuff there that I've never seen before. Thanks for posting this.

SpaceNut · 2018-05-26 22:11:10

Ya Thanks Lious,
Started looking in reverse order and of these have these conclusions.
Get and gather data on sites for water from orbit and confirm on the ground.
Demonstrate possible insitu water gathering and processing on earth analogs to be followed up with mars demonstrators.
Moxie is just one of those that will be sent to confirm design demonstration.
The food ananlog is being worked on but when will we have the demonstrator?
We should be making quicker process on getting demonstrators designed and sent to mars as Nasa is at a snails pace....

louis · 2018-05-27 05:30:39

Yes, I think although the planning is good, the slow speed suggests NASA isn't really serious, and perhaps never has been. But maybe they will share their indepth detail with Space X - that would be good.

I am sure Space X will have started on the logistical planning in parallel with the BFR development. They've got about 3 years to get it right (get all the key mission architecture design points in place) if they are going to stick to their ambitious schedule.

SpaceNut wrote:

Ya Thanks Lious,
Started looking in reverse order and of these have these conclusions.
Get and gather data on sites for water from orbit and confirm on the ground.
Demonstrate possible insitu water gathering and processing on earth analogs to be followed up with mars demonstrators.
Moxie is just one of those that will be sent to confirm design demonstration.
The food ananlog is being worked on but when will we have the demonstrator?
We should be making quicker process on getting demonstrators designed and sent to mars as Nasa is at a snails pace....

Last edited by louis (2018-05-27 05:31:09)

louis · 2018-05-27 05:38:34

I am liking this presentation! -

https://www.nasa.gov/sites/default/file … arrell.pdf

This is pretty much what I have been proposing - a mission to Chryse Planitia.

The paper asks: "What is the single most important additional data set needed to
assess the resource potential of the EZ? " and answers "Presence and depth of
water ice deposits." - that's for sure! In fact that's why I think possibly somewhere a bit more north east of the Viking landing zone might be better, given the water signature seems stronger there.

I thought it interesting as well that the presentation asks: "What is the single most important additional data set needed to assess the science potential of the EZ?" and answers " Presence and composition of organic matter." Suggests perhaps NASA folk are more amenable to the idea of life on Mars than they usually suggest.

elderflower · 2018-05-28 04:01:46

Interesting that the illustration on the Civils frontsheet shows a base with a flattened and cleared pad for the ship.

louis · 2018-05-28 09:33:51

Yes, interesting. I guess NASA's slow approach would allow for a number of precursor missions, which might include a robot rover that can create a flattish area.

Will be interesting to see how Space X address the issue. They don't looking for problems, and it will only be a problem on Mission One - thereafter the pioneers can build flat landing areas.

elderflower wrote:

Interesting that the illustration on the Civils frontsheet shows a base with a flattened and cleared pad for the ship.

SpaceNut · 2018-05-28 13:47:53

louis wrote:

Some interesting resources here on NASA's planning for a human mission to Mars (from 2015)...
https://www.nasa.gov/feature/mars-human … sentations
(May well have been referenced in part or whole previously.).

Ok looking at the first link and seeing what we have found seems to me its a checklist of what needs to be done before man can go to mars as well as must be done to make sure we can survive if we did go.
The timeline is decades in the future with goals to which we must be able to demonstrate for man of which we will need power, food, water, air and shelter the means to protect man from trip enviroment, surface conditions all while doing science before heading home.

Each will require demonstrators and then a final integration for success along with lots of test trails to be sure man can be safe before going for the goal of man setting foot on Mars..

louis · 2018-05-28 14:14:06

Re Gale Crater, they have identified a flat area of approximately 25 km square of the terrain with a slope less than ~10 degrees and without significant landing hazards including dust.

https://www.nasa.gov/sites/default/file … tagged.pdf

Perhaps this is the sort of site will be where Musk aims for?

More on Gale Crater as an exploration zone:

https://www.nasa.gov/sites/default/file … tagged.pdf

louis · 2018-05-28 14:25:53

Well that's NASA's way...but Space X clearly intend to accelerate the process.

Space X's large vehicle (multiple, cargo and human bearing) will provide a lot of built in safety I think, simply because of all the back-up it can carry.

We've discussed landing a lot here - but these presentations make clear that NASA think there are potential safe dust-free and fairly flat landing sites. No doubt someone will say the parameters for a BFR will be different but I think there must be suitable sites.

The main issue I think that Space X will need to overcome is propellant production, because that will be a massive task.

SpaceNut wrote:

louis wrote:
Some interesting resources here on NASA's planning for a human mission to Mars (from 2015)...
https://www.nasa.gov/feature/mars-human … sentations
(May well have been referenced in part or whole previously.).
Ok looking at the first link and seeing what we have found seems to me its a checklist of what needs to be done before man can go to mars as well as must be done to make sure we can survive if we did go.
The timeline is decades in the future with goals to which we must be able to demonstrate for man of which we will need power, food, water, air and shelter the means to protect man from trip enviroment, surface conditions all while doing science before heading home.
Each will require demonstrators and then a final integration for success along with lots of test trails to be sure man can be safe before going for the goal of man setting foot on Mars..

Oldfart1939 · 2018-05-28 15:55:34

Louis-
THX for posting these links. It appears that not everyone at NASA is totally brain dead, after all. But this incremental approach they are taking is awfully slow and timid. The schedule they have in place will be getting us off this lovely blue oasis in the universe about the time the Dahlonega Glacier subsumes the Marshall Space Flight center and threatens Cape Canaveral.

All jest side, there remains a lot of exploratory work before the first BFS actually lands, and that should by any reasonable mission architecture--be a 6 , 7, or 10 man mission with a smaller lander with some construction and drilling equipment onboard. We need WATER, and a flat place to land a larger spacecraft such as BFS. Naturally a well-located of landing beacon-transponders should be emplaced by this pioneer mission.

louis · 2018-05-29 16:24:26

I think it is an interesting collection of papers.

It's encouraging to see the extent to which they have matched data to potentional exploration zones. Of course, because it's NASA, they are "exploration" zones and not "settlement" zones. But even so...

They seem to have an agreed methodology in terms of what needs to be in the exploration zone, and I agree pretty much with that framework.

I've yet to see a location that is no further than 30 degrees north or south, that has detectable and exploitable ice, and that has a dust free flat(tish) rock layer for landing...but if there is then that might well be where Space X decide to land (exploitation of resources like iron ore and basalt can wait for later missions - for Mission One it is the water, the landing area and, if you are using PV, the latitude that matter). My point is that if they can find that sweet spot, then the requirement for precursor missions beyond the two cargo landings scheduled for 2022 fades.

Oldfart1939 wrote:

Louis-
THX for posting these links. It appears that not everyone at NASA is totally brain dead, after all. But this incremental approach they are taking is awfully slow and timid. The schedule they have in place will be getting us off this lovely blue oasis in the universe about the time the Dahlonega Glacier subsumes the Marshall Space Flight center and threatens Cape Canaveral.
All jest side, there remains a lot of exploratory work before the first BFS actually lands, and that should by any reasonable mission architecture--be a 6 , 7, or 10 man mission with a smaller lander with some construction and drilling equipment onboard. We need WATER, and a flat place to land a larger spacecraft such as BFS. Naturally a well-located of landing beacon-transponders should be emplaced by this pioneer mission.

SpaceNut · 2018-05-29 17:20:31

louis this document describes what Nasa indicates what we can do and what still needs to be learned https://www.nasa.gov/sites/default/file … tagged.pdf
slide 4
of which Space x has just a launcher and still needs to accomplish some of the learned items as well as finish the not learned on that page.

louis · 2018-05-29 18:57:17

OK, going through those lists of things still to learn from Slide 4:

Orbital Environment and operations

"Return flight from Mars to Earth" - the BFR is credible for that.

"Autonomous Rendezvous & Docking" - not required on the Space X model apart from the Earth orbital fuelling.

"ISRU feasibility" - I don't think that's really required on Mission One, apart from propellant production, in the case of Space X's plan.

"Resource characterization of Mars moons" - completely irrelevant in my view and certainly not required for a Space X mission.

"High-power SEP" - Is that solar electric propulsion? Irrelevant as regards Space X or indeed for probably decades ahead.

Capture, EDL & Ascent at Mars

"Ascent from Mars" - The BFR has that covered, subject to propellant production and loading.

"Large mass EDL" - Probably a lot easier than low mass EDL in my view - apart from the actual landing, which we agree needs a reasonably flat area of stable dust-free ground with not too many large or unstable boulders.

"Precision EDL" - We've debated that a lot. I think laser guidance and topographical guidance systems plus transponders on the cargo landers will provide enough guidance for a precision landing.

"Aero-capture" - The BFR will combine that.

"Site topography and roughness" - Some of the other presentations suggest some people are very confident about their ability to predict ground conditions. I guess you could check that capability to a large extent on Earth.

"Long-term atmospheric variability" - Not sure what that means (is it dust storms?) but I think that is a bit "here there be dragons".

Surface Operation on Mars

"Landing site resource survey" - Obviously we are looking for the best site right from the start but for Mission One the key requirements are a safe landing area and water resources, plus a suitable site for energy production. I would not want to overcomplicate things on Mission One. Keep it simple. With the Space X model, you could land robot rocket hoppers to go explore for better , more resource rich locations if necessary.

"Dust effects on human health, suits & seals" - Again for Mission One, the need for elaborate EVAs should be minimal. In fact an EVA will simply be a PR necessity in all likelihood. NASA must have good info on dust sealing from its robot rovers otherwise they wouldn't have been moving after six months. The large cargo element in the Space X mission design means you can make a big allowance for dust removal, double air locks with integrated showers etc.

"Rad/ECLSS in Mars in environment" - Well, clearly this is something that needs to be prioritised. I can't believe Space X aren't already working on it in great detail (they clearly are already working on life support in relation to the crewed Dragon) though we don't have info on that yet. Radiation is an overstated problem in my view. I think we have all the solutions available.

"Power sufficient for ISRU" - I don't think that will be a problem with the Space X mission which would have 400-500 tonnes of cargo taken along.

"Surface Navigation" - I don't see how this will be a major problem.

So, overall, my verdict is "Looking good Houston" as they used to say!

SpaceNut wrote:

louis this document describes what Nasa indicates what we can do and what still needs to be learned https://www.nasa.gov/sites/default/file … tagged.pdf
slide 4
of which Space x has just a launcher and still needs to accomplish some of the learned items as well as finish the not learned on that page.

Last edited by louis (2018-05-29 18:57:50)

kbd512 · 2018-05-30 06:37:02

Louis,

High-power SEP means 50%+ of your vehicle can be payload and no orbital refueling is required. The transit times achieve parity with chemical rockets in the 600kW to 700kW range. Aerojet-Rocketdyne's X3 thruster will demonstrate 200kWe before the year is through.

Saying "BFR does that" means nothing at this point. BFR doesn't exist yet. You have no clue how BFR will perform and neither does anyone else.

Nobody has built a multi-megawatt power plant on another planet before, so it remains to be seen how well this will work in practice. I have faith in the underlying technologies, but construction of a power plant isn't as simple as rolling out some solar panels. If it was, then it wouldn't take as long to build PV farms here on Earth where manpower is unlimited and nobody is wearing a space suit.

louis · 2018-05-30 11:14:53

kbd512 wrote:

Louis,
High-power SEP means 50%+ of your vehicle can be payload and no orbital refueling is required. The transit times achieve parity with chemical rockets in the 600kW to 700kW range. Aerojet-Rocketdyne's X3 thruster will demonstrate 200kWe before the year is through.

Nothing against SEP. Just not a necessary condition of Mars settlement.

kbd512 wrote:

Saying "BFR does that" means nothing at this point. BFR doesn't exist yet. You have no clue how BFR will perform and neither does anyone else.

It's a bit silly to say "no clue". "Some clue" is what we have. We know how big rockets perform aerodynamically. The rockets engines for the BFR have been tested...though the tests may not yet be finished. We know BFR can land rocket stages and retrieve other parts of rockets. It's engineering and physics, so much easier than trying to determine some other things.

kbd512 wrote:

Nobody has built a multi-megawatt power plant on another planet before, so it remains to be seen how well this will work in practice. I have faith in the underlying technologies, but construction of a power plant isn't as simple as rolling out some solar panels. If it was, then it wouldn't take as long to build PV farms here on Earth where manpower is unlimited and nobody is wearing a space suit.

I think the last thing you should reference is putting together a solar farm on Earth (c 16 weeks). In that case the major consideration is cost. You do it the cheapest way possible. But this is about energy security - it's safety first. I think everything will be pre-cabled up and it will be more of a lego exercise, clicking together the various elements of the PV energy farm. I think they'll have lots of ATK fan PV arrays as well to kickstart energy production. Remember also that on Earth all solar farms have to be built to withstand major wind storms and rainfall. This will not be the case on Mars - where even the worst wind storms are very weak.

We have yet to see what system Space X are working on but I think one idea that might work is to have flexible PV panelling on a roll with the panelling suspended between to lines that can be drawn taut, so the whole assembly can be tilted to the required angle (supported by lightweight frames at intervals).

I will be surprised if the whole assembly cannot be rolled out in a matter of a few sols, with say 10% being available on Sol 1 or 2 via ATK fan arrays or similar.

Last edited by louis (2018-05-30 11:16:09)

kbd512 · 2018-05-30 16:56:00

Louis,

SEP is Mandatory

If launch and maintenance costs and total tonnage delivered are a consideration at all, then yes, SEP is necessary for Mars settlement. It's not a requirement for the first few missions, but a sustainable colonization architecture is required and as cheap as the fuel might be, maintenance is definitely not cheap. The more flights that deliver useful payload versus fuel to go anywhere to do anything, the lower the cost of transport becomes and the more people who can afford to go live on Mars. $250K vs $50K. At $50K virtually anyone in the western world and an increasing number of people in the eastern world can afford to go to Mars. At $50K per person, a corporation can afford to send their scientists to Mars to do research and development projects to improve things like food production, solar panels, batteries, you name it.

SpaceX's Big Rockets and Past Performance

When was the last time you saw a Space Shuttle larger than the orbiter's main tank fly without issue? Since both the Boeing 747 flew and the Airbus A380 flew, that should mean StratoLaunch's Roc can just make sure the engines have gas and then takeoff, right? Falcon Heavy flew six years after Mr. Musk thought it would. Nobody, not even Elon Musk, can snap their fingers and create a Saturn V class multi-stage reusable rocket in two years. That simply will not happen and anyone who is not being incredibly naive should already know that. Four to six years is far more probable and in line with past performance.

Multi-Megawatt Class PV Farms on Mars

I think "pre-cabled up" solar arrays are a really bad idea. The deployment area may not lend itself to that sort of pre-packaged solution. If the ground was graded, leveled, and a bunch of baseplates were sandbagged into place ahead of time, sure. That'd be entirely doable. Your idea of thin film deployment may be the best way to do this. The actual deployment of a thin film roll on a spindle attached to a tracked vehicle (for sufficient traction and torque for smooth deployment to avoid tearing) should be easier and less time consuming than emplacement and connection of hundreds of MegaFlex fans. Incidentally, this technology has also been produced in deployable fan format for satellites. However, deployment of a megawatt class array on the surface of Mars is another matter entirely.

I recently reviewed the thin film CIGS arrays Ascent Solar acquired from Vanguard Space Technologies when they acquired that company. The thin film arrays have been developed by Ascent Solar into mature technology and are in current use aboard aerospace vehicles for primary power. Upon further examination of how this could possibly be done, I think the thin film rollable / flexible arrays appear to be better suited for the type of deployment and output power required.

I was previously unaware, but apparently these thin film arrays produce substantially more output than the flexible fabric mounted hard cell arrays (UltraFlex / MegaFlex) during off-nominal irradiance (dawn and dusk). That means no complicated / expensive / heavy sun tracking mechanisms are required. These new CIGS arrays are printed in a continuous layering process to produce rolls of any length desired, UV resistant, long duration proven extreme temperature resistant (-256F to +374F), long duration proven rad-hardened (for more severe orbital environments), punctures or tears do not appreciably reduce the output (a function of the continuous layering / interconnection process), and they've even found a way to vary the voltage and amperage (critical to reduce losses and heating from high currents) within the same roll. Their highest voltage panel is 270V for electrically powered aerial drones, but their manufacturing equipment limits them to .3m times any length desired. Presumably, that could be scaled up. That said, it's the first true reel-to-reel printing process I'm aware of.

Since the US military is using their panels for portable power for soldiers, the cells have also been drop tested, shock tested, vibration tested, and corrosive environment tested and have passed MIL STD 810G. Critically, Ascent Solar receives funding from NASA JPL, USMC, USSOCOM, and FEMA. Orbital ATK obviously receives copious amounts of funding from NASA, DoD, and others, but I don't think Mr. Musk can afford them. Even Ascent Solar's space rated cells are ridiculously cheap compared to Orbital ATK's UltraFlex and MegaFlex technologies.

The most striking figures of merit are 1,125W/kg to 1,400W/kg for bare modules at 25C, but the more durable plastic encapsulated modules are 200W/kg. Plastic is heavy. Maybe some sort of clear graphene based coating would save weight. I'm going with 500W/kg for now. An electrically conductive coating of some kind is required to electrostatically clean the panels and static electricity is the only Mars proven method for solar panel cleaning, so that's what we're going with for now. A 1MW peak output plant requires 4,000kg of panels at 500W/kg.

This material will weigh less than 15kg per 100m^2 increment, so someone should figure out if the low dynamic pressure of the Martian surface winds are sufficient to lift the panel. Anyway, a company named Tethers Unlimited Inc has "Orb Weaver" and "Trusselator" robots that produce extremely strong (10kg per individual truss segment) and extremely lightweight (a child can easily lift a 10m truss structure with a single finger) composite trusses that can hold the panels and could potentially provide single axis Sun tracking mechanism to absolutely maximize power output. The Orb Weaver robot could potentially interconnect single panels to absolutely maximize the kW/kg of the panels. These are just ideas, but the concept of simply laying panels on the ground is not proper engineering.

Finally, this plant is going to be multiple square kilometers in size. That's not the sort of thing you put right next to the rocket that just landed, nor is it something you can pre-package. It'll have to be built on the surface and it'll take at least several months to do it. I have no idea what the PMAD for this device would weigh.

SpaceNut · 2018-05-30 19:21:26

All the hand waving for what a BFR is capable of is out as none of the falcon electronics will or can be used without lots of modification even with all the other developement its going to slide to the right for the launch to mars. Space x has a ton of work to do for the size of the life support as what they will have for the dragon will be no where large enough. Power for the BFR will also need to be developed as the panels will be huge and will be rotating for artificial gravity...not a good mix...

kbd512 · 2018-05-30 20:08:58

SpaceNut,

BFS can't do artificial gravity because it simply wasn't designed to do that. That's why I said a SEP-enabled cycler with a spinning habitable section is required. It's not possible to design a single ship that works well on Earth, in space, and on Mars using known technology. The design requirements are incompatible.

The only viable option I see to negate the requirement for artificial gravity is to use a superconducting magnetic sail, like the SharkFin Magnetic Sail that Craig Davidson proposed. It was based upon work done by Dr's Zubrin (electromagnetic sail), Jahonnen (electric sail), and Slough (plasma electromagnetic sail). If the transit time is a maximum of one week and you can go to Mars at any time that pleases you, versus every two years, then you don't need artificial gravity.

SpaceNut · 2018-05-30 20:44:01

Butt to Butt joined as if you are refueling for the artifical gravity since 2 ship are in transit otherwise there is no need for the bfr....

RobertDyck · 2018-05-31 01:39:13

kbd512 wrote:

SEP is Mandatory

Bull Shit! This is the forum of the Mars Society. If you don't like the Mars Society, then leave. If you want to be here, then read Robert Zubrin's book titled "The Case For Mars". I don't care which edition. Do I have to provide a link to Amazon?

kbd512 wrote:

Nobody, not even Elon Musk, can snap their fingers and create a Saturn V class multi-stage reusable rocket in two years.

In a TED Talks interview on YouTube, Gwynne Shotwell said BFR would fly within 10 years from now. Not 2022, a decade from now. This is me saying "Told you so."

louis · 2018-05-31 03:31:50

I was surprised to discover a couple of years back that Zubrin's book was out of print...but it was.

Times move on. A lot of what Zubrin had to say is still very relevant and interesting but it was almost another age back then and the idea of sending a super rocket like the BFR to land on Mars was not really on the agenda at the time.

The reference in the video to "within a decade" relates to Earth-to-Earth BFR transit. You would have to build the spaceport infrastructure to support Earth-to-Earth transit and navigate a variety of planning and safety assessment processes, so clearly that would add years to the project. I didn't hear her say building the BFR would take 10 years. If she did, I'd be interested for you to give a time on the video where she said it.

RobertDyck wrote:

kbd512 wrote:
SEP is Mandatory
Bull Shit! This is the forum of the Mars Society. If you don't like the Mars Society, then leave. If you want to be here, then read Robert Zubrin's book titled "The Case For Mars". I don't care which edition. Do I have to provide a link to Amazon?
kbd512 wrote:
Nobody, not even Elon Musk, can snap their fingers and create a Saturn V class multi-stage reusable rocket in two years.
In a TED Talks interview on YouTube, Gwynne Shotwell said BFR would fly within 10 years from now. Not 2022, a decade from now. This is me saying "Told you so."

louis · 2018-05-31 04:38:16

kbd512 wrote:

Louis,
SEP is Mandatory
If launch and maintenance costs and total tonnage delivered are a consideration at all, then yes, SEP is necessary for Mars settlement. It's not a requirement for the first few missions, but a sustainable colonization architecture is required and as cheap as the fuel might be, maintenance is definitely not cheap. The more flights that deliver useful payload versus fuel to go anywhere to do anything, the lower the cost of transport becomes and the more people who can afford to go live on Mars. $250K vs $50K. At $50K virtually anyone in the western world and an increasing number of people in the eastern world can afford to go to Mars. At $50K per person, a corporation can afford to send their scientists to Mars to do research and development projects to improve things like food production, solar panels, batteries, you name it.

The BFR can deliver 150 tonnes to Mars. That's a huge tonnage. With economies of scale and rocket reuse we could be looking at getting the per kg figure down below $500 per kg. I think you can undertake profitable trade with Earth at that sort of cost level.

Also, it appears as though Space X think they can get the BFR flight time down to 3-4 months...although I've not been able to bottom that out. If that is the case, then the argument for AG in flight becomes less compelling as well.

So, an SEP while it will probably be adopted eventually is not necessary for a major colonisation effort.

kbd512 wrote:

SpaceX's Big Rockets and Past Performance
When was the last time you saw a Space Shuttle larger than the orbiter's main tank fly without issue? Since both the Boeing 747 flew and the Airbus A380 flew, that should mean StratoLaunch's Roc can just make sure the engines have gas and then takeoff, right? Falcon Heavy flew six years after Mr. Musk thought it would. Nobody, not even Elon Musk, can snap their fingers and create a Saturn V class multi-stage reusable rocket in two years. That simply will not happen and anyone who is not being incredibly naive should already know that. Four to six years is far more probable and in line with past performance.

NASA went from proposal to completion in 5 years on Saturn V and that was with 1960s technology - no Computer Aided Design and no 3D printing for instance.

A lot of the development work on BFR has already been done. The ITS design, precursor of the BFR, dates from at least 2016. Even before the BFR was announced, work on the engines and propellant tank was well advanced. So I think this is a comparable timeframe, it's just that Space X have the advantage over 1960s NASA of (a) using 21st century design and test technology and (b) being able to build on 70 years' knowledge of how to build big human passenger rockets. In addition, much of the knowledge gained in developing the Falcon series to date can be applied to the BFR.

kbd512 wrote:

Multi-Megawatt Class PV Farms on Mars
I think "pre-cabled up" solar arrays are a really bad idea. The deployment area may not lend itself to that sort of pre-packaged solution. If the ground was graded, leveled, and a bunch of baseplates were sandbagged into place ahead of time, sure. That'd be entirely doable. Your idea of thin film deployment may be the best way to do this. The actual deployment of a thin film roll on a spindle attached to a tracked vehicle (for sufficient traction and torque for smooth deployment to avoid tearing) should be easier and less time consuming than emplacement and connection of hundreds of MegaFlex fans. Incidentally, this technology has also been produced in deployable fan format for satellites. However, deployment of a megawatt class array on the surface of Mars is another matter entirely.
I recently reviewed the thin film CIGS arrays Ascent Solar acquired from Vanguard Space Technologies when they acquired that company. The thin film arrays have been developed by Ascent Solar into mature technology and are in current use aboard aerospace vehicles for primary power. Upon further examination of how this could possibly be done, I think the thin film rollable / flexible arrays appear to be better suited for the type of deployment and output power required.
I was previously unaware, but apparently these thin film arrays produce substantially more output than the flexible fabric mounted hard cell arrays (UltraFlex / MegaFlex) during off-nominal irradiance (dawn and dusk). That means no complicated / expensive / heavy sun tracking mechanisms are required. These new CIGS arrays are printed in a continuous layering process to produce rolls of any length desired, UV resistant, long duration proven extreme temperature resistant (-256F to +374F), long duration proven rad-hardened (for more severe orbital environments), punctures or tears do not appreciably reduce the output (a function of the continuous layering / interconnection process), and they've even found a way to vary the voltage and amperage (critical to reduce losses and heating from high currents) within the same roll. Their highest voltage panel is 270V for electrically powered aerial drones, but their manufacturing equipment limits them to .3m times any length desired. Presumably, that could be scaled up. That said, it's the first true reel-to-reel printing process I'm aware of.
Since the US military is using their panels for portable power for soldiers, the cells have also been drop tested, shock tested, vibration tested, and corrosive environment tested and have passed MIL STD 810G. Critically, Ascent Solar receives funding from NASA JPL, USMC, USSOCOM, and FEMA. Orbital ATK obviously receives copious amounts of funding from NASA, DoD, and others, but I don't think Mr. Musk can afford them. Even Ascent Solar's space rated cells are ridiculously cheap compared to Orbital ATK's UltraFlex and MegaFlex technologies.
The most striking figures of merit are 1,125W/kg to 1,400W/kg for bare modules at 25C, but the more durable plastic encapsulated modules are 200W/kg. Plastic is heavy. Maybe some sort of clear graphene based coating would save weight. I'm going with 500W/kg for now. An electrically conductive coating of some kind is required to electrostatically clean the panels and static electricity is the only Mars proven method for solar panel cleaning, so that's what we're going with for now. A 1MW peak output plant requires 4,000kg of panels at 500W/kg.
This material will weigh less than 15kg per 100m^2 increment, so someone should figure out if the low dynamic pressure of the Martian surface winds are sufficient to lift the panel. Anyway, a company named Tethers Unlimited Inc has "Orb Weaver" and "Trusselator" robots that produce extremely strong (10kg per individual truss segment) and extremely lightweight (a child can easily lift a 10m truss structure with a single finger) composite trusses that can hold the panels and could potentially provide single axis Sun tracking mechanism to absolutely maximize power output. The Orb Weaver robot could potentially interconnect single panels to absolutely maximize the kW/kg of the panels. These are just ideas, but the concept of simply laying panels on the ground is not proper engineering.
Finally, this plant is going to be multiple square kilometers in size. That's not the sort of thing you put right next to the rocket that just landed, nor is it something you can pre-package. It'll have to be built on the surface and it'll take at least several months to do it. I have no idea what the PMAD for this device would weigh.

Ascent Solar sounds like it could well be the solution needed for generating sufficient solar power on Mars. Very interested to read about that.

But I am struggling to see how the PV plant could be "multiple square kilometres".

Using this guide from Ascent Solar:

http://www.ascentsolar.com/superlight-technology.html

A 100 x 100 metre facility (10,000 sq metres) would weigh 4000 kgs and produce peak 800 Kws. Taking a quarter of that output for Mars surface PV system would give you a peak production figure of 200 Kws. We don't really have accurate figures for propellant prodcution power take, but it would take place over probably about 600 sols. I would guess something like 0.08 sq. km i.e. 1.6 MWs peak would suffice (allowing then for battery storage or other storage systems, to provide a steady power supply of at least 250 Kws throughout the day). Even if you add in a safety margin for dust storms, and you then quadruple that again, you are still only at 0.32 sq. kms. All told the mass would be 130 tonnes and I tend to add on a third for PMAD = 175 tonnes. But this may be a gross estimate if the power take of the propellant production plant is much lower than expected.

I don't see why robot rovers can't lay out the flexible PV at a fast rate. The processes involved would be removal of boulders by small bulldozer rovers, unrolling, fixing on to taut lines with placement of interval supports. There would be a variety of angles to provide as even as possible power supply through the sol. Maybe 2 sols to lay out 0.1 sq km. 64 sols for a major 0.32 sq. km. facility.

louis · 2018-05-31 04:55:23

I've seen journey times of 3-4 months quoted for the BFR. There does seem to be some spare fuel capacity...If the journey time is under 4 months, I doubt AG is really even desirable.

kbd512 wrote:

SpaceNut,
BFS can't do artificial gravity because it simply wasn't designed to do that. That's why I said a SEP-enabled cycler with a spinning habitable section is required. It's not possible to design a single ship that works well on Earth, in space, and on Mars using known technology. The design requirements are incompatible.
The only viable option I see to negate the requirement for artificial gravity is to use a superconducting magnetic sail, like the SharkFin Magnetic Sail that Craig Davidson proposed. It was based upon work done by Dr's Zubrin (electromagnetic sail), Jahonnen (electric sail), and Slough (plasma electromagnetic sail). If the transit time is a maximum of one week and you can go to Mars at any time that pleases you, versus every two years, then you don't need artificial gravity.

Terraformer · 2018-05-31 06:44:46

louis wrote:

The BFR can is intended to deliver 150 tonnes to Mars.

There, fixed it for you.

How much would an SEP demonstration mission cost? I mean, one powerful (and cheap - no using xenon) enough to use for human missions, or at least mass cargo transport. A 1 tonne spacecraft, perhaps, done on a budget of a couple hundred million dollars as part of the discovery program? Send it

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