Solar plus turbine...

louis · 2017-06-03 12:10:34

There is no "massive infrastructure" requirement. The nuclear option as described by kbd (10 x 10 Kwe KiloPower reactors) is clocking in at
a minimum of 15 tonnes, and that's without any batteries, or additional PV.

The solar power system would amount to about 13 tonnes, and remember a lot of the battery mass is doubling up in any case (it can be used to power Rovers when conditions are normal but be used as back up when required.

Oldfart1939 wrote:

Louis-
Your dedication to the concept of Solar-only on Mars is commendable, but in my opinion--misguided. I envision a combination of nuclear , supplemented by Solar. The massive infrastructure requirement you propose is NOT GOING TO HAPPEN! A small nuclear reactor, as in the original Mars Direct proposal will lead the way, and solar backup will be available some 40% of the time. The reality is food and research equipment will compose a large portion of the early mass landed on the surface, not batteries and other equipment for manufacture of solar panels, turbines, and excess methane or Oxygen to power the colony. Everything you suggest always involves massive infrastructure investments.

SpaceNut · 2017-06-03 13:47:09

The "massive infrastructure investments" can be done via slow build up of an extra cargo lander per mission to support growing the inital site into that of a permanent base. So by planning the pieces and the mass of them we will bring forward something other than a temporary science site with each mission and bring around permanent science as the end goal.

The extra cargo landers as well can come from recycling the empty units once refilled with fuel back to orbit to be restocked at earth orbit once brought back. Depending on the lander design it might be retrofitted with a heat shield for earth entry with cargo from mars as well.

kbd512 · 2017-06-03 14:25:49

louis wrote:

You mean a base load requirement for life support? I don't accept the life support requirement is necessarily constant at all. To take oxygen for example, I think we will probably make that in loads, to ensure we have an ongoing emergency surplus and we will be using it for other purposes, as well in any case. In terms of heat, well yes you can have a constant, but on Earth that is rare - it is more normal to heat your water that is then stored in a lagged container and heating is normally thermostatically controlled so it goes on and off. Fresh water can be produced at any time of day. There is probably a very small baseload requirement for fans, venting and so on but that will easily be covered by batteries.

Ok, well, you don't think it's constant. There's a reason the equipment is constantly "on" (consuming electrical power).

louis wrote:

I wasn't aware that the reactors were capable of produce more than their rated capacity e.g. 10Kwe for a KiloPower unit. Are you saying they can? Do you have any link to back that up?

I never claimed that the reactor could produce more than its rated output. I said the output can be varied, as in 1kWe to 10kWe, in order to extend the operational life of the reactor and to match the demand instead of dumping kilowatts of electrical power into a grounding rod. The reactor has a control rod for neutron moderation and because the volume to surface area ratio is so small, inserting the control rod is about as close to flipping a switch as is possible. Neutron moderation is an essential part of how fission is started / stopped / moderated in any reactor.

louis wrote:

I very much doubt it will be NASA who get humans to Mars. The jury is still out on the weight of panels that will be used on Mars but (a) tecnological progress is being made towards panels that are durable (UV protected), lightweight and flexible. My view is there will probably be a mix. However it all depends on technical developments. The weather on Mars is at least benign - no hurricanes, no rain, no snow, no floods and there are no herds of animals to go trampling over your panels either.

Exactly zero people have landed on the moon in the near half century since NASA did it. I very much doubt you'll see anyone get people to and from Mars, alive, until NASA does it.

The jury isn't out on the weight of Orbital ATK's panels. Those are the only panels that have ever been sent to Mars by the US, and with good reason. They work. That said, continuous output requirements for these robotic missions have been minimal. Even then, the landers and rovers lose power. That's unacceptable for a mission involving humans.

louis wrote:

NASA are working on roll out flexible ultra lightweight PV panelling.

Great. They absolutely should be working on better solar panels.

louis wrote:

It appears you have no link to the 99% irradiance drop claim (beyond asking me to google a book). Under a solar energy system, there will be plenty of back up in the form of methane/oxygen. I have never seen any evidence of a dust storm causing more than a 90% drop in insolation on the surface (and even then only for a few days IIRC). With a system that delivers 2450 KWhes in normal weather conditions, that will mean you have a minimum of 245 KWhes available even in those extreme conditions, without back-up.

I should have said 99% of direct sunlight was blocked by the dust storms. It's in a NASA press release from 2007. If you want the original, you can request it from NASA. The same phenomenon was experienced by the Viking landers. It just happens and there's no sense in ignoring it or pretending it won't happen.

If there's a 90% drop in insolation for a month, what's your backup plan?

Here's a rehash from Planetary.org's website:

Mars Exploration Rovers Update: Opportunity and Spirit Brave Global Dust Storm

The same information can be found on Wikipedia.

louis wrote:

When someone asks for a citation for a claimed figure, they don't normally expect to be given generalised links, and asked to do their own research, wading through pages and pages of presentations...

In the document linked below, Page 5, Table 1, entitled "Kilopower System Options" lists the total mass of a 10kWe Kilopower system as 1544kg. That is the complete mass of the 10kWe Kilopower fission reactor.

Development of NASA’s Small Fission Power System for Science and Human Exploration

louis wrote:

Well if it is a "little" high as you know seem to accept it affects the comparison of course.
I don't accept your figure of nearly 106 tonnes for a solar energy system. It's patently absurd.

It's patently mathematical, Louis. A requirement for continuous (the opposite of intermittent or variable) power, is exactly like the requirement to pay money owed to the mob. The only difference is that instead of "F you, pay me", it's "F you, power me". If solar was more energy dense than nuclear and you came here espousing the merits of nuclear power, I would make the exact same arguments about mass. The world works the way it works, not the way you or I want it to work.

The larger figures were for the 100kWe continuous electrical power system. If insolation is only 36.5% of what it normally is, and it will be as part of the normal insolation cycle, you still have to produce the power. Mars is 50% further from the Sun than Earth is to start with, it has a day/night cycle just like Earth, and it has weather events that all but block all direct sunlight. Fission reactors are unaffected by insolation.

louis wrote:

I need to go over the figures again, but I think probably 5 tonnes for the panels, using current technology, 1.6 tonnes for associated electrical equipment, 2 tonnes for batteries (doubling up on use, as Rover and other batteries), maybe 1.5 tonnes for a methane/oxygen plant, 2.5 tonnes for gas storage and 500 kgs for two 20 Kw generators. Around 13 tonnes in total out of budget of perhaps 70 tonnes.
Of course if we see ultra lightweight UV resistant PV panelling emerge, the total will be substantially less. Likewise with improved battery storage. Likewise if we can find a way of storing methane and oxygen in a less mass intensive way. That's quite possible as well. THere are lightweight storage solutions.
So with a solar energy system, it's basically a balancing act between PV panels, batteries,generators, and methane storage. We might also have a solar reflector system added to the overall mix.

How much continuous electrical power is this system capable of producing?

Tell me what the backup plan is if you experience a massive drop in PV panel output for a month due to a dust storm.

Where is the Hydrogen to produce methane coming from?

13t is enough mass for eight (13,000 / 1,545 = 8.4) of the 10kWe Kilopower units that can provide 80kWe continuously.

There is no methalox plant in development and there probably will never be one that actually works if you attempt to power it with solar panels, as a function of the mass required to produce continuous output. That's one application that has a high continuous power output requirement that solar panels and batteries can't provide for comparable mass, with respect to a fission reactor.

louis wrote:

As indicated before, I don't think NASA will get humans to Mars. It will be Space X. As far as I know, they haven't specified their early energy system yet.

SpaceX has yet to put a human in space and the only reason it's made it this far is funding from NASA. We're a ways away from a Mars mission with humans. SpaceX doesn't have a vehicle that can take 1 person to Mars. They have a rocket and a family of capsule systems. Nobody has reliable, long duration life support systems. NASA is still working on that.

louis wrote:

I don't think you've established a nuclear solution would have the lower mass (especially if you are going to take some batteries - are you?). You invented a crazy figure for solar and then compared it with a "nuclear only" option.

I told you what Kilopower weighs and I told you what the mass of the PV panels and batteries would be if the continuous power requirement is only 10kWe. My quoted figures are pretty accurate because they use the manufacturers' own product literature and the manufacturers' claims are backed with actual performance data that NASA has collected. I ignored the dust storms, but any mission involving humans that is not a suicide mission can't.

If you think less PV panel power is required or less battery power is required than what I posted, then demonstrate how you arrived at your figures. That's exactly what I did. Any argument based on personal belief instead of mathematics is not a reality-based argument.

Approximately 2.74 times (SpaceNut says 3 times) as much PV panel surface area is required on the surface of Mars as compared to low Earth orbit, as a function of the solar insolation received on the surface of Mars, to produce the same output as PV panels in low Earth orbit. We have pretty accurate maps, numbers, and equations for that information now because we have solar-powered vehicles on the surface of Mars and solar-powered satellites in orbit around Mars with measurement equipment and data from our spacecraft.

louis wrote:

I am not engaging in magical thinking.

Post your mass figures and the calculations you made to arrive at those figures. I've seen a lot of "I think" and "I believe" statements in what you've stated and not much in the way of computation. Until you do that, then like GW says, we're arguing about the number of angels on the head of a pin.

louis · 2017-06-03 18:25:08

I'd accept there is a v. minimal constant base load requirement for life support, but most of the "heavy lifting" (oxygen production, water processing, heating etc) does not have to be powered at a constant rate.

So you are accepting that with your ten 10Kwe nuclear units you cannot produce more than 100 Kwe at any point during the day?

You'll see from another thread that the science shows surface insolation levels don't drop more than about two thirds even during the most intense dust storms. Obviously with Mars Rovers, there is no one around to ensure that the solar panels are cleaned and in any case the robots often have to shut down to protect their mechanics. I think it is inconceivable will deliver less than 10% of normal power in a dust storm. V. unlikely to drop below 20% I would say.

I will provide some more detailed calculations shortly in a separate thread.

I think something around 13 tonnes based on PV is v. doable. My outline is based on research, not just pulling figures out of thin air.

kbd512 wrote:

louis wrote:
You mean a base load requirement for life support? I don't accept the life support requirement is necessarily constant at all. To take oxygen for example, I think we will probably make that in loads, to ensure we have an ongoing emergency surplus and we will be using it for other purposes, as well in any case. In terms of heat, well yes you can have a constant, but on Earth that is rare - it is more normal to heat your water that is then stored in a lagged container and heating is normally thermostatically controlled so it goes on and off. Fresh water can be produced at any time of day. There is probably a very small baseload requirement for fans, venting and so on but that will easily be covered by batteries.
Ok, well, you don't think it's constant. There's a reason the equipment is constantly "on" (consuming electrical power).
louis wrote:
I wasn't aware that the reactors were capable of produce more than their rated capacity e.g. 10Kwe for a KiloPower unit. Are you saying they can? Do you have any link to back that up?
I never claimed that the reactor could produce more than its rated output. I said the output can be varied, as in 1kWe to 10kWe, in order to extend the operational life of the reactor and to match the demand instead of dumping kilowatts of electrical power into a grounding rod. The reactor has a control rod for neutron moderation and because the volume to surface area ratio is so small, inserting the control rod is about as close to flipping a switch as is possible. Neutron moderation is an essential part of how fission is started / stopped / moderated in any reactor.
louis wrote:
I very much doubt it will be NASA who get humans to Mars. The jury is still out on the weight of panels that will be used on Mars but (a) tecnological progress is being made towards panels that are durable (UV protected), lightweight and flexible. My view is there will probably be a mix. However it all depends on technical developments. The weather on Mars is at least benign - no hurricanes, no rain, no snow, no floods and there are no herds of animals to go trampling over your panels either.
Exactly zero people have landed on the moon in the near half century since NASA did it. I very much doubt you'll see anyone get people to and from Mars, alive, until NASA does it.
The jury isn't out on the weight of Orbital ATK's panels. Those are the only panels that have ever been sent to Mars by the US, and with good reason. They work. That said, continuous output requirements for these robotic missions have been minimal. Even then, the landers and rovers lose power. That's unacceptable for a mission involving humans.
louis wrote:
NASA are working on roll out flexible ultra lightweight PV panelling.
Great. They absolutely should be working on better solar panels.
louis wrote:
It appears you have no link to the 99% irradiance drop claim (beyond asking me to google a book). Under a solar energy system, there will be plenty of back up in the form of methane/oxygen. I have never seen any evidence of a dust storm causing more than a 90% drop in insolation on the surface (and even then only for a few days IIRC). With a system that delivers 2450 KWhes in normal weather conditions, that will mean you have a minimum of 245 KWhes available even in those extreme conditions, without back-up.
I should have said 99% of direct sunlight was blocked by the dust storms. It's in a NASA press release from 2007. If you want the original, you can request it from NASA. The same phenomenon was experienced by the Viking landers. It just happens and there's no sense in ignoring it or pretending it won't happen.
If there's a 90% drop in insolation for a month, what's your backup plan?
Here's a rehash from Planetary.org's website:
Mars Exploration Rovers Update: Opportunity and Spirit Brave Global Dust Storm
The same information can be found on Wikipedia.
louis wrote:
When someone asks for a citation for a claimed figure, they don't normally expect to be given generalised links, and asked to do their own research, wading through pages and pages of presentations...
In the document linked below, Page 5, Table 1, entitled "Kilopower System Options" lists the total mass of a 10kWe Kilopower system as 1544kg. That is the complete mass of the 10kWe Kilopower fission reactor.
Development of NASA’s Small Fission Power System for Science and Human Exploration
louis wrote:
Well if it is a "little" high as you know seem to accept it affects the comparison of course.
I don't accept your figure of nearly 106 tonnes for a solar energy system. It's patently absurd.
It's patently mathematical, Louis. A requirement for continuous (the opposite of intermittent or variable) power, is exactly like the requirement to pay money owed to the mob. The only difference is that instead of "F you, pay me", it's "F you, power me". If solar was more energy dense than nuclear and you came here espousing the merits of nuclear power, I would make the exact same arguments about mass. The world works the way it works, not the way you or I want it to work.
The larger figures were for the 100kWe continuous electrical power system. If insolation is only 36.5% of what it normally is, and it will be as part of the normal insolation cycle, you still have to produce the power. Mars is 50% further from the Sun than Earth is to start with, it has a day/night cycle just like Earth, and it has weather events that all but block all direct sunlight. Fission reactors are unaffected by insolation.
louis wrote:
I need to go over the figures again, but I think probably 5 tonnes for the panels, using current technology, 1.6 tonnes for associated electrical equipment, 2 tonnes for batteries (doubling up on use, as Rover and other batteries), maybe 1.5 tonnes for a methane/oxygen plant, 2.5 tonnes for gas storage and 500 kgs for two 20 Kw generators. Around 13 tonnes in total out of budget of perhaps 70 tonnes.
Of course if we see ultra lightweight UV resistant PV panelling emerge, the total will be substantially less. Likewise with improved battery storage. Likewise if we can find a way of storing methane and oxygen in a less mass intensive way. That's quite possible as well. THere are lightweight storage solutions.
So with a solar energy system, it's basically a balancing act between PV panels, batteries,generators, and methane storage. We might also have a solar reflector system added to the overall mix.
How much continuous electrical power is this system capable of producing?
Tell me what the backup plan is if you experience a massive drop in PV panel output for a month due to a dust storm.
Where is the Hydrogen to produce methane coming from?
13t is enough mass for eight (13,000 / 1,545 = 8.4) of the 10kWe Kilopower units that can provide 80kWe continuously.
There is no methalox plant in development and there probably will never be one that actually works if you attempt to power it with solar panels, as a function of the mass required to produce continuous output. That's one application that has a high continuous power output requirement that solar panels and batteries can't provide for comparable mass, with respect to a fission reactor.
louis wrote:
As indicated before, I don't think NASA will get humans to Mars. It will be Space X. As far as I know, they haven't specified their early energy system yet.
SpaceX has yet to put a human in space and the only reason it's made it this far is funding from NASA. We're a ways away from a Mars mission with humans. SpaceX doesn't have a vehicle that can take 1 person to Mars. They have a rocket and a family of capsule systems. Nobody has reliable, long duration life support systems. NASA is still working on that.
louis wrote:
I don't think you've established a nuclear solution would have the lower mass (especially if you are going to take some batteries - are you?). You invented a crazy figure for solar and then compared it with a "nuclear only" option.
I told you what Kilopower weighs and I told you what the mass of the PV panels and batteries would be if the continuous power requirement is only 10kWe. My quoted figures are pretty accurate because they use the manufacturers' own product literature and the manufacturers' claims are backed with actual performance data that NASA has collected. I ignored the dust storms, but any mission involving humans that is not a suicide mission can't.
If you think less PV panel power is required or less battery power is required than what I posted, then demonstrate how you arrived at your figures. That's exactly what I did. Any argument based on personal belief instead of mathematics is not a reality-based argument.
Approximately 2.74 times (SpaceNut says 3 times) as much PV panel surface area is required on the surface of Mars as compared to low Earth orbit, as a function of the solar insolation received on the surface of Mars, to produce the same output as PV panels in low Earth orbit. We have pretty accurate maps, numbers, and equations for that information now because we have solar-powered vehicles on the surface of Mars and solar-powered satellites in orbit around Mars with measurement equipment and data from our spacecraft.
louis wrote:
I am not engaging in magical thinking.
Post your mass figures and the calculations you made to arrive at those figures. I've seen a lot of "I think" and "I believe" statements in what you've stated and not much in the way of computation. Until you do that, then like GW says, we're arguing about the number of angels on the head of a pin.

Antius · 2017-06-04 08:42:10

Control rods do not moderate neutrons, they absorb them. All of the space reactor concepts I have seen have been fast reactors, either sodium or lithium cooled.

Solar power does not work well either as a mission power source or a permanent base power source on Mars. As a mission power source, even when stretched to its maximum feasible limits it does not compete with a small fast reactor on a weight basis, even at the most favourable location on Mars. And it takes hundreds of EVA hours to set up. As a base power source, it does not perform well on a mass basis and requires demand side management to work without infeasible levels of storage. Making solar power systems on Mars is not energetically favourable, as energy payback times are at least 1 decade.

Louis has an ideological obsession with solar power. That is why these debates appear to go nowhere. It isn't about the technology or real world practicality, it is about his emotions. We have done enough analysis now to show that this is not a good solution for any stage of the Mars campaign. If one man cannot accept that for personal reasons, so be it. The rest of you should get on with developing practical plans.

Last edited by Antius (2017-06-04 08:43:00)

Oldfart1939 · 2017-06-04 13:22:50

Antius-

Thank you for stating bluntly what many of us were thinking. Let's get "Our Asses to Mars!"

louis · 2017-06-04 15:37:57

I think we should do each other the courtesy of accepting we are all setting out what we consider best for Mars settlement. I am not sure why you can't extend me that simple courtesy.

Kbd's proposal is not yours. Kbd proposes 10 x 10 Kw KiloPower units at over 1500 kgs a time, so it's 15 tonnes. A solar energy system would come nowhere near that.

Trying to shut down the debate when you can see it is not going your way is not the mark of a rational approach.

I will be setting out my approach in due course.

You now seem to be trying to load the dice by referring to a (singular) fast reactor. What - no batteries? No back up? All you have got is a static mission on a knife edge, dependent on that one reactor not failing them.

Antius wrote:

Control rods do not moderate neutrons, they absorb them. All of the space reactor concepts I have seen have been fast reactors, either sodium or lithium cooled.
Solar power does not work well either as a mission power source or a permanent base power source on Mars. As a mission power source, even when stretched to its maximum feasible limits it does not compete with a small fast reactor on a weight basis, even at the most favourable location on Mars. And it takes hundreds of EVA hours to set up. As a base power source, it does not perform well on a mass basis and requires demand side management to work without infeasible levels of storage. Making solar power systems on Mars is not energetically favourable, as energy payback times are at least 1 decade.
Louis has an ideological obsession with solar power. That is why these debates appear to go nowhere. It isn't about the technology or real world practicality, it is about his emotions. We have done enough analysis now to show that this is not a good solution for any stage of the Mars campaign. If one man cannot accept that for personal reasons, so be it. The rest of you should get on with developing practical plans.

SpaceNut · 2017-06-04 16:43:48

ATK Solar arrays: https://www.nasa.gov/offices/oct/home/feature_sas.html

UltraFlex™ Solar Array Systems

http://www.spaceflightinsider.com/missi … ht-lander/

MegaFlex™ Solar Array

ATK's 9.6 meter (32 ft) diameter Solar Electric Propulsion (SEP) MegaFlex solar array design is capable of generating approximately 40kW of power with two wings.

7.5 square meters for 20kW or 2.74 m x 2.74 m size this is the on orbit wattage for 1100 w approximate for each meter to which that makes them near 40% efficient....

Edit: Correction due to the wedges not being totally populated with cells the Square meters will drop to 7 m^2 with the efficiency dropping to 35% which would make these the Spectra tripple layer solar cells that Rob has posted about before.

louis · 2017-06-04 18:01:45

40% is good!

SpaceNut wrote:

ATK Solar arrays: https://www.nasa.gov/offices/oct/home/feature_sas.html
UltraFlex™ Solar Array Systems
http://www.spaceflightinsider.com/missi … ht-lander/
MegaFlex™ Solar Array
ATK's 9.6 meter (32 ft) diameter Solar Electric Propulsion (SEP) MegaFlex solar array design is capable of generating approximately 40kW of power with two wings.
7.5 square meters for 20kW or 2.74 m x 2.74 m size this is the on orbit wattage for 1100 w approximate for each meter to which that makes them near 40% efficient....
Edit: Correction due to the wedges not being totally populated with cells the Square meters will drop to 7 m^2 with the efficiency dropping to 35% which would make these the Spectra tripple layer solar cells that Rob has posted about before.

Oldfart1939 · 2017-06-04 18:42:46

Louis--

Not at all. I have repeatedly stated the SAFE-400 is absolutely THE way to utilize nuclear power on Mars, and the core weighs in at less that 1000 kg. I'm a staunch supporter of Dr. Zubrin and locating the reactor in either a crater or burying the item under regolith. Even if we heavily shield the reactor, it will be far less than the solar array you are promoting. I have not decried use of solar power for several other applications, but I would simply refuse to go if there were not 2 independent forms of energy available. And no, I don't mean a combustion of methane and oxygen as a backup. Too many mechanical issues that could, and probably WOULD arise.
Not wishing to be rude, but I've become simply tired of examining the same concept in many different guises--time after time after time. The numbers just don't change.

louis · 2017-06-04 18:52:28

The numbers do change. Kbd, who supports nuclear, is quoting 250 W per Kg for solar panel and SpaceNut supports that figure.

Giving a figure for the nuclear core of a reactor is absolutely meaningless. We need a total mass figure. Sounds like you are another "soloist" when it comes to nuclear - you are just going to have a single nuclear reactor? Wow, I admire your bravery on behalf of the poor crew who are going to front up your bravery. What if it doesn't work for some reason? You appear to be claiming that something as well established as a methane generator can go wrong but a nuclear reactor/generator cannot go wrong...

Oldfart1939 wrote:

Louis--
Not at all. I have repeatedly stated the SAFE-400 is absolutely THE way to utilize nuclear power on Mars, and the core weighs in at less that 1000 kg. I'm a staunch supporter of Dr. Zubrin and locating the reactor in either a crater or burying the item under regolith. Even if we heavily shield the reactor, it will be far less than the solar array you are promoting. I have not decried use of solar power for several other applications, but I would simply refuse to go if there were not 2 independent forms of energy available. And no, I don't mean a combustion of methane and oxygen as a backup. Too many mechanical issues that could, and probably WOULD arise.
Not wishing to be rude, but I've become simply tired of examining the same concept in many different guises--time after time after time. The numbers just don't change.

kbd512 · 2017-06-04 19:11:25

louis wrote:

I think we should do each other the courtesy of accepting we are all setting out what we consider best for Mars settlement. I am not sure why you can't extend me that simple courtesy.

My commentary has been directed towards what's required for Mars surface exploration. There won't be any colonization until we know where the water is.

louis wrote:

Kbd's proposal is not yours. Kbd proposes 10 x 10 Kw KiloPower units at over 1500 kgs a time, so it's 15 tonnes. A solar energy system would come nowhere near that.

I proposed sending a pair of Kilopower units to Mars and skipping methalox production for exploration missions. There's no need to send ten reactor units for an exploration mission if you delay all the energy-intensive ISRU experiments until after we've confirmed the locations of planetary resources with ground exploration teams. Exploration missions should use NTO/MMH propellants for ascent vehicles and kick stages. Long duration cryogen storage is not a technology to test during surface exploration missions.

louis wrote:

Trying to shut down the debate when you can see it is not going your way is not the mark of a rational approach.

Nobody here is de-justifying use of PV power, Louis. PV power will be present for every mission to provide power in space where both energy density and power density achievable are higher for PV panels than fission reactors until the continuous power requirement is 1MWe or more when the mission is 1.5AU or closer to the Sun.

Why do you expect people to automatically agree with you when you make claims about technologies like portable robotic methalox plants that don't exist or make claims about electrical power demand that don't accurately portray how ISS uses electrical power, never mind an outpost on another planet with a day/night cycle that's 50% further from the Sun than ISS is?

louis wrote:

I will be setting out my approach in due course.

Will your approach use technologies like MegaFlex and Kilopower that are in active development by NASA's contractors or technologies that likely won't be qualified for space flight for another decade or so?

louis wrote:

You now seem to be trying to load the dice by referring to a (singular) fast reactor. What - no batteries? No back up? All you have got is a static mission on a knife edge, dependent on that one reactor not failing them.

I proposed sending a pair of Kilopower reactors to the surface. The pair of fission reactors provide redundancy. I also proposed sending a small tracked vehicle equipped with a permanent battery and homopolar generator. That vehicle will also be capable of providing continuous electrical power for the astronauts. It'll provide more continuous power than both reactors with far less mass than solar or nuclear. I want to land everything with HIAD and AF-M315E monopropellant. All mission component masses are around 5t, except the ascent stage. If micro capsules are developed to hold one or two astronauts, then the ascent stages can mass around 5t, too.

The technologies I favor to provide electrical power for mobile surface exploration vs bases vs colonies all vary because some technologies are more suitable than others for specific use cases.

louis · 2017-06-04 19:40:18

The water is virtually everywhere! At Chryse Planitia, my favoured landing zone, it's about 6% of the regolith. You just take a 100 Kg of regolith, heat it up and you have 6 kgs of water. It couldn't be more simple!

Are you suggesting 2 x 10 Kw nuclear units? What if one fails? You are down to 10 Kw constant?

You have a particular vision of nuclear power that may incorporate PV (though I don't recall you mentioning what tonnage) but others do not.

You talk about me referencing plants that don't exist while you and others reference KiloPower and SAFE 400 units that also don't exist!

Well as you said to me, I suggest you lay out in detail your mission proposal as reagards energy with detailed mass calculations. Then we can examine exactly what is you are putting forward. On the face of it, though, 20 Kwes constant doesn't sound good enough.

kbd512 wrote:

louis wrote:
I think we should do each other the courtesy of accepting we are all setting out what we consider best for Mars settlement. I am not sure why you can't extend me that simple courtesy.
My commentary has been directed towards what's required for Mars surface exploration. There won't be any colonization until we know where the water is.
louis wrote:
Kbd's proposal is not yours. Kbd proposes 10 x 10 Kw KiloPower units at over 1500 kgs a time, so it's 15 tonnes. A solar energy system would come nowhere near that.
I proposed sending a pair of Kilopower units to Mars and skipping methalox production for exploration missions. There's no need to send ten reactor units for an exploration mission if you delay all the energy-intensive ISRU experiments until after we've confirmed the locations of planetary resources with ground exploration teams. Exploration missions should use NTO/MMH propellants for ascent vehicles and kick stages. Long duration cryogen storage is not a technology to test during surface exploration missions.
louis wrote:
Trying to shut down the debate when you can see it is not going your way is not the mark of a rational approach.
Nobody here is de-justifying use of PV power, Louis. PV power will be present for every mission to provide power in space where both energy density and power density achievable are higher for PV panels than fission reactors until the continuous power requirement is 1MWe or more when the mission is 1.5AU or closer to the Sun.
Why do you expect people to automatically agree with you when you make claims about technologies like portable robotic methalox plants that don't exist or make claims about electrical power demand that don't accurately portray how ISS uses electrical power, never mind an outpost on another planet with a day/night cycle that's 50% further from the Sun than ISS is?
louis wrote:
I will be setting out my approach in due course.
Will your approach use technologies like MegaFlex and Kilopower that are in active development by NASA's contractors or technologies that likely won't be qualified for space flight for another decade or so?
louis wrote:
You now seem to be trying to load the dice by referring to a (singular) fast reactor. What - no batteries? No back up? All you have got is a static mission on a knife edge, dependent on that one reactor not failing them.
I proposed sending a pair of Kilopower reactors to the surface. The pair of fission reactors provide redundancy. I also proposed sending a small tracked vehicle equipped with a permanent battery and homopolar generator. That vehicle will also be capable of providing continuous electrical power for the astronauts. It'll provide more continuous power than both reactors with far less mass than solar or nuclear. I want to land everything with HIAD and AF-M315E monopropellant. All mission component masses are around 5t, except the ascent stage. If micro capsules are developed to hold one or two astronauts, then the ascent stages can mass around 5t, too.
The technologies I favor to provide electrical power for mobile surface exploration vs bases vs colonies all vary because some technologies are more suitable than others for specific use cases.

kbd512 · 2017-06-04 21:10:51

louis wrote:

The numbers do change. Kbd, who supports nuclear, is quoting 250 W per Kg for solar panel and SpaceNut supports that figure.

Orbital ATK and NASA support the 250W/kg for their MegaFlex PV panels at 1AU distances. If you go further out, then you have to compensate by using a larger and therefore heavier array to produce a given level of output. There are some relatively simple equations that govern output achievable using a given array technology with a given surface area. Atmospheric effects complicate the matter somewhat, but any mission planner needs to know the lower bounds on input wattage to compute the array size required to guarantee a given level of output. Producing more power is a bonus, but the lower limit on mass to be allocated to guarantee minimum output won't be a negotiable mass allocation for them.

The lower limit on input wattage happens to mandate the use of a substantially more massive array. Again, it's not about what anyone wants. NASA won't bet the lives of their astronauts on the power output that can generally be achieved.

louis wrote:

Giving a figure for the nuclear core of a reactor is absolutely meaningless. We need a total mass figure. Sounds like you are another "soloist" when it comes to nuclear - you are just going to have a single nuclear reactor? Wow, I admire your bravery on behalf of the poor crew who are going to front up your bravery. What if it doesn't work for some reason? You appear to be claiming that something as well established as a methane generator can go wrong but a nuclear reactor/generator cannot go wrong...

The total mass for Kilopower is 1545kg. That figure doesn't include a power cable or power distribution equipment.

The "record" for RTG's, which are glorified heat engines, functioning as intended in space is 100%. There's never been a failure. Kilopower is only a slightly more glorified heat engine. I can't think of any failures of ATK's UltraFlex, either. On that note, I seriously doubt MegaFlex will fail once development and flight qualification of that technology has been completed. NASA and their contractors test the hell out of these things to ensure they don't fail.

kbd512 · 2017-06-04 22:33:02

louis wrote:

The water is virtually everywhere! At Chryse Planitia, my favoured landing zone, it's about 6% of the regolith. You just take a 100 Kg of regolith, heat it up and you have 6 kgs of water. It couldn't be more simple!

No argument there, but we still don't need the complication of something that requires cryogenic fuel and oxidizer storage for an exploration mission. For a base or colony, we should spend the money develop a methalox plant. Cryocoolers are power-intensive devices, so ballpark the continuous electrical power required to assure that the colonists' hard work doesn't simply evaporate into thin air.

Are you making rocket propellants or electrical power?

louis wrote:

Are you suggesting 2 x 10 Kw nuclear units? What if one fails? You are down to 10 Kw constant?

10kWe isn't enough for a two astronaut exploration team?

I want to send six astronauts per opportunity in pairs. Each pair of astronauts is assigned a grid to explore to characterize local resources, study the geology in their region, and to search for signs of life. That should maximize exploration opportunities.

louis wrote:

You have a particular vision of nuclear power that may incorporate PV (though I don't recall you mentioning what tonnage) but others do not.

I want to use PV panels to provide power for the transits to and from Mars.

louis wrote:

You talk about me referencing plants that don't exist while you and others reference KiloPower and SAFE 400 units that also don't exist!

There are active development programs for both MegaFlex and Kilopower. Neither are flight qualified systems yet, but NASA has multiple uses for both and a strong incentive to flight qualify both systems. There are no active development programs for a methalox plant. NASA has yet to flight qualify a cryocooler for long duration cryogen storage. After that happens, there could be funding for methalox plants. Before that happens, there won't be an application for a technology that doesn't exist.

DOE built and tested a 100We fission reactor as a MMRTG replacement. It hasn't flown in space yet, but it's arguably a more "real" piece of hardware than a methalox plant since someone actually built one (and I'm not talking about a thermal demonstrator, I mean they loaded a block of HEU into the unit and took the device critical). It worked. Period. That effort cost a little over half a million dollars. NASA doesn't want to pay hundreds of millions of dollars for Pu238. DOE has hundreds of tons of HEU in storage. Kilopower was the solution they came up with. The Kilopower demonstrator unit produces 4kWe. They're ground testing it later this year.

louis wrote:

Well as you said to me, I suggest you lay out in detail your mission proposal as reagards energy with detailed mass calculations. Then we can examine exactly what is you are putting forward. On the face of it, though, 20 Kwes constant doesn't sound good enough.

I want to send six astronauts in pairs to Mars using Falcon Heavy, New Glenn, or Vulcan Heavy. Falcon Heavy hasn't flown yet, so we could pretend it doesn't exist, but the flight hardware for the first qualification flight is at the cape and they've test fired the core and boosters. Falcon Heavy is going to fly, no matter what anyone thinks to the contrary. New Glenn and Vulcan are also going to fly. We have lots of uses for all three and that's why they're being developed.

I want to send a Cygnus surface habitat module and consumables (5,000kg), a pair of fission reactors (3,090kg), a light tracked vehicle (5,000kg), and an ascent vehicle (5,000kg) for each pair of astronauts using heavy lift rockets that have commercial applications. All of that would be delivered during the first launch opportunity.

If permanent batteries work as well as I already know they do from testing, then we can skip both fission reactors and solar panels for surface power to save mass and cost. I'm not in favor of spending money on anything just for the sake of doing so. As of today, development of MegaFlex and Kilopower is much further along than other competing technologies.

The astronauts can go to Mars in Dragon 2 and Cygnus with a SEP powered service module during the second launch opportunity. The ascent and kick stages can use NTO/MMH burning AJ-10-190 engine variants. AJ-10-190 flew on every STS mission and the engine was a derivative of the engine in the LEM. In other words, it's flight proven technology. I want to use HIAD (see the HEART experiment intended to reenter Cygnus on Earth and Mars) and AF-M315E monopropellant for a propulsive landing.

There are a number of threads on these forums where I've laid out my plans in detail. Mission architecture, component masses, launch schedules, and concept of operations are included. The general idea was to use as much of the stuff we already spent the money to develop to accomplish as much exploration as we reasonably can for minimal cost. If better technology comes along, great. If not, we already have most of the hardware required. Right now, we need better life support equipment and we need Congress to realize that NASA can't get people to Mars using inordinately expensive vehicles like SLS and Orion unless NASA's budget is substantially increased.

louis · 2017-06-05 09:18:22

I personally don't favour propellant production for Mission One. I would probably land propellant with the Mission Two series of landings.

I think there are advantages in keeping six people in relatively close proximity. A lot of the local prospecting could be done by a small scale rocket hopper with follow up mission by a pressurised Rover.

KiloPower sounds like it is at the same stage of development as some advance solar panels.

Do you have a link to the development of these "permanent" batteries you are referencing?

kbd512 wrote:

louis wrote:
The water is virtually everywhere! At Chryse Planitia, my favoured landing zone, it's about 6% of the regolith. You just take a 100 Kg of regolith, heat it up and you have 6 kgs of water. It couldn't be more simple!
No argument there, but we still don't need the complication of something that requires cryogenic fuel and oxidizer storage for an exploration mission. For a base or colony, we should spend the money develop a methalox plant. Cryocoolers are power-intensive devices, so ballpark the continuous electrical power required to assure that the colonists' hard work doesn't simply evaporate into thin air.
Are you making rocket propellants or electrical power?
louis wrote:
Are you suggesting 2 x 10 Kw nuclear units? What if one fails? You are down to 10 Kw constant?
10kWe isn't enough for a two astronaut exploration team?
I want to send six astronauts per opportunity in pairs. Each pair of astronauts is assigned a grid to explore to characterize local resources, study the geology in their region, and to search for signs of life. That should maximize exploration opportunities.
louis wrote:
You have a particular vision of nuclear power that may incorporate PV (though I don't recall you mentioning what tonnage) but others do not.
I want to use PV panels to provide power for the transits to and from Mars.
louis wrote:
You talk about me referencing plants that don't exist while you and others reference KiloPower and SAFE 400 units that also don't exist!
There are active development programs for both MegaFlex and Kilopower. Neither are flight qualified systems yet, but NASA has multiple uses for both and a strong incentive to flight qualify both systems. There are no active development programs for a methalox plant. NASA has yet to flight qualify a cryocooler for long duration cryogen storage. After that happens, there could be funding for methalox plants. Before that happens, there won't be an application for a technology that doesn't exist.
DOE built and tested a 100We fission reactor as a MMRTG replacement. It hasn't flown in space yet, but it's arguably a more "real" piece of hardware than a methalox plant since someone actually built one (and I'm not talking about a thermal demonstrator, I mean they loaded a block of HEU into the unit and took the device critical). It worked. Period. That effort cost a little over half a million dollars. NASA doesn't want to pay hundreds of millions of dollars for Pu238. DOE has hundreds of tons of HEU in storage. Kilopower was the solution they came up with. The Kilopower demonstrator unit produces 4kWe. They're ground testing it later this year.
louis wrote:
Well as you said to me, I suggest you lay out in detail your mission proposal as reagards energy with detailed mass calculations. Then we can examine exactly what is you are putting forward. On the face of it, though, 20 Kwes constant doesn't sound good enough.
I want to send six astronauts in pairs to Mars using Falcon Heavy, New Glenn, or Vulcan Heavy. Falcon Heavy hasn't flown yet, so we could pretend it doesn't exist, but the flight hardware for the first qualification flight is at the cape and they've test fired the core and boosters. Falcon Heavy is going to fly, no matter what anyone thinks to the contrary. New Glenn and Vulcan are also going to fly. We have lots of uses for all three and that's why they're being developed.
I want to send a Cygnus surface habitat module and consumables (5,000kg), a pair of fission reactors (3,090kg), a light tracked vehicle (5,000kg), and an ascent vehicle (5,000kg) for each pair of astronauts using heavy lift rockets that have commercial applications. All of that would be delivered during the first launch opportunity.
If permanent batteries work as well as I already know they do from testing, then we can skip both fission reactors and solar panels for surface power to save mass and cost. I'm not in favor of spending money on anything just for the sake of doing so. As of today, development of MegaFlex and Kilopower is much further along than other competing technologies.
The astronauts can go to Mars in Dragon 2 and Cygnus with a SEP powered service module during the second launch opportunity. The ascent and kick stages can use NTO/MMH burning AJ-10-190 engine variants. AJ-10-190 flew on every STS mission and the engine was a derivative of the engine in the LEM. In other words, it's flight proven technology. I want to use HIAD (see the HEART experiment intended to reenter Cygnus on Earth and Mars) and AF-M315E monopropellant for a propulsive landing.
There are a number of threads on these forums where I've laid out my plans in detail. Mission architecture, component masses, launch schedules, and concept of operations are included. The general idea was to use as much of the stuff we already spent the money to develop to accomplish as much exploration as we reasonably can for minimal cost. If better technology comes along, great. If not, we already have most of the hardware required. Right now, we need better life support equipment and we need Congress to realize that NASA can't get people to Mars using inordinately expensive vehicles like SLS and Orion unless NASA's budget is substantially increased.

Oldfart1939 · 2017-06-05 11:34:28

louis wrote:

I personally don't favour propellant production for Mission One. I would probably land propellant with the Mission Two series of landings.

Louis, my mission architecture requires only production of LOX, and no Methane production. I suggest bringing Aerozine-50 as the fuel, but doing USRU and a Moxie unit for the oxidizer production. That subsequently reduces the energy draw-down, and simplifies the mission.

Louis wrote:

I think there are advantages in keeping six people in relatively close proximity. A lot of the local prospecting could be done by a small scale rocket hopper with follow up mission by a pressurised Rover.

I agree that keeping the crew of 6 or 7 together, would also decrease the complexity of Mission One. Question: where is the fuel for the rocket hopper coming from? My prior suggestion was a solar-electric rover. Granted, we can't cover much area in one, but simply "getting there, staying 18 months, and getting back to Earth," would be the priority--would it not?

louis · 2017-06-05 12:05:57

I think with the solar option (see Going Solar thread) we will have plenty of energy available for methane/oxygen production. I am thinking of an automated rocket hopper.

https://phys.org/news/2011-02-fleet-inl … iftly.html

The above article suggests "a mid-sized hopper, about as heavy as an average American male, could travel five or six kilometers, or more than three miles, in a single bound." So maybe 180 pound craft could fly up to 2.5 Kms and return . Could be used independently or with a Rover. Generally I would think we wouldn't be exploring much more than about 100 sq. Kms around the base on Mission One.

Oldfart1939 wrote:

I agree that keeping the crew of 6 or 7 together, would also decrease the complexity of Mission One. Question: where is the fuel for the rocket hopper coming from? My prior suggestion was a solar-electric rover. Granted, we can't cover much area in one, but simply "getting there, staying 18 months, and getting back to Earth," would be the priority--would it not?

Last edited by louis (2017-06-05 12:06:16)

elderflower · 2017-06-06 07:23:40

Hopper fuel can be LCO and LOX. Its not very good but it could be used for a rocket hopper and can be produced by a single device. The same one that is making LOX for the return trip with the addition of CO capture and liquefaction.
First mission should have return fuel and oxidiser already in place, so proof of ISRU LOX facility by the first mission will allow its use by the second and subsequent missions.
I don't think hoppers will be needed before the second mission.

louis · 2017-06-06 07:31:24

I presume methane and oxygen are also OK?

A hopper won't be absolutely necessary. But it could help identify sites rich in particular minerals we are looking for. If the mass budget allows, I'd take one on Mission One.

elderflower wrote:

Hopper fuel can be LCO and LOX. Its not very good but it could be used for a rocket hopper and can be produced by a single device. The same one that is making LOX for the return trip with the addition of CO capture and liquefaction.
First mission should have return fuel and oxidiser already in place, so proof of ISRU LOX facility by the first mission will allow its use by the second and subsequent missions.
I don't think hoppers will be needed before the second mission.

elderflower · 2017-06-06 07:49:54

Methane and oxygen are much better as rocket fuel, but you need to get hydrogen or bring it and then make methane using Mars CO2. It adds a lot of complication to the whole system, which you don't need if you only wish to travel a few km.
Bringing Hydrogen as LH2 would involve a very large tank, and there probably wouldn't be much left after a long transfer, due to boil-off. Maybe pentaborane or methane or hydrazine derivative would be brought instead, then you don't need to make the fuel as any of these could be used as such. If you want to make better fuel than CO in situ you really need to find water to electrolise.

louis · 2017-06-06 09:43:13

Once humans are there, using electrolysis to make hydrogen from the plentiful water ice in the regolith should be simple.
Water ice is 6% of the regolith in north east Chryse Planitia (about 25 degrees north). Should be a simple matter to heat the soil and condense out the water. For every 100 Kgs you get 6 kgs of water and from that 0.78 Kg of hydrogen. So, if you process a tonne of regolith you get nearly 8 kgs of hydrogen. We could probably process a tonne a sol for a couple of months and produce nearly 500 kgs of hydrogen.

elderflower wrote:

Methane and oxygen are much better as rocket fuel, but you need to get hydrogen or bring it and then make methane using Mars CO2. It adds a lot of complication to the whole system, which you don't need if you only wish to travel a few km.
Bringing Hydrogen as LH2 would involve a very large tank, and there probably wouldn't be much left after a long transfer, due to boil-off. Maybe pentaborane or methane or hydrazine derivative would be brought instead, then you don't need to make the fuel as any of these could be used as such. If you want to make better fuel than CO in situ you really need to find water to electrolise.

Oldfart1939 · 2017-06-06 09:54:25

elderflower wrote:

Methane and oxygen are much better as rocket fuel, but you need to get hydrogen or bring it and then make methane using Mars CO2. It adds a lot of complication to the whole system, which you don't need if you only wish to travel a few km.
Bringing Hydrogen as LH2 would involve a very large tank, and there probably wouldn't be much left after a long transfer, due to boil-off. Maybe pentaborane or methane or hydrazine derivative would be brought instead, then you don't need to make the fuel as any of these could be used as such. If you want to make better fuel than CO in situ you really need to find water to electrolise.

See my post # 67.

SpaceNut · 2019-07-14 16:03:39

This topic is simular to the solar heat enegines of which I had been describing.

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