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

louis · 2018-06-02 18:32:23

Are you really claiming that Space X would raise zero dollars sponsorship or TV rights for a serious attempt at a Mars landing? Sponsorship follows reality - the closer Space X get to a mission the more the money will roll in.

One thing you leave out is a Mars simulation mission. IMO Space X will have to have a Mars simulation mission, probably involving a Moon landing before they try the real thing re Mars.

Oldfart1939 wrote:

If we stop to do a bit of bookkeeping on what's necessary for the first flights to Mars: (1) grasshopper flights of both booster stage and of the BFS Mars lander; (2) LEO launch and recovery of the BFS and the BFR booster stages. But then what? We need at least 2 more boosters and a couple fuel tankers, followed by: (1) demonstration of in-orbit refueling; (2) launch of a cargo freighter to Mars; (3) successful landing and robotics deployment.
All of these are simply starters. It says nothing about the necessary mars infrastructure facilitating return of the first experimental lander(s). That's an awful lot to (1) accomplish; (2) get it paid for with zero return from the expenditure of these funds.
Color me skeptical, not pessimistic.

kbd512 · 2018-06-02 20:53:36

Louis,

To do what we're talking about doing, TV sponsorship won't come close to paying for it. If the technologies that enable us to go to Mars also enable us to economically return chunks of asteroids that contain Platinum, Gold, Silver, or diamonds to Earth, then humanity can afford this second branch of human civilization. The people with deep pockets don't have pockets nearly deep enough to pay for everything. They're putting maximum effort towards the goal, and that's laudable, but the cost of the technologies involved must be imminently reasonable, there have to be paying customers (price point determines that in the real world), and governments must invest in the research required to enable humanity to leave the cradle.

I'm not skeptical or pessimistic, but I want SpaceX to succeed where NASA hasn't. Whenever someone proposes something that strains the capabilities of available technology, I demand math and logic based answers to fundamental questions like...

Does the technology set to do what's being proposed actually exist (not notionally or on paper, but in the form of a prototype that's been proven to work or a commercial / industrial system in routine use)?

If not, then how much development work remains to achieve the goal (admittedly difficult to pin down, but given past progress, what is the likely rate of future progress)?

How much is accomplishing the objective expected to cost?

What is the expected return on investment if the objective is accomplished?

What is the timeframe associated with the expected return on investment?

Everyone should ask such questions whenever someone proposes doing something fundamentally new that depends upon the answers to those questions. It's part of a process by which risks and issues with technology are mitigated to ensure a successful outcome.

For example, I continually review available and proven electrical energy production and storage technologies to determine how energy needs can be met in a practical and cost-effective manner. Apart from reality based calculation of what a particular technology can reasonably provide, I don't have any preferences for one technology over another. That said, whatever technology set is used had better work and it had better scale well, or a project as all-encompassing as starting another branch of human civilization on another planet will fail. If something doesn't work for an intended purpose, then I'm going to point out the problems and insist that someone else either offer up a realistic solution or admit to themselves that what they wanted to do may not work in the manner intended.

Oldfart1939 · 2018-06-02 23:46:33

Louis-

I was planning on composing something almost identical to what kbd512 already wrote. Commercial sponsorships may garner fees in the millions, but we're 3 orders of magnitude beyond that in necessary funding. What Musk is proposing is going to run into a lot more than the net worth of SpaceX, which is in today's money around $27 or $28 Billion. Bezos is putting roughly $1 Billion per year into Blue Origin; that's enough to slowly develop the New Glenn, but he'd need to sell a bunch more of his Amazon stock to fully fund a moon mission.

louis · 2018-06-03 06:58:22

Oldfart and kbd,

I think you are underestimating the potential for sponsorship (simply one revenue stream) and overestimating the costs.

NBC is to pay over $4 billion coverage for four Olympic Games (summer and winter) over two Olympic cyles. And that's just for N America I believe. Across the globe TV right sales would be raking in some further billions. That's just TV rights. Then you have all the sponsorship of teams and individual athletes. Coca Cola and Nike have annual advertising and marketing budgets in the billions - Coca Cola's is $3 billion I believe.

The Mars Mission will be one of the biggest TV and media events in history up there with the Moon landing, World Cup and Olympics.
It is quite realistic to think of sponsorship deals bringing in at least $10 billion over ten years in my view. There will be ongoing sponsorship as well for various exploration missions.

That's before you look at all the other potential revenue streams. First up will be scientific experiments. Thousands of Universities across the globe will pay large sums to have their experiments taken to Mars or will pay for regolith and other samples. Secondly, I believe a number of Space Agencies - NASA included - will be interested in sending their people to Mars to undertake research and exploration.
Payments for research and experimentation will pull in further billions.

Then I think there is no doubt some leading universities will want to be the first to establish a presence on Mars, a kind of post grad teaching and research faculty. If life is found on Mars, there will a research gold rush for sure. The universities will be dependent on Space X to provide transport habitation, energy and life support - they will be paying a large per annum sum for those services, billions over a decade.

There are many other revenue streams one can anticipate: e.g. creation of art objects on Mars, use of Mars to store digital copies of libraries on Earth, luxury manufactures ( Rolex watches assembled on Mars with Mars material incorporated is one suggestion I have made)...

I think the "First on Mars" phenomenon will become a huge attractant. This will be like the dot.com era when everyone wanted to set up a website business or the 19th century railway boom when every town wanted its railway connection to the rest of the country....There will be huge amount of free publicity for anyone who can say they've done something "first" on Mars. Organise the first Mars Olympics and the media will be all over it. Open up an ATM machine on Mars and your bank will get a load of publicity. Make the first bottle of wine on Mars and your company will get huge publicity. Set up a dress design company on Mars and you will get fantastic publicity. Make the first film on Mars and it is guaranteed publicity. In many cases, firms won't do things particularly for profit but simply to deny the opposition taking the credit. If I'm heading up Ford I might not want to go to the expense of paying Space X huge amounts to send the first commercial car to Mars, but do I want to see Toyota beat Ford to it? Do I really want to see that photo of that Toyota climbing Olympus Mons emblazoned everywhere for the next five years? Reluctantly I might decide to pay Space X $300 million to take our car there and beat Toyota. You see? The phenomenon of FOM - "First on Mars" - is going to be BIG.

Oldfart1939 · 2018-06-03 08:32:19

Uhhh...Louis!

The first car company on Mars will undoubtedly be Tesla. Another problem with your enthusiastic view of sponserships , is the Olympics are a "sure winner." The first flight to Mars will be fraught with difficulties and high risk. No advertiser wants to sponser an event where there's a better than 50% that it will be disastrous. OK, Maybe Coca Cola would pay some Big Bucks to have a SpaceX booster stage painted like Coke can, or maybe Budweiser or Coors. Maybe Nike would pony up some dough if they were involved in making the Mars explorer's footgear? This kind of financial support is highly volatile, and can evaporate almost in a heartbeat. Any disaster and the advertisers will be fleeing the scene for the exits.

SpaceNut · 2018-06-03 10:40:48

Loius wrote:

NBC is to pay over $4 billion coverage for four Olympic Games (summer and winter) over two Olympic cyles.

That is done to create a monoploy for the field of the showing to which all others must buy the live fields from them, all advertises for the 30 sec commercials must also do the same to be seen during the broadcasts. Its about NBC making a profit on the investment to have total rights for broadcasting the Olympics.

We need to ask whom gets the initial feed money not whom wants in....

What you have been thinking of is the private Nascar model of funding for the racer and not of Nascar in general for how you are seeing what Space x could do....Space x is the race car driver and not the upper level of space gateway out of LEO , to the Moon or even Mars as there is no one that owns them or the rights under the treaty agreements.

louis · 2018-06-03 13:58:26

I expect sponsorship deals would be staged for Mission One, rather than being up front payments. I doubt Space X would have any problem arranging sponsorship deals once they had successfully completed a trial run based on the Moon. Sponsorship deals do go wrong all the time...eg athletes' reputations crash because of positive drug tests or other issues.

Yes I did think about Tesla as I wrote it but of course it is a separate company and I don't know if it could compete with bids from Ford or Toyota. I think the imperative for Space X will be to generate revenue.

I think any sponsorship deal would no doubt have contract break clauses in event of launch failure, crew deaths etc. But I think you are making an assumption in thinking that would necessarily mean no money - it would mean the sponsor might simply wish then to dissociate themselves.

Let's suppose Space X signed a ten year $5 billion sponsorship package. It would have all sorts of aspects such logo featuring on backboards at press conferences, including the name Coca Cola in official descriptions of the mission and so on, plus product placement in official photos. There might be a $1 billion payment up front and then annual payments of $400 million with break clauses in event of critical negative events.

There would probably be similar break clauses re TV rights.

But I don't see the need for break clauses per se for other sponsorhip such as footwear, crew leisure clothing, energy bars, automotive, computers, mobile phones and so on. There you would expect the companies to take the risk. They might be shorter deals, maybe 5 years rather than 4. Companies like Nike, Adidas, Toyota, have huge advertising budgets. They can afford to take the risk.

Oldfart1939 wrote:

Uhhh...Louis!
The first car company on Mars will undoubtedly be Tesla. Another problem with your enthusiastic view of sponserships , is the Olympics are a "sure winner." The first flight to Mars will be fraught with difficulties and high risk. No advertiser wants to sponser an event where there's a better than 50% that it will be disastrous. OK, Maybe Coca Cola would pay some Big Bucks to have a SpaceX booster stage painted like Coke can, or maybe Budweiser or Coors. Maybe Nike would pony up some dough if they were involved in making the Mars explorer's footgear? This kind of financial support is highly volatile, and can evaporate almost in a heartbeat. Any disaster and the advertisers will be fleeing the scene for the exits.

kbd512 · 2018-06-04 05:14:02

NASA's proper function is to research / develop / prototype / test / refine the enabling technologies required for these missions, coordinate inspections / launch services / support services / contracts, and to provide real astronauts, rather than civilians who want to pretend to be Buck Rogers, to create the infrastructure required to explore and expand civilization into space. I would like nothing more than for NASA to exit the rocket and spacecraft design business, especially since corporations have provided that hardware to the agency since it existed, and to focus on development of everything required to get to the moon and Mars. Anything that works on the moon will also work on Mars. The moon is the severe acid test required to confirm the proper function of the hardware set before the Mars test begins. For any of this plan to work well enough to achieve the desired goal in a reasonable timeframe, there must be different vehicles optimized for specific functions. The requirements are so divergent for one vehicle to perform all functions as to be impractical at best, if not impossible.

Off the top of my head, SpaceX wants a single basic vehicle design to do all of the following:

Earth-Centric
1. reusable upper stage / shuttle
2. reusable suborbital transport

Lunar-Centric
3. LEO-to-LLO
4. LLO-to-moon (on unprepared surfaces)
5. LLO-to-Earth

Mars-Centric
6. LEO-to-LMO
7. LMO-to-Mars (on unprepared surfaces)
8. Mars-to-LMO
9. LMO-to-Earth

Anyone else here think this looks a lot like all the Space Shuttle design compromises that were made to satisfy everyone?

Why not design variant vehicles and a purpose built interplanetary transport for humans that all stay in their ideal operating environments?

I’m sure there’s enough here to upset everyone since Elon Musk’s approach has been questioned, but here’s what I think:

1. There’s nothing inherently wrong with the SpaceX design of the BFR, but the upper stage could benefit significantly from the use of a more energetic and lighter fuel, namely LH2. I think BFS should be a LOX/LH2 powered vehicle optimized for short duration flights to and from low orbit around the Earth, the moon, or Mars. That may seem counter-intuitive at first, but the total tankage volume required by a LOX/LH2 powered BFS is actually less than that required for LOX/LCH4. Further, Integrated Vehicle Fluids, or IVF, eliminates the need for separate systems for electrical power (batteries and solar panels), propellant pressurization, and reaction control systems that use storable chemical propellants. It drastically simplifies the design of the vehicle and eliminates significant associated systems mass. The boil off from the propellant tanks powers a small internal combustion engine that provides electrical power, reaction control, and tank pressurization / de-pressurization. It turns out that LOX/LH2 works really well in a small internal combustion engine and eliminates most of the problems associated with liquid hydrocarbon fuels.

Fundamentals of Cryogenics

LOX/CH4 and LOX/LH2 Heavy Launch Vehicle comparison

An Integrated Vehicle Propulsion and Power System for Long Duration Cryogenic Spaceflight

Realistic Near-Term Propellant Depots: Implementation of a Critical Spacefaring Capability

* BFS length more appropriate for vertical landings, especially on unprepared surfaces, so payload volume accommodates passengers or cargo or propellant only
* If SpaceX, NASA, or others are insistent on using chemical propulsion, then the humans launch last, after a propellant depot has been loaded via a series of BFS tanker variants
* No requirement for multiple docking events for on-orbit transfers of cryogenic propellants to occur in rapid succession
* No requirement for long duration habitation in deep space
* CO2 is only available on Earth and on Mars, but water is available everywhere
* BFS suborbital flights without the use of the booster are still possible, requires far less fuel, and are potentially less dangerous to the passengers

Proton OnSite’s (recently acquired by NEL Hydrogen) M Series PEM water electrolyzers have accumulated 500,000 operating hours with zero failures of any kind. Further, this technology was specifically designed to function with intermittent power from solar panels. Last but not least, the M Series fits inside a standard shipping container and generates 864kg of H2 per day using 2MWe of input power. It does not require extensive space testing and validation because it’s already been tested in space and proven to work. Combined with 2MWe thin film solar arrays, it could fill the tanks of a LOX/LH2 powered BFS in a matter of days. This is more in line with a normal launch and boil off losses can be converted into electrical power to remove heat and provide backup electrical power at night. The process may be energy intensive, but it’s commercial technology that’s light and compact enough to deliver to Mars. It doesn’t require months of continuous operation to complete, either, thus starts and stops to accommodate power availability are permissible.

Wide Spread Adaption of Competitive Hydrogen Solution

Nel ASA presentation

Proton OnSite M Series

2. The interplanetary transport vehicle for humans must be a 50m+ radius spinning inflatable wheel attached to a rigid metal alloy service module via inflatable spokes. The service module will contain life support systems, the consumables and water tanks that serve as the radiation shelter to protect against solar flares, a distilled water fuel tank for the MPD thruster, and a 1MWe+ thin film solar array to power the MPD thruster. The habitable portion of the ITV spins. The attached solar power array, fuel tank, and MPD thruster do not. This keeps the masses as low as feasible while maintaining structural integrity. The solar array will be constructed on orbit to eliminate the need for the dead mass and complexity of deployment systems intended to survive launch acceleration loads.

Gravity and Acceleration:
* Humans need artificial gravity to assure survival during the reentry events, no acceptable substitutes have been identified, and a 50m radius permits 1g acceleration at ~4rpm and is the maximum that untrained humans could tolerate in actual testing in the 1970's
* The comparatively sedate acceleration forces from electric propulsion does not mandate a vehicle solar array design that can withstand the substantial force imparted by chemical propulsion
* The ITV stays in space and propulsively travels from orbit to orbit, so no requirement to withstand the heat and aerodynamic forces associated with reentry or aerobraking exists

Efficiency:
* 1MWe input permits a MPD thruster to operate with good efficiency and to produce more thrust than a nested Hall-effect thruster with the same level of input power, producing transit times on par with the best chemical rockets, but with Isp well into the thousands of seconds
* The MPD thruster uses H2 as propellant, but only a few tens of grams per second at most, so water electrolysis can provide the necessary input mass to negate the need to refrigerate or store LH2
* The humans need the O2 and potentially H2O to replenish losses from CO2 scrubbers, since O2 and H2O is dumped overboard during CO2 amine swing bed regeneration follow CO2 scrubbing
* Transfer of several tons of water to refuel is not a major event and no highly pressurized Nobel gases or cryogens are required

Technological Capability:
* No advanced technology is at work here, just lots of electrical power, and MPD thrusters have been extensively tested by NASA and ROSCOSMOS up to power levels of 1MWe
* Available long duration space flight proven thin film solar cells attain power-to-weight ratios exceeding notional traveling wave direct energy conversion from fusion reactors (1,125We/kg to 1,400We/kg for current production cells), do not mandate the use of large and heavy radiator assemblies, and can be optimized to provide power at the correct voltage and amperage to limit the mass of the equipment required to condition the power produced
* The thin film arrays do not stop producing power when punctured or torn by space debris or rough handling and produce substantially more power when not optimally oriented into the Sun in comparison to competing wafer-based semiconductor technologies and no other electrical power options available are remotely comparable in terms of dollars spent per watts of electrical power produced
* Tethers Unlimited Inc's "trusselator" truss fabrication machine / robot can produce circular truss structures of a kilometer or more in diameter for a weight of tens of grams per 10m of truss structure

3. The BFS must remain at and operate from either the Earth, the moon, or Mars, but not all three. The entire point behind BFS was to design a reusable vehicle that could land anywhere. Realistically, no lander vehicle that travels to the moon or Mars will come back to Earth. It costs too much to send BFS all the way there and back and then you have to send out another BFS to replace the BFS that returned to Earth. Any maintenance that needs to be done to the BFS to reuse it must be achievable where the vehicle is located, or there’s a high probability we’re never getting it back.

* The issues associated with achieving orbit and surviving reentry are substantial in their own right and no design requirements beyond that should be imposed upon the vehicle, else mass, cost, and complexity problems start to mimic those encountered by the F-35 program
* The BFS heat shielding mass can be optimized for the locale the vehicles is designated to operate from to reduce refueling requirements

louis · 2018-06-04 09:44:08

kbd512 wrote:

Proton OnSite’s (recently acquired by NEL Hydrogen) M Series PEM water electrolyzers have accumulated 500,000 operating hours with zero failures of any kind. Further, this technology was specifically designed to function with intermittent power from solar panels. Last but not least, the M Series fits inside a standard shipping container and generates 864kg of H2 per day using 2MWe of input power. It does not require extensive space testing and validation because it’s already been tested in space and proven to work. Combined with 2MWe thin film solar arrays, it could fill the tanks of a LOX/LH2 powered BFS in a matter of days. This is more in line with a normal launch and boil off losses can be converted into electrical power to remove heat and provide backup electrical power at night. The process may be energy intensive, but it’s commercial technology that’s light and compact enough to deliver to Mars. It doesn’t require months of continuous operation to complete, either, thus starts and stops to accommodate power availability are permissible.
Proton OnSite M Series

I like the sound of that.

Humans need artificial gravity to assure survival during the reentry events

I would say that is at least unproven as of now and, in my view, will be disproved during testing for the BFR Mars mission.

Many who advocate AG seem to assume a journey time to Mars of 6-9 months. But I have seen other references to 3-4 months. I don't see a journey time of under 6 months as a serious impediment, although - clearly - longer term, an AG system will be desirable for carrying people of ordinary levels of fitness.

The BFS must remain at and operate from either the Earth, the moon, or Mars, but not all three. The entire point behind BFS was to design a reusable vehicle that could land anywhere. Realistically, no lander vehicle that travels to the moon or Mars will come back to Earth. It costs too much to send BFS all the way there and back and then you have to send out another BFS to replace the BFS that returned to Earth. Any maintenance that needs to be done to the BFS to reuse it must be achievable where the vehicle is located, or there’s a high probability we’re never getting it back.

Not quite sure what this means. Surely the BFR is being designed to operate at a max of Earth-Mars and back with minimal maintenance?
What's wrong with that in principle. There will be two crewed BFRs on Mission One...which I imagine is partly to build in a level of failsafeness. I don't understand why it would "cost too much".

kbd512 · 2018-06-04 12:38:37

Louis,

I advocate for artificial gravity because it doesn't matter how long the passengers stay in space. If you can't cut the transit duration to 3 to 4 months, for whatever reason, then it still doesn't matter. If 3 to 4 months in microgravity is enough to seriously affect the average person, as opposed to a supremely physically fit and disciplined astronaut, it doesn't matter.

The mass of the vehicle is optimized for the protection of the crew, in terms of systems redundancy and radiation protection. It doesn't matter if it weighs a few extra tons because it's not a chemical rocket stage. It's built in modular sections that can be connected to each other to create a longer version of the same vehicle without substantial modification to the basic design. Everyone has seen the multiple tires on the rear axles of semi trucks. Same concept. Up to a point, you can add additional "tires" to support greater numbers of passengers. My arbitrary design point is 1,000 people in ten rotating sections since that's the maximum seating capacity of a single passenger carrying BFS variant. It's using heretofore unavailable plentiful, lightweight, and cheap solar arrays to overpower an electric propulsion system to whatever degree is required to achieve optimum Isp and thrust. If you must abort to Earth, then you have sufficient dV to come back. The propulsion system uses water, rather than cryogens / corrosive storable chemicals / rare gases, so there is no major issue with extended duration storage of the propellant.

My BFS concept uses the 3 primary variants of the upper stage (passenger, cargo, tanker) described by SpaceX. However, my concept uses 2 sub-variants of the passenger carrying variant that are intended to stay in their operating environment. The cargo and tanker variants are enlarged for greater payload volume and mass. The booster, the part I call BFR, generates enough thrust to deliver more LOX/LH2 than LOX/LCH4 propellant to an orbital propellant depot or other craft. It's still possible to use chemical propulsion, but there would be facilities constructed in orbit around Earth / moon / Mars for that purpose.

BFS Variant Concept:

Earth and Mars Crewed BFS (still 9m diameter, but shorter) - high speed point-to-point suborbital transport by itself or orbital transport atop the booster stage

Lunar and Asteroid Crewed BFS (still 9m diameter, but shorter) - no heat shield since there's no atmosphere; mass saved is more payload or less propellant

Earth Orbital Cargo BFS (13.5m diameter, same length as original concept) - holds bulky payloads or multiple satellites in an ejector rack assembly; satellite orbits raised using electrodynamic tethers, so the vehicle is optimized for maximum tonnage delivered to LEO

Earth Orbital Tanker BFS (13.5m diameter, same length as original concept) - holds larger LOX/LH2 tanks; rather than risk damage to the vehicle from tanking or require exceptionally precise docking, it uses a pair of retractable refueling probes to transfer propellants like a tanker aircraft

All vehicles use IVF so design tradeoffs are directly based upon available propellant capacity instead of payload mass and volume.

Need more electrical power to heat or cool something? Do the propellant calculation.

Need more dV for reaction control authority? Do the propellant calculation.

Need more dV to restart the engine to alter the orbit? Do the propellant calculation.

Need more time on station to complete an activity like capture of an aging satellite? Do the propellant calculation.

Mission planning becomes a propellant math calculation. You don't have to worry about whether or not you're in the Sun, how much battery power you have left, or if the RCS system still has enough propellant remaining to perform the task and de-orbit the vehicle. You have the required propellant in the main fuel tanks or you don't. It's a powerful concept for mission planning and a simple way to design a vehicle that doesn't require hundreds of extra engineers to design separate systems, with severe mass / volume / power constraints imposed upon them, that only get used during certain portions of the vehicle's operating regime.

Once BFS is fueled, the O2/H2 internal combustion engine APU provides electrical power to avionics, propellant tank and cabin pressurization, flight control authority, and main engine startup, just like a jet aircraft. There's no hard requirement for external power. Once the vehicle is fueled, it has power from gas pressure created by cryogen boil-off. That's more than sufficient to start the APU without the need for a battery. The APU is always running in flight and cryogens are always boiling off, as they always do in the real world. The operating characteristics are directly associated with propellant capacity, just like a jet aircraft.

Oldfart1939 · 2018-06-04 18:21:49

kbd512-
I like several to many of your details in your concept. I'll say my say now: To Louis--Having artificial gravity is absolutely mandatory for long term health. The loss of heart muscle tone and the weakening of bones through decalcification may not be devastating on the Earth to Mars journey, but it's fatal to returning crewmembers on the segment back to Earth. GW has been through the g forces needed for Earth atmosphere deceleration being 11 g. With decalcified rib cage and spinal column, we simply would NOT LIVE THROUGH THE EXPERIENCE.
I also disagree with the use of lH2 and LOX as the propellant couple. The use of lH2 is not good for the mission, due to the necessary fuel tank insulation mass penalties, in addition to the embrittlement of any metals brought in contact with it. The lCH4 is just an OK fuel, but my favorite is either Aerozine 50 or UDMH.

SpaceNut · 2018-06-04 19:06:52

Build something, get it up there from what can be assembled from all the inflatebles and cygnus we might want. What can be gotten and do some real science to prove its just got to be or man can not go. It only needs to be in orbit about a year to prove all that we would want to know....

kbd512 · 2018-06-04 19:56:38

Oldfart1939,

All recent operational experience with cryogenic fuel is LH2. All testing of new cryogen containers is done with LN2, then LH2, then whatever else you want to put in it. The devil is in the details and that's a completely valid point, but it's also the devil we know. The US space program is exceptionally well versed in LH2 use and it offers advantages in upper stages. I'm not a fan of solid rockets because I don't like engines we can't turn off.

LCH4 is clearly better for engine maintenance and that's important if you have dozens of engines to work on, but worse for mass and volume because it doesn't confer the bulk density and thermal stability advantages of RP-1 and Isp is still substantially lower than LH2, which increases the volume and mass of the upper stage, thereby decreasing total delivered tonnage for a given tank mass and volume.

A LOX/LH2 plant on Mars only requires water and PEM fuel cells run in reverse. Combined with thin film solar and small internal combustion engines for backup power at night, the entire solution is so small and light that a single BFS can deliver absolutely everything required to start ISPP on Mars.

The Sabatier reaction clearly works, but there's not much industrial scale Sabatier reactor use here on Earth and NASA is still fiddling with a system that can scale up for use in space. That's a shame because CO2 from coal plants can be combined with water to make methane to power gas turbine peaking plants. That's getting the most bang for your buck, but it's not cost effective.

Science Direct - Power-to-Methane: A state-of-the-art review

Science Direct - Industrial Scale Sabatier Reactor

Anthony Muscatello - ISRU - 19th Annual International Mars Society Convention

Industry is just now working on these things and yes, they could also be ready to go in another 10 years or so. However, PEM O2/H2 plants are already more compact and weighs less. NEL Hydrogen is working on making these things even more compact and efficient because it's something we need here on Earth.

SpaceNut · 2018-06-04 20:41:01

Would love to have a commercial Sabetier reactor as the artesian well water, I have for the home as it is full of iron, magnesium, sulfur and more having one would allow for a means to get clean water to drink without the cost of buying bottled water. Using solar to pump and electrolyis the dirty water would be where to start with using the garbage that will burn plus lawn waste would give plenty of feed Co2 and in the winter the added heating from wood would also be a boon to give plenty of it to make methane as well.

LH2/LOx has the ability to land greater masses on the moon or mars but its the boiloff time that is the issue for mars.

The hydrogen economy does work and is quite possible under safe made conditions to which most zoning boards and inspectors are ill equiped to deal with it in on a large scale. Solar was used by MIT long ago for just that purpose and there is a home that runs on hydrogen including there vehicles.

Oldfart1939 · 2018-06-04 21:26:20

My quibble against LH2 is strictly based on (1) the low density of the stuff, and (2) the boiloff rate that SpaceNut stated. For sure it has the highest Isp of all available liquid fuels, but NOT the highest Id; that niche is occupied by Hydrazine, N2H4. But that product is simply too dangerous in rockets to use, and is why UDMH is normally used by NASA in it's place. Aerozine 50 is equally safe and possibly cheaper with a similar Id. Looking at the Isp tables is seductive towards LH2, but in spite of the factors in it's favor, one needs to have long term storability for deep space missions.

louis · 2018-06-05 01:35:26

There's no evidence anywhere that Space X are proposing an 11G return.

Oldfart1939 wrote:

kbd512-
I like several to many of your details in your concept. I'll say my say now: To Louis--Having artificial gravity is absolutely mandatory for long term health. The loss of heart muscle tone and the weakening of bones through decalcification may not be devastating on the Earth to Mars journey, but it's fatal to returning crewmembers on the segment back to Earth. GW has been through the g forces needed for Earth atmosphere deceleration being 11 g. With decalcified rib cage and spinal column, we simply would NOT LIVE THROUGH THE EXPERIENCE.

Oldfart1939 · 2018-06-05 06:01:57

Louis-
It's not what they are planning, but simply a consequence of a direct atmospheric re entry from Mars. This is not me blowing smoke--just the physics as stated by GW, elsewhere.

kbd512 · 2018-06-05 15:24:55

Oldfart1939,

The Id of LOX/UDMH or Aerozine-50 is much better than LOX/LH2, but there's no Hydrazine plant on Mars and the Isp is nearly exactly the same as LOX/LCH4. That means the same vehicle dimensions for the same performance. Hydrazine still has thermal management requirements to prevent freezing. There's no way around cryogen storage requirements for a SSTO and that is what BFS is.

The latest testing of 100nm thick bi-layer Graphene Oxide demonstrates zero O2, H2, CO2, and H2O permeability in gas or liquid forms. It's a type of acid-based coating process that can almost or entirely eliminate Hydrogen embrittlement, dependent upon the thickness of the coating.

Impermeable Barrier Films and Protective Coatings Based on Reduced Graphene Oxide

LOX boil off can be virtually eliminated thanks to the heat carrying capacity of Hydrogen and the LH2 boil off on orbit can be limited to less than that required to provide attitude control and electrical power. MLI and IVF provides enough thermal stabilization of LH2 in Earth orbit to cause losses from attitude control and electrical power generation to exceed the losses that would occur from boil-off without MLI and IVF. Last I checked, attitude control and electrical power are always required.

Phase I Mars Colony Construction:

I've thought about the expanded diameter volume for the BFS-OT (Orbital Tanker) and BFS-OC (Orbital Cargo) variants. It's actually not necessary for what I had in mind, so all BFS variants will be the same diameter and the lander variants will be somewhat shorter by reducing payload to 100t, as more capability is not immediately required. The BFS-OC variant will repurpose ICPS upper stage hardware from SLS to create an Orbital Propellant Depot (OPD). BFS-OT will fill the OPD via a refueling probe before the first BFS-MP (Mars Passenger) and BFS-MC (Mars Cargo) fill their tanks. This means the crew and cargo stay on Earth until OPD product is available to send them to Mars.

8MWe (1,125W/kg to 1,400W/kg) Ascent Solar panels - 8,000kg (presumes some sort of plastic or graphene coating for electrostatic dust removal)

5km EmPowr Fill Underground Distribution Cable - 12,221kg; the 2.2MWe Proton Onsite M-Series (902kg H2 per 24hr continuous operation) only requires 2.2MWe (20kV 110A 3-Phase AC at 60Hz) for maximum output and this cabling is designed to handle 8MWe output, but probably need to go with heavier cabling for greater ampacity

Composite Truss materials - 1,000kg (many times more material than required)

10 Trusselator Robots - 1,000kg (only weighs about 100kg, but we're taking extras)

10 Big Dog Robots - 1,100kg (requires 11kWe from a single cylinder internal combustion engine; carries 180kg on Earth or 450kg on Mars)

1 Proton Onsite M400 PEM H2 Plant - 38,521kg (actual total mass of the plant with no mass optimization attempted; 26,000kg alone is power conversion equipment)

1 Multi-Cell 20,000 gallon PE water tank (enough for 200 hours of continuous M400 operation) - 1,650kg (mass derived from commercial 10,000 gallon PE tanks); 9kg of H2O required for 1kg of H2 (please tell me if that's correct, as I'm not a chemistry major) but we only need 6kg for the rocket, so we need to figure out what to do with all that extra O2 since dumping it would be a waste of material

38,521kg - H2 Plant and Water Management
12,221kg- PV farm power cabling
9,000kg - PV farm materials
5,500kg - 2.2MWe fuel cell (runs the process in reverse at night)
2,100kg - Robots
1,650kg - Water Storage

63,492kg - Total payload mass

I used 1,639lbs/1000ft for 25kV, 420A wiring (may need heavier wiring with greater ampacity or we’ll end up dumping a lot of power to ground for most of the day without batteries)

Backup Materials for Proposal:

Proton OnSite M400 Skid Technical Details:
Proton Onsite M Series Hydrogen Generation Technical Specifications

General Cable Electric Utility Power Cabling Product Guide:
General Cable - Electric Utility - Energy Products for Power Generation, Transmission, & Distribution

Hydrogenics 1MWe Hydrogen Fuel Cell Generator (not used here, just interesting that it weighs 32,000kg and produces 1MWe):

10,000 gallon food grade PE water tank:

10000 Gallon Plastic Water Storage Tank

SpaceNut or Oldfart1939 or whomever,

Any help with the energy economics of using 500Wh/kg Lithium-Polymer batteries (finally in commercial production) would be appreciated. 4,400kg of such batteries can store 2.2MWh, 52,800kg needed for 12 hours of backup.

Are we better off just refrigerating the LH2 at night and starting LH2 production the next day, or is there any benefit to 24/7 operation?

What if we just put another M400 in the human lander and just added a lot more solar panels?

FYI, all cargo is coming out of the landers. The LOX/LH2 plant will be emplaced behind regolith berms to protect them from the BFS launch. The solar panels are going to be several kilometers away from the launch site. The batteries will be located there, too. I see that I forgot the mass of the regolith movers and regolith collection tanks.

Oldfart1939 · 2018-06-05 20:45:17

kbd512-

I'm certain that Musk has settled on LCH4 as his fuel of choice, so we can banter about hydrazine derivatives and LH2 as much as we like. There aren't nearly the penalties of weight (mass) associated with keeping hydrazines warm enough to stay liquid as there are with insulation for LH2. And by the way, making UMDH isn't that difficult if there is some N2 available; it's storable for long term and will not boil off. Making UDMH is a straightforward 3 step process.

Last edited by Oldfart1939 (2018-06-05 22:38:36)

kbd512 · 2018-06-05 21:47:19

Oldfart1939,

If it wasn't fun to think about the possibilities, I wouldn't post here. That said, I'm also quite certain that Elon Musk doesn't take suggestions from the peanut gallery. If BFS tips over on Mars, then it doesn't matter how great a fuel LCH4 is. I just don't see how a ship that tall with the CG where it will inevitably be working well, or possibly at all, on anything other than a flat prepared surface. The Falcon boosters use aluminum crush tubes and land hard to "plant" the stage on the steel deck of a ship.

Since H2O or H2 is available pretty much everywhere humans could conceivable live, LH2 is the fuel of choice. If you can get N2, CO2, or other gases, then that's great, but for $26M, you can purchase the M400 and have your own H2 plant in a shipping container. It can fill the SLS main tank in about a year, even with losses from boil-off. At this point in time, H2 technologies are more mature than CH4 because we can simply pump the stuff out of the ground here on Earth.

Boeing's Orbital Propellant Depot:

LEO Propellant Depot: A Commercial Opportunity?

Roughly what I had in mind for BFS:

Thigiverse - kbpiper01 - SpaceX BFR

It's shorter and lighter, thus easier to land vertically. The loss of payload mass and volume is not a problem since the vehicle is not intended for long duration habitation and the required masses and volumes of equipment easily fit inside the smaller vehicle.

I intended for the vehicle to use a LOX/LH2 staged combustion base-bleed truncated annular aerospike engine fed by multiple turbopump assemblies to pump propellants into "Wheel of Fortune" style injector plate assemblies arranged in "slices" around the circumference of the engine, such that individual turbopump failures don't cause a complete loss of thrust. The engine has the ability to spin up and spin down pumps to provide varying levels of thrust at optimum Isp. Attitude control is provided by varying the supply of propellant to individual slices of the complete injector plate assembly, thus thrust, just like the XRS-2200 linear aerospike.

The intent is that BFS alone is capable of suborbital flights without the need for the booster and orbital flights with no payload in order to retrieve satellites and propellant depot components after refueling at the propellant depot. As previously stated, IVF eliminates the need for separate systems for electrical power, reaction control, and tank pressurization.

This is about what I had in mind for the ITV, minus the gigantic center section:

Art Station - Mac Rebisz - Blue Pelican and a Tesla

The center section consists of a 8.4m SLS LOX tank. The empty propellant tank will be outfitted with a docking port for BFS to transfer passengers, avionics and communications, life support, and a water tank around the inner diameter of the tank for solar flare radiation protection. A power and propulsion module that contains distilled water for the MPD thruster, solar arrays for power, and batteries will be attached to the other end. An inflatable ring with a 50m radius is attached to the primary module and the habitable portions of the spacecraft spin to provide artificial gravity. 50m is the length of the original SpaceX BFR and the artificial gravity section is inflatable to fit inside a BFS.

Oldfart1939 · 2018-06-05 22:36:55

I too, share concerns about the CG of the landing BFS. There need be some much wider, outrigger type stabilizers to keep from tipping over. Hopefully they will have a reality attack in the Texas test flight area and attempt some landings in the desert around McGregor--in their test range. Musk seems to have some sharp engineers working at SpaceX, so they may have some plans not yet revealed to us mere mortals.

kbd512 · 2018-06-05 23:07:16

Oldfart1939,

I'm sure SpaceX does have gifted engineers, but there's only so many engineering tricks that can be applied to overcome fundamental stability issues. The dynamic loads involved are pretty substantial. An empty BFS with a 150t payload weighs as much as three orbiters and even on Mars it weighs nearly 12t more than an orbiter.

If the vehicle was a bit shorter, gave up some payload and volume, and/or used wider landing gear, it'd work a whole lot better for rough field landings. Who knows, maybe someone from Boeing or Lockheed-Martin will read this and decide to build a better lander with the piles of cash they're sitting on. I'd love to see a real competition to speed things up a bit.

Oldfart1939 · 2018-06-05 23:12:02

kbd512-

I think the only "engineering trick" they can use is a wider span on the landing legs; bigger "footprint." Best way to avoid having a Musk Memorial Crater at the landing site.

Last edited by Oldfart1939 (2018-06-05 23:15:33)

RobertDyck · 2018-06-05 23:54:59

kbd512 wrote:

Who knows, maybe someone from Boeing or Lockheed-Martin will read this and decide to build a better lander with the piles of cash they're sitting on. I'd love to see a real competition to speed things up a bit.

Boeing and Lockheed-Martin have clearly said they don't intend to do squat unless NASA pays for it. The only reason Boeing is building CST-100 Starliner is NASA is paying for it through the Commercial Crew program. It isn't the traditional contract they're used to, but NASA is still paying. Lockheed-Martin is building Orion, which NASA is paying using a traditional contract.

You think they'll give up any of the cash they're sitting on? Say that to Smaug.

louis · 2018-06-06 00:54:18

What about a double pass landing?

I am not in a position to personally dispute your 11G figure but Space X's claim is that the forces will be 4-6 G (earth G) on entry to Mars and 2-3 G on return to Earth.

https://imgur.com/a/1uIdn

Oldfart1939 wrote:

Louis-
It's not what they are planning, but simply a consequence of a direct atmospheric re entry from Mars. This is not me blowing smoke--just the physics as stated by GW, elsewhere.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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