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For kbd512 ... just a quick note to acknowledge your long post #25, and your recent contribution to the asteroid harvesting series. The bolo example is interesting, and I hope it generates some interest.
I just looked in on the Dropbox account, and we have two files there, both from 2023.
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For kbd512 ....
Please see https://newmars.com/forums/viewtopic.ph … 68#p220468
I've set up an Azure account for the forum upgrade. If you can make tomorrow's Google meeting, we can (hopefully) try it out.
I created the account with a password that is designed with you in mind.
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For kbd512 ...
My experiments with the plain Apache we set up were less than rewarding ...
Everything I tried ended up with a decline. I sent you an email with a few of the details.
The environment is MUCH less accommodating than the ** real ** Ubuntu.
I think it makes sense to remove that instance (if we can) and try to set up the LAMP.
I'll check back to see if you want to work on this again this evening or later this week.
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Do you have time to work on the forums at 8PM CST?
If so, I'll be here.
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For kbd512 re #29
I just finished some chores and found your message.
I'll set up the Google Meeting and try to have it ready by 9 PM my time. I might be a minute or two late.
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Okay. I'll be there.
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tahanson43206,
My modified copy of the FluxBB Master has been uploaded to DropBox. Please let me know if you're able to access the files.
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For kbd512 re #32
Thanks for doing the upload! I pulled it down on the U64 where the database is already installed.
The file size shows as 380 kb ... file name is fluxbb-master.zip.
Does this go into the same folder/directory as the existing php files? I assume so but thought I'd check to be sure.
I vaguely recall that there is a pointer file in the apache2 chain that points to applications.
You saw the listtopic.php script running... it is installed in /var/www/html
There's a file called "require.php" located at the www level. OK ... that file provides access to the mysql database.
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tahanson43206,
The extracted files from the ZIP archive file are to be deployed into the "htdocs" folder / directory (or whatever directory your setup is pointed at / named, since this is configurable) of your Apache Web Server's installation directory.
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For kbd512 ...
Thank you for the detailed post about composite materials for rocket tanks compared to steel as used by SpaceX.
Here is a quote from your conclusion:
If I had to hazard a guess, Elon Musk (most likely) or someone else at SpaceX attempted to apply their observations about what happens to highly stressed COPVs at cryogenic temperatures to a CFRP main propellant tank that experiences nowhere near the stress of a CFRP COPV operated at the same temperature.
I'm wondering if you might be willing to add definitions of the abbreviations at the end of the document, for readers who might not be familiar with the subject?
It seems to me the overall point (in response to RGClark's questions) is made effectively.
In your conclusion, I confess to having lost track of the materials. I ** think ** the paragraph was comparing steel to composite, but am not sure.
***
Thanks for the guidance in #34 .... You have access to the test system in Azure, so you can set up the software properly there.
We have 12 days left in the free trial. Everything is working properly, as far as I can tell. The ssh command should work for you by just changing the IP address to the new value as published in the Azure topic.
The only wrinkle that may occur is authentication. Azure challenges me to provide a code from the newmarsmember gmail account when I use a different computer to access the system. If that happens I'll be happy to assist, but it may not because your computer may already have the hidden files that grant access.
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For kbd512
SpaceNut found a link to a backup of the missing newmars front page: https://web.archive.org/web/20190522184 … wmars.com/
The 404 error is still there.
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tahanson43206,
I have a copy of the page ready to go, if only I could log into the server.
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For kbd512....
Thanks for the update.
Let's email to consider next step.
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For kbd512 re post in Housekeeping!
Thanks for an excellent suggestion!
I'll schedule a work session to scan phpBB3 in the near future.
If I can fit it in today I'll do so, but I'll get to it Saturday for sure. Friday is booked.
I appreciate your support of phpBB3, because it is shaping up nicely in the Azure test account.
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For kbd512 re Registration message....
SpaceNut tried to change the registration message using Admin tools, but apparently there is no option to edit the text.
The text is located in the register.php file.
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For kbd512 re Steel for Trains post...
http://newmars.com/forums/viewtopic.php … 55#p222955
That post deserves recognition .. Thanks for collecting and showing all those examples of use of steel and coatings suitable for a Lunar railway.
Please start thinking about a Like feature we might add to the FluxBB package we are preparing for deployment.
What I have in mind would use the existing Integer Edited field in the Posts table. That field would be updated by a new class of membership, the LikePosts class, which would be offered to NewMars readers who do not want to move all the way to Registered membershipm, but would like to encourage NewMars authors.
The feature would require a new table with Post ID matched with User ID for a like, and only one "like" per post per user.
An Admin report would allow display of which users liked a given post.
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For kbd512 re analysis and discussion of staging of rockets to reach orbit, and propulsion concepts in general, in the SSTO topic.
I'd like to see a mathematical treatment of the problem at some point, with visual aids for non-mathematicians.
I'll try to come up with a chart form that might work as a frame for NewMars members to use to come to grips with the problem.
The problem (as I understand it) is that there are multiple variables involved in design of a rocket system able to reach orbit in a given gravitational field.
The variables include:
1) Mass of each stage (dry mass)
2) Mass of propellant for each stage
3) ISP of propellant in each stage
4) Design of the rocket engine and related hardware
There may be other variables.
As a first cut at developing a collection of knowledge, a chart might include a set of points representing each successful rocket design that has reached orbit.
The point might be located on the chart based upon mass at liftoff vs mass in orbit.
Color of each point might be determined by the number of stages. None of the points would show SSTO from Earth, but SSTO from the Moon has been demonstrated, and SSTO from Mars has been described by GW Johnson in multiple topics and in YouTube videos.
I am hoping to enlist the talent assembled in this forum to create a work product that will be useful to a wider audience.
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For kbd512 re analysis of SSTO based upon Shuttle external tank as a starting point...
I've added that post to the index for the topic in #2
If you have time, I'm wondering if you might be able to provide a summary of all that work at the bottom...
1) Would the design work?
2) How many passengers can be transported to LEO?
3) The goal is a reusable aircraft-like vehicle... can the vehicle you've described return from LEO?
I still think RGClark is on a wild goose chase, but he's stimulated thinking by members of the forum, and your support in particular seems encouraging.
Does your design have enough fuel left over for descent and landing?
A lifting body design might help with the return problem, but a burn is still needed to drop the vehicle out of LEO after the passengers exit.
Return of passengers to Earth may remain the domain of the TSTO designs. The risks are simply too great with that huge SSTO.
However, success with the SSTO for lifting passengers might provide the financial incentive to pursue it.
The huge vehicle you've described would seem to call for a large number of passengers to justify the investment.
Return to Earth in smaller TSTO vehicles would spread the risk, so that market seems assured.
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Shuttle tank was a throw away tank that did not stay with the shuttle as part of its dry mass.
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tahanson43206,
1. Engineering determines what does or does not fly, not opinions about what "looks reasonable". What is "reasonable" for metal aircraft with significnat secondary structures, especially heavy ones subjected to thousands vs hundreds of takeoffs and landings, higher limit g-loads, using higher safety factors than reusable orbital launch vehicles, is not the same as for composites.
A chapter from a book entitled "Solidification", by Hongfei Zheng, Xuesen Zeng, Jianbao Zhang and Hongjie Sun, primarily about the fabrication of cryo tanks by NASA, and covers many of the important aspects of fabrication:
The Application of Carbon Fiber Composites in Cryotank
This NTRS document is from 2013:
STRUCTURES AND DESIGN PHASE I SUMMARY FOR THE NASA COMPOSITE CRYOTANK TECHNOLOGY DEMONSTRATION PROJECT
Another NTRS document:
Design, Manufacture and Test of Cryotank Components
Note how thick plies were used to make the fabrication process faster. We're not worried about manufacturing speed. We want quality and low weight, which means thin plies and autoclaving, but less weight and very low porosity if you look at the pictures. Using composites to save money is one application of these materials, but this vehicle requires higher strength-to-weight performance. If it takes 2 weeks or even 3 weeks to lay the plies vs 1 week, who cares? We're not making expendable cryo tanks for SLS upper stages, and there's one or at most two operators babysitting the machine. NASA used T700 and T800 fibers. We're using T1100 fibers. There's a healthy increase in the tensile strength of the fibers and therefore the composite- 400ksi (T700 and T800) to 500ksi (T1100) is pretty significant. When NASA performed their testing, they achieved a 42.9% mass reduction over Al-2195 using weaker TorayCA T700 and T800 fibers. We're using significantly stronger T1100 fibers. We also have CNT and BNNT fibers that make T1100 look rather weak by way of comparison. All composite primary structure for rockets has been a series of baby steps. This is not a "giant leap", it's a comprehensive application of all the best technologies and practices into a single vehicle.
Speaking of composites, NASA is actively working on non-regeneratively cooled Reinforced Carbon-Carbon rocket engine nozzles with UHTC coatings that prevent very high temperature oxidation / erosion from the hot exhaust gases, and progress has been superb, meaning multiple successive firings with minimal erosion of the RCC's protective coatings with little to no cracking. The reason for this is simple- RCC nozzles are half to a third of the weight of Copper and Nickel or steel alloy regeneratively cooled metal nozzles, plus a significant decrease in engine complexity related to active nozzle cooling. If the only component regeneratively cooled is the throat, then you can save quite a bit of weight.
The military is starting to replace Titanium and high strength steel alloys with composite landing gear structural components, namely all the heavy steel drag braces, oleo strut fixtures, etc. For example, these components are incorporated into our F-16 fighter jets and various military helicopters, some of which have all CFRP-composite gear except for steel axle pins and bolts. We're going a step beyond, by implementing rubberized Aramid (Kevlar) fabric reinforced tracked gear with composites road wheels to save weight and greatly reduce ground pressure over heavier yet much lower contact surface area Nitrogen-filled rubber tires which are subject to bursting from over-speed landings or overpressure from heating. Using a little extra power to tow a tracked gear aircraft back to the hangar is not a big deal. Reducing ground pressure to a 1/3rd of what it would be with rubber tires, is a very big deal. In an emergency, this thing could land on a dry lake bed or a flat field, unlike virtually any airliner, because ground pressure is too high with rubber tires, so the wheels sink into the ground, and shear off, frequently flipping the vehicle. This is not something we want to make a habit of doing, but landing options are good to have when piloting a glider.
People keep pointing back at the X-33 as some sort of "proof" that composite propellant tanks or SSTOs are impossible. That was 30 years ago. Both engine and composites technology has moved far beyond what was achievable in the 1990s. It's time for people stuck in the past to move on as well. The composite propellant tank problems of the X-33 / VentureStar program have since been resolved in multiple different ways. If they were not, then there would not be expendable vehicles, and now partially reusable man-rated vehicles as well, routinely going into orbit with composite propellant tanks and other flight-critical structures such as landing gear on Falcon 9 boosters.
2. I want to seat, or more like "strap-in", 500 passengers.
I can only provide mass estimates for physically fit young adults. Most fit young women will weigh 50kg or less. Most fit young men will weigh 82kg or less. There are always outliers, but we're shipping pairs of fit young men and women. That means the nude weight of the pair of passengers is 132kg, and there will be 250 pairs, so 33,000kg in total. If I had 6 foot tall women, at 59kg, and 6 foot tall men, at 83kg, then 35,500kg. We're not taking obese people to Mars. For starters, they may not survive the ride to orbit. Secondly, someone who does not have the personal discipline to control the one thing the overwhelming majority of young adults have complete control over- how much food they eat and how much exercise they partake in, is not someone you want to spend the rest of your adult life inside a tin can with.
The Final Frontier Design pressure suit weighs 4.5kg, which equates to about 2,250kg for all 500 passengers.
A lightweight sealed O2 line equipped helmet (polycarbonate visor, BNNT composite shell, aerogel foam impact protection) will weigh about 0.5kg, so 250kg.
Soft booties (thick synthetic cushioning sock-like material with ankle protection and traction) will weigh about 0.5kg per pair, so another 250kg.
2L of water per passenger weighs 1,000kg. You'll be provided with 3 meals, at 1kg per person, another 500kg.
pax = passenger
35,500kg max pax + 2,250kg pax suits + 250kg pax helmets + 250kg pax boots + 1,000kg pax H2O + 500kg pax food. That means my payload, less seating, is 39,750kg. The "seating arrangements" are more like "strapping arrangements". Everyone is strapped in, on a floor / bulkhead, lying on their back on a pad, for both high g-tolerance and weight. They aren't taking anything else with them, because there's no room or weight to spare. Personal belongings will be delivered directly to their awaiting colonization ship using Starship cargo carriers.
3. Yes, the craft can return from orbit. It has a thermal protection system included in the mass estimate, but again, one made from modern lighter / stiffer / stronger / higher heat tolerance materials.
There's a lot of use of aerogel foams and woven BNNT fabrics on top, which is the material NASA is testing for heat shielding applications for reentry. The tiled bottom is TUFI, which protects from temperatures of up to 2,482°C and weighs 4.4lbs/ft^3, and of course, more aerogel foam, or felt actually, for bonding the tiles to the vehicle. Space Shuttle tiles were 12lbs/ft^3. Modern TUFI tiles, an improvement on Space Shuttle tiles, is what makes this possible, not belief. These tiles have already been flown aboard the X-37- a reusable military space plane. Similarly, the BNNT fabrics and aerogels have been tested in NASA's "blow-torch" tunnel, as I call it. These materials work, they can be used, and they have been extensively tested, as well as being the subject of active ongoing testing and refinement efforts.
We developed all these technologies, specifically for the applications we intend to use them for, so let's use everything we've fully developed.
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For kbd512 re SSTO 500 passenger transport...
That vision is a good companion/complement to Large Ship.
Could you use an entire forum to provide a framework?
SpaceNut is thinking about creating a new category for Projects.
He has experimented with the idea in the clone, where changes can be made without risk.
I understand you don't have time to read Housekeeping, so I'll just invite you to assist SpaceNut in thinking through what the new structure might look like.
I'm interested in seeing a gradual introduction of achievement into the NewMars history. We have GW Johnson's course material to count as a win, and we have Large Ship as a well established root, from which an entire forum could develop.
As a reminder, (mostly for NewMars members) the structure here is:
Category (like Meta New Mars)...
Forum (like Mars Society)
Topics without limit
Posts within topics again without limit
My proposal is:
Category: Projects
Forum: Large Ship
Topics: As many as are needed
Posts: As many as are needed
***
In your case (if you are interested)...
Project Category
Forum: SSTO 500 Passenger Transport
Topics: As many as are needed
Post within topics: As many as are need.
The structure ** should ** provide the framework needed to move from vision to fact in a series of steps
A 500 passenger transport would be a goal to be achieved.
A single passenger SSTO would be a step along the way.
To my knowledge (admittedly limited) there exists on Earth today NO such vehicle.
An organization intending to build one will necessarily be at the bleeding edge of human capability.
That means failure will occur, and it will take persistence and stamina to overcome failure.
A first step in the long sequence that would lead to a successful flight starts with the simple decision on how to structure the environment.
SpaceNut is thinking about the idea of creating a new Category for Projects.
What would it take to help SpaceNut to move from contemplation to action?
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Off the top of my head, this project has the following functional areas:
1. Primary Propulsion System
The turbo machinery will be based upon Raptor engine technology, with non-regeneratively cooled UHTC coated RCC nozzles to reduce engine weight and complexity. I would like to explore the idea of multiple Raptor power heads feeding into a single larger main combustion chamber, in order to further reduce weight and complexity, and to improve frontal thrust density (GW's point about solids vs liquids and why you always get more frontal thrust density from solids), while decreasing the size and weight of the thrust structure to the absolute minimum. We will use differential thrust in different sections of the combustion chamber for thrust vector control, rather than hydraulic or electro-hydraulic actuators to gimbal the nozzle or entire engine. That eliminates fuel-hydraulic TVC, further reducing weight and complexity.
RCC nozzle tech is being developed for LOX/LH2, LOX/RP1, and LOX/LCH4 engines, in addition to solid motors. The stated goal is to raise the temperature limit from 2,000F / 1,093C to 4,000F / 2,204C, with the possibility of going beyond that using UHTCs that protect the RCC from high temperature oxidation / spallation / erosion / etc. The UHTC coatings have been plasma sprayed onto the nozzles, using materials such as Zirconium-DiBoride / Hafnium Carbide / Silicon-Carbide, amongst various highly refractory coatings.
Imagine if you had the turbopumps from 2 or more rocket engines feeding into a single combustion chamber, and instead of using gimbals and fuel-draulic actuators to vector thrust from the engine by gimbal, you instead varied the throttle setting on one or both engines to effect thrust vector control. The Soviets had 1 set of turbopumps feed multiple combustion chambers because they never solved combustion instability for higher thrust engines. This is the opposite. We have multiple engines feeding propellant into a much larger combustion chamber. The "power head" is the combination of both sets of turbopumps, so-named because that's where the pumping power to force-feed propellant into the combustion chamber is coming from.
The ultimate propulsion system design goal is development and testing of a non-regeneratively cooled high temperature ceramic composite expansion-deflection nozzle system using multiple Raptor power heads to feed propellants into a reduced number of combustion chambers, enabling a stationary engine and nozzle arrangement to provide thrust vectoring control without the movement of engine components.
2. On-Orbit Maneuvering Propulsion System
RCS will be based upon gaseous O2/CH4 residual propellant to power the maneuvering thrusters. This RCS is non-standard, but we're using leftover gaseous propellant from the main tanks rather than carrying the weight and equipment associated with a completely separate RCS solution burning lower-Isp storable propellants. Ullage is normally 1% to 3% of what you loaded, so there is more than enough residual propellant for on-orbit maneuvering and the de-orbit burn. Much like the main propulsion system, RCS will be tightly integrated into the vehicle as a whole.
3. Airframe / primary structures
This is a substantial analysis and development task unto itself.
T1100 fiber is our structural material of choice, because it is presently used to construct cryogenic propellant tanks for smaller rockets, high pressure H2 and CNG storage vessels, and other similarly demanding applications.
PBO / Zylon fiber honeycomb and aerogel foam insulation will provide the core material / insulation between the inner and outer tank wall, as well as greatly increasing stiffness / rigidity (from increasing the thickness of the composite). Imagine, for example, the difference in stiffness between the 1/8th inch thickness of Al-2195 of the Space Shuttle External Tank and a half-inch thick composite. It's not 8X as rigid, it's 32X stiffer as well as substantially stronger. That's the difference between a cheaper disposable metal tank and a reusable tank.
Graphene flake or short / "chopped" CNT additive will be mixed into the resin to form a 3D bond between the other fibers and the resin matrix. Graphene flake has been shown to form or contribute to the formation of an impermeable membrane preventing the escape of H2 through the matrix. CNT has been used to decrease the weight of high pressure O2 and LOX tanks by up to 75%, simply by locking the fibers and matrix together. In our case, we're after more strength for a given weight, rather than less total weight.
Although BNNT and CNT fibers are now being produced in multi-hundred to multi-thousand ton quantities per year, all-BNNT and all-CNT composites are unknown quantities, and not certified for aerospace applications. While these materials are now accepted as composite resin matrix additives for O2 and H2 resistance and bond strength improvement, they cannot be used as the primary structural fiber until certified as aerospace materials for composite applications. T1100 and RCC composites are both certified aerospace fiber- same fiber with a plastic vs ceramic matrix. T1100 filament wound composites are vacuum bagged and autoclaved. RCC is made by putting the composite layup in a vacuum furnace so the fiber doesn't sublimate away while the ceramic fuses the fibers together. BNNT will receive certification as a heat shielding material, but not as the fiber in a composite. Similarly, TUFI tiles now used on operational aerospace planes use aerogel to prevent heat transfer. CNT has been used in composites, but material properties are still under investigation. As I understand the problem with certification of CNT fiber, which is 8X to 9X stronger than T1100 fiber and does not "break like glass", obtaining BNNT and CNT fiber with uniform strength, length, and diameter remains problematic. Uniformity matters. There are some solutions on the horizon, but until that time comes, T1100 is the best fiber we have. T1100 fiber specifications are very rigid, just like the fiber itself.
4. Landing Gear
This is likely a tracked system to reduce ground pressure and weight, so composite struts, drag braces, etc, and I think the road wheel axles, oleo pistons, and fasteners will be high strength steel. The tracks will be contain Kevlar or Zylon or some similar high tenacity fiber, rather than steel. If it's not apparent by now, this SSTO vehicle will be a "Master Class" in composite materials and integrated design.
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(continued)
5. Aerodynamics and load modeling
These tasks will be broken down into propellant fill / drain operation and thermal-mechanical effects on the composite structure and attached thermal protection system, ascent aero and thermal loads- design for a specified maximum dynamic pressure and acceptable heating, on orbit thermal loads from onboard systems and passengers, reentry aero and thermal loads, landing loads, the loads applied to the control surfaces, and launch related loads- we can't forget those.
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6. Life Support and Auxiliary Systems
This consists of atmospheric scrubbing, waste water recycling or removal- probably just removal, cabin thermal management which is a significant issue with 500 passengers (perhaps extendable CNT fiber loop for radiative on-orbit waste heat removal), extendable thin film photovoltaic array for on-orbit power, an APU to power flight control surfaces- likely also consuming gaseous / waste O2/CH4 from the main tanks.
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7. Cockpit Design, Naviation, Sensors, and Communications
Our cockpit instrumentation will be "all-glass" to reduce weight. Sensors for precision navigation will include FLIR and/or imaging radar for all-weather precision approach and landing. A laser ring gyro is required for initial internal guidance. GPS will provide primary spatial positioning / navigation, with cross-reference to a backup star tracker. Communications will consist of SHF satcom SDR radios, similar to what NASA already uses for CAPCOM. Internal crew communications will be based on wifi or bluetooth or both.
8. Airframe and Engines Maintenance and Inspection Program
Having a rock solid composites and TPS inspection and repair program will rapidly become of extreme importance for highly stressed orbital launch vehicles, plus maintaining all the crew life support equipment. We do need atmospheric recycling / revitalization. We don't need waste water recycling. The engines require routine tear-down inspections and cleaning, because even CH4 leaves a little bit of soot- not nearly as much compared to RP1, but cleaning is still required, for inspection if for no other reason.
9. Routine Flight Operations
The service provided will somewhat resemble an airline service run by the military. Everyone aboard is a trained crewman, out of necessity, but not necessarily an expert in every aspect of flight operations. For example, I don't need to tell someone in the military what CPR is or how to perform it, because we all receive routine training for this. I don't need to tell them how to clean something, because we all do this. We have manuals and procedures that tell us how to take equipment apart, how to inspect it, and if / how we can repair it vs sending it back to the factory.
I expect that there will be two people in a control tower who grant launch authorization, sort of like ATC, after deconflicting the airspace, and then the passengers aboard act as their own "Mission Control" to perform vehicle check-out / determination of readiness for flight, just as they will be for the rest of their lives on Mars. The people back on Earth are for development level technical support only. Certain passengers will be responsible for monitoring communications and relaying information, others will be assigned to keep an eye on engine vital signs, while still others are devoted to checklists and procedures, or life support systems monitoring.
The pilots up front are doing the flying, but since we have the people power to spare, everyone aboard is an active participant. There is no more, "That's not my job!" All that nonsense ends the moment you sign on to the Mars Colonization Program. You're in control, you're "making it happen", and you are directly and personally responsible for your own fate- life or death, but make the decision and do it quickly. We will provide the training, in the same way that the US Navy provides ratings to enlisted personnel, but then it's up to the men and women aboard the ship to "run the show". The big show starts with delivery of cargo to the colonization ship, this SSTO delivers each crew to their ship, the crew makes their way to Mars aboard their colonization ship under their own recognizance, and then they're responsible for running operations on Mars.
We need Airframe Structural Mechanics, Avionics Electricians, Communications Specialists, Gas Turbine Engine Technicians, Life Support Equipment Specialists, and so on. You can do all that stuff without a training program. The military trains people to do all of that and more, because they have to, so this program will be modeled on their programs, because their maintenance and repair programs are successful, long-established, and the "rules of the road", such as it were, are all based upon hard-won experience. The experience gained from helping to maintain their SSTO, will then be applied to maintaining the colonization ship, and finally, to maintaining the equipment that makes life possible on Mars.
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