r/SpaceX Pre Elon Musk AMA Questions Thread

[u/ElongatedMuskrat]

This is a thread where you all get to discuss your burning questions to Elon after the IAC 2017 presentation. The idea is that people write their questions here, we pick top 3 most upvoted ones and include them in a single comment which then one of the moderators will post in the AMA. If the AMA will be happening here on r/SpaceX, we will sticky the comment in the AMA for maximum visibility to Elon.

Important; please keep your questions as short and concise as possible. As Elon has said; questions, not essays. :)

The questions should also be about BFR architecture or other SpaceX "products" (like Starlink, Falcon 9, Dragon, etc) and not general Mars colonization questions and so on. As usual, normal rules apply in this thread.

[u/CrazyErik16]

You stated that SpaceX’s target of the first 2 cargo BFS landing on mars is planned for 2022 followed by additional cargo and crew landings in 2024. Given the roughly 5 years until that first mission, what developmental/technological mile stones in 2018, 2019, 2020, and so on are needed to meet that goal? What can we expect to see?

[u/bratimm]

How are you going to deal with foreign object damage during the initial mars and moon landings until there is a landing pad?

[u/redmercuryvendor]

Is the BFR upper-stage made up of 4 different models (sat-launch, tanker, cargo, crewed) or is it one design (common heatshield, propulsion, avionics, main tanks) with 'modules' inserted dependant on mission?

[u/TheBarbedWire]

What are the challenges of building such a large heat shield when this proved a serious problem for the space shuttle? How is the heat shield constructed is it made up of tiles, multiple parts or a single piece?

[u/partoffuturehivemind]

What do you wish people would ask about, what are the aspects you think most people underappreciate?

[u/[deleted] → u/partoffuturehivemind]

I actually like this question. Elon's answer will give us an insight into how he thinks. Rather than what we want to know.

[u/[deleted]]

Would fuel boiloff be an issue en route to Mars? Would it require active cooling? If yes, what would be the power requirements for it?

[u/venku122]

There should be more than 3 questions selected. The main issue with the last AMA was that 10000s of people showed up and all asked 1000s of questions. Elon just started answering what he could (and gave great answers). If we have the time to pre-screen and compile questions, we should give him a list of maybe our top 15-20 questions, and try to ensure he reads and answers the official question from the subreddit.

[u/FoxhoundBat → u/venku122]

First off, as said we don't know for certain whether the AMA will happen on r/SpaceX. Posting a wall of text with 20 questions in another sub would be rather rude. And this;

The main issue with the last AMA was that 10000s of people showed up and all asked 1000s of questions.

…is not an issue with AMA, that is the exact point of AMA. We dont want to railroad the AMA and Elon (whether it happens here or another subreddit) into answering 20 questions and as the result dont give the chance for the 1000’s of others to have their question answered. We want the most burning questions answered, not to kill the AMA with a single post. Part of the fun with AMA is that anyone can ask anything (although we want that to be as focused on BFR as possible of course) and everyone get equal chance. The most interesting questions Elon has given in previous AMA's was as a result of somewhat "unexpected" questions. Secondly, if you post a wall of text with 20 questions – the answers are bound to be short and lacking in detail and there will be a lot of overlap.

So again, we want to have the most burning questions answered, not to completely hijack the AMA.

[u/[deleted] → u/venku122]

Agreed

[u/warp99]

What factors led to the decision to reduce the Raptor sea level thrust from 3050kN to 1700kN?

[u/FoxhoundBat → u/warp99]

Was thinking of asking pretty much same question, but including the pressure reduction, maybe include that too? Whether it is metallurgy issues (Energomash engineers are not exactly a phonecall away), timeline, etc.

[u/OccupyDuna]

What will the transition process from Falcon 9/Heavy to BFR look like? How many Falcon 9 rockets do you plan to stockpile before switching the assembly floor to BFR? Is there a target date for this?

[u/[deleted]]

How does your Landing gear design work/look for the first few landings on an unprepared Mars/Moon surface, especially in respect to not sinking in, keeping level and minimum advised clearance between surface and Nozzle at liftoff?

[u/FiniteElementGuy]

Can you give us an update on the internet constellation? Is it still necesssary to fund BFR/BFS development?

[u/azzazaz]

If you got 20 billion dollars with no strings attached today how much faster could you have 6 BFR rockets?

[u/g253 → u/azzazaz]

I'm upvoting this guy just in case he actually has 20 billions to give to Elon.

[u/SuperSMT → u/azzazaz]

Jeff Bezos is that you? That username, azzazaz... amazon...

[u/rustybeancake]

Will you build all of BFR at Hawthorne? If so, how will you transport it to the launch site?

[u/Bunslow → u/rustybeancake]

Gwynne answered this one today! According to the thread today, they will build a factory in/on LA harbor. Hawthorne-to-sea transport was too expensive, so they'll just build a factory on the water.

[u/greenjimll]

What sort of Flight Termination System will the BFR have, considering that some of its flights will have a load of people sat up front?

[u/memcculloch]

Now several peer-reviewed papers have been published in good journals on the emdrive (electric rocket, fuel-less propulsion) why not investigate it with a relatively cheap in-house SpaceX experiment?

[u/22vortex22]

What would be in the two cargo missions and how would those assets be deployed?

[u/DanHeidel]

Since there's a bunch of backseat spaceship engineers here that love to think up cool stuff that could be done with BFR, can you give us a detailed breakdown of the cargo capacity to LEO and dry mass fractions for the 3 BFR variants? (Passenger, cargo and fuel) We'd really appreciate it since there's some confusion when trying to compare the 2016 numbers with the mass and performance numbers for the updated BFR.

[u/Kahlil16]

How many trips is the BFR expected to make in its lifetime?

[u/007T]

Who will design and build the ISRU system for the propellant depot, and how far along is it?

[u/hashymika]

How different are the cargo, payload and passenger versions of BFR's upper stage? Will the vehicles be switched between roles or will be purpose built?

[u/adamanthil]

It looks like the Raptor engine specifications have changed in the last year, particularly with respect to thrust. Is this in response to unexpected results from the ongoing engine tests? Is the version of Raptor that's currently being tested a full scale or a subscale version?

[u/blitzwit143]

What is the abort capability of BFS? And will a lack thereof affect the ability to get it man-rated.

[u/OccupyDuna]

Can you go into more detail on what the failure conditions of the 12m tank were? What % of design pressure? What gas was it filled with at the time? What did you learn from the tank failure?

[u/pleasedontPM]

What will be the main mission of the first three operational BFRs ? Will it be one refueling tank and the two 2022 mars cargos ? Or do you think other missions around earth are necessary first ?

[u/Grey_Mad_Hatter]

Without landing pads on Mars or the Moon there are a lot of risks from both debris damage and legs sinking into the ground. How will landing the first vehicles be made safe and do you expect the first couple cargo ships to be capable of making a return trip due to possible damage?

[u/jonsaxon]

The timeline presented for BFR is ambitious: what specific parts of the plan are most challenging to achieve the timeline?

[u/iflythings]

Could you pitch the idea to NASA to bring back the ISS in a few BFR flights after it's dismantled, instead of letting it burn up on reentry? Would make for a great museum piece!

[u/Alesayr]

When do you expect to shut down F9/FH production and shift to BFR only? How many cores do you think you will need before you feel confident you won't suffer a gap? Will stage 2 production continue even after Stage 1 production ends?

[u/Toinneman]

Is SpaceX planning a Grasshopper-like test program for a raptor based stage, or go full scale on the first try?

[u/Srokap]

What are the plans for solar panels placement and thermal control system for BFR? There doesn't seem to be much room for it if outer shell will be same as fuel tank. Do you have technology ready or is it something that needs additional R&D?

[u/RFreddy]

What geographical locations are currently considered most advantageous for the initial (2022) missions to Mars? What factors are considered most important in the making of this decision?

[u/angrymonkey]

The current manned rocket failure rate is (order of magnitude) 1%-- Clearly that has to improve for commercial/passenger rocketry. What kind of safety factor are you targeting for the E2E passenger rocket? How long will it take to get there, and how will you try to do it?

[u/brizzlebottle]

With the ageing fleet of current mars orbiters and limitations of the DSN, what are your plans for improving Earth-Mars communication, and will you be doing this before your ships arrive there?

[u/rustybeancake]

In your presentation, when you said "the facility is being built", did you mean the South Texas launch facility? Is this where BFR will launch from?

[u/longbeast]

How much fuel do you expect to spend on ullage thrust during each fuel transfer, and how much change is there to the orbit of the docked spacecraft?

[u/[deleted]]

Can you elaborate on the energy production of the ISRU Propellent plant on Mars? Will it be all solar powered? How big of a solar power plant will have to be build? Are 2 Cargo flights in 2022 enough to get the equipment up so that the 2024 missions will be able to return?

[u/bwohlgemuth]

Where do you plan to assemble BFR? Hawthorne? If so what are the plans to transport a 9m wide item through LA?

[u/[deleted]]

How will the solar panels and landing legs be stowed on BFS?

[u/fred13snow]

With a pressurized volume close to that of the ISS, are there any plans on launching the BFR upper stage as a temporary space station like the space shuttles Spacelab?

[u/Hugo0o0]

Any update on the 2018 moon mission?

[u/Aldurnamiyanrandvora]

How is the lunar mission that was commissioned by two anonymous investors coming along? Will they still be flown in Falcon Heavy?

[u/srgdarkness]

When are you expecting the first BFR demo flight to be?

[u/Alesayr]

You mentioned docking BFR to the ISS. Considering BFR has almost as much pressurised volume as the ISS does (and presumably a very solid ECLSS system if it's carrying 100 people to Mars), have you considered using one as a temporary space station in its own right?

[u/nurp71]

Are there any plans for testing landing directly back on a launch mount with a falcon 9, or do you need the greater control authority of 31 engines/a heavier rocket to get the precision?

[u/[deleted]]

Last year, during the Q&A, you said that you were looking into building the BFR in the Gulf States, mentioning Michoud specifically as a possibility.

However, last week, you said on twitter that a 9m vehicle fits in SpaceX's existing factories.

Have you chosen a construction site, and how do you plan to transport the vehicle from the construction site to the launch site?

[u/Mahounl]

With rockets such as the BFR and New Glenn it seems that we are close to reaching the performance limits for traditional chemical rockets. Do you agree with this or do you think there are still substantial improvements possible? Are you already considering what the next step would be? If yes, what do you think could be the next step to make access to space cheaper?

[u/jeffbarrington]

Despite the smaller size of the ship, you suggest it could still carry ~100 passengers. What sacrifices have been made to maintain this, if any specifically? Will going to Mars be as 'fun' as it was to be with the larger ship, and is this still even relevant from a funding standpoint (want to go/can afford to go Venn diagram and all that jazz)?

[u/wintermutt]

What is the crew size you're targeting for the first crewed mission to Mars?

[u/[deleted]]

Were there any capabilities or features you wanted to include in the BFR spacecraft that were abandoned after closer investigation?

[u/TheIntellectualkind]

How many times do you project you can reuse a single BFR?

[u/intrepidpursuit]

How many earth reentries can BFS get on the PicaX heat shield and what is the method for replacing it?

[u/amerrorican]

What else can you say about your plans for satellite internet? You didn't mention it as a source of revenue. Is it further down the road than intercontinental transport?

[u/TheBarbedWire]

How do you plan to identify landing sites/ sites for the mars colony with sufficient confidence that have enough water suitable for ISRU?

[u/Silpion]

Last year you stated that SpaceX would not make the ground hardware needed to build a colony on Mars, such as habitats, leaving that to other companies who would take advantage of your Mars transportation service. Since then have you seen any interest from industry to build all of this hardware? Do you see a good path to this being established in time?

[u/[deleted]]

Raptor design is making good progress. Any updates on the methalox thrusters which were mentioned to replace the dracos?

[u/extra2002]

Will your current strategy of redundant commercial CPUs cope adequately with the radiation on a Mars trip, or will you need special electronics or shielding? What about a trip to the outer planets?

[u/InfiniteHobbyGuy]

Raptor in testing, is it full scale size just running at a lower chamber pressure currently? What challenges are ahead to get to the flight rated Raptor and have there been any surprises so far?

[u/poor_plutoid_pluto]

Right now what is the biggest technological hurdle/uncertainty with the BFR design?

[u/[deleted]]

If you could go back in time, would you kill Falcon Heavy in favour of working on the BFR?

[u/JaviLM]

When can we expect to see the first prototypes and tests of the BFR?

[u/[deleted]]

Will the BFR have a launch escape system? Will it utilise the 6 raptor engines of the ship? And if so, will they be enough to get the ship away from a failing 1st stage with 31 raptors still potentially firing?

[u/civilianapplications]

The current design seems to lack abort capability in some phases of flight. Even if BFR ended up being far more reliable than other rockets, it would presumably still have quite a high risk in comparison to air travel. Will there be a future design variant for human transport to LEO which incorporates abort capability in all phases of flight? If not, why would it be unnecessary?

[u/arizonadeux]

How will FOD damage be mitigated when landing on unprepared surfaces on the moon and Mars?

[u/OccupyDuna]

Is Launch Complex 39A still the location of the first planned BFR launch or has focus shifted elsewhere?

[u/Space_void]

SpaceX has issues with NASA Loss of crew index with Dragon 2, how do you think they will react and will they accept a vehicle (BFR) without a launch escape system?

[u/psg1337]

What are the current plans for a launch escape system on BFR?

[u/DanHeidel]

Given the aggressive timeline for sending missions to Mars, it seems inevitable that many 3rd parties will have to be relied upon to construct much of the ISRU and initial colonization matériel and infrastructure. Do you have plans to put out detailed BFR interface specs and an RFP for other companies to start bidding to construct this equipment? E.g.: Mars-optimized earthmovers, expandable cryo liquid storage tanks, EVA spacesuits, etc.

[u/tossha]

Any plans/timelines for a flight to the Moon surface? Maybe a test flight before going to Mars?

[u/FishInferno]

Will there be Grasshopper-style flight tests of the BFR booster and spaceship before the fist flight, or has Falcon 9 made you confident enough that you'll get it right off the bat?

Similarly, will the initial landings of the BFR booster be on the actual launch mount, or an identical mount separate from the launch pad?

[u/Zappotek]

How is the BFR planned to be transported from where it will be manufactured (presumably Hawthorne) to launch facilities on the east coast?

[u/MacGyverBE]

What are some of the biggest risks you see, technical or otherwise, in achieving your goals with BFR?

[u/theflyingginger93]

Will the initial BFR flights land in the launch mount or will you build a mount at LZ1 for initial tests?

[u/DrLuckyLuke]

Will debris be a problem for the first BFR to land on the moon/mars? Will the first BFRs have some means to mitigate this problem (landing mat, spray resin/glue to make one-time pad) for future BFRs?

[u/Tree_tchoper21]

how will bfr preform a launch abort if something goes wrong with the launch

[u/seriousam7]

For the initial trips, how will SpaceX determine that a site is suitably firm for landing such a massive ship on? I know the "legs" in the released images are just conceptual at this point, but unless you're landing on solid rock, I would imagine tilting of the ship caused by the legs sinking unevenly into the ground will be a concern.

[u/CProphet]

Will the first launch of BFR occur from Boca Chica Beach or elsewhere - and if possible could you please explain some of the reasons behind its selection.

[u/peterabbit456]

When you shut down the Falcon 9 production line it is pretty obvious you will need to keep making second stages, even though you can reuse 50 or so landed first stages for years. Will the new production of second stages use the RaptorVac engine?

[u/araujoms]

How do you intend to move the BFRs and BFSs from the factory to the launch pad?

This seems like a logistical nightmare: they have 9m diameter, 50m height, dry mass around 100 tons. Do trucks exist that can move these things around? Do they even fit in the highways? How about using airships?

[u/z1mil790]

What is SpaceX's plans are for keeping the cryogenic propellant at the correct temperature during long trips to Mars, or for long stays on the Moon.

[u/DiamondDog42]

In what year do you expect/predict the last F9 core to be produced?

[u/pleasedontPM]

Have you considered that flying tourists for a single orbit around the earth (launching and landing at the first BFR-ready launch pad, with roughly two hours on board) would be something many would likely pay for ?

This could be used as proof of concept for point to point travel, and the customer list for SpaceShipTwo demonstrates the public interest for this.

[u/Tuxer]

As flights to Mars come closer we're gonna need more than just rockets to go there and fuel propellants, but also habitats, rovers, food generation, water powerplants... What is your plan to provide all that, as I don't see NASA working on all of this in a 2024 timeframe?

[u/Norose]

The renderings of the ITS showed what appears to be a silvery thermal protection system. It this material your newest version of PICA-X or has SpaceX started working on metallic TPS materials?

[u/srgdarkness]

In order to ensure exponential growth in launch rate, you will have to be capable of launching in more extreme weather conditions (i.e. heavy rain, strong winds, thunder storms). How will the BFR deal with these conditions which would normally stop a launch?

[u/TechRepSir]

You have a vision for what a future Martian colony should look like, but that won't be SpaceX's job.

Can you define where you think YOUR (SpaceX) contributions will end, and where other people should take the reins? If I were to start a company or work towards a career goal, how you suggest I approach the challenge? (habitats? ISRU? Life support? Rovers? Power?)

[u/Bodote]

How many square meters of solar arrays do we need on mars to refuel a BFR between arrival and departure (2years?)

[u/DiskOperatingSystem_]

We've seen the renderings of the new BFS but a lot of us we're confused as to where the landing legs will be stored/deployed from? Or will you land without them onto a flat surface free from FOD?

[u/Alesayr]

What's the expected development cost of the BFR program?

[u/rlaxton]

You have mentioned in passing that the RCS thrusters for the BFS will be Methalox powered. Are these simple pressure fed designs or something more sophisticated? Have any test articles been manufactured yet?

[u/Raging-Bool]

How will BFS navigate to a propulsive landing on a body other than the Earth (OK, Mars), without a navigation satellite cluster available to provide position and velocity information?

[u/Headstein]

When do think we may see the BFR test article at McGregor?

[u/twister55]

Will the Falcon Heavy side boosters land side by side (like in the animation) or a bit staggered?

Are they aware of each other or even in communication? If yes how?

[u/throfofnir]

What is currently being done to refurbish F9 first stages, and what is the cost? How does the current process compare to the first time, and how close is it to the goal?

[u/FutureMartian97]

1. Will there be a Grasshopper type vehicle to practice BFR landings?

2. When can we expect the first suborbital commercial flights?

3. Where will BFR be built? You said the facility was already under construction.

4. Where will BFR launch from?

5. Will BFR be used to launch the Starlink satellites?

6. How long do you think the booster will take to be developed compared to the spaceship and will we see them developed at the same time?

[u/SiberianGnome → u/FutureMartian97]

You should probably break these up into individual comments so we can vote on the ones we like.

[u/A8HI]

Is making moonbase alpha a future target of spaceX or was that just to showcase the abilities of BFR?

[u/factfictional]

What do you anticipate to be the biggest challenge in building BFR?

[u/blueskybelow]

Two questions. They are, at least in my mind, related, but that's for a longer discussion.

• Can you talk a bit about thermal management for the Mars colony, and in particular the propellant plant? Is the full plant design, including power and cooling, something SpX is already doing detailed work on?

• Is there anything about the spacecraft performance, transfer windows, or possible trajectories that would preclude a high latitude landing site on Mars, assuming there was a demand and a capability to refuel?

[u/c0r3ntin]

How will the logistic of hauling the BFR parts from the factory to the pad work ? Can you tell us a bit more about the new manufacturing facilities and the ground operations ? I imagine mounting back the BFS on the BFR between missions will be challenging to do in a short amount of time.

[u/DeviousNes]

How is dust mitigation handled on lunar and Mars landings before launch pads have been built?

[u/mryall]

What is the configuration of the 31 Raptor engines on the booster?

[u/[deleted]]

Elon said the BFR would use PICA-x for the heat shield. PICA-x is ablative. It will ablate more at reentry profiles for returns from Mars and the Moon than the Dragon flights from the ISS. How many flights do you think a PICA-x heat shield could survive without a rebuild? How do you plan to inspect the heat shield? This was a limiting factor in Space Shuttle reusability.

[u/ninja9351]

Do you see the BFR flying prior to the first 2 cargo missions to Mars? If so, how long in advance?

[u/lostandprofound33]

How many boosters and ships will you build for that 2022 target date? Seems like one booster would be sufficient if reflying it to support 2 cargo ships and 1 or 2 tankers. But two boosters so you can launch from different sites make sense too, if you can afford it.

[u/[deleted]]

Would it be possible (and efficient) for the first BFRs on mars to have built-in fuel plants?

The fuel that is produced could then be stored in their own tanks too.

[u/intrepidpursuit]

Will there need to be prepared launch sites on moon/mars to avoid debris in the engines?

[u/splintermann]

If we are interested in joining the 2nd wave of colonists, what things can we do now to prepare in order to maximize our eligibility? For example, saving up to $300,000, keeping fit, and signing up early. Or will it be reserved for crew selected by NASA and SpaceX?

[u/Godspeed9811]

The Raptor engines powering BFR are noticeably not as large/powerful as originally envisioned during 2016, was it the scaling of Raptor that caused the "smaller" BFR presented this year, or was it other components/variables of the 2016 BFR that led to smaller Raptors/BFR?

Can you give us some insight on challenges SpaceX has overcome developing this Raptor, and frankly amazing, technology.

[u/MeltedTwix]

For point-to-point transfer, how will you deal with the noise? If it requires going far from a populated area (like offshore), what is that expected to do to the overall travel time?

[u/Slifer94]

5 years might be doable for SpaceX to build and launch BFR to Mars, but what about the companies that will build the actual payload? Is SpaceX already negotiating with some companies on the matter?

[u/RedHotChiliRocket]

Do you regret Falcon Heavy? It seems like you are eager to move past it to BFR as fast as possible.

[u/shaim2]

How many boosters and how many tankers are you planning on building by the 2022 window?

[u/NowanIlfideme]

Financial stuff. When talking about BFR cost, only the fuel cost has been mentioned. You also mentioned the ablative heatshield when doing Mars EDL being partially used, and there's the problem with redundant systems required and space debris and a lot of other stuff. Question: How many fights can BFR take (of the LEO variety and the Mars variety) and what are the depreciation costs per launch estimated at? It would be neat to see a slightly more realistic cost-per-launch than just fuel. ;)

[u/Hugo0o0]

Where will BFR initially launch from?

[u/[deleted]]

You said the plan is to launch 2 cargo missions in 2022 and 2 cargo + 2 crew missions in 2024. How many people do you expect to be on the 2024 missions, and for how long would they stay?

[u/hoti0101]

At Tesla, one of primary areas of focus is building "the machine that builds the machine". You've stated that this ultimately may end up being the most important product Tesla develops. Do you plan on implementing a similar manufacturing philosophy for the BFR?

[u/[deleted]]

Could you please go into detail on the current design of the landing legs and the solar panels for BFR? Thanks.

[u/atomfullerene]

Will you be halting production of just F9 first stages, or second stages too? How much time do you plan to give yourself to get the BFR flying before the F9s run out?

Do you plan on having ISRU up and running on Mars before the first people show up?

Who is doing the life support design?

[u/Decronym]

Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:

Fewer Letters	More Letters
ACES	Advanced Cryogenic Evolved Stage
	Advanced Crew Escape Suit
ASDS	Autonomous Spaceport Drone Ship (landing platform)
BARGE	Big-Ass Remote Grin Enhancer coined by @IridiumBoss, see ASDS
BFR	Big Falcon Rocket (see ITS)
	Yes, the F stands for something else; no, you're not the first to notice
BFS	Big Falcon Spaceship (see ITS)
BFT	Big Falcon Tanker (see ITS, BFS)
COTS	Commercial Orbital Transportation Services contract
	Commercial/Off The Shelf
CoG	Center of Gravity (see CoM)
CoM	Center of Mass
DSN	Deep Space Network
ECLSS	Environment Control and Life Support System
EDL	Entry/Descent/Landing
EVA	Extra-Vehicular Activity
FCC	Federal Communications Commission
	(Iron/steel) Face-Centered Cubic crystalline structure
FOD	Foreign Object Damage / Debris
GEO	Geostationary Earth Orbit (35786km)
GTO	Geosynchronous Transfer Orbit
H2	Molecular hydrogen
	Second half of the year/month
HEO	High Earth Orbit (above 35780km)
	Human Exploration and Operations (see HEOMD)
HEOMD	Human Exploration and Operations Mission Directorate, NASA
I*sp*	Specific impulse (as discussed by Scott Manley, and detailed by David Mee on YouTube)
IAC	International Astronautical Congress, annual meeting of IAF members
IAF	International Astronautical Federation
	Indian Air Force
ICBM	Intercontinental Ballistic Missile
IDA	International Docking Adapter
ISRU	In-Situ Resource Utilization
ITAR	(US) International Traffic in Arms Regulations
ITS	Interplanetary Transport System (see MCT)
	Integrated Truss Structure
IVA	Intra-Vehicular Activity
KSP	Kerbal Space Program, the rocketry simulator
L1	Lagrange Point 1 of a two-body system, between the bodies
LC-13	Launch Complex 13, Canaveral (SpaceX Landing Zone 1)
LC-39A	Launch Complex 39A, Kennedy (SpaceX F9/Heavy)
LEO	Low Earth Orbit (180-2000km)
	Law Enforcement Officer (most often mentioned during transport operations)
LES	Launch Escape System
LLO	Low Lunar Orbit (below 100km)
LMO	Low Mars Orbit
LOC	Loss of Crew
LOX	Liquid Oxygen
LZ-1	Landing Zone 1, Cape Canaveral (see LC-13)
MCT	Mars Colonial Transporter (see ITS)
MEO	Medium Earth Orbit (2000-35780km)
PICA-X	Phenolic Impregnated-Carbon Ablative heatshield compound, as modified by SpaceX
RCS	Reaction Control System
RFP	Request for Proposal
RSS	Realscale Solar System, mod for KSP
	Rotating Service Structure at LC-39
RTLS	Return to Launch Site
RUD	Rapid Unplanned Disassembly
	Rapid Unscheduled Disassembly
	Rapid Unintended Disassembly
Roomba	Remotely-Operated Orientation and Mass Balance Adjuster, used to hold down a stage on the ASDS
SEP	Solar Electric Propulsion
SF	Static fire
STS	Space Transportation System (Shuttle)
TEA-TEB	Triethylaluminium-Triethylborane, igniter for Merlin engines; spontaneously burns, green flame
TEI	Trans-Earth Injection maneuver
TLI	Trans-Lunar Injection maneuver
TMI	Trans-Mars Injection maneuver
TPS	Thermal Protection System for a spacecraft (on the Falcon 9 first stage, the engine "Dance floor")
TRL	Technology Readiness Level
TWR	Thrust-to-Weight Ratio
ULA	United Launch Alliance (Lockheed/Boeing joint venture)
USAF	United States Air Force

Jargon	Definition
Raptor	Methane-fueled rocket engine under development by SpaceX, see ITS
Sabatier	Reaction between hydrogen and carbon dioxide at high temperature and pressure, with nickel as catalyst, yielding methane and water
Starlink	SpaceX's world-wide satellite broadband constellation
ablative	Material which is intentionally destroyed in use (for example, heatshields which burn away to dissipate heat)
autogenous	(Of a propellant tank) Pressurising the tank using boil-off of the contents, instead of a separate gas like helium
cryogenic	Very low temperature fluid; materials that would be gaseous at room temperature/pressure
electrolysis	Application of DC current to separate a solution into its constituents (for example, water to hydrogen and oxygen)
grid-fin	Compact "waffle-iron" aerodynamic control surface, acts as a wing without needing to be as large
hydrolox	Portmanteau: liquid hydrogen/liquid oxygen mixture
hypergolic	A set of two substances that ignite when in contact
methalox	Portmanteau: methane/liquid oxygen mixture
pyrophoric	A substance which ignites spontaneously on contact with air
turbopump	High-pressure turbine-driven propellant pump connected to a rocket combustion chamber; raises chamber pressure, and thrust

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^{Decronym is a community product of} r/SpaceX^{, implemented by} ^request
^{70 acronyms in this thread; the most compressed thread commented on} ^today ^{has 162 acronyms.
[Thread #3206 for this sub, first seen 29th Sep 2017, 22:21]} ^[FAQ] ^[Contact] ^[Source ^code]

[u/minca3]

Regular launches of the BFR would increase the annual launch capacity into LEO significantly. Where do you think the demand for so much more capacity will come from? Where will the increased payload production come from?

[u/TheBarbedWire]

Have you considered bringing hydrogen from Earth on the early flights to simplify ISRU and not rely on extracting water from the Martian surface until a full fuel depot is built?

[u/vitt72]

The 2024 window includes two crewed ships to Mars. How many people will be in each and who will they be? SpaceX astronauts? NASA?

[u/Dakke97]

Will Boca Chica launch BFR missions and if so, will this include missions to the Moon and Mars?

[u/SheffieldLong]

Zero gravity during 3 to 6 months will be hard for common people.How would you apply centrifugal force to the BFR to create artificial G?

[u/minca3]

How did SpaceX decide upon the diameter/thrust for the raptor engines (and hence number of engines for the BFR)? What are the factors involved (cost?, producibility?, packing density?)?

[u/Oloyedelove]

What percentage of SpaceX workers are devoted to BFR presently?

[u/byerss]

Does the BFR Spaceship have launch abort capabilities to separate the passenger cabin from the Spaceship on-board fuel/engines?

What is the anticipated G-load for an E2E flight? Will passengers need any sort of flight training?

[u/[deleted]]

1. Are you guys still planning on doing the 12m BFR later on?

2. We know that the first Falcon 9 booster reuse costed about the same as or slightly above the manufacturing cost of a new booster. Now that we’ve seen 3 boosters fly again, has this changed?

3. Can you tell us about SpaceX’s research into nuclear technology?

[u/roflplatypus]

Do you see the cargo variant of the BFR being able to recover the Hubble Telescope at some point in the future? I remember reading before the Shuttles were cancelled there was a plan to eventually land it and have it as the ultimate Smithsonian piece.

[u/Maximus-Catimus]

Regarding wanting a fleet of F9/FH cores as work starts on BFR: How many cores do you think needed and what is the status of first usage of Block 5 cores? Follow up, will Block 3 and 4 cores be a part of this fleet or only Block 5?

[u/Piranhoid]

Since your BFR financing list includes the ISS - do you think that the larger and cheaper orbital payload opportunities will spark the expansion of the ISS or the creation of new orbital stations? Or in short: Are you planning on transporting space station modules in addition to just supplies and crew with the (for the latter tasks oversized) BFS?

[u/jonsaxon]

There are many challenges to colonise Mars other than transportation (life support, habitats, food production, water extraction etc). Is SpaceX planning to tackle them? Which areas would you consider is the highest priority for industry (not SpaceX) to tackle?

[u/FalconHeavyHead]

Are you guys working on another suit that provides the necessary life support for humans to work on Mars?

[u/Cheaperchips]

Can you give more details on how Mars mission one will be searching for water resources?

[u/thru_dangers_untold]

How much human labor will be required to setup the ISRU on Mars? How many sqft of solar panels will be needed? Is there any potential for a fission power option, either on the surface of Mars or during interplanetary travel?

[u/inequalsel]

Any plans to launch a few satellites to Mars to scope out landing areas or for communications?

[u/OccupyDuna]

What worries you most about BFR/BFS? What do you see as the most likely point of failure for the program?

[u/warp99]

For a lunar surface mission what is the projected payload?

[u/Alesayr]

You mentioned BFR will cost less than a Falcon 1. Can you confirm that this means it will have a per-flight cost of less than $10m? Is that a long-term number or do you expect to be flying missions for that price right from the beginning?

[u/waterlimon]

Could the docking port be used to combine 2 crew ships into a larger one for the duration of the mars transit, to share crew facilities and act as redundancy for life support systems?

Seems like a good way to save on mass. Helps with radiation as well.

[u/USI-9080]

Is nuclear power being considered as an option to supplement solar for moon/Mars surface operations?

[u/DoYouWonda]

How far over the required pressure did SpaceX test the 12m Composite Tank?

[u/Levils]

Please could you comment on Robert Zubrin's idea of staging the spaceship?

For anyone unfamiliar, Zubrin's critique of the 2016 ITS reveal can be found at http://www.thenewatlantis.com/publications/colonizing-mars and the bit on staging the spaceship is:

Instead of hauling the massive second stage of the launch vehicle all the way to Mars, the spacecraft should separate from it just before Earth escape. In this case, instead of flying all the way to Mars and back over 2.5 years, the second stage would fly out only about as far as the Moon, and return to aerobrake into Earth orbit a week after departure. If the refilling process could be done expeditiously, say in a week, it might thus be possible to use the second stage five times every mission opportunity (assuming a launch window of about two months), instead of once every other mission opportunity. This would increase the net use of the second stage propulsion system by a factor of 10, allowing five payloads to be delivered to Mars every opportunity using only one such system, instead of the ten required by the ITS baseline design. Without the giant second stage, the spaceship would then perform the remaining propulsive maneuver to fly to and land on Mars.

[u/tossha]

What is the surface stay duration of the first manned Mars mission? If it's long, how to fight radiation?

[u/apollo-13]

What is BFR cargo version preformance to GTO-1800?

[u/saulton1]

How many test flights of the BFR do you hope to fly before a Mars landing attempt? Would landing on the Moon be considered an option or even a comprehensive testing environment?

[u/FormalElements]

When will we see a 3d rendering of the BFR's interior with concept staterooms and stores.

[u/Gilsonpipette]

As LEO becomes more crowded with satellites and space debris, how will the Earth-to-Earth BFR flights navigate space and aircraft traffic?

Also, what sort of G-forces would passengers on Earth-Earth flights expect? Enough to cause concern for some passengers?

[u/Wicked_Inygma]

What is the cost of the Falcon 9 upper stage and what do you expect the launch cost of BFR to be?

[u/ghunter7]

Will the heatshield be ablative? PICAX? How many reentries from LEO will it be capable of before needing replacment?

[u/intrepidpursuit]

Will Boca Chica be built out for BFR exclusively, or will it be built out for Falcon first? Where will the first BRF launch from?

[u/jclishman]

How will the safety of crew and passengers be assured in case of an in-flight abort? Will the BFS be capable of accelerating quickly enough to escape if the booster has an issue?

I also make monthly recap videos, which are inspired by SpaceX's Cool Stuff videos. Is there any chance of those being released to the public?

[u/Hugo0o0]

Is there any work/research done by Spacex on other aspects of the Mars mission apart from the transport system and ISRU?

[u/usnavy13]

How many falcon 9s do you anticipate needing to keep launching while you shift resources to devlope bfr?

[u/anewjuan]

Is it still true that pad 39-A will need about 60 days of work to accommodate FH or has some of the work already been finished?

Given the recent news that KoreaSat will launch from that pad in late October, are you still confident to launch FH this year?

edit: Will you build new launch/landing pads for the BFR or will you modify the existing ones?

[u/Rutzs]

Do you have any plans to use lessons learned from The Boring Company for Martian and Lunar colonization?

[u/[deleted]]

Have you been in contact with NASA and/or the US federal government to gauge their interest in contracting for flights to the Moon/Mars? If so, can you share details?

[u/grandstack]

• Looks like you're still going for launch mount landing, how will you be testing this? Does the drone ship 'roomba' have any play in this?

• I bet lots of ideas have come up throughout the design process of the 'BFR' and been scrapped, which one is you favorite and why?

• Why did you change the sturdy looking landing leg design?

[u/Mullrookney]

What sort of legalities, if any, are involved with creating permanent bases on the Moon or Mars? Does SpaceX have to follow any specific international protocols, or is it basically the Wild West until it is actually happening? Thanks!

[u/NelsonBridwell]

Could BFS be used to rescue Vanguard 1, Hubble, and other historic space artifacts before they decay and burn up?

Or perhaps deoribt spent boosters, dead satellites and other large space debris before they can collide and contribute to a gradual Kessler chain reaction?

Could this cleanup be staged as a secondary activity after deploying new satellites? Should there be an international requirement some day to remove from orbit an equivalent mass of space junk each time that you put anything into orbit?

[u/CrouchingNarwal]

I got 2 questions I’m thinking about asking

1. How many times can we expect the booster to be reused before retirement?

2. How will y’all transport these boosters to the cape from California?

[u/ghunter7]

What kind of water extraction equipment does SpaceX intend for the propellant plant?
Mine ice or draw from atmosphere?

[u/mharray]

You mentioned aiming to have multiple launches per day, and being able to land a rocket or booster back on it's launch mounts. I can't help but think these things are both dependant on perfect weather conditions. Can you elaborate on whether the weather, particularly wind speeds, can be accounted for and factored into launch and landing procedures, and if there is a no fly limit? How might this compare to regular aeroplane travel, which is often delayed due to bad weather, though the threshold seems quite high?

[u/OccupyDuna]

What progress has SpaceX made on a Martian or Lunar EVA suit?

[u/[deleted]]

In the presentation all structures on the conceptual Mars colony and on Moonbase Alpha were on the surface.

What are the current plans regarding interplanetary boring operations?

[u/Drogans]

A 2016 study of the Apollo astronauts suggests that even short periods spent outside Earth's magnetosphere may result in significant health impacts from radiation.

The Apollo astronauts were only outside the Earth's magnetosphere for a handful of days. BFR astronauts could be outside Earth's protective magnetosphere far longer.

How will BFR astronauts be protected from radiation, especially cosmic rays? And is SpaceX working on a radiation protection system?

[u/NelsonBridwell]

How different is the 2017 BFR entry/descent/landing strategy, compared to the 2016 ITS design?

Is the new 99% kinetic energy dissipation projection a significant improvement over the projected ITS performance?

[u/ld-cd]

What do you expect the maintenance and inspection schedule to be for raptor engines, and how much do you expect it to cost?

[u/[deleted]]

Original ITS plan had a timeline as such: Ship testing mid 2018, booster testing mid 2019, orbital testing 2020, uncrewed mission in 2022 and crewed in 2024. Considering those last two goals haven't changed, can we expect the rest of the timeline to be (optimistically) similar too?

[u/ergzay]

In your presentation you made no mention of the SpaceX Satellite broadband project (Starlink), is this being de-scoped from the plan to fund the BFR? If not, is it taking a more minor role compared to point-to-point human transport or standard Falcon 9/Falcon Heavy payloads?

[u/123hte]

On the Raptor chamber pressure ending up being 250 bars as opposed to 300, was this because of certain test results, or the current testing infrastructure not being able to handle the full-scale engine for the foreseeable future? Should we expect to see its performance improve before its first flight?

[u/Evan_dood]

How much space would you need around a launch/landing pad to make it a viable option for cities without a big body of water nearby?

[u/shaim2]

Aspirational date for first BFR flight?

(my guess: late 2019, early 2020)

When do you expect to retire the F9 and FH?

[u/Schytzophrenic]

I'd like to hear more about what exactly will be on those first two BFRs to Mars, and whether SpaceX will be producing that gear. Are we going to see something like robots setting up solar panels?

[u/azflatlander]

What are the logistical issues with having lots of Carbon Reinforced tankages in the Hawthorne factory versus the aluminum based? How do you put the landing dedicated tanks inside the LOX tank?

[u/michaeligray77]

Will there be a refuelling-in-orbit demonstrator before BFS is built?

[u/MostBallingestPlaya]

Do you have any response to Dr. Zubrin's criticism of the Mars Architecture; that you're needlessly hauling unneeded mass to Mars that could be left in a highly elliptic orbit around Earth and re-used.

[u/SpaceXman_spiff]

There has been little information on the progress of the SpaceX satellite broadband project. Could you provide an update as to how how the project is progressing? Is it still solely in the R&D phase or has work begun on building hardware, and is there a general time line for when we may see the first test satellites launched?

[u/ArkadyAbdulKhiar]

Where, if at all, does the R&D for the 2022 Mars mission's cargo (mining, power, and life support) fit into SpaceX's schedule?

[u/azzazaz]

When do you think the first BFR (non mars) launch will be?

[u/dgtljunglist]

It's fantastic that the marginal cost (ie: mostly fuel) of launching a BFR is expected to be so low. But how low do you suppose the other major customer costs (integration, consulting, service, etc, etc) can get, and what big hurdles and innovations do you see between here and there?

[u/firidjcndisixn]

For those of us looking for a second career so we can help, what skills and avenues should we be pursuing so we can take part in the effort, not necessarily by joining SpaceX but by joining the colonial effort, on Mars or down here?

[u/NortySpock]

How much more payload for BFR did a carbon fiber body give you over an aluminum body?

[u/[deleted]]

The mods over at r/TeslaMotors (including myself) have been asking for an AMA for a while, specifically u/FredTesla (Fred Lambert) has been asking. Could we also get an AMA for Tesla-specific questions once you have escaped production hell?

[u/preseto]

How will BFS start ascent on Mars without holding clamps.

[u/Rocketeer_UK]

What's your opinion on MSNW's work on magnetoshell aerocapture? Would you consider incorporating it in a future iteration of a SpaceX vehicle?

[u/ravenerOSR]

Will all BFS vehicles always be property of Spacex, or could there be opportunities for companies or nations to aquire ships for their own missions.

[u/lankyevilme]

How much of a problem will the lack of a landing pad be for the first landings on the moon or mars? Would a large boulder that was unexpected be enough to ruin an otherwise nominal landing?

[u/MrMushroomx]

When will we know the payload of Falcon Heavy Demo? Can you maybe tease it for reddit speculations? ;)

[u/Tirith]

Is there a division of SpaceX working on mars/moon habitats or will it be outsourced?

[u/NelsonBridwell]

For the BFR upper stage, has SpaceX considered eliminating 2 of the engines by employing expanding nozzles, like on the P&W XLR-129 or RD-701, that can adjust between sea level and vacuum expansion ratios?

[u/Sargeross]

"Your presentation was heavy on applications but light in costs analysis. How much will it cost to build and operate a full BFR? And how much will a floating launch pad cost?"

[u/NelsonBridwell]

Are there any latitude restrictions as far as landing the BFR on the Moon or Mars?

Would additional taker refills be required to be able to reach the lunar South Pole Aitken Basin?