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Musk IAC Press Q&A Transcript
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2016-10-04-iac-hero.jpg
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Image credit: SpaceX {:.muted.halfx.small-font}

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Hesitations have been edited out for readability's sake, unless they are contextually useful. Words that I was unable to hear are marked within square brackets: [...]. Any words I'm unsure about are also in [square brackets]. My comments are in {Curly braces}. Emphasis is mine.

This is the transcript taken from the below recording, with times added above each speaker.

<iframe src="https://www.youtube.com/embed/hNlGkqTYsI4?rel=0&controls=1&showinfo=1" frameborder="0" allowfullscreen></iframe>

{The first question Musk answers is not included in the recording.} {:.muted}

00:00 {:.muted.smaller} Musk: {:.small-caps.strong}

Any [enterprise you can imagine] on Mars, things that are, we [take for granted] on Earth as well as things that [won't exist anywhere] but Mars, so we're [like the Union Pacific^unionpacific] so, our goal is to get people there, we'll need to construct the initial propellant plant to produce [much] propellant on Mars, and so the initial, [obviously] the Mars spaceport and the sort of the beginnings of [a key] central element [of] a Mars base and then thereafter, um, and we definitely wanna make sure we [don't infringe] upon the opportunities that people may have to create things on Mars, and if [people thought that] SpaceX is just gonna do that then they [they’ll] be less willing to do it so [we're really] trying to create a conduit to Mars to enable people to do an incredible [number of] things there.. [And just like how the Union Pacific, sort of, made California really,] um, we'd like to have it be that way for Mars. I think there is, um, like I say I'm not too worried about safety on the way there from radiation, I think that's basically is {Gets cut off by question}

01:26 {:.muted.smaller.right} Question Asker 1: {:.small-caps.strong.right}

[Well not just] radiation but also micro-gravity, and the life support systems. Is that also [included] in the Architecture [...]? {:.right}

01:34 {:.muted.smaller} Musk: {:.small-caps.strong}

Yeah yeah, I think those are essentially solved problems, we've been able to have astronauts on orbit for well over a year and this is a three month [journey, so] really I think that's more or less a solved problem, you could do it in a more [mass efficient ways], it's not a [fundamentally] new technology [keeping people alive] in space. I would say that's fairly straightforward. I'd say the challenge really is getting there, and the huge challenge is making it something - [making the cost such that] enough people [can afford to go] to make it a self sustaining civilisation, that's the [monumental] challenge.

02:26 {:.muted.smaller.right} Question Asker 2 (Reuters): {:.small-caps.strong.right}

Thanks for coming over here, I wanted to ask you first about if funding this mission would affect any of [your holdings ... and in other words as you tap out other assets to fund this] and if you could clarify a little bit about [the] time to get to Mars, I think I heard you say 90 days but [for this flight]? Thanks. {:.right}

02:50 {:.muted.smaller} Musk: {:.small-caps.strong}

Well I mean the [interplanetary transit] time is pretty straightforward, it just depends on your departure velocity [from Earth], the synchronisation event only occurs [every] [26] months, [so] every 26 months there's approximately a 6 month window [where] you can do a Mars transit, which kinda makes sense because Mars has, takes [... {22.5}] months to go around the Sun, and you can basically transit to Mars when you're in the right quadrant, you can't go [when] it's on the other side of the Sun, and the faster you exit Earth the quicker you can got to Mars so the low energy transition to Mars, or transit to Mars would be [6 to 7] months, that would be [dV[^dv]/maybe] 4.5km/s departure velocity, at 6km/s you can drop that down to, so roughly 3 months, and over time I expect that number will come down to [perhaps] under a month, although the amount of [kinetic] energy you need to do that, and to then [obviously] high energy [aero]breaking is substantial so I [...] [any service to Mars] [...] quite energy expensive.

[^dv]: Delta-V (velocity) https://en.wikipedia.org/wiki/Delta-v

04:12 {:.muted.smaller.right} Question Asker 2 (Reuters): {:.small-caps.strong.right}

Thanks, and then [finally] your personal investment in this, and you're chairman Tesla, SolarCity what do you [tap out] if anything [to fund it]? {:.right}

04:22 {:.muted.smaller} Musk: {:.small-caps.strong}

I can't comment on public company [...] because you know the [consequences] of that would be quite severe, [...] at some point in the future, not immediately, the reason that I'm accumulating personal assets in order to fund [humanity] becoming a multiplanetary species. [There's some other] things I'm funding as well, [...] healthcare, environmental issues, and education but, um, I mean AI [safety], but really the primary [thing], the thing that will [absorb almost all our] resources is the [establishment] of a [self-sustaining civilisation] on Mars. I have no reason to [accumulate] resources beyond that, [in fact].

05:12 {:.muted.smaller} Musk (or Moderator): {:.small-caps.strong}

Can I ask everyone to [limit it] to one question, Than you.

05:15 {:.muted.smaller.right} Question Asker 3 (BBC): {:.small-caps.strong.right} {Even as a Brit this question was really confusing} {:.muted.right}

One question, [...] of the BBC, see [you are plotting] to go, you talk about your timeline [launching] to Mars into early 2020, are you going to launch any sort of website where [each can] come and register, maybe like one of Mars[One] you know [it's really interest] so [if it then doesn't happen] so [people think "Oh I can't do anything" they can get really] engaged? {:.right}

05:44 {:.muted.smaller} Musk: {:.small-caps.strong}

I think when we get closer to actually sending people to Mars, [we're gonna wanna, we'll try to get] some sense of what the demand level is, and you know people could [perhaps] put down a small down-payment on a trip to Mars, but we want to get pretty close to the actual trips and be highly confident that we [can meet cost targets] within [a reasonable] the time-frame before we would do that, certainly [maybe] two or three years before an expected launch [date].

06:21 {:.muted.smaller.right} Question Asker 3 (BBC): {:.small-caps.strong.right}

{Asks to clarify the last sentence of Musk's response} {:.muted.right}

06:31 {:.muted.smaller} Musk: {:.small-caps.strong}

Basically two or three years before an expected launch. We wanna make sure we know what it actually is going to cost and the time [certainly] a year or two [before] taking, accepting advance orders.

06:48 {:.muted.smaller.right} Question Asker 4: {:.small-caps.strong.right}

Can you talk a little bit more about the cryogenic on-orbit refuelling, [what're] the technical challenges with that and do you have plans to [fly with] that in the future? {:.right}

07:13 {:.muted.smaller} Musk: {:.small-caps.strong}

On-orbit refuelling essentially it's about having two spacecraft, yeah, ahem, dock, mate and exchange fluids (there's certainly a joke in there somewhere). [But we've] already docked with the space station, and [well technically it's called berthing,] but it'll be an autonomous docking, probably an autonomous docking capability around the end of next year, and so having fully autonomous docking capability basically gives you on-orbit [refilling]. [When I say ] refuelling... I use the word refilling because there's 3 and a half times as much oxygen as there is fuel and the [oxygen fuel ratio is 3.5 to 1 so really it's] reoxing {sic} [rather than] refuelling, that's actually what it amounts to. Actually I think that's going to be a relatively straightforward element, if we can dock with the space station which is a very complex docking manoeuvre, the [NASA requirements] are quite severe for space docking, then having two spacecraft dock in orbit is not too much of a problem.

08:30 {:.muted.smaller.right} Question Asker 5 (PBS): {:.small-caps.strong.right}

What're the obstacles you can't control that you need to be able to overcome to accomplish this goal? {:.right}

08:38 {:.muted.smaller} Musk: {:.small-caps.strong}

[Stuff] that I can't control? Well I guess there's always space [and fortune]. Really the pace of progress on Mars depends on the pace of progress of SpaceX to [what degree do we] achieve a good launch [rate], our success rate with Falcon 9 is roughly 93%, it's not out of [family] with some other launch vehicles, but it needs to be a lot better, and we, the Falcon Heavy the launch timeline, [Dragon 2], and make sure that we [manage the company such that we've got sufficient cashflow to] fund [Mars properly], and of course I will [supplement that] personally. [And I think there may be other] individuals who are willing to do that, and [conceivably at] some point in there future there may be a -- well I have no idea if there will be but there might be a NASA [COTS] programme, or something like that. [...]necessary really, this is ultimately about maximising probability that the future is good and minimising existential risk, so I think [whatever means] increases that probability is good. So I [don't see any] fundamental [technical] obstacles to what we've proposed [...] [a lot of hard engineering though]

10:30 {:.muted.smaller.right} Question Asker 6: {:.small-caps.strong.right}

[....] You propose a manned mission to Mars could arrive in 2025, is that still [your plan] and would it be on the Falcon Heavy rocket or on the New Rocket that you've presented today and then how [fast will you build up to that vision] of having 100 people [fly] to Mars? {:.right}

10:58 {:.muted.smaller} Musk: {:.small-caps.strong}

For sending people to Mars [it] definitely would be Interplanetary Transport System would be what we'd send people with, it could technically be done with a bunch of Falcon Heavy launches but you really wouldn't want to travel to Mars in a Dragon, the interior volume is roughly equivalent to that of a large car, so 3 months is a long time to spend on a car, and we [really] need to transport a lot of equipment there. So the first mission with people on it would [be with sort of] the Heart of Gold Spaceship[^heartofgold], so from a [time-based] standpoint we aspire to launch in late 2024 with an arrival in 2025, but that's optimistic [so I would stress] that that's aspiration and within the realm of possibility, but a lot of things need to go right. That said I don't think [we'll be significantly] beyond that [if it should go later].

[^heartofgold]: Elon indicated that he would like to name the first ITS Spaceship the Heart of Gold in the main keynote, after one of the spaceships in Douglas Adams' Hitchhiker's Guide to the Galaxy https://en.wikipedia.org/wiki/Technology_in_The_Hitchhiker%27s_Guide_to_the_Galaxy#Heart_of_Gold

12:22 {:.muted.smaller.right} Question Asker 7 (Washington Post): {:.small-caps.strong.right}

Leading up to today there was a lot of anticipation and then after the September 1st failure[^amso6failure] you started hearing concerns about saying you should be focused on Falcon 9 and commercial crew and getting astronauts to LEO and the station {ISS} [...] coming up. I wonder if you could address those and what your response is to all that? {:.right}

[^amso6failure]: Launch Vehicle failure of the Falcon 9 during a static fire prep http://www.spacex.com/news/2016/09/01/anomaly-updates

12:48 {:.muted.smaller} Musk: {:.small-caps.strong}

I haven't actually [...]... I mean, less that 5% of SpaceX's resources are working on the Interplanetary Transport System, so it is very much a secondary or tertiary priority to [ascertaining] exactly what happened on the last mission {AMOS6}[^amso6failure], last [...] flight, or almost flight, the most taxing and difficult thing, um yeah. It would be incorrect to say it's anything other than our absolute top priority to understand exactly what went wrong there and what we can do to prevent anything like that in the future. [We've] eliminated all the obvious possibilities for what occurred there so what remains are the less probable answers. But anyway this is the [small things] on a long road. There will probably be other failures in the future, and we've not lost a single contract as a result of the it, people in the launch business understand that is something happens. With SpaceX it gets, I dunno, 100 times more press than if another rocket fails. Maybe 1000. And so the public tends to think only our rocket fails but actually lots of rockets fail.

14:27 {:.muted.smaller.right} Question Asker 8 (New York Times): {:.small-caps.strong.right}

[I believe you gave that you have to have] $10Billion [and I was wondering what] that includes [, does it include a Mars port?] And could you describe what sort of public private [partnerships] you're envisioning to help pay for it, or are you hoping for a NASA contract? {:.right}

14:44 {:.muted.smaller} Musk: {:.small-caps.strong}

Um yeah, when I founded SpaceX I had no expectation of any government contracts, I [founded] SpaceX with entirely my own money, [out of] $180 Million from the sale of PayPal to Ebay, [of which] $100 Million went into SpaceX, $70 Million to Tesla, $10 Million to SolarCity, [so] everything actually but uh; I expected the most likely outcome was failure, although I should say originally I thought I would only spend [$50Million] on SpaceX and have $20 Million left over but then [I couldn't let my baby die] so I put all in. The I... [A common criticism is that somehow I'm after the government's money] by various arseholes out there, really, so... NASA is our most significant customer, we do about [20 of our launches] but 3/4 of our launches are commercial. In the future, there may be a NASA contract, there may not be, I don't know. If there is that's a good thing, if there's not probably not a good thing, because there's larger issues than space here, are we humans gonna become a multiplanetary species or not? Not [pedestrian] questions of is it public or private or what the percentage [is. These are] small and [tawdry] questions.

16:37 {:.muted.smaller.right} Question Asker 9 (Aviation Week): {:.small-caps.strong.right}

We haven't heard much from [your side] about the near-term missions to Mars you're working on, using the Dragon 2 or Red Dragon [...] I wonder if you could walk us through what you hope to accomplish with these missions? How in [the ...] you expect I guess one per planetary opportunity and wether, um, you know if you'll make payload space available to NASA or other [companies/countries]? {:.right}

17:09 {:.muted.smaller} Musk: {:.small-caps.strong}

Really we wanna use Dragon, Dragon 2 to be a pathfinder, if it's anything to go by. We need to sort out interplanetary navigation, [deep space] communication [at] high bandwidth, uh, there's currently no high-bandwidth deep-space communication system, and then entering the Mars atmosphere, and landing. What's landing like if you're heavy - I mean, Dragon will be about 10 times heavier than anything that's landed on Mars before, and it will land with thrusters close to the surface. So with Curiosity they [really were concerned about having thrusters close to the surface, which is why they used] this sort of hovering thing, there's no way to do that with a giant Spaceship. [There's key questions like] if you're coming in hot and fast, then you ou dig a big hole in the ground. What kind of dust and rocks do you throw up? The Mars [surface is actually] pretty hard, how well does it hold up to rocket blasts? [They're all tough] questions. I wouldn't give the first Dragon landing high odds, maybe [50%], maybe 50%. The history of landing on Mars is not a good one, [actually for] those familiar with Mars. So for a first timer I'd say pretty good - [if we have] a 50% likelihood I'd say that's pretty good. We're just [gotta think about] all the issues, sending them on every opportunity, maybe sending 2 in 2020 and then also we wanna find out what's the easiest way to get water - because water's [useful] for doing the [local] propellant production. Carbon Dioxide is easy, it's in the atmosphere. So we're looking to make sure the dust filters, you can clean the dust filters [but getting the CO2 should be easy]. Getting the water, much harder. There's ice all over Mars, but in what form, how dirty is the ice, how much energy do you need to use to extract the water, because there's only a small water percentage per unit mass of the regolith, you're [gonna use] more energy to heat it, to purify it so how to [deal with ... is one of the biggest issues.]

20:00 {:.muted.smaller.right} Question Asker 10: {:.small-caps.strong.right}

I noticed on [...] options list there there was no mention of Satellites, you've spoken before about a SpaceX satellite constellation that might provide revenue, a cash flow for this or other missions. Is that still part of the SpaceX plan? {:.right}

20:17 {:.muted.smaller} Musk: {:.small-caps.strong}

[We] have some ideas about a satellite constellation but now's not the time to talk about them I think [we'll reserve that] for a future event. There's certainly a lot of opportunity there, [they'll certainly] be very helpful in funding a Mars [city].

20:40 {:.muted.smaller.right} Question Asker 11 (National Geographic): {:.small-caps.strong.right}

I was wondering about the Planetary Protection aspect of sending spacecraft to Mars and putting Humans on Mars and if this is something you've though about; if so, what issues do you consider [...] question [and] do you have any potential solutions? {:.right}

21:00 {:.muted.smaller} Musk: {:.small-caps.strong}

We've really not seen any sign of surface life on Mars, there's clearly nothing on the surface of Mars. There may be subterranean [chemotrophic] bacteria, I suspect they're pretty hardy and there's not much we could do to take them out even if we wanted to. So that's what we're really talking about in terms of planetary protection. The planet we should be concerned protecting is Earth - that's where life exists as we know it, in abundance. [To a certain extent] we are life's [agents], we can bring life as we know it and breathe life into Mars where it [doesn't exist] today, and ensure that if there is some kind of cataclysmic event on Earth that life as we know it continues to exist.

22:03 {:.muted.smaller.right} Question Asker 12: {:.small-caps.strong.right}

{Start of question is hard to get} [...] Why focus on developing new technologies to make us multiplanetary rather than developing technologies that can help us save the Earth? {:.right}

22:20 {:.muted.smaller} Musk: {:.small-caps.strong}

Well you know I do have another day job... Tesla is doing electric [cars and] solar power, [I think] important part of making Earth's future good, we have to have sustainable energy generation, energy consumption, and the one thing I forgot to mention actually [is the fact] that we're going to use solar power on Mars to create fuel and oxygen, that same [thing] in the long [term] could be extended to Earth, where we can actually extract CO2 from the atmosphere, combine it with water and [bind] it to form CH4O2, so in the long term it could be equally sustainable fuel source on Earth as well.

23:12 {:.muted.smaller.right} Question Asker 13: {:.small-caps.strong.right}

We're [just] beginning to talk [to] possibly growing plants on Mars if you were to change the atmosphere, you didn't get into that any further, is that a separate track of research you're working on, [could you] take that a little bit further? {:.right}

23:23 {:.muted.smaller} Musk: {:.small-caps.strong}

You mean the Mars Oasis thing or... Sorry [what's your question?]

23:28 {:.muted.smaller.right} Question Asker 13: {:.small-caps.strong.right}

You think you could [raise the pressure] on Mars or? {:.right}

23:31 {:.muted.smaller} Musk: {:.small-caps.strong}

Yeah yes, absolutely. In the long term if you warm the planet up there's a lot of carbon dioxide and ice on Mars, so um if you warm the planet up you actually create oceans, there [used to be] oceans on Mars, [but] it got too cold, and then over a [billion] years a large part of the atmosphere kind of was blown away by the solar wind, but that happens over timescales of hundreds of millions [or] billions of years, so if you warm the planet up you will densify the atmosphere, and just with atmosphere [densification] and um, there may need to be protection, there may not need to be protection, you could grow plants on the surface of Mars. You can basically terraform Mars to make it an Earthlike planet.

24:23 {:.muted.smaller.right} Question Asker 13: {:.small-caps.strong.right}

[So do yo have] the intention to terraform Mars and what the method is for that? {:.right}

24:29 {:.muted.smaller} Musk: {:.small-caps.strong}

Terraforming [...] will take place over a long period of time, and I think ultimately would be the decision of the people of Mars. We need to get there in the first place, [worry about] getting there in the first place. [Otherwise it's a little academic]

24:47 {:.muted.smaller.right} Question Asker 14 (Netflix Originals){Sic} {:.small-caps.strong.right}

Talk to me about getting there in the first place. Can you talk about some of the short-term concrete benefits of sending people to Mars in the near future? {:.right}

25:03 {:.muted.smaller} Musk: {:.small-caps.strong}

Well the larger point is creating a self-sustaining civilisation on Mars to provide insurance for life as a whole, life as we know it, [we're] backing up the biosphere, it really is the decision as to whether or not we want to become a multi-planet species, a spacefaring civilisation or not, some people think [it's fine] to stay on Earth forever [...] but I think the future where we are a spacefaring civilisation and out there amongst the stars is infinitely more exciting and inspiring than one where we are not. Basically I think you have to [hate] humanity if you don't like that future.

25:48 {:.muted.smaller.right} Question Asker 14: {:.small-caps.strong.right}

What're the implications of not going? {:.right}

25:50 {:.muted.smaller} Musk: {:.small-caps.strong}

Well, being confined to one planet until [an] eventual extinction event.

29:08 {:.muted.smaller.right} Question Asker 15 (Thomas Schumann, Scienceblog.dk): {:.small-caps.strong.right}

I just came here now [...] launch capability on the booster {:.right}

26:24 {:.muted.smaller} Musk: {:.small-caps.strong}

I did not understand your question

26:26 {:.muted.smaller.right} Question Asker 15 (Thomas Schumann, Scienceblog.dk): {:.small-caps.strong.right}

Launch Abort {capability on the booster} {:.right}

26:29 {:.muted.smaller} Musk: {:.small-caps.strong}

{Note, this answer is clearer because of an altenate recording} {:.muted}

Oh launch abort, the spacecraft itself is capable of aborting from the booster, the erm... Launch abort on the spaceship itself is kinda pointless, if you're on Mars you're taking off or you're not taking off. You know, parachutes don't work too well and [you can't have] some standard abort system, and just how do you abort 100 people it's just not feasible, the key is to make the spaceship itself extremely safe and reliable, and have redundancy in the engines, high safety margins and have [it be] well tested. Much like a commercial airliner. Like they don't give you parachutes.

27:22 {:.muted.smaller.right} Question Asker 15 (Thomas Schumann, Scienceblog.dk): {:.small-caps.strong.right}

But you're saying the vehicle itself would be able to separate from the booster? {:.right}

27:24 {:.muted.smaller} Musk: {:.small-caps.strong}

Yeah, the spaceship could separate from the booster and fly away from the booster if there's a problem at the booster level.

27:32 {:.muted.smaller.right} Question Asker 16: {:.small-caps.strong.right}

I dunno if anyone's asked you this question before but what kind of data are you getting from and sending to NASA and the other space agencies, in regards to this new, bold plan to colonise Mars? {:.right}

27:54 {:.muted.smaller} Musk: {:.small-caps.strong}

Well we're in constant communication with NASA particularly since we work with them on many levels, [I] provided part of the presentation today to some of the NASA senior management ahead of time, [we] only really finished the presentation early this morning so you're seeing it fresh.

28:17 {:.muted.smaller.right} Question Asker 17: {:.small-caps.strong.right}

{Very clipped audio, not much of this was understandable} {:.muted.right}

I SpaceX trying to [...] Mexico? Mexico [...] Is Mexico part for this great plan to go to Mars? {:.right}

28:48 {:.muted.smaller} Musk: {:.small-caps.strong}

Because of ITAR constraints it's quite hard for us to do manufacturing or source components from outside the US, whereas this is different for Tesla. [It has nothing to do with] some sort of desire to only source things from the US on the part of SpaceX, because rockets are considered advanced weapons technology it's very difficult for us to make it more international. We'd like to but we can't, that's against the law. Tesla is much more international because it is not against the law.

29:26 {:.muted.smaller.right} Question Asker 18: {:.small-caps.strong.right}

I have a question about shielding technology, as you know in space [there are a lot of micro-dust], fragments of meteorites and stones and a large piece could damage the ship so I want to ask you about the [status] of shielding technology and how you plan to [apply] it to the ship {:.right}

29:54 {:.muted.smaller} Musk: {:.small-caps.strong}

Yeah I [...] shield, so a Dragon has impact shielding as well as thermal shielding and we'd have shielding as well on the spaceship. The other value is scale of the spaceship that the walls will be so strong that actually they could resist a lot of micrometeorite impact by themselves, but [it's] something that we understand quite well and something that we have on our Dragon spacecraft. It's not [something] that's a problem in deep space or on Mars, it's just something that tends to be a problem [at] certain altitudes on Earth orbit.

30:37 {:.muted.smaller.right} Question Asker 18: {:.small-caps.strong.right}

So are there plans to create any [energy] shields [...] {:.right}

30:39 {:.muted.smaller.right} Random Audience Member {:.small-caps.strong.right}

Noooooo {:.right}

30:42 {:.muted.smaller} Musk: {:.small-caps.strong}

Energy shields?! Uh

30:44 {:.muted.smaller.right} Question Asker 18: {:.small-caps.strong.right}

Like the ship is protected by a [thick] wall, you put material in the ship that are strong enough to contain any damage from the microfragments {:.right}

30:51 {:.muted.smaller} Musk: {:.small-caps.strong}

Yeah yeah

30:54 {:.muted.smaller.right} Question Asker 18: {:.small-caps.strong.right}

So what about energy shields, are you planning to... {:.right}

30:56 {:.muted.smaller} Musk: {:.small-caps.strong}

Well maybe you're referring to having a big sort-of electromagnetic [field] around the ship, that's not going to be very helpful against micrometeorites but it could be helpful [if you have a big enough field] for alpha particles from the sun or any kind of high energy charged particle, if you have a big enough field [should deflect that]. [So that could be] useful in the future.

31:25 {:.muted.smaller.right} Question Asker 19 (SpaceFlight Now): {:.small-caps.strong.right}

So we noticed that [now you have it looks like] you have like three grid-fins, three landing legs, can you talk a little bit about that design change, why you went from four down to three? {:.right}

31:36 {:.muted.smaller} Musk: {:.small-caps.strong}

Well you only really need three. Well so for control, technically you can get away with two grid-fins in a V configuration, with three you're really doing fine, you essentially want to control pitch, yaw, and roll and [just like] an aircraft [with an empennage, where you've got] a rudder and an elevator, and ailerons -- three gives really good control on [three] axis but four is kinda redundant - I guess there's some value to having redundancy but you really only really need three.

32:20 {:.muted.smaller.right} Question Asker 19 (SpaceFlight Now): {:.small-caps.strong.right}

In that case do you still have control ability with 3 going down to 2 if something happens to 1? {:.right}

32:25 {:.muted.smaller} Musk: {:.small-caps.strong}

Umm, you could probably [correct] with attitude control thrusters [at the expense] of additional propellant. The really hard one is pitch. Pitch requires, you need a really powerful thruster to control pitch, to that's really the control dimension that's the hardest which you can do with just two fins.

32:45 {:.muted.smaller.right} Question Asker 19 (SpaceFlight Now): {:.small-caps.strong.right}

Well I mean, in the Mars entry it shows the craft coming in on the long side of it, [how] does it have that enough control authority to get pitched up and actually put the tail down? Heavy thrusters that can... {:.right}

33:00 {:.muted.smaller} Musk: {:.small-caps.strong}

Yeah, yeah there'll be heavy duty control thrusters on the spacecraft, and they won't be cold gas they'll be gaseous Methane-Oxygen and [they'll certainly be] pretty powerful for attitude control thruster [terms]. I mean you're talking 10 ton {Assuming metric} thrust-pack thrusters, or if not more. The thing to remember with Mars is once you've slowed down, once you're subsonic the atmospheric effects are very weak because the atmospheric density is so low so you really - it's a lot easier to control with thrusters than on Earth because [those aero] forces are massively diminished.

33:49 {:.muted.smaller} Musk or Moderator: {:.small-caps.strong}

Thank you, that's all the time we have for questions, if you have any follow-up please send to media@spacex.com. Thank you.


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