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Elon Musk’s SpaceX AMA: Living on Mars, Spaceship Info, Timeline
SpaceX CEO Elon Musk hosted a Reddit AMA (Ask Me Anything) earlier this afternoon and spent several hours drinking whiskey, trolling the audience, answering some great questions, and generally having a blast. He revealed a vast array of fascinating new details about SpaceX’s giant new rocket (BFR), its upper stage spaceship (BFS), and much more.
All of Musk’s answers from the AMA have been collated and organized by category below. You’ll want to shy away from the AMA page itself, currently clocking in at more 10,000 comments.
When useful, particularly dense and technical responses have been summarized in italics for a broader audience.
Living on Mars
Q: Obviously there will be an extreme amount of care put into what is sent on the first missions, and the obvious answer of “Solar Panels” and “Fuel Production Equipment” is included, but what else?
A (Elon): Our goal is get you there and ensure the basic infrastructure for propellant production and survival is in place. A rough analogy is that we are trying to build the equivalent of the transcontinental railway. A vast amount of industry will need to be built on Mars by many other companies and millions of people.
Q: Does your Mars city feature permanently anchored BFS spaceships?
A (Elon): Wouldn’t read too much into that illustration
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The aforementioned Martian city. Spaceships can be seen near the center. (SpaceX)
Q: Have any candidate landing sites for the Mars base been identified?
A (Elon): Landing site needs to be low altitude to maximize aero braking, be close to ice for propellant production and not have giant boulders. Closer to the equator is better too for solar power production and not freezing your ass off.
Q: Who will design and build the ISRU system for the propellant depot, and how far along is it?
A (Elon): SpaceX. Design is pretty far along. It’s a key part of the whole system.
Without ISRU (In-Situ Resource Utilization), BFS is unlikely to ever be able to take humans to Mars affordably enough to enable large colonies. This news is thus of huge importance, and suggests that SpaceX will be able to focus on developing BFR and BFS near-term.
Another hypothetical SpaceX city on Mars. Bases will need to be located near water resources. (SpaceX)
SpaceX Big F** Spaceship (BFS)
Q: Will the BFS landing propellants have to be actively cooled on the long trip to Mars?
A (Elon): The main tanks will be vented to vacuum, the outside of the ship is well insulated (primarily for reentry heating) and the nose of the ship will be pointed mostly towards the sun, so very little heat is expected to reach the header tanks. That said, the propellant can be cooled either with a small amount of evaporation. Down the road, we might add a cryocooler.
A (Elon): exactly (while methane could be kept in its liquid form solely through high pressure storage, the pressures required are immense and would require tanks that would be far too heavy for a rocket’s second stage.
Cold liquid oxygen and methane will unavoidably warm up over time, eventually returning to their gaseous forms if allowed. SpaceX’s solution for BFS, which will spend several months between Earth and Mars, is to rely on the Ship’s already great insulation, as well as minimal evaporative cooling (similar to how swamp coolers work).
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Q: Will the BFS heat shield be mounted on the skin, or embedded?
A (Elon): The heat shield plates will be mounted directly to the primary tank wall. That’s the most mass efficient way to go. Don’t want to build a box in box.
Dragon 2’s PICA-X heat shield can be seen on the right. BFS’s heat shield will be made of the same material, albeit on a much larger scale. (SpaceX)
Q: Can the BFS delta wings and heat shield be removed for deep space missions?
A (Elon): Wouldn’t call what BFS has a delta wing. It is quite small (and light) relative to the rest of the vehicle and is never actually used to generate lift in the way that an aircraft wing is used.
Its true purpose is to “balance out” the ship, ensuring that it doesn’t enter engines first from orbit (that would be really bad), and provide pitch and yaw control during reentry.
Q: Why is the 2017 BFS spaceship largely cylindrical?
A (Elon): Best mass ratio is achieved by not building a box in a box. The propellant tanks need to be cylindrical to be remotely mass efficient and they have to carry ascent load, so lowest mass solution is just to mount the heat shield plates directly to the tank wall.
For a rocket, mass ratio refers to its weight with a full load of propellant divided by its weight while completely empty. The lighter a rocket’s structure, the more mass it can lift into a given orbit.
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- SpaceX’s conceptual Interplanetary Transport System from 2016 was considerably larger and more structurally complex than 2017’s BFR. (SpaceX)
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- The relatively cylindrical BFS reduces complexity and lowers weight. (SpaceX)
Q: How does the BFS achieve vertical stabilization, without a tail?
A (Elon): Tails are lame
A (Elon): +1 (The space shuttle’s vertical stabilizer was completely useless for most of the reentry profile, as it was in complete aerodynamic shadow. I think it’s clear a craft doesn’t need one for reentry, only for subsonic gliding, which BFS doesn’t really do.)
BFS doesn’t need a tail because tails add weight, are of little use during orbital reentry, and BFS is not intended to glide.
Q: Why was the number of BFS landing legs increased from 3 to 4?
A (Elon): Because 4
A (Elon): Improves stability in rough terrain
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Q: How is the radiation shielding in the ITS?
A (Elon): Ambient radiation damage is not significant for our transit times. Just need a solar storm shelter, which is a small part of the ship. Buzz Aldrin is 87.
While radiation fearmongers may balk at this statement, it is to some extent true. The risks from radiation (PDF) for a six month journey in deep space are approximately similar to several dozen CT scans, while two years spent on the surface of Mars with little to no shielding would result in about the same amount of exposure. Underground habitats could alleviate a considerable amount of the risk from living on Mars’ surface.
The issues and dangers posed by radiation ought not be trivialized but they can be dealt with, particularly if BFR can deliver massive payloads to the planet.
Q: Why was the location and shape of the BFS header/landing tanks changed?
A (Elon): The aspiration by the change was to avoid/minimize plumbing hell, but we don’t super love the current header tank/plumbing design. Further refinement is likely.
Header tanks refer to smaller tanks contained within the main propellant tanks that are used to ignite engines in microgravity. It’s easier to pressurize or simply fill the smaller tanks than it is to do so with the massive main tanks.
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BFS’ header tanks circled in red. (SpaceX)
BFS Tanker
Q: Will the BFS tanker’s payload section be empty, or include extra propellant tanks?
A (Elon): At first, the tanker will just be a ship with no payload. Down the road, we will build a dedicated tanker that will have an extremely high full to empty mass ratio (warning: it will look kinda weird).
Using one version of the BFS as both a tanker and ship will streamline the initial development process for the rocket.
Two Spaceships docked for refuelling. (SpaceX)
Q: Will the BFS tanker ships (have to) do a hoverslam landing?
A (Elon): Landing will not be a hoverslam, depending on what you mean by the “slam” part. Thrust to weight of 1.3 will feel quite gentle. The tanker will only feel the 0.3 part, as gravity cancels out the 1. Launch is also around 1.3 T/W, so it will look pretty much like a launch in reverse….
BFS will land relatively gently, and BFR’s liftoff will also be gentle.
Development schedule
Q: With the first two cargo missions scheduled to land on Mars in 2022, what kind of development progress can we expect to see from SpaceX in the next 5 or so years leading up to the maiden flight?
Will we see BFS hops or smaller test vehicles similar to Grasshopper/F9R-Dev? Facilities being built? Propellant plant testing? etc. etc.
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A (Elon): A lot. Yes, yes, and yes.
A (Elon): Will be starting with a full-scale Ship doing short hops of a few hundred kilometers altitude and lateral distance. Those are fairly easy on the vehicle, as no heat shield is needed, we can have a large amount of reserve propellant and don’t need the high area ratio, deep space Raptor engines.
Next step will be doing orbital velocity Ship flights, which will need all of the above. Worth noting that BFS is capable of reaching orbit by itself with low payload, but having the BF Booster increases payload by more than an order of magnitude. Earth is the wrong planet for single stage to orbit. No problemo on Mars.
The first real tests of the BFR will be done by hopping a full-scale BFS “several hundred kilometers”. BFS is capable of launching itself and a tiny payload into orbit, but the utility is limited on Earth. On Mars, BFS will be far more capable as a single stage to orbit (SSTO) launch vehicle.
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- F9R-dev, used to test vertical take off and landing for Falcon 9. BFR will go through a similar program with its spaceship upper stage prior to orbital missions. (Steve Jurvetson)
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- F9R sadly suffered a software bug and self-destructed in 2014, but SpaceX had already learned most of what it needed to begin Falcon 9 recoveries. (Steve Jurvetson)
Raptor and rocket propulsion
Q: Why was Raptor thrust reduced from ~300 tons-force to ~170 tons-force?
A (Elon): We chickened out. The engine thrust dropped roughly in proportion to the vehicle mass reduction from the first IAC talk. In order to be able to land the BF Ship with an engine failure at the worst possible moment, you have to have multiple engines. The difficulty of deep throttling an engine increases in a non-linear way, so 2:1 is fairly easy, but a deep 5:1 is very hard. Granularity is also a big factor. If you just have two engines that do everything, the engine complexity is much higher and, if one fails, you’ve lost half your power. Btw, we modified the BFS design since IAC to add a third medium area ratio Raptor engine partly for that reason (lose only 1/3 thrust in engine out) and allow landings with higher payload mass for the Earth to Earth transport function.
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The Raptor engine’s maximum thrust has been decreased mainly because the size of the rocket decreased, from 12m to 9m in diameter. For redundancy’s sake, SpaceX has added a third central engine to the spaceship, versus the two engines mentioned at the 2017 IAC.
BFS’ delta “wings” from the rear of the ship. Also shown are the Raptors, with the two in the center now reportedly expanded to three engines. (SpaceX)
Q: Will the BFR autogenous pressurization system be heat exchanger based?
A (Elon): We plan to use the Incendio spell from Harry Potter
A (Elon): But, yes and probably
Autogenous pressurization refers to the method of propellant tank pressurization used. In microgravity conditions, tanks must be pressurized to keep fuel flowing to the engines and to improve the density of the fuel. While Falcon 9 currently uses high-pressure helium, ITS and now BFR have been designed to use the actual propellant in their tanks (methane and oxygen) for pressurization. This reduces the number of failure modes on BFR and improves the spaceship’s payload capabilities.
Q: Will the BFS methalox control thrusters be derived from Raptor or from SuperDraco engines?
A (Elon): The control thrusters will be closer in design to the Raptor main chamber than SuperDraco and will be pressure-fed to enable lowest possible impulse bit (no turbopump spin delay).
Like Falcon 9, BFR will need gas thrusters (RCS, reaction control system) to control its orientation (and refuel) while in microgravity conditions. While Falcon uses cold nitrogen gas thrusters, BFR will utilize the propellant it is already carrying for Raptor, methane and oxygen. Again, the goal of this is to reduce complexity.
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Q: Could you update us on the status of scaling up the Raptor prototype to the final size?
A (Elon): Thrust scaling is the easy part. Very simple to scale the dev Raptor to 170 tons.
The flight engine design is much lighter and tighter, and is extremely focused on reliability. The objective is to meet or exceed passenger airline levels of safety. If our engine is even close to a jet engine in reliability, has a flak shield to protect against a rapid unscheduled disassembly and we have more engines than the typical two of most airliners, then exceeding airline safety should be possible.
That will be especially important for point to point journeys on Earth. The advantage of getting somewhere in 30 mins by rocket instead of 15 hours by plane will be negatively affected if “but also, you might die” is on the ticket.
SpaceX’s subscale Raptor, the one seen in videos and photos of it firing, is understood to be a bit more than half the size of the operational engine described at IAC 2017. Increasing the scale of the engine is not the difficult aspect of development. Rather, optimization, weight reduction, and extreme reusability are the main sources of difficulty needed before Raptor is flight-ready. This reusability is central to the goal of reliable and rapid reuse of orbital-class rockets.
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- SpaceX revealed this stunning photo of Raptor’s first (partial) hot-fire test the night before Musk’s talk at Guadalajara. (SpaceX)
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- SpaceX’s subscale Raptor engine has completed more than 1200 seconds of testing in less than two years. (SpaceX)
Q: Can BFS vacuum-Raptors be fired at sea level pressure?
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A: The “vacuum” or high area ratio Raptors can operate at full thrust at sea level. Not recommended.
Put simply, vacuum nozzles do not like to operate in an atmosphere.
Mars communications
Q: Does SpaceX have any interest in putting more satellites in orbit around Mars (or even rockets) for internet/communications before we get feet on the ground? Or are the current 5-6 active ones we have there sufficient?
A (Elon): Yes
Q: Also will there be some form of an internet or communications link with Earth? Is SpaceX going to be in charge of putting this in or are you contracting some other companies?
A (Elon): If anyone wants to build a high bandwidth comm link to Mars, please do.
Taken side by side, this likely indicates that SpaceX will develop a high-bandwidth Mars-Earth communications link if nobody else does, but that they would logical prefer that someone else builds that infrastructure beforehand.
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Q: The concept of an internet connection on Mars is kinda awesome. You could theoretically make an internet protocol that would mirror a subset of the internet near Mars. A user would need to queue up the parts of the internet they wanted available and the servers would sync the relevant data.
A (Elon): Nerd
A (Elon): But, yes, it would make sense to strip the headers out and do a UDP-style feed with extreme compression and a CRC check to confirm the packet is good, then do a batch resend of the CRC-failed packets. Something like that. Earth to Mars is over 22 light-minutes at max distance.
A (Elon): 3 light-minutes at closest distance. So you could Snapchat, I suppose. If that’s a thing in the future.
The communication delay between Earth and Mars (at least several minutes one-way) will prevent any Martian habitats from simply integrating with Earth’s Internet. The delay will require some sort of mediation. As an example, a user on Mars could select the websites they want to browse or videos they want to watch beforehand, and they would be available between several minutes and an hour later.
SpaceX’s Starlink satellite constellation efforts could provide the company with valuable experience that can be applied around Mars. (unofficial logo by Eric Ralph)
Boring!
Q: Boring question about Mars:
A (Elon): More boring!
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Miscellaneous silliness
Q: This is one bizarre AMA so far…
A (Elon): Just wait…
Q: i feel like thats a threat. “just wait. it will get way more bizarre than that. let me finish my whiskey”
A (Elon): How did you know? I am actually drinking whiskey right now. Really.
…No comment…
All things considered, this was a wildly successful AMA. Elon clearly had a whole lot of fun, the audience got lightheartedly trolled, and SpaceX fans will undoubtedly be chewing over the technical details he elucidated for weeks to come. Special thanks are owed to the subreddit /r/SpaceX and user /u/_Rocket_, who together managed to flood the AMA with an array of intelligent, pointed, and reasonable questions, at least ten of which were answered by Musk.
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Investor's Corner
SpaceX and Nvidia team up on Musk’s orbital AI bet
SpaceX revealed a new Nvidia satellite partnership, then Musk pledged an exclusive Nvidia hardware commitment.
SpaceX and Nvidia are now working together on the hardware that will power Musk’s orbital data center ambitions. SpaceX announced on X on Tuesday that it is partnering with Nvidia to design the compute payload for Starmind AI1, the first satellite in a planned constellation built to run AI workloads directly in orbit. Each Starmind satellite will carry Nvidia’s Rubin GPUs and Vera CPUs, according to the post, which included renderings of the payload design.
The announcement landed hours before SpaceX’s first earnings call as a public company, where Musk went further, saying the company has committed to building its AI infrastructure exclusively on Nvidia hardware. “We think the Vera Rubin architecture is the best architecture. We think it’s the best AI computer, and we greatly value our close cooperation and partnership on many levels with Nvidia,” Musk told investors on the call,. “So we’re exclusive to Nvidia.”
Musk said SpaceX plans to deploy Nvidia’s Vera Rubin NVL72 rackscale system, codenamed Kyber, both on the ground and in space. He set a target of 2 gigawatts of compute capacity online by the end of this year, scaling to roughly 10 gigawatts by the end of 2027.
SpaceX’s newest Starmind will make earth data centers obsolete
Starmind has been in development since Musk confirmed the name in June, following an xAI trademark filing that tipped off the project before SpaceX made it official. The idea is massive in scope and instead of moving data down to ground based servers, satellites equipped with onboard processors and large solar arrays would compute AI workloads in orbit and beam results back to Earth. SpaceX has already filed with the FCC for a constellation of up to one million satellites to support the effort, citing constant solar power and the absence of zoning restrictions as advantages over terrestrial data centers.
The Nvidia exclusivity marks a shift in tone from just two weeks ago, when Musk was busy knocking down a report that SpaceX had ordered $52 billion worth of Nvidia GPUs through Foxconn, calling it fake news at the time. The dollar figure in that rumor may have been wrong, but the underlying direction seems correct. SpaceX’s AI division already leases Colossus compute capacity to Anthropic and Google, and Tuesday’s earnings report showed AI revenue climbing sharply as those deals ramp up.
Nvidia shares rose roughly 3% in Tuesday trading on the news, while SpaceX stock climbed nearly 9% during the day before giving back gains after hours as investors digested the earnings report’s capital spending figures.
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SpaceX (NASDAQ: SPCX) reported a beat in revenues and EBITDA in its first earnings call report while also minimizing losses as its business continues to gain momentum.
After its IPO in July, SpaceX saw some tough losses on Wall Street due to a major selloff after a delay in its 13th Starship test flight. The ship launched later that week and completed what was arguably the most successful IFT operation in the Starship program’s history.
Nevertheless, the company is continuing on and reported some encouraging financials while also promoting what appears to be a robust outlook moving forward in its Space, AI, and Connectivity divisions.
SpaceX to report first-ever earnings today: here’s what to expect
Earnings Results
- Revenues: $7.8 billion reported vs. $6.7 billion expected
- Adjusted EBITDA: $3.5 billion vs. $2 billion expected
- Net loss of $541 million, an improvement of $467 million from net loss of $1.0 billion
Additionally, CFO Bret Johnsen had these comments:
“2026 has been a momentous year so far, and the second quarter demonstrated the true power of SpaceX. Revenue growth accelerated across all our business segments and we delivered strong operating leverage, with significant margin expansion led by our new AI compute agreements. Our unparalleled leadership in launch, Starlink subscriber growth, new enterprise and government partnerships, and best-in-class AI infrastructure underscore our ability to drive meaningful scale and deliver attractive returns. As a newly public company, we are delighted to welcome our broad base of shareholders and bondholders. We ended the second quarter with $100 billion of cash, cash equivalents, and marketable securities, and $47.5 billion in backlog. This financial strength gives us substantial capacity to invest in Starship, Starlink Broadband and Mobile satellites, and our AI platform, while maintaining a disciplined long-term capital allocation framework.”
Space Business Highlights
SpaceX shared some of its biggest Space Business Highlights for Q2:
- Space revenues grew 55% sequentially and 29% year-over-year to $962 million, driven by a higher number of large customer launches and a favorable customer shift compared to the prior year
- Total costs and expenses for the Space segment were up by $389 million year-over-year, as we continued to accelerate R&D investments in our Starship program, which we believe will reduce the cost to orbit by 99% or more relative to the historical average, and unlock significant revenue potential across all business segments
- Leading launch provider for the world with 78 launches and 1,041 metric tons of mass to orbit deployed over the six months ended June 30, 2026, primarily allocated to Connectivity for the deployment of our Starlink constellation
- Starship V3 development continued to advance towards full and rapid reusability:
- Completed Starship V3’s first suborbital mission in May, Flight 12, which achieved a successful lift off from our new Starbase pad, a precision landing of Starship’s upper stage, and deployment of modified V2 Starlink satellites
- Subsequent to the second quarter, completed Starship Flight 13 in July, which achieved all flight objectives including deploying 20 production V3 satellites, demonstrating in-space relight of a Raptor engine, and executing the softest ever splashdown of Starship, providing critical views of an intact heatshield
SpaceX will report its earnings today at 4:30 P.M. EDT.
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Elon Musk issued a second pointed warning to SpaceX short sellers on Tuesday, just hours before the company was set to release its first quarterly earnings as a publicly traded firm. Responding to a report highlighting elevated short interest, Musk wrote on X: “I try to warn them, but they just double down …”
The comment came as data from S3 Partners showed roughly 95 percent of available SPCX shares to borrow were on loan, translating to about 34 percent short interest as a percentage of the float. The stock has traded under pressure since its record-breaking IPO in June 2026, declining significantly from early peaks.
I try to warn them, but they just double down … 🤷♂️
— Elon Musk (@elonmusk) August 4, 2026
This marks the second such message from Musk in under three weeks.
On July 17, amid post-IPO volatility, he stated: “The survival probability of firms who maintain a significant short position in SpaceX over time is very low.” At that time, SPCX had fallen roughly 30 percent from its peak above a $2.6 trillion valuation, with short sellers reportedly realizing gains of about $8.7 billion.
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Musk’s warning aligned with optimistic analyses projecting that Starship-driven cost reductions could enable a multi-trillion-dollar space economy through applications such as orbital solar power, asteroid mining, data centers, and Mars-related projects, positioning SpaceX as critical infrastructure.
SpaceX is scheduled to report second-quarter results after the market close later today, followed by a webcast. Analysts anticipate revenue near $6.9 billion, reflecting growth in Starlink, launch services, and AI-related segments. The earnings release precedes a major lockup expiration on August 6 that could free hundreds of millions of insider shares.
Musk has a long track record of confronting short sellers, particularly regarding Tesla, where he has argued that persistent bearish positions underestimate transformative technologies. Critics view his optimism as overly ambitious given near-term stock fluctuations, while supporters see temporary dips as opportunities in a longer-term expansion of the space economy.
As SpaceX opens its books to public scrutiny for the first time, the high short interest and Musk’s repeated cautions set the stage for heightened market attention on the results and management’s commentary.
SpaceX and Nvidia team up on Musk’s orbital AI bet
SpaceX reports beat in first earnings while minimizing losses
