SpaceX’s Musk Does Reddit AMA, Talks Rockets, Mars, and Influences

SpaceX CEO Elon Musk with one of his company's Falcon-9 rockets. Photo Credit: SpaceX
SpaceX CEO Elon Musk with one of his company’s Falcon-9 rockets. Photo Credit: SpaceX

Just hours before SpaceX’s fifth cargo mission (CRS-5) was due to be launched to the International Space Station (ISS), the company’s CEO and CTO was up late in Cape Canaveral answering fans’ questions on Reddit, the social networking website touted as “the front page of the Internet.” During a Reddit “Ask Me Anything” feature, Musk discussed SpaceX’s future, including the Mars Colonial Transporter (MCT) project meant to take humans to Mars and back to Earth, the company’s attempt to land the first stage of its Falcon 9 v1.1 on a floating platform in the Atlantic Ocean, his influences in life, and inspiration.

User “EchoLogic” asked three questions on behalf of the SpaceX fan community, encompassing the Falcon Heavy, Mars colonization, and spacesuit technology. When asked: “Some have speculated that at stage separation the Falcon Heavy center core is too far downrange and traveling too fast to be feasibly returned to the launch site. Could you go into some detail on whether you plan to use barge landings permanently for this core, expend it depending on the mission, or take the payload loss and boost back to the launch site?” Musk responded: “Yes, the Falcon Heavy center core is seriously hauling a** at stage separation. We can bring it back to the launch site, but the boost back penalty is significant. If we also have to the plane change for geo missions from Cape inclination (28.5 deg) to equatorial, then a downrange platform landing is needed.”

SpaceX’s head also dropped news about the development of MCT. Musk added in response to a question concerning MCT: “The Mars transport system will be a completely new architecture. [I] am hoping to present that towards the end of this year. Good thing we didn’t do it sooner, as we have learned a huge amount from Falcon and Dragon.” Musk stated later: “Goal is 100 metric tons of useful payload to the surface of Mars. This obviously requires a very big spaceship and booster system.” Discussing a spacesuit project he stated: “Our spacesuit design is finally coming together and will also be unveiled later this year. We are putting a lot of effort into design esthetics, not just utility. It needs to both look like a 21st century spacesuit and work well. Really difficult to achieve both.”

Bearing the CRS-5 Dragon cargo craft within its nose, the Falcon 9 v1.1 stands patiently to execute the United States' first mission of 2015. Photo Credit: AmericaSpace
Bearing the CRS-5 Dragon cargo craft within its nose, the Falcon 9 v1.1 stands patiently to execute the United States’ first mission of 2015. Photo Credit: AmericaSpace

Enthusiasm is still running high about SpaceX’s attempt to land its first stage on a floating barge, scheduled to occur Friday during the next CRS-5 launch attempt. One Redditor asked: “How will you secure the first stage of the Falcon 9 to the barge when it lands? Gravity or some mechanism?” To which Musk responded: “Mostly gravity. The center of gravity is pretty low for the booster, as all the engines and residual propellant is at the bottom. We are going to weld steel shoes over the landing feet as a precautionary measure.”

User “AvenueEvergreen” asked: “Previously, you’ve stated that you estimate a 50% probability of success with the attempted landing on the automated spaceport drone ship tomorrow. Can you discuss the factors that were considered to make that estimation? In addition, can you talk more about the grid fins that will be flying tomorrow? How do they compare to maneuvering with cold-gas thrusters?” Musk responded with humor: “I pretty much made that up. I have no idea… The grid fins are super important for landing with precision. The aerodynamic forces are way too strong for the nitrogen thrusters. In particular, achieving pitch trim is hopeless. Our atmosphere is like molasses at Mach 4!” When asked how he’d celebrate if the barge landing was a success, he answered, “Party at Cocoa Beach!”

Perhaps the most illuminating answer from Musk involved one of his influences growing up: a school principal. Danielle Miller asked: “I’m a teacher, and I always wonder what I can do to help my students achieve big things. What’s something your teachers did for you while you were in school that helped to encourage your ideas and thinking? Or, if they didn’t, what’s something they could have done better?” Musk candidly related: “The best teacher I ever had was my elementary school principal. Our math teacher quit for some reason and he decided to sub in himself for math and accelerate the syllabus by a year. We had to work like the house was on fire for the first half of the lesson and do extra homework, but then we got to hear stories of when he was a soldier in WWII. If you didn’t do the work, you didn’t get to hear the stories. Everybody did the work.”

In spaceflight, encountering adversity is the norm, not an exception; last year’s events in late October (an Antares rocket failure, followed by the crash of Virgin Galactic’s SpaceShipTwo) underscored that “it is rocket science.” One user briefly touched on the setbacks experienced in this field by asking: “You seem to have had to deal with a tremendous amount of adversity in a few of your ventures. Do you have any advice for those dealing with seemingly insurmountable adversity?” Musk replied, “There is a great quote by Churchill: ‘If you’re going through hell, keep going.’” On Friday, SpaceX helmed by Musk will “keep going” with CRS-5’s next launch attempt planned at 5:09 a.m.


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  1. I am thinking that with the F9R, DragonV2 (reusability) and cooperation with Bigelow aerospace and Ad Astra Vasmir rocket all the pieces exist for a Mars trip at under $10B…

  2. “Goal is 100 metric tons of useful payload to the surface of Mars. This obviously requires a very big spaceship and booster system.”

    It certainly does. Does anybody know what the LEO payload of this vehicle would supposedly be?

    • Joe,
      Why wouldn’t he just use several trips with F9R with a combination of 5 DV2 and combine 3 BA330s together and power it all with an ION Thuster??? I don’t think he needs a massive new architecture if he has reuseable systems does he?

      • Tracy,

        Because that is not what he is saying. He is saying a single booster will place 100 metric tons on the Martian Surface.

        Remember that means the total vehicle as it leaves Earth will have to be much heavier. To do that with F9’s (reusable or otherwise) would require not several, but many launches and extensive on orbit assembly. A significantly bigger job than the ISS assembly for each Mars Mission.

        • 100 tons payload on Mars surface from a single Earth launch is roughly (BOTE)a fully fueled Saturn 5 in LEO. Times 20+ ground GLOW. I think it is safe to call this one busted.

          100 tons of payload in LEO refueling from prepositioned depots in LEO and eccentric Lunar orbit is far more feasible with no orbital assembly required. Refuel in LEO and then TLI burn. Refuel in eccentric lunar orbit and do a very short burn to TEI. Strong burn at perigee for a fast track TMI. Use empty tanks for elbow room during the voyage.

          • I could start an interesting discussion by asking about the source of the propellant for the “prepositioned depots” (especially the one in lunar orbit), but that would be off topic since that is not what Musk is proposing.

            The irony should not be missed that for years SpaceX supporters have told HLV proponents that SpaceX was proving that HLV’s were unnecessary.

            Those proponents were generally talking about a maximum of 150 metric tons to LEO and were ridiculed as dinosaurs and members of an Apollo Cargo Cult.

            Now SpaceX is proposing some sort of Super HLV that would literally dwarf any previous proposals by more than an order of magnitude.

            • Joe and John,
              Wouldn’t a 100 tons to LEO in one shot require 1000 ton booster or is that a 10,000 ton booster with existing technology which I am wondering if the exhaust alone destroy half a county in Florida? Wouldn’t that be like launching the Empire State Building ???

              • Tracy,

                100 Tons to LEO is not an unreasonable number the Saturn 5 had a 125+ Ton to LEO payload and did not sink Florida.

                The problem is that the 100 metric tons that Musk is quoting is to be delivered (apparently by chemical only propulsion) not to LEO, but to the Martian surface.

                As an example in Constellation Systems it was to take at least five Ares 5 launches to deliver a substantially smaller payload to Mars. That would be a minimum of 750 Metric Tons for a much smaller lander.

                I suspect John was being facetious in his statement that “100 tons payload on Mars surface from a single Earth launch is roughly (BOTE)a fully fueled Saturn 5 in LEO” (that would be about 3,000 Metric Tons), but that is probably pretty close to accurate.

                • Joe,
                  Yes to the surface of Mars not LEO …Still it would take a rocket 24 times the size of a Saturn 5 to deliver 100 tons to the surface of Mars at 3000 tons (fully fueled S5) divided by 125 Tons = 24…Wouldn’t that be the size of the Empire State Building??? It such a Rocket feasiable?

                  • “Wouldn’t that be the size of the Empire State Building???”

                    Lets just say it would be a really, really, really big rocket.

                    “It such a Rocket feasiable?”

                    I am an engineer and am therefore reluctant to say something cannot be done, however it does not seem likely that such a booster would be practical on an operational basis.

                • suspect John was being facetious in his statement that “100 tons payload on Mars surface from a single Earth launch is roughly (BOTE)a fully fueled Saturn 5 in LEO” (that would be about 3,000 Metric Tons), but that is probably pretty close to accurate.

                  Even without running the actual rocket equation, V from LEO to Martian surface is very close to that from the ground to LEO. Saturn 5 is shorthand that most people can grasp immediately as opposed to a freestanding number like 2,914 tons.

                  We may not share the definition of heavy lift, or the reasons for and against. We also don’t seem to share definitions of the business case. That’s too bad as anything from battleships to toothpicks that doesn’t close a business case will only last as long it receives charity.

                  • As I said your Saturn 5 reference (even if placed in colloquial terms)is basically accurate.

                    Heavy Lift has become a term with no real meaning due to the political nature of most discussions on the internet. My own opinion (based on experience in EVA assembly) is that a roughly 100 Ton payload mass is as close as you will currently get to optimal. If that is called Heavy Lift (or not)is beside the point.

                    Business case (at least to me) is something that can be sold to a lender to get the money to try to meet an already existing commercial market. That is sadly not (at least to me) currently the case with any BEO activity. As of now you either want to do it or you do not and that is a decision that must be made by political entities (for the record, I do not like that any better than you seem to – but that does not make it any less true).

                    No personal offense intended in any of this.

                    • iPhone comment short. Cost benefit ratio is probably a better term. Going to your sons ball game has a cost and benefit in the sense I am using the term. It’s not always money.

            • I would be one of the people that think heavy lift does not make a business case at this time. SpaceX proposing it makes no difference.

              • I do not believe in the SpaceX behemoth either.

                A roughly 100 Ton payload capable vehicle is another matter, if you are planning operations beyond LEO.

                As to arguing the subject of “a business case” for a market yet to be opened, I will leave that to you and Mr. Musk.

        • Joe, Re: previous discussion on whether or not barge landings would be required for reusing the first stage.

          Florida Today, this week had an article stating that SpaceX was negotiating with the USAF and the two expect to finalize the lease on LC-13 at Cape Canaveral Air Force Station by the end of the month, to be used as a landing pad for Falcon 9R first stages.

          On Reddit Musk answered a question on the limitations of boost-back to land at the launch point, and said that it would just be the center core of a Falcon Heavy on a GTO launch which has higher velocity at MECO and needs to make an angular adjustment burn, where a barge landing would be needed for downrange recovery.

          • Thanks for the information (seriously).

            I will believe it when (and if)it actually happens.

            Musk also says he is going to deliver 100 people to Mars with the launch of a single Super HLV.

      • Also in the Reddit session, another question Musk answered another question about propulsion favoring chemical engines for the whole trip as the most effective.

        A new, much larger reusable architecture is entirely the direction SpaceX is planning for Mars.

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