SpaceX’s Announcement

A preview:

[Update a while later]

Here’s Nadia Drake’s story on the announcement. The Q and A ended up being sort of a goat rodeo.

[Update early evening, PDT]

Here’s the full presentation.

[Wednesday-morning update]

Here’s Eric Berger’s take, and Jeff Foust’s. And one from Casey Dreier at the Planetary Society.

[Update a couple minutes later]

And Chris Davenport’s.

[Update a couple more minutes later]

And Loren Grush says there’s still a lot to figure out. No kidding.

[Update another couple minutes later]

And Wayne McCandless is skeptical (with a plug of my book).

[Update a few minutes later]

Thoughts from Bob Zubrin.

[Update a while later]

Joel Achenbach says don’t pack your bags for Mars yet. And Ken Chang says Elon just needs to figure out how to pay for it. Well, I think there are other issues as well. Meanwhile, the National Space Society is gung ho (as they should be, it’s much more in line with the group’s stated objective than anything NASA is doing).

[Update a couple minutes later]

Miri Kramer’s five takeaways.

[Update late morning]

McCandless link was missing, but I fixed it.

In response to Dreier:

[Update early afternoon]

Here’s Alan Boyle’s take.

And Elon answered yesterday’s question about how they get down to the surface:

[Update a while later]

Bill Nye doesn’t buy it. But the Planetary Society doesn’t want “filthy meatbag bodies” on Mars, anyway.

Speaking of which, I’m pretty sure that this announcement will re-energize the SJWs.

[Update a while later]

An amusing take over at Wait But Why. And one of the first, but certainly not last takes on planetary protection and the Outer Space Treaty.

96 thoughts on “SpaceX’s Announcement”

  1. OK, OK, what is the deal with the Big Fine Booster? What happened to the idea of going to Mars using Falcon 9 and an on-orbit depot?

      1. Yes, but that is your plan, it is a good plan, and why is Elon Musk going with a Super STS thingy that is not such a good plan (see comments from my many distinguished friends and colleagues that follow)?

        1. It’s a matter of scale. If you’re going to send an Apollo-style expedition to Mars every few years, it hardly makes sense to build the huge vehicles that Musk talks about. Small rockets and depots are the way to go, in that case. But if you’re going to send lots and lots and lots of people, it pays to build large craft just for the purpose. And there is still a propellent-depot aspect to it: the ICT itself would be refuelled in LEO.

          1. Funny thing is he said there would be hundreds of these ships waiting in a parking orbit for the Mars’ launch season to arrive. One of the few non-retarded questions brought up the implications for vehicles with passengers.

            Musk responded with ferrying people from Earth to the parking orbit, moving passengers to the new vehicle, then the empty vehicle returning to Earth. This means there would be more launches than his slideshow implied.

  2. We knew Elon was ambitious, but that’s a monster.

    12m diameter booster, 122m height for stack. 28 million pounds thrust at takeoff. That’s… about 4x a Saturn V, depending on how you want to measure?

  3. Is there a launch escape system for this? And (minor detail) how do they get from the crew compartment’s hatch to the ground at Mars? Hope they pack a big ladder. Or they could rappel.

    1. The Spaceship part has 6 vacuum optimized Raptors ringing a cluster of three sea-level-optimized Raptors. I think these latter are the launch escape system, if required. If not required, at Mars, they seem to double as landing engines. The video shows none of these three center engines firing for Trans-Mars Injection, but only these three firing on descent at Mars.

      An Earth-sea-level-optimized Raptor will produce 684,000 lbf of thrust. Three of these, running at 20% throttle, will produce 410,000 lbf of thrust. The Spaceship is supposed to have a payload capacity of 100 tonnes to the Martian surface. That’s about 83,000 lbs in Martian gravity. I don’t know what the Spaceship’s structure weight, plus propellant load, will be upon Martian arrival, but unless it’s such that ship, residual propellant and payload weigh at least 410,000 pounds in Martian gravity, it’s going to be hoverslam time again even at minimum throttle.

      Personally, I expect the craft to be heavier than that. Elon has made quite a point about getting his spaceships back. There won’t be Martian-surface ISRU propellant production initially, so I think the Spaceship needs to land with sufficient propellant reserves to get back off Mars again and accomplish Trans-Earth Injection. Once Mars-surface ISRU is a going concern, Spaceships can be loaded with more payload and less propellant, allowing them to re-tank on Mars for the return trip.

      That would allow the price of a Mars ticket to come down somewhat from whatever the initial price will be. For a long time, that price was being spitballed by Elon as in the half-million dollar range. At IAC, he tossed out the number of $200,000. If he can manage things so as to allow that level of initial ticket pricing, he’ll get a lot more potential takers.

      If ISRU propellant production allows him to drop the ticket price to $150,000 or $100,000, it’ll be Katie bar the door. At rates like that, he’ll get huge numbers of people wanting to go who don’t necessarily intend to stay permanently, but would be happy to put in a few years there – assuming physiology permits.

      The physiology question is still the biggest “known unknown” and Elon’s IAC presentation didn’t mention it.

      1. A ‘first flight’ and an ongoing port-to-port transportation system can have differences.

        AKA: Send two minimum for the first flight, with one having its weight allotment fuel-focused, while the second has the cargo and bulk of the people.

        You can refuel the first-returner on the ground or in orbit. And the other one delivered the ISRU for the second one.

      2. $200 grand is Katie-bar-the-door. That’s a modest mortgage. A person could save up ten or twenty percent of that as a down-payment. That’s the sort of price range that brings Ken Anthony’s ideas to the forefront. If Elon can get people to Mars for that price, the first group will be spending some time surveying, marking out plots for sale. That would *not* be like the Lunar Embassy guy, at all.

        1. I don’t see $200k covering the meal and beverage service; and I’m sure there will be a few charges for checked bags.

          1. I don’t know. Musk said that it would be fun. He didn’t address meals in transit specifically, but he seemed to imply it would be like a cruise ship. He also said there would be restaurants so who knows who picks up the check.

            What the $200,000 doesn’t cover is anything someone wants to do on Mars. How much would a personal habitat, living supplies, work equipment, or whatever?

            A flophouse on Mars, wont be a fun experience.

        2. OK, so you borrow $160,000, shoot, make it $100,000, to get you there. What are you going to do on Mars that will allow you to amortize the loan, which is the only thing that will allow you to get it in the first place?

          1. If you’re a doctor, you’d open up a medical practice. If you’re a farmer, you’d farm. If there’s a million people there, then there is a whole economy right there.

      3. For a round trip, parking supplies in Mars orbit for the return trip can save a lot of propellant mass on the lander. A tether system anchored to Phobos is also attractive if you’re making several round trips.

  4. Just got up at 4:30 am local to watch.
    Interesting that the ship itself is capable of SSTO with minimal payload.
    Lots of unknowns. No artificial gravity in transit.
    Really, really need a gravity lab in LEO.

  5. Really!? All your eggs in one BFR basket? Doesn’t seem smart. Lots of smaller flights to deliver people, stuff, habitat, etc. in smaller bundles seems smarter. And cheaper.

    1. That’s why it is great that we have Blue Origin. Didn’t you see the New Glenn announcement? Competition and different approaches are a GOOD thing. I’m not sure why people seem to think that SpaceX must have a LV for every market.

    2. “Small” is a relative term. Compared to the task of sending thousands of people to Mars at each launch window, the BFR and ITS are small.

    3. Musk was talking of having a fleet of such vehicles leaving en masse every transfer window, like the fleet from Battlestar Galactica. He also mentioned that SpaceX is right now producing Merlin engines at a rate of 300 per year so they’re not worried about being able to produce enough Raptors. If I recalled that correctly, then SpaceX is producing more Merlins per year than the entire stock of RD-180s, and more than they themselves can use in a year. That should give companies like P&W something to think about.

  6. OK, so big reveal of a BFS to go with the BFR. And on-orbit refueling to achieve Mars injection. But what we are a little light on is Mars surface infra-structure. I’ve seen more from Ken on this than anything Elon presented today. If only transport were the only issue. But I suppose a lot of one-way BFS’s as cargo transports will help. We just need to define what that needs to be.

    What did surprise me a bit is how luxurious Elon describes the BFS. If your focus is strictly planetary is that really necessary? I suppose if you want to be able to visit destinations other than Mars that makes sense, but if Mars is the focus is that really necessary? I’m thinking the Pilgrims didn’t wait to come to North American until the Queen Mary was built…

    Yes, most glaring omission, artificial gravity to support longish transport missions. But if you are cutting transit times drastically with the infinite improbability drive, ok, I get that. Just show me the drive first!

    I don’t think a “fun” ride on a BFS comes for free and one should consider at the expense of what else?

    This really does look like Collier’s Goes To Mars.

    1. But what we are a little light on is Mars surface infra-structure.

      Except that Musk is relying on capitalism and individuality to do this rather than planning out an economy, every single participant, what those participants will do, and how they will do it. He said they were working on the transportation and that other people and groups would work out habitats and things like that.

      How do you express the benefits of capitalism as opposed to planned and controlled societies? Its challenging because a lot of it relies on things that can’t be known right at this moment.

      The infrastructure he did talk about were solar cells to run his fuel plant. Did you notice how he started to say lots of nuclear then pulled back and said solar, geothermal, and then in a very political way brought nuclear back in?

      It would be nice to know more about the infrastructure specifically needed for the SpaceX part of things, the fueling and launch from Mars.

      1. > Did you notice how he started to say lots of nuclear then pulled back and said solar, geothermal, and then in a very political way brought nuclear back in?

        This was the one prediction that I made about today’s announcement that was spot on. Talk up the solar, don’t mention the nuclear. Even so, he let its slip a couple of times.

    2. This thing, like many other grand plans such as the Von Braun Marsprojekt, is Democracy, Whisky, Sexy, but there are many undemocratic actions involving neither distilled spirits or human lusts that could get us there quicker?

      OK, propellant depots — doesn’t that need some on-orbit experiments on the storage and transfer of propellant to move forward, experiments that are magic-free small plans that don’t get anyone excited all that much?

      Similarly, electric propulsion to get the delta-V to shorten the trip — electric propulsion has been around for a very long time. But electric propulsion requires a 2nd Law of Thermodynamics power source that needs to reject heat some other way apart from the expansion and expulsion of rocket exhaust. The Stefan-Boltzmann 4th power law is a cruel constraint, and it takes a lot of surface area to expel a lot of heat at anything close to a cold temperature.

      What about solar cells, you say (they are in the video), and yes, what about them? These puppies still need to radiate that portion of absorbed energy not converted to hole-electron pairs, and they do this by being — large.

      So the keys to interplanetary travel may not be in worrying about the BFR and the BFS but rather in figuring out to store and pump propellant on orbit? The key to high delta-V interplanetary journeys is electric propulsion, yes (gets around the thermal limits of materials in stuff like nuclear thermal), but the key to that is a better space radiator — there are ideas “out there” like showers and fountains that create enormous radiating area with much less weight?

    3. > What did surprise me a bit is how luxurious Elon describes the BFS.

      Me too. I would think that life on Mars would involve some big sacrifices, like never again being able to step out the door for a breath of fresh air. If people need 1st-class comfort and amusement for the 100-day journey to Mars, how are the ever going to adapt to the lifelong limitations of an early Martian colony?

      Maybe it’s just a trick to make them all pine to come back to Earth: Musk will be able to charge whatever he wants :):):)

  7. This is very impressive and I hope Elon actually builds it, but I continue to ask the question I have always asked: what are the colonists going to do on Mars (or the moon for that matter) to pay for the transport, for all the supplies and equipment they are going to have to take with them, and all of the additional supplies and equipment they will continue to need just to survive? Solar, or nuclear, power systems, pressure suits, and, for that matter, such mundane items as electric cook stoves, can not be made with stone knives and bear skins, especially when there are no bears.

    1. People are the market.

      Right now, there are no people that need anything on Mars. Once there are people there, they will need things. At first this will come from Earth but later it will come from the colonists themselves. That’s why Musk was talking about needing a certain number of people there.

      Markets will spring up wherever there are humans. Even if it is just two scientists, they will trade goods and services. The more people that are there, the more opportunities for trade exist. What is to stop a person doing geology on Mars from also starting a business on their off time? Maybe this business services other people on Mars and/or it services people on Earth.

      The pitfall to avoid is “free” things from Earth that could prevent a Martian entrepreneur from selling a product. Poverty Incorporated is a good illustration of how this works.

        1. Completely irreverent. Trade will start on landing when new colonists meet old and continue from there.

          There will be trade between planets eventually, but the only safe bet is to assume none (other than the personal property of new colonists.)

          1. No. Let’s say that the first group of colonists rip a space suit and need a new one. Space suits are expensive, transporting them to Mars isn’t free. These colonists do represent a market, but in order to supply that market, they have to produce new wealth to trade for that space suit. Even if there were pure refined gold just sitting there waiting to be scooped into bins, you could not bring it back to earth and sell it for a profit. How are the colonists going to pay for that space suit, or anything else they need?

        2. They will trade rocks.

          At first any rocks will be valuable on Earth, but after a while most of the trade will probably concentrate on flint, which is useful for making tools.

          Martians could also corner the market on dry ice.

          1. Do you really think it would be cheaper to go all the way to Mars for dry ice than to simply make it here?
            How many people do you think would really be both willing and able to spend thousands of dollars for an ounce of nondescript rock, just because it came from Mars?

        3. Rand asked,
          The question will be: What will Martians have that earthlings will be willing to trade for?

          I have a few guesses.

          Raw materials; *if* there’s a demand (by that time) for raw materials (including fuel) in LEO and GEO, it’s easier (in delta/v) to get there from Mars’ surface than from Earth’s. This would be doubly true if you have transport spacecraft coming back from Mars with surplus capacity. Also, if there are significant manned space stations in LEO and GEO by then, food.

          Tourism. It’s the ultimate adventure destination.

          Research opportunities; I’m sure there are plenty of scientists who would love to do research on Mars, and at a few million per head, it’s within the means of a lot of organizations.

          Exotic products – Martian jewelry, etc.

          Satellites; it’s a lot easier to launch a commsat to Earth’s GEO from Mars than from Earth. (though this would take a large in-situ tech base).

          I’m skeptical on the economics, but I do see how it might be possible. (I also think that making the case economically is every bit as important as the design of the transport system).

          My analogy would be; what was the economic basis for the first North American European settlements? They, too, were rather dubious and speculative. (As well as very high risk)

          1. Further to the point of research opportunities: if transport ships are coming back with excess capacity, some of that could be Martian rock. What geologist on Earth would not want to have access to that?

            I don’t even know how to put a price tag on that. And it wouldn’t be like trade in a precious metal, where large amounts would flood a market. Every rock would be unique. Two rocks, both from Valles Marineris, wouldn’t lose value if a third rock from the same valley was sampled 200 km away, higher up the cliff. Imagine the value of ground truth from samples taken from all over the planet.

          2. Gold, silver, tobacco and sugar could all be shipped back to Europe and sold for a profit. If there were ingots of pure, refined gold sitting on the Martian surface (no doubt left there by Jim Hoagland’s aliens) you could not ship it back and sell it at a profit.

          3. Michael, what part of they don’t have to export do you not understand?

            Exports only matter if it is required to pay the ticket price. Elon intends to get the price low enough that, that is not the case.

            Did nobody understand Bill Whittle?

          1. There are some economic reasons but there are also ideological, emotional, aspirational, among other reasons.

            Musk is providing the transportation. Its up to individuals and groups to come up with their own reasons. That is the beauty of capitalism. There isn’t a single reason, there are many reasons.

            We don’t know, we can’t know, what all of these reasons are or which motivations will lead to success. But we do know that creativity, ingenuity, and entrepreneurship are human traits.

            Musk is saying, give humanity the opportunity and let’s see what they do with it.

        4. Anything that can be done over the internet, is a start. Financial services, programming, consulting, ect.

          Researchers are likely to be some of the first inhabitants. They can sell their findings or they can contract their services out to those on Earth.

          Maybe someone will seek funding from Earthlings to start a business that provides things to Martians. Meaning that people on Earth will profit without any transfer of physical goods from Mars to Earth.

          I wouldn’t be surprised if George Turner is right and they sell rocks to Earth. Art has value. Martian art would be a big status symbol. Maybe one of those art pieces will even be a stone axe made from Martian rock, a 3D printed shaft, and cordage from plants grown on Mars.

          Once there are enough people there, there will be a market. That market will interact with Earth. Musk realizes this and that is why he is planning for thousands to go at once.

          You could relate it to starting a brewery. What volume would need to be produced to cover the costs of running the business? A brewery that can produce that volume is what is needed to be built.

          1. Given the fact that the spaceships return mostly empty, marginal shipping costs could make even crappy exports profitable, like glass ashtrays stamped “Made on Mars”.

  8. I only have a single word to describe this: NUTS.

    He seems to be fixated that the ship must carry 100 people. Why? The DC-3 carried 32 passengers. Look at the crew complements of the ships Columbus used. 40 in the largest ship and around 24 in the others.

    This ship design makes the N-1 look simple in comparison. Then the talk that you manufacture it somewhere else, in multiple states, and assemble near the launch site… Where did I hear this before… Right. The N-1. They better build someplace to test the first stage close to the launch site.

    Then building the tanks out of carbon fiber composite and make them self-pressurizing. Well I think the self-pressurization idea is great but carbon fiber is not exactly the easiest thing to repair. He did say he expected to reuse the rocket right?

    The transfer vehicle seems to me like a pipe dream. I also think it would make more sense to have a couple of orbital stations near Earth and Mars and use a transfer vehicle in between. Using chemical propulsion for going between Earth and Mars also seems kind of expensive.

    It was interesting to hear about the Raptor engine specs and the proposed launch vehicle architecture like the solutions for the fuel tanks. But I’m more interested to learn about the rocket they didn’t talk about. Because I’m not expecting SpaceX have nothing in between Falcon 9 and this rocket.

    1. Godzilla said;

      Then the talk that you manufacture it somewhere else, in multiple states, and assemble near the launch site… Where did I hear this before…

      Yes, multi point assembly sources for a very complex vehicle… just like Airbus does it.

      That part, I have no problem seeing as being feasible.

      My concerns are, first, economics; this will be paid for how, exactly? I’d feel a lot more comfortable if they had also shown a non-Mars variant of the booster, on that could be used for revenue (such as launching payloads to earth orbit). Perhaps a shuttle-style cargo bay on a version of that tanker? Otherwise, if the whole infrastructure is Mars-dedicated, it creates a massive fiscal barrier up front vs. a launch system that has its R&D at least partially amortized by nearer-term revenue. And, it does have revenue potential; the cost per pound to orbit should be exceedingly low. Sure, it’s oversized for the market, but with a low enough cost per payload, it’s usable.

      As for the interplanetary spacecraft, I have MAJOR concerns. First and foremost, just how, exactly, will you store the subcooled LOX and also methane needed for landing for the voyage? That stuff requiures cooling, as does the spacecraft. A quick look at ISS shows that its cooling system (radiators, etc) outmasses its solar arrays. Yet, nothing about this is shown or mentioned in the SpaceX presentation.
      Also, looking at the demo vid, it appears the extended solar arrays are roughly on par with ISS in area. How in any conceivable way does that run life support (and cooling!) for 100 people?
      And further, to go from Mars surface to Earth requires a delta/v of about 4.2 kps. Will the spacecraft have that kind of delta/v, given the huge amount of mass inherent in a manned craft? Same issue applies for LEO to Mars TMI burn, especially for fast transfer orbits.

      I have grave doubts the spacecraft is viable on a mass-fraction basis. What makes me the most doubtful is that things like cooling weren’t even mentioned.

      I very much hope I’m wrong.

      1. Yes, multi point assembly sources for a very complex vehicle… just like Airbus does it.

        They do it because of subsidies and politics. The Airbus leadership has said more than once they would rather manufacture everything in Toulouse to prevent something like the A380 debacle from happening all over again. It makes the airplanes more expensive to manufacture and increases the chances of integration issues on final assembly. But the politicians (particularly the German politicians) won’t allow moving everything to Toulouse.

        how, exactly, will you store the subcooled LOX and also methane needed for landing for the voyage?

        You can probably Google “space storable propellants methane” and find your answer right there.

        The whole design of the upper stage looks kinda weird to me. But then again remember the difference between the early Dragon mockups and Dragon V2.0… Little is left.

        1. I’m somewhat familiar with the design of prop depots – enough to know that there are significant differences between prop depots and a spacecraft (insulation and cooling being just two). There’s also the issue of subcooling; you don’t just have to store the prop, you need to keep it subcooled. The reason, reportedly, is the engines; SpaceX prefers subcooling for Raptor to avoid cavitation issues in the turbopumps. This likely means Raptor requires subcooled prop (Just keeping them liquid won’t do). That makes it harder.

          Also making it harder is having a manned spacecraft as part of what is, functionally, a long term prop depot. The heat soak issue is just one.

          Agreed on the upper stage design.

      2. My concerns are, first, economics; this will be paid for how, exactly? I’d feel a lot more comfortable if they had also shown a non-Mars variant of the booster, on that could be used for revenue (such as launching payloads to earth orbit).

        Mike Borgelt has some good ideas below.

        Musk was saying that the more the booster flies the cheaper any one launch is but also implied that while launches would be taking place between launch seasons, they would all be for Mars missions.

        Isn’t this a case for supporting activities in cis-lunar space? They could get more launches in, assuming they had customers, that would then lower the costs of going to Mars a little bit.

        Would a cis-lunar variant require anything more major than software and operations tweaks?

  9. The presentation was cool to watch. It is a very ambitious plan but also very long term when talking 40-100 years to move enough people.

    Musk didn’t talk about some of the unknowns too much but he did acknowledge them. It came off as things were in flux a little bit and that was OK. The underpants gnome reference was the best part.

    It is impossible to know everything with specificity and it is wise for Musk to focus on the contribution he wants to make. If he is right, it will allow other people to build on his success.

    Some of those questions though… Globally televised event with Elon Musk, you should put in some effort and be respectful.

    1. He said next year? But I’m not certain why to bother with something with its added complexity (27 first stage engines) when AFAIK Raptor is in full scale testing right now. They probably could make a Falcon 9 with Raptor in like a couple of years except it would only have two engines. So a Falcon 9 Heavy with that would have like 6 engines.

      1. The idea persists that more engines are a “Bad thing”, with “n-1” becoming a chant from some people in the last 24 hours. Yet, it is the Falcon stage with a single engine that has given their worst and most persistent problems. At the same time, at least one mission was saved by the redundancy of 9 engines in the first stage. In fact, the major advantage of switching to Raptor, IMHO, is the ability to do away with the COPV Helium that *has* been Falcon 9’s major operational problem.

        As long as system-wide vibration problems, such as plagued the N-1, are avoided, and reusability is not affected, then the disadvantages of more engines seem to be less than their advantages, at the numbers presently proposed and used. In particular, since ITS is getting only 5% of the present engineering resources of SpaceX, and those resource restraints will only tighten, it seems that re-shifting those resources, yet again, will both slow progress *and* make future flights less safe.

  10. Reading the comments at Drake’s article. It is imperative that government not be relied on. Too many people want stop people on Mars from happening. The more this effort is in private hands, the less influence these people have.

    Even then, many of these people are so emotional that they will try and use government to prevent people from pursuing interests that they disagree with regardless of who is funding it.

      1. I agree but consider these are not people who say, “I don’t care what they do as long as I am not paying for it.”

        These are people who see humans going to Mars as morally abhorrent and willing to use any tactic to stop it,

        We can see from recent history that some of these people feel justified and obligated to use violence as a means to change behavior they don’t like. There are a lot of highly educated people who work in the sciences who think this way too.

  11. It obviously won’t work. NASA has already concluded that refueling in orbit is impractical, impossible, high-risk, and every other negative buzz phrase one can imagine.

    And that’s NASA. If you can’t believe them, who can you believe?

    1. I look forward to the NASA-approved future where, down through the millenia, our descendants in space never transfer fluids from one tank to another. This can only be done on Earth for some reason.

  12. Actually, I calculate a cost per passenger of about $164,000. That is based on the cost of an Apollo/Saturn launch in 1969 ($185 M), scaled by inflation, scaled linearly by vehicle size (and vehicle size/cost relations are actually more favorable than linear), and scaled by the current quoted saving for a recovered stage 1 Falcon 9 launch ($40 million vs. $62 million). You divide that by 100 people, and it comes out to $164,000. I can afford that, and would.

      1. It isn’t just America. A Russian investor just bought Sea Launch, and is going to restart operations. Reaction Engines keeps plugging away on Skylon and the SABRE engine, and they’ll probably have first flight before SLS. Virgin Galactic is flying again. Hopefully even more companies join in this game – I’d love to see KellySpace revived, being towed by a White Knight.

  13. So lets see, this thing needs 3.3Km/s to escape LEO and about 5.0 km/s to land on Mars although there will be some aero braking (some of the real rocket engineers here will know). Elon says it is an Earth SSTO (8Km/sec) without much payload and has to escape from Mars to return to Earth so ISRU will be compulsory.
    Seems to me it may be able to do LEO to surface of Moon and back to Earth re-entry without refueling at Moon but with reduced payload.
    I’d be building a scale model of the ship and putting it on top of a Falcon 9 for testing. May even be useful as an operational vehicle.

    1. To be fair I imagine that they are contemplating making a recoverable upper stage for F9/FH along these same lines. Developing a reusable CH4/LOX upper stage does look like the next thing they should do after getting Falcon Heavy working.

    1. The Raptor supposedly has deeper throttling than the Merlin. I don’t know the exact numbers but it looks pretty clear to me you can make a reusable with less engines than this Frankenrocket.

      1. I think the Raptor can throttle down to 20%. With (was it 9?) engines on the transport that would effectively be about <3%?

        1. Is that 20 at sea level or altitude? As long as you’re using a conventional bell nozzle minimum throttle is limited by flow separation when exhaust plane pressure falls much below ambient.

  14. Twitter police is breaking out in ‘dont you dare use the word colonize’ right about now. Yup, prominent planetary science tweeters are in convulsions

    1. It’s actually quite reasonable that they are objecting to the word “colonize”. It is, after all, disrespectful and offensive to the natives*, who are the intellectual peers of the aforementioned twitter police/trigger warning crowd.

      *Mars does have natives. They are called rocks.

    2. These people produce almost nothing of value and survive by taking money from people who do. Do they appreciate the nature of that relationship? Nope.

      1. Well, you are actually wrong in that. Some of the prominent planetary scientists there do produce very valuable analysis and hypotheses about nature of our universe. It’s just that they are fundamentally against us inhabiting most of that universe

        1. The value of that is rather nebulous.

          I think its an important endeavour but it isn’t self funding or making the taxpayer’s life any easier.

          A lot of these planetary scientist types come off as rather entitled and with a lack of respect for the relationship that makes their lifestyle possible.

  15. Based on the weights and Isp provided, the upper stage should only have something like 5 km/sec delta-V. If so, that is just barely enough to do interplanetary Earth-mars transfer on the long-lobes of the porkchop plot. I don’t know how you do the short ones with only 5.4 km/sec, much less Earth escape, mars entry, mars landing.

    I’m still crunching the numbers though…

    1. Well, that was assuming the stated 450 Mg of cargo. If you only take 100 Mg, or no cargo, the delta-V is 8.1 or 9.8 km/sec respectively.

      Earth escape: 3.2 km/sec dV.
      Earth-Mars transfer (assuming that you are going to try to dump several km/sec with aerobraking only at mars): 3.6 km/sec, but that is assuming that you are taking 200 days to transfer.

      1. Thanks for the numbers!

        One question though; why assume LEO as a departure point? My guess has always been an elliptical orbit (sub GEO); that lowers the delta/v for TMI significantly. In fact, I think it’s the only possible way SpaceX’s figures on transit time could work, given the apparent delta/v of the vehicle (which also needs some prop for landing).

        1. Pretty much in line with Zubrin’s thoughts as well. If you keep the TMI booster closer to Earth and inject only the piece needed to land on Mars you get more opportunities to send things to Mars using in-orbit refueling rather than once every 4 years, waiting for ships to return. Makes a lot of sense, esp. once you have ISRU up and going you could do the same going the other way. Also Z notes you could do this with the existing F9H, no BFR/BFS (and other BFBS lol) needed.

          That seems far more feasible in the short term than waiting for a BFS.

          I was also wondering about the possibility of actually constructing a return vehicle on-site? Assuming a lot of raw material and heavy equipment had been sent ahead and was already available on the surface? Stack a couple of Red Dragons to form a two-stage return vehicle?

          Note to Rand: Wayne McCandless response link is missing.

        2. My guess has always been an elliptical orbit (sub GEO);

          Van Allen belts? My understanding is that GEO isn’t very far above them, and I don’t think you want to pass through them on every orbit.

          1. With proper radiation shielding that would be fine, but Musk’s plan doesn’t have serious radiation shielding.

            Ideally you’d put the transfer ship into a very elliptical orbit, then refuel it, and then do the main departure burn at perigee to get the maximum Oberth effect.

            But that implies multiple trips all the way through the Van Allen belt.

            The best case I can see is to mate with the depot in LEO, boost to a high orbit while still mated so that the transfer ship can top off, and then separate from the fuel depot prior to perigee to make the TMI burn, while the fuel depot stage performs a burn to drop back into LEO, or even re-enters.

      2. I’ve been crunching numbers. I still can’t figure out how the travel times indicated for each window are arrived at. Type I trajectories are usually around 200 days. Type II trajectories are ~300 days. The delta-V I’m getting for going much below 100 days is on the order of 20+ kps just for the Earth to Mars-Transfer orbit burn.

        I’ll have to play with my ranges for departure/arrival, but I’m looking at a 5 year period – should be more than Earth-Mars synodic period.

    1. Let’s hope not. It wasn’t just you. I was also getting weird Howard Hughes vibes when I saw the proposed rocket. The Spruce Goose kept popping up in my mind…

  16. I dropped out of the Planetary Society and stopped financially supporting them years ago. Not long after Carl Sagan passed away.

    And as time has passed its been looking like a better and better decision.

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