45

There are several compelling engineering and design reasons why a bigger spaceship makes sense and several reasons why making a mini-starship does not make sense for SpaceX specifically (and their vision). First and foremost, Elon Musk has made it clear that his goal for the company and the future isn't to provide cheap satellite launch capabilities, it's ...


44

Musk is creating a Starship "production line", because obviously, he wants a lot of Starships. This aligns with the company's goal of "making humanity a multi-planetary species". As for "where is the market?": It doesn't exist yet. Currently, SpaceX's attitude towards space is "build it and they will come". Many large scale investment organizations ...


38

In my experience, I've noticed that SpaceX uses a lot of temporary components until such temporary components need to actually be tested. Since the legs of MK1, MK2, and most probably MK3 will never see uneven soils rather than concrete landing pads, they will most likely just have simple legs. After a few successes with MK3, we should start seeing much more ...


31

In the question you mention about why Falcon 9 uses four legs to land instead of three, there are multiple great answers. One of them by @David Hammen states that: "Another factor is that the Falcon has nine engines, one in the center and the other eight around it in an octagonal or square-like arrangement. The bottom part of the thruster reflects ...


27

Starship is a 9 meter wide vehicle. The first stage (Super Heavy) will be mounting 35 or 38 or some other number in that range of sea level engines. As you can imagine that will take at least three separate rings of engines. 6 in the center, then two more rings with the rest. The Starship is the same diameter as Super Heavy, and the inner ring will be ...


23

While this seems lightly ill conceived, it actually makes sense. Super Heavy is going to be very large, as these things go. 70m tall, 9m wide, and while not very dense, still quite heavy. Not very easy to move around. The plan is to land close by to make moving it back to the launch pad easier. Original plan was notionally to land back on the launch ...


20

It's pretty simple: Beresheet has a dry mass of 150 kg. Starship has a dry mass of 120 t. So even though Super Heavy is 10 times as powerful as Falcon 9, that's nowhere near enough to make both situations similar – even without needing also fuel for the return.


19

Bob Zubrin, of Mars Direct fame, has been critical of the SpaceX Mars plan. He suggests that it makes no sense to send a full Starship too Mars, instead use it to launch the Mars vehicle and just use Starship to bring payload and fuel. Most of the concern revolves around the fact each Starship sent to Mars is committed for almost two years. In normal ...


18

By the time Starship launches for Mars, SpaceX may have changed the number of legs several times. They redesign as quickly as the Haggunenons of Vicissitus Three evolve during lunchtime. Plausible guesses for factors favoring three legs, at the moment: lighter less aerodynamic drag, if the legs also act as fins send a scout beforehand to choose a boulder-...


17

They are COPV (Carbon Overwrap Pressure Vessels). They are high pressure gas tanks. Basically a steel tank with carbon fiber on top to make them stronger so they can hold very high pressure gasses. People have gotten close up 'spy photos' of the label which suggests the latest ones (used on SN3) say CNG only (Compressed Natural Gas, aka Methane, aka CH4). ...


12

Quick answer is all I have time for now -- if someone wants to do a more detailed and referenced answer, please feel free and I'll delete this: While it's very big, its mass is not that high, and gravity is low. On Mars, for instance, it needs about 150 tons of fuel, plus 100 or so tons of vehicle (mass) to get back to orbit. Under Mars gravity thats only ...


11

SpaceX has implied that there will be a crew/cargo lift system similar to how skyscraper window washing platforms work (a crane swings the platform out from inside and lowers it to the ground): SpaceX teased it at the end of this video from last year:


10

This has been answered before, but I chose not to just mark it a duplicate because there is one new reason for the header tank unique to Starship. In a Reddit AMA in 2017 where Elon Musk answered questions about the original ITS design, he answered a question about the header tanks: Those are the header tanks that contain the landing propellant. They are ...


9

There was some talk of modifying Falcon 9's second stage to give it full reusability in November of 2018. The idea was that a reusable second stage would be used to test out Starship technologies. This effort was scrapped 10 days later in favor of accelerating development on the current stainless steel design of starship. The superheavy/starship ...


9

Two things-- You are comparing an (estimated) cost (Starship Launch) with a price (reusable Falcon 9 launch). The actual cost of a reusable Falcon 9 launch is less than what they will charge for it-- the actual cost is known only to SpaceX, but external estimates run as low as $20 million. The cost of the Starship launch is optimistically estimated at ...


8

An answer might be, that three legs will always be able to land on a rough surface with all three legs touching the ground, while with four legs there is the possibility that only three of them will touch the ground. In order for the four legs version to touch the ground with all four legs, those legs should be made telescopic with some sort of dampers, ...


8

You can find most of the information you need on the picture below which comes from Reddit. Crucially, if you add up the relevant lines, delta-V from Mars to Earth-Mars transfer is about 5.92 km/s. Assuming they produce the vacuum raptor (not planned for the very first starship missions) Starship will have an $I_{sp}$ around 380s, so by the rocket equation,...


8

Ultimately the pump, whether electric or combustion-turbine driven, needs a certain amount of total energy input to do its job. Combustion reactions both deliver more total energy per mass than batteries, and deliver it faster. From an article on gas versus electric cars: Stored energy in fuel is considerable: gasoline is the champion at 47.5 MJ/kg and ...


7

As per March 2020 with the release of the Starship users guide more details emerged: "To deploy the payload, the clamshell fairing door is opened, and the payload adapter and payload are tilted at an angle in preparation for separation. The payload is then separated using the mission-unique payload adapter. If there are multiple payloads on a single mission,...


7

The amount of energy involved in a take off and landing will be roughly equal to the mass being moved, and approximately the same proportion of energy will be turned into sound given the same engines are involved. Going up a falcon heavy is around 1400 tonnes, coming down the stages have split apart and are almost empty. Have not found authoritative numbers ...


7

No, not from Earth. According to Elon Musk's most recent comments at SpaceX's 2019 Starship Update presentation, Starship cannot reach orbit without the Super Heavy first stage booster, at least on Earth. (Though when launching from the moon or Mars it's no problem.) Previously in 2018 Musk had stated on Twitter that Starship would be technically capable ...


7

Similar to how a small plane can't really carry any people around the world, but a larger plane can, it turns out there are challenges to making really small rockets. These are magnified when you take in to account full reusability. It turns out that Starship is about the smallest spacecraft that makes sense for a fully reusable spacecraft. A few things to ...


7

The most sensible and specific account I've come across is as follows: RUPTURE UPDATE: Through back channels it has been revealed that MK1 suffered an accidental overpressure to failure. Fuel and oxidizer would typically be loaded to 3 Bar or 43.5 psi— for densification purposes and flightworthy tanks may be tested to 1.5-2x that value for single time ...


7

Well, an approach to this is to try and calculate how much power might be needed, and you can make a hack at this. Since I don't know how large the flaps are or various other critical parameters (and I am not sure this information is public) I can't actually calculate what the real power requirements are: rather this answer gives you the expression you need ...


6

There are 3 possibilities: SpaceX deliberately rolled it It rolled naturally, and SpaceX did not expect / want this It rolled naturally, and SpaceX did expect / want this. Looking at the video, the roll seems to intensify without any use of the rcs thrusters, so it seems likely the roll occured naturally. In this case, the torque that induced the roll ...


6

As @camille-goudeseune writes, we shouldn't draw any conclusions from this "flying water tower" towards the design of the final Starship which will be an order of magnitude larger. Nevertheless, we can have a look why it makes sense to have three legs on Starhopper: It's true that the three legs need to extend 1.4x from the center of the body of the ...


6

To those who want more specificity. Pictures are borrowed from post from geoffc. Elon Musk: There’s a puck at the base that takes the engine thrust load. In the photo below the three engines are mounted at the green circles. The thrust puck distributes the thrust from the engines to the larger structure. The entire structure circled in red is the "...


6

The relevant quantity here is delta-V. Starship, when fueled in orbit will have about 6500 m/s of Delta-V budget available with 100 tons of cargo. It takes pretty much that whole budget to land the cargo on the moon (about 5500). Unloaded, it's weight is reduced by a third, which isn't a whole lot, so the remaining fuel is nowhere near enough to bring ...


5

I think it’s because they want to use the same pipe work they use for tanking on the ground in orbit. I imagine the Starship will have an LOX inlet/outlet on one side and a Methane inlet/outlet on the other and all Starship will be built in the same way. If you back one Starship onto another with the heatshields pointing in the same direction the LOX pipe ...


5

Yes, SpaceX continues to build Falcon 9 first stages. COO Gwynne Shotwell said in an interview in Spaceflight Now's SpaceX poised to accelerate launch cadence with series of Starlink missions that she expects SpaceX to produce 10 Falcon 9 first stages in 2020. This is down from about 16-18 per year that they had been building. Engineers and staff that used ...


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