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posted by martyb on Monday September 30 2019, @12:00PM   Printer-friendly
from the about-twice-the-thrust-of-a-Saturn-V dept.

SpaceX's "completed" Starship Mark 1 (Mk1) prototype was unveiled during an update presentation in Boca Chica, Texas on Saturday. The craft has two less-prominent aft fins instead of the three larger fins (acting as landing legs) seen in previous renderings, and two small fins on the nosecone. An upcoming 20 kilometer test flight of Mk1 will only use three sea level optimized Raptor engines, while the full version of Starship will use three sea level and three vacuum optimized Raptor engines. The dry mass of Starship will be higher than initially expected: about 100-120 tons instead of 85 tons (Mk1 is 200 tons). Payload to low Earth orbit (LEO) in fully reusable mode will start out near 100 tons but is expected to reach 150 tons.

SpaceX is currently making one new Raptor engine every 8-10 days, but hopes to speed that up to one engine every day in Q1 2020. The process of building Starships will also speed up due to unspooling steel and using single seam welds (giant rings of steel will still be joined together, but without the plates seen in Mk1). A Starship Mk3 could be completed within 3 months, and a Starship Mk3, Mk4, or Mk5 (with the Super Heavy booster) could reach orbit within 6 months from today. It may not be possible to get a Starship to orbit by itself, but even if it could, it would be expendable and not worth it. Therefore, orbital tests will depend on the rate of Raptor engine production. Around 100 engines will need to have been made by the time of the first test. Super Heavy could use as few as 24 engines to complete a mission, but is more likely to use 31, or a maximum of 37 engines. The amount is configurable as needed.

Elon Musk claimed that SpaceX could launch people on a Starship as early as next year, and that in-orbit refueling (called "orbital refilling" during the presentation) of Starship will be easier than docking with the International Space Station. The refueling process is necessary to get the full 100-150 tons of payload to the surface of the Moon, Mars, or other solar system destinations.

Musk estimated that a small fleet of 10-20 Starships could launch about 1,000 to 10,000 times as much mass to orbit in a year than is currently launched with all of the world's rockets annually, including SpaceX's Falcon 9/Heavy.

Also at NASASpaceFlight, Ars Technica,, and CBS.

See also: r/SpaceX Starship Presentation Official Discussion & Updates Thread
SpaceX debuts Starship's new Super Heavy booster design
SpaceX envisions Starship-enabled cities on the Moon and Mars in new renders
Tesla on Mars addressed by Elon Musk in SpaceX's Starship Q&A session

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  • (Score: 2) by Absolutely.Geek on Sunday October 06 2019, @07:29PM (1 child)

    by Absolutely.Geek (5328) on Sunday October 06 2019, @07:29PM (#903470)

    Agreed; a space elevator could work on The Moon; and I have always been partial to the idea.

    But a train is in my opinion; significantly easier to construct. Power from a few square kilometers of panels at the poles that are always illuminated.

    The train idea came from looking at the orbital ring idea; []; and modifying it for the moon, it could be used for transport to different places on the moon also.

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  • (Score: 2) by Immerman on Sunday October 06 2019, @11:15PM

    by Immerman (3985) on Sunday October 06 2019, @11:15PM (#903510)

    Is it really though? To construct a train useful for orbital launch you have to create a pretty frigging straight railway - which means carving tunnels and valleys, and building bridges, across ~11,000km of radiation-blasted hard vacuum to build something far straighter than any railway on Earth, across far more dramatic landscape. And then you have to build far the longest maglev track ever built, under those same harsh conditions.

    Compare to a beanstalk, where you have to ship cable segments to the current ends of cable extending in both directions from L1, and bolt them on. Along with providing a bit of propulsion at L1 to keep the center of mass from drifting too far toward either planet(oid) - or alternately, just deploying the new cable tip sections in a controlled fashion, extending deeper into one gravity well or the other to pull the center of mass back into alignment.

    Now, an orbital ring idea has potential, except that simple lunar orbits tend to be quite unstable, though perhaps the ring itself could be harnessed in some self-stabilizing manner, where an isolated satellite could not. (My personal favorite is a skyhook with a multi-km crane on the end - capable of hooking stationary payload directly from the moon's surface, and lobbing it, at the extreme, beyond the orbits of either Mars or Venus.. Sadly the stabilization issue strikes that one hard, but there might be a low-propellant solution if someone looks hard enough)

    Of course, I suddenly realize that there's no particular reason you'd need a moon-circling railway for launch. With 1G of acceleration, and a 2.4km/s escape velocity on the moon, you need a track length of only
    s = 1/2*v^2/a... or (2400m/s)^2/9.8m/s^2 = 294km. That's a lot easier to provide than 11,000km, and we could probably find lots of relatively flat areas to install such a railway without requiring huge earthwork projects. We could do even better though, if higher acceleration is acceptable. At 2G we need only 143 km of straight rail, at 10G, 30km.

    At the other end of the power spectrum, allowing for vastly weaker maglev systems, we could build maglev launch rings, but you really need to be able to handle extremely high centripetal accelerations for those to make sense: 1G of centripetal acceleration requires a radius of r=v^2/a = 587km . But if you could handle 100G (such as inert payload) you could get away with as little as 37km of track in a 12km ring, and the track need only provide very gradual linear acceleration. And if you added a 6km tether to provide the bulk of the centripetal force, the maglev track need supply only very small stabilizing support forces as well - allowing for the possibility of (relatively) cheap, compact bulk launch facilities. Provided your launch pods could survive the stress of course. And of course, a round track is a lot less forgiving for landings - and if you can do landings then you can potentially recapture much of the launch energy during deceleration, needing only provide energy generation for whatever net mass-flow there is away from the moon.