No launch clamps and no launch pad on the moon or Mars, then how the starship is going to take off, forget the perils of landing, at the first place? If it is a one way trip, why fuel tanks for the return trip ?


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Starship will take off the same way that it lands using rocket motors that are located higher up on the ship and angled out slightly thus avoiding the problems of the impingement of the rocket plume on the surface directly below the landing legs. The exact details have not been worked out yet but in principle it will work as shown in this video:

  • $\begingroup$ I doubt. It takes 3 raptor engines to take off this monster from the Earth. The header tank is only for reentry. $\endgroup$
    – seccpur
    Commented Oct 31, 2020 at 13:20
  • $\begingroup$ @seccpur 3 Raptors are slightly over half the thrust needed to lift off while fully loaded and fueled, in a gravity field six times as strong. You only need about half of what a single Raptor can produce at minimum throttle to take off from the moon. And since the HLS Starship won't ever reenter atmosphere and land on Earth, the header tanks may be repurposed (modified if necessary) for lunar launch propellant. $\endgroup$ Commented Oct 31, 2020 at 16:06
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    $\begingroup$ @seccpur Well I'm no expert. I suggest you argue the point with SpaceX a picture of this arrangement is on their website under the section on returning people to the Moon: spacex.com/human-spaceflight/moon/index.html. Note these engines might use high pressure gaseous propellants as they will not need to fire for long. And the force required to lift 1200 tonnes off of the Earth is hardly comparable with the force required to lift a few hundred tonnes off of the Moon. One vacuum raptor would be fine once the ship is a few dozen metres up. $\endgroup$
    – Slarty
    Commented Oct 31, 2020 at 16:40

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