From: alain245@videotron.ca   
      
   On 2024-03-14 4:31 p.m., Niklas Holsti wrote:   
   > On 2024-03-14 20:49, Alain Fournier wrote:   
   >> On 2024-03-14 1:59 p.m., Niklas Holsti wrote:   
   >>> On 2024-03-14 18:52, Alain Fournier wrote:   
   >>>> On 2024-03-14 10:53 a.m., The Running Man wrote:   
   >>>>   
   >>>>> NASA won't be too happy with this since it will make a 2025 Lunar   
   >>>>> landing all but impossible. Even 2026 is dubious.   
   >>>>   
   >>>> I wouldn't say that. Reusing the stages isn't required to reach the   
   >>>> moon. That only allows SpaceX to make big profits. It seems to me   
   >>>> that the booster showed today that it can put the ship were it needs   
   >>>> to be to reach orbit. The ship did not reach orbit simply because it   
   >>>> wasn't trying to reach orbit. The ship didn't succeed in its reentry,   
   >>>> but there is no reentry involved in the moon mission.   
   >>>   
   >>>   
   >>> If the tanker ships, for refuelling the Lunar Starship in Earth orbit,   
   >>> can't reenter and be reused, it will be /quite/ expensive, right?   
   >>>   
   >>> There have been various statements about the number of tanker launches   
   >>> needed for one lunar mission, but there seems to be agreement that the   
   >>> number is about 10 or more.   
   >>   
   >> Yes it would be quite expensive. But I think they will view that as   
   >> development cost until the do achieve intact return.   
   >   
   >   
   > You may well be right. If they can get the boosters to return and be   
   > reused, the cost of single-use tankers may be bearable for a while.   
   >   
   > However, while SpaceX said that this flight tested the opening and   
   > closing of the payload door, and the in-orbit propellant transfer, they   
   > have not yet said whether those tests were successful.   
   >   
   > For the payload door, after the SpaceX commentators said the door was   
   > closing, some of the video from inside the payload bay seemed to show   
   > the door swinging loose and bending back and forth at the same time as a   
   > disting "clunk" sound was heard; that did not seem successful to me.   
   >   
   > SpaceX admitted that the ship roll rate prevented the re-ignition test   
   > of a Raptor engine; apparently the roll rate was uncontrolled and too   
   > high. This may have messed up the propellant transfer test, and   
   > certainly the ship's uncontrolled attitude seemed to be one factor that   
   > doomed the re-entry. At some points in the re-entry the ship had the lee   
   > side towards Earth, certainly not planned.   
   >   
   > If the payload door was not well closed for re-entry, that may have   
   > contributed to the ship's re-entry failure.   
      
   Actually, I think I prefer attitude control problems. If the destruction   
   of the ship was due to insufficient thermal protection or something like   
   that, it could signal a hard to solve problem. But I think that we will   
   all agree that SpaceX will be able to solve attitude control. Not that   
   it is necessarily very easy to solve, just that they did it for their   
   Falcon rocket, so there is no reason to believe they can't do it for   
   Starship.   
      
   Same goes for the booster. It hit the water hard. But we know that   
   SpaceX can get a booster to land smoothly.   
      
   Of course, it is possible that once they will have solved the ships   
   attitude control problem, we will learn that it can't actually survive   
   reentry heat.   
      
      
   Alain Fournier   
      
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