Re: [Starlink] Starship's 4th flight test was magnificent

[Ulrich Speidel <u.speidel@auckland.ac.nz>]

On 11/06/2024 12:04 am, David Lang wrote:
> As I understand it, Starlink does not have ground stations transmit 
> towards the geostationary satellites, they only target the starlinks 
> when they are not in line to avoid exactly this problem)
Correct.
>
>> Conventionally, if you had to communicate your re-entry video or 
>> audio feed to a ground station, you had to communicate *through* that 
>> cone's wall. Similarly, if you wanted to go "up", you had to go to a 
>> TDRSS satellite, of which there were only a small number in orbit - 
>> and the one visible to you would have been on the other side of the 
>> plasma cone wall with high probability. With Starlink, you have 
>> potentially a few dozen satellites within field of view, and the 
>> chances of having one within view out the back of the cone are 
>> relatively good (but not guaranteed). The other day, they got lucky 
>> that the star(link)s lined up ;-)
>
> As I underand it, it's not just luck, the Starship is so much larger 
> than anything else that the plasma does not just wrap around the craft 
> and close up behind it, the sheer size of the craft gives the plasma a 
> chance to cool a bit (and you can see that in the videos)
That'll probably help, yes.
>
> Also, if it was 'luck' then they were lucky on both Starship reentry 
> flights (and since the ship was tumbling during flight 3, that would 
> be saying a lot)

I guess the problem is hard to quantify - essentially you have to have a 
Starlink satellite that's within the steering cone of one of the phased 
arrays on Starship AND the path to which doesn't lead through a cone 
wall AND that's been assigned to serve that particular phased array AND 
that needs to work out through handovers to other satellites for your 
entire flight. That's probably possible a large percentage of the time 
given the number of sats about now, but perhaps not 100% (yet), 
especially around tropical latitudes where satellite density is about 
half of what you get in the 30's to mid-50's. And yes I guess they were 
probably lucky in that sense, yes.


-- 
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Dr. Ulrich Speidel

School of Computer Science

Room 303S.594 (City Campus)
Ph: (+64-9)-373-7599 ext. 85282

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ulrich@cs.auckland.ac.nz
http://www.cs.auckland.ac.nz/~ulrich/
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