Re: [Starlink] orbital maneuvers 12 per sat in the last 6 months

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

[-- Attachment #1: Type: text/plain, Size: 5213 bytes --]

Now there is the misuse of the expression "exponentially" in cases when people just mean "a bit faster than before". If you have a time series 1, 2, 4, 6, 8 then you could claim that it's exponential because the first three terms double each time, yet the last four terms could be used to claim that it's linear.

Plus, exponential growth doesn't necessarily mean fast growth. Your 2020 term deposit for 5 years at 1% interest rate with interest reinvested sees your money growing exponentially, too. This is perhaps why decision-makers from the economics sphere tend to get caught out be fast exponential growth (the sort of growth us science and engineering folk tend to think of).

Beyond that: I'm not sure that I can make much of orbital maneuver numbers. Even GEO sats - for which collision probability is very low - undertake regular corrective maneuvers for station-keeping. For anything further down, a maneuver could be a short-term evasive action, a longer term orbit injection or change maneuver, or corrective action to any of these.

Each maneuver uses some of the satellite's propellant reserve. As a general rule, a maneuver executed over a longer period of time is more fuel efficient: A small change in a satellite's trajectory now can lead to a large change down the time axis, with very little propellant use - think Starlink satellites transitioning from launch train to final station over months. Making small corrective adjustments to this over time might bring the total number of maneuvers up, too. Conversely, large short-term corrections dip into fuel reserves, which can impact on service life. So you'd really need to ask which sort of maneuvers these are, and how much each maneuver costs in terms of service life.

--
****************************************************************
Dr. Ulrich Speidel

Department of Computer Science

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

The University of Auckland
u.speidel@auckland.ac.nz<mailto:u.speidel@auckland.ac.nz>
http://www.cs.auckland.ac.nz/~ulrich/<http://www.cs.auckland.ac.nz/%7Eulrich/>
****************************************************************
________________________________
From: Starlink <starlink-bounces@lists.bufferbloat.net> on behalf of David Lang via Starlink <starlink@lists.bufferbloat.net>
Sent: Friday, July 7, 2023 6:02 PM
To: blakangel@gmail.com <blakangel@gmail.com>
Cc: starlink@lists.bufferbloat.net <starlink@lists.bufferbloat.net>; Daniel AJ Sokolov <daniel@falco.ca>
Subject: Re: [Starlink] orbital maneuvers 12 per sat in the last 6 months

they have been filling shells (altitude sets), so it makes sense for the numbers
to have been going up.

we'll have to see if they keep going up as much as they move on to different
altitude shells.

David Lang

On Thu, 6 Jul 2023, blakangel@gmail.com wrote:

> I think the main point of the article is that the amount of maneuvers needed
> is currently increasing exponentially: "It's been doubling every six months,
> and the problem with exponential trends is that they get to very large
> numbers very quickly." I'm wondering if they are not taking into account the
> massive amount of satellites that have been launched since the previous six
> month report.
>
> I found the semi-annual reports filed w/ the fcc:
> https://licensing.fcc.gov/myibfs/download.do?attachment_key=23204343<https://licensing.fcc.gov/myibfs/download.do?attachment_key=23204343> and
> https://licensing.fcc.gov/myibfs/download.do?attachment_key=23204338<https://licensing.fcc.gov/myibfs/download.do?attachment_key=23204338> for gen
> 1 and gen 2 constellations.
>
> Still reading them and haven't found the older ones yet to compare.
>
>
> David Lang via Starlink wrote on 7/6/2023 9:49 PM:
>
>> some people are assuming that more satellites launched will mean more
>> maneuvers needed (not recognizing that what matters is only the things at
>> the same altitude)
>>
>> plus, it's a scary large number :-)
>>
>> David Lang
>>
>>  On Thu, 6 Jul 2023, Daniel AJ Sokolov via Starlink wrote:
>>
>>> On 7/6/23 17:54, Dave Taht via Starlink wrote:
>>>>
>>> https://www.space.com/starlink-satellite-conjunction-increase-threatens-space-sustainability<https://www.space.com/starlink-satellite-conjunction-increase-threatens-space-sustainability>
>>>>
>>>> I am under the impression that each sat is capable of about 500 over
>>>> the satellite's lifetime. I am curious as to what they are avoiding.
>>>
>>> Assuming your number of 500 is correct, I don't see any worry here. 12
>>> moves in 6 months makes 492 in 20.5 years. That is less than 500 and
>>> beyond the lifetime expectation of the satellite anyway.
>>>
>>> A I missing something?
>>> Daniel AJ
>>> _______________________________________________
>>> Starlink mailing list
>>> Starlink@lists.bufferbloat.net
>>> https://lists.bufferbloat.net/listinfo/starlink<https://lists.bufferbloat.net/listinfo/starlink>
>>>
>> _______________________________________________
>> Starlink mailing list
>> Starlink@lists.bufferbloat.net
>> https://lists.bufferbloat.net/listinfo/starlink<https://lists.bufferbloat.net/listinfo/starlink>
>
>

[-- Attachment #2: Type: text/html, Size: 8167 bytes --]