[Starlink] Re: Starlink and Iran

Ulrich Speidel
2026-01-16T23:30:15Z

On 17/01/2026 8:03 am, Michael Richardson wrote:
> Ulrich Speidel via Starlink <starlink@lists.bufferbloat.net> wrote:
> > here. Why? Because there is a limit on the amount of power per square metre
> > and MHz of bandwidth (EPFD) that systems such as Starlink may project onto
> > the surface of the Earth. It's an ITU-imposed limit, so the FCC can't really
> > do much about it. SpaceX are on public record for not being happy with it and
> > with their v2's they're riding right up against that limit.
>
> 1. Who checks/enforces this ITU limit?
The licensing authorities in the respective countries (i.e., the FCC in
the US - and they're held to account by their competitors, of which
SpaceX has a few in the US). At an international level, if one country
were to ignore this, so would everyone else, which would make
space-to-ground comms in these bands pretty unworkable pretty quickly as
there'd be a lot of "my output power is bigger than yours" happening.
One of the main reasons for having this limit is to ensure GEO sats can
get their signals through. Whether the current level that the limit is
set at and the way it's computed is appropriate is another question, and
SpaceX have certainly tried to litigate that before the FCC.
> 2. Could the physically satellites go higher over some territory? How much higher?
> I assume it's software controlled.
A satellite has three types of energy that determine its orbital motion:
Potential energy from orbital height, kinetic energy from moving, and
energy stored in its thruster fuel. If you don't use the thrusters, the
normal course of events is that over time, you convert potential energy
into kinetic energy and eventually lose height to end up in the upper
reaches of the atmosphere where you burn up. To increase or even just
maintain orbital height, you need to convert fuel energy and kinetic
energy into potential energy. Just converting kinetic energy into
potential energy isn't enough - it leaves your satellite with too little
kinetic energy to keep orbiting. So yes the satellites can in principle
go a bit higher but at the expense of fuel and therefore lifespan.

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Dr. Ulrich Speidel

School of Computer Science

Room 303S.594 (City Campus)

The University of Auckland
u.speidel@auckland.ac.nz
http://www.cs.auckland.ac.nz/~ulrich/
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