SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake • Hacker News Board

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#101

Post by JumpCrisscross » Fri, Jan 23, 2026, 9:29 PM UTC

ben_w wrote: post #98

JumpCrisscross wrote: post #90

Earlier quoted context omitted.

> there is a pretty good chance Source?

You're quoting something I didn't write; but to the point that we may already be in the early stages of a cascade, here's the modelling behind it: https://conference.sdo.esoc.esa.int/proceedings/sdc9/paper/3...

This paper is brought up elsewhere in this thread and responded to. TL; DR It raises interesting modelling strategies, and develops on cool numerical methods from Kessler (2001), but it's far off from "pretty good chance."

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#102

Post by estimator7292 » Fri, Jan 23, 2026, 10:10 PM UTC

kbelder wrote: post #100

direwolf20 wrote: post #94

Earlier quoted context omitted.

Is it still a small number when multiplied by the square of the number of satellites and the number of times they orbit each day?

Don't know. But I'm sure that people at NASA and other such places have done that calculation. I just wanted to point out that orbital space is big, so you have to do the math to see if there's an actual problem.

They have, and it is. It's a big problem.

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#103

Post by aucisson_masque » Sat, Jan 24, 2026, 10:56 PM UTC

NetMageSCW wrote: post #69

aucisson_masque wrote: post #9

Earlier quoted context omitted.

You don’t need 10k missiles. You need just one to blow up all of starlink satellites. This is like bowling, you hit one, it hits the other one etcétéras.

That is not how it works at all. Imagine using a rocket and blowing up one car on a highway - how many other cars will actually be affected? How many cars on other highways will be affected?

https://en.wikipedia.org/wiki/Kessler_syndrome

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#104

Post by goku12 » Sun, Jan 25, 2026, 6:55 PM UTC

x______________ wrote: post #85

goku12 wrote: post #58

Earlier quoted context omitted.

Let me see if I can. Before we go to space, let's try something on the ground. Imagine pitching a ball horizontally. What do you expect if you pitch it too slow? The ball will curve more towards the ground and meet it early, won't it? (In other words, it doesn't go very far and doesn't stay airborne for long). Going from ground to space, this action remains the same. You need to 'lower an orbit'? Reduce its forward v…

>[10].. From the looks of it, you still are teaching. Very informative read! Extra points for non-referenced footnotes! =)

Thank you for your kind words! Glad you liked it! It's during instances like this that I wish I really wrote things down and preserved them.

Re: SpaceX lowering orbits of 4,400 Starlink satellites for safety's sake

#105

Post by goku12 » Mon, Jan 26, 2026, 12:02 PM UTC

wolvoleo wrote: post #96

laughing_man wrote: post #78

Earlier quoted context omitted.

Satellites need thrusters for station keeping. Otherwise they drift out of their desired orbits over time.

Yes though the smallest ones like cubesats don't have them. They do tend to have rotation wheels for keeping themselves aligned but they can't actually affect their own orbit.

You're correct. I'm just going to add a bit more technical context here. The process of keeping a steady orbit is called 'station keeping'. Similarly, the process of maintaining the correct orientation/alignment is called 'attitude control' (attitude is the technical term for orientation).

Attitude control can be achieved to a finite limit using momentum wheels or reaction wheels. But at some point, it will reach its maximum speed and its control capability saturates. You will need to 'desaturate' the wheels and restore its control capability. One method is to produce a counter torque using special reaction control thrusters (RCT) called 'attitude control thrusters'. That needs propellants. Smaller satellites don't have that luxury. So they exploit Earth's magnetic field by using a 'magnetic torquer' to produce the counter torque against it. That needs only power, not propellants.