SpaceX


#141

Starlink is SpaceX’s plan for satellite internet. To reduce latency that we see today they plan to use a series of low and very low-level ‘meshes’ that use lasers to communicate with each other.

Potentially it means very fast internet everywhere, which is essentially a license to print money. It even has the capability of being faster than existing ground fiber optics. By using SpaceX reusable launchers the economics of 1000 small satellites becomes possible.

Prof. Mark Handley of UCL did a video of how it could work (with weird computer voice, but whatever), with paper here. Interesting stuff indeed:

A log cabin and fast internet. Cool. :wink:


#142

I like it, but hopefully those geniuses are also thinking about this problem -


#143

“Space is big. Really big. You just won’t believe how vastly hugely mindbogglingly big it is. I mean you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.”

I agree there should be a plan to de-orbit, but these things are small and space even in orbit is big, especially when the location of all of them is known.

Another way to put it is that there are 66,500 7-11 convenience stores world-wide, which is a lesser number than the maximum satellites in a mesh needed for all time. A single 7-11 store could also contain in area size all of the satellites as well. Now I drive pretty fast and have never crashed into a 7-11, and sometimes can drive days without it even being close. :slight_smile:


#144

So my non technical rebuttal to this would be thus:

Space anywhere is big until you start filling it. Now that is a specious argument by me but I think you see what I am getting at. All you are saying is that the problem is a long way off. The planet is literally getting hotter because of a similar viewpoint.

As for the 7-11’s analogy - its cute, but we have a plan for what to do when a 7-11’s slurpies no longer bring joy to those in its proximity. That plan looks like a bulldozer. All I am saying is that they should be thinking about what to do with stuff in low orbit when it has outlived its usefulness before putting it there. Not an argument between us as we both agree they should be working on it.


#145

So… Like… This?


#146

I have long held that there are other species out there, that in fact that there are many of them out there, that they have been here, and that they, as a group, have put “do not enter” beacons around our solar system. I can’t help but think that intelligent species would see us at first glance for the locusts that we are.

So yes - just like that!

Maybe Spacex invents a powerful laser to remove them like hair removal.


#147

I agree, always have a plan/insurance/money to de-orbit but the ‘we will bump into them a lot’ is the counter-intuitive bit. It helps because they are so small and so low (because they are so small) compared to existing satellite tech. It also helps that it will take propellant/action to actually keep them in a stable orbit (atmospheric drag), so a bankrupt Starlink one day means a light show and no-more mesh.

For 7-11 analogy it was just more a sense of scale, as in animations and stuff can be deceptive, in if you look up then there are less planes, so the representation is often off.

Being able to get fast internet via a pizza boxed size phased antenna rather than a land line pretty much anywhere in the world might have a (good?) impact on society as well. I find it exciting.


#148

Have you read ‘The Three-Body Problem’? It’s a bit schlocky but a good read.

It introduces ‘The Dark Forest’ theory on why we should not be emitting lots of RF junk like we do. There’s a reason it is so quiet out there…


#149

I tried to do that to a US gov’t office once, they didn’t like it.


#150

The other problem with the 7-11 analogy is:
In your car you can change your course at will and you can accelerate and decelerate, even to a standstill.
Most objects in orbit can’t.

Destroying them doesn’t make things better either, in fact in makes the problem far worse.
If you blow up an old satellite you create a few hundred new objects that are fast enough to punch holes into everything. They are also too small to track all of them effectively. So you are better off keeping one satellite and tracking it.


#151

That’s right. “Ablation cascade” is a fancy word but quite descriptive! :slightly_smiling_face:

There have been a few anti satellite missile tests by US and China and each time there has been a fair amount of political aftermath because of the debris caused.

As stated I think the key is the low low orbits of the satellites here so they deorbit and burn off safely rather than staying up cluttering the skies.


#152

Yeah pretty much every orbit below…400km or so will degrade fast enough so those satellites don’t stay up there forever.

Those over 1000km are pretty much forever.

Also interesting in that regard: the ESA already tested an ion drive that could enable satellites to maintain very low orbits (they talk about lower than 200km) for years.
That sounds very intriguing to me because such satellites would deorbit within days after their end of life. Satellites in such low orbits are also useful for various purposes (just because they are close).


#153

That is cool - on the other hand such an ion drive would probably have enough delta-v for a deorbit burn from a higher orbit too so it would sort out a lot of issues really.

Probably mostly useful for small satellites because of the small thrust amount but that’s the direction things are going anyway :slightly_smiling_face:


#154

Indeed.
But the main perk is actually that you don’t have to actively deorbit them. If everything bad happens you have a few hours to fix it, and if you can’t then the satellite will be gone, but there will be no debris.
If you lose control of a 1000km satellite and for some reason it cannot make the reentry burn automatically, then it becomes a monument of human failure that stays up there forever.

And yeah Ion drives are a magical thing. Such high Isp in those! (although very low thrust. Thrust values of the ion engines in KSP are wet dreams of real life engineers)

Combined with the fact that reaching such low orbits with small satellites is very easy (small rockets make it comparatively cheap) that really makes it intriguing. For some purposes anyway.


#155

Good point re the low orbit!

One of my favourite clumsy creations in KSP was a butt-ugly straight-wing cargo biplane that was capable of a roughly suborbital hops with maybe a minute or two over the Kerbal ‘space’ line - I hauled heaps of minisatellites and ion tugs etc. to orbit with it: release the payload at 70km altitude, then hop into that satellite and do a little burn to get periapsis above 70km, then hop back to the cargo plane quickly to do a shuttle style gliding return to the spaceport :slightly_smiling_face: No degrading orbits in stock KSP though hehe…


#156

I love that mission profile!
I did a lot of such missions. My spaceplane roughly looked like the Skylon.

…man I have to play KSP again…


#157

Zee capsule vil go up like a cannonball…zen zee capsule will come down like…uh…cannonball… Parachutes will open to spare the life of zee specimen inside.

Specimen?

Space-e-man…!

LOL…one of my favorite interactions in that movie…


#158

The other problem with that analogy is when a 7-11 is abandoned it will sit right where it was. You’ve never seen one drifting across a road because there was no one left to make sure it sat still.


#159

Launch in about 10 mins:

https://www.spacex.com/webcast

“Falcon 9’s first stage for the Es’hail-2 mission previously supported the Telstar 19 VANTAGE mission in July 2018. Following stage separation, SpaceX will attempt to land Falcon 9’s first stage on the “Of Course I Still Love You” droneship, which will be stationed in the Atlantic Ocean”


#160

Perfect landing.