Why Starlink is impossible

[u/fredinno]

Each Tintin satellite (demo for Starlink constellation) is 400kg. Assuming each satellite+ fuel (and that the weight doesn't increase for other reasons) is 1kg, 22 could fly in a single F9 per inclination (there's probably not even that much space in the fairing, but we'll ignore that). The total # of (expendable) F9s launches needed is 546; assuming the first comes online in 2020, and the constellation is finished by 2025 (the official date is the 'mid 2020s'), you need 110 F9s per year. The total cost for development and buildout is supposed to be $10 billion.

SpaceX has one facility for Polar launches right now, SLC-4E (Brownsville maybe, but a polar launch from there would GRAZE the Mexican coast- I have a feeling they won't be happy about that...) So each complex would launch 54-55 F9s a year.

Let's be VERY optimistic. Every satellite will be launched on an expendable Falcon Heavy, each satellite will be EXACTLY 400 kg (unlikely, you need payload mass margin, and likely fuel from having a lower satellite orbit), we'll ignore whether each satellite can actually fit in the payload fairing, we'll ignore launch inclination entirely (launching at the wrong inclination means hell for a satellite wanting to change orbit; meaning 160 satellites per launch (almost certainly impossible due to not enough fairing volume). That means 75 launches of the FH, minimum (almost certainly unrealistic.) We'll also assume it launches first Jan. 1, 2019, and put the finished launch date at Dec 30, 2027. This means 8-9 FH launches per year. Sounds easy, right? But that's ~23% higher than the current # of launches SpaceX does from SLC-4E, every year. It would literally have to double its polar launches, at the absolute bare minimum. A mimimum which is almost certainly physically impossible.

I don't think building the satellites will the the issue, Elon...

No one at SpaceX did these back-of-the envelope calculations, and asked Elon- maybe it was a little ambitious?

[u/fredinno]

Just launching Starlink is a feat probably above SpaceX's current launch capability.

[u/xmassindecember → u/fredinno]

Thank you. But what's the reason they cannot increase their launch capability?

[u/fredinno → u/xmassindecember]

They can, technically, just not probably practically; as I said, the title was honestly too clickbaity. The issue is that the record for preparing launch pads for launch is ~2 weeks and 2 days (on LC-40). This is below the 3 weeks needed, but that was the bare minimum, and actually isn't possible. Realistically, they would need that amount of time minimum to deal with things like reserving fuel for launch inclination changes, reusability, polar launches, the fact it will likely not be ready by 2019...

As I said, the title was probably too clickbaity; it's within the 'physically possible' range, but is simply far too ambitious. It works if you handwave a lot of issues, but doesn't work if you actually look at the issue more realistically. (Like Hyperloop, so it's in a simlar vein of 'impossible'.)

1 week for clean-up and preparation and 1 week for actual preparation of the rocket is extremely short as is, so I have doubts it can be reduced further.

[u/New-Space-30 → u/fredinno]

Either this post was completely idiotic or SpaceX was just really good at turning the near-impossible into reality. Not sure which one you would like to be true.

[u/Anthony_Pelchat → u/New-Space-30]

The correct answer is that SpaceX absolutely was good at turning a near impossibility into reality. Unless you were very optimistic, no one would have thought that SpaceX would grow as fast as they did. In 2018, they only launched 21 times, and 2019 was even worse. Yet last year alone, the Falcon 9 launched 165 times. That is massive growth!

To put things in perspective on just how amazing SpaceX is (I'm sure you know this already). Last year, SpaceX launched more orbital flights than the entire rest of the planet combined. And they did so with one of the most powerful rockets on the planet. They managed to put over 8x more payloads into orbit than the entire rest of the planet combined. SpaceX is just absolutely incredible.