totm nov 2023 SpaceX Discussion Thread

[JoeSchmuckatelli]

50 minutes ago, SunlitZelkova said:

http://spaceflighthistory.blogspot.com/2016/12/energy-from-space-department-of.html?m=1
 

It’s actually really feasible, especially with Starship coming online. Starship is basically just a scaled down version of the Space Freighter proposed by Boeing.

Giant space death laser 

/curmudgeon

Edited November 28, 2023 by JoeSchmuckatelli
Can't read my own spelling without cheaters on this dagnabbit phone

[Pthigrivi]

Eh it sounds hokey to me. It's not a 30% difference, its 22.7%. Let's say for fun we believe Elon and Starship can deliver 150t to orbit for 1m dollars. Thats just $6.6k/t, so you could conservatively put 10kw of generation into orbit for 6k. In low orbit you're only generating half the day so that's about 43kwh/yr. That's not bad, about 4 US households worth for 6k! So you can get the power generation up there, but trying to transmit that energy over 2000km to the ground I don't think you're going to be able to beat 22.7% in losses especially considering battery, radiator, and structural mass. But that's not even the real problem. The problem is throughput. Say you were to move computation up there. Data centers currently use about 200 twh per year, about 1% of total global energy consumption. Let's say we could move 1% of that--.01% of the total--into space, or 2twh worth. Heat dissipation is a factor but its way less transmission loss because you're dumping directly into the processors. That would require 4.6 million starship launches just for the solar panels. Thats about 1% of 1% every 6,300 years. I think we can see why that's not realistic or feasible even before considering battery, processor, structural and radiator mass. 

You can try beating the energy density math by putting nuclear plants up there but the reality is rockets fail. I know no one wants to deal with this, no one wants to think about Chernobyl or Fukushima but my brothers in science those risks are real.  What does China care if industrial standards aren't up to snuff and a reactor leaks into the groundwater or melts down in Uganda?  They don't. Thats why it's cheap there, because no one actually cares what happens to anyone who lives there. But toss out the non-zero chance that a low-orbit nuclear reactor could land in the US or Europe? You might run into a few more regulatory hurdles. 

These solutions are, Im sorry to say, at best nft-esque marketing gimmicks for extracting money from unwise investors, and at worst fantasmograms designed to paint technocratic authoritarianism as salvation. It makes a lot of sense if you don’t think about it too much. Surely a society that could force a community with no democratic recourse to accept a half-baked nuclear reactor developed and build by a limited liability start-up could also force that same community to accept the consequences for their children and grandchildren if and when that ill-designed and half-maintained reactor were to fail, with zero accountability to the original investors. Real solutions tend to be much less dramatic, often utterly mundane, sadly, and don’t imagine wild-eyed investor returns. It's basic stuff like housing density and zoning reform, heat pumps, grid updates, and better transportation management. But who’s going to become a pog-faced overnight billionaire on that? Keep dumping your money into the Techy-tech scratch-off billionaire doohicky of the hour! This is a free market and you're freely encouraged to hand over everything you've made to people who know better than you do how stupid this all is.

Edited November 28, 2023 by Pthigrivi

[SunlitZelkova]

3 hours ago, JoeSchmuckatelli said:

Giant space death laser 

/curmudgeon

One of my ideas for a techno thriller set in the 2050s is to have China have a SBSP demonstrator, and when war breaks out “someone” hacks it and points it at Taipei, wreaking havoc with communications and other electronics.

IIRC the beam isn’t strong enough to hurt people usually though.

[tater]

Starlink launch in about an hour.

[tater]

 

[tater]

~4 min

 

[Elthy]

Another thing regarding space-based power would be the energy required to get something up there. I currently dont have the time to calculate it, but the thousands of tons of propellant for one launch equal a lot of energy. It will propably take a realy long time for both PV or nuclear power to just generate the energy that was used in getting them up there.

[NFUN]

1 hour ago, Elthy said:

Another thing regarding space-based power would be the energy required to get something up there. I currently dont have the time to calculate it, but the thousands of tons of propellant for one launch equal a lot of energy. It will propably take a realy long time for both PV or nuclear power to just generate the energy that was used in getting them up there.

for falcon 9, going off wiki numbers and assuming they all use max thrust (order of magnitude estimate), takes 1.6 GJ to get 22 tons. Some random site says ISS's solar panels deliver 2/3 of a kW/kg, so that's potentially 14 MW per launch. Only like a day to make up the expenditure

[tater]

There's a youtube video of a prof (Stanford?) talking about double-sided PVs that also have transmission in the layers (phased array) to function as orbital PV supply (beaming power to Earth). His case closed for high-cost power delivery to certain places like remote military bases in the arctic with 100% of the launches sourced with Atlas Vs at 2-3X the cost of a retail F9 launch.

At an order of magnitude lower cost than retail Atlas V per kg, it would be competitive with terrestrial power (assuming the PVs built at scale).

 

Caltech

 

[Exoscientist]

18 hours ago, tater said:

 

It has been assumed the booster explosion was due to fuel slosh. But it should be noted during the attempted boost back at least one engine failed to relight, and Raptors have leaked fuel and caught fire multiple times during relights in the Starship tests:

 

[tater]

Current US cost from utility companies is ~$0.10 to $0.19 per kwh. So the above is ~10X

 

 

 

28 minutes ago, Exoscientist said:

It has been assumed the booster explosion was due to fuel slosh. But it should be noted during the attempted boost back at least one engine failed to relight, and Raptors have leaked fuel and caught fire multiple times during relights in the Starship tests:

You have literally no idea why the engine did not relight. Nor do I. The people with all the telemetry data, who actually know how Raptor works? I assume they have a somewhat better idea than we have about it.

BTW, Zack Golden pointed out in his recent video that the frame of video where a flash is first seen—the bright pixels are exactly where the SH FTS is. In that case the flip caused engine outs due to starvation (see video you quoted for a possible visualization), flight path was computed to be off-nominal, FTS unzipped the vehicle.

Edited November 28, 2023 by tater

[sevenperforce]

A killer app for maximizing the utility of low-cost heavy-lift launch services can come in three flavors:

• Do it better. There are things that we do on Earth, like silicon wafer manufacturing and power generation, that are constrained by being on Earth's surface (e.g. by gravity or by lack of access to peak solar wattage) and thus could potentially be done better in space.
• Do it more. There are commodities here on Earth that don't have a large market because they simply cannot be produced at scale. An example that definitely wouldn't lend itself well to going to space is seafood farming: the price of crab (and a number of other seafood products) is high because crab can't really farmed and has to be fished. There may be commodities on Earth that have high value regardless of supply and that we've never thought of producing in space, but we could.
• Do it first. The killer app may be something we've never thought of before. Not too long ago, the concept of streaming services was simply unimaginable. Nobody was coming up with the idea of offering streaming video on demand because the infrastructure didn't exist.

We kind of need to be looking in different places here on Earth to fit these three different niches.

I wonder what thought has been given to using specific orbits for specific purposes. Many of the concepts for space-based infrastructure focuses on what to do in an essentially frozen orbit, but orbits don't have to be frozen. What if you placed your infrastructure in an eccentric orbit with a periapsis on the daylit side (with some sort of approach that uses precession to keep it there) in order to maximize the amount of time spent in Earth's shadow? Would those "free" heating and cooling cycles be useful for anything?   

26 minutes ago, tater said:

His case closed for high-cost power delivery to certain places like remote military bases in the arctic with 100% of the launches sourced with Atlas Vs at 2-3X the cost of a retail F9 launch.

The phased arrays on Starlink satellites can target 12" x 19" receiving dishes (although obviously the signal is significantly overlapping the receiver). I wonder if it would someday be possible to safely beam power to moving vehicles on the ground. Even if you coated every inch of a Tesla with solar cells, it wouldn't pick up enough power to recharge as it drives. But if you had a large space-based power generation array that was collecting many thousands of square meters of sunlight and beaming it directly to individual vehicles, that might work.

The United States sorely lacks interstate mass transit infrastructure, and bus tickets are terribly expensive in part due to the cost of fuel. If you could beam power directly to the roof of an electric bus so that it would never need to stop and recharge batteries, you could slash transit costs.

26 minutes ago, Exoscientist said:

Raptors have leaked fuel and caught fire multiple times during relights in the Starship tests

This was literally a completely different Raptor iteration.

[tater]

Atlas V 551 is $153M, F9 is ~$67M.

Atlas V 551 is 18.8t  to LEO, or ~$8100/kg. F9 is about half that w/reuse at ~$4200/kg (assuming just 16k to LEO). So to make that solar concept work vs terrestrial power (still cheaper to put the PVs on Earth, lol), Starship would need to come in closer to $800/kg. At ~150t to LEO, that would require a retail launch cost of ~120M.

[sevenperforce]

8 minutes ago, sevenperforce said:

What if you placed your infrastructure in an eccentric orbit with a periapsis on the daylit side (with some sort of approach that uses precession to keep it there) in order to maximize the amount of time spent in Earth's shadow? Would those "free" heating and cooling cycles be useful for anything?

35 minutes ago, tater said:

double-sided PVs that also have transmission in the layers (phased array) to function as orbital PV supply

The phased arrays on Starlink satellites can target 12" x 19" receiving dishes (although obviously the signal is significantly overlapping the receiver). I wonder if it would someday be possible to safely beam power to moving vehicles on the ground.

It just occurred to me that if you can place a satellite in a Molniya-style orbit to keep it in the sun's shadow as much as possible, you can also place it in an opposite orbit that keeps it in sunlight as much as possible. If they were able to solve linear losses in phased-array beaming (or at least partially solve them) then the extra distance wouldn't be a problem.

I'm reminded of the deep space telescopes that use lasers to create a guide star to adjust for atmospheric diffraction:

What if the phased array power transmitter and the corresponding receiver could communicate information about the shape of the power beam in order to use the phased array to adjust for atmospheric diffraction and reduce transmission losses? 

[tater]

There's a vid from some video or podcast with a couple random guys where they interview Musk, and they asked how much money was burned on IFT-1. He said the stack was at least $50m, maybe as much as $100M.

So the current Starship stack is maybe $100M a pop (expended).

Just now, sevenperforce said:

What if the phased array power transmitter and the corresponding receiver could communicate information about the shape of the power beam in order to use the phased array to adjust for atmospheric diffraction and reduce transmission losses? 

Interesting. There really needs to be more work on beamed power generally, it's a useful tech for space applications.

[Exoscientist]

34 minutes ago, tater said:

You have literally no idea why the engine did not relight. Nor do I. The people with all the telemetry data, who actually know how Raptor works? I assume they have a somewhat better idea than we have about it.

BTW, Zack Golden pointed out in his recent video that the frame of video where a flash is first seen—the bright pixels are exactly where the SH FTS is. In that case the flip caused engines outs due to starvation (see video you quoted for a possible visualization), flight path was computed to be off-nominal, FTS unzipped the vehicle.

 SpaceX in an update acknowledged that FTS was activated on the Starship but only said about the booster it was a RUD. This implies, though doesn’t prove, that it wasn’t the FTS that caused destruction of the booster. Scott Manley takes it as  meaning the FTS wasn’t activated on the booster. It’s possible it was both in that engines caused fires on the booster then the FTS was activated. Still it would be odd SpaceX would not say that directly if that happened when they did acknowledge it did for the Starship.

  Bob Clark

Edited November 28, 2023 by Exoscientist

[tater]

1 minute ago, Exoscientist said:

 Space in an update acknowledged that FTS was activated on the Starship but only said about the booster it was a RUD. This implies, though doesn’t prove, that it wasn’t the FTS that caused destruction of the booster. Scott Manley takes it as  meaning the FTS wasn’t activated on the booster. It’s possible it was both in that engines caused fires on the booster then the FTS was activated. Still it would be odd SpaceX would not say that directed if that happened when they did acknowledge it did for the Starship.

Fair point on talking about the booster, though it's odd that it was exactly where the FTS package is. Course that location was not picked randomly, either (presumably at common dome).

[RKunze]

28 minutes ago, sevenperforce said:

But if you had a large space-based power generation array that was collecting many thousands of square meters of sunlight and beaming it directly to individual vehicles, that might work.

It might work technically, but you definitely don't want to. Because concentrating multiple megawatts (i.e. what you get from "thousands of square meters of sunlight") on a couple of square meters (the size of an individual vehicle) results in an energy density that is way out in instant death ray territory...

Edited November 28, 2023 by RKunze

[darthgently]

36 minutes ago, Exoscientist said:

 SpaceX in an update acknowledged that FTS was activated on the Starship but only said about the booster it was a RUD. This implies, though doesn’t prove, that it wasn’t the FTS that caused destruction of the booster. Scott Manley takes it as  meaning the FTS wasn’t activated on the booster. It’s possible it was both in that engines caused fires on the booster then the FTS was activated. Still it would be odd SpaceX would not say that directly if that happened when they did acknowledge it did for the Starship.

  Bob Clark

They may not know if telemetry was lost due to damage whether auto-FTS kicked in locally, or RUD.  This is if the code on the rocket can make an FTS decision without ground input; which I think is the case, but not sure

[tater]

14 minutes ago, darthgently said:

They may not know if telemetry was lost due to damage whether auto-FTS kicked in locally, or RUD.  This is if the code on the rocket can make an FTS decision without ground input; which I think is the case, but not sure

SpaceX went to automated FTS a long time ago (per Space Force's ideal). if the vehicle was underperforming, or on a bad trajectory it could unzip.

 

Last night's launch:

 

[darthgently]

4 minutes ago, tater said:

SpaceX went to automated FTS a long time ago (per Space Force's ideal). if the vehicle was underperforming, or on a bad trajectory it could unzip.

That was my understanding, but wasn't sure.  So they may simply not know for certain if it was RUD or FTS trigger yet.  Unless the FTS sends out a radio signal prior to activation that perhaps uses its own independent radio hardware for robustness, they may not be certain

[RCgothic]

And even if an engine exploded, it's not necessarily the fault of the engine. E.g. fuel starvation causing turbine overspeed, or the control system getting fragged by shrapnel from a pressurised line failing.

SpaceX are the people with the data.

[tater]

14 minutes ago, RCgothic said:

And even if an engine exploded, it's not necessarily the fault of the engine. E.g. fuel starvation causing turbine overspeed, or the control system getting fragged by shrapnel from a pressurised line failing.

SpaceX are the people with the data.

Yeah, we have to wait for some after action report from Elon or SpaceX.

[Exoscientist]

This frame-by-frame vid of the booster explosion by Everyday Astronaut appears to show small explosions near the engine section prior to the area near the FTS exploding:

 

https://www.reddit.com/r/spacex/s/C7DsdctSgR

 Robert Clark

[darthgently]

16 minutes ago, Exoscientist said:

This frame-by-frame vid of the booster explosion by Everyday Astronaut appears to show small explosions near the engine section prior to the area near the FTS exploding:

 

https://www.reddit.com/r/spacex/s/C7DsdctSgR

 Robert Clark

It seems relatively safe to assume starvation and pump issues given

1) All engines ran fantastically from ground through stage separation until...

2) Extreme maneuvers happened

Therefore highly unlikely to be engine issues, but rather feed issues