totm nov 2023 SpaceX Discussion Thread

[YNM]

7 hours ago, NSEP said:

The BFR is Cryogenically fueled, meaning that you need to refuel it right before launch before it warms up and boils off. Refuelling such a thing takes up quite a bit if time, so if you were to strike back, there is a big chance you will be late. Also, ICBM's are usually made to be small, compact and have the ability to launch anytime. So using the BFR as ICBM is as practical as sending 150 Ford Fiestas into space. Just because you can does not mean its practical.

But they're not going to look different from a radar right ?

 

Again, just one possible problem... If anyone needs a reminder, it's good to have reminders. And some more.

 

--------

Regarding living on Mars :

Colonies are always fed. Until they get hold of their own feet. It wasn't easy in the 1500s, even on Earth ; it hasn't gone easier today or anytime in the near future (<20 yrs) for the outer space. Literally we're still doing baby steps.

[sevenperforce]

17 minutes ago, tater said:

Quote

Back to more "reasonable" stuff, one issue with BFR is that its serious overkill for most satellite launches.

That's the thing, it's NOT.

It's hard not to look at something bigger than Saturn V and not think, "overkill." But "overkill" in launching has exactly one metric. Cost.

If the cost per launch is a few million dollars, then it is only overkill compared to an expendable that costs less. Say it's 4M$/launch. If Vector or someone can launch your tiny sat for 2 M$, then yeah, don't hire a BFR all to yourself to launch. Of course if your sat could be slightly heavier with maneuvering such that it could comanifest and still launch for 100k, then you'd be silly not to do that, instead.

I mean, if SpaceX can REALLY manage to launch BFR for under $11 million*, including fuel, operating, logistics, payroll, and amortization...then yeah, this changes everything. You don't even need high volume.

I'll believe it when I see it, though. 

^{*(Falcon 1e was advertised at $11 million.)}

Inclination changes are tricky for multi-manifesting, of course.

EDIT: Of course, launching BFR at that kind of price does require SOME minimum volume.

Edited October 1, 2017 by sevenperforce

[tater]

8 minutes ago, sevenperforce said:

I mean, if SpaceX can REALLY manage to launch BFR for under $11 million*, including fuel, operating, logistics, payroll, and amortization...then yeah, this changes everything. You don't even need high volume.

I'll believe it when I see it, though. 

^{*(Falcon 1e was advertised at $11 million.)}

Inclination changes are tricky for multi-manifesting, of course.

They say 1000 launches for the booster, and 100 for the tanker/cargo.

That's on the order of a couple million (literally 2M) per launch in vehicle cost.

Propellant and operations from 2016 was 0.9M for the 2 together. 

We're at 3 million cost, 6M with a tank up. I'll also believe it when I see it, but it is truly transformative. It;s important to recognize that Bezos does the same math, hence the "overbuilt" NG. He says explicitly they are designing that way to fly it like an aircraft.

[sevenperforce]

5 minutes ago, tater said:

They say 1000 launches for the booster, and 100 for the tanker/cargo.

That's on the order of a couple million (literally 2M) per launch in vehicle cost.

Propellant and operations from 2016 was 0.9M for the 2 together. 

We're at 3 million cost, 6M with a tank up. I'll also believe it when I see it, but it is truly transformative. It;s important to recognize that Bezos does the same math, hence the "overbuilt" NG. He says explicitly they are designing that way to fly it like an aircraft.

I had originally thought "hmm, they could drop it to 8 meter" but then again New Glenn is 7 meters, so...

[kerbiloid]

2 minutes ago, Steel said:

My question, how do you persuade so many people to go?

Me? No how. I was just talking about the oxygen.

P.S.
A new name for this thread: "Space-X: before and after".
"Before" and "after" the BFR presentation, of course.

Edited October 1, 2017 by kerbiloid

[Steel]

Just now, kerbiloid said:

Me? No how. I was just talking about the oxygen.

Yeah sorry, one of your quotes snuck it's way in some how!

[StrandedonEarth]

5 hours ago, tater said:

BFS cargo goes to GEO with a new sat or sats. Inside, they put an arm, and some system to grapple a few defunct sats inside the bay safely.

Concern would obviously be reentry, right? Hard to really bolt them down. So you don't.

BFS does a burn to drop perigee deep into the atmosphere in prep for aerobraking/reentry from GEO. Open (if it was even closed) cargo bay. Dump defunct sats. Close cargo bay, raise perigee to one appropriate for entry and landing. You've just disposed of a bunch of space junk.

I hate to see mass on orbit get wasted, especially manufactured goods. I'm all for recovering them, and moving them to a central depot (especially easy for GSO comsats) until they can eventually be "processed." This would include disassembling, fixing, scavenging/cannibalizing/recovering components, repurposing, and eventually (as a last resort) recycling and remanufacturing. A lot of dead comsats could probably be revived with new batteries, greased/lubed reaction wheels, and/or a propellant refill. This is where having a human with hands-on is invaluable, to do the things that robotics simply can't*. Possibilities range from connecting all the recovered PV's into large power arrays, to reshaping metal panels into huge solar collectors for smelters, as capabilities increase. A use could always be found for the electronics.

*Yes, robotics can and will do a lot, and telerobotics  would be even more capable. I don't know where the bleeding edge of telerobotic tech is right now, but I'm pretty sure nothing will ever completely match a human's combination of tactile feedback processing with give-it-just-the-right-whack problem-solving, although robotic dexterity can probably surpass human. Humans don't even need to be a permanent presence, they would just need visit now and then to deal with the stockpile of stubborn equipment that the robots put aside.

2 hours ago, regex said:

Wasn't there some speculation that a single asteroid could pretty much crash the Earth mineral markets? That is, as soon as you introduce that much raw material to Earth economies its worth becomes pretty meaningless. Wealth takes on whole new meanings and you start pondering the realms of post-scarcity. BFR may make that future a reality with so much mass on orbit so cheaply.

I regret that I only have one like to give to this. Forget Mars for now; IMO this is what the true goal of space exploration should be: finding easily accessible chunks of space metal to mine, before Earth's more accessible deposits are mined out and thrown away, and we're forced to dig deeper (at greater energy and pollution costs) for our resources. The energy to power a miner-refiner is free for the taking, once we build the collectors, ideally from materials already in space. One way to turn prospecting spaceward would be to increase permit taxes or enforce expensive pollution-prevention measures, making space more economically attractive. Whoops, this is where politics come in. 

I can't help but wonder how much Earth could be transformed by finding an asteroid containing mega-tons of platinum. It appears to be one of the best catalysts out there for many desirable processes, especially but not limited to fuel cells. Millions of dollars are poured into research to find alternate catalysts, using less platinum, because platinum is just so diabolically expensive. Imagine the possibilities if platinum (roughly the same price as gold, depending on the market) cost the same as silver, or perhaps the same as copper or other base metals. I'd love to have a natural-gas fuel cell in my home; having them commonplace would revolutionize power grids and generation, and provide redundancy. But they're just too expensive to be economical.

This train of thought has taken the scenic route, but it is finally getting to the topic: the potential economies of scale (and re-usability!) offered by BFR and New Glenn are essential to getting the equipment required for space industry (most importantly mining!) off the ground.

in the family-life time it has taken me to compose this post, there have been at least 18 new posts in this thread. Wouldn't it be great if there was a thread for "The Case for Mars" and probably another for "The Case for Luna"?
 

Edited October 1, 2017 by StrandedonEarth
tweak, tweak, tweak

[tater]

Musk advocates at the very least serious work on AGI safety, while holding AI as an existential threat to humanity. I actually buy the argument about the importance of safety in this area of human tech development. 

All that said, if AGI is possible in the next 50-100 years, then putting off colonization until then makes a lot of sense, since it would take so long to become self sufficient that you might leapfrog that by letting someone smarter work it out (that someone being the AGI).

[Spaceception]

Pretty good overview about the BFR, and the danger/risks they will have to watch out for, the comments are decent to, at least the top one, im still working my way down

https://amp.reddit.com/r/spacex/comments/73mryo/full_analysis_of_spacex_plan_20/

[harrisjosh2711]

Has SpaceX discussed exactly how the BFR is going to slow down? Elon said he was confident they could kill 98% of momentum with solely aerodynamics, I believe. 

I have accomplished it by having my BFR flip during descent straight into its landing position, where it actually flies backwards.- Check it out-

 

[cubinator]

11 minutes ago, harrisjosh2711 said:

Has SpaceX discussed exactly how the BFR is going to slow down? Elon said he was confident they could kill 98% of momentum with solely aerodynamics, I believe. 

I have accomplished it by having my BFR flip during descent straight into its landing position, where it actually flies backwards.- Check it out-

 

1. That's a lot of gees. I wouldn't want to experience a sudden bout of over 10 g while landing from a hyperbolic trajectory, and the spacecraft probably wouldn't like it either.

2. Once flipped, the engines are getting a lot of force and heat that they don't want.

Overall, I prefer a more gradual deceleration. Elon did show an animated physics simulation during his presentation that showed the trajectory that BFR would fly while entering Mars' atmosphere.

[harrisjosh2711]

3 minutes ago, cubinator said:

1. That's a lot of gees. I wouldn't want to experience a sudden bout of over 10 g while landing from a hyperbolic trajectory, and the spacecraft probably wouldn't like it either.

2. Once flipped, the engines are getting a lot of force and heat that they don't want.

Overall, I prefer a more gradual deceleration. Elon did show an animated physics simulation during his presentation that showed the trajectory that BFR would fly while entering Mars' atmosphere.

In kerbal terms it really doesn't seem that bad. From a real world perspective, I can say I didn't account for the extra 6000 ms (give or take) I would be traveling during return.

Oh, come on- everyone would like to get hit with a sudden impact of 10G's every once in awhile. Don't be such a wuss.

[tater]

 

[cubinator]

15 minutes ago, harrisjosh2711 said:

Oh, come on- everyone would like to get hit with a sudden impact of 10G's every once in awhile. Don't be such a wuss.

Yeah but I'm already hurtling towards an alien planet at thousands of m/s and will die if the ship doesn't point the right way, the engines stop working and don't fire at exactly the right time, or the landing gear fail. I don't need the wind knocked out of me on top of that.

Edited October 2, 2017 by cubinator

[harrisjosh2711]

2 minutes ago, cubinator said:

Yeah but I'm already hurtling towards an alien planet at thousands of m/s and will die if the ship doesn't point the right way, the engines stop working and don't fire at exactly the right time, or the landing gear fail. I don't need the wind knocked out of me on top of that.

That statement was meant to be read as sarcastic. It did get me interested though. It turns out while 10G is a lot. Its no where near the human limit. Especially, since that amount of force is exerted for less than a second. There are accounts of humans surviving over 100g's in accidents. The best reference I could find was, experiencing 16g's for over a minute  could potentially be deadly for humans; especially if vibration is present. Special seats and suits are, and could be further developed to combat the effects. 

I'm not sure how G's relate in KSP to real the world though. I will make it real size likely when and if Realism-overhaul ever catches up to the fold.

[cubinator]

8 minutes ago, harrisjosh2711 said:

That statement was meant to be read as sarcastic. It did get me interested though. It turns out while 10G is a lot. Its no where near the human limit. Especially, since that amount of force is exerted for less than a second. There are accounts of humans surviving over 100g's in accidents. The best reference I could find was, experiencing 16g's for over a minute  could potentially be deadly for humans; especially if vibration is present. Special seats and suits are, and could be further developed to combat the effects. 

I did catch the sarcasm. It sounds like Mars entry would be around 4-6 g normally, but still, that counter was over 10 and it would likely be much more at a higher entry speed, so it's still potential for at least unconsciousness (spinning backwards for a red-out?) which is not something you want when about to land in a spaceship.

Quote

 

 

[harrisjosh2711]

33 minutes ago, cubinator said:

I did catch the sarcasm. It sounds like Mars entry would be around 4-6 g normally, but still, that counter was over 10 and it would likely be much more at a higher entry speed, so it's still potential for at least unconsciousness (spinning backwards for a red-out?) which is not something you want when about to land in a spaceship.

 

Ill have to test it, but I took a very steep angle of descent. As who wants to watch a 3:30 second landing video? I meant slow down fast. I had extra fuel so I could have slowed ever further with the engines before entrance or took a much less steep angle and used a lot more atmosphere to slow me down. I really didn't do this because the lift on the ship would make it very difficult to land anywhere near kerbin, as you can see I missed it even with a steep angle of attack. The purpose of this test was to kill 98% of velocity with nothing but aerodynamics in a 55 ton (dry mass) vehicle. I did that. 

I do completely understand your concern though. And it is your choice if you would like to fly on my rocket to ...............

[harrisjosh2711]

@cubinator It was only the angle of attack that the flip so strong. Under normal conditions the G's don't exceed more than 5.

[aluc24]

Guys, how do you feel about Elon's promises to get people to Mars by 2024, and the recent announcement about rockets replacing planes for worldwide travel? I love Elon and everything, but I must say, some of this stuff really pushes what I can believe. The timeframe is just too unrealistic in my opinion. What do you think?

[Nibb31]

7 minutes ago, aluc24 said:

Guys, how do you feel about Elon's promises to get people to Mars by 2024, and the recent announcement about rockets replacing planes for worldwide travel? I love Elon and everything, but I must say, some of this stuff really pushes what I can believe. The timeframe is just too unrealistic in my opinion. What do you think?

Why are you asking this question when this is precisely what we have been talking about for the last couple of days ? Didn't you bother to read the last 15 pages of the thread ?

[Green Baron]

2024 ? Someone should have a suitable rocket by now and at least a vague idea of how to keep people alive on the trip there, a prolonged stay, and a trip back. That is how long all in all ?

Anyone sees any of these things happen ?

The vehicle is on (slightly under) the horizon since ... a long time, ever being postponed, lastly even principally questioned. The ITS, announced as a big thing, is scrubbed, the ITSy, development starts "in 5-6 months" :-)) How long does it take to develop a rocket with new technologies ? 10-20 years ?

So, short version, ridiculous, long version, not going to happen.

 

2040-50. Musk ? Nasa ? China ? ... who knows :-)

 

Edit: so now you know my opinion about all that has been said and written above and in the many similar discussions before.

Edited October 2, 2017 by Green Baron

[aluc24]

5 minutes ago, Nibb31 said:

Why are you asking this question when this is precisely what we have been talking about for the last couple of days ? Didn't you bother to read the last 15 pages of the thread ?

Forgive me. I only read like 5, and seeing that the discussion is about something else (or so I thought), assumed this specific question hasn't been discussed yet. My bad.

Edited October 2, 2017 by aluc24

[Green Baron]

Anyway, the whole thing is repetitive and speculative so the lack of concentration is forgiven :-)

*duckandcover*

 

Edit: experience shows that if a complex project gets shifted forward too often then it'll never be finished. That may be because funds running out, technology not ready, risks incalculable or dwindling overall support. Or a combination thereof.

Edited October 2, 2017 by Green Baron

[Nefrums]

About the supposedly reusable heat shield on the BFR ship, are there any examples of heat shields that have been reused without extensive refurbishment today? 

 

[aluc24]

11 minutes ago, Green Baron said:

Anyway, the whole thing is repetitive and speculative so the lack of concentration is forgiven :-)

*duckandcover*

 

Thanks... As I'm looking through all these posts, I still can't understand one thing: if this whole thing is so unrealistic (and Elon must know this!), then why the hell is he making these outlandish, utopian promises? SpaceX always seemed like the company of action, not fraud.