Author Topic: TED talk by Gwynne Shotwell (April 2018)  (Read 44009 times)

Offline Semmel

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TED talk by Gwynne Shotwell (April 2018)
« on: 04/13/2018 10:40 AM »
The recent TED talk by Gwynne Shotwell is not available online just yet but we have still a lot of discussion about it, which is polluting the "upcoming talks" thread starting here:

https://ted2018.ted.com/speakers#gwynne-shotwell

Gwynne Shotwell at TED

This thread is for discussing the content of the talk.

edit: Video is now available:
https://www.ted.com/talks/gwynne_shotwell_spacex_s_plan_to_fly_you_across_the_globe_in_30_minutes
« Last Edit: 10/04/2018 02:24 PM by gongora »

Online docmordrid

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Re: TED talk by Gwynne Shotwell
« Reply #1 on: 04/13/2018 10:58 AM »
Erik Cleven @VoltzCoreAudio
Replying to @elonmusk and 3 others
Has the BFR/BFS been stretched in height? The video Gwynne showed at Ted Talks looks taller than the one in the E2E video

Elon Musk ✔ @elonmusk
Maybe a little 😉
3:09 AM - Apr 13, 2018

G C @SmileSimplify
Replying to @elonmusk and 2 others
Which section/stage was stretched: 1st or 2nd or both stages?

Erik Cleven @VoltzCoreAudio
Possibly both according to this pic.twitter.com/VWR4L6Kpez
3:27 AM - Apr 13, 2018


Offline FlokiViking

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Re: TED talk by Gwynne Shotwell
« Reply #2 on: 04/13/2018 02:33 PM »
From those pictures a bit hard to tell, but maybe a couple of other changes?
- relative size of wing at base of BFS looks a bit smaller
- BFS nose looks less bi-conic, more conical
If correct, could reflect significant refinement of control laws.
« Last Edit: 04/13/2018 02:37 PM by FlokiViking »

Online DistantTemple

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Re: TED talk by Gwynne Shotwell
« Reply #3 on: 04/13/2018 02:56 PM »
Elon "confirms" it... somewhat flexibly.

says "Maybe a little" as the last shown reply at the bottom.
« Last Edit: 04/13/2018 02:57 PM by DistantTemple »
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Online ZachF

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Re: TED talk by Gwynne Shotwell
« Reply #4 on: 04/13/2018 03:29 PM »
In order to stretch the length they'd need pretty much a corresponding increase in Raptor chamber pressure. (Provided everything else stays the same at least)

Perhaps Raptor development goes (or continues to go?) better than anticipated? 300 bar back on the table?
« Last Edit: 04/13/2018 03:32 PM by ZachF »

Online AncientU

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Re: TED talk by Gwynne Shotwell
« Reply #5 on: 04/13/2018 03:38 PM »
If that stretch is around 20%, that could put Raptor above 2MN, 450klbf.
That's a beast of an engine.
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Offline KSC Sage

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Re: TED talk by Gwynne Shotwell
« Reply #6 on: 04/13/2018 03:50 PM »
Erik Cleven @VoltzCoreAudio
Replying to @elonmusk and 3 others
Has the BFR/BFS been stretched in height? The video Gwynne showed at Ted Talks looks taller than the one in the E2E video

Elon Musk ✔ @elonmusk
Maybe a little 😉
3:09 AM - Apr 13, 2018

G C @SmileSimplify
Replying to @elonmusk and 2 others
Which section/stage was stretched: 1st or 2nd or both stages?

Erik Cleven @VoltzCoreAudio
Possibly both according to this pic.twitter.com/VWR4L6Kpez
3:27 AM - Apr 13, 2018


Be careful not to read too much into those images.  It looks like the aspect ratio is off on those images which causes the BFR to looked stretched.  I doubt at this stage of the design the OML will change very much.

Re: TED talk by Gwynne Shotwell
« Reply #7 on: 04/13/2018 03:51 PM »
u/Intro24 on Reddit used an un-distorted image to get a better size comparison.

https://www.reddit.com/r/SpaceXLounge/comments/8bznue/bfr_2018_size_comparison/

Looks like its just taller than the Saturn V (Elon couldn't let that slide  ;)). Also to me it looks like the legs sit in a little tube that extends past the ship to the booster. My theory is that the pushers that will separate the stages sit inside the tubes that are on the booster and will push against the bottom of the legs, instead of having separate points like Falcon 9.

Thoughts?

Online ZachF

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Re: TED talk by Gwynne Shotwell
« Reply #8 on: 04/13/2018 03:56 PM »
u/Intro24 on Reddit used an un-distorted image to get a better size comparison.

https://www.reddit.com/r/SpaceXLounge/comments/8bznue/bfr_2018_size_comparison/

Looks like its just taller than the Saturn V (Elon couldn't let that slide  ;)). Also to me it looks like the legs sit in a little tube that extends past the ship to the booster. My theory is that the pushers that will separate the stages sit inside the tubes that are on the booster and will push against the bottom of the legs, instead of having separate points like Falcon 9.

Thoughts?

One thing that's noticeably different is the orientation of the grid fins and the leg nacelles(?).
« Last Edit: 04/13/2018 04:13 PM by ZachF »

Offline Elmar Moelzer

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Re: TED talk by Gwynne Shotwell
« Reply #9 on: 04/13/2018 04:14 PM »
I don't think it has been stretched much. The video is completely distorted by the angle. So it is most likely just looking a bit squished.

Offline Jdeshetler

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Re: TED talk by Gwynne Shotwell
« Reply #10 on: 04/13/2018 05:11 PM »
This stabilized video was crudely widened until the water tower was proportional correct.


Offline DanielW

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Re: TED talk by Gwynne Shotwell
« Reply #11 on: 04/13/2018 06:52 PM »
u/Intro24 on Reddit used an un-distorted image to get a better size comparison.

https://www.reddit.com/r/SpaceXLounge/comments/8bznue/bfr_2018_size_comparison/

Looks like its just taller than the Saturn V (Elon couldn't let that slide  ;)). Also to me it looks like the legs sit in a little tube that extends past the ship to the booster. My theory is that the pushers that will separate the stages sit inside the tubes that are on the booster and will push against the bottom of the legs, instead of having separate points like Falcon 9.

Thoughts?

Just use the legs as the pushers? they need to be able to extend and retract reliably anyway.

Offline DJPledger

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Re: TED talk by Gwynne Shotwell
« Reply #12 on: 04/13/2018 07:19 PM »
If that stretch is around 20%, that could put Raptor above 2MN, 450klbf.
That's a beast of an engine.
31 engines is not optimal packing density on the booster. There is room for improvement to the engine packing density and hence thrust density by either going with 37 (1,6,12,18) Raptors of the same physical size as the dev. raptor operating at 25MPa or higher or 19 (1,6,12) larger Raptors of c.3MN at SL operating at the same pressure. Using dev. raptor size for ship will allow for greater engine out capability by requiring more engines. Raptor may be easier to scale than 1st thought and can be produced in multiple sizes without too much cost and difficulty. Optimizing engine packing density on booster will allow for a stretch without having to increase Raptor Pc. Further booster stretching can of course be facilitated by increasing Raptor Pc. which is a long term goal.

Don't be surprised if the Raptor no. on the booster changes again in the next BFR update.

Offline philw1776

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Re: TED talk by Gwynne Shotwell
« Reply #13 on: 04/13/2018 10:23 PM »
If that stretch is around 20%, that could put Raptor above 2MN, 450klbf.
That's a beast of an engine.
31 engines is not optimal packing density on the booster. There is room for improvement to the engine packing density and hence thrust density by either going with 37 (1,6,12,18) Raptors of the same physical size as the dev. raptor operating at 25MPa or higher or 19 (1,6,12) larger Raptors of c.3MN at SL operating at the same pressure. Using dev. raptor size for ship will allow for greater engine out capability by requiring more engines. Raptor may be easier to scale than 1st thought and can be produced in multiple sizes without too much cost and difficulty. Optimizing engine packing density on booster will allow for a stretch without having to increase Raptor Pc. Further booster stretching can of course be facilitated by increasing Raptor Pc. which is a long term goal.

Don't be surprised if the Raptor no. on the booster changes again in the next BFR update.

Could not agree more. I guessed correctly that Raptor would be upscaled in 2016 IAC and it was.  Missed the 2017 downscale.  It's a work in process but until development matures more, it's subject to spec change.
Then you have the SpaceX/Mueller DNA that greatly improves an engine for generations after first flight protos.
ďWhen it looks more like an alien dreadnought, thatís when you know youíve won.Ē

Offline OneSpeed

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Re: TED talk by Gwynne Shotwell
« Reply #14 on: 04/14/2018 12:46 AM »
Erik Cleven @VoltzCoreAudio
Replying to @elonmusk and 3 others
Has the BFR/BFS been stretched in height? The video Gwynne showed at Ted Talks looks taller than the one in the E2E video

Elon Musk ✔ @elonmusk
Maybe a little 😉
3:09 AM - Apr 13, 2018

Here is a comparison between stills from the IAC Adelaide presentation and Jdeshetler's stabilised video. If there is a difference, it's very small.

Online DistantTemple

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Re: TED talk by Gwynne Shotwell
« Reply #15 on: 04/14/2018 01:21 AM »
Erik Cleven @VoltzCoreAudio
Replying to @elonmusk and 3 others
Has the BFR/BFS been stretched in height? The video Gwynne showed at Ted Talks looks taller than the one in the E2E video

Elon Musk ✔ @elonmusk
Maybe a little
3:09 AM - Apr 13, 2018
Here is a comparison between stills from the IAC Adelaide presentation and Jdeshetler's stabilised video. If there is a difference, it's very small.
The height of the camera is different and in the right hand picture, and the perspective is different, the right tower appears closer to the camera than the BFR, whereas in the left one they are level. Thus with as you say a small difference, its not clear enough to make a determination. But as EM says, "Maybe a little" and that little probably just happens to make it the "Biggest Rocket Ever" with no qualification of "since the Satern V".... I bet he has stretched it, and he would absolutely know, and "Maybe a little" is him having fun.
« Last Edit: 04/14/2018 01:23 AM by DistantTemple »
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Offline Elmar Moelzer

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Re: TED talk by Gwynne Shotwell
« Reply #16 on: 04/14/2018 02:55 AM »
If it was streched, then all the wings/bulges were stretched by about the same amount. I am not sure that that would actually happen. I still think that this was just an optical illusion caused by the perspective of the camera that filed the video of the screen.

Offline DigitalMan

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Re: TED talk by Gwynne Shotwell
« Reply #17 on: 04/14/2018 05:27 AM »
I suspect from that tweet that it hasnít stretched at all except perhaps some trivial amount

Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #18 on: 04/14/2018 06:42 AM »
I suspect from that tweet that it hasnít stretched at all except perhaps some trivial amount

I'm reminded of the tweet
Quote
Under consideration. Weíve already stretched the upper stage once. Easiest part of the rocket to change. Fairing 2, flying soon, also has a slightly larger diameter. Could make fairing much longer if need be & will if BFR takes longer than expected.

When it turned out to be 2.5% larger in diameter.
« Last Edit: 04/14/2018 06:44 AM by speedevil »

Online Lars-J

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TED talk by Gwynne Shotwell
« Reply #19 on: 04/14/2018 06:49 AM »
I suspect from that tweet that it hasnít stretched at all except perhaps some trivial amount

Thatís my impression as well. People who are analyzing these terrible quality images and coming up with a much bigger BFS should stay away from image analysis.

And speedevil is right... everyone was jazzed about the bigger fairing that ended up being ~2% larger.
« Last Edit: 04/14/2018 06:51 AM by Lars-J »

Offline deruch

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Re: TED talk by Gwynne Shotwell
« Reply #20 on: 04/14/2018 08:38 AM »
And speedevil is right... everyone was jazzed about the bigger fairing that ended up being ~2% larger.

I was totally jazzed by that 2% because it enabled my pet thought experiment mission which needed a payload envelope 4 inches wider than Fairing 1.0 allowed.  Now that mission is only impossible for 2 reasons instead of 3.  Woot! Slowly hurdling those obstacles.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline kevinof

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Re: TED talk by Gwynne Shotwell
« Reply #21 on: 04/14/2018 09:11 AM »
Ok, I'll bite. What payload?

And speedevil is right... everyone was jazzed about the bigger fairing that ended up being ~2% larger.

I was totally jazzed by that 2% because it enabled my pet thought experiment mission which needed a payload envelope 4 inches wider than Fairing 1.0 allowed.  Now that mission is only impossible for 2 reasons instead of 3.  Woot! Slowly hurdling those obstacles.

Offline deruch

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Re: TED talk by Gwynne Shotwell
« Reply #22 on: 04/15/2018 04:30 AM »
Ok, I'll bite. What payload?

It was me trying to kill 2 birds with one stone.  The idea was to enable an essentially free launch of an only slightly modified LDSD on a used booster.  It would find a use for the extra boosters that SpaceX seemed to have laying around gathering dust--which problem has since been somewhat mitigated by the fact that they have foregone recovery on multiple recent missions--while also potentially enabling an important project that had been criminally underfunded.  (This was also originally thought of before so many customers accepted flight proven boosters, so it was also to be another data point in proving that reuse was feasible)

While the LDSD was eventually launched via balloon drop + solid kick motor, in earlier mission design studies they considered launching it via Castor solid motors.  The problem was that they considered the danger of recontact with the expended motor post separation too great.  But that relied on the design that the Castors would accelerate the vehicle to the final mission velocity.  In my design, instead of trying to just swap the F9 booster for those solid motors, they would instead use it as an almost direct swap for the balloon.  Use the F9 booster just to get the same altitude as the balloon and leave the LDSD to finish acceleration to final velocity via an onboard solid kick motor.  That would eliminate the recontact issues as well as reduce the amount of vehicle redesign needed to enable the mission.  So, it would look like a very high altitude Grasshopper launch with the LDSD on top.

So, how does the fairing come into it, I hear you ask.  In order to limit the costs of redesigning the LDSD vehicle (since, before the funding was cut, they had one planned for further testing sitting around), one of the considerations was whether the LDSD could withstand the forces being applied to it in that manner/direction or what orientation it might need to be integrated in.  So, I thought that it might need to be launched within a fairing to limit such problems.  Only the LDSD had a diameter of 4.7m and the F9 fairing limited the payload envelope to 4.6m.  By this point I was also considering whether they would need to use some sort of dummy second stage, etc.
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Online flyright

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Re: TED talk by Gwynne Shotwell
« Reply #23 on: 04/15/2018 12:53 PM »
I had to look that one up.
Low-Density Supersonic Decelerator (LDSD).

Offline testguy

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Re: TED talk by Gwynne Shotwell
« Reply #24 on: 04/15/2018 03:09 PM »
I had to look that one up.
Low-Density Supersonic Decelerator (LDSD).

Thanks!  I glad I wasn't the only one scratching my head.

Offline Barrie

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Re: TED talk by Gwynne Shotwell
« Reply #25 on: 04/15/2018 07:58 PM »
Different emphasis in this report on Gwynne's talk:

Quote
At the 2018 TED Conference on Wednesday, SpaceX president Gwynne Shotwell seemed for the first time to express an even grander vision than Elon Musk's plan to colonize Mars.

Speaking to the crowd, Shotwell said she won't be content to land a SpaceX rocket on Mars, or even to reach more distant planets like Saturn or Pluto. Instead, she revealed that she ultimately hopes to meet up with whoever's out there in other solar systems.

"This is the first time I might out-vision Elon," she said of the SpaceX founder.

http://uk.businessinsider.com/spacex-president-gwynne-shotwell-ted-mars-is-a-fixer-upper-2018-4

Gwynne has in past talks mentioned her dreams of a future where travel to other solar systems is possible.

This aspect of the TED talk seems a bit less off-the-wall in the context of the upcoming TESS launch.

Offline FutureSpaceTourist

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Re: TED talk by Gwynne Shotwell
« Reply #26 on: 04/15/2018 08:18 PM »
Quote
Some new images of @SpaceX's Big Falcon Rocket (BFR) from SpaceX president&COO Gwynne Shotwell's presentation at #TED2018 conference here: http://www.humanmars.net/2018/04/spacex-big-falcon-rocket-launch-images.html

https://twitter.com/human_mars/status/985570953806532608

Offline deruch

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Re: TED talk by Gwynne Shotwell
« Reply #27 on: 04/16/2018 12:19 AM »
I had to look that one up.
Low-Density Supersonic Decelerator (LDSD).

Oops, sorry.  I usually remember to include the full name when using acronyms the first time.  My bad.  It was a project to test out a few new technologies to enable landing higher mass payloads on Mars by increasing the aerodynamic drag after atmospheric entry and enabling the use of large parachutes at supersonic speeds.  So it tested an inflatable ring that expanded the ballistic area of an entering capsule, some new larger supersonic parachute designs (they had plans to test 2 different designs), and a ballute instead of a drogue for stability and deployment of the parachutes. 
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline cro-magnon gramps

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Re: TED talk by Gwynne Shotwell
« Reply #28 on: 04/16/2018 09:07 AM »
Different emphasis in this report on Gwynne's talk:

Quote
At the 2018 TED Conference on Wednesday, SpaceX president Gwynne Shotwell seemed for the first time to express an even grander vision than Elon Musk's plan to colonize Mars.

Speaking to the crowd, Shotwell said she won't be content to land a SpaceX rocket on Mars, or even to reach more distant planets like Saturn or Pluto. Instead, she revealed that she ultimately hopes to meet up with whoever's out there in other solar systems.

"This is the first time I might out-vision Elon," she said of the SpaceX founder.

http://uk.businessinsider.com/spacex-president-gwynne-shotwell-ted-mars-is-a-fixer-upper-2018-4

Gwynne has in past talks mentioned her dreams of a future where travel to other solar systems is possible.

This aspect of the TED talk seems a bit less off-the-wall in the context of the upcoming TESS launch.


there was a panel discussion that she was involved in, 2015/16 time frame, when they were asked for their predictions 25 years out... her answer was out of the norm... she said, "I hope by then we are working on Interstellar Propulsion" presumably she meant SpaceX, as none of the other participants were anywhere near that optimistic or forward thinking... that really stuck with me, because she just sat there, with a 'like what did i say that's so unusual' look... 
"Hate, it has caused a lot of problems in the world, but it has not solved one yet." Maya Angelou
 Tony Benn: "Hope is the fuel of progress and fear is the prison in which you put yourself."

Offline Semmel

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Re: TED talk by Gwynne Shotwell
« Reply #29 on: 04/16/2018 09:43 AM »
there was a panel discussion that she was involved in, 2015/16 time frame, when they were asked for their predictions 25 years out... her answer was out of the norm... she said, "I hope by then we are working on Interstellar Propulsion" presumably she meant SpaceX, as none of the other participants were anywhere near that optimistic or forward thinking... that really stuck with me, because she just sat there, with a 'like what did i say that's so unusual' look...

I remember that well. I argues at the time that she doesnt understand what she is talking about. Talking about going to other stars is too much of a stretch.
Imagine its 3000BC, the local government at the Neil river just funded a new type of vehicle called a raft that can go over the Neil river to the other shore. It was a huge success and 50 years later, the first private company of raft builders offers regular service to transport goods over the Neil river. The local press interviews the guy who does it and asks where he sees river rafting in the next 25 years. Then he comes up with the answer that he hopes to work on rafts that swim the large darkness in order to visit the moon. Fast forward to today. We just are about able to get people to the moon. But going to another solar system is the same as our little raft builder going to the moon. Physically not impossible but way, way, way out of the current engineering capabilities.

Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #30 on: 04/16/2018 10:35 AM »
Physically not impossible but way, way, way out of the current engineering capabilities.

Interstellar propulsion does not mean humans.
There are at least several nearish-term-maybe moderate performance options that may do interesting things in the 'percent of c or so' range.
From dusty fission, to LASER pushed microprobes, to fusion.

Certainly, in 25 years, a mission to for example do a manned mission to Sedna might be very ambitious, but plausible, if everything has gone right.

Offline john smith 19

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Re: TED talk by Gwynne Shotwell
« Reply #31 on: 04/16/2018 10:40 AM »

there was a panel discussion that she was involved in, 2015/16 time frame, when they were asked for their predictions 25 years out... her answer was out of the norm... she said, "I hope by then we are working on Interstellar Propulsion" presumably she meant SpaceX, as none of the other participants were anywhere near that optimistic or forward thinking... that really stuck with me, because she just sat there, with a 'like what did i say that's so unusual' look...
Perhaps she sees the theoretical limits of the technology today, rather than the (much) more limited level we apply that technology?

An engine with an exhaust of 5-10% of the speed of light is possible today. No "breakthrough" physics involved. Just engineering.

[EDIT OTOH taking humans there is way tougher.
Then again without very solid evidence of a (approximately) Earth type planet to settle down on, or the ability to refuel and come home this is basically a suicide mission. My instinct is that closed cycle ECLSS and automation reliability have to get a lot better before humans can go.  It's just a very long time in space with very little to actually do. IMHO Keeping most (all?) the crew in some form of "suspended animation" is the only way to make it viable  ]
« Last Edit: 04/17/2018 03:53 PM by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline cro-magnon gramps

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Re: TED talk by Gwynne Shotwell
« Reply #32 on: 04/16/2018 01:39 PM »
https://forum.nasaspaceflight.com/index.php?topic=45008.msg1811022#msg1811022
Re: Will SpaceX using technology from Open AI
ę Reply #44 on: Today at 09:35 AM Ľ
I've posted a reply here, to keep this thread on topic
Please take any relevant discussions there... thx
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Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #33 on: 04/16/2018 01:39 PM »
Didn't someone say that Shotwell's video would be released today (the 16th)? I can't find it.
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Offline Semmel

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Re: TED talk by Gwynne Shotwell
« Reply #34 on: 04/16/2018 02:20 PM »
A more mundane possibility: Asking about stuff that would happen 20/35/50 years from now is a bit ridiculous from Gwynnes perspective. She is responsible for the economic success of SpaceX. She has necessarily a horizon of maybe 5 years or some more in some long term development projects. From her perspective, talking about stuff that is 4 to 10 times her current time horizon, there is no way she can give a sensible answer. So she gives intentionally a ridiculous one.

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #35 on: 04/16/2018 03:28 PM »
Didn't someone say that Shotwell's video would be released today (the 16th)? I can't find it.

https://tedlive.ted.com/webcasts/t2018/session/291

Cost is $25.

Offline llanitedave

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Re: TED talk by Gwynne Shotwell
« Reply #36 on: 04/16/2018 04:22 PM »
there was a panel discussion that she was involved in, 2015/16 time frame, when they were asked for their predictions 25 years out... her answer was out of the norm... she said, "I hope by then we are working on Interstellar Propulsion" presumably she meant SpaceX, as none of the other participants were anywhere near that optimistic or forward thinking... that really stuck with me, because she just sat there, with a 'like what did i say that's so unusual' look...

I remember that well. I argues at the time that she doesnt understand what she is talking about. Talking about going to other stars is too much of a stretch.
Imagine its 3000BC, the local government at the Neil river just funded a new type of vehicle called a raft that can go over the Neil river to the other shore. It was a huge success and 50 years later, the first private company of raft builders offers regular service to transport goods over the Neil river. The local press interviews the guy who does it and asks where he sees river rafting in the next 25 years. Then he comes up with the answer that he hopes to work on rafts that swim the large darkness in order to visit the moon. Fast forward to today. We just are about able to get people to the moon. But going to another solar system is the same as our little raft builder going to the moon. Physically not impossible but way, way, way out of the current engineering capabilities.


"Working on" doesn't mean "implementing".  I see that as an area of research that she hopes by then they can be investigating, not promising an imminent mission.
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Re: TED talk by Gwynne Shotwell
« Reply #37 on: 04/16/2018 05:11 PM »
there was a panel discussion that she was involved in, 2015/16 time frame, when they were asked for their predictions 25 years out... her answer was out of the norm... she said, "I hope by then we are working on Interstellar Propulsion" presumably she meant SpaceX, as none of the other participants were anywhere near that optimistic or forward thinking... that really stuck with me, because she just sat there, with a 'like what did i say that's so unusual' look...

I remember that well. I argues at the time that she doesnt understand what she is talking about. Talking about going to other stars is too much of a stretch.
... snip ...
Physically not impossible but way, way, way out of the current engineering capabilities.

"Working on" doesn't mean "implementing".  I see that as an area of research that she hopes by then they can be investigating, not promising an imminent mission.
Yes I agree ""Working on" doesn't mean "implementing"." And they could already be "working on" Interstellar Propulsion. Now! And GS is rather well placed to know exactly what she's talking about... perhaps that's more obvious today.
I think our minds are quite closed to the future... and the slow pace of space exploration these 50 years has reinforced that. Both Gwynne, and Elon almost have to use tin-openers on our thick heads, to get us to see whats really possible!

Recent advances in high temp superconductors allows magnetic field strengths of up to 12 Tesla. This means the basic physics is in place for a fusion reactor, that could work and produce a good net output. <iframe src='//players.brightcove.net/3058934373001/S1bNWKB9de_default/index.html?videoId=4721014086001' allowfullscreen frameborder=0></iframe> is about the MIT CMAP tokomak. Obviously massive and not ready yet....
Elsewhere antimatter is being produced...
And I have just found Milner and "Starshot to Alpha Centuri" http://earthsky.org/space/breakthrough-starshot-aims-for-alpha-centauri So AN actual mission is being planned.
I hope that since Gwynne has put so much into SX, she will get to see real progress at in this at SX before she retires! A probe will probably get to Alpha Centuri in her lifetime.
Edit: Spelling and bold
« Last Edit: 04/16/2018 11:54 PM by DistantTemple »
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Offline cro-magnon gramps

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Re: TED talk by Gwynne Shotwell
« Reply #38 on: 04/16/2018 05:49 PM »
DistantTemple
Yes I agree ""Working on" doesn't mean "implementing"." And they could already be "working on" Interstellar Propulsion. Now! And GS is rather well placed to know exactly what she's talking about... perhaps that's more obvious today.
I think our minds are quite closed to the future... and the slow pace of space exploration these 50 years has reinforced that. Both Gwynne, and Elon almost have to use tin-openers on our thick heads, to get us to see whats really possible!
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This is something I rail about a lot on the internet, esp. YouTube... the short sightedness of people even when it is right in front of them is astounding... it's like they want to believe in the Easter Bunny more than they do hard science... which may be the problem, science is hard, and many people skip that subject in school, and then society tells them that their "opinion" is just as valid as a scientists observations...

This winter I've been house bound, and spend as much as 8-10 hours a day on youtube... much of it on politics, but again many science based channels... and I'm seeing stuff that is just on the verge of coming out of the lab into production, and other stuff that is portending a future 12 - 15 years out that will blow many peoples minds....

I'll probably get deleted for going OT, but to sum up, I don't believe that Gwynne was just being humours or exaggerating... SpaceX has been in existence for 16 years, and in another 22 years what does anyone think they can accomplish... or for that matter all of Elon's companies in a technological convergence... certainly they will have advanced humanity beyond anything we can imagine today...
« Last Edit: 04/16/2018 05:50 PM by cro-magnon gramps »
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Offline philw1776

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Re: TED talk by Gwynne Shotwell
« Reply #39 on: 04/16/2018 06:24 PM »
SpaceX so far as we know is an engineering firm, not a basic technology R&D firm.
Everything built so far including to-be-built BFR is based on engineering; it's not new R&D like interstellar propulsion would be.  Not even exotic interplanetary propulsion. SpaceX does push and extend the state of the art (engineering) more aggressively than their stolid aerospace competitors or NASA.   Rockets landing on their tails, carbon composite all extensions of what's been done but taken aggressively to another level that the timid eschew.
I see Gwynne's interstellar remark as both a glib throw away and a personal fantasy but known to her, an engineer, as being fantasy.
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Re: TED talk by Gwynne Shotwell
« Reply #40 on: 04/16/2018 06:41 PM »
Why? They certainly don't lack ambition and know that fantasies remain fantasies until someone actually tries to make them reality.
I mean, if their plans succeed they could very well become one of the most valuable companies in the world.
Now they are  forced by their limited budget to be a lot more pragmatic, but in the future nothing would prevent them from establishing very well funded R&D divisions. A bit like Google/Alphabet.
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Offline Jimmy Murdok

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Re: TED talk by Gwynne Shotwell
« Reply #41 on: 04/16/2018 07:02 PM »
Once there is an established industry on orbit and beyond, and if they have tones of cash, working on interstellar capacities is not that out of the scope. Nuclear reactors, advanced electric engines, farms of solar panels, big lasers, big sails... no need of exotic concepts, engineering can start to play

Offline richie2k3

Re: TED talk by Gwynne Shotwell
« Reply #42 on: 04/17/2018 01:37 PM »
Sorry if this is off-topic, but does anbody have a link to the TedTalk? :)
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Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #43 on: 04/17/2018 01:43 PM »
Sorry if this is off-topic, but does anbody have a link to the TedTalk? :)

As mentioned upthread - but it's $25 to access.

Offline richie2k3

Re: TED talk by Gwynne Shotwell
« Reply #44 on: 04/17/2018 02:03 PM »
Sorry if this is off-topic, but does anbody have a link to the TedTalk? :)

As mentioned upthread - but it's $25 to access.

Sorry i missed this :) - are they usally chargable? I thought TED was 'Not for profit' --- for the greater good' etc...

Anyone know the timeframe/likelyhood of this getting on the TED youtube channel?
« Last Edit: 04/17/2018 02:04 PM by richie2k3 »
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Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #45 on: 04/17/2018 02:08 PM »
High, and any time between now and months from now.
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Offline Roy_H

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Re: TED talk by Gwynne Shotwell
« Reply #46 on: 04/17/2018 07:04 PM »
Sorry i missed this :) - are they usally chargable? I thought TED was 'Not for profit' --- for the greater good' etc...
"Not for profit" doesn't mean free. It means lowest possible cost. I am sure they have lots of expenses to cover.
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Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #47 on: 04/17/2018 08:04 PM »
I see Gwynne's interstellar remark as both a glib throw away and a personal fantasy but known to her, an engineer, as being fantasy.

I see it as vision.

Like most things, it will boil down to economics.  Once they're flying thousands of people to Mars on a regular basis, building a massive interstellar ship may not be that much of a stretch.

The problem will be volunteers.  At least initially, you'll need people that are willing to spend their entire life on the ship, and have their offspring be the ones to explore other solar systems.  So the ship will need to be the size of a small city, something like a modern cruise ship, assembled in space.  Something big enough, and with enough other people that it would be comfortable to spend a lifetime there.

After Mars has been settled, I see that as the next big thing.

And with a huge fully reusable launcher, it may not be fantasy.  Remember, BFR will cost less to launch than Falcon 1.

Offline llanitedave

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Re: TED talk by Gwynne Shotwell
« Reply #48 on: 04/17/2018 08:28 PM »
I see Gwynne's interstellar remark as both a glib throw away and a personal fantasy but known to her, an engineer, as being fantasy.

I see it as vision.

Like most things, it will boil down to economics.  Once they're flying thousands of people to Mars on a regular basis, building a massive interstellar ship may not be that much of a stretch.

The problem will be volunteers.  At least initially, you'll need people that are willing to spend their entire life on the ship, and have their offspring be the ones to explore other solar systems.  So the ship will need to be the size of a small city, something like a modern cruise ship, assembled in space.  Something big enough, and with enough other people that it would be comfortable to spend a lifetime there.

After Mars has been settled, I see that as the next big thing.

And with a huge fully reusable launcher, it may not be fantasy.  Remember, BFR will cost less to launch than Falcon 1.


Only if it comes back.  If it's heading out into the void, it'll be nice and pricey.
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Offline Roy_H

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Re: TED talk by Gwynne Shotwell
« Reply #49 on: 04/17/2018 09:15 PM »
I see Gwynne's interstellar remark as both a glib throw away and a personal fantasy but known to her, an engineer, as being fantasy.

I see it as vision.

Like most things, it will boil down to economics.  Once they're flying thousands of people to Mars on a regular basis, building a massive interstellar ship may not be that much of a stretch.

The problem will be volunteers.  At least initially, you'll need people that are willing to spend their entire life on the ship, and have their offspring be the ones to explore other solar systems.  So the ship will need to be the size of a small city, something like a modern cruise ship, assembled in space.  Something big enough, and with enough other people that it would be comfortable to spend a lifetime there.

After Mars has been settled, I see that as the next big thing.

And with a huge fully reusable launcher, it may not be fantasy.  Remember, BFR will cost less to launch than Falcon 1.

I think human interstellar travel is a long way off. I imagine Shotwell was talking about a probe.
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Offline Jimmy Murdok

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Re: TED talk by Gwynne Shotwell
« Reply #50 on: 04/17/2018 09:49 PM »
"Not for profit" doesn't mean free. It means lowest possible cost. I am sure they have lots of expenses to cover.
In the era of Netflix flat rates, I find 25$ a bit elitist for a video of a non profit that quotes ďIdeas worth spreadingĒ. Who knows maybe Gwyne is so expensive to bring, but I understand is part of her job.
« Last Edit: 04/17/2018 09:53 PM by Jimmy Murdok »

Offline clongton

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Re: TED talk by Gwynne Shotwell
« Reply #51 on: 04/17/2018 10:06 PM »
Sorry i missed this :) - are they usally chargable? I thought TED was 'Not for profit' --- for the greater good' etc...
"Not for profit" doesn't mean free. It means lowest possible cost. I am sure they have lots of expenses to cover.

I have never had to pay to watch a TED talk - ever. Is this new?
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Offline tater

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Re: TED talk by Gwynne Shotwell
« Reply #52 on: 04/17/2018 10:12 PM »
It might be that it airs free after some time period, and people desperate to watch earlier have to pay. Think of it like L2. Stuff there right away, but eventually it makes it out.

Offline ClayJar

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Re: TED talk by Gwynne Shotwell
« Reply #53 on: 04/17/2018 11:16 PM »
I have never had to pay to watch a TED talk - ever. Is this new?

It's relatively new, but it's in addition to the free option.  As I recall, I used to see the option to pay for the full live streaming package (and decline to do so due to price), but after that, there was no option but to wait for the TED Talks to show up for free streaming at an indeterminate point in the future.  The intermediate step of having a less expensive paid option for non-live but basically immediate streaming just adds an additional option.

Personally, I'm content to wait until I can watch it free, but it is just a bit more tempting at $25 for the session than it was at full price for the whole thing.

Online nacnud

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Re: TED talk by Gwynne Shotwell
« Reply #54 on: 04/17/2018 11:24 PM »
I did a google (yes google is a verb now however much they defend the trademark)

https://www.ted.com/about/our-organization/how-ted-works

Quote
How does TED make money?

TED makes money through conference attendance fees, sponsorships, foundation support, licensing fees and book sales, and we spend it as soon as we get it ó on video editing, web development and hosting for TED Talks and TED-Ed videos (ideas are free, but bandwidth is expensiveÖ); support for community-driven initiatives like TEDx and the TED Fellows, and of course, paying fair salaries to staffers and interns.

Everyone who buys a pass to attend a TED conference is helping share free TED Talks video with the world, as well as supporting the TEDx program, the TED Prize, free TED Fellowships, TED-Ed video lessons and more great stuff that is shared with the world for free. For this reason, a percentage of the attendance fee is a charitable contribution.

TED Talks on the web are also supported by partnerships with carefully selected organizations; their ads on the videos and website support making TED Talks available to the world for free in many languages and on many platforms. We are very selective in the organizations we partner with. Other projects and initiatives are supported by foundation funding and individual donors.

And of course we're also supported in kind by tens of thousands of volunteers ó like all the amazing translators with the Open Translation Project, TEDx organizers, TED.com conversation moderators, organizations and individuals that support the TED Prize, and everyone who ever shares a TED Talk with someone else. (Thank you!)

So will it be free soon? Best answer is, maybe.

Offline JamesH65

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Re: TED talk by Gwynne Shotwell
« Reply #55 on: 04/18/2018 11:52 AM »
SpaceX so far as we know is an engineering firm, not a basic technology R&D firm.

If SpaceX don't have a skunkworks R&D/investigative team somewhere I would be very very surprised.

Offline Proponent

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Re: TED talk by Gwynne Shotwell
« Reply #56 on: 04/18/2018 11:59 AM »
Sorry i missed this :) - are they usally chargable? I thought TED was 'Not for profit' --- for the greater good' etc...
"Not for profit" doesn't mean free. It means lowest possible cost. I am sure they have lots of expenses to cover.

As  I understand it, the key thing about a non-profit organization is that any profits generated go to promoting a cause.  A non-profit can still charge (high) fees, make big profits, and pay its staff well.  The designation is effectively more about the ownership of the organization than how it operates.
« Last Edit: 04/18/2018 12:00 PM by Proponent »

Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #57 on: 04/18/2018 12:17 PM »
And with a huge fully reusable launcher, it may not be fantasy.  Remember, BFR will cost less to launch than Falcon 1.
Only if it comes back.  If it's heading out into the void, it'll be nice and pricey.
Unless you've invented a magic drive that can take a BFS to the stars from LEO, BFS once you get about 10km/s from earth isn't what you want to use, and even very cheap solutions dramatically outperform it.
Getting BFS back is cheap, with perhaps the exception of if you're going to try a large gravity well manoever right next to jupiter.

Any semi-plausible interstellar precursor mission is not going to be dragging along 85 tons of dead weight.

For example, assuming BFS is $100M and launch cost to spacex is $10/kg as implied by P2P.
With $100M, you can launch ten thousand tons of simple balloon tanks and engines capable of throwing 2 tons to 30km/s.


« Last Edit: 04/18/2018 12:23 PM by speedevil »

Offline su27k

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Re: TED talk by Gwynne Shotwell
« Reply #58 on: 04/18/2018 01:07 PM »
SpaceX so far as we know is an engineering firm, not a basic technology R&D firm.
Everything built so far including to-be-built BFR is based on engineering; it's not new R&D like interstellar propulsion would be.  Not even exotic interplanetary propulsion. SpaceX does push and extend the state of the art (engineering) more aggressively than their stolid aerospace competitors or NASA.   Rockets landing on their tails, carbon composite all extensions of what's been done but taken aggressively to another level that the timid eschew.
I see Gwynne's interstellar remark as both a glib throw away and a personal fantasy but known to her, an engineer, as being fantasy.

NASA is funding various exotic propulsion concepts, hopefully in 20 years some of them would be mature enough to be picked up by SpaceX TNG. By then I would hope we'll have a Mars base already, and the interstellar propulsion can be worked on as a faster Mars cargo delivery system, just like right now the Mars vehicle is being worked on as a big satellite launcher.

Offline llanitedave

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Re: TED talk by Gwynne Shotwell
« Reply #59 on: 04/18/2018 09:44 PM »
And with a huge fully reusable launcher, it may not be fantasy.  Remember, BFR will cost less to launch than Falcon 1.
Only if it comes back.  If it's heading out into the void, it'll be nice and pricey.
Unless you've invented a magic drive that can take a BFS to the stars from LEO, BFS once you get about 10km/s from earth isn't what you want to use, and even very cheap solutions dramatically outperform it.
Getting BFS back is cheap, with perhaps the exception of if you're going to try a large gravity well manoever right next to jupiter.

Any semi-plausible interstellar precursor mission is not going to be dragging along 85 tons of dead weight.

For example, assuming BFS is $100M and launch cost to spacex is $10/kg as implied by P2P.
With $100M, you can launch ten thousand tons of simple balloon tanks and engines capable of throwing 2 tons to 30km/s.


SpaceX showed pictures of BFS's landed in exotic locations like asteroids or Jupiter's moons.  Those would be very hard to get back.  If they fueled in Mars orbit, they could send a probe with another propulsion module off to a much faster trip outbound, but we're still talking about a trip beyond its designed capabilities.
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Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #60 on: 04/19/2018 12:11 AM »
And with a huge fully reusable launcher, it may not be fantasy.  Remember, BFR will cost less to launch than Falcon 1.
Only if it comes back.  If it's heading out into the void, it'll be nice and pricey.
Unless you've invented a magic drive that can take a BFS to the stars from LEO, BFS once you get about 10km/s from earth isn't what you want to use, and even very cheap solutions dramatically outperform it.

I think BFS is way too small for interstellar travel.  I'm talking about something that can carry thousands of passengers, with artificial gravity, and with enough space to manufacture some things on board.  Basically a small city. Something people could live on for decades.

Remember, once BFR is flying regularly, cost per BFR launch will be less than Falcon 1, i.e. less than $7 million per BFR launch, and each launch will get 150 tons to LEO.

So for example, if it took 50 BFR launches to get the interstellar ship and propellant into LEO, total launch costs would be $350 million.

As I said before, it all boils down to economics, and BFR is a total game-changer here.

So when Gwynne talks about interstellar travel, I suspect shes thinking how it may work economically using BFR.

Online DistantTemple

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Re: TED talk by Gwynne Shotwell
« Reply #61 on: 04/19/2018 01:04 AM »
And with a huge fully reusable launcher, it may not be fantasy.  Remember, BFR will cost less to launch than Falcon 1.
Only if it comes back.  If it's heading out into the void, it'll be nice and pricey.
Unless you've invented a magic drive that can take a BFS to the stars from LEO, BFS once you get about 10km/s from earth isn't what you want to use, and even very cheap solutions dramatically outperform it.

I think BFS is way too small for interstellar travel.  I'm talking about something that can carry thousands of passengers, with artificial gravity, and with enough space to manufacture some things on board.  Basically a small city. Something people could live on for decades.

Remember, once BFR is flying regularly, cost per BFR launch will be less than Falcon 1, i.e. less than $7 million per BFR launch, and each launch will get 150 tons to LEO.

So for example, if it took 50 BFR launches to get the interstellar ship and propellant into LEO, total launch costs would be $350 million.

As I said before, it all boils down to economics, and BFR is a total game-changer here.

So when Gwynne talks about interstellar travel, I suspect shes thinking how it may work economically using BFR.
I believe she's serious, not joking... but BFR is not the ship for it. Unmanned probes would be first, and in 10 or 15 years the company "Planetary Resources" will be beginning to mine asteroids, the first production of steel on Mars will be underway, and Space Exploration technologies Corporation, a $200Bn enterprise will be working out how to mass produce tokomak fusion reactors light enough to put in ships.

Its one thing journeying for a couple of years in space... but if its a twenty year journey, either it will be a ship like a city, with careers.. children ... a mobile space city, or most crew will be in hibernation. And any large ship will be built in orbit, with the main Mass becoming less likely to come from Earth. In my opinion...
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Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #62 on: 04/19/2018 02:10 AM »
Gwynne didn't say BFS would be for actual interstellar travel.

But I think BFS is about the right size. You'd want the crew hibernating for the vast majority of the time, even for, say, 80% c travel (although 10% c is FAR more realistic). That makes it orders of magnitude easier to build.
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Offline niwax

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Re: TED talk by Gwynne Shotwell
« Reply #63 on: 04/19/2018 08:39 AM »
And with a huge fully reusable launcher, it may not be fantasy.  Remember, BFR will cost less to launch than Falcon 1.
Only if it comes back.  If it's heading out into the void, it'll be nice and pricey.
Unless you've invented a magic drive that can take a BFS to the stars from LEO, BFS once you get about 10km/s from earth isn't what you want to use, and even very cheap solutions dramatically outperform it.

I think BFS is way too small for interstellar travel.  I'm talking about something that can carry thousands of passengers, with artificial gravity, and with enough space to manufacture some things on board.  Basically a small city. Something people could live on for decades.

Remember, once BFR is flying regularly, cost per BFR launch will be less than Falcon 1, i.e. less than $7 million per BFR launch, and each launch will get 150 tons to LEO.

So for example, if it took 50 BFR launches to get the interstellar ship and propellant into LEO, total launch costs would be $350 million.

As I said before, it all boils down to economics, and BFR is a total game-changer here.

So when Gwynne talks about interstellar travel, I suspect shes thinking how it may work economically using BFR.
I believe she's serious, not joking... but BFR is not the ship for it. Unmanned probes would be first, and in 10 or 15 years the company "Planetary Resources" will be beginning to mine asteroids, the first production of steel on Mars will be underway, and Space Exploration technologies Corporation, a $200Bn enterprise will be working out how to mass produce tokomak fusion reactors light enough to put in ships.

Its one thing journeying for a couple of years in space... but if its a twenty year journey, either it will be a ship like a city, with careers.. children ... a mobile space city, or most crew will be in hibernation. And any large ship will be built in orbit, with the main Mass becoming less likely to come from Earth. In my opinion...

BFR isn't the ship but Mars ist likely the origin. A full BFR stack can throw something like 400t to orbit on Mars, making big habitation modules so much easier.

Offline Hominans Kosmos

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Re: TED talk by Gwynne Shotwell
« Reply #64 on: 04/19/2018 08:56 AM »
Gwynne didn't say BFS would be for actual interstellar travel.

But I think BFS is about the right size. You'd want the crew hibernating for the vast majority of the time, even for, say, 80% c travel (although 10% c is FAR more realistic). That makes it orders of magnitude easier to build.

BFS would not be large enough for the radiation shielding required to travel at 80%c

It also has perhaps enough room for supplies for one mouse. Not nearly big enough for human interstellar voyages.

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Re: TED talk by Gwynne Shotwell
« Reply #65 on: 04/19/2018 10:58 AM »
We are quickly leaving the realm of sensible engineering here. Interstellar travel is outside our current and foreseeable future engineering capabilities. Despite everyone disagreeing with my initial statement, this pretty much proves it's validity.

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #66 on: 04/19/2018 11:00 AM »
You'd want the crew hibernating for the vast majority of the time, even for, say, 80% c travel (although 10% c is FAR more realistic).

Yes, 0.1c is far more realistic, at least initially. This means interstellar travel will take decades.

I don't think we yet have hibernation technology that works for decades.  As an alternative, if we make the interstellar ship like a small city, some people wouldn't mind living there.

As an analogy, BFR/BFS trips to Mars will mostly be 1-way.  The BFS return payload capability is a small fraction of the payload capability to Mars.  So some dissatisfied Mars colonists could return, but the majority would just stay on Mars and live the rest of their lives there.

Similarly, for interstellar travel, I think it will be more like a traveling colony, where the people that make that journey have no expectation of coming back to Earth.  If there's 3000-5000 other passengers, artificial gravity, and ample space on board for small manufacturing and other things, life on board may be pretty good.

With traditional rockets, such a huge ship is science-fiction. But with BFR/BFS launch costs less than Falcon 1, that works out to around $20/pound to LEO.  At that price, many things that were science-fiction may become reality. 

I think this is what Gwynne was referring to at TED.

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #67 on: 04/19/2018 11:03 AM »
We are quickly leaving the realm of sensible engineering here. Interstellar travel is outside our current and foreseeable future engineering capabilities.
Why?

What technology do we lack to do what I described above?

With traditional launch costs, yes, it wouldn't be sensible economically, but BFR changes that.

Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #68 on: 04/19/2018 11:14 AM »
We are quickly leaving the realm of sensible engineering here. Interstellar travel is outside our current and foreseeable future engineering capabilities.
Why?

What technology do we lack to do what I described above?

With traditional launch costs, yes, it wouldn't be sensible economically, but BFR changes that.
No, it really, really, really doesn't.
BFR is entirely irrelevant to vehicles going at 0.1c, as it adds nothing over the vehicle just starting in LEO.
BFR can just about - with an insane amount of effort recoverably hit 20km/s. ( around a thousand tanker launches)

20km/s is 0.007% of the speed of light, not 10%.

In order to get BFS in LEO to 10% of the speed of light, starting out at 1185 tons, and burning to 85 tons, the engines would need an ISP of 1.1 million seconds.

If we imagine it is accellerating at 1m/s for one year, the initial required power is 10^14W.

Or put in perhaps more familiar units, a hundred kiloton nuclear weapon, every second, for a year.

(edit: had energy seven orders of magnitude too high)
« Last Edit: 04/19/2018 03:55 PM by speedevil »

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #69 on: 04/19/2018 11:20 AM »
BFR is entirely irrelevant to vehicles going at 0.1c, as it adds nothing over the vehicle just starting in LEO.
BFR can just about - with an insane amount of effort recoverably hit 20km/s. ( around a thousand tanker launches)

You're not hearing me.  I'm not talking about using BFR for interstellar travel. 

I'm talking about BFR launch costs enabling interstellar travel.  A BFR launch will only cost around $7 million, an each launch will get 150 tons to LEO.  That works out to around $20/pound.

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Re: TED talk by Gwynne Shotwell
« Reply #70 on: 04/19/2018 11:32 AM »
I don't think there will be hibernation technology, period. At least not for adults. The body is just too fragile and susceptible to damage. However it is possible to freeze embryos for extended periods. It is also possible to assemble life forms from mail order parts, and was done over 15 years ago.

If you think artificial wombs or life assembled from component parts are far fetched then the autonomous machines needed to build the infrastructure at the other end of any interstellar journey is a much bigger challenge.

Remember the payload of any reasonable interstellar craft is in the orders of grams to kilograms and journey times of decades.

This sounds very off topic but if you look at the other areas Elon is working on, AI, brain-machine interfaces, autonomous cars, and combine it with the reduction in launch costs then a lot of the long poles for a starwisp type mission are being actively worked on.

Propulsion is perhaps the last step and I guess that will have to wait until whatever follows BFR when SpaceX starts getting serious about nuclear power either as an energy source for a reaction engine or to power the lasers for a starwisp type craft.
« Last Edit: 04/19/2018 11:36 AM by nacnud »

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Re: TED talk by Gwynne Shotwell
« Reply #71 on: 04/19/2018 11:36 AM »
You're not hearing me.  I'm not talking about using BFR for interstellar travel. 

I'm talking about BFR launch costs enabling interstellar travel.  A BFR launch will only cost around $7 million, an each launch will get 150 tons to LEO.  That works out to around $20/pound.
The problem is that if you assume interstellar travel is plausible, most of the technologies involved are so far down the line, and have such large possibilities that they make at the very least BFR pricing entirely utterly irrelevant.
It's essentially precisely the same as arguing that a cheaper mule wagon makes supersonic transport plausible.
There is no meaningful difference between $100000/lb and $10/lb launch costs for interstellar travel with BFS, because it's simply not happening in the same time.

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Re: TED talk by Gwynne Shotwell
« Reply #72 on: 04/19/2018 11:51 AM »
Calculate the costs to launch a 10,000 tonne starwisp laser via falcon 9 or BFR

It is probably within the budget of nation states if launched via BFR but not if launched via F9. (I'm thinking in the terms of ISS total budget)

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Re: TED talk by Gwynne Shotwell
« Reply #73 on: 04/19/2018 11:54 AM »
You're not hearing me.  I'm not talking about using BFR for interstellar travel. 

I'm talking about BFR launch costs enabling interstellar travel.  A BFR launch will only cost around $7 million, an each launch will get 150 tons to LEO.  That works out to around $20/pound.
The problem is that if you assume interstellar travel is plausible, most of the technologies involved are so far down the line, and have such large possibilities that they make at the very least BFR pricing entirely utterly irrelevant.
It's essentially precisely the same as arguing that a cheaper mule wagon makes supersonic transport plausible.
There is no meaningful difference between $100000/lb and $10/lb launch costs for interstellar travel with BFS, because it's simply not happening in the same time.

It's no accident that after working on Daedalus in the late seventies, a design for an Interstellar fusion starship, Alan Bond and his colleagues went on to develop Skylon.  They realized that cheap access to space is essential for the development of a space economy, that is a pre-requisite for Interstellar travel (except perhaps for project Starshot and its mini flyby vehicles).
A 1000x reduction in cost is more than a better mule train.  It's at least a steam shovel :-), perhaps even a bulldozer.

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Re: TED talk by Gwynne Shotwell
« Reply #74 on: 04/19/2018 12:27 PM »
Gwynne didn't say BFS would be for actual interstellar travel.

But I think BFS is about the right size. You'd want the crew hibernating for the vast majority of the time, even for, say, 80% c travel (although 10% c is FAR more realistic). That makes it orders of magnitude easier to build.
Better yet, send just the frozen head and grow a new body at the destination, with local resources.

Still better, send a silicon copy that does not need life support and is happy to live in a low temperature vacuum.

This kind of reduce-the-payload-mass engineering is (IMO, obviously) more enabling than improve-the-rocket engineering.   Both will be required, but it makes little sense to design a star ship that will take many decades to get there, while the biology and computation that could dramatically reduce your payload is changing enormously on single-decade timescales.


Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #75 on: 04/19/2018 01:08 PM »
Gwynne didn't say BFS would be for actual interstellar travel.

But I think BFS is about the right size. You'd want the crew hibernating for the vast majority of the time, even for, say, 80% c travel (although 10% c is FAR more realistic). That makes it orders of magnitude easier to build.

BFS would not be large enough for the radiation shielding required to travel at 80%c

It also has perhaps enough room for supplies for one mouse. Not nearly big enough for human interstellar voyages.
If itís closed loop including for calories, then itís big enough. Also, I was referring to crew volume size, not the size of the whole spaceship. The spaceship will likely need to be hundreds of kilometers wide, of you include superconducting magnetic coils for braking (etc) and possibly magnetic shielding as well. I wasnít necessarily including the Whipple shield in that, either.
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Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #76 on: 04/19/2018 01:11 PM »
Gwynne didn't say BFS would be for actual interstellar travel.

But I think BFS is about the right size. You'd want the crew hibernating for the vast majority of the time, even for, say, 80% c travel (although 10% c is FAR more realistic). That makes it orders of magnitude easier to build.
Better yet, send just the frozen head and grow a new body at the destination, with local resources.

Still better, send a silicon copy that does not need life support and is happy to live in a low temperature vacuum.

This kind of reduce-the-payload-mass engineering is (IMO, obviously) more enabling than improve-the-rocket engineering.   Both will be required, but it makes little sense to design a star ship that will take many decades to get there, while the biology and computation that could dramatically reduce your payload is changing enormously on single-decade timescales.
I think itís an exaggeration to say biology has changed a lot in a decade. Computation growth rate is also slowing down on the hardware side due to the end of Mooreís Law. I guess General AI is a wild card, there, but itís not actually predictable by its very nature.

Once you get to about 10% c, diminishing returns, IMO.
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Re: TED talk by Gwynne Shotwell
« Reply #77 on: 04/19/2018 02:10 PM »
This kind of reduce-the-payload-mass engineering is (IMO, obviously) more enabling than improve-the-rocket engineering.   Both will be required, but it makes little sense to design a star ship that will take many decades to get there, while the biology and computation that could dramatically reduce your payload is changing enormously on single-decade timescales.
I think itís an exaggeration to say biology has changed a lot in a decade.
This statement makes me pretty sure you are not a biologist.  Whole new techniques are being discovered almost daily.  Gene editing techniques such as CRISPR/CAS9 makes the headlines, but there are many, many others.  And biological engineering today is like chip design in the 1970s.- there are huge advances to be made that are conceptually clear, but for which the required technology does not quite exist.

Take even a quick look at eLife or Frontiers in Neuroscience, and you will see a field that's changing at a boggling pace.

Offline Johnnyhinbos

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Re: TED talk by Gwynne Shotwell
« Reply #78 on: 04/19/2018 02:35 PM »
aaaaaand... Gwynne has left the building...
John Hanzl. Author, action / adventure www.johnhanzl.com

Offline john smith 19

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Re: TED talk by Gwynne Shotwell
« Reply #79 on: 04/19/2018 03:08 PM »
No, it really, really, really doesn't.
BFR is entirely irrelevant to vehicles going at 0.1c, as it adds nothing over the vehicle just starting in LEO.
BFR can just about - with an insane amount of effort recoverably hit 20km/s. ( around a thousand tanker launches)

20km/s is 0.007% of the speed of light, not 10%.

In order to get BFS in LEO to 10% of the speed of light, starting out at 1185 tons, and burning to 85 tons, the engines would need an ISP of 1.1 million seconds.

If we imagine it is accellerating at 1m/s for one year, the initial required power is 10^20W.

Or put in perhaps more familiar units, a little more than a hundred times the total energy release of all nuclear weapons ever detonated, every second, for a year.
The fission fragment rocket (basically a nuclear reactor where the fission products are directed out the back) is estimated to be capable of an Isp of 1 000 000secs. Fission products around 5-7% of C.

Not easy to engineer, and the thrust is estimated to be in the Newton range (pretty good for most of these high Isp concepts) but it does not require any breakthroughs in theory.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #80 on: 04/19/2018 03:52 PM »
The fission fragment rocket (basically a nuclear reactor where the fission products are directed out the back) is estimated to be capable of an Isp of 1 000 000secs. Fission products around 5-7% of C.

Not easy to engineer, and the thrust is estimated to be in the Newton range (pretty good for most of these high Isp concepts) but it does not require any breakthroughs in theory.

FFR is great for missions to Eris, unfortunately, the power density is quite small, meaning it accelerates very slowly and can push a comparably minimal amount of mass, and burnout happens quite early as the reactor runs out of energy.
A million second-newton is a 20MW or so reactor.

Offline chipguy

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Re: TED talk by Gwynne Shotwell
« Reply #81 on: 04/19/2018 05:18 PM »
And biological engineering today is like chip design in the 1970s.- there are huge advances to be made that are conceptually clear, but for which the required technology does not quite exist.

Totally agree. I have ridden the incredible semiconductor wave for over 30 years but the signs
of plateauing are clearly there.

I encouraged my daughters to go into bio engineering of all the sciences because that is what
seems will dominate massive technological change over the next 30 years.

Beyond engines, mass fractions, and nuclear propulsion - the biggest problem is that man is
*currently* entirely unsuited for space in countless ways. Improving the payload goes a long
way in making the delivery vehicle more practical. This is true for colonising the solar system
and likely far more important for thinking of pushing beyond.

Offline Semmel

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Re: TED talk by Gwynne Shotwell
« Reply #82 on: 04/19/2018 06:46 PM »
It seems, in the absence of evidence, forum threads diverge into off-topicness. Maybe we should stop here and wait for the video to become public before continuing. There is no point in discussing this any further. If you want to discuss interstellar travel, there is a nice forum section called "Advanced Concepts" or if you feel really adventurous "New Physics for Space Technology". Please stop.

Offline deruch

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Re: TED talk by Gwynne Shotwell
« Reply #83 on: 04/19/2018 08:14 PM »
And biological engineering today is like chip design in the 1970s.- there are huge advances to be made that are conceptually clear, but for which the required technology does not quite exist.

Totally agree. I have ridden the incredible semiconductor wave for over 30 years but the signs
of plateauing are clearly there.

I encouraged my daughters to go into bio engineering of all the sciences because that is what
seems will dominate massive technological change over the next 30 years.

Beyond engines, mass fractions, and nuclear propulsion - the biggest problem is that man is
*currently* entirely unsuited for space in countless ways. Improving the payload goes a long
way in making the delivery vehicle more practical. This is true for colonising the solar system
and likely far more important for thinking of pushing beyond.

Just one word: Plastics.
Shouldn't reality posts be in "Advanced concepts"?  --Nomadd

Offline john smith 19

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Re: TED talk by Gwynne Shotwell
« Reply #84 on: 04/20/2018 07:08 AM »

Totally agree. I have ridden the incredible semiconductor wave for over 30 years but the signs
of plateauing are clearly there.
It's been very amusing to watch people talking about "Extreme UV" when they just can't even bring themselves to say "Soft X-ray."

When you're at the point when line widths are better quoted in the number of atoms wide they are you know things are coming to a limit.

I don't think some of those MBA types are going to like being told "We are 10 atoms wide for the conductor and 1 atom thick for the gate insulator,  we can't go any smaller." I imagine at leas a few of them will be saying "Well, make the atoms smaller."

However this is OT for this thread.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

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Re: TED talk by Gwynne Shotwell
« Reply #85 on: 04/20/2018 07:19 AM »
FFR is great for missions to Eris, unfortunately, the power density is quite small, meaning it accelerates very slowly and can push a comparably minimal amount of mass, and burnout happens quite early as the reactor runs out of energy.
A million second-newton is a 20MW or so reactor.
I'd point out that typical NTR reactors were in the GW power range in the early 1970's.

I'd also note that for an Isp of 1000 000 you get a mass ratio of about 21 for 10% of C and once outside of a planetary gravity well its thrust is not that important. It will take a long while to accelerate to cruise speed.

Most importantly there has been very little serious effort on engineering a FFR.  I was merely pointing out no new physics are needed to do it, but the engineering is complex.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Hick2

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Re: TED talk by Gwynne Shotwell
« Reply #86 on: 04/20/2018 03:25 PM »
Apparently the TED Video is being posted on Monday (Reddit Source)

Offline ThePonjaX

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Re: TED talk by Gwynne Shotwell
« Reply #87 on: 04/20/2018 10:44 PM »
In the comments on that post on reddit some user point to a rumor about joint between NASA and Spacex:

" He'll be fine as none of our missions are expected to be cut or restructured, we have two huge reveals next year too along with a joint phase with SpaceX. "

Source:
https://np.reddit.com/r/space/comments/8dh1xv/jim_bridenstine_confirmed_as_new_director_of_nasa/dxnp9o3/

If this is true this is very interesting.

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #88 on: 04/21/2018 12:07 AM »
You're not hearing me.  I'm not talking about using BFR for interstellar travel. 

I'm talking about BFR launch costs enabling interstellar travel.  A BFR launch will only cost around $7 million, an each launch will get 150 tons to LEO.  That works out to around $20/pound.
The problem is that if you assume interstellar travel is plausible, most of the technologies involved are so far down the line...

NTR has been around since the 60's.  Same with Nuclear pulse propulsion.

The main issue until now has been launch costs.

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #89 on: 04/21/2018 12:11 AM »
It seems, in the absence of evidence, forum threads diverge into off-topicness. Maybe we should stop here and wait for the video to become public before continuing. There is no point in discussing this any further. If you want to discuss interstellar travel...

We know for a fact that Gwynne talked about interstellar at TED.

On topic.

Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #90 on: 04/21/2018 02:17 AM »
This kind of reduce-the-payload-mass engineering is (IMO, obviously) more enabling than improve-the-rocket engineering.   Both will be required, but it makes little sense to design a star ship that will take many decades to get there, while the biology and computation that could dramatically reduce your payload is changing enormously on single-decade timescales.
I think itís an exaggeration to say biology has changed a lot in a decade.
This statement makes me pretty sure you are not a biologist.  Whole new techniques are being discovered almost daily.  Gene editing techniques such as CRISPR/CAS9 makes the headlines, but there are many, many others.  And biological engineering today is like chip design in the 1970s.- there are huge advances to be made that are conceptually clear, but for which the required technology does not quite exist.

Take even a quick look at eLife or Frontiers in Neuroscience, and you will see a field that's changing at a boggling pace.
My bad for miscommunication. Iím not a biologist. Yet I am aware of these changes (and indeed, many are incredibly exciting), but few are relevant to interstellar travel in a way that couldnít be sent to the ship while in transit. And anyway that wasnít my point.

Maybe I misunderstood the point the original poster was making about biology, but my point was this: we humans still havenít changed much biologically in the last few decades. But computers HAVE changed by orders of magnitude in the same timeframe. My point was about humansí biology.
« Last Edit: 04/21/2018 02:19 AM by Robotbeat »
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Re: TED talk by Gwynne Shotwell
« Reply #91 on: 04/21/2018 06:16 PM »
In the comments on that post on reddit some user point to a rumor about joint between NASA and Spacex:

" He'll be fine as none of our missions are expected to be cut or restructured, we have two huge reveals next year too along with a joint phase with SpaceX."

Source:
https://np.reddit.com/r/space/comments/8dh1xv/jim_bridenstine_confirmed_as_new_director_of_nasa/dxnp9o3/

If this is true this is very interesting.

CCP crewed flight next year. Nothing new. Been in the making for years.

Offline ChrisWilson68

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Re: TED talk by Gwynne Shotwell
« Reply #92 on: 04/22/2018 12:48 AM »
SpaceX so far as we know is an engineering firm, not a basic technology R&D firm.

That is an artificial distinction if I've ever seen one!

Some people seem to have forgotten we've already launched interstellar objects -- decades ago.  The Voyager probes will take many thousands of years to get to another star system, and they won't be functioning when they do, but the point is that there's no magic to launching something to another star system.  We can already do it.  It's just a matter of improving the state of the art until it reaches the point we can do practical things with it.

Which is exactly what SpaceX has a history of doing.

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Acronyms are the enemy of understanding. Why not spell them out and let everyone understand what you are saying?

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Re: TED talk by Gwynne Shotwell
« Reply #94 on: 04/23/2018 05:48 PM »
Talk is now up on their website:

https://www.ted.com/talks/gwynne_shotwell_spacex_s_plan_to_fly_you_across_the_globe_in_30_minutes?utm_campaign=tedspread&utm_medium=referral&utm_source=tedcomshare

Watched it. Most interesting bit to me was explicit discussion of "Elon time" vs. "Gwynne time" (which is more like when things actually happen in the real world) -- she acknowledged that the difference is typically a factor of two. But went on to say that point-to-point BFR flights will happen within ten years -- Gwen time. Also noted that Elon likes to shake things up, and said her job got a whole lot easier when she started thinking of it (in effect) as getting the company in the best possible shape for the next disruption.

Aside from that, not much new to this audience; no new technical details.
« Last Edit: 04/23/2018 08:08 PM by rst »

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Re: TED talk by Gwynne Shotwell
« Reply #95 on: 04/23/2018 05:57 PM »
Talk is now up on their website:

https://www.ted.com/talks/gwynne_shotwell_spacex_s_plan_to_fly_you_across_the_globe_in_30_minutes?utm_campaign=tedspread&utm_medium=referral&utm_source=tedcomshare

Watched it. Most interesting bit to me was explicit discussion of "Elon time" vs. "Gwen time" (which is more like when things actually happen in the real world) -- she acknowledged that the difference is typically a factor of two. But went on to say that point-to-point BFR flights will happen within ten years -- Gwen time. Also noted that Elon likes to shake things up, and said her job got a whole lot easier when she started thinking of it (in effect) as getting the company in the best possible shape for the next disruption.

Aside from that, not much new to this audience; no new technical details.

She did let slip they are going to build a bigger BFR and try to reduce Mars transfer time

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Re: TED talk by Gwynne Shotwell
« Reply #96 on: 04/23/2018 05:58 PM »
Talk is now up on their website:

https://www.ted.com/talks/gwynne_shotwell_spacex_s_plan_to_fly_you_across_the_globe_in_30_minutes?utm_campaign=tedspread&utm_medium=referral&utm_source=tedcomshare

Watched it. Most interesting bit to me was explicit discussion of "Elon time" vs. "Gwen time" (which is more like when things actually happen in the real world) -- she acknowledged that the difference is typically a factor of two. But went on to say that point-to-point BFR flights will happen within ten years -- Gwen time. Also noted that Elon likes to shake things up, and said her job got a whole lot easier when she started thinking of it (in effect) as getting the company in the best possible shape for the next disruption.

Aside from that, not much new to this audience; no new technical details.
Better image quality did make it clear that the "new" BFS still has 2 engines.

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Re: TED talk by Gwynne Shotwell
« Reply #97 on: 04/23/2018 07:02 PM »
She did let slip they are going to build a bigger BFR and try to reduce Mars transfer time

That has been known since the ITS reveal in 2016.

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Re: TED talk by Gwynne Shotwell
« Reply #98 on: 04/23/2018 07:22 PM »
She did let slip they are going to build a bigger BFR and try to reduce Mars transfer time

That has been known since the ITS reveal in 2016.
As this has ebbed and flowed, its good to hear it from GS again.... And it didn't sound like many years in the future!
We can always grow new new dendrites. Reach out and make connections and your world will burst with new insights. Then repose in consciousness.

Offline IainMcClatchie

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Re: TED talk by Gwynne Shotwell
« Reply #99 on: 04/23/2018 09:18 PM »
Iím not a biologist. Yet I am aware of these changes (and indeed, many are incredibly exciting), but few are relevant to interstellar travel in a way that couldnít be sent to the ship while in transit.

Wow.  Never thought of that before.

You are sort of suggesting that, once we've got the ability to "3D print" lab equipment and so forth that would be sufficient to assemble a human being from raw materials, that we just build a probe loaded with that "3D printer" and raw materials, and fire that on a 1000-year journey to various stars.

While it's on the way, we'll develop the technology for whatever we'll want to have when it gets there, and then send it the plans.  If we want to have people out there to explore the new system, it'll print those too.

I'd never thought of that before.  Seems like an interesting Sci Fi story concept.  The protagonist wakes up in a probe ship 10 lifetimes' journey from the nearest other person....

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #100 on: 04/23/2018 09:47 PM »
Watched it. Most interesting bit to me was explicit discussion of "Elon time" vs. "Gwynne time" (which is more like when things actually happen in the real world) -- she acknowledged that the difference is typically a factor of two.

I also watched it, but I didn't get the sense that she acknowledged anything specific about the the difference between "Elon time" vs. "Gwynne time".  The interviewer suggested it may be a factor of two, and she just acknowledged that's what he said, and added that his guess was "not terrible".

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #101 on: 04/23/2018 09:52 PM »
Better image quality did make it clear that the "new" BFS still has 2 engines.
I believe that's the same video from last September.

Since then, Elon said said it will have 3 engines. Specifically:
https://www.reddit.com/r/space/comments/76e79c/i_am_elon_musk_ask_me_anything_about_bfr/
Quote
In order to be able to land the BF Ship with an engine failure at the worst possible moment, you have to have multiple engines. The difficulty of deep throttling an engine increases in a non-linear way, so 2:1 is fairly easy, but a deep 5:1 is very hard. Granularity is also a big factor. If you just have two engines that do everything, the engine complexity is much higher and, if one fails, you've lost half your power. Btw, we modified the BFS design since IAC to add a third medium area ratio Raptor engine partly for that reason (lose only 1/3 thrust in engine out) and allow landings with higher payload mass for the Earth to Earth transport function.

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Re: TED talk by Gwynne Shotwell
« Reply #102 on: 04/23/2018 10:23 PM »
Iím not a biologist. Yet I am aware of these changes (and indeed, many are incredibly exciting), but few are relevant to interstellar travel in a way that couldnít be sent to the ship while in transit.

Wow.  Never thought of that before.

You are sort of suggesting that, once we've got the ability to "3D print" lab equipment and so forth that would be sufficient to assemble a human being from raw materials, that we just build a probe loaded with that "3D printer" and raw materials, and fire that on a 1000-year journey to various stars.

While it's on the way, we'll develop the technology for whatever we'll want to have when it gets there, and then send it the plans.  If we want to have people out there to explore the new system, it'll print those too.

I'd never thought of that before.  Seems like an interesting Sci Fi story concept.  The protagonist wakes up in a probe ship 10 lifetimes' journey from the nearest other person....

Yep, that's the way to do it. It's an idea that has long been around. Though the names of things have changed, for 3D printers see von neumann machines or self replicating spacecraft.

What's old is new again.

Offline vaporcobra

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Re: TED talk by Gwynne Shotwell
« Reply #103 on: 04/23/2018 11:28 PM »
Better image quality did make it clear that the "new" BFS still has 2 engines.
I believe that's the same video from last September.

Since then, Elon said said it will have 3 engines. Specifically:
https://www.reddit.com/r/space/comments/76e79c/i_am_elon_musk_ask_me_anything_about_bfr/
Quote
In order to be able to land the BF Ship with an engine failure at the worst possible moment, you have to have multiple engines. The difficulty of deep throttling an engine increases in a non-linear way, so 2:1 is fairly easy, but a deep 5:1 is very hard. Granularity is also a big factor. If you just have two engines that do everything, the engine complexity is much higher and, if one fails, you've lost half your power. Btw, we modified the BFS design since IAC to add a third medium area ratio Raptor engine partly for that reason (lose only 1/3 thrust in engine out) and allow landings with higher payload mass for the Earth to Earth transport function.

100% not the same video. Only video released in 2017 was the Earth-to-Earth transport video, while the BFR vid shown at TED2018 is a shot-for-shot remake of the 2016 ITS reveal, just with the 3D models swapped. Presumably technically inaccurate in its inclusion of only two SL Raptors.

Offline rockets4life97

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Re: TED talk by Gwynne Shotwell
« Reply #104 on: 04/24/2018 12:47 AM »
Did we already know that BFR would have an 8 meter fairing? That was new info to me, although not surprising.

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Re: TED talk by Gwynne Shotwell
« Reply #105 on: 04/24/2018 01:14 AM »
Better image quality did make it clear that the "new" BFS still has 2 engines.
I believe that's the same video from last September.

Since then, Elon said said it will have 3 engines. Specifically:
https://www.reddit.com/r/space/comments/76e79c/i_am_elon_musk_ask_me_anything_about_bfr/
Quote
In order to be able to land the BF Ship with an engine failure at the worst possible moment, you have to have multiple engines. The difficulty of deep throttling an engine increases in a non-linear way, so 2:1 is fairly easy, but a deep 5:1 is very hard. Granularity is also a big factor. If you just have two engines that do everything, the engine complexity is much higher and, if one fails, you've lost half your power. Btw, we modified the BFS design since IAC to add a third medium area ratio Raptor engine partly for that reason (lose only 1/3 thrust in engine out) and allow landings with higher payload mass for the Earth to Earth transport function.

100% not the same video. Only video released in 2017 was the Earth-to-Earth transport video, while the BFR vid shown at TED2018 is a shot-for-shot remake of the 2016 ITS reveal, just with the 3D models swapped. Presumably technically inaccurate in its inclusion of only two SL Raptors.
Or the 3 SLR design was considered and rejected in the last 6 months...

Offline acsawdey

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Re: TED talk by Gwynne Shotwell
« Reply #106 on: 04/24/2018 01:23 AM »
Or the 3 SLR design was considered and rejected in the last 6 months...

One possible reason for this would be that Raptor development is going better than expected. If Raptor can run at a higher chamber pressure (more than the 250 bar that was stated at 2017 IAC) then the two sea level raptors have more thrust and more margin.

Offline rockets4life97

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Re: TED talk by Gwynne Shotwell
« Reply #107 on: 04/24/2018 01:25 AM »
Or the 3 SLR design was considered and rejected in the last 6 months...

One possible reason for this would be that Raptor development is going better than expected. If Raptor can run at a higher chamber pressure (more than the 250 bar that was stated at 2017 IAC) then the two sea level raptors have more thrust and more margin.

I thought the reasoning for 3 was to add an additional engine out capability for landing.

Offline Inoeth

Re: TED talk by Gwynne Shotwell
« Reply #108 on: 04/24/2018 01:31 AM »
Better image quality did make it clear that the "new" BFS still has 2 engines.
I believe that's the same video from last September.

Since then, Elon said said it will have 3 engines. Specifically:
https://www.reddit.com/r/space/comments/76e79c/i_am_elon_musk_ask_me_anything_about_bfr/
Quote
In order to be able to land the BF Ship with an engine failure at the worst possible moment, you have to have multiple engines. The difficulty of deep throttling an engine increases in a non-linear way, so 2:1 is fairly easy, but a deep 5:1 is very hard. Granularity is also a big factor. If you just have two engines that do everything, the engine complexity is much higher and, if one fails, you've lost half your power. Btw, we modified the BFS design since IAC to add a third medium area ratio Raptor engine partly for that reason (lose only 1/3 thrust in engine out) and allow landings with higher payload mass for the Earth to Earth transport function.

100% not the same video. Only video released in 2017 was the Earth-to-Earth transport video, while the BFR vid shown at TED2018 is a shot-for-shot remake of the 2016 ITS reveal, just with the 3D models swapped. Presumably technically inaccurate in its inclusion of only two SL Raptors.
Or the 3 SLR design was considered and rejected in the last 6 months...

Yeah, since Elon has noted that BFR has been stretched a little bit, perhaps the potential up-rating of the Raptor engine has allowed them to skip that 3rd engine on BFS after all.. Or, quite possibly it was a very quick editing job in terms of replacing BFR 3d models with the old ITS video and that it's not completely accurate as to the exact layout of BFR/S...

Did we already know that BFR would have an 8 meter fairing? That was new info to me, although not surprising.

That details has been indeed speculated but that number hasn't been specifically known. I do have to wonder about the tapering of the nose of the ship and therefore of the fairing space resulting in perhaps not quite as much fairing space as they'd want... Still, it's going to be a far larger fairing space compared to anything that's flown in the past and should really open the doors to some cool satellites and large telescopes in the future - not to mention bulk satellite deployments on a scale that make what SpaceX currently does with IridiumNext seem small...

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #109 on: 04/24/2018 02:19 AM »
Still, it's going to be a far larger fairing space compared to anything that's flown in the past and should really open the doors to some cool satellites and large telescopes in the future - not to mention bulk satellite deployments on a scale that make what SpaceX currently does with IridiumNext seem small...

Yep.

(graphics by lamontagne)
« Last Edit: 04/24/2018 02:21 AM by Dave G »

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Re: TED talk by Gwynne Shotwell
« Reply #111 on: 04/24/2018 10:05 PM »
Or the 3 SLR design was considered and rejected in the last 6 months...

Yeah, since Elon has noted that BFR has been stretched a little bit, perhaps the potential up-rating of the Raptor engine has allowed them to skip that 3rd engine on BFS after all.. Or, quite possibly it was a very quick editing job in terms of replacing BFR 3d models with the old ITS video and that it's not completely accurate as to the exact layout of BFR/S...

As far as I remember Musk walked back to two SLRs earlier this year, but I cannot find my old comment with the reference. Maybe it was in one of the several interviews when Falcon Heavy went up, so it was little noticed?

But what was news for me was that the propellant feeds have moved for the second time, to the outside of the engine compartment/hull.

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Re: TED talk by Gwynne Shotwell
« Reply #112 on: 04/25/2018 01:24 AM »
Or the 3 SLR design was considered and rejected in the last 6 months...

Yeah, since Elon has noted that BFR has been stretched a little bit, perhaps the potential up-rating of the Raptor engine has allowed them to skip that 3rd engine on BFS after all.. Or, quite possibly it was a very quick editing job in terms of replacing BFR 3d models with the old ITS video and that it's not completely accurate as to the exact layout of BFR/S...

As far as I remember Musk walked back to two SLRs earlier this year, but I cannot find my old comment with the reference. Maybe it was in one of the several interviews when Falcon Heavy went up, so it was little noticed?

But what was news for me was that the propellant feeds have moved for the second time, to the outside of the engine compartment/hull.
Pretty sure those are legs.

Offline niwax

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Re: TED talk by Gwynne Shotwell
« Reply #113 on: 04/25/2018 07:36 AM »
Or the 3 SLR design was considered and rejected in the last 6 months...

Yeah, since Elon has noted that BFR has been stretched a little bit, perhaps the potential up-rating of the Raptor engine has allowed them to skip that 3rd engine on BFS after all.. Or, quite possibly it was a very quick editing job in terms of replacing BFR 3d models with the old ITS video and that it's not completely accurate as to the exact layout of BFR/S...

As far as I remember Musk walked back to two SLRs earlier this year, but I cannot find my old comment with the reference. Maybe it was in one of the several interviews when Falcon Heavy went up, so it was little noticed?

But what was news for me was that the propellant feeds have moved for the second time, to the outside of the engine compartment/hull.

A question concerning BFS SSTO: How would that work with only two SL raptors? Wikipedia currently lists SL at 1700kN and Vac at 1900kN. Two SL Raptors on a 1185t fueled BFS would give barely a 0.29 TWR, even if the vacuum engines could be run at full thrust in the atmosphere it'd only get up to 0.95 TWR.

Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #114 on: 04/25/2018 08:09 AM »
A question concerning BFS SSTO: How would that work with only two SL raptors? Wikipedia currently lists SL at 1700kN and Vac at 1900kN. Two SL Raptors on a 1185t fueled BFS would give barely a 0.29 TWR, even if the vacuum engines could be run at full thrust in the atmosphere it'd only get up to 0.95 TWR.

Either you don't quite put all the fuel in, or you put more engines on. (the first of course leads to zero payload if it can do SSTO at all)

It seems reasonable to assume that you can unbolt vacuum raptor, and replace with SL - at least at this point in the design if that was desired.
Do that for the four engines if they cannot repeatably be run at full thrust.

Add two engines to the cluster of SL raptors, and we're now at T:W of 1.15 - not exactly sporty, but sort-of reasonable.

Of course, if those four circular things outboard are in fact very low area ratio raptors, there is no need for more engines.

If they are, there may be margin to leave a couple of vacuum raptors on.

There are lots of caveats for it to work meaningfully as SSTO, and some choices to optimise it need to be made early - but they do not on the face of it seem to be choices that make the normal variant of the vehicle more difficult.

See the extensive discussion in this thread

Offline guckyfan

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Re: TED talk by Gwynne Shotwell
« Reply #115 on: 04/25/2018 11:21 AM »
When Elon first mentioned BFS tests with orbital speed, he said it would require the vac engines. They can be fired at SL with full thrust.

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Re: TED talk by Gwynne Shotwell
« Reply #116 on: 04/25/2018 02:51 PM »
But what was news for me was that the propellant feeds have moved for the second time, to the outside of the engine compartment/hull.
Pretty sure those are legs.
Yes that looks like legs to me as well.

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Re: TED talk by Gwynne Shotwell
« Reply #117 on: 04/25/2018 04:14 PM »
When Elon first mentioned BFS tests with orbital speed, he said it would require the vac engines. They can be fired at SL with full thrust.

Yes, but here is the full quote: https://www.reddit.com/r/space/comments/76e79c/i_am_elon_musk_ask_me_anything_about_bfr/dodhsw6/
Quote
"The "vacuum" or high area ratio Raptors can operate at full thrust at sea level. Not recommended."

Offline guckyfan

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Re: TED talk by Gwynne Shotwell
« Reply #118 on: 04/25/2018 08:28 PM »
There was another quote, directly related to BFS tests. Basically it was initial hops would use only the central engines, not the vac engines and no heatshield. Then tests of reentry from orbital speeds which would require both.

I am very much aware of the Not recommended. I argue it as meaning SSTO operations is not recommended. But that is a different remark. It can be done for reentry tests.

Offline Darkseraph

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Re: TED talk by Gwynne Shotwell
« Reply #119 on: 04/26/2018 10:51 AM »
Gwynne mentioned the diameter of the fairing being 8 meters for BFR allowing very large sats. Has the BFR stack shrunk in diameter since 2017?
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Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #120 on: 04/26/2018 11:05 AM »
Gwynne mentioned the diameter of the fairing being 8 meters for BFR allowing very large sats. Has the BFR stack shrunk in diameter since 2017?
No.

The BFS chomper payload area is smaller than the diameter of the tanks.

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Re: TED talk by Gwynne Shotwell
« Reply #121 on: 04/26/2018 04:45 PM »
SpaceX showed pictures of BFS's landed in exotic locations like asteroids or Jupiter's moons.  Those would be very hard to get back.  If they fueled in Mars orbit, they could send a probe with another propulsion module off to a much faster trip outbound, but we're still talking about a trip beyond its designed capabilities.
Hard to get back if you're doing a one shot. But that's the wrong way to think about this. Jupiter's moons are just another destination that needs infrastructure emplaced enroute.

Stop thinking flags and footprints, and start thinking about transportation network extension, step by step. Railways managed to get all the way from Omaha to San Francisco, despite locomotives only being able to carry water for maybe 100 miles of travel and fuel for 2-300. At most.  It was done incrementally. As the track was extended, gangs followed behind building wells, dams, water tanks, coaling depots, maintenance facilities, crew lodging, freight depots, and all the rest. All the materials they couldn't ISRU (everything except maybe timbers and rocks and dirt) were brought along, and as facilities were built, it got easier and easier to bring more materials.

(fan to mod transition) Also, the concept of interstellar is not off topic., She mentioned it. But detailed discussion of how to do it in general? Off topic beacuse we have lots of other threads.
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Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #122 on: 04/26/2018 05:14 PM »
Gwynne mentioned the diameter of the fairing being 8 meters for BFR allowing very large sats. Has the BFR stack shrunk in diameter since 2017?

More or less makes sense if it's interior vs exterior diameter.

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Re: TED talk by Gwynne Shotwell
« Reply #123 on: 04/26/2018 05:38 PM »
Gwynne mentioned the diameter of the fairing being 8 meters for BFR allowing very large sats. Has the BFR stack shrunk in diameter since 2017?

More or less makes sense if it's interior vs exterior diameter.
I agree. I think sheís citing an estimate of useable interior diameter not exterior diameter. From a payload perspective that is the relevant measurement.

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Re: TED talk by Gwynne Shotwell
« Reply #124 on: 04/27/2018 08:54 AM »
SpaceX showed pictures of BFS's landed in exotic locations like asteroids or Jupiter's moons.  Those would be very hard to get back.  If they fueled in Mars orbit, they could send a probe with another propulsion module off to a much faster trip outbound, but we're still talking about a trip beyond its designed capabilities.
Hard to get back if you're doing a one shot. But that's the wrong way to think about this. Jupiter's moons are just another destination that needs infrastructure emplaced enroute.

Stop thinking flags and footprints, and start thinking about transportation network extension, step by step. Railways managed to get all the way from Omaha to San Francisco, despite locomotives only being able to carry water for maybe 100 miles of travel and fuel for 2-300. At most.  It was done incrementally. As the track was extended, gangs followed behind building wells, dams, water tanks, coaling depots, maintenance facilities, crew lodging, freight depots, and all the rest. All the materials they couldn't ISRU (everything except maybe timbers and rocks and dirt) were brought along, and as facilities were built, it got easier and easier to bring more materials.

(fan to mod transition) Also, the concept of interstellar is not off topic., She mentioned it. But detailed discussion of how to do it in general? Off topic beacuse we have lots of other threads.

I guess this is where companies like Planetary Resources will make money. Deep space refuelling depots and extensive asteroid mining throughout the system to produce propellant and other consumables.

Later maturing into something like the Transport Union of the Expanse series or the Spacing Guild.

Offline Ludus

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Re: TED talk by Gwynne Shotwell
« Reply #125 on: 04/28/2018 05:28 AM »
I was impressed at how confident she was about point to point and the numbers she confirmed or mentioned for that. They really are looking at flying it 10X a day, every day. Thereís really no difference between that application and orbital transport. I guess they plan to be able to fill the whole thing with propellant and launch in less than 2 hours. Questioned about whether governments will allow it, she said it wouldnít have seemed likely the USAF would allow F9 boosters to fly back to their property and this is 10 km off shore.

It makes sense as an important part of driving reusability harder than any conventional space application. It wouldnít really matter to SpaceX if they can make money at it, as long as they donít lose too much and it subsidizes the perfection of gas and go reusability for space launch.


Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #126 on: 04/28/2018 08:56 AM »
I guess they plan to be able to fill the whole thing with propellant and launch in less than 2 hours.
The main phase of filling the propellant in F9 and launching takes under half an hour, with most completed in 15 minutes.
It starts only about an hour and twenty minutes before launch.

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #127 on: 04/28/2018 12:50 PM »
Questioned about whether governments will allow it, she said it wouldnít have seemed likely the USAF would allow F9 boosters to fly back to their property and this is 10 km off shore.

By the way, this is the first time we've gotten any numbers from SpaceX as to how far offshore the BFR launch pad will be.  Gwynne actually mentioned both 5km and 10km as possibilities.

So that's a range of 3.1 to 6.2 miles offshore.  Previously, I'd speculated somewhere around 5 miles offshore, so that seems to be about right.

Re: TED talk by Gwynne Shotwell
« Reply #128 on: 04/28/2018 01:09 PM »
I've read sound propagates better over water. Are there any calculations on the acoustic pollution produced by a BFR 5-10km offshore a major city?
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Offline philw1776

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Re: TED talk by Gwynne Shotwell
« Reply #129 on: 04/28/2018 01:14 PM »
I've read sound propagates better over water. Are there any calculations on the acoustic pollution produced by a BFR 5-10km offshore a major city?

Yes it does propagate well.  I am very familiar with the Isle of Shoals ~6 miles off the NH coast and city of Portsmouth. I would be seriously surprised if any commercial passenger launch site outside a major city, assuming any are ever built, is less than 10 miles or 16Km offshore.  These are very big rockets.
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Re: TED talk by Gwynne Shotwell
« Reply #130 on: 04/28/2018 01:27 PM »
I've read sound propagates better over water. Are there any calculations on the acoustic pollution produced by a BFR 5-10km offshore a major city?

Yes it does propagate well.  I am very familiar with the Isle of Shoals ~6 miles off the NH coast and city of Portsmouth. I would be seriously surprised if any commercial passenger launch site outside a major city, assuming any are ever built, is less than 10 miles or 16Km offshore.  These are very big rockets.

Well even 16km is not that bad. With an hydrofoil it's a 15min ride.
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Offline Ludus

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Re: TED talk by Gwynne Shotwell
« Reply #131 on: 04/29/2018 07:16 AM »
I guess they plan to be able to fill the whole thing with propellant and launch in less than 2 hours.
The main phase of filling the propellant in F9 and launching takes under half an hour, with most completed in 15 minutes.
It starts only about an hour and twenty minutes before launch.

Thatís impressive. That makes 2 hour turn around plausible at least as far as refilling.

Offline Ludus

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Re: TED talk by Gwynne Shotwell
« Reply #132 on: 04/29/2018 07:23 AM »
I've read sound propagates better over water. Are there any calculations on the acoustic pollution produced by a BFR 5-10km offshore a major city?

Yes it does propagate well.  I am very familiar with the Isle of Shoals ~6 miles off the NH coast and city of Portsmouth. I would be seriously surprised if any commercial passenger launch site outside a major city, assuming any are ever built, is less than 10 miles or 16Km offshore.  These are very big rockets.

I wonder if there are sound suppression techniques that might apply to this situation. I understand that the water systems used at some pads are for this. If itís a pad at sea there might be new approaches to suppressing sound in the direction of the city.

Offline Dave G

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Re: TED talk by Gwynne Shotwell
« Reply #133 on: 04/29/2018 09:37 AM »
The President and Chief Operating Officer of SpaceX said 5-10km offshore.  She wouldn't have said that unless SpaceX had analyzed all aspects of the offshore pad at those distances, including sound.

In the absence of any information, speculation is fine. It's part of what makes this a great forum.

But when we have it straight from the horse's mouth, speculation otherwise seems pointless.

Offline niwax

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Re: TED talk by Gwynne Shotwell
« Reply #134 on: 04/29/2018 12:57 PM »
I've read sound propagates better over water. Are there any calculations on the acoustic pollution produced by a BFR 5-10km offshore a major city?

Yes it does propagate well.  I am very familiar with the Isle of Shoals ~6 miles off the NH coast and city of Portsmouth. I would be seriously surprised if any commercial passenger launch site outside a major city, assuming any are ever built, is less than 10 miles or 16Km offshore.  These are very big rockets.

I wonder if there are sound suppression techniques that might apply to this situation. I understand that the water systems used at some pads are for this. If itís a pad at sea there might be new approaches to suppressing sound in the direction of the city.

Sound travels well over water because it's a perfectly flat surface. Maybe some installation around the pad to deflect the sound waves slightly upwards?

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Re: TED talk by Gwynne Shotwell
« Reply #135 on: 04/29/2018 01:15 PM »
Sound travels well over water because it's a perfectly flat surface. Maybe some installation around the pad to deflect the sound waves slightly upwards?

The rocket travels upwards too, quite a long way up. I can't think how you could shield from that.
« Last Edit: 04/29/2018 01:15 PM by nacnud »

Offline philw1776

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Re: TED talk by Gwynne Shotwell
« Reply #136 on: 04/29/2018 01:38 PM »
The President and Chief Operating Officer of SpaceX said 5-10km offshore.  She wouldn't have said that unless SpaceX had analyzed all aspects of the offshore pad at those distances, including sound.

In the absence of any information, speculation is fine. It's part of what makes this a great forum.

But when we have it straight from the horse's mouth, speculation otherwise seems pointless.

For example, many of us here speculated that BFR specs from horses mouth at IAC 2016 would change.  They did. 
When far off plans meet reality, especially when they are not engineering constrained, but regulatory, they have an even greater risk of change. 
SpaceX statements are not stone tablets to be worshiped without question, but current plans subject to change over the many years before possible fruition.  I had thought SpaceX was notable for its ability to change course on the fly to adapt to reality intrusions and opportunities previously unknown or not sufficiently vetted.  I doubt that BFR P2P is sufficiently vetted as of 2017.
« Last Edit: 04/29/2018 01:41 PM by philw1776 »
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Offline deruch

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Re: TED talk by Gwynne Shotwell
« Reply #137 on: 04/29/2018 03:28 PM »
Sound travels well over water because it's a perfectly flat surface. Maybe some installation around the pad to deflect the sound waves slightly upwards?

The rocket travels upwards too, quite a long way up. I can't think how you could shield from that.

The issue, if there is one, is going to be less about the sound of the rockets as the vehicles leave and more about incoming vehicles creating very large sonic booms.
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Offline CapitalistOppressor

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Re: TED talk by Gwynne Shotwell
« Reply #138 on: 04/30/2018 02:42 AM »
A more mundane possibility: Asking about stuff that would happen 20/35/50 years from now is a bit ridiculous from Gwynnes perspective. She is responsible for the economic success of SpaceX. She has necessarily a horizon of maybe 5 years or some more in some long term development projects. From her perspective, talking about stuff that is 4 to 10 times her current time horizon, there is no way she can give a sensible answer. So she gives intentionally a ridiculous one.

I live in LA and run across SpaceX people all the time, including propulsion types. 

I've had, and overheard, multiple conversations that imply, or flat out state, that these guys expect to be working on advanced propulsion as soon as they finish Raptor/BFR. 

Some were actually bored with Raptor development, which they think is not really that advanced of a propulsion concept.  Just highly necessary, and better than anything else available.


Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #139 on: 04/30/2018 03:13 AM »
If you're doing point-to-point transport using a highly reusable system and fuel that is produced via electrolysis (indirectly for methane), then the fuel energy costs ends up being a driver of the overall system costs.

Besides the usual performance improvements like higher chamber pressure, thrust-to-weight, etc, that drives you to playing with mixture ratios and using hydrogen instead of methane. Again, if you're making the fuel electrically.

Nuclear thermal only really helps much for high speed beyond-LEO orbits. Anything else just ends up being suboptimal, energy-wise.

So although SpaceX has not pursued hydrogen for a while, I expect them to return to it eventually. And yeah, nuclear thermal probably, too, in order to reduce Mars transit times to below 40 days.
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Re: TED talk by Gwynne Shotwell
« Reply #140 on: 04/30/2018 03:59 AM »
If you're doing point-to-point transport using a highly reusable system and fuel that is produced via electrolysis (indirectly for methane), then the fuel energy costs ends up being a driver of the overall system costs.

Besides the usual performance improvements like higher chamber pressure, thrust-to-weight, etc, that drives you to playing with mixture ratios and using hydrogen instead of methane. Again, if you're making the fuel electrically.

Nuclear thermal only really helps much for high speed beyond-LEO orbits. Anything else just ends up being suboptimal, energy-wise.

So although SpaceX has not pursued hydrogen for a while, I expect them to return to it eventually. And yeah, nuclear thermal probably, too, in order to reduce Mars transit times to below 40 days.
None of that changes the problems associated with long term hydrogen storage. I would prefer to bet on SpaceX designing around a different fuel- whether it be a Carbon Monoxide marshopper engine, A Bussard Ramscoop Ion engine (ok, this might be hydrogen), or an Oxygen or even Carbon or Carbon Monoxide based Nuclear Thermal rocket.

Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #141 on: 04/30/2018 04:02 AM »
You skimmed my post but didn't read it. Long term on-orbit storage is irrelevant for point-to-point transport. Also is a solvable problem.
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Re: TED talk by Gwynne Shotwell
« Reply #142 on: 04/30/2018 04:39 AM »
For earth surface to surface, Hydrogen suffers from bad mass ratios and, relatedly, higher atmospheric drag per unit fuel. On paper it appears to be best only because engine math doesnt include tank differences.

Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #143 on: 04/30/2018 12:27 PM »
For earth surface to surface, Hydrogen suffers from bad mass ratios and, relatedly, higher atmospheric drag per unit fuel. On paper it appears to be best only because engine math doesnt include tank differences.
Iím well aware of all that! However: Mass ratios can be improved with improved structural technology. And hydrolox mass ratios are actually pretty good if running ox-rich (which you might for a first stage).

Iím not just saying hydrogen because of the Isp but because it takes less energy to produce (for the same chemical energy) than methane due to the inefficiency of the Sabatier Reaction. And having to capture CO2 from the air is actually pretty difficult on Earth.

SpaceX is probably right to do methane for BFR. But long term, they should look at highly variable mix ratio hydrolox (including thrust augmentation).

Just one example of advanced propulsion technology.
« Last Edit: 04/30/2018 12:31 PM by Robotbeat »
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Offline Torbjorn Larsson, OM

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Re: TED talk by Gwynne Shotwell
« Reply #144 on: 04/30/2018 01:51 PM »
Re sonic booms, if BFS is used for suborbital P2P how much of a propellant reserve would it have coming down? It may alleviate strength of local booms by going subsonic some ways up.

If you're doing point-to-point transport using a highly reusable system and fuel that is produced via electrolysis (indirectly for methane), then the fuel energy costs ends up being a driver of the overall system costs.

Is it that costly? I know nothing about airplane traffic, but comparatively an airline operating cost is ~ 50 % aircraft operating expense of which propane fuel is ~ 20 %, so 10 % of total cost [ https://www.icao.int/MID/Documents/2017/Aviation%20Data%20and%20Analysis%20Seminar/PPT3%20-%20Airlines%20Operating%20costs%20and%20productivity.pdf ].

Conversely, air breathing airplanes will as far as I know likely never use hydrogen fuel due to the outsized tanks needed. The current 5 certified green fuels are hydrocarbon based with up to 50 % mixing with "Jet A1" fuel [ https://www.nyteknik.se/premium/5-vagar-till-gront-biobransle-6911555 ].

It is an interesting hypothesis, but the rationale is not obvious to me. How much would electrolysis really cost? When would that cost be a driver for technology change, when it hits 20 % or > 50 % of operating cost? At 10 % of operating cost the current industry is unwilling to change to greener fuel - passengers now have to buy "green tickets" to support green mixing - but seems happy with hydrocarbon fuel as such.

Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #145 on: 04/30/2018 02:04 PM »
Rockets can do an order of magnitude more long-haul flights per day than a jet can, so capital costs and crew labor costs are actually potentially lower than with airliners. But it takes a bit more energy, and therefore fuel costs end up being important.

Synthetic methane (ie from electrolyzed hydrogen) is not competitive with conventional methane. Heck, fossil-derived hydrogen is cheaper than electrolyzed hydrogen, which means electrolysis is more expensive than fossil fuels right now. Hydrogen would have lower electrolysis costs than methane and is significantly simpler to produce (except for liquefaction).
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Re: TED talk by Gwynne Shotwell
« Reply #146 on: 04/30/2018 02:27 PM »
Re sonic booms, if BFS is used for suborbital P2P how much of a propellant reserve would it have coming down? It may alleviate strength of local booms by going subsonic some ways up.

P2P would likely be orbital or near-orbital, as it reduces the g-loads on reentry especially for very long range flights, and reduces the required apogee (and thus radiation exposure), which is 4000 to 5000 km for 10000 km flight ranges.

For shorter flights like transatlantic they might be able to use a suborbital trajectory with a skip entry, which trades speed for altitude and more range, using the vehicles' lifting ability. The Shuttle traveled 5,000 km in the atmosphere during reentry, which is about the transatlantic distance.

BFS would probably slow subsonic high enough and far enough away from the landing site that it wouldn't have a problematic sonic boom if it was approaching over water. It has a much better glide ratio and lower terminal velocity than the Falcon booster.

However, the BFB does not. Any launch with a BFB will have sonic booms near the launch/landing site.

Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #147 on: 04/30/2018 02:35 PM »
No point in subsonic P2P. Besides, engine exhaust is supersonic so wouldnít be much quieter.
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Offline philw1776

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Re: TED talk by Gwynne Shotwell
« Reply #148 on: 04/30/2018 03:59 PM »
A more mundane possibility: Asking about stuff that would happen 20/35/50 years from now is a bit ridiculous from Gwynnes perspective. She is responsible for the economic success of SpaceX. She has necessarily a horizon of maybe 5 years or some more in some long term development projects. From her perspective, talking about stuff that is 4 to 10 times her current time horizon, there is no way she can give a sensible answer. So she gives intentionally a ridiculous one.

I live in LA and run across SpaceX people all the time, including propulsion types. 

I've had, and overheard, multiple conversations that imply, or flat out state, that these guys expect to be working on advanced propulsion as soon as they finish Raptor/BFR. 

Some were actually bored with Raptor development, which they think is not really that advanced of a propulsion concept.  Just highly necessary, and better than anything else available.

Congruent with Tom Mueller's stated enthusiasm for nuclear propulsion.
Not that it would be public but I long wondered if Musk shouldn't spend a few million here and there investing in longshot fusion startups applicable to spaceflight, q.v. those producing electricity directly.
SpaceX is already into ion propulsion for its satellites.  Problem with that tech is even huge cluster arrays of ion jets produce too little thrust for heavy manned ships to Mars. 
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Offline WindyCity

Re: TED talk by Gwynne Shotwell
« Reply #149 on: 04/30/2018 07:40 PM »

So that's a range of 3.1 to 6.2 miles offshore.  Previously, I'd speculated somewhere around 5 miles offshore, so that seems to be about right.

One possible objection to the system operating near heavily populated areas would be noise. Sound travels a long distance over unobstructed water. It strikes me that the giant rocket could rattle windows at 5km.

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Re: TED talk by Gwynne Shotwell
« Reply #150 on: 04/30/2018 08:45 PM »

So that's a range of 3.1 to 6.2 miles offshore.  Previously, I'd speculated somewhere around 5 miles offshore, so that seems to be about right.

One possible objection to the system operating near heavily populated areas would be noise. Sound travels a long distance over unobstructed water. It strikes me that the giant rocket could rattle windows at 5km.
See discussion, last page, upthread https://forum.nasaspaceflight.com/index.php?topic=45461.msg1815356#msg1815356
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Offline ThereIWas3

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Re: TED talk by Gwynne Shotwell
« Reply #151 on: 04/30/2018 09:46 PM »
I can hear the larger rockets launched from KSC from my front yard, 90 miles away.  6mi inland from the Atlantic coast.  Hardly window rattling at that distance but audible.  The SLS was louder than FH, especially if you are out at the beach.   I was not living here during the Saturn-V era so can't speak to that but I would expect BFR to be louder than that was.   The SX launch facility in TX is surrounded by protected wildlife areas and ritzy resort areas a good deal closer than I am to KSC.
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Offline Elmar Moelzer

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Re: TED talk by Gwynne Shotwell
« Reply #152 on: 04/30/2018 10:37 PM »
Congruent with Tom Mueller's stated enthusiasm for nuclear propulsion.
Not that it would be public but I long wondered if Musk shouldn't spend a few million here and there investing in longshot fusion startups applicable to spaceflight, q.v. those producing electricity directly.
I would go with systems that directly convert the fusion output into thrust. MSNW LLC has the fusion driven rocket, which is a really cool system with a good amount of thrust and ISP and I also really like what PPPL and PSS are doing with their FRC based Direct Fusion Drive. Both of them would enable very short transit times. And then there are a couple of other fusion reactor designs that could work out well. I think that once one fusion company demonstrates a Q>1, Musk (and others) will take a closer look at this.

Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #153 on: 05/01/2018 12:02 AM »
Fusion is vaporware offtopic.
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Offline Star One

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TED talk by Gwynne Shotwell
« Reply #154 on: 05/01/2018 06:26 AM »
Fusion is vaporware offtopic.

This comment makes it look like you donít know what the definition of vapourware is, and is somewhat insulting to those working in the area.
« Last Edit: 05/01/2018 06:30 AM by Star One »

Offline aero

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Re: TED talk by Gwynne Shotwell
« Reply #155 on: 05/01/2018 06:37 AM »
For those who are unaware of the "Great Fusion Debate," read all about it here:

http://www.talk-polywell.org/bb/viewforum.php?f=10

Talk-Polywell still follows the Polywell reactor concept but in the previous years has expanded to discuss all of the of the different fusion concepts. If you know of a concept that is not discussed there, please bring it to our attention at Talk-Polywell.
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Re: TED talk by Gwynne Shotwell
« Reply #156 on: 05/02/2018 04:14 PM »
BFS would probably slow subsonic high enough and far enough away from the landing site that it wouldn't have a problematic sonic boom if it was approaching over water. It has a much better glide ratio and lower terminal velocity than the Falcon booster.
Sounds like those wings will be getting a bit bigger.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Hominans Kosmos

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Re: TED talk by Gwynne Shotwell
« Reply #157 on: 05/05/2018 03:50 PM »
BFS would probably slow subsonic high enough and far enough away from the landing site that it wouldn't have a problematic sonic boom if it was approaching over water. It has a much better glide ratio and lower terminal velocity than the Falcon booster.
Sounds like those wings will be getting a bit bigger.

Why would they be making the negative lift trim surfaces bigger? Wouldn't just changing their shape and placement change angle of attack to the desired value for the specific glide ratio?

Offline Hominans Kosmos

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Re: TED talk by Gwynne Shotwell
« Reply #158 on: 05/05/2018 04:07 PM »
Besides the usual performance improvements like <snip> and using hydrogen instead of methane. Again, if you're making the fuel electrically.

So although SpaceX has not pursued hydrogen for a while, I expect them to return to it eventually.

Long term on-orbit storage is irrelevant for point-to-point transport. Also is a solvable problem.

Hydrogen is doubtless a solvable problem. And every solution you come up with is not worth the added cost in dollars.

The entire storage - transportation - loading - storing - design - fabrication - using chain gets meaningfully more expensive as soon as you introduce hydrogen to it.

If I would expect to see that to become a near term reality I could bet a small amount of money on hydrogen never being competitive even if the cost of electrolysis and electricity goes so low electrolysed synthetic methane becomes cheaper than any and all natural gas. That in such a case your operations, safety and hardware all combined end up cheaper if you compare hydrogen against methane.

Hydrogen is a solvable problem, at a higher ticket price per passenger seat mile.
« Last Edit: 05/05/2018 04:09 PM by Hominans Kosmos »

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Re: TED talk by Gwynne Shotwell
« Reply #159 on: 05/05/2018 04:11 PM »

I live in LA and run across SpaceX people all the time, including propulsion types. 

I've had, and overheard, multiple conversations that imply, or flat out state, that these guys expect to be working on advanced propulsion as soon as they finish Raptor/BFR. 

Some were actually bored with Raptor development, which they think is not really that advanced of a propulsion concept.  Just highly necessary, and better than anything else available.

Congruent with Tom Mueller's stated enthusiasm for nuclear propulsion.
Not that it would be public but I long wondered if Musk shouldn't spend a few million here and there investing in longshot fusion startups applicable to spaceflight, q.v. those producing electricity directly.
SpaceX is already into ion propulsion for its satellites.  Problem with that tech is even huge cluster arrays of ion jets produce too little thrust for heavy manned ships to Mars.

I would actually think about arcject engine. Would benefit both launchers and in space propulsion.
And Elon actually mentioned it in Iron Man 2 :)

Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #160 on: 05/05/2018 05:06 PM »
Besides the usual performance improvements like <snip> and using hydrogen instead of methane. Again, if you're making the fuel electrically.

So although SpaceX has not pursued hydrogen for a while, I expect them to return to it eventually.

Long term on-orbit storage is irrelevant for point-to-point transport. Also is a solvable problem.

Hydrogen is doubtless a solvable problem. And every solution you come up with is not worth the added cost in dollars.

The entire storage - transportation - loading - storing - design - fabrication - using chain gets meaningfully more expensive as soon as you introduce hydrogen to it.

If I would expect to see that to become a near term reality I could bet a small amount of money on hydrogen never being competitive even if the cost of electrolysis and electricity goes so low electrolysed synthetic methane becomes cheaper than any and all natural gas. That in such a case your operations, safety and hardware all combined end up cheaper if you compare hydrogen against methane.

Hydrogen is a solvable problem, at a higher ticket price per passenger seat mile.
Hydrogen is terrible for cars, but if you get high enough scale, it may make sense for things that can’t be easily electrified (like rockets). When the cost of fuel becomes dominant, then it should be considered.

I like methane as a rocket fuel and it’s the best choice for BFR right now, but sorry if I’m not in the hydrogen-phobia cult.
« Last Edit: 05/05/2018 05:21 PM by Robotbeat »
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Offline guckyfan

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Re: TED talk by Gwynne Shotwell
« Reply #161 on: 05/05/2018 05:12 PM »
Hydrogen on earth may make sense once we have started producing fuel from regenerative power sources or nuclear. Not as long as the source are fossil fuels. On Mars hydrogen will be produced as part of methane production. It is an easier step there, going outward.

Offline Hominans Kosmos

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Re: TED talk by Gwynne Shotwell
« Reply #162 on: 05/05/2018 05:39 PM »
Hydrogen is terrible for cars, but if you get high enough scale, it may make sense for things that canít be easily electrified (like rockets). When the cost of fuel becomes dominant, then it should be considered.

I like methane as a rocket fuel and itís the best choice for BFR right now, but sorry if Iím not in the hydrogen-phobia cult.

Hydrogen on earth may make sense once we have started producing fuel from regenerative power sources or nuclear. Not as long as the source are fossil fuels. On Mars hydrogen will be produced as part of methane production. It is an easier step there, going outward.

Cost savings in generation (skipping direct conversion to methane or ammonia) are going to be eaten up and negated by cost increases in elevated energy losses in leakage and energy intensity of the distribution and storage network. As well as the cost increases in the infrastructure and utilization hardware. Hydrogen looses all of it's benefits as you zoom out from the trade question whether to bother with anything beyond electrolysis.

The only trade worth doing is how soon after electrolysis you convert hydrogen into a storage molecule.

Pure diatomic hydrogen molecule is not the superior hydrogen storage and distribution technology. It's the more expensive and less infrastructure efficient one.
« Last Edit: 05/05/2018 07:22 PM by Hominans Kosmos »

Offline Robotbeat

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Re: TED talk by Gwynne Shotwell
« Reply #163 on: 05/05/2018 06:36 PM »
That's why hydrogen doesn't make sense for cars or trucks. But if you generate and distribute very near point of use, such as major space ports, then leakage and distribution cost is small.

Hydrogen can make sense at large scale, not at small.

You can't recycle the same arguments against hydrogen fuel cell cars (billions of vehicles, with storage of like a few kilograms of hydrogen for weeks) against something orders of magnitude different in scale and requirements (hundreds of vehicles but only like a few dozen spaceports, with vehicle storage of hundreds of tons for only about an hour). The surface area to volume ratio is vastly different, and the state of matter (liquid vs gas) is also different. You have to recalculate.

It's not about hydrogen being a superior storage method, it's that it has the fewest steps and fewest losses and the disadvantages in terms of mass fraction are less important long-term due to future structural technology improvements. Capturing CO2 out of the air is non-trivial. You're not storing the hydrogen for long.
« Last Edit: 05/05/2018 06:40 PM by Robotbeat »
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Offline Hominans Kosmos

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Re: TED talk by Gwynne Shotwell
« Reply #164 on: 05/05/2018 07:55 PM »
But if you generate and distribute very near point of use, such as major space ports, then leakage and distribution cost is small.

Hydrogen can make sense at large scale, not at small.
Here you replace transportation losses for high energy cost. Spaceport is not located based on minimum energy market prices. It's parked at a large city. Cities are rarely in locations with the cost leading energy generation locations. Saying that just in time on site energy production for a spaceport somehow arrives you at cost savings is not realistic.


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storage of hundreds of tons for only about an hour
Just in time fuel production or compression, cheap?

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The surface area to volume ratio is vastly different, and the state of matter (liquid vs gas) is also different. You have to recalculate.
Upon recalculating, liquid hydrogen does not arrive at a better energy efficiency position than liquid methane.

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It's not about hydrogen being a superior storage method,
It's entirely about which is the better storage method. Better for dollars of energy put in, converted to dollars of passenger seat mile.

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it's that it has the fewest steps
counting chemical processing steps is the wrong proxy for estimating the fuel system cost

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and fewest losses
just shifting energy losses from one part of the chain to another

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You're not storing the hydrogen for long.
operating under such a process assumes on site produced hydrogen, which assumes unfaborable energy prices. Generating your propellant on site next to metropolis X is directly contradictory to lowest possible ticket price for flights.



Apologies are in order. I have to admit it's my fault my objection has been opaque. I will have to be more clear about what I mean to say.

Cheapest hydrogen is cracking natural gas. 
Emerging new energy sources are driving minimum costs of energy down. 
Minimum cost of energy is favorable for the emerging power to gas opportunistic chemical synthesis industry. 
First entrant to power to gas is hydrogen. 
Lowest achievable energy costs are only achieved in favorable geographies.
Hydrogen gas that is cheaper than hydrogen from natural gas is generated in the most favorable locations.
Major metropolitan cities are not usually located where the lowest power cost renewable generators are being built.
Upgrading a natural gas distribution network to a hydrogen distribution network is expensive.
Upgrading a methane burning rocket to a hydrogen burning rocket with the same safety and reliability level is expensive.
Compared to upgrading your natural gas distribution pipelines to hydrogen pipelines, and operating LH2 tankers in stead of LNG tankers is very expensive.
Operating a chemical synthesis factory near your electrolysis factory using the same cheap energy you use for electrolysis, is not significantly more expensive.
Operating an electrolysis factory at your spaceport where energy is more expensive is a waste of money.

Hydrogen dies a death of a thousand paper cuts and none of those are derived from some imaginary anti hydrogen car talking point library you seem to be envisioning. It's basic physics and renewable energy economics. It's not even rocket science!

Online Chris Bergin

Re: TED talk by Gwynne Shotwell
« Reply #165 on: 05/05/2018 08:09 PM »
Per report to mods. Stay on topic of the thread title....

Offline johnfwhitesell

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Re: TED talk by Gwynne Shotwell
« Reply #166 on: 05/08/2018 09:15 PM »
When the cost of fuel becomes dominant, then it should be considered.

We still haven't even reached the point where a car costs less then it's lifetime fuel...  I do admire the forward thinking though!

Offline speedevil

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Re: TED talk by Gwynne Shotwell
« Reply #167 on: 05/08/2018 11:34 PM »
When the cost of fuel becomes dominant, then it should be considered.

We still haven't even reached the point where a car costs less then it's lifetime fuel...  I do admire the forward thinking though!

I recall a post on the highest time 747 retiring in 2009, after having flown 134000 hours.
At $.25/g of fuel at around 1g/s, that is $120M.
Pretty much spot on what it cost on introduction.

In addition, in the UK, with fuel comfortably exceeding $4/g for some time now, the average car (30mpg) only needs to go 100kmiles before fuel costs exceed purchase price.

Looking at the US, with average prices at $33K or so, and 23MPG, and gas price of $2.5, that's 330000 miles.

A substantial minority of private vehicles, and many commercial vehicles will exceed this.


Offline FutureSpaceTourist

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Re: TED talk by Gwynne Shotwell
« Reply #168 on: 05/14/2018 03:30 PM »
Now on YouTube:


Offline philw1776

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Re: TED talk by Gwynne Shotwell
« Reply #169 on: 09/12/2018 05:35 PM »
The President and Chief Operating Officer of SpaceX said 5-10km offshore.  She wouldn't have said that unless SpaceX had analyzed all aspects of the offshore pad at those distances, including sound.

In the absence of any information, speculation is fine. It's part of what makes this a great forum.

But when we have it straight from the horse's mouth, speculation otherwise seems pointless.

For example, many of us here speculated that BFR specs from horses mouth at IAC 2016 would change.  They did. 
When far off plans meet reality, especially when they are not engineering constrained, but regulatory, they have an even greater risk of change. 
SpaceX statements are not stone tablets to be worshiped without question, but current plans subject to change over the many years before possible fruition.  I had thought SpaceX was notable for its ability to change course on the fly to adapt to reality intrusions and opportunities previously unknown or not sufficiently vetted.  I doubt that BFR P2P is sufficiently vetted as of 2017.

I had speculated that P2P would be no closer than 16Km from shore because of noise, etc.
As predicted, an updated "spec" from Gwynne.
Reddit: "We'll land on our own platform that's out at sea. Largely because cities probably won't want something hovering over their billion dollar buildings. It's also very loud. (Notably sonic booms.) Will land in international waters."

International waters can't be closer than ~22Km.

« Last Edit: 09/12/2018 05:38 PM by philw1776 »
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