Author Topic: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)  (Read 108105 times)

Online jongoff

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #20 on: 09/29/2017 02:56 PM »
From the previous thread:

Quote
I mean, sure he's LOX/CH4 which isn't well matched with the Moon.

I'll keep correcting this because people keep getting it wrong. There is plenty of CO2 (and CO, even methane and hydrogen) in lunar polar ice (see it mentioned in a peer-reviewed journal here or here). If you are going to do ISRU for fuel on the Moon, its going to be polar ice deposits, and this it going to be useful regardless whether your engine eats methane or hydrogen.

I just wanted to comment on this so it doesn't enter into the conventional wisdom unchallenged, but as I've discussed elsewhere (http://forum.nasaspaceflight.com/index.php?topic=39559.msg1612453#msg1612453), there's reason to suspect the CO2/CO/Methane results that got mentioned in the popular press. As Spudis points out, the sensor that they actually have more experience with showed almost all of the volatiles as water, it was the one that they weren't as familiar with that showed the anomalously high CO/CO2 numbers. Be careful, this area isn't as set in stone as quoting peer reviewed journals makes it seem.

~Jon

Edit: modified a few times to add back in the links, and the link to the original thread, for continuity sake.
« Last Edit: 09/29/2017 03:03 PM by jongoff »

Offline Norm38

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #21 on: 09/29/2017 03:03 PM »
On the last thread I saw some minor complaints that Elon didn't show us anything really new, that we didn't already know or hadn't already deduced from rumors.  But I think what is more instructive is what he didn't talk about.  Things that people have been fixating on and we can now ignore.

What will SpaceX NOT be doing?

No reusable upper stage for F9  -  No resources for it.
No Raptor upper stage for FH  -  No resources for it.
No Raptor version of F9 (4-6m)  -  Not in architecture.
No Launch Escape System      -  Not in architecture.
No sci-fi propulsion elements  -  Not in architecture.
No spaceship SSTO                -  Not in architecture.

Let's focus on what they say they ARE doing.

« Last Edit: 09/29/2017 03:18 PM by Norm38 »

Offline speedevil

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #22 on: 09/29/2017 03:08 PM »
What will SpaceX NOT be doing?

No reusable upper stage for F9  -  No resources for it.

As a test platform with some elements of BFR, this seems unclear.

Aimed at a full up landing capable reusable stage, perhaps not.

Offline TrevorMonty

When comes to moon SpaceX are transport company, somebody else has to own and build base.

While BFR may lower transport costs considerably. It doesn't lower build costs of lunar habitats designed for lunar enviroment.





Offline Garrett

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #24 on: 09/29/2017 03:15 PM »
What I don't get is why they haven't yet proposed using the BFR itself as an LEO Space Station (e.g. as a successor to the ISS). It will be capable of spending long durations in space, so it seems perfectly suited for this.

For example, one could have two BFR's set up for orbital space station activites. They would then alternate going up and down to orbit (say, every 6 months or so). When a ship is on the ground, it could be fitted out with the next set of experiments. Then, it would launch with a full crew and cargo for the 6 months, so no need for visiting vehicles during that time (so less microgravity perturbations). Also, no need for EVA's for repairs. After the 6 months, it would return and the second vehicle would take its place, and so on. So, basically like the Shuttle Orbiter/Spacelab, with much more volume, more crew (12-ish say) and the capability to stay on orbit for long periods of time.

Obviously, experiments requiring longer durations would need another orbiting platform, but there's plenty of room in LEO!

Kind of a waste of a vehicle that can be launched with very little turn around. How many flights does it miss out on in 6 months? Lots of lost revenue.

Three BFR cargo flights can put a space station as big as ISS in orbit. Drop off a 150 ton space station in a single flight.
It's not to be compared with a transport system. It's a completely different use, where the cost savings are elsewhere than rapid turn around. It would be a science and technology platform used by governments and private enterprises.
The cost savings come from (non-exhaustive list):
 - less overhead for maintaining orbiting space station. The current ISS requires massive manpower (thousands of people, can't find an exact figure).
 - EVA's are dangerous and expensive. A BFR that goes up and down should require no EVA's
 - no visiting vehicles (more cost - materials, manpower, etc)
 - no need for experimenters to design expensive "robust" space experiments that need to last years. Breakdowns can be fixed and modifications added on later rotations.

I honestly think that the whole notion of a permanent LEO outpost is a bit outdated with the likes of a reusable BFR available.
- "Nothing shocks me. I'm a scientist." - Indiana Jones

Offline RonM

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #25 on: 09/29/2017 03:16 PM »
When comes to moon SpaceX are transport company, somebody else has to own and build base.

While BFR may lower transport costs considerably. It doesn't lower build costs of lunar habitats designed for lunar enviroment.

Yes, but transportation costs are the biggest barrier. Maybe ESA can afford the moon village concept if SpaceX can deliver the cargo and crew.

Offline obi-wan

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #26 on: 09/29/2017 03:18 PM »
A friend who works on Falcon 9 in Hawthorne told me last month that they were all "looking forward to moving onto BFR in a couple of years." Evidently, this talk (and Elon's timeline) was also a surprise to the working-level troops at SpaceX.

Offline RonM

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #27 on: 09/29/2017 03:19 PM »
What I don't get is why they haven't yet proposed using the BFR itself as an LEO Space Station (e.g. as a successor to the ISS). It will be capable of spending long durations in space, so it seems perfectly suited for this.

For example, one could have two BFR's set up for orbital space station activites. They would then alternate going up and down to orbit (say, every 6 months or so). When a ship is on the ground, it could be fitted out with the next set of experiments. Then, it would launch with a full crew and cargo for the 6 months, so no need for visiting vehicles during that time (so less microgravity perturbations). Also, no need for EVA's for repairs. After the 6 months, it would return and the second vehicle would take its place, and so on. So, basically like the Shuttle Orbiter/Spacelab, with much more volume, more crew (12-ish say) and the capability to stay on orbit for long periods of time.

Obviously, experiments requiring longer durations would need another orbiting platform, but there's plenty of room in LEO!

Kind of a waste of a vehicle that can be launched with very little turn around. How many flights does it miss out on in 6 months? Lots of lost revenue.

Three BFR cargo flights can put a space station as big as ISS in orbit. Drop off a 150 ton space station in a single flight.
It's not to be compared with a transport system. It's a completely different use, where the cost savings are elsewhere than rapid turn around. It would be a science and technology platform used by governments and private enterprises.
The cost savings come from (non-exhaustive list):
 - less overhead for maintaining orbiting space station. The current ISS requires massive manpower (thousands of people, can't find an exact figure).
 - EVA's are dangerous and expensive. A BFR that goes up and down should require no EVA's
 - no visiting vehicles (more cost - materials, manpower, etc)
 - no need for experimenters to design expensive "robust" space experiments that need to last years. Breakdowns can be fixed and modifications added on later rotations.

I honestly think that the whole notion of a permanent LEO outpost is a bit outdated with the likes of a reusable BFR available.

Everything you list can be done with a 150 ton station dropped off by a cargo BFR. No need to use a BFR as the station.

Offline ZachF

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #28 on: 09/29/2017 03:22 PM »
It looks like the lower engine configuration will probably look something like this:

Offline jpo234

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #29 on: 09/29/2017 03:25 PM »
A friend who works on Falcon 9 in Hawthorne told me last month that they were all "looking forward to moving onto BFR in a couple of years." Evidently, this talk (and Elon's timeline) was also a surprise to the working-level troops at SpaceX.

Depends on the definition of "a couple of years". BFR is obviously not ready right now and they need to build enough Falcons for next year and then start the stockpiling.
2018 and 2019 will probably still see the Falcon line open. I can't imagine that they are able to shut the line down before 2020. 2 years might qualify as a "couple"...
You want to be inspired by things. You want to wake up in the morning and think the future is going to be great. That's what being a spacefaring civilization is all about. It's about believing in the future and believing the future will be better than the past. And I can't think of anything more exciting than being out there among the stars.

Offline Jakusb

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #30 on: 09/29/2017 03:26 PM »
So transportation as well as launching should become relatively much less of a problem once they get BFS actually working and landing back on earth...
Build factory somewhere convenient and launch from there to actual launch site somewhere on the globe...
Launch site best Factory only needs to take care of not flying over populated area. Can be anywhere as it does not have to take into account optimal position for certain orbital slots.
I am pretty sure this is how they realized that it could as easily be used for commercial transport across the globe. ;)

Damn, if they get this to work, the options seem plenty and amazing.

Offline Endeavour_01

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #31 on: 09/29/2017 03:27 PM »
Two of the many things I found exciting about this presentation were the ideas of the BFS/BFR servicing ISS and launching a large space telescope.

Timeline wise I am not sure ISS servicing will happen (will ISS get extended beyond 2024, SpaceX time dilation factor) but that picture of the BFS (with wings!) docked to the ISS was a thing of beauty.

In the render of the BFS deploying a satellite it seems like that particular BFS has a "cargo pod" payload configuration vs. the "crew" payload configuration. It seems SpaceX will also use the tanker version of BFS as a cargo only system, which makes a lot of sense.
I cheer for both NASA and commercial space. For SLS, Orion, Falcon 9, Falcon Heavy, Dragon, Starliner, Cygnus and all the rest!
I was blessed to see the launch of Space Shuttle Endeavour on STS-99. The launch was beyond amazing. My 8-year old mind was blown. I remember the noise and seeing the exhaust pour out of the shuttle as it lifted off. I remember staring and watching it soar while it was visible in the clear blue sky. It was one of the greatest moments of my life and I will never forget it.

Offline Johnnyhinbos

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #32 on: 09/29/2017 03:30 PM »
If 2022 was the target for the first two cargo versions of the BFS, then I would expect some pretty amazing test launches and landings of both the BFR and BFS in 2020 or 2021...
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Offline NWade

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #33 on: 09/29/2017 03:37 PM »
Looking at the Moon Base still image (at 32:39 on the YouTube video), is anyone else concerned about the width of the landing legs with respect to heavy cargo being mounted ~70% up from the bottom of the vehicle and being cantilevered out with a crane (beyond the leg/foot area)?
 
I get that the cargo will be offloaded in small loads, but I wonder about stability - especially if you don't land on a dead-flat surface (there are very few grading machines on the Moon or Mars at present).
 
--Noel
 
« Last Edit: 09/29/2017 03:37 PM by NWade »

Offline AncientU

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #34 on: 09/29/2017 03:37 PM »
When comes to moon SpaceX are transport company, somebody else has to own and build base.

While BFR may lower transport costs considerably. It doesn't lower build costs of lunar habitats designed for lunar enviroment.

It does if you don't have to make them bleeding-edge light weight. 
Also eliminates separate landers (likely expendable), both development costs and hardware costs.
Eliminates a DSG... on-orbit refueling, limited crew size, etc.
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Offline Ronsmytheiii

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #35 on: 09/29/2017 03:39 PM »
Timeline wise I am not sure ISS servicing will happen (will ISS get extended beyond 2024, SpaceX time dilation factor) but that picture of the BFS (with wings!) docked to the ISS was a thing of beauty.

Well if BFR is really as cheap per launch as Elon advertised, might be fiscally possible to return Hubble..... I hope SpaceX does this!
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Offline titusou

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #36 on: 09/29/2017 03:40 PM »
Well... :)

Titus

---
Redo to fix a tiny bug :)
---
Edit to fix another typo
« Last Edit: 09/30/2017 03:24 PM by titusou »

Offline oldAtlas_Eguy

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #37 on: 09/29/2017 03:41 PM »
One item not elaborated upon is: is there a difference between the cargo variant and the tanker variant?

There is definitely a difference between the cargo variant and the manned variant.

The cargo variant may see early heavy usage if SpaceX truly develops and deploys its LEO comm constellation. A single launch would deploy ~ 256 sats (400kg each of 380kg plus 20 kg of launcher per sat that stays in cargo bay) which will fill 4 orbital planes of same inclination. It would take 17 launches to deploy the full ~4,400 sats. The cargo would return the empty dispenser for reuse.

Offline Khadgars

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #38 on: 09/29/2017 03:48 PM »
Being uncritical of schedules for the moment.


2022, two cargo vehicles landed on Mars means launch June 2022 (how do the orbital mechanics stack up?)
What does this mean as a minimum?

It means the booster and tanker have accumulated 40 or so flights in order to refuel the vehicles.
It means they have launched ~2000 tons of cargo (fuel) to orbit.
Landing has been extremely well proven on earth, and on mars.

It probably means that individual boosters have a demonstrated flying reliability.

All this at the same time EM1 and EM2 are supposed to launch, for a billion per launch, rather than a million.

Loved the presentation and where SpaceX is heading, BFR is really exciting.  However, I'd add at least 10 years to the schedule IMO.  So starting in 2032 we'd get first launch to Mars and 2034 first crewed (which happens to match up with NASA own plans).

Offline Prettz

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Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 2 (Post Speech)
« Reply #39 on: 09/29/2017 03:50 PM »
Elon mentioned buidling a stock pile of Falcon 9 and Falcon Heavys for customers before buulding nothing but BFR. Where could he store all of these stages?
Hopefully not all in the same place. In Florida they could all be taken out by a hurricane. In California they could all be taken out by an earthquake.

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