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SpaceX Mars / Re: SpaceX tanker variant
« Last post by Norm38 on Today at 08:34 PM »
There's a lot more widely accessible oxygen on the moon bound up in rocks than either carbon or hydrogen.  So in a far future where lunar LOX was supplying an orbital fuel depot, there may be a need to truck only methane. But that's a long ways off.

I know the title of this thread is tanker variant but given Musk's descriptions, I would not be surprised if the tanker was the first to fly.  Given how it would be stripped down, lowest cost, less to lose in case of mishap, I'd try to fly the tanker first, and then make the full BFS the variant of that.
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Why is everybody taking ACES as a given?

For the same reason people take Falcon Heavy as a given. Or the SLS, or Vulcan. Because they within the scope of what's reasonably possible. But I think everyone also knows that funding, politics or other things can change direction, so until they fly we're still crossing our fingers for our favorite hardware programs...  :)

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ULA timelines have very clearly and consistently stated, that the very first flight of ACES is expected "as early as" 2023 - which we all know is code for "yeah, but it's going to slip".

I'm a SpaceX supporter, and it's the same for Falcon Heavy. FH has not been a priority for SpaceX, just as ACES has not been a priority for ULA, so the dates for when they would become operational have always been sort of undefined until an actual need forces a date. That has happened for FH, but ULA is still searching for customers for ACES - which this proposal would create.


But SpaceX never announced launching 3 Falcon Heavies for a customer one year before the scheduled maiden flight Falcon Heavy. Inmarsat ended up launching on an expendable Falcon 9 and the flight around the moon was announced for a date more than a year *after* the first flight of Falcon Heavy.

Plus, plans for ACES haven't changed. Tory Bruno just retweeted this a few minutes ago: https://twitter.com/WeAreGoFL/status/920684164202057729 And I'm very sure he would have pointed out a recent change in schedule, if there was one. Instead there are now plans of an enlarged Centaur stage. In fact, he is on record (back in 2015) saying that it is likely going to be operational in the 2024/25 timeframe. https://twitter.com/torybruno/status/625994038697676800

ACES is very ambitious in a number of ways, lots of things that haven't been done before and need testing. Yet, we are still waiting for ULA to so much as choose an engine for it. It's not a generic stage that just needs to get done. It's new technology that takes time to develop and it's also not worth focussing the entire company on developing it, just to get that one payload into space by 2022. It makes absolutely no economic sense and the company just isn't doing it either. So why announce it? Why say "This lunar depot could be deployed easily by 2022"?

Even Elon Musk makes it clear where his time frames are extremely optimistic - and those are about Mars settlements, not business engagements.
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A space hotel? ... If you were going in BFS, you might as well just stay in the BFS?

LLO in a BFS, with those windows (and 100 of your closest friends) for less than $1million each (SWAG). That would be a tourist flight!

Sorry off topic *hides under duvet from mods*
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Historical Spaceflight / Re: Happy 49th Anniversary Apollo 7
« Last post by MarsMethanogen on Today at 08:27 PM »
To be really picky, it's the S-IVB stage -- the S-IV was the six-RL-10-engine second stage of the Saturn I.
My omission.  Not picky at all and absolutely correct.
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This sure looks like an acceleration to me. A constantly changing acceleration.

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How is this in any way relevant?

I'm sorry, I thought it was obvious. It's an acceleration isn't it? You said any acceleration, so I replied with the wave behavior of the superposition of two waves of different amplitude. This is analogous to what's happening in a resonator with asymmetric losses.
It is an acceleration if you are talking about a physical resonator, such as waves on a string, but not if you are talking about one where it is something like electromagnetic fields that are doing the oscillating.

Going with the waves on a string, so that you are talking about something where acceleration applies, then yes, there is acceleration, so as I said, there will be relativistic time dilation from the accelerations, but they obviously would be miniscule for most physical systems.  (And yes oscillating EM fields would originate from oscillating charges, and those charges therefore accelerate and would experience time dilation)

Again, what relevance does this example of an acceleration have to the point that spupeng7's and dustinthewind's descriptions are not compatible with known effects?

I see you expanded your question. I'm not supporting spupeng7 or dusty's descriptions, I'm supporting and developing my own. I disagree with your first sentence. Why do you think this only applies to things like waves on a string? Why the arbitrary line? Are you drawing the line because of mass? Thanks.
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More of this conversation.

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Jacob Aron
@jjaron
Replying to @jeff_foust
How else you going to solve it? In a turf war on an ESA launch site, seems like the ESA mission wins

@jeff_foust

I think we would have heard otherwise—particularly from members of Congress unhappy to spend NASA money to help an ESA mission.

https://mobile.twitter.com/jeff_foust/status/920722875375652869
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There's also this https://arxiv.org/abs/1505.01646

--- Tony
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General Discussion / Current Cost of Launches
« Last post by Bundolo on Today at 08:11 PM »
I'm wondering what the cost is to launch a freight capsule is the ISS.  By cost I mean the cost that the company would charge an outside agency to launch the craft which would be provided.  Which entitiy is the least expensive?   
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Spaceflight Entertainment and Hobbies / Re: Star Trek Discovery
« Last post by Star One on Today at 08:09 PM »
I don't think we're in violent disagreement here. I'll keep watching Discovery, but I'm not totally hooked by it. One of my issues with it is that the main characters (Michael, Lorca) are less interesting to me than some of the others. I'm more interested in Saru and, believe it or not, Tilly.*

My biggest overall issues with the show, however, are:

-it just looks too different from previous Star Trek, particularly the Klingons, but other things as well
-it lacks the optimistic tone I've come to associate with Star Trek
-it's a bit too dark and humorless, and I wish they would lighten up a bit



*Her comment that she had a secret, that she was going to be a captain someday, was rather intriguing. I heard her say that and I thought "Now that's a story I'd like to see."

It’s a bit early to judge though after just five episodes, I am not even sure Lorca is going to last the season.
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The recent NROL-76(?) on SpaceX was a SpaceX launch procured by the vehicle provider, Ball. I would assume this is a similar scenario. As the govt tries to bring costs down the procurement approach for satellites now makes the contractor also procure the launch service, forcing them to decide between ULA or SpaceX. The government also likes this because if it blows up, then the prime has to bear the responsibility for it, not the govt.


I'd bet money this was not a last minute contract. It was likely included in whatever contract the govt agency signed with NG for the satellite. Satellites don't get built last minute.
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