Author Topic: SpaceX Crewed Dragon Circumlunar Mission  (Read 504479 times)

Offline jongoff

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #440 on: 02/28/2017 09:45 pm »
I understand that what they are planning is just to fly around the moon and not enter lunar orbit.

I would love to know in terms of fuel requirements, once you reach the moon how much additional fuel would be needed for orbit insertion and then escape lunar orbit and head back to earth.

If it takes X amount of fuel to do TLI, how much more would be needed for lunar orbit? are we talking about 20% more, 50% more, double? etc.

Just Curious.

TY

As a rough rule of thumb, using storable propellants:

One kilogram on a translunar trajectory takes 4 kg in low Earth orbit
One kg in lunar orbit takes 4 kg in translunar trajectory
One kg on the lunar surface takes 4 kg in lunar orbit
One kg returned to Earth takes 4 kg on the lunar surface

Not suitable for use in navigation, but it supplies a good intuitive bound to the problem.

I'm not sure how legit those rules of thumb are...

The key Delta-V numbers are approximately:

LEO to TLI -- ~3100m/s
TLI to LOI -- ~800m/s
LUNO to EOI -- ~800m/s

So, if you wanted a Dragon capsule to enter low lunar orbit from a Trans Lunar Injection orbit, and then subsequently do an Earth return burn that would take it back to earth, you're talking on the order of 1600m/s or so.  Assuming a 320s Isp for NTO/MMH, that yields a required mass ratio of MR=e^(dV/(Isp*g0))=1.67. That means that if you had a 10mT capsule (I can't remember the Dragon V2 numbers off the top of my head), you'd need to send an additional 6.7mT of prop through TLI for it to enter and exit lunar orbit.

That's enough that you almost certainly couldn't do it with a FH, but not multiple 4x multipliers.

Also, that was for entering a circular LLO. If you want to enter/exit EML-2 it's more like 150-250m/s each for entry and exit if you do a powered lunar swingby on the way out and back. That would only require ~1.7mT of extra propellant, which might actually be feasible. But it would make your trip *much* longer (on the order of 3wks). So you'd likely need to beef up the ECLSS non-trivially compared to an ISS capsule. Still intriguing though--I could see a future Dragon V2 option to deliver crews/passengers/cargo to an EML-2 station.

~Jon

Offline kraisee

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #441 on: 02/28/2017 09:54 pm »
How can anyone, other than a member of congress, support SLS and Orion at their costs? 

Its the same old two edged sword that we faced on DIRECT.

SLS has become a money pit of a program, but the decision makers for that program are exactly the same ones who are the core supporters of NASA within Congress, and they are the only line of defense against the other members of Congress who would prefer to gut the whole agency budget for other programs of their choice.

Don't forget that NASA's top line budget is also set by these same people (think: which leading appropriator represents NASA rocket design center in Alabama?   Always follow the money).

Then we must also remember that these same people are chosen by the electorate in their own states specifically to look out for the interests of the people in that state.   So it isn't much of a surprise that they push programs that create jobs in those districts.   That's their actual job.

So, the choice sadly comes down to supporting the expensive SLS program and the rest of NASA in tow, or remove the core political support for the agency and see the whole of NASA's budget gutted - and that would include gutting SpaceX's contracts and the science budget too.

You don't have to like it - I don't - but the choice comes down to putting up with SLS, or cutting everyone's budget.   Pinching my nose, I'll continue to 'support' SLS.

Ross.
« Last Edit: 02/28/2017 09:57 pm by kraisee »
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Offline ChrisWilson68

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #442 on: 02/28/2017 10:04 pm »
The timing of this announcement is all about the customer.  Someone agreed to pay for the trip, no more, no less.

The timing of the announcement is very calculated. Elon has too prominent a seat at the new administration's table for it not to be.

There's zero evidence for that, and it makes little sense.  Elon said two people put a significant deposit down for a flight around the Moon.  Do you think he was lying?  If so, the lie will eventually be exposed.  Elon isn't dumb enough to do that.  If he wasn't lying, this isn't something Elon just dreamed up, it's based on an external factor: these two people who paid money.  Do you think they put down a deposit long ago and Elon has been sitting on that news just waiting until he can use the announcement for political purposes?  That doesn't make any sense to me.  He wouldn't know if there would eventually be a time to announce it for political purposes, and in the meantime SpaceX would be failing to capitalize on this great PR.

Offline MATTBLAK

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #443 on: 02/28/2017 10:22 pm »
...And it's really nice to hear from Ross again - our NSF Blood-Brother. Your post is succinct and one I pretty much concur with.
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Offline dglow

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #444 on: 02/28/2017 10:26 pm »
The timing of this announcement is all about the customer.  Someone agreed to pay for the trip, no more, no less.

The timing of the announcement is very calculated. Elon has too prominent a seat at the new administration's table for it not to be.

There's zero evidence for that, and it makes little sense.  Elon said two people put a significant deposit down for a flight around the Moon.  Do you think he was lying?  If so, the lie will eventually be exposed.  Elon isn't dumb enough to do that.  If he wasn't lying, this isn't something Elon just dreamed up, it's based on an external factor: these two people who paid money.  Do you think they put down a deposit long ago and Elon has been sitting on that news just waiting until he can use the announcement for political purposes?  That doesn't make any sense to me.  He wouldn't know if there would eventually be a time to announce it for political purposes, and in the meantime SpaceX would be failing to capitalize on this great PR.

Whoa. Please take a breath and read what I wrote. In no way do I suggest Elon is lying.

Your opinion: the timing is all about the customer. Mine: the timing is very calculated.

Quote
Do you think they put down a deposit long ago and Elon has been sitting on that news just waiting until he can use the announcement for political purposes?

It appears Elon did not make his announcement as soon as the deposit was made. Read what Bergin wrote:

"A NASA HQ source claimed they were not informed about the announcement ahead of Elon’s comments on Monday, although he believes Acting Administrator Robert Lightfoot and President Trump’s NASA “Landing Team” was briefed, which in turn – the source claimed – was why Mr. Lightfoot asked NASA to conduct a study into accelerating the schedule towards crewed missions on Orion."

Quote
He wouldn't know if there would eventually be a time to announce it for political purposes, and in the meantime SpaceX would be failing to capitalize on this great PR.

The evidence we have suggests otherwise. Musk didn't announce until after NASA made the EM-1 study public. He did announce in advance of Trump's speech tonight. Let's wait and see whether there's any connection there.

Peace.

Offline meekGee

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #445 on: 02/28/2017 10:33 pm »
Of course, but the gist of it remains. The old launch vehicles can't escape the reality of what's happening.  You can only bury your hand in the sand and keep ploughing along (A physical impossibility, I know, but doesn't seem to stop people) for so long.

The F9/FH/D2 architecture is about the stabilize now, at a performance level that is even above what was originally promised.

With Block 5 and streamlined barge operations, SpaceX will be launching at a cost point that's just without competition and will be servicing markets that it created - from comsat constellations to tourism - that they created.

Which now really puts it out there - what is NASA (or anyone else) doing developing expendables?  And is there any place for them in a reusable market that has SpaceX, and at some point BO?

NASA should at this point really do some soul searching.  It's got plenty of places to go, but trying to stay in the launcher game isn't one of them.

I think transportation-level ideas (e.g. depots) will be best handled by the launch providers.  But there's a lot of science that can be done with fund that can be liberated from SLS.  More science probes.  More planetary science.  More telescope platforms.  More basic science and technology.  Please.
« Last Edit: 03/01/2017 12:19 am by Chris Bergin »
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Offline envy887

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #446 on: 02/28/2017 10:48 pm »
...
I think transportation-level ideas (e.g. depots) will be best handled by the launch providers.  But there's a lot of science that can be done with fund that can be liberated from SLS.  More science probes.  More planetary science.  More telescope platforms.  More basic science and technology.  Please.

I doubt any funds liberated from SLS will go to NASA.

Offline ChrisWilson68

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #447 on: 02/28/2017 10:59 pm »
How can anyone, other than a member of congress, support SLS and Orion at their costs? 

Its the same old two edged sword that we faced on DIRECT.

SLS has become a money pit of a program, but the decision makers for that program are exactly the same ones who are the core supporters of NASA within Congress, and they are the only line of defense against the other members of Congress who would prefer to gut the whole agency budget for other programs of their choice.

Don't forget that NASA's top line budget is also set by these same people (think: which leading appropriator represents NASA rocket design center in Alabama?   Always follow the money).

Then we must also remember that these same people are chosen by the electorate in their own states specifically to look out for the interests of the people in that state.   So it isn't much of a surprise that they push programs that create jobs in those districts.   That's their actual job.

So, the choice sadly comes down to supporting the expensive SLS program and the rest of NASA in tow, or remove the core political support for the agency and see the whole of NASA's budget gutted - and that would include gutting SpaceX's contracts and the science budget too.

You don't have to like it - I don't - but the choice comes down to putting up with SLS, or cutting everyone's budget.   Pinching my nose, I'll continue to 'support' SLS.

Ross.

I've heard that claim before.  I have yet to see any convincing evidence that it's true.

Offline ChrisWilson68

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #448 on: 02/28/2017 11:10 pm »
The timing of this announcement is all about the customer.  Someone agreed to pay for the trip, no more, no less.

The timing of the announcement is very calculated. Elon has too prominent a seat at the new administration's table for it not to be.

There's zero evidence for that, and it makes little sense.  Elon said two people put a significant deposit down for a flight around the Moon.  Do you think he was lying?  If so, the lie will eventually be exposed.  Elon isn't dumb enough to do that.  If he wasn't lying, this isn't something Elon just dreamed up, it's based on an external factor: these two people who paid money.  Do you think they put down a deposit long ago and Elon has been sitting on that news just waiting until he can use the announcement for political purposes?  That doesn't make any sense to me.  He wouldn't know if there would eventually be a time to announce it for political purposes, and in the meantime SpaceX would be failing to capitalize on this great PR.

Whoa. Please take a breath and read what I wrote. In no way do I suggest Elon is lying.

Yeah, that's my point.  Obviously, he's not lying, and I figured you didn't think so either.  So I wanted to dispense with that possibility first.

Your opinion: the timing is all about the customer. Mine: the timing is very calculated.

Quote
Do you think they put down a deposit long ago and Elon has been sitting on that news just waiting until he can use the announcement for political purposes?

It appears Elon did not make his announcement as soon as the deposit was made. Read what Bergin wrote:

"A NASA HQ source claimed they were not informed about the announcement ahead of Elon’s comments on Monday, although he believes Acting Administrator Robert Lightfoot and President Trump’s NASA “Landing Team” was briefed, which in turn – the source claimed – was why Mr. Lightfoot asked NASA to conduct a study into accelerating the schedule towards crewed missions on Orion."

Yeah, and I've discussed that exact quote from the article in other posts.

Two important points here:

1. This is from a NASA source and he says NASA wasn't briefed.  And it says the source "believes" there was a briefing.  It's not clear whether the source actually has any information for that believe or whether it's pure speculation.

2. Even if Trump's team was briefed, that doesn't mean the announcement was timed for political purposes.  For example, Musk might have made the deal 3 weeks ago and decided to do an announcement, then briefed the White House, then did the announcement.  The timing is still based on being done a short time after the deal was done.

Quote
He wouldn't know if there would eventually be a time to announce it for political purposes, and in the meantime SpaceX would be failing to capitalize on this great PR.

The evidence we have suggests otherwise. Musk didn't announce until after NASA made the EM-1 study public. He did announce in advance of Trump's speech tonight. Let's wait and see whether there's any connection there.

You still haven't given any evidence.  The timing of Musk's announcement relative to the EM-1 announcement could be coincidence.  Or the EM-1 announcement could have been rushed to come before Musk's announcement, which the the opposite of the causal relationship you're claiming.  Or the EM-1 announcement might have triggered the customers to do the deal with Musk.  There are all kinds of possibilities.  The truth is we just don't know.

Offline yg1968

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #449 on: 02/28/2017 11:13 pm »
How can anyone, other than a member of congress, support SLS and Orion at their costs? 

Its the same old two edged sword that we faced on DIRECT.

SLS has become a money pit of a program, but the decision makers for that program are exactly the same ones who are the core supporters of NASA within Congress, and they are the only line of defense against the other members of Congress who would prefer to gut the whole agency budget for other programs of their choice.

Don't forget that NASA's top line budget is also set by these same people (think: which leading appropriator represents NASA rocket design center in Alabama?   Always follow the money).

Then we must also remember that these same people are chosen by the electorate in their own states specifically to look out for the interests of the people in that state.   So it isn't much of a surprise that they push programs that create jobs in those districts.   That's their actual job.

So, the choice sadly comes down to supporting the expensive SLS program and the rest of NASA in tow, or remove the core political support for the agency and see the whole of NASA's budget gutted - and that would include gutting SpaceX's contracts and the science budget too.

You don't have to like it - I don't - but the choice comes down to putting up with SLS, or cutting everyone's budget.   Pinching my nose, I'll continue to 'support' SLS.

Ross.

You could find substitute government projects: Mars habitats and a lander come to mind. It's not like we are on the verge of running out of things to spend on for Mars exploration or colonization.

Offline Coastal Ron

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #450 on: 02/28/2017 11:18 pm »
So, the choice sadly comes down to supporting the expensive SLS program and the rest of NASA in tow, or remove the core political support for the agency and see the whole of NASA's budget gutted - and that would include gutting SpaceX's contracts and the science budget too.

You don't have to like it - I don't - but the choice comes down to putting up with SLS, or cutting everyone's budget.   Pinching my nose, I'll continue to 'support' SLS.

NASA is not monolithic, and the SLS and Orion only support the "Human Exploration Operations" part of the budget, which includes the ISS and Commercial Cargo & Crew.

Cancelling the SLS and Orion won't affect the ISS or Commercial Cargo & Crew, and certainly won't affect the Science, Space Technology or Aeronautics Research parts of NASA.  And it may not "free up" any money for any of those either, which is OK by me.

NASA is a tool that the U.S. Government chooses to solve non-defense related specific problems that deal with space (not so much aeronautics anymore unfortunately).  And if we don't have a problem that the SLS and Orion solve, then we don't need them - and funding them "just because" would be a drain on NASA's overall resources, and a waste of taxpayer money.

This SpaceX mission is showing that we may have reached an inflection point in history where the technology has come down enough in overall price that private individuals can afford to not only leave Earth, but travel just as far as government employees have.  And the government is not involved in a direct way.

One of the goals of our government is to support the private sector, and if our government wants to support private sector space-related activities then we might have reached a point in our history where NASA doesn't need to own as much infrastructure as they had to own at the beginning of the space era, and instead they can rely on the private sector for their needs.  That should be celebrated, not feared.

So in that light this mission by SpaceX to send two civilians around the Moon is definitely historic.  Whereas the SLS and Orion EM-1 proposed mission is looking more and more like a desperate attempt to salvage two programs that were never needed from Day 1.
If we don't continuously lower the cost to access space, how are we ever going to afford to expand humanity out into space?

Offline oldAtlas_Eguy

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #451 on: 02/28/2017 11:53 pm »
My take is that with a selected Lunar orbit that the Dragon2 on FH can reach and return, possibly refueling at the docking location to be able to return, presents two methods of Lunar orbit "providers" that would support a deep space habitat. Now add using the EM-1 flight to launch a BE-330DS instead of a one off Orion mission and then accelerating the EM2 mission to be able to then be able to have regular 6 month stays on the DS Lunar station starting in 2021.

This would be my hope for the direction things go. If not then another provider needs to develop DS capability with their CC system. Meanwhile SLS/Orion disappears and is replaced with the public /private program for DS Lunar habitat and transport of crew and cargo as an outgrowth of the CC program. A BTW Vulcan using ACES with distributed launch can reach and actually possibly exceed any of the FH and even SLS payload capabilities.

As far as whether there is an Lunar orbit that the Dragon2/FH can reach is unknown because the basis to determine that is not a public set of information containing the exact design details of both the FH and the Dragon2.

As far as whether upper level government managers knew about this mission and why it was just announced is that negotiations are not an instant thing and take in some case multiple months. The public announcment would be after the negotiations have concluded and a contract existed. The upper level government managers could have been briefed that SpaceX had been contacted by customers that would like to hire such a ride at SpaceX soonest opportunity and SpaceX started negotiations with these customers. They would also possibly breifed of when that soonest possibility could be.

Offline speedevil

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #452 on: 03/01/2017 12:10 am »
As a rough rule of thumb, using storable propellants:

One kilogram on a translunar trajectory takes 4 kg in low Earth orbit
One kg in lunar orbit takes 4 kg in translunar trajectory
One kg on the lunar surface takes 4 kg in lunar orbit
One kg returned to Earth takes 4 kg on the lunar surface

Not suitable for use in navigation, but it supplies a good intuitive bound to the problem.

Is anyone aware of a thread for 'existing spacex hardware' mini lander?
Something along the lines of a gimballed Draco thruster, 50kg of propellant, and a 20kg payload, to be kicked out of the trunk sometime before the moon, get to a safe distance and then enable. It would be very hard to get something that lasted over a lunar day.
The Yutu rover weight 140kg. https://en.wikipedia.org/wiki/Yutu_%28rover%29

Offline virnin

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #453 on: 03/01/2017 12:15 am »
Just wondering when this new mission will show up on the SpaceX Launch Manifest web page.  Maybe they're still trying to decide on a title for it?

Offline docmordrid

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #454 on: 03/01/2017 12:25 am »
Red Dragon = Mars

Silver Dragon = Moon? (lyric: Light of the Silvery Moon)
DM

Offline dglow

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #455 on: 03/01/2017 12:41 am »
You still haven't given any evidence.  The timing of Musk's announcement relative to the EM-1 announcement could be coincidence.  Or the EM-1 announcement could have been rushed to come before Musk's announcement, which the the opposite of the causal relationship you're claiming.  Or the EM-1 announcement might have triggered the customers to do the deal with Musk.  There are all kinds of possibilities.  The truth is we just don't know.

That's right, we don't know.

All we have is Thiel in the administration, a sudden announcement by Musk, Bergin's source in NASA, and Yang and Berger's tweets about tonight. A lot of smoke. No point arguing whether or not we see flames.

FWIW, I want Musk to be calculating in these matters. For the sake of SpaceX, I hope he is political. It's a good and necessary thing, IMO.

Offline vt_hokie

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #456 on: 03/01/2017 12:49 am »

This SpaceX mission is showing that we may have reached an inflection point in history where the technology has come down enough in overall price that private individuals can afford to not only leave Earth, but travel just as far as government employees have.  And the government is not involved in a direct way.


Well, yes and no.  SpaceX is using technology developed largely though government efforts, refined and improved to reduce costs but not revolutionary, and arguably Falcon 9 and certainly Dragon wouldn't exist without NASA funding. 

I'm excited by this announcement, because it seems realistic enough to have a real shot of happening (even if 2018 is a little optimistic) and to see people leave low Earth orbit for the first time in my life, having been born too late for Apollo, would be nothing short of awesome.  So, I'm all for it provided that it does not threaten commercial crew in any way (which I suppose it shouldn't, as long as proper resources are devoted to that, and as long as a failure of this risky flight doesn't also risk lengthy delays in commercial crew).
« Last Edit: 03/01/2017 01:36 am by vt_hokie »

Offline meekGee

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #457 on: 03/01/2017 12:50 am »
Just wondering when this new mission will show up on the SpaceX Launch Manifest web page.  Maybe they're still trying to decide on a title for it?

Kardashian Dragon? 

I mean, if you're gonna pay for it, maybe you get to name it?

(no, not for realz)
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Offline Jdeshetler

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #458 on: 03/01/2017 01:19 am »
Silicon Dragon?
 
- Silicon is the 2nd most common elements on the lunar surface.
- Those 2 deep pocket riders may be related to Silicon Valley in a way.

Offline maitri982

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Re: SpaceX Crewed Circumlunar Mission - 2018
« Reply #459 on: 03/01/2017 02:24 am »
I think SLS will be cancelled.  It's a waste of money given the new commercial alternatives coming online.

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