SpaceX 2018 Lunar Flyby

Void · 2017-03-03 09:56:29

Well that's generous help.

From what I see, if an economical lander could be built, then it is more likely that an activity justified by economics and science can be sustained.

I think the Apollo LEM is not needed, because with a light lander without a cabin/airlocks, you could:
1) Do short stop missions of hours.
2) Transport humans and consumables to habitats on the Moon, if there are any.

While I am thinking of an "Basket Design" for transporting humans and some supplies, I would think a sky crane concept might make sense for dropping loads on the Moon, if that sky crane could be of multiple usage. The sky crane would not need landing legs, which would reduce weight. It would simply drop it's load and fly back to orbit, and be refueled.

I don't know if such a sky crane would then be returned to Earth Orbit/Earth. I think that more likely it would be used until failure dropping loads from lunar orbit to the surface and flying back to orbit. When it failed, a new one would replace it.

A trial balloon I guess.

Last edited by Void (2017-03-03 10:00:53)

GW Johnson · 2017-03-03 10:53:00

What news stories there are about this tourist moon flight are rather devoid of hard factual information. But, the consensus of what I have seen is a simple lunar flyby and free return, no capture into lunar orbit.

With a crew of only 2, with associated supplies, Falcon Heavy should be able to easily fling a not-max-weight crewed Dragon on that trajectory. That leaves the Super Draco propellant supply untouched except for attitude control with the little Dracos.

No one is talking at all about the landing. But with most of the propellant unused, the design powered landing on land is feasible. Whether they want to do that "up front" is not known; there's risk because it hasn't yet been done with a Dragon. If it were me, I would do some unmanned test landings that way before I risked it with people.

GW

Oldfart1939 · 2017-03-03 15:04:03

There has been an announcement that there will be an unmanned version carried out before the manned flight. Can't remember which of the space websites reported this but it was a quote from Elon Musk.

Oops! The comment was there will be retro-propulsive landings done in advance of the mission.

Last edited by Oldfart1939 (2017-03-03 15:47:30)

Terraformer · 2017-03-03 15:49:49

Aren't you thinking of the Mars mission? There's no plan to land on Luna, at the moment.

GW Johnson · 2017-03-03 16:28:48

Oldfart1939:

That's good news. At least they are trying to do it right.

Terraformer:

Nope. Not Mars. Not NASA either. This is Spacex sending two paying tourists around the moon, per the very recent announcements. Their announcement said 2018.

Everybody:

My approximations to delta-vee requirements for worst-case orbital configurations (but Hohmann transfer nonetheless) show only a small fraction of a km/s difference to fling something to Mars or to the moon, directly launched from the surface of the Earth with "typical" gravity and drag losses. Both are 12-something km/s launcher capability, and both leave nothing for maneuver, orbit, or landing at destination.

Spacex does not list moon payload capability on its website for Falcon-Heavy, but they do show 13.6 metric tons flung to Mars. Looks to me like they're just about the same.

My best approximations to a weight statement for crewed Dragon show a max load configuration between 11 and 12 metric tons. The announced mission would be with two aboard, plus supplies for something like 8-10 days for the free return. I saw nothing to indicate there would be a third aboard as a pilot, just automatic controls backed up by ground controls.

GW

Last edited by GW Johnson (2017-03-03 16:31:44)

Void · 2017-03-04 09:09:49

GW Johnson. As always, your abilities are very valuable. Yes if we look at the title "SpaceX Lunar Flyby", we could presume that this topic is only about that one mission.

However in Post#1 by Terraformer it was stated:
Quote:

I feel this needs it's own thread.
SpaceX press release.
Only a flyby, but hopefully (!) the harbinger of things to come.

I guess that that is subject to interpretation. However in the title the term Lunar exists along with Flyby.
Terraformer said:

Only a flyby, but hopefully (!) the harbinger of things to come.

So, I guess he could speak for himself on what he thinks are things to come.

In post #19 Louis introduced this:
Quote:

I've been banging the drum for lunar tourism for a number of years here. I think it's very doable and there is a market worth billions of dollars among the planet's super-rich. I think Musk has spotted the potential to generated huge revenue and fund his Mars project.

So now since lunar tourism, and huge revenue were introduced, I responded to that drift.

And I responded in my posts #24 and #26. Raising some topics which mostly stay in compliance with existing and possible SpaceX hardware, as was requested by Spacenut in his post #3:
Quote:

To keep the topic tightly constrained we must only talk to the content in the article which will only be a space x hardware only mission unlike the other Apollo 8 redux topic.

Very well, I will stay with real and potential SpaceX hardware, which could also include landers contracted out by SpaceX, if it did not want to directly get into the landing business.

As for the money, I learn from Louis who has shown thinking in the past that tourism, and universities, and other science establishment, both national and private, could contribute to the funding of such missions.

You have shown that perhaps SpaceX could land some of it's hardware on the Moon.
I guess if they want to avoid development costs and not be diverted, they could do that, or to my thinking it would make more sense to build landers that are specifically designed for the Moon.
They could build them or rent/buy them from some other specialty outfit, just like they build/buy parts.

It is not for me to say, but I don't think that any such minor Moon program should be done with the battle star galactica mentality. No pressurized LEM's with airlocks. Just people in spacesuits traveling from orbit <>surface, and likewise materials moved Orbit<>Surface.

For those two classes of transfers, I suggest an open bucket-cage travel device for humans and some cargo, and later, perhaps skycrane type propulsion to mostly drop materials to the surface.

Skycranes would not land at all. They would drop their load, and head back to orbit, to be refurbished/refueled as many times as is economically and technologically possible.

The open basket method would either be for very short stops on the surface, or to deliver persons Orbit <> Habitats on the surface.

The skycrane would be to set up bases, or put scientific automated equipment onto the surface.

Per my posts #24 and #26, this is better described.

Last edited by Void (2017-03-04 09:33:22)

Oldfart1939 · 2017-03-04 09:27:31

Some of the numbers I've seen published state the spacecraft will have a maximum distance of 400,000 miles from Earth before the inexorable forces of gravity take over and bring it back to the surface. What an unimaginable view they will have of the Moon silhouetted against the Earth? Probably the most fantastic "tourist trip" ever conceived?

Void · 2017-03-04 09:34:20

It's a great starter. Since nobody mentioned landing, that must be me.

So nobody surely likes it.

Last edited by Void (2017-03-04 09:39:53)

GW Johnson · 2017-03-04 09:58:29

I think it was in another thread here in the "human missions" group where I addressed getting into lunar orbit with existing Spacex hardware (Falcon-Heavy flinging crew Dragon). It's very hard to tell, and it's a close thing with no margins, but I think the second stage would have enough propellant left to get into lunar orbit with a lightly-loaded crew Dragon.

[edit 3-4-17: it was in post 15 above in this very thread that I mentioned getting crew Dragon into lunar orbit at reduced weight.]

There's barely enough delta-vee in a lightly-loaded crew Dragon's Super Draco/Draco system to get back out of lunar orbit (~0.8 km/s). That forces parachute-only landings at sea. I rather doubt they really want to do that, precisely because it's risky without an alternate for landing. They really do need a service module for crew Dragon, or at least a trunk with extra propellants for the thrusters and a way to connect them.

Once that service module or extra propellant is in place, they would have the capability to reprise Apollo-8 style lunar orbit missions with crews, and without the light-load limitations they have now. I'm going to hazard the guess that this is something they are working on, but have not yet announced publicly. It just makes too much sense for them not to be looking at it

From there, you use a second rocket to shoot unmanned a lunar lander to lunar orbit, then shoot the men there to go rendezvous with it. At that point, they can reprise the Apollo 11 type missions, as long as the lander falls in the same 12 ton class of flung weight that crew Dragon does. That lander would need something like a total 3.4 to 3.5 km/s minimum delta vee capability to get from lunar orbit to the surface and back again.

GW

Last edited by GW Johnson (2017-03-04 10:07:36)

Void · 2017-03-04 10:04:10

Nice. It all depends on where the money could be, I would think that even though Elon Musk is focused on Mars as his ultimate goal, we know that he has many other interests. If he can use his hardware to make money from Moon activities, I cannot imagine he would not.

Terraformer · 2017-03-04 11:17:44

My guess is that any reprisal of Apollo 11 would involve sending the lander separately and an orbital rendezvous, using a modified Dragon that can enter and leave Lunar orbit. If they start work on the latter soon (I know, I know, they've yet to launch a manned Dragon), and if someone else develops a lander in the next couple of years...?

Perhaps we could send people to visit Tranquility base by July 20th, 2019.

Oldfart1939 · 2017-03-04 14:06:32

GW-
An interesting concept would require use of another component in the system: the Russian-built Proton M 3rd stage. Here are the details:

Type: Storable Propellant Stage

Inert Mass: 4,185 kg

Diameter: 4.14 meters

Length: 6.5 meters

Propellant: UDMH

Oxidizer: NTO

Fuel & Ox: 46,562 kg

Total thrust:613.8kN

Burn time: 238 seconds

Isp(vac): 325 seconds

My suggested model incorporates the Falcon 2 + Trunk, + dry Proton M 3rd stage to ~20,000kg, including upgraded onboard fuel for retro propulsive landing on Earth. I'm figuring on a delta V around 3.5 km/sec for the rocket equation. This gives a mass ratio of ~ 3.0.

If we configure the Dragon 2 for a crew of 4, with onboard supplies for food, an atmosphere purifier, no water recycling at 11,000 kg, adding tankage and additional fuel over and above the "normal" 1900 kg at 3,800 kg (total fuel = 5,700 kg), the empty mass of the Proton M 3rd stage at 4,185 kg, and a trunk with a motor at 1500 kg, we get a payload mass of 20,485 kg. Fully fueled, this results in a total "wet" rocket mass of 67,047 kg with a mass ratio of 3.27. This implies there will be fuel remaining after departure for insertion into Lunar orbit. The increased fuel for the Dragon capsule also implies sufficient fuel for de-orbit burn and adequate fuel for dry land propulsive landing.

This is not the calculation of a sophisticated aerospace engineer, just an amateur. Please make comments! This requires orbital assembly and 2 loads to LEO. The mass of the Proton M 3rd stage is well within the capability of the Falcon Heavy.

Last edited by Oldfart1939 (2017-03-04 14:10:31)

SpaceNut · 2017-03-04 21:14:32

Now you all see why we are having trouble keeping topics organize with a scope of discusion an ther is so much out of the box comments.

The trouble with a progress stage is the coupling of them does not match up as the core of the falcon is 3.7 m in diameter which now means interstage coupling collars are need to make an off the shelf work at all.

The again it is just a small thing as even an extended stage from Space x would also need a interstage coupling collar to mate the stages together for such a flight to occur thou these would be simpler as they already make use of them. I am sure with modifications to those that we would have a better match up of the sections to build the lunar rockets components up at the ISS.

Space x can only move so fast with all the changes that are needed in order to progress what they have to being able to do the flyby and then to proceed to being able to create something to think about landing with.

If I were the other rocket launch companies out there I would be looking to build up from what they have a rocket capable of the same feat. This is what speers on competition as its availability to provide at a cost of affordability that we need.

Oldfart1939 · 2017-03-05 09:31:54

The main problem here is having 2 closely related threads going at the same time: Apollo 8 Redux, along with the present one. So...I plead "Guilty" for somewhat mixing and confusing the topics, since one mission is strictly a Fly-By, a simple loop flown around the Moon, whereas the other, Apollo 8 Redux, requires entering circumlunar orbit. My mission architecture was postulation of how the Fly-By could be modified into the Circumlunar Orbit variety.

GW Johnson · 2017-03-05 17:36:17

Referring to my post 34 just above, I ran my estimated weight statements and performance for crewed Dragon with extra propellant tanks installed in its trunk, staying within the 3000 kg published trunk cargo limit. I put 2800 kg extra propellants contained in 147 kg of tank inerts in that trunk, and just 2 suited crew plus 500 kg samples and supplies in the capsule. It weighs just a smidge over 12 metric tons as flung by its booster.

That extra tankage is a 95-5 split on propellant vs tank to contain it. Some sort of link between trunk propellant and what the Super Dracos can use is implied, but I suspect that's plumbing hardware around 5-10 kg or less, so I ignored that, as being well within my weight statement uncertainties.

It's capsule-plus-trunk delta-vee that is of interest here, since the electricity comes from solar cells mounted on the trunk skin, in crewed Dragon. You'll need that for the trip from the moon back to Earth, jettisoning the trunk right before Earth entry interface.

My results under those assumptions show a total capsule-plus-trunk delta-vee capability of 1.6 km/s. That's enough to cover 0.8 km/s to get from lunar orbit into a return trajectory, some significant midcourse and attitude control, plus (after trunk jettison and entry) something like 0.5+ km/s for a propulsive landing on land back on Earth. Maybe a big +.

The total mass for crewed Dragon rigged like this was just over 12 metric tons. Spacex says its Falcon-Heavy can fling 13.6 tons to Mars, although they do not specify what trajectory. For a min-energy Hohmann transfer ellipse, and 5% gravity and drag losses on the first 8 km/s, I show a trajectory to Mars as at least 12.1 km/s. I show (under the same 5% losses) a delivery into lunar orbit as no more than 12.4 km/s. Those correspond to the factored theoretical delta-vees, the factored ones being the ones that set your mass ratios for your designs.

12.2 tons vs 13.6 tons. 12.4 km/s vs 12.1 km/s. Looks to me like Falcon-Heavy can deliver a 12.2 ton crewed Dragon to lunar orbit, from which it can return, if rigged with 2800 kg extra propellant in the trunk. That's a crew of 2 in suits with 500 kg of samples and supplies. Add a third crewman with suit and supplies, and you start pushing toward 13 tons.

GW

Oldfart1939 · 2017-03-05 18:17:39

GW-

If this is simply a reprisal of Apollo 8, and not a landing; knock off the 500 kg for samples. That could be another crew member, or simply a larger margin of safety (additional fuel/oxidizer).

SpaceNut · 2017-03-05 21:00:35

Like apollo there is no way back once half way to the moon so it will need to be able to get back on the free return...
I think the launch is also a direct course with no circulization as well.

Will copy post #37 & 38 to the Apollo 8 Redux and the apollo 11 redux as well

GW Johnson · 2017-03-06 11:59:42

It's pretty clear that Spacex can conduct a manned lunar flyby with the "existing" crew Dragon and Falcon-Heavy, just as soon as these have flown enough to demonstrate that they work correctly. That's actually a better standard of "man-rating" than what NASA did before flying men on a Saturn 5 for Apollo 8. My guess is that the crews of such flyby missions could be larger than two, if such opportunity for paying passengers presented itself.

What I tried to show by calculation is that a minimal modification to the crew Dragon configuration should enable its use into lunar orbit, instead of just a flyby. That modification is adding significant extra propellant capacity into the crew Dragon trunk, and connecting it for direct use in the Super Draco/Draco pods on the capsule.

There's enough "oomph" in the Falcon-Heavy flown all-expendibly to fling a crewed Dragon massing roughly 12 metric tons into lunar orbit, using a final burn of the second stage to get there. The extra propellant in the Dragon trunk gets you back out of lunar orbit onto a trajectory home, with more than enough left for midcourses, attitude control, and powered landing on land.

My calculations are based on too many assumptions to be entirely correct, but I am showing most of the weight added to the Dragon that brings it near to 12 metric tons is the propellant needed for the lunar orbit departure: I added 2800 kg in 147 kg of tankage to the trunk, pushing its published 3000 kg cargo limit pretty hard. The capsule was lightly loaded at 850 kg total, for 2 suited crew plus 500 kg of supplies, etc.

Whether there is volume for this propellant in the trunk, I don't know and did not try to investigate. But trunks can be lengthened: there already is one available for cargo Dragon. Spacex's website shows it.

What I like about my concept is two "ways out" if the second stage final burn into lunar orbit should fail. (1) do nothing, make the flyby instead, and just return home. (2) If deemed crucial enough to take the risk, separate from the stage, make the orbit entry burn with the Super Dracos, and use them to get back out of lunar orbit to come home. Worst-case that's two 0.8 km/s burns for the capsule-plus-trunk, which has a smidge over 1.6 km/s capability with the extra 2800 kg propellants in the trunk.

That second is a risky option, leaving little budget for attitude control with the Dracos, and no budget for powered landing, thus forcing a ocean landing with the chutes. But it does seem to be a feasible choice, and a second way out.

I looked at this not just for reprising Apollo-8, but also because you could resume minimal moon landings with a lunar orbit-capable Dragon, combined with a separately-launched lunar lander, that they rendezvous with in lunar orbit. So, what I have been figuring applies to Apollo-11 reprises as well.

I think some others have already been looking at lunar lander configurations. If it masses about 12 tons at ignition, Falcon-Heavy could fling it to lunar orbit unmanned. If it's bigger, you either fling it with a bigger rocket, or you do on-orbit assembly and fueling in Earth orbit.

New Glenn is a ways off, and SLS is going to be very expensive and hard to get, when it does begin flying in a year or two. Falcon-Heavy and crew Dragon should start flying this year. I'd suggest doing orbital assembly and fueling, if you cannot stay within the limits of a Falcon-Heavy to lunar orbit (I'm guessing 13 metric tons max). Our old Apollo LM was about 15-16 tons.

Perhaps these threads should be combined into one. Just a thought.

GW

Last edited by GW Johnson (2017-03-06 12:12:19)

Void · 2017-03-06 12:52:07

GW Johnson,

Normally I avoid threads like this. However I have followed your thinking and wanted to communicate the existence of a different possible "Wrinkle" in this that could change things a bit.

https://www.washingtonpost.com/news/the … 3a8f19e6f6

Mr. Big! Ha Ha:

Robert Bigelow, the founder of Bigelow Aerospace, a maker of inflatable space habitats, said his company could create a depot that could orbit the moon by 2020, housing supplies and medial facilities, as well as humans. A smaller version of the possible habitats, known as the BEAM, is docked to the International Space Station, where astronauts have been testing it.
In an interview, Bigelow said he was glad the administration seems to be refocusing on the moon. “Mars is premature at this time. The moon is not,” he said. “We have the technology. We have the ability, and the potential for a terrific business case.”

Mr. Bezos:

The Blue Moon spacecraft could carry as much as 10,000 pounds of material and fly atop several different rockets, including NASA’s Space Launch System, the United Launch Alliance’s Atlas V or its own New Glenn rocket, which is under development and expected to fly by the end of the decade, the company said.
“Once on the surface, the lander’s useful payload can be used to conduct science or deploy rovers,” the company said. “A robotic arm attached to the lander will deploy to examine the lunar surface with an array of instruments.”

So, for the concept of space tourism for the Moon, how hard is it to see an alliance between NASA, Elon Musk, Jeff Bezos, and Mr. Big. That could allow a massive expansion to the Moon and then Mars?

If Jeff Bezos can deliver to Mr. Bigelow's orbital station instead of to the Lunar surface at first, then Elon Musk can indeed go beyond fly by activities, and then stop to orbit the Moon. Resupply from Mr. Big, with supply's from Jeff Bezos. Then eventually short term landings.

This is going to be a rough moment:
https://www.bing.com/news/search?q=Peop … &FORM=EWRE

I don't actually approve of people being overly silly about taking risk and dying, but we also have a problem where the death of any person in space could cause a psychotic insanity.

We know that space is dangerous. I advise against foolishness as per risk for life. But we are going to have to get beyond the news media psychotic moment. We hope to never have a dead person. But any sane person knows it is going to happen eventually on the Moon. Especially if rich Brits are sent to the Moon.

Lets compare to the Mt. Everest thing:
https://en.wikipedia.org/wiki/List_of_p … nt_Everest
Yes, because it is there. Well, lets at least give them a chance to do something meaningful.

I guess, I am thinking ya, lets work on sane, but lets not also be the kid that is afraid of going into the deep end of the pool. Handled correctly that kid will figure out how to deal with it most likely. But everybody dies (So far).

I am going to be a happy guy, if NASA, Alon Musk, Jeff Bezos, and Mr. Big get into the same strategic plan with each of their techniques.

Last edited by Void (2017-03-06 13:21:49)

Oldfart1939 · 2017-03-06 14:03:49

I happen to disagree that Mars is premature at this time. In contrast to the Moon, Mars has some resources which may be exploited with less energy and uncertainty. I particularly like the diurnal cycle of Mars a lot better, as well as reduced exposure to damaging radiation via the thin but measureable atmosphere. Mr. Big is laying out a sales pitch...

GW Johnson · 2017-03-06 16:59:38

Relative to my post 43 just above, I compiled and posted what I did reverse-engineering what the variants of Dragon could do. This is posted as an article dated 3-6-17 entitled "Reverse-Engineered "Dragon" Data". The site is my "exrocketman" blog site http://exrocketman.blogspot.com.

I agree with Oldfart1939: Mars is not premature at this time. We have known everything we need since the mid 1990's, and we have had far cheaper launch rockets for almost a decade now.

As for putting a Bigelow inflatable around the moon, well, why not? B330 lists as 20 tons, not within what Falcon-Heavy can deliver to lunar orbit, using the second stage to enter that orbit. But a smaller version at 12 tons could be.

SLS could do that B330 20 ton thing to lunar orbit. Atlas-5 cannot. Delta-4 cannot. Falcon-Heavy cannot quite. Nor can Falcon-9. How big a station you want? B330's dock together. Reduced-size modules could, too.

Refuel in Earth orbit, and Falcon-Heavy could do the job, even with a full-size B330.

GW

SpaceNut · 2017-03-06 19:57:07

Bigelow's inflateable does not have the protection required for staying a lunar orbit.

Many thanks for the "Reverse-Engineered "Dragon" Data" that you have done as its quite something to work things backwards to prove out if a concept is possible....

Void · 2017-03-06 20:33:19

Spacenut said:

Bigelow's inflateable does not have the protection required for staying a lunar orbit.

Whats the problem? I would like to understand.

SpaceNut · 2017-03-06 21:37:40

The Bigelow Expandable Activity Module (BEAM) is an experimental expandable space station module which will be used to determine the levels of radiation protection capability of inflatable structures. Hopefully they will provide a degree of protection from solar and cosmic radiation, space debris, atomic oxygen, ultraviolet radiation and other elements of the space environment. But thats inside the protective megasphere of earth and not in deep space or circling the moon.

Void · 2017-03-07 00:08:11

Didn't like your answer. Goodby.

Last edited by Void (2017-03-07 01:37:22)

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#26 2017-03-03 09:56:29

Re: SpaceX 2018 Lunar Flyby

#27 2017-03-03 10:53:00

Re: SpaceX 2018 Lunar Flyby

#28 2017-03-03 15:04:03

Re: SpaceX 2018 Lunar Flyby

#29 2017-03-03 15:49:49

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#30 2017-03-03 16:28:48

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#31 2017-03-04 09:09:49

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#32 2017-03-04 09:27:31

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#33 2017-03-04 09:34:20

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#34 2017-03-04 09:58:29

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#35 2017-03-04 10:04:10

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#36 2017-03-04 11:17:44

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#37 2017-03-04 14:06:32

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#38 2017-03-04 21:14:32

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#39 2017-03-05 09:31:54

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#40 2017-03-05 17:36:17

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#41 2017-03-05 18:17:39

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#42 2017-03-05 21:00:35

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#43 2017-03-06 11:59:42

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#44 2017-03-06 12:52:07

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#45 2017-03-06 14:03:49

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#46 2017-03-06 16:59:38

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#47 2017-03-06 19:57:07

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#48 2017-03-06 20:33:19

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#49 2017-03-06 21:37:40

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#50 2017-03-07 00:08:11

Re: SpaceX 2018 Lunar Flyby

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