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#76 2018-01-14 12:39:06

Void
Member
Registered: 2011-12-29
Posts: 3,011

Re: Alternate BFR (Big Falcon Rocket)

I do note your post Terraformer.

Spacenut, I have noted your posts.  With enormous pleasure I note the ballistic capture has now be accepted as a topic.  Previously Elderflower began to talk about external tanks.  So, little by little we progress.

The only remaining item that I tried to introduce is personal radiation armor.
We can see if that can arrive eventually.

But that brings us to the central point of all of this, the health of a crew, if you are going to have a crewed mission.

And a crewed mission has extra cost.  Both in money and health.

Alright, lets have at the fuel issue.  The entire emphasis of Elon Musk and SpaceX is that it is the hardware that is expensive, not the fuel.  In order to make space activities more possible the emphasis has been on making some hardware more reusable.  I think I understand why Elon Musk and SpaceX want the BFR to be completely reusable.  It is kind of a good moral behavior.  However, Falcon 9 is not totally reusable, not the upper stage, not even the faring yet.  (They are working on the faring).

And we can expect occasional first stage failures on launch and landing, but they are getting really good at it apparently.

And sometimes they actually sacrifice a 1st stage of Falcon 9 if the load that needs to be lifted is worth it. 

So reusability is a desire and can have cost benefits it seems, but it is not absolutely mandated for all situations.

So now, we have extra tools in our tool box.  We can have expendable external fuel tanks, or somewhat re-usable external fuel tanks.  Depending on what it is that needs to be accomplished, and how much worth the accomplishment has.

Our cost is always balanced against the value of what it accomplishes.

Why not simply rely on internal fuel tanks?  Well, they have to be moved up and down from orbit, and they have significant constraints on size and shape.  External fuel tanks offer a significant liberalization of those constraints.  And where it is profitable they can be disposed of or re-used as cost and purpose dictates.  Extending the capabilities of the human race.

Back to ballistic capture smile

To be fair to myself, I only know what I read on the internet, and of course we know that everything presented on the internet could be sometimes a bit of B.S.

But lacking alternatives I have to run with what I can get, and what I can get is, that in certain situations you can have fuel savings with ballistic capture.  You have already modified that to restrict it to using a ion rocket.  Actually I don't care that much.  As I have already indicated above, due to the fuel rich environment that BFR is advertised to create, I am not that worried about fuel savings.

It appears from what I read, that ballistic capture has two time issues.
1) It takes longer, by months, which from our point of view is bad.
2) You can initiate it almost anytime, which from out point of view should be wonderful.
*(This would be a gigantic benefit if it is true.  Then there would be a much shorter mission time in low gravity and exposed to radiation and other dangers).

That means you might be able to get in and accomplish your mission and get out asap, and get back to Earth without the typical degree of health penalties on the crew for having spent time in low gravity.  Also it reduces the radiation exposure.

And further if you do have external tanks around your BFR and are more propellant rich, you have more radiation protection from that as well.

So the benefits exist.

But I am not done.

It appears that for ballistic capture you can either go to an aeroburn or not.  You could come back to Earth without an aeroburn, if I understand the situation.  A weakened crew might benefit from this.  They could be transferred to a fully fueled BFR in Earth orbit with doctors and such with medical equipment to assist them.  They could be brought down to the surface of Earth relatively gently, and with the assistance of such medical provisions.

So, I will see how many holes the members can shoot in all of this.  From my view of reality at this time it makes sense, but I reserve the right to be wrong.  I just don't see how I am wrong at this point.

I'm done Spacenut, commence firing!

Last edited by Void (2018-01-14 13:14:25)


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#77 2018-01-14 13:23:49

SpaceNut
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Posts: 16,557

Re: Alternate BFR (Big Falcon Rocket)

Going slow for the use of Ballistic capture aka gravitational capture must use as a requirement artificial gravity and radiation shielding for human crews no if's no and's or but's to it.....

The external tanks can be shipped to mars by ion drive slow but with that they need to be a storeable fuel as oldfart1939 has said for the purpose of orbit as well as surface preload for later use. Later switching over to other fuels as insitu manufacturing allows.

Personal radiation armor is what we are in need of for surface exploration to be assumed as the shelter has it built into it.
Others here have said to lug heavy objects are for the exercise on the surface to keep fit so if using the same type of shielding for xray tech is all that is required for shielding then that works for both issues.

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#78 2018-01-14 13:57:06

Void
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Re: Alternate BFR (Big Falcon Rocket)

Quote:

Going slow for the use of Ballistic capture aka gravitational capture must use as a requirement artificial gravity and radiation shielding for human crews no if's no and's or but's to it.....

No actually.  A mission where you went to Mars, by Hohmann transfer method or Ballistic Capture, might allow you to hang out and do whatever you intended to do, and then come back asap using Ballistic Capture method and the luxury of abundant propellants.

Quote:

The external tanks can be shipped to mars by ion drive slow but with that they need to be a storeable fuel as oldfart1939 has said for the purpose of orbit as well as surface preload for later use. Later switching over to other fuels as insitu manufacturing allows.

Excellent!  I did not want to bring that up for fear of causing frustrated anger, but I love that option as well!  Lets put it in the tool box!

Quote:

Others here have said to lug heavy objects are for the exercise on the surface to keep fit so if using the same type of shielding for xray tech is all that is required for shielding then that works for both issues.

https://en.wikipedia.org/wiki/Stormtrooper_(Star_Wars)
With apologies to star wars fans, I think this is a stupid looking outfit, but of course they are the bad guys.
330px-Romics_2013_135.JPG

My view is to make the exoskeleton primarily out of Paraffin wax or something like that with perhaps a cloth surface.

And yes, excellent idea to try to incorporate it into a Mars suit.  But for it's value, why not bring them with the crew to use during microgravity travel.

As I have stated before, the health of the crew is very important.  Cancer is very bad.  Loss of brain function is also very bad.

I'm done.  Going to lunch and the Gym.  Will be gone for a while.

Last edited by Void (2018-01-14 14:10:13)


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#79 2018-01-14 14:19:54

Oldfart1939
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Registered: 2016-11-26
Posts: 1,764

Re: Alternate BFR (Big Falcon Rocket)

Void-

The external fuel tank option was actually hidden in my proposal of shipping fully fueled "modules" to Mars orbit. Using an ion propulsion unit would be ideal for these. I then propose mating these "fuel modules" with propulsion units attached to the Earth return vehicles. So yeah, I'm proposing a lander/ascender stage which would be left in Mars orbit upon return to Earth. Yes, there is a lot of orbital assembly involved, but nobody said this would be a piece of cake to accomplish. Maybe--just maybe--we should consider building a von Braun "bicycle wheel" space station in Mars orbit so there would be a chance of getting some gravitational reconditioning prior to a Mars landing? And before a return Hohmann transfer ballistic orbit back to Earth?

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#80 2018-01-14 15:17:06

SpaceNut
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Re: Alternate BFR (Big Falcon Rocket)

Δv to enter Hohmann orbit from Earth's orbit (km/s) 2.9, Δv exiting LEO 11.3, Δv from LEO 3.6
The delta-v needed is only 3.6 km/s, only about 0.4 km/s more than needed to escape Earth, even though this results in the spacecraft going 2.9 km/s faster than the Earth as it heads off for Mars.

http://www.instructables.com/id/Calcula … -Transfer/

https://www.jpl.nasa.gov/edu/teach/acti … h-windows/

https://en.wikipedia.org/wiki/Gravity_of_Mars The average gravitational acceleration on Mars is 3.72076 ms−2 and it varies laterally Seasonally.

With ballistic capture, on the other hand, the spacecraft launches ahead of its target. The craft takes its time—and less fuel—slowing down to some speed that's less than the speed at which the target orbits the sun. Eventually, the target catches up to the craft and sucks it into orbit around itself using its own gravitational pull.

tons of equations

https://www.space.com/30749-the-martian … -mars.html

The Hohmann alignment only happens once every 26 months. Mars and the Earth are not in a good alignment, and it will take 414 days which is the wait plust time out for a rescue on the martian movie.

Using the ballistic capture transfer, the resupply spacecraft could have left as soon as NASA realized Watney was alive, with a flight time of about 294 days, taking 234 days to reach a point on Mars' orbit. From there, it would need another two months to get to Mars itself using a ballistic capture transfer. The flight time would have been 294 days — a savings of 120 days, giving Watney a much better chance of survival.

https://www.reddit.com/r/spacex/comment … igeekicks/

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#81 2018-01-14 15:28:06

RobertDyck
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Re: Alternate BFR (Big Falcon Rocket)

Terraformer wrote:

You need to bring a lot less fuel if you leave your return ship in orbit and use a shuttle to reach it from Mars, compared to landing your ERV. It's what they did with Apollo.

As GW has said, if ISRU works out on that mission you can use it to visit a lot more sites. If it doesn't, then they'll have to wait.

You realize that's the basis for my changes to Mars Direct.

Oldfart1939 wrote:

The long-term definitely needs production of methane via the Sabatier reaction, but for a first few missions--I suspect not. I suggested the Aerozine 50 or MMH, or UDMH as the most energy-dense fuels available
...
The scale of the BFR really DOES require some prior "boots on the ground," just to pave the way for the future. The "pioneers" need to (1) find the water, (2) set up all the power generation facilities, and (3) start methane production in a MONITORED fashion. Then, and only then, will the BFR become reality.

I think we're in general agreement. The only issue is ISPP reduces launch mass for the first mission. That's important to keep cost down. Old Space and those in NASA supporting them want to maximize cost, so much so that nothing has happened. As long as they have their way, nothing will happen. Ever. Elon is trying to bypass them, and we all applaud his effort. However, we need something before BFR. I argue to leave the ERV in Mars orbit. That eliminates propellant needed to land it on Mars, but more importantly eliminates propellant needed to lift it off again. It also enables a reusable ITV, from Earth orbit to Mars orbit and back. And my architecture means astronauts ride with the ERV, so if a free return is necessary they have with them all food for the Mars stay plus all food for the Earth return. This provides more redundancy than Mars Direct. But for the first mission, I want to produce all propellant for return via ISPP. Not only return from Mars Orbit, but propellant for ascent from the surface. Use the MAV as the TEI stage. Bring hydrogen for the first mission means we aren't dependant on Mars ice. But again, we don't want to bring return propellant, because that drastically increases launch mass, which increases mission cost.

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#82 2018-01-14 19:49:50

Void
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Posts: 3,011

Re: Alternate BFR (Big Falcon Rocket)

I am pretty happy with what has been proposed this day by the various.  Not necessarily because my plan is the one blessed.  On the contrary, I would like us to plan at least two Alternate BFR's.

Mine and yours.  I do hope you would innovate to achieve the goals of Elon Musk in an improved way.

At the same time my plan is to trap the scientific community into an alternate plan and to screw over the B.S. people who don't even want the human race to rise above captivity.  (They also pretend that their intentions are moral in some way)  They use whatever argument that they can to capture the energy of the movement and divert it to stupid purposes.  At least that is how I see it.

So, go ahead, if you can manage to get onto Mars, and nobody stops you for the bio-issues, then OK.

If a booger monster migrates from Mars to Earth and eats us all then OK, I'm kind of old anyway.  That will save me from being killed by the robot rebellion.

smile


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#83 2018-01-14 23:33:20

Oldfart1939
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Registered: 2016-11-26
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Re: Alternate BFR (Big Falcon Rocket)

The chances of the bio issue doing anything other than causing an allergic reaction are pretty slim unless we've had a common biological precursor with an amino acid and nucleic acid based biology. And unless the foreign amino acids are also Levorotatory with corresponding Dextrorotatory carbohydrates, the standard forms of disease organisms wouldn't be able to "eat and propagate."

Last edited by Oldfart1939 (2018-01-15 09:10:55)

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#84 2018-01-15 04:38:33

elderflower
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Registered: 2016-06-19
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Re: Alternate BFR (Big Falcon Rocket)

I would be very surprised if Mars life (if any) were to have different stereochemistry from Earth life. Virtually all earth life uses only one hand of stereo isomers. That could be due to some fundamental property of stuff which we haven't worked out yet, in which case all life everywhere would follow the same rule, or it could be due to the exceedingly low probability of life arising at all so that it only happened once in all of earth's history. In the latter case, any life found in the solar system would have been spread by meteorites from wherever it occurred in the first place, rather than occurring multiple times in different places. Earth is quite favourable to life and if it were to arise de nouveau more than once it should have done so here.

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#85 2018-01-15 08:21:52

RobertDyck
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Re: Alternate BFR (Big Falcon Rocket)

elderflower wrote:

I would be very surprised if Mars life (if any) were to have different stereochemistry from Earth life. ... Earth is quite favourable to life and if it were to arise de nouveau more than once it should have done so here.

Maybe it did. Earth has had many mass extinction events. And some scientists have pointed out that bacteria have the ability to travel through the vacuum of space, and survive. Life doesn't gain an ability unless it has a reason. A random mutation will exist in a very small proportion of the population unless something selects for survival, causing it to spread through the population. These same scientists pointed out life began on Earth as soon as conditions were favourable. This raises the suspicion that life arose before the planetary collision that created the Moon. After geologists studied Moon rocks, they concluded that a planet about the size of Mars collided with Earth. Most of that other planet was absorbed, making Earth that much larger. Much of the crust of the Earth, and some of the crust of other planet, was thrown into space. That formed a ring which quickly coalesced to form our Moon. If you can call 10 million years "quickly". The Moon formed much closer than it is today, causing extreme tides. The surface of the Earth was molten magma for a long time. Any life on Earth would have been destroyed by that lava and magma. Some rocks rained back down. Those who believe "re-seeding" theory, believe ancient bacteria or archaea rode on those rocks. The ones that fell into a lake of lava were destroyed. Rocks that fell on solid ground, survived. Any organism that couldn't survive a trip through space, didn't. Those that could, did. According to this theory, all life today descends from that "re-seeding" event. So any life that had different stereochemistry would have died.

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#86 2018-01-15 09:18:08

Oldfart1939
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Re: Alternate BFR (Big Falcon Rocket)

What Robert has described in post #85 is generally referred to as "Panspermia." This suggests that life was brought to Earth by cometary impacts and seeding via intergalactic life-bearing dust. It also implies that there is a universal chirality to the basic chemicals of life; i.e. L-amino acids and D-carbohydrates.

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#87 2018-01-15 11:13:40

louis
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Re: Alternate BFR (Big Falcon Rocket)

I think panspermia is a lot more credible now than say 50 years ago, given what we now know.

The existence of extremophiles is also quite suggestive of panspermia.  Evolution is normally not lavish in its endowments - it works to the parameters, so it's a bit of a puzzle why extremophiles are able to cope with conditions far more demanding than exist on Earth.

Last edited by louis (2018-01-15 11:15:19)


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#88 2018-01-15 11:34:59

Oldfart1939
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Re: Alternate BFR (Big Falcon Rocket)

The more or less "accepted" hypothesis for the abundance of water on Earth is through early cometary impacts. If comets bring water, they should also be vehicles for the panspermia life forms. An indicator for this is the supposed abundance of PAH in comets. (PAH = Polynuclear Aromatic Hydrocarbons). But until we get a real sample of the core of a comet, there's just no telling...

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#89 2018-01-15 11:51:06

elderflower
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Re: Alternate BFR (Big Falcon Rocket)

If there is any Mars life we probably share a common origin and our immune systems will probably deal with it. Given a few months return trip, Hoffman style (not Gerard I hope) astronauts will have had a reasonable quarantine on the way back. Its not the moderately intelligent bags of wet bacteria that need to worry.

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#90 2018-01-15 13:06:09

RobertDyck
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Re: Alternate BFR (Big Falcon Rocket)

"Panspermia" often refers to life coming from elsewhere, from a comet or meteorite from another planet. What I described is life on Earth coming from earlier life on Earth. So I guess you could call this a special case of Panspermia.

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#91 2018-01-15 13:34:16

Void
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Registered: 2011-12-29
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Re: Alternate BFR (Big Falcon Rocket)

Well this is fun.

Is there a booger monster on Mars?

Panspermia, Transpermia? Yes, Bad VOID

http://www.worldscientific.com/doi/abs/ … 75260_0019

So, apparently now we have the options of Ballistic Panspermia, where a significant object can transfer micro-organisms is added to by the possibility that the solar wind can pluck a bug out of the atmosphere, and I suppose on the most rare of occasions one of these might survive to start a life process on another object.

Last edited by Void (2018-01-15 13:42:28)


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#92 2018-01-15 14:10:18

RobertDyck
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Re: Alternate BFR (Big Falcon Rocket)

Life could have started on Mars, then travel to Earth on a meteorite. Or could have started on Earth, then travel to Mars. Or started on Earth before the impact of Theia, the planet that impacted Earth to form the Moon. Or life could have started on Earth, travelled to Mars via asteroid impact throwing rocks into space, lived on Mars for some time, then an asteroid impact on Mars threw rocks into space causing it to travel back to Earth. That life on Earth could be a hybrid of life that stayed on Earth with life that travelled to Mars and back. In all of these scenarios, life hasn't evolved on Mars since it froze about 4.5 billion years ago. Since Earth has that much more evolution, chances are any life on Mars will be as primitive as archaea. It may have some exotic features that life on Earth doesn't, but as others have said, I expect our immune system could handle it easily. It may not be able to handle conditions in a human body. It may love warm, wet, salty, and high iron such as hemoglobin in our blood, but any life on Earth at that time was poisoned by oxygen. And it turns out there's a certain type of leukocyte (white blood cells) in our body that uses a spray of nitric oxide (NO) as "bug spray" to kill invading organisms. Chances of a 4.5 billion year old single cell organism that hasn't had the advantage of that many years evolution, chances that it could successfully invade our body? Rather slim.

Last edited by RobertDyck (2018-01-15 14:15:50)

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#93 2018-01-15 15:58:28

Oldfart1939
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Re: Alternate BFR (Big Falcon Rocket)

OK, now getting back to the subject of this particular thread:
There have been some great suggestions made, but all are dealing with the deep space architecture of the BFR. So...what if Musk succeeds in building a BFR first stage and encounters subsequent problems? We then have a very heavy lift to LEO, and then let the permutations and combinations begin again.
As I see things, the first goal for SpaceX is getting a BFR "grasshopper" built and flown at McGregor, Texas. That's essentially all I can see happening in the next 2 years.

P.S. for Robert; very good synopsis of the early Earth life seeding scenarios.

Last edited by Oldfart1939 (2018-01-15 15:59:33)

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#94 2018-01-20 11:46:25

Void
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Posts: 3,011

Re: Alternate BFR (Big Falcon Rocket)

O.F. pointed out to me his important contribution on this thread, #79, which I guess I should have studied more.  Spacenut, as I recalled also mentioned ion rocket repositioning of external fuel tanks.
Quote:

Void-
The external fuel tank option was actually hidden in my proposal of shipping fully fueled "modules" to Mars orbit. Using an ion propulsion unit would be ideal for these. I then propose mating these "fuel modules" with propulsion units attached to the Earth return vehicles. So yeah, I'm proposing a lander/ascender stage which would be left in Mars orbit upon return to Earth. Yes, there is a lot of orbital assembly involved, but nobody said this would be a piece of cake to accomplish. Maybe--just maybe--we should consider building a von Braun "bicycle wheel" space station in Mars orbit so there would be a chance of getting some gravitational reconditioning prior to a Mars landing? And before a return Hohmann transfer ballistic orbit back to Earth?

Electric Rocket transfer of external fuel tanks is big I think.  I was focused only on attaching external fuel tanks to Alternate - BFR.  Not that that is a bad idea either for some circumstances

My recent conversation with O.F. in the "Human Missions/Deep Space Gateway; a bad joke by NASA?" section stimulated a sub-part idea for the use of ion rocket positioning of external fuel tanks.

To begin with the notion I had was that if a fuel plant were operational on the surface of Mars, then a BFR tanker could launch to Martian orbit, refuel a movable fuel depot in orbit.
When the Depot was filled ion propulsion could move it up to a very high orbit of Mars.  Then a BFR crewed could launch from the surface of Mars, and only be fueled for that launch to reach the depot, and be fully refueled for a mission to another place, not necessarily the Earth.

If it were launching to Earth from a high Mars orbit, and it were fully refueled (Internal Tanks, and perhaps External tanks as well), then it might be able to avoid a Hohman transfer method, and instead be able to use a Ballistic Capture launch window, and bring the ship back to the Earth/Moon system early.  This could be attractive, if you want to re-use the BFR more often possibly.  There may not need to be a crew on board, if all of the passengers, had decided to stay on Mars or to take a different flight.

Maybe I have that right?

Anyway it occurred to me that similar tricks could be done for fuel from Earth and the Moon, moving it by ion rocket to high launch orbits, primarily for launching to Mars, Venus or the Asteroids I would suppose.

This of course if a sub-part of the total ion rocket propelled "Barge" proposal.

Is my head muddy, or is this somewhat sensible?

Last edited by Void (2018-01-20 12:01:26)


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#95 2018-01-20 12:11:36

GW Johnson
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From: McGregor, Texas USA
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Re: Alternate BFR (Big Falcon Rocket)

Well,  we need some much-larger ion thrusters.  NASA does seem to be working on such things,  or claims to be.  We'll see. 

I personally like the idea of unmanned orbit-to-orbit transfer of supplies and equipment by electric propulsion.  It's a slower trip,  so you pre-position the stuff well ahead.  Could be stuff like landers and their propellants,  and return vehicles (if different from the transit vehicle to Mars) and their propellants. 

The other things we need are (1) in-space transfer of propellants,  and (2) how to tie a supply dump of objects together on-orbit so they don't drift apart,  without a lot of docking assembly.  Tethers?  Nets?

Propellant transfer with storables is already being done at ISS,  although we need to learn by experience how to do this from the Russians,  who have been doing this for some years now.  With cryogens,  that's a whole 'nother experience and technology base to develop.  However,  it is crucial to Musk's BFR/BFS concept.  He may get there before NASA.  We can always hope.

GW

Last edited by GW Johnson (2018-01-20 12:13:05)


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#96 2018-01-20 15:30:11

Void
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Re: Alternate BFR (Big Falcon Rocket)

Your thinking seems like wise counsul.
I am not totally sure what the future is going to be like.  Peter Zeihan says that the baby boomers are turning into "Get off my lawn consirvatives"  But we will be dying out over time.
He also says that the Millenials are disenchanted with the promises they were given of a happy life being not fufilled.  So already 45% of them voted for Donald Trump.  He says that they are already thinking like 60 year olds.  He indicates that that trend will persist through the remainder of our lifetimes.  He thinks that America is the least populist that it will be until at least 2070?  So, how do we find a way to blend with useful purpose, the comming populist nation of America with a world where the demographics stink with the exception of some of our friends.  Of course if we are space avocates we want to do the best job we can.  I don't actually have this figured out yet, but it may have to do with delivering real rewards that people(s) can recognize as helping their personal lives.
As for electric rockets, perhaps if SpaceX gets what they are after, that is a settlement on Mars, they will hope to make the process more elegant.  Perhaps they will think to support electric rockets, external fuel tanks, and utilization of Phobos and Demos and the Moon.  We might hope.  Since now Elon Musk talks about special methods for BFR to visit the Moon, maybe it is already happening.
And their are also Jeff Bezos, and the others, perhaps Amazon wants to deliver fuel tanking to Mars proximate locations and make money for it once they have done what they might do with the Moon.
Hope has a place in our dreams.
Wouldn't it be amusing if Amazon.com/Jeff Bezos sold SpaceX/Elon Musk refueling?


If there are buco Bucks involved as a profit, wouldn't Amazon.com want them?
In that case might they not invest in significant methods to do it?
Very amusing, I hope.

Last edited by Void (2018-01-20 15:30:57)


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#97 2018-01-20 23:02:19

Oldfart1939
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Registered: 2016-11-26
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Re: Alternate BFR (Big Falcon Rocket)

Void-
I've been a supporter of Elon Musk, but he sometimes allows his enthusiasm to overcome his usually good engineering judgment. I've also been a big supporter of Robert Zubrin and his Mars Direct architecture. So my comments here are maybe going to be a heresy to both concepts. But the biggest thing which has occurred since the Zubrin-Baker proposal is orbital assembly becoming somewhat routine--especially at the ISS. So my concept of "how to get our asses to Mars" is something of an eclectic approach. Of necessity, there needs to be some sort of refueling the BFR in orbit; that seems to be a new bridge we need to cross before the BFR journeys out of LEO into a Hohmann transfer trajectory. That's really why I've been proposing modular architecture, and launching fully fueled modules into LEO, then attaching some sort of engines or alternate propulsion systems--depending what they need to accomplish. If we need to leave LEO with a crewed mission, the "fuel Module is reassembled with the crew vehicle and a propulsion module at opposite ends. Otherwise, we hook on a Electric propulsion module and send it on a "slow boat trajectory" to the appropriate planetary destination. In my own strange way, I'm combining the best of BFR and Mars Direct concepts to get us to the Red Planet, and BACK! Having a fully-fueled module waiting in Mars orbit is what we need to get back to Earth from LMO, after we utilize ISRU to get from Mars surface back to Mars LMO.
My reasoning is there is simply too much being asked of the pioneering missions for them to provide a thousand metric tonnes of propellants from the get-go. This is the redundant and safer way to proceed. I'm not nearly so risk adverse as NASA, because there is always death looking over the shoulder of anyone riding a rocket. But this is (hopefully!) not a "stupid is that stupid does" approach.

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#98 2018-01-21 11:16:52

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 16,557

Re: Alternate BFR (Big Falcon Rocket)

The closest building of modules is the oldspace redu of the ISS modules that nasa had in storage by Lockheed to which I would rather have ATK leading that with the track record with the cygnus upgrade to be able to launch on anything to which they have already been able to do.
So whom has the money to invest for the later reward of being able to say we can do it, this is the Musk approach and seems everyone is buying it as in the Falcon 9.

Looking for ION Drive topic or will create one....

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#99 2018-01-21 16:22:54

Oldfart1939
Member
Registered: 2016-11-26
Posts: 1,764

Re: Alternate BFR (Big Falcon Rocket)

SpaceNut: what I have in mind is a new module similar in size and propulsion capability to the Falcon 9 second stage, except carrying NTO and Aerozine 50. Also, propelled beyond Earth orbit by an interstage using Ion Propulsion. These would be "propulsion modules."

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#100 2018-01-21 16:28:48

Void
Member
Registered: 2011-12-29
Posts: 3,011

Re: Alternate BFR (Big Falcon Rocket)

Please have a look at this.  You caused me to go in this direction....
......

Our conversation has lead me to suggest now that there should be four flavors of upper stage BFR.
Three are already contemplated:
1) Passenger.
2) Cargo
3) Fuel Tanker-Planetary
I now suggest:
4) Fuel Tanker-Interplanetary smile
This upper stage would have the following alternate qualities.
-It would be able to land almost empty on the Earth and or Mars.
-It's amount of engine power would be reduced from that of a Fuel Tanker-Planetary, because it would not be launched up to orbit with a fuel load more than it needed to achieve orbit.  Even so, it should be able to land if it is refueled in orbit.  Being able to land is important because serious maintenance can be best done on the surface of Earth.  Relatively shirt sleave environment with the best service infrastructure in the solar system.
-It should be constructed so that it can be daisy chained with other BFR upper stages of various sorts.
-All BFR upper stages should be built to be flexible, as to if they will use a Hohmann transfer, or a Ballistic Capture.  They should also be flexible as to if they would do a Mars direct Aeroburn, or instead to a capture to orbit and a less stressful Aeroburn from a Mars orbit, or an Earth orbit.
-I also suggest the gradual integration of Ion Propulsion as it "Grows Up"  and which has been mentioned by others into this interplanetary "Barge" method.
So, with these proposed modifications I suggest a massive increase in flexibility, and that there could be benefits down the road that are not currently anticipated.
......
While initially the problem it could solve is the risk that the refueling plant on the surface of Mars would be insufficient, or could break down. (Murphy's Law).........
Then down the road, when you do get your refueling plants going on the surface of Mars and perhaps even Phobos, Demos, and Asteroids, do you then have the option to reverse the flow, and sell propulsion mass back to the Earth/Moon system and also to the Asteroids and Venus?
That would be just cool.

I hope it actually makes sense.

Oh, guess I am not done...

Apollo 13.  Having the LEM with them is what saved their lives.  Similarly, having additional resources with, might offer salvation from a disaster, if you plan right.

Of course daisy chaining BFR upper stages also adds complexity, and the possibility that if an interplanetary tanker blows up it might take out the others.  So you would need to do some serious fail safe thinking about this.

We have already covered the notion (G.W.) that extra mass along could offer better radiation protection, so that is a benefit possibly available.

I am also working on a notion of how to do maintenance on Mars in an underwater environment.  But that is nasty so far.  Engines don't like water I expect, especially salt water.  I'm not there yet but so far it is either a diving bell, or a engine cover, such as the space shuttle had for being transferred.  How you get this whole thing though the ice and into the bottom of a reservoir is another problem.  Not there yet.  Maybe it will make more sense to just have a big metal enclosure.  Don't know.

Last edited by Void (2018-01-21 16:50:16)


I like people who criticize angels dancing on a pinhead.  I also like it when angels dance on my pinhead.

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