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#26 2018-01-08 19:35:10

Oldfart1939
Member
Registered: 2016-11-26
Posts: 1,646

Re: Alternate BFR (Big Falcon Rocket)

Well, it seems as though only the now 28 year old Mars Direct mission proposal is the ONLY one to consider the debilitating effects of prolonged weightlessness. Neither the Boeing nor Lockheed-Martin plans make provision for the issue and neither does NASA.
Musk needs to hire Bob Zubrin to do some critical thinking and analysis of the BFR plan.
Meanwhile, my proposal is very simple. Everything is constructed in easy to orbit modules. They are crew habitation/living modules, cargo modules, and a variety of power modules. The power modules are of two varieties. Fuel plus propulsion units, and fuel only. This allows an in-orbit mix and match, tinkertoy approach for building the necessary mission architecture. I propose that the space based only modules be NTO/UDMH powered, and the landers be equipped with adequate fuel excess of UDMH and LOX, which can be reloaded with LOX on the Mars surface. I haven't done the math yet, but my proposed crew/some cargo lander module be a combined habitation module plus a special space/surface/space unit. The cargo units would NOT be equipped for return to orbit around Mars, so more cargo can be brought to establish the base facilities. These deep space only modules would not be regarded as throwaway units, but would remain in orbit around either Earth or Mars until the technology of ferrying sufficient fuel to them is developed.
I originally formulated this approach for the Falcon Heavy, or possibly a Falcon Super Heavy. I did some preliminary math for an enlarged Red Dragon style spacecraft with a mass landed of 26,000 kg, and it is JUST possible.

Last edited by Oldfart1939 (2018-01-09 13:56:29)

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#27 2018-01-08 20:49:20

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

Re: Alternate BFR (Big Falcon Rocket)

Spacenut stated and inquired:

Nasa indicates that to land 88,200 lbs of payload, the throw to mars is in mass range of 176,400 -242,500 lbs would be required in Mars orbit prior to EDL. So even Nasa is looking at half that of the BFR for a mars mission to the surface.
Void the mission stay time of 30 days on the surface would require a duration from launch to splash down of 500 days. With the long stay on the surface is a duration of 900 days. The outbound and return trip times unless we used a lot more fuel on either end is in the 6 to 9 month travel times each way without dropping payload mass to mars.
My question is what are we delivering to mars that needs to have such a high mass level.....

I am not in the least bit angry, so lets be sure that I have every intention of being decent.  Perhaps indeed I have something big to try to learn.  A mistake I have not understood.

Still it appears that you have not taken note of my intentions at this point. 

If I were to try to reason this out, I have decided that for a scouting mission there would be no reason to land humans on the planet.  In fact there would be good reasons not to.  Not having a lander would simplify the mission.  What I would hope for is that international space programs would land probes on the surface.  Probes that would be carried by BFR to Mars orbit.  Included in my wish list is at least one successful sample return to orbit that BFR could intercept, package for shipment back to an Earth/Moon location.

The other things I want is an aerocapture of BFR upon it's arrival, BFR ending in orbit of Mars.

Also, I want BFR to take a core sample from Phobos or Demos, I also want it to scan the moon(s) with radar up close.  I want it in a landed state on those moons.  I want sonar to also sound the asteroid through the legs.  For this mission BFR would require special legs, that spread very wide.  They would most likely be left behind after their usage was complete.

For this scouting mission no mining equipment would be included, and none of the solar panels to make insitu Methane and Oxygen.  So, that is a very large weight saving.

Ideally there would be no humans included, it would all be robotic, but I don't think our level of robotics is sufficient for that yet.

But only as many humans as is necessary should be included.  With that it should be more possible to include safety equipment to try to keep them healthy.

Quote:

The outbound and return trip times unless we used a lot more fuel on either end is in the 6 to 9 month travel times each way without dropping payload mass to mars.

Yes, I mentioned external fuel tanks, to give the craft more range.  Elon Musk does not think that fuel is the big problem.  He intends to reuse his hardware to save costs.

Well I am thinking similar.  Here is a picture of the space shuttle external tank.

https://en.wikipedia.org/wiki/Space_Shu … ernal_tank
300px-External_Tank.jpg

So an external tank for BFR which contains Methane and Oxygen instead of Hydrogen and Oxygen should be easier.  Further, once it is in orbit it will be much easier to manage than trying to fly the whole assemble as one to orbit.

How does it get to orbit?  Well I would perhaps be launched by a Falcon Heavy.

How many external tanks could you attach to BFR?  Well quite a few I should think.

It is my expectation that these will be disposable, as they will only be needed for initial scouting missions, or perhaps to go further than Mars.

So, except for adding cost, this should extend the capabilities of BFR, so that for scouting missions it will not need insitu refueling.

So, yes now we have an enormous improvement in our access to fuel, to do strange orbital pathways.

I also mentioned using a Hohmann transfer to get to Mars, but to use a ballistic capture method to return to Earth.  With the extra fuel, and the forgiveness that ballistic capture offers, I hope to get to Mars, do a survey, get out and go back. 

Well here I could be stepping in it.  I simply don't know enough about the details of the ballistic capture method, but it sounds promising.
1) In some cases it may use less fuel.
2) Unlike the Hohmann transfer it can be implemented at many different times.
3) A drawback exists in it in that it may take some more time for the trip.  But as far as I am concerned, it would be much better that hanging around on Mars waiting for the next window.  I also suspect that it is a more lenient method.  If you have a critical system failure during the burn, I think that particularly with having the luxury of more fuel, you could recover.  With the Hohmann transfer, you might be totally screwed if you had a critical system failure at the time of the needed burn.  But maybe I don't understand orbital methods well enough.  If I have a lesson to learn I want to learn it.  There is no shame in that.

Last edited by Void (2018-01-08 21:26:09)


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#28 2018-01-08 21:33:38

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

Re: Alternate BFR (Big Falcon Rocket)

The objective would be to both search for evidence of life, and to assess the resources at various locations.  Particularly water ice.

I previously mentioned a probe that would be ejected from BFR which would be capable of steering to a particular location but would not land it would crash.  Making a big KABOOM!, and so a big hole to inspect.  (Probably from orbit).   BFR could likely have some big hefty instrumentation along with it to do that.  While the probe(s) were falling, I would hope they would also do radar sounding.

I am not goofing around.  I feel that it will be important to assess, several locations, and get "Ground Proof" as one of our members insists is important.

Meanwhile if we follow the codes for planetary protection, the SpaceX might make a lot of money delivering international payloads to Mars, and selling the core samples from Phobos and Demos.

The scouting trip(s) might be financed internationally, if planetary protection methods are observed.

Oh by the way I also mentioned getting a Martian air sample while doing aerocapture.

Frankly I hope that any signal for existing life will be negative.

I also make the point that the sooner humans occupy Mars, the sooner geology may reveal the existence of extinct life.

Good Night. smile

Last edited by Void (2018-01-08 21:38:25)


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#29 2018-01-08 22:12:23

SpaceNut
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From: New Hampshire
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Posts: 15,806

Re: Alternate BFR (Big Falcon Rocket)

1 BFR is capable of bringing within it, landers of all types, Impactors or rovers at 15 tonnes a piece on orbit for selective destination choices to be made for each. Filling the BFR with 10 of any mix and match to any destination (in just 1 refueling of the bfr in earth orbit to which is musk plan for refueling), just to pepper mars with probes. With these probes being of simular design to the ones past and currently on mars all we have done is give us more chances to find what we wanted for questions answered.

If all you need is an impactor Nasa has done that with the moon to which the results are still in question as to water content at the poles, so why would that change for mars as its an indirect observation as well.....

We need probes that are way more capable....these are not cheap and musk does not make them

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#30 2018-01-08 23:29:54

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

Re: Alternate BFR (Big Falcon Rocket)

Why do you avoid the important issues?

Obviously the notion of space travel as you previously fossilized yourself to is over.

Silly fretful calculations of math are obsolete.  Granted you have to get that stuff right, but the rules of the game have changed.

Fuel abundance is not a show stopper anymore, so the game can be played in many new and different ways.  Adapt!

And, as I already said, I expect many of the probes to be of international origin, and for SpaceX to be paid to deliver them.

What is it that you want just put 4 BFR's in a random spot and hope it works out?

And goodnight. This time for sure.  smile  I am very comfortable with where I am with this.  I think you are very wrong.

Last edited by Void (2018-01-08 23:33:23)


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#31 2018-01-08 23:40:30

Oldfart1939
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Registered: 2016-11-26
Posts: 1,646

Re: Alternate BFR (Big Falcon Rocket)

I do not see the BFR as being ready to fly by 2022. That's why I have suggested my "modular architecture" relying on the Falcon Heavy architecture.

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#32 2018-01-09 01:57:09

kbd512
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Posts: 2,883

Re: Alternate BFR (Big Falcon Rocket)

Quite frankly, I don't think Mr. Musk is in a position to even test BFR by 2022.  He has built one functional rocket with a reusable booster and a triple core variant of the same rocket that, according to him, required so many modifications it's barely the same rocket.  It'll be another two years or so before any significant flight experience with the Falcon Heavy exists.  NASA built something the size of BFR with unlimited funding, but it was too expensive for significant use and too limited in what the agency could actually use it for.

Stick with small multi-use rockets that are inexpensive to construct and refurbish.  Assemble bits and pieces in orbit at ISS.  Stick with electric propulsion for cargo and storable chemicals for humans.  Apply the supersonic retro-propulsion concept to landing heavier payloads on Mars.  Use purpose-built orbit-to-orbit transport vehicles, purpose-built orbital stations, and purpose-built landers.  After we're really sure that water exists and can be extracted in the required quantities, then we can concern ourselves with colonization.  If we just did that, then we could have the basic infrastructure ready in about a decade, the first orbital mission upon the next opportunity, and the first manned landings upon the following opportunity.

Anything more sophisticated than that for exploration missions is not going to happen in our lifetimes.  It'll cost too much to develop and test and take too long.  Nobody knows what will or won't work without testing, so NASA won't authorize the mission.  Keep it simple.  It's already incredibly complicated.

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#33 2018-01-09 05:43:46

louis
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From: UK
Registered: 2008-03-24
Posts: 4,704

Re: Alternate BFR (Big Falcon Rocket)

According to Musk, Space X should be ready to start building (note - building, not designing) the BFR from the second quarter of this year, so by end June.  It seems reasonable to suppose they already have a very detailed design ready to be worked on. Space X must by now have as good an idea as anyone else how to assemble a rocket, what materials to use, how to wire communications etc etc.

I think Space X are right to focus on the BFR because it will be a multi-purpose reusable vehicle.  As such its development costs will be applied over a number of discrete uses (satellite launches, ISS supply, orbital tourism, lunar tourism, E2E flights and the Mars Mission) and multiple flights.

I can't see what stands in the way of the BFR development if they have the design and they have the money and I believe they have both.


kbd512 wrote:

Quite frankly, I don't think Mr. Musk is in a position to even test BFR by 2022.  He has built one functional rocket with a reusable booster and a triple core variant of the same rocket that, according to him, required so many modifications it's barely the same rocket.  It'll be another two years or so before any significant flight experience with the Falcon Heavy exists.  NASA built something the size of BFR with unlimited funding, but it was too expensive for significant use and too limited in what the agency could actually use it for.

Stick with small multi-use rockets that are inexpensive to construct and refurbish.  Assemble bits and pieces in orbit at ISS.  Stick with electric propulsion for cargo and storable chemicals for humans.  Apply the supersonic retro-propulsion concept to landing heavier payloads on Mars.  Use purpose-built orbit-to-orbit transport vehicles, purpose-built orbital stations, and purpose-built landers.  After we're really sure that water exists and can be extracted in the required quantities, then we can concern ourselves with colonization.  If we just did that, then we could have the basic infrastructure ready in about a decade, the first orbital mission upon the next opportunity, and the first manned landings upon the following opportunity.

Anything more sophisticated than that for exploration missions is not going to happen in our lifetimes.  It'll cost too much to develop and test and take too long.  Nobody knows what will or won't work without testing, so NASA won't authorize the mission.  Keep it simple.  It's already incredibly complicated.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#34 2018-01-09 06:23:02

elderflower
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Registered: 2016-06-19
Posts: 1,096

Re: Alternate BFR (Big Falcon Rocket)

Also we need to remember that atmospheric braking on Mars can be very effective, so that we can deliver loads to the surface (at low altitude sites, not the top of Olympus I'm afraid) for little more expenditure of propellant than would be used to insert the ship into a Mars orbit.

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#35 2018-01-09 08:11:37

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

Re: Alternate BFR (Big Falcon Rocket)

Actually Elderflower I don't accept that assertion completely.  It might be more proper to say that it is not worth it to deliver a load to Olympus Mons.  Given enough fuel, you could.
Olympus Mons was just a trial balloon.  This is to find a place least likely to have life.

However I can see how this is going to go.  You guys are going to continue to circle back to what you already know, and not try to invent new things.  Just invent things that have already been invented.

I have gotten no feedback on external fuel tanks, no feedback on personal radiation armor, and no feedback on ballistic capture.

I confess that I believe my time is being wasted.

The topic is Alternate BFR not BFR-Elon Musk.  (Although his BFR is a fantastic idea, I do support it).

So, not angry, just deciding to put my time into more productive things.  Taking another break.


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

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#36 2018-01-09 09:14:34

Oldfart1939
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Registered: 2016-11-26
Posts: 1,646

Re: Alternate BFR (Big Falcon Rocket)

Void-

Don't drop out completely. New ideas are what makes this website work.

I am a big supporter of Elon Musk, but his thinking DOES need some doses of hard reality. The concept of the BFR is fantastic, but it's not on my event horizon for at least 10 years. This is why I've made proposals based on available and evolving hardware such as the Falcon Heavy. w/r Musk, I'm a supporter and not a sycophant. It's also why I believe there will be, of absolute evolutionary necessity be something similar to the Falcon X design between Falcon Heavy and the BFR (which I'm willing to wager, will shrink substantially). Six or 7 years ago, SpaceX published a series of design concepts, and Elon has settled on building something similar to the Falcon XX, skipping the intermediate Falcon X version. I suspect he'll come to his senses, and soon. There have been similar discussions to these on www.SpaceReviewEssays.com, and I'm not alone in this thinking.

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

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#37 2018-01-09 09:18:53

Oldfart1939
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Registered: 2016-11-26
Posts: 1,646

Re: Alternate BFR (Big Falcon Rocket)

Void-
You need to check some of the earlier threads here; GW has discussed ballistic capture several times. The external fuel tanks have a conceptual problem for SpaceX, based of the need for maximum reusability. Personal radiation protection is just too heavy for a non biomechanical suit. A radiation protected rover is a concept that is feasible. There. Your concepts HAVE been addressed.

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#38 2018-01-09 14:34:10

Oldfart1939
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Registered: 2016-11-26
Posts: 1,646

Re: Alternate BFR (Big Falcon Rocket)

To revisit some of my statements made earlier this thread, post # 26 to be specific. One of the keys is keeping the dry weight minimal, which means avoiding cryogenics which have low densities. Everyone looks at Isp as the key data point, but I argue for Id, which takes into account the density of the fuel component.

My architecture has been centered on use of UDMH, but I happen to prefer Aerozine 50, as it gives an incrementally better Id than either MMH or UDMH, coupled with a decent Oxidizer/Fuel ratio.

For the skeptics among us...here are the data with LOX as the oxidizer:

Fuel           O/F         Isp  (sec)         Id (kg-sec/l)          C (m/sec)

Hydrogen      5.0        381                  124                       3738

Hydrazine     0.74       303                  321                       2973

MMH            1.15       300                  298                       2938

UDMH          1.38       297                  286                       2916

Aerozine 50  1.06       300                  300                       2941

The final 3 fuels have the singular advantage of being compatible as coolant in regeneratively cooled rocket engines, and are sufficiently shock insensitive to withstand acceleration/deceleration stresses and vibration.

When dinitrogen tetroxide is used as the oxidizer component, Aerozine 50 again surges to the head of the pack w/r Id and O/O ratio.

If we are forced to consider the FIRST FEW missions before ISRU becomes reality, these are the best options. If we have Moxie only, the density of Aerozine and the necessary burn ratio becomes advantageous, and allows a semi-ISRU mission to help with payloads landed.

Last edited by Oldfart1939 (2018-01-09 14:36:02)

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#39 2018-01-09 16:52:32

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,806

Re: Alternate BFR (Big Falcon Rocket)

Commercial off the shelf does not exist in space travel parts to build launcher from ,probes, landers as these are either fully developed 1 off designs not real production models. The space X is approaching a comercial launcher value simular to what is more costly in Atlas V and Boeing's Delta family but that is all as even Atlas buys cots engines and uses common core tanks that are made via the ULA.

Space X sells nothing other than a ride to orbit for cargo and from its last launch it seems to be doing it to cheaply from a quality control stand point. The military nor anyone else can afford to lose the cargo that they pay to have space x launch. Just think if this was a manned flight what it would have just cost in lives for being this way.

Lets play we would send all the current succesfull probes and landers all again but to new sites to further the science knowledge of the location. We get a marginal benefit of specifics but do not answer the drill question for water, not the life question and so many more as they are not capable to do so.

1 off designs are around 5 years from cradle to flight give or take a year as these are always pushing the edge of technology and ability.
That is the math of doing business in an R&D mode and not for the general consumer.....

The next thing that Space x has done is the recovery of capsule and first stage to which I think all of the companies could do with fresh designs and achieve the same results which is a lowering of launch costs. The recovered/ reuse of the second stage is also not fully test as a cost reducer as Spaxe x has to make another change to the already ever changing rocket to test it out. Slow the changes and up the quality control even if it cost per launch a little more its worth the reputation saving.

The final note is the technology of artifical gravity is know, the start of radiation shielding is a matter of build and test but the space industry operates on fund through the RFP process and not self motivation to which that is the part which needs to change in the "fossilized space industry" as you put it.

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#40 2018-01-09 16:54:41

RobertDyck
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From: Winnipeg, Canada
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Re: Alternate BFR (Big Falcon Rocket)

Uh, you list hydrogen Isp=381 with LOX, but that's Isp for LCH4. LH2 in RS-25 (SSME) is 452.3 s.

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#41 2018-01-09 17:07:59

GW Johnson
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From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,565
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Re: Alternate BFR (Big Falcon Rocket)

Elderflower:

Did I get your asbestos question answered over in the "spaceplane" thread?

For this thread:

The top of Olympus Mons is virtually outside the sensible atmosphere of Mars,  and above the levels at which a high ballistic coefficient entry vehicle would come out of the entry hypersonics entering the atmosphere of Mars.  Things under a ton might come out of entry around 15 km,  but things over a ton are going to come out quite low down,  like 5 km or less.  The pull-up altitude for Spacex's BFR to reverse its orientation to do the landing burn is down around 3-5 km. 

The top of Olympus Mons is around 17 km,  I believe.  What that means is that entry to land on Olympus Mons essentially has no entry hypersonic aero-deceleration benefits,  so the delta-vee requirement to land is essentially the same as the delta-vee to launch from Mars:  3.6 km/s to low Mars orbit,  5 km/s to barely escape,  and 6+ km/s to enter an interplanetary transfer directly.

Compare that with the delta-vee to land after hypersonic deceleration to Mach 2.5-to-3 at some altitude between 5 and 25 km for a typical "planitia" landing:  somewhere between a fraction of a km/s if you can use chutes,  and between 1 and 2 km/s for propulsive landing if you cannot use chutes.  You come out of hypersonics at about 0.7 km/s (roughly Mach 3) at whatever altitude corresponds to your entry angle and ballistic coefficient. 

The bigger your entry mass,  the bigger your ballistic coefficient,  and the deeper down you come out of hypersonics,  given the same angle at entry.  The only way around that for capsule-sized loads (maybe 2 to 20 tons) is the extendible or inflatable heat shield,  so you come out high enough to use a chute.  Those things reduce your ballistic coefficient to nearer that of the well-under-1-ton probe lander we have chute experience with. 

That ain't gonna work at 20+ tons,  you still come out too low,  because ballistic coefficient goes up with mass,  no matter what your heat shield technology is.  For such big objects,  propulsive landing is just the better deal.  You come out too low to deploy a chute,  much less have it do any good.  Instead of chute + propellant weight,  just add propellant weight.  Lower complexity leads to higher reliability.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#42 2018-01-09 17:42:17

Oldfart1939
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Registered: 2016-11-26
Posts: 1,646

Re: Alternate BFR (Big Falcon Rocket)

The data I listed in the table is at 1 atm ambient pressure, not vacuum. The vacuum Isp & Id data is, as Robert says, considerably higher. That's where the 450 sec comes from. The sea level Isp and Id for methane are 299, and 235, respectively.

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#43 2018-01-09 18:41:27

SpaceNut
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From: New Hampshire
Registered: 2004-07-22
Posts: 15,806

Re: Alternate BFR (Big Falcon Rocket)

https://leehamnews-5389.kxcdn.com/wp-co … System.pdf

Precursor Missions Set the Stage for Humans
Viking 1 Lander   1976
Viking 2 Lander   1976
Pathfinder / Sojourner   1997
Global Surveyor   1997
Odyssey   2001
Spirit / Opportunity 2004
MRO   2006
Phoenix   2008
Curiosity / MSL 2012
MAVEN    2014

Future missions
InSight 2018
Mars    2020
NeMO   2022

Size Matters in Rockets
More Mass – Fewer launches, fully assembled payloads, less complex operations = lower risk

More Volume – Big mirrors, additional instruments, simple packaging = more science

More Speed – Get to the outer reaches of Solar System and beyond faster = less radiation exposure for crew and cargo

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#44 2018-01-09 19:54:52

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,806

Re: Alternate BFR (Big Falcon Rocket)

Engineers and scientists need to develop life support systems, find reliable sources of water and fuel, overcome the negative effects living in space has on the body, and find a faster way to travel.

The Human Body in Space

gee only 5 things.....

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#45 2018-01-09 20:21:42

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 5,748
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Re: Alternate BFR (Big Falcon Rocket)

Gravity: rotation
Radiation: mini-magnetosphere
Distance: quantum entanglement communicator
Isolation: smartphone, email, digital TV/YouTube, tech journals
Closed environment: we have closed environments in Canada. Shmeh

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#46 2018-01-10 12:43:30

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

Re: Alternate BFR (Big Falcon Rocket)

Well thankyou O.F.

Cooled off, intend to try to make things right.

First of all landing on Olympus Mons:  That was just a romantic idea.  If anything I would say land a probe.  Ideally a sample return mission.  I am hoping that collected dust, which would have originated below to a large extent might be analyzed, to look for any signature of life.  If lifeless, even so the dust would be an important item to study.  However, if some lower location could serve the same purpose, then dispense with the romance.

Next Item:  Louis and Spacenut both became very uncomfortable with the idea of messing with the real BFR per SpaceX and Elon Musk.  May I please be allowed to reset my intentions.

I will allow the notion that SpaceX will in fact do the four ship mission, first two that are unpersoned and then two that are personed.  I will let the powers that be fight it out as to if SpaceX will be allowed to do this.  I will not express concern over contaminating Mars, or bringing a hazardous organism back to Earth.  I will even suppose that SpaceX has a plan for all of these concerns, and that they will also be able to protect their assets and travelers.

Having released Louis, Spacenut, and others from having to rehearse a alternate concept which runs counter to the one they like, I want to be allowed to explore an alternate BFR which would come after the actual BFR formulated by SpaceX.

I hope we can find harmony in this manner.

I wish to explore:
-External Fuel Tanks for a BFR like ship.
-Additional Radiation protection methods.
-Skeleton Crew Missions.
-Ballistic Capture.

To see what it could get us.  I will leave Mars itself alone.

------
I previously suggested External tanks to be added to a BFR vehicle for non-Mars activities.
I suggested it could be expendable.

I would like to be allowed to revise that.  It seems that if Ballistic Capture can be accomplished, in some cases, you don't have to do an Aeroburn.  You can enter orbit peacefully.

If this is true for an Earth>Other planet, and also Other Planet>Earth, then I suggest a somewhat new thing which yes O.F. is modular smile  Good for you.  I do listen to other members.

I suggest a re-usable ring of fuel tanks, which would surround the Alternate BFR, and extend its capabilities.  The ring would never re-enter a planets atmosphere, except to be disposed of.

The tanks and connecting apparatus would be lofted to orbit empty, and by whatever means is most desirable.  Falcon9, Falcon Heavy,  Jeff Bezos, others.

For greater safety, the tanks would be separate.  Unlike the space shuttle fuel tanks you would not have a tank part full of Oxygen, and Fuel.

The Fuel would have their own tanks, and the Oxygen also.

Of course some assemble is required in Orbit.  Not a small thing.

I will call the ring the "Propulsion Resource Ring".  We can hope that it can be reused.  Upon failure of a tank or fluid line we will hope repairs can be efficiently be made in orbit.

The presumed advantages:
-It has to be obvious that if you have extra fuel, you have extra radiation protection.
-Also, if you have extra fuel, you can afford to use travel paths that up to now are prohibited by economy.

------
How projected Economy has now changed because of SpaceX and Elon Musk.
Fuel is cheep, if you don't crash the tanker or dispose of it in a ghost orbit.  If you have a reusable tanker which the real BFR is already associated with you are fuel rich in a way that we have never been before.  So, the rules change.  Vastly I think.

This is why I even considered high elevation landing sites at all.  A much more simple landing vehicle, but it needs to use brute force to get away with it.  It needs gobs of fuel.

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Now, about skeleton crews.  For a mission to Phobos or Demos to get samples,  there is no need to have large amounts of passengers.  No need for insitu process equipment to refuel the ship.  So, you can baby the small crew.  Lots of radiation protection.  Sleeping areas with radiation protection.  Maybe even segmented radiation suits, that the personal would wear if it does not get in the way of the tasks they need to do.  Exercise equipment.

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Now as for Ballistic Capture.  I can try to change that as well.  If instead of a Hohmann transfer from Earth to Mars, you used ballistic capture.  You could keep your propulsion resources ring with you into Martian orbit.  This would give additional radiation protection, and if the tanks have resources in them, it would allow you to return to Earth early, by some previously prohibited path.  (Just a supposed option).

If it possible to do a ballistic capture from Mars to Earth, then it potentially removes one hazard to weakened people returning from Mars to Earth.  No high Gee aeroburn into Earths atmosphere.  Instead, I believe it may be possible for them to gently go into Earth orbit, and to be given medical assistance and a more gentle return to Earth.  That's a nod to you Elderflower. smile

However, information on the web about Ballistic Capture is sketchy, and while they strongly support an Earth to Mars, Ballistic Capture, I am not so sure about a Mars to Earth Ballistic capture.

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Having said that there still stands the option of Hohmann transfers, but I don't see how you retain and reuse the External tanks in that situation.

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I'm done, thanks for not kicking me out yet.

Any modifications you want to suggest?  I'm not totally self absorbed.  I like new things.

Last edited by Void (2018-01-10 13:25:23)


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

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#47 2018-01-10 18:08:01

louis
Member
From: UK
Registered: 2008-03-24
Posts: 4,704

Re: Alternate BFR (Big Falcon Rocket)

Void,

I think the Space X mission architecture has three ships - two cargo and one human.  A BFR could easily carry a crew of 10 people, no problem, though I suspect it will be closer to 5.  I doubt you'd want more than 6 people for a first mission.  The more people, the more complexity and organisational demands.  There is I think a sweet spot for the crew number on Mission One and I would say it is between 4 and 6.  Of course that is one of the downsides of the Space X mission - it's dead if the human BFR fails.  My own preferred architecture was for two separate craft of three pioneers each - 2x3. Even if one craft fails, the Mission can still continue.


Void wrote:

Next Item:  Louis and Spacenut both became very uncomfortable with the idea of messing with the real BFR per SpaceX and Elon Musk.  May I please be allowed to reset my intentions.

I will allow the notion that SpaceX will in fact do the four ship mission, first two that are unpersoned and then two that are personed.  I will let the powers that be fight it out as to if SpaceX will be allowed to do this.  I will not express concern over contaminating Mars, or bringing a hazardous organism back to Earth.  I will even suppose that SpaceX has a plan for all of these concerns, and that they will also be able to protect their assets and travelers.

Having released Louis, Spacenut, and others from having to rehearse a alternate concept which runs counter to the one they like, I want to be allowed to explore an alternate BFR which would come after the actual BFR formulated by SpaceX.


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#48 2018-01-10 19:47:52

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,806

Re: Alternate BFR (Big Falcon Rocket)

The 2 nd stage is the part that is different in each rockets use. This image is the crewed version.

Rocket-breakdown-2.png

This is the tanker refueling either the cargo ship or the crew makes no difference as it takes 2 launches to go anywhere from orbit.
Screen_Shot_2016-09-27_at_3.21.00_PM.0.png

This is the mars flight mission plan of 2 cargo and 1 crew to mars from earth orbit.
BFR-missions-1200x750.png

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#49 2018-01-10 20:00:14

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 15,806

Re: Alternate BFR (Big Falcon Rocket)

The first mars human mission:
SpaceX+spaceship+at+Mars+base+by+Bryan+Versteeg.jpg

The is the planned colonization:
549efd3bcada96df1bee9e66e50ccb41.jpg

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#50 2018-01-10 20:11:02

GW Johnson
Member
From: McGregor, Texas USA
Registered: 2011-12-04
Posts: 3,565
Website

Re: Alternate BFR (Big Falcon Rocket)

It's hard to tell how many tanker ships must be launched with BFR first stages to refill a manned BFS ship in Earth orbit,  for sending it to Mars.  The pictorials just above show 4.  Elsewhere I have seen 5.  My own reverse-engineering estimate posted over at "exrocketman" says 6 tankers are required to fully refill a BFS on orbit. 

I do think it is unrealistic to depict BFS's on Mars as landed so close to each other or to other structures.  One mishap and you lose so much that is close by.  Plus,  the rocket jet blast is going to throw dirt and rocks as hazardous shrapnel. 

I'm also still quite skeptical that BFR first stages can be precisely landed right on the pad from which they will relaunch.  That sort of thing remains to be seen.  I could be wrong,  but it is a big jump ahead. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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