Author Topic: MCT Speculation and Discussion Thread 4  (Read 626298 times)

Offline envy887

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Re: MCT Speculation and Discussion Thread 4
« Reply #1960 on: 04/22/2016 06:05 PM »

The other question is how they will want to size the Raptor. At the currently stated 2300kN a single Raptor would be rather underpowered for throwing 100t into LEO, although probably not worse than the Centaur US. A single 2300 kN engine would be ideal for TMI and Mars return though, and dragging extra engines to Mars and back isn't ideal.

You're going to need multiple engines to propulsively land BFS back at KSC, Brownsville or wherever, which is absolutely critical for the economics of the architecture. I'm assuming extendable/discardable nozzle extensions on the BFS raptor, which may be a distinctive variant from the initial upper stage raptor vac.

Besides, if I was the commander of a 100 individual interplanetary spaceship, I'd either want engines with a ludicrous reliability or a few with a wide gimbal so I have engine out redundancy. Nobody wants to be marooned.

They are going to be carting a few unnecessary engines with them, I bet the most edible of my cowskin hats on it.

A single 2300 kN SL Raptor would be about as much overkill for a ~120t BFS as a single Merlin is for an empty Falcon S1, so I don't know that you need multiple engines to land. BFS will likely do a fully aerobraking reentry with minimal reentry burning, so the 3-engine Falcon burns don't have a BFS parallel. If you want to land 100t of payload on Earth, you might need more Raptors, but I can't imagine a non-abort scenario where that's likely. And I don't see Raptors as feasible launch abort propulsion, so any LAS will need SuperDracos or similar.

Redundancy is a good point, but would have to be optimized against available abort modes and payload reduction. If there's always a viable abort and the engines are highly reliable it might make sense to axe the dead weight. Or they might reoptimize to 150 kN at SL and always use 2 Raptors thrusting through the BFS COM.

Offline Oli

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Re: MCT Speculation and Discussion Thread 4
« Reply #1961 on: 04/22/2016 07:39 PM »
Another thing that virtually no one here talks about is MARS ORBITAL RENDEZVOUS.

If the BFS can be refueled in LEO then it can likewise be refueled in LMO if propellant can be brought their.

This would break the DeltaV budget for Earth return into two legs, assent to LMO and then TEI resulting in a vastly smaller vehicle AND a faster Earth return then would be possible with a single direct launch of even a huge vehicle.

To make the vehicle capably of departing for Mars it must start at EML-1 fully fueled which again will allow for a faster transit then a large vehicle starting in LEO.

To get the propellants to LMO and the vehicle to EML-1 you use the same solution a SEP tug, fist it moves the BFS to EML-1, picks up and drops off fuel between LEO and EML-1, then makes a fuel run all the way out to mars to rendezvous with the BFS a second time and finally returns to Earth to repeat the cycle.

The BFS would only need around 4-5 km/s DeltaV capability in this scenario which makes it hugely smaller and simpler, to launch to LEO the BFR is a 2 stage rocket like F-9 but with reusable 2nd stage which can carry payloads other then the BFS on top.

Questions arise...
How long does the SEP tug take to bring the BFS and/or the propellant to EML-1 and return to LEO? 
How many SEP trips to EML-1 per single BFS launch to Mars and return?
How efficient are SEP solar panels after numerous long trips thru the Van Allen belts? 
How many BFTanker flights to re-fuel the SEP tug itself for its various transits to support one Mars round trip mission?  Including bringing up the BFS propellant that the SEP carries all the way to Mars orbit.
Besides the added expense, resources and complexity of developing the SEP tug.

For fast transits you want to go nuclear. See for example the DRM 5 Addendum 2. In fact I don't think one synod return is possible without EP or refueling in LMO, because the delta-v is SSTO-level or higher. From both options, EP or LMO refueling, I would pick EP because it also saves you a ton of mass in LEO and it doesn't require a huge launch infrastructure on Mars. Note that you would not refuel the BFS in LMO, the EP would bring it back. In fact all in-space propulsion would be done with EP, however the BFS would do aerocapture at Mars.

If SpaceX plans to use a reactor on Mars they could use it for NEP too, if it has sufficiently low mass.

« Last Edit: 04/22/2016 07:42 PM by Oli »

Offline jsgirald

Re: MCT Speculation and Discussion Thread 4
« Reply #1962 on: 04/22/2016 08:48 PM »
SpaceX pushes mass fractions to the limit so a 100t empty mass is probably conservative, but lets go with that. However, Saturn V was a 3 stage to orbit system, so the comparisons to a TSTO aren't really accurate.
Well, actually I thought 100t estimate to be optimistic!
I was using the Saturn thing just to make sure the numbers did make sense. Agreed, they'll be different, but actually, the SIC did stage very low, not too different from Falcon 9 on that, and this also makes RTLS easier (for a barge landing they'd need a Nimitz class barge!) which was the point really.

Quote
BFR will likely have mass fractions much closer to Falcon 9 than Saturn V, but with a better ISP than either. Falcon 9 stages at around 2.2 to 2.5 kms, and the upper stage adds about 5.3 kms to get it to LEO. With Raptor's higher ISP, it only takes about 625t of prop to get a 200t ship+payload into LEO.

If they can stage at 3.5 kms (with enough prop in the BFR to boostback to reentry at a survivable Mach 6 or 2 kms), then the upper stage/ship only has to add about 4.5 kms to LEO, which happens to be about the same performance it needs to sent 100t through TMI and do a 1 kms (ish) EDL burn at Mars. That only takes about 500t of prop.

The other question is how they will want to size the Raptor. At the currently stated 2300kN a single Raptor would be rather underpowered for throwing 100t into LEO, although probably not worse than the Centaur US. A single 2300 kN engine would be ideal for TMI and Mars return though, and dragging extra engines to Mars and back isn't ideal.

Aren't you cutting deltaV too low for comfort? I'd actually estimated a total > 9km/s just to be safe. That makes the second stage almost 7 km/s with a huge but manageable BFR, over 200t empty mass. With that you're ok with a single Raptor (2300 kN) for landing, maybe three for RTLS (again not too different from Falcon 9).

You can get to Mars from LEO with less than 4.5 km/s, but there are not many options (I've checked NASA's Trajectory Browser) and it puts a very narrow constraint. With the extra deltaV you get better margins for braking and EDL too.

Besides, if I was the commander of a 100 individual interplanetary spaceship, I'd either want engines with a ludicrous reliability or a few with a wide gimbal so I have engine out redundancy. Nobody wants to be marooned.

They are going to be carting a few unnecessary engines with them, I bet the most edible of my cowskin hats on it.
Mostly agree with that, better safe than sorry. But being Raptors an overkill, I also wonder if they will use Raptors for landing, either on Mars and on Earth. Probably smaller and lightweight pressure fed engines for landing might work too.
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Offline envy887

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Re: MCT Speculation and Discussion Thread 4
« Reply #1963 on: 04/23/2016 12:00 AM »
More than 9 kms total dV is needed for orbit, but that includes drag and gravity losses largely borne by the first stage before staging. Falcon 9 stages at about 2.5 kms horizontal velocity, but expends well over 4 kms total dV to get there... So the 2nd stage only needs to add about 5.3 kms to orbit.

All Mars injections for the next 4 synods can be done with 3.5 to 4 kms of dV from 200 km LEO:
http://trajbrowser.arc.nasa.gov/traj_browser.php?
NEAs=on&NECs=on&chk_maxMag=on&maxMag=25&
chk_maxOCC=on&maxOCC=4&chk_target_list=on&target_list
=Mars&mission_class=oneway&mission_type
=rendezvous&LD1=2015&LD2=2025&maxDT=1&DTunit=yrs&maxDV=6.0&min
=DV&wdw_width=365&submit=Search#a_load_results

100t might be optimistic. To baseline, the Falcon S2 is 8t with a fairing and can deliver at least 17t to LEO (possibly much more depending on staging velocity). Terminal landing fuel and legs add about 10% each to the F9 S1, which would bring the S2 to 9.6t. Estimates of heatshield mass vary, but typically range from 1 to 4t, or 10.6 to 13.6 total dry mass. Assuming the pressure vessel, life support, and consumables count as payload, the empty stage could carry roughly its dry mass in payload, or a 100t stage for a 100t payload.
« Last Edit: 04/23/2016 08:30 PM by Chris Bergin »

Offline Impaler

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Re: MCT Speculation and Discussion Thread 4
« Reply #1964 on: 04/23/2016 04:56 AM »
Another thing that virtually no one here talks about is MARS ORBITAL RENDEZVOUS.

If the BFS can be refueled in LEO then it can likewise be refueled in LMO if propellant can be brought their.

This would break the DeltaV budget for Earth return into two legs, assent to LMO and then TEI resulting in a vastly smaller vehicle AND a faster Earth return then would be possible with a single direct launch of even a huge vehicle.

To make the vehicle capably of departing for Mars it must start at EML-1 fully fueled which again will allow for a faster transit then a large vehicle starting in LEO.

To get the propellants to LMO and the vehicle to EML-1 you use the same solution a SEP tug, fist it moves the BFS to EML-1, picks up and drops off fuel between LEO and EML-1, then makes a fuel run all the way out to mars to rendezvous with the BFS a second time and finally returns to Earth to repeat the cycle.

The BFS would only need around 4-5 km/s DeltaV capability in this scenario which makes it hugely smaller and simpler, to launch to LEO the BFR is a 2 stage rocket like F-9 but with reusable 2nd stage which can carry payloads other then the BFS on top.

Questions arise...
How long does the SEP tug take to bring the BFS and/or the propellant to EML-1 and return to LEO? 
How many SEP trips to EML-1 per single BFS launch to Mars and return?
How efficient are SEP solar panels after numerous long trips thru the Van Allen belts? 
How many BFTanker flights to re-fuel the SEP tug itself for its various transits to support one Mars round trip mission?  Including bringing up the BFS propellant that the SEP carries all the way to Mars orbit.
Besides the added expense, resources and complexity of developing the SEP tug.

1)  I'd aim for each tug to complete 3 round trips between LEO and EML-1 per synod which would be 260 days each round trip, likely 200 outbound and 60 inbound due to lower mass.

2)  It differs for crew vs cargo missions, for crew you need BFS full of propellant at EML-1 which would be 2 propellant loads plus BFS itself, then another 2 loads of propellant delivered to EML-1 for transit to Mars which means 5 total LEO->EML-1 trips per 1 crew mission. 

For a cargo mission the slow hohomann trajectory should allow 2 BFS to be fueled from one propellant load at EML-1 and no propellant is needed at mars because a BFS on mars surface without any return cargo should make direct earth return so 3 LEO->EML-1 trips do 2 cargo deliveries or 1.5 per cargo delivery.

3)  Amorphous silicon solar panels can be self healing under the radiation environment of space and make many passes through the belts, eventually though the panels and likely thrusters will need replacement perhaps every other synod or two, the EML-1->Mars transits won't involve the belts and will likely be less stressful, I could see a tug doing one transit for the first synod then the 3 LEO->EML-1 trips the second as this keeps it closer to Earth and more easily put into unscheduled maintenance if needed.

4)  Ideally one Tanker flight corresponds to one tugs propellant load and it is a direct vehicle to vehicle transfer to avoid the need for a depot.  A load is probably around 150 mt of Metho-Lox propellant and 20-30 mt of Xenon.  Possibly the BFR simply launches a self-contained insulated tri-propellant cylinder which is equipped with all necessary transfer and cooling equipment (a bit like a self contained depot), the tug simply pushes this around while drawing the Xenon (though the tug has an integral tank too), this would avoid the need for perfect synchronicity between the launches and the tug pick ups as well as allow propellant to be accumulated in mars orbit or on Demos without requiring the tugs to loiter there.



Finally note that the above scenario would be used as a boot strapping method with the goal of getting the propellant depot in place in mars orbit and making the first few crewed missions safer.  Then we would transition to stockpiling propellant in Mars orbit sourced from Mars using the 25 mt cargo capacity from the mars surface that we know is planned.  When sufficient cargo volume is being shipped and propellant on the surface is plentiful the SEP tugs move cargo (without it being in a BFS) to mars rather then propellant, the cargo is placed into empty BFS in mars orbit and is landed.  Then the BFS is launched back to mars orbit with 25 mt extra propellant (rather then return crew) and this is offloaded when the next cargo is on-loaded.  After 12 such cycles enough propellant is accumulated to perform 1 fast crew return which roughly matches the expected crew:cargo ratio.  From this point on crew missions only need 3 SEP tug loads to EML-1 and cargo loads are better then 1:1 because the BFS itself is being omitted.

The very first crewed mission can also avoid landing on Mars as well and instead conduct an exploration of Phobos and then return via the pre-delivered propellants.  This would fit with the NASA plans which call for a gradual build up of capabilities, meanwhile the ISPP systems can be getting set up on the surface with the assistance of tele-robotic operation from the Demos crew.

« Last Edit: 04/23/2016 05:01 AM by Impaler »

Offline philw1776

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Re: MCT Speculation and Discussion Thread 4
« Reply #1965 on: 04/23/2016 02:32 PM »
Thank you for your thoughtful response.
If I understand correctly one tanker load to LEO is 150 + 30 = 180 mt cargo.  Big BFR especially if you downsize your stage 2 as proposed for the BFS.  Or maybe your tanker version has larger propellant tanks to supply more delta V to LEO for the heavy cargo payload.

I see a SEP hauler approach as a follow on after initial synod missions as I am in the camp that the most likely disaster/delay scenario for SX is the huge R&D costs to develop the BFR (easier) and BFS (more difficult & riskier).  Adding a SEP increases R&D costs considerably.
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Offline Impaler

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Re: MCT Speculation and Discussion Thread 4
« Reply #1966 on: 04/23/2016 06:16 PM »
Yes around 180 mt for a propellant tanker load, but that is comparable to the mass of the BFS + 100 mt of Cargo.  I expect the BFR to have two stages like F-9 with the 2nd stage holding around 1000 mt of propellant.  BFS and the propellant tankers are both a payloads upon the BFR and of comparable mass, likewise when the SEP tug itself is launched perhaps two at a time as they won't be very massive. 

I see BFR as stand alone universal hyper-heavy lift vehicle able to carry a payload fairing up to 15m in diameter and ~40 m tall (7000 m^3) within which just about anything can be launched.

This is the safest development track because the BFR can be completed first and enter service to generate revenue and compete with SLS for any beyond Earth or heavy lift missions NASA attempts, this will basically kill the SLS and give SpaceX a monopoly on this size class of launch vehicle.  Then the BFS and SEP tugs can be developed for less then the proposed single huge BFS due to considerably lower mass and lower propellant fractions of the BFS, my calculations show a BFS of 75 mt dry mass with 300 mt propellant capacity will do the job where as the huge BFS will likely mass closer to 150 mt and hold 1000 mt of propellant.

Offline philw1776

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Re: MCT Speculation and Discussion Thread 4
« Reply #1967 on: 04/23/2016 08:03 PM »
Not totally bought in, but the much smaller BFS with Mars orbit SEP capture has a big advantage in that far less Mars colony energy and ISRU is needed per flight.
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Offline Impaler

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Re: MCT Speculation and Discussion Thread 4
« Reply #1968 on: 04/24/2016 12:26 AM »

For fast transits you want to go nuclear. See for example the DRM 5 Addendum 2. In fact I don't think one synod return is possible without EP or refueling in LMO, because the delta-v is SSTO-level or higher. From both options, EP or LMO refueling, I would pick EP because it also saves you a ton of mass in LEO and it doesn't require a huge launch infrastructure on Mars. Note that you would not refuel the BFS in LMO, the EP would bring it back. In fact all in-space propulsion would be done with EP, however the BFS would do aerocapture at Mars.

If SpaceX plans to use a reactor on Mars they could use it for NEP too, if it has sufficiently low mass.

Fast in this context means faster then Hohmann transfer, I'm aiming for 150 days.  From EML-1 the DeltaV is modest around 4 km/s, if this were attempted from LEO it would indeed be SSTO levels of DeltaV and a one synod round trip is even more brutal, I have dismissed this as a possibility long ago even with unlimited propellants, the vehicles are just too large and have too high a propellant fraction to be reasonable.

An all EP for ex-atmospheric propulsion would indeed be the most efficient solution and I see that being done for cargo with something like a container ship going from LEO->LMO and chemical rockets staying at Earth and Mars and shuttling between surface and orbit to load and unload cargo.  Combining EP with aerocapture is also highly desirable as it would eliminate the need to brake into orbit via EP, saving both time and propellant but it may require advancements in solar array stiffening to achieve. 

For crew transport I suspect the speed of chemical may be necessary to beat the radiation threat, should a radiation mitigation (shielding, drugs, etc etc) be found then EP would be preferred their as well.

Offline Vultur

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Re: MCT Speculation and Discussion Thread 4
« Reply #1969 on: 04/24/2016 04:30 AM »
Plugging the Saturn IC data in the rocket equation shows that deltaV was just over 3.3 Km/s, it also staged at a pretty low altitude (good for the RTLS thing). Let's assume that the MCT booster does likewise, that leaves about 7 Km/s deltaV to the second stage (aka BFS) which is ok if you plan to refuel and do a TMI burn.

Well, depends what kind of orbit it goes to. If it goes into a pretty low orbit (maybe 9.5 km/s or so) to be refueled, and the first stage does 3.3 km/s, that only leaves 6.2 for the second stage.

Or are you counting the propulsive landing delta-v into the 3.3?

Quote
As per word of Musk, the ship will be capable of putting 100 t of useful mass on Mars, so let's make it another 100 t for structure (engines, TPS, legs, you name it). So that leaves a 200 t dry mass vehicle, capable of 7 km/s deltaV, with engines giving a Isp of 380 s you need a whopping 1150 t of propellant and a total BFS mass at lift off of about 1350 t.

Sounds pretty reasonable.

If the needed delta-v can drop to 6.2 km/s, the propellant mass can go down to about 860 tons.

Offline su27k

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Re: MCT Speculation and Discussion Thread 4
« Reply #1970 on: 04/24/2016 05:04 AM »
RB:  You completely inverted the meaning of 'Battlestar Galactica'.  That was Zubrin's pejorative term for a single huge vehicle that carries all propellant from Earth which was the NASA plan in the 90 day report.

Zubrin's argument was two fold, use insitu propellant on mars to reduce outbound propellant needs (which we all agree Musk is doing) AND using a number of smaller modular elements that serve specific roles and provide redundancy.  The Battlestart Galactica term was specifically about not making a single all inclusive budget busting vehicle designed to perform multiple tasks.

I think the BSG comment was referring to a big NTR vehicle that is assembled in orbit, especially if the assembly also requires the space station, which I assume would be a major cost driver. Neither the "big" BFS as 2nd stage, nor the "small" BFS as payload with a separate 2nd stage qualifies as BSG.

The BFR/BFS is only big because SpaceX's cargo requirement is hugely ambitious (100t to Mars surface), it wouldn't be so big if the cargo requirement was reduced to be inline with what Zubrin or NASA imagined. I don't think he overall dry mass of the entire system would change much between "big" BFS and "small" BFS, the only difference would be the mass you send through TMI.

Offline Oli

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Re: MCT Speculation and Discussion Thread 4
« Reply #1971 on: 04/24/2016 02:18 PM »
The BFR/BFS is only big because SpaceX's cargo requirement is hugely ambitious (100t to Mars surface), it wouldn't be so big if the cargo requirement was reduced to be inline with what Zubrin or NASA imagined.

I'd say NASA is currently downsizing its Mars plans, not in terms of payload landed on Mars (still ~80t), but in terms of the size of the individual elements. It's now considering 27t or even 18t landers (instead of 40t), chemical in-space stages with masses around 40t, SEPs with a few hundred kw. Nothing monstrous. In fact the only thing monstrous left is SLS.

All that I suppose in an effort to save cost. SpaceX does exactly the opposite, it's going very big (of course SpaceX attempts to colonize Mars instead of sending 4 people every few years).

That's why I fear that SpaceX will present a paper at IAC but since it's so diametrically opposed to NASA's evolvable Mars campaign it won't have any impact. In fact it might even give congress more legitimation to push forward with SLS (Look! SpaceX wants to build an ever bigger rocket!).
« Last Edit: 04/24/2016 02:46 PM by Oli »

Offline the_other_Doug

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Re: MCT Speculation and Discussion Thread 4
« Reply #1972 on: 04/24/2016 05:40 PM »
The BFR/BFS is only big because SpaceX's cargo requirement is hugely ambitious (100t to Mars surface), it wouldn't be so big if the cargo requirement was reduced to be inline with what Zubrin or NASA imagined.

I'd say NASA is currently downsizing its Mars plans, not in terms of payload landed on Mars (still ~80t), but in terms of the size of the individual elements. It's now considering 27t or even 18t landers (instead of 40t), chemical in-space stages with masses around 40t, SEPs with a few hundred kw. Nothing monstrous. In fact the only thing monstrous left is SLS.

All that I suppose in an effort to save cost. SpaceX does exactly the opposite, it's going very big (of course SpaceX attempts to colonize Mars instead of sending 4 people every few years).

That's why I fear that SpaceX will present a paper at IAC but since it's so diametrically opposed to NASA's evolvable Mars campaign it won't have any impact. In fact it might even give congress more legitimation to push forward with SLS (Look! SpaceX wants to build an ever bigger rocket!).

Yeah, I don't think the SpaceX Mars architecture is going to be anything that even remotely resembles the NASA Mars DRA.  Which, I will argue, is designed to land four people on Mars not once every few years, but once every decade or two, at best.  The only big plus to NASA's Mars DRA is the potential build-up of infrastructure in cis-lunar space, which is useful for both Mars and Moon exploration support, regardless of which program it is built up under.  (Note that all Musk has ever said about the Moon is, paraphrasing, "it's on the way, I guess we should look at how to get there, but it's not anything like a goal of the architecture to be able to go to the Moon".)

I, for one, would like to see a new interplanetary transportation architecture be designed to support more than one possible destination, I guess... ;)
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Offline CuddlyRocket

Re: MCT Speculation and Discussion Thread 4
« Reply #1973 on: 04/24/2016 08:39 PM »
(Note that all Musk has ever said about the Moon is, paraphrasing, "it's on the way, I guess we should look at how to get there, but it's not anything like a goal of the architecture to be able to go to the Moon".)

I, for one, would like to see a new interplanetary transportation architecture be designed to support more than one possible destination, I guess... ;)

Just because going to the Moon is not a goal of the MCT architecture doesn't mean the system won't be capable of being used to go to the Moon. I'm sure people will come up with all sorts of non-Mars uses for the MCT architecture once it's in existence (or even before).

Offline mfck

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Re: MCT Speculation and Discussion Thread 4
« Reply #1974 on: 04/27/2016 01:03 AM »
(Note that all Musk has ever said about the Moon is, paraphrasing, "it's on the way, I guess we should look at how to get there, but it's not anything like a goal of the architecture to be able to go to the Moon".)

I, for one, would like to see a new interplanetary transportation architecture be designed to support more than one possible destination, I guess... ;)

Just because going to the Moon is not a goal of the MCT architecture doesn't mean the system won't be capable of being used to go to the Moon. I'm sure people will come up with all sorts of non-Mars uses for the MCT architecture once it's in existence (or even before).
Imagine Hubble in the Smithonian.

Offline Robotbeat

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Re: MCT Speculation and Discussion Thread 4
« Reply #1975 on: 04/27/2016 01:34 AM »
(Note that all Musk has ever said about the Moon is, paraphrasing, "it's on the way, I guess we should look at how to get there, but it's not anything like a goal of the architecture to be able to go to the Moon".)

I, for one, would like to see a new interplanetary transportation architecture be designed to support more than one possible destination, I guess... ;)

Just because going to the Moon is not a goal of the MCT architecture doesn't mean the system won't be capable of being used to go to the Moon. I'm sure people will come up with all sorts of non-Mars uses for the MCT architecture once it's in existence (or even before).
Imagine Hubble in the Smithonian.
Imagine Hubble keeps operating nearly indefinitely. Much better, IMHO... ;)
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Offline The Amazing Catstronaut

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Re: MCT Speculation and Discussion Thread 4
« Reply #1976 on: 04/27/2016 08:38 AM »
Imagine Hubble keeps operating nearly indefinitely. Much better, IMHO... ;)

Nah, we all love it but it's old. Build a one significantly newer and 4x the size. Hell, with that kind of capacity you could have a dedicated manned observatory station, or even throw a hubble-esque telescope into a solar orbit.
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Offline su27k

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Re: MCT Speculation and Discussion Thread 4
« Reply #1977 on: 04/27/2016 10:02 AM »
That's why I fear that SpaceX will present a paper at IAC but since it's so diametrically opposed to NASA's evolvable Mars campaign it won't have any impact. In fact it might even give congress more legitimation to push forward with SLS (Look! SpaceX wants to build an ever bigger rocket!).

Well Bolden already used this line of argument a few weeks ago, so the cat is definitely out of the bag...

I do wonder if the paper will include some cost estimates, on one hand cost will be a major justification for the architecture, on the other hand realistic cost estimate may give their commercial competitors some unique insights into their operations.

Offline Bynaus

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Re: MCT Speculation and Discussion Thread 4
« Reply #1978 on: 04/27/2016 10:22 AM »
Imagine Hubble keeps operating nearly indefinitely. Much better, IMHO... ;)

Nah, we all love it but it's old. Build a one significantly newer and 4x the size. Hell, with that kind of capacity you could have a dedicated manned observatory station, or even throw a hubble-esque telescope into a solar orbit.

You wouldn't want a manned observatory station - too much vibration and other interference. Better to have an unmanned observatory which can reached and upgraded quickly and cheaply, as needed. Which is exactly what a "cislunar" BFS could provide.
More of my thoughts: www.final-frontier.ch (in German)

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Re: MCT Speculation and Discussion Thread 4
« Reply #1979 on: 04/27/2016 01:15 PM »
Imagine Hubble keeps operating nearly indefinitely. Much better, IMHO... ;)

Nah, we all love it but it's old. Build a one significantly newer and 4x the size. Hell, with that kind of capacity you could have a dedicated manned observatory station, or even throw a hubble-esque telescope into a solar orbit.

You wouldn't want a manned observatory station - too much vibration and other interference. Better to have an unmanned observatory which can reached and upgraded quickly and cheaply, as needed. Which is exactly what a "cislunar" BFS could provide.
The manned portion could float nearby.  As far as that issue ruling out that particular use of non-Mars MCT.
The pork must flow.

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