Author Topic: Alternative missions for BFR & MCT  (Read 32286 times)

Offline Hyperion5

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Alternative missions for BFR & MCT
« on: 09/14/2014 06:40 AM »
We've been debating awhile now just how Spacex's BFR & the MCT will get us to Mars and how best to accomplish colonization with them.  It's an exciting topic, not least because Mars may be a world we can transform eventually into a second home.  But you know what?  There's a whole solar system out there we have barely even begun to talk about with regards to these vehicles.  Spacex may be thinking of using these vehicles solely for Mars.  But I have news for Spacex: even the inventor of the internet did not foresee the watching of cat videos being a major use of his invention.  Something similar may also be true of Spacex's BFR & MCT vehicles (if they aren't one and the same).  "You mean like using them to produce lots of zero-g cat videos?"  Well maybe, though it seems the US Air Force has already beaten everyone to that:

There must be other profitable missions and tasks these vehicles could do for Spacex.  I can think of more than a few.  Spacex's BFR would be capable of lifting entire BA-2100 Olympus modules into orbit and building a mega-sized space station with them.  To resupply and crew the station in a single launch, simply launch an MCT, dock it with the station, and suddenly you can deliver 100 space tourists at a time to a true "space hotel".  Aside from possibly transforming space tourism, such vehicles might also make lunar bases and/or lunar tourism a real possibility.  Or they might enable asteroid mining on a previously unimagined scale.  For purely scientific missions, you might see the BFR enabling things like a Europa orbiter and lander mission, or a Titan orbiter and lander mission, or, my personal favorite, an orbiter and lander mission to Pluto. 

So let's sound off and debate just what we think the MCT and BFR will be used for besides going to Mars. 

« Last Edit: 09/14/2014 07:10 AM by Hyperion5 »

Offline Owlon

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Re: Alternative missions for BFR & MCT
« Reply #1 on: 09/14/2014 07:32 AM »
One broad mission type enabled by this is direct-injection/fast trajectories for planetary science missions. You could lift an entire super-ACES 150ish ton sort of third stage to LEO with a hefty 10+ ton spacecraft. The high-isp hydrolox stage boosts the spacecraft in a basic Hohmann trajectory with no gravity assist maneuvers, simplifying mission planning and launch window constraints and cutting flight time to the destination. The large mass budget for the payload would hopefully also save time and costs in development while allowing more space for instruments. Another bonus is the giant fairing you would have available.

You could probably do direct injection to anything within, say, Saturn's orbit, and minimize the gravity assist flybys on missions to Uranus and beyond. Alternatively, you could still use flybys liberally and just have an absurdly huge mass budget for your spacecraft.

I imagine the third stage being more like part of the payload than the rocket, and probably built by someone other than SpaceX--Boeing, Blue Origin, etc.

Online guckyfan

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Re: Alternative missions for BFR & MCT
« Reply #2 on: 09/14/2014 08:13 AM »
Why use an ACES? A hydogen upper stage would make integration hugely complex and expensive. An expendable BFR upper stage cannot be that expensive in comparison. But with refuellling in LEO I guess it would be possible to send a spacecraft into a high energy orbit and still return the upper stage. Maybe with a simple storable fuel booster that provides extra kick and/or orbit insertion at the destination.

I wonder how fast the stage could deploy the payload and do a retro burn. The earlier, the more gravity can still help to get the stage back.

Yes, MCT can bring advances in exploration of the outer solar system, I agree.

Plus cat videos.

Offline Owlon

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Re: Alternative missions for BFR & MCT
« Reply #3 on: 09/14/2014 08:59 AM »
Why use an ACES? A hydogen upper stage would make integration hugely complex and expensive. An expendable BFR upper stage cannot be that expensive in comparison. But with refuellling in LEO I guess it would be possible to send a spacecraft into a high energy orbit and still return the upper stage. Maybe with a simple storable fuel booster that provides extra kick and/or orbit insertion at the destination.

There I go, optimizing for performance instead of cost. Habits die hard, it seems. A Refueled BFR upper stage would probably be a better option (even if expended), especially since refueling seems to be the logical architecture for MCT anyway.

Offline Darkseraph

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Re: Alternative missions for BFR & MCT
« Reply #4 on: 09/14/2014 09:18 AM »
Almost positive it will have closer to home military applications, not because its designed to...but it will come out of it naturally as an unintended consequence. They weren't specific about it, but in George Friedman's book, The Next 100 Years, it was posited that improvements in private rocketry during the 2020's and 2030's would make it feasible to construct massive Geostationary constellations that both monitor all of the Earth in real time, give the crew on them the ability to command air and ground forces and have various weapons and space-denial capabilities of their own. Now some of that sounds a bit like a rehash of Reagan's Star Wars from someone who won't let the 80's Cold War years go....but some of it could pan out, and having massive amounts of cheap lifting power would certainly help construct the "Battlestars"  as they were called. A premise of the book was that part of what will make such rockets cheap is not so much that the technology is improved by reusability and ease of manufacture, but that the massive amount they'll be lifting for these platforms (i can only imagine they meant 1000's of tons+) will give them massive economies of scale and reduce costs for anyone else who wants to use them.


*entirely idle speculation...but i do believe the killer app of "newspace" will be millitary, not space hotels. I don't like that, because I am a peacenik but it seems realistic given the appetite for expensive killing machines the US Government has, and pass precedents. The amount spent by the US military in Space is almost the same as NASA's entire budget and DARPA is funding various programs to improve the tech,
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Online symbios

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Re: Alternative missions for BFR & MCT
« Reply #5 on: 09/14/2014 09:21 AM »
I'm not really that excited about Mars, or the Moon. What actually excites me is industry in space.

Think what will happen when you have all the material you need up there and build all you need up there. That is when we have a true space economy.

I think this is what the BFR and maybe MCT in a cargo role will enable.
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Offline gosnold

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Re: Alternative missions for BFR & MCT
« Reply #6 on: 09/14/2014 10:36 AM »
Putting 4 sats with mirrors as big as the MCT PLF allows in GEO would be an interesting application for the NRO. That is, if the DARPA project on deployable optics does not pan out.

Online Eer

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Re: Alternative missions for BFR & MCT
« Reply #7 on: 09/14/2014 11:24 AM »
My thoughts also drift twords economic exploitation (not, itself, a bad thing).

And I think exploitation will involve finding, recovering, and refining materials for use to create more stuff 'up there'.

At some point, that BA-2100 will provide a base for maintenance and repair of robotic fleets of self configuring drone prospectors finding icy asteroids and near earth candidates for refining in-space manufactured and stored fuels and potable supplies. Tenders will accompany smaller wings of drones to refuel and preprocess this data take, and allow on-site inspection of special opportunities.

But, ultimately, some flavor of long term habitat will emerge. Not quickly, but when in-sutu resources means fuel, oxygen, structural materials are all readily available.

BFR will get us their sooner, as operational cost, not performance, tilts the scale towards reusability.

Now, who wants the kool-aide, next?

Offline CuddlyRocket

Re: Alternative missions for BFR & MCT
« Reply #8 on: 09/14/2014 11:46 AM »
We've been debating awhile now just how Spacex's BFR & the MCT will get us to Mars and how best to accomplish colonization with them. ... There must be other profitable missions and tasks these vehicles could do for Spacex. ... Aside from possibly transforming space tourism, such vehicles might also make lunar bases and/or lunar tourism a real possibility. Or they might enable asteroid mining on a previously unimagined scale. For purely scientific missions, you might see the BFR enabling things like a Europa orbiter and lander mission, or a Titan orbiter and lander mission, or, my personal favorite, an orbiter and lander mission to Pluto.

Orbiting or other in-space colonies, perhaps. Apart from lunar bases or colonies - and any associated activities such as mining or science - there's Ceres and possibly Mercury, though the delta-V for the latter is much greater (I suspect people will want to see the similar problems of a lunar base or colony solved before even thinking of Mercury).

Perhaps orbital manufacturing? Although people will need to first discover something that's more profitable to manufacture in space! There's the perennial favourite of orbital solar-power; though all studies to date show you get more (even 24-hour) power for the same money with ground-based solar, so far as I know none of these have taken reusable launchers and the concomitant reduction of launch costs into account. One associated possibility is that of orbital data-centres; immune from Earth-based natural disasters such as earthquakes; greater security from sabotage and probably lower power requirements (cooling is the major expense).

Larger orbital telescopes, or constellations of telescopes acting as interferometers.

Propellant depots.

Offline Ben the Space Brit

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Re: Alternative missions for BFR & MCT
« Reply #9 on: 09/14/2014 02:13 PM »
Depending on the exact EDL method selected, I suppose that MCT could also be used to ferry crew and cargo to a lunar surface facility.

If BFR/Falcon-XX/Condor (my name for it) is in the SLS's 130t IMLEO class, it is also a bog-standard heavy lifter but with a reusable core. It could therefore massively reduce the cost of building ISS- and Skywalker-sized space platforms.
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Offline llanitedave

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Re: Alternative missions for BFR & MCT
« Reply #10 on: 09/14/2014 03:58 PM »

So let's sound off and debate just what we think the MCT and BFR will be used for besides going to Mars.

Not so much a "debate" as simply an exchange of views.  "Debate" implies that there is a single answer or position that's worthy than others, and you win or lose by taking it.  There are lots of possible and worthwhile missions for a big enough and cheap enough launcher.

My own preference, and I don't expect it to be widely shared, (in addition to an eventual program of asteroid colonization), would be a solar-system wide constellation of 8m-class optical telescopes networked to form a giant multi-source optical interferometer.  Getting a 6 a.u. or so baseline would allow us to map just about every star and planet in the galaxy down to a gnat's butt.

Why would we want to do that?  That's a different debate.
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Offline Burninate

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Re: Alternative missions for BFR & MCT
« Reply #11 on: 09/14/2014 05:04 PM »
A ~300 ton BFR would probably not be used to lift 70-100 ton BA-2100's.  The BA-2100 is a Powerpoint-stage concept based on Bigelow's research into the largest feasible private-sector rocket.  A rocket 4x as large, with a 15m payload fairing, would engender a new design, likely a design with ~10x as much habitable volume.
« Last Edit: 09/14/2014 05:10 PM by Burninate »

Offline Nindalf

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Re: Alternative missions for BFR & MCT
« Reply #12 on: 09/14/2014 06:01 PM »
One can imagine a Lagrange Express, which makes regular deliveries to one or more lagrange point stations.  Just a regular schedule of flights to a destination without launch windows to worry about, and which isn't cluttered with high-energy space junk.

With diverse cargo and passengers headed to a variety of destinations, a lagrange point makes a logical place to unload/transfer.  It's reasonably good for the Moon, GEO, BEO, a large variety of clean, quiet Earth orbits suitable for labs and factories (particularly for processing of captured asteroids into useful materials), and with aerobraking, it's not terrible for LEO (you can hit any LEO orbit of your choice at approximately the same cost).

Assuming the LEO satellite market becomes a niche industry, it may make more sense to build aerobraking vehicles to be able to hit all of the target orbits than to fly individual launches.  Based on modified passenger capsule designs, these could even be reusable.

Another windowless regular target could be an equatorial LEO station, for all the things that just need to be in space for whatever reason, or which can get where they're going by ion thruster and patience.

Offline jsgirald

Re: Alternative missions for BFR & MCT
« Reply #13 on: 09/14/2014 06:08 PM »
The key question, as usual, is how much would cost to operate BFR. It should be easier and cheaper to service and handle a single core 9 engine stage than the three cores/27 engines of FH.

Yes I know, the hardware itself will be more expensive, but with reusability nailed down they could manage to bring costs per launch to a level comparable with today's F9. And if they don't get loads to fill a launch they may use the extra capacity to begin stockpiling fuel and hardware in orbit for their future Mars infrastructure.

IF they can make that, then SpaceX might become Fedex IN SPAAACE!
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Offline geza

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Re: Alternative missions for BFR & MCT
« Reply #14 on: 09/14/2014 07:08 PM »
My own preference, and I don't expect it to be widely shared, (in addition to an eventual program of asteroid colonization), would be a solar-system wide constellation of 8m-class optical telescopes networked to form a giant multi-source optical interferometer.  Getting a 6 a.u. or so baseline would allow us to map just about every star and planet in the galaxy down to a gnat's butt.
I like this very much! Of course, I also want a significantly sized submersible to be lowered into the ocean of Europa with sample return. Unfortunately, such projects are prohibitively expensive today even without launch cost. Probably we need an Elon v. 2 to revolutionize production methods for space probes and space telescopes!
« Last Edit: 09/14/2014 07:12 PM by geza »

Online Robotbeat

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Re: Alternative missions for BFR & MCT
« Reply #15 on: 09/14/2014 07:37 PM »
Without a big enough actual collecting area, a huge aperture size only helps for extremely bright sources, like blackhole accretion disks, etc. Ain't no such thing as a free lunch...
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Offline Vultur

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Re: Alternative missions for BFR & MCT
« Reply #16 on: 09/14/2014 10:56 PM »

Maybe propellant shipments for moving asteroids around for Planetary Resources type operations.

There's the perennial favourite of orbital solar-power; though all studies to date show you get more (even 24-hour) power for the same money with ground-based solar, so far as I know none of these have taken reusable launchers and the concomitant reduction of launch costs into account.

Also, the lack of winds etc. may allow thinner solar panels to be used. Has anybody done a solar power satellite study assuming 25 um thick panels (that's what IKAROS uses)? 

Assuming the density is about 2 g/cm^3 that's about 20,000 square meters per metric ton (for the panels alone, not the power wires/cables or the transmitter...) At 10% efficiency and Earth's distance from the sun that 20,000 square meters would produce about 2.7 megawatts* (though I don't know how efficient the transmission to Earth would be).

And you might be able to go even thinner than that.


Probably we need an Elon v. 2 to revolutionize production methods for space probes and space telescopes!

I think that will be a result of cheaper launch costs - right now the launch is a significant part of the cost of a "cheap" science mission (especially since they aren't launching them on Falcon 9).  If you could make it $10 million in exchange for much less reliability, that may not be worth it if the launch is $100 million plus.

But if the launches were much cheaper... you might be able to make 3 cheaper spacecraft  instead of 1 more reliable one, and make up for lack of reliability with redundancy (send 3 copies of the same probe).

As launches get cheaper the "cubesat"/smartphone electronics 'cheap' satellite mentality will be applied to bigger and more capable spacecraft, at some point overlapping with at least the lower end of 'official' science spacecraft (Discovery class etc.)

Online TrueBlueWitt

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Re: Alternative missions for BFR & MCT
« Reply #17 on: 09/14/2014 11:07 PM »

Maybe propellant shipments for moving asteroids around for Planetary Resources type operations.

There's the perennial favourite of orbital solar-power; though all studies to date show you get more (even 24-hour) power for the same money with ground-based solar, so far as I know none of these have taken reusable launchers and the concomitant reduction of launch costs into account.

Also, the lack of winds etc. may allow thinner solar panels to be used. Has anybody done a solar power satellite study assuming 25 um thick panels (that's what IKAROS uses)? 

Assuming the density is about 2 g/cm^3 that's about 20,000 square meters per metric ton (for the panels alone, not the power wires/cables or the transmitter...) At 10% efficiency and Earth's distance from the sun that 20,000 square meters would produce about 2.7 megawatts* (though I don't know how efficient the transmission to Earth would be).

And you might be able to go even thinner than that.


I can't believe DoD hasn't jumped on Space based Beamed solar power.. Seems like perfect way to get power to remote 3rd world outposts in places like Afghanistan and greatly reduce need for dangerous and expensive deliveries of Diesel Fuel.  Also could be helpful for disaster relief efforts around the globe.
« Last Edit: 09/14/2014 11:13 PM by TrueBlueWitt »

Offline llanitedave

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Re: Alternative missions for BFR & MCT
« Reply #18 on: 09/14/2014 11:23 PM »
Without a big enough actual collecting area, a huge aperture size only helps for extremely bright sources, like blackhole accretion disks, etc. Ain't no such thing as a free lunch...

True enough.  However, an added advantage of deep-space viewing is the ability to collect photons for hours or days on end without interruption.  An 8 meter mirror could probably be launched monolithically within a BFR fairing.  The technology for spincasting lightweight 8 meter mirrors is mature and reliable.  A single 8 meter mirror has over 11 times the collecting area of the Hubble Space Telescope.  A hexagon of six such mirrors would have over 66 times the light-gathering power.  With an interferometer network, the number of these mirrors could be increased as desired.

The distance between the mirrors can be as great as  technology allows.  I know that optical interferometry is difficult, and whether it will ever scale to a.u. distances I don't know.  But the larger you go, the greater the resolving power will be.  The viewing possibilities are mind-boggling.

A similar thing could be done with radio telescopes, which are easier to adapt to long-distance interferometry.  And having much more forgiving mechanical tolerances, the size of individual units would not be limited to 8 meters.  Rolled mesh parabolas hundreds of meters in diameter are most likely possible.
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Offline Jim

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Re: Alternative missions for BFR & MCT
« Reply #19 on: 09/15/2014 12:09 AM »
Probably we need an Elon v. 2 to revolutionize production methods for space probes and space telescopes!


We can stop with this type of nonsense

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