BFR concepts and ideas thread.

[YNM]

5 hours ago, magnemoe said:

Myself thinking of doing satellite launches with the manned BFR, especially for polar orbits there the satellites tend to be pretty small, bring along tourists for the run and an day in orbit. 

Yeah, but it'd be like when Shuttle only loft small 1000 kg satellites. Not very effective compared to using up the volume for things that do need space. And BFS has a lot of space... They could even test the systems that they'll eventually use for mars and moon exploration, at a site farther away than LEO.

Edited October 25, 2018 by YNM

[tater]

I think test flights of a crew version might well co-manifest sats. That said, SpaceX will have their own days that need launching. Thousands of them. Note that with a big launcher and low launch cost, the size can be dictated by what they think is optimal. I suppose they’d also want to launch, maneuver, launch, etc. if the sats are polar, all they have to do is raise apogee, let earth rotate under them x minutes, then drop apogee, and deploy more. No expensive plane changes required.

[mikegarrison]

On 10/19/2018 at 12:11 AM, satnet said:

Room - The Space Journal had an article recently about using algae that was pretty good (sorry, no free link as far as I know). In the short term it is probably a good avenue since (at least according to the article):

1. Algae are more efficient photosynthesizers than multi-cellular plants.

2. They can generate biomass very quickly.

3. They don't have a lot of dependencies in their life cycle.

4. They are single celled and don't really care about microgravity.

The downside is that while we can eat it, to really get nutrition out of it you humans need help from supplemental enzymes. Also they don't exactly meet most people culinary expectations. Still if they were providing oxygen and supplementing pre-packaged food, algae might be a good interim step towards a closed loop.

Reminds me of the Lois Bujold novel Ethan Of Athos which takes place on a space habitat. The main work of refreshing the atmosphere is done by specially tailored algae.  Then in order to get rid of the algae, it is fed to specially tailored newts. And the newts are in turn eaten as food. Visitors love all the different ways the newts are prepared as food, but all the stationers are extremely tired of eating newt.

[wumpus]

1 hour ago, mikegarrison said:

Reminds me of the Lois Bujold novel Ethan Of Athos which takes place on a space habitat. The main work of refreshing the atmosphere is done by specially tailored algae.  Then in order to get rid of the algae, it is fed to specially tailored newts. And the newts are in turn eaten as food. Visitors love all the different ways the newts are prepared as food, but all the stationers are extremely tired of eating newt.

If you have enough newts, you can feed them to something you want to eat.  The obvious first choice would be chickens, but I'm not all that sure if chickens would eat newt either (you might get them to eat algae as well).  Some sort of alligator might be better, presumably the growth/food of reptiles should be better than birds or mammal livestock, at least after enough breeding generations to match modern domestic animals.  Then again, I'm not sure the people of Bujold's worlds (outside of Jackson's Whole and Baryar) are all that approving of carnivorous diets.

[mikegarrison]

12 minutes ago, wumpus said:

If you have enough newts, you can feed them to something you want to eat.  The obvious first choice would be chickens, but I'm not all that sure if chickens would eat newt either (you might get them to eat algae as well).  Some sort of alligator might be better, presumably the growth/food of reptiles should be better than birds or mammal livestock, at least after enough breeding generations to match modern domestic animals.  Then again, I'm not sure the people of Bujold's worlds (outside of Jackson's Whole and Baryar) are all that approving of carnivorous diets.

The running joke was that the newts were actually pretty tasty; it's just that the station dwellers got really, really tired of them when they were served at almost every meal. This was only her second novel, and I'm not sure she had yet developed the idea that the more advanced places had "protein vats" that could grow just about about any meat you wanted without it being attached to an actual animal.

Edited October 26, 2018 by mikegarrison

[YNM]

11 minutes ago, wumpus said:

If you have enough newts, you can feed them to something you want to eat.

The higher up the foodchain you go, the more loss they generate.

idk, I seriously think a larger spacelab on BFR can answer them... if they really want to beef up their space game that is.

[wumpus]

Just now, YNM said:

The higher up the foodchain you go, the more loss they generate.

idk, I seriously think a larger spacelab on BFR can answer them... if they really want to beef up their space game that is.

I forgot the context of the fictional work I was referencing.  If you are teraforming a planet, you will have an unlimited supply of newts.  If you have a small Mars base or space station, your newt supply is limited.  I didn't think the newts were all that limited in the reference work.  I'm guessing that they did feed a few "premium" animals, but the locals still got the bulk of their calories from newts.

Any guesses on the amount of calories of corn consumed by Americans?  I guess most of it goes to animal feed or high fructose corn syrup, because you see plenty of corn farms but only eat a small portion of it is directly eaten (on the cob or canned).  I guess we got sick of corn as well.

[kerbiloid]

Why grow a whole newt. Grow just its tail.

[MinimumSky5]

Newts are a weird choice, sardines, or herring, or any other filter feeding fish surely would be more palatable. 

[YNM]

1 hour ago, wumpus said:

If you are teraforming a planet, you will have an unlimited supply of newts.

You still have a limited supply of energy. Which means limited supply of algae. Which means limited supply of "newts".

 

Anyway, yeah, I wonder whether SpaceX will test their colony systems on the BFR in spacelab-style missions.

[kerbiloid]

From newtonian physics to newtonian culinary.

[MinimumSky5]

24 minutes ago, kerbiloid said:

From newtonian physics to newtonian culinary.

Can we just stop and admire this pun! 

[NSEP]

On 10/26/2018 at 6:12 PM, YNM said:

Anyway, yeah, I wonder whether SpaceX will test their colony systems on the BFR in spacelab-style missions.

Speaking of spacelab, i wonder if there will be a hybrid cargo/crew version of BFR, kind of like the space shuttle, with 1/3 of the total volume pressurized and the other 2/3 unpressurized.

[Xd the great]

4 hours ago, NSEP said:

Speaking of spacelab, i wonder if there will be a hybrid cargo/crew version of BFR, kind of like the space shuttle, with 1/3 of the total volume pressurized and the other 2/3 unpressurized.

The fuselage will be a giant fuel tank, but there are cargo bays near the engines.

[kerbiloid]

Spoiler

4 hours ago, Xd the great said:

The fuselage will be a giant fuel tank, but there are cargo bays near the engines.

Why separate?

 

[NSEP]

Now that BFR has an aft cargo bay, maybe they can put a VASMIR/Ion engine in the aft cargo bay to reach other worlds with less amount of fuel?

[MinimumSky5]

That would take decades, or need a much, much more powerful power source than what BFR has available now. 

Would you want to fly in a BFR with a small nuclear reactor meters from your cabin? 

[tater]

5 hours ago, NSEP said:

Now that BFR has an aft cargo bay, maybe they can put a VASMIR/Ion engine in the aft cargo bay to reach other worlds with less amount of fuel?

All they need is is a 5-10 MWe nuclear reactor.

[NSEP]

Hmmm.

Maybe they could make a seperate module that would have the nuclear reactor radiation shielding, engines and fuel in place. It would be hard and expensive to do, and most certainly not in the near future, but they could theoretically reach nearly anywhere in to solar system in just 2 or more launches. Maybe its better to just stick with chemical fuels, but its just an idea, that's what this thread is for, after all.

[tater]

1 hour ago, NSEP said:

Hmmm.

Maybe they could make a seperate module that would have the nuclear reactor radiation shielding, engines and fuel in place. It would be hard and expensive to do, and most certainly not in the near future, but they could theoretically reach nearly anywhere in to solar system in just 2 or more launches. Maybe its better to just stick with chemical fuels, but its just an idea, that's what this thread is for, after all.

One thing that is possible/interesting, is that tail to tail docking for refilling operations means that they could theoretically make a "tug" unit that they could dock on the back that has ion engines, and perhaps additional solar panels. For lunar cargo, for example, you send the cargo version, refill it enough for landing on the Moon, and return and landing on Earth, then send it as a slow boat to LLO with ion engines. With a couple hundred tons of props, such a tug could drag a full cargo Starship to LLO, then return to LEO for reuse (propulsively, can be lighter if it aerobrakes).

[NSEP]

2 hours ago, tater said:

One thing that is possible/interesting, is that tail to tail docking for refilling operations means that they could theoretically make a "tug" unit that they could dock on the back that has ion engines, and perhaps additional solar panels. For lunar cargo, for example, you send the cargo version, refill it enough for landing on the Moon, and return and landing on Earth, then send it as a slow boat to LLO with ion engines. With a couple hundred tons of props, such a tug could drag a full cargo Starship to LLO, then return to LEO for reuse (propulsively, can be lighter if it aerobrakes).

Thats an idea interesting indeed.

I thought having some sort VASMIR/Ion of tug that is launched and deployed in orbit, maybe more than one launches. Then multiple Starships (fueled for orbital insertion/landing/launch) would dock to it and be carried to a target destination, so they could launch like, 3 Starships at a time to another world, without needing to launch and reuse the tanker 30 times.

If this thing would go to say, Mars, it would slowly do the transfer burn to Mars, then deploy the Starships while flying by Mars, then aerocapture it at Mars so it could also be used for departure. Aerobraking would be done when the Starships have already released. The same process would be for return to Earth.

[MinimumSky5]

The problem with these ideas is that the business plan for the BFR requires large launch cadences, to spread the lifetime cost of the system out. The idea of an ion powered lunar tug simply will not work, as SpaceX could launch many, many flights to the moon with a fleet of Starships in the same time as one ion powered Starship would take to get there. Also, the costs of developing such a module would be very large, even for SpaceX (who, to be fair, seem to be able to develop new systems very cheaply).

[mikegarrison]

6 minutes ago, MinimumSky5 said:

The problem with these ideas is that the business plan for the BFR requires large launch cadences, to spread the lifetime cost of the system out. The idea of an ion powered lunar tug simply will not work, as SpaceX could launch many, many flights to the moon with a fleet of Starships in the same time as one ion powered Starship would take to get there. Also, the costs of developing such a module would be very large, even for SpaceX (who, to be fair, seem to be able to develop new systems very cheaply).

Let's not get confused here.

Launching a rocket will always be more expensive than not launching a rocket. Reusability and high launch cadences only pay off if each launch is being paid for. It's not like extra launches magically make money if there is no customer.

[MinimumSky5]

True, but developing a tug of that design is also very expensive, and surely not worth the effort, if BFR is cheap to launch. 

But your right, I didn't explain myself there well.

[kerbiloid]

(Just a note: that's VASIMR)