BFS - the Human Factors - Updates and Discussion

[Johnnyhinbos]

There's a lot of excitement and anticipation surrounding Elon's IAC 2017 presentation and the future that it brightly paints. And from that excitement streams a nearly endless string of posts that use words such as "simply" and "just", as if developing the BFR/BFS is "simply" an exercise of scale with respect to the F9/HF.

I have every faith we _will_ see this bird fly, and potentially even in the time frame Elon hopes it will. However I thought perhaps it's a good time to start a thread dedicated to the parts of the equation SpaceX has no real experience in, and one that is of absolute critical importance to the success of the BFS - that of human life support and sustainability.

No SpaceX vehicle has ever had to support a human in space. Look how long it's taken to develop a flight suit, or to get Dragon 2 human rated for LEO missions to the LSS. And really, that's the low hanging fruit. What about long term ECLSS, a system that's closed loop rather than an open one? Or what about an EVA suit to deal with an emergency - because I don't care how much people say the crew on one of these ships will really just be passengers, Murphy and his law don't care and this ability must exist on long duration missions. What about the plumbing systems, electrical systems, black and grey water holding / treatment discharge systems. What about access to these systems during a mission? The list goes on and on...

I know various aspects of this have been discussed on this site in the past, but I think people sometimes forget that pushing a satellite into space (even deep space) is really only a fraction of what needs to be addressed when it comes to launching humans.

I've not seen very much "intel" with regards to how SpaceX intends to deal with all this - but it will take a huge amount of resources - and of time and money - to develop and now the clock is ticking.

Let's consolidate our thoughts and pertinent into this thread so we can keep our finger on the pulse of this side of BFS development (pun intended...)

[Oersted]

15 years of ISS operations have given us a huge knowledge base about what to do and what NOT to do. It will be a challenge but I don't think it will be long pole in the tent. Especially since there is bound to be a lot of shakedown flights in Earth orbit and going to the Moon before manned BFR's head to Mars.

[DreamyPickle]

Isn't the ISS ECLSS system known for having somewhat frequent breakdowns? Such issues would be harder to deal with on the BFS because it has to operate at a significant light-lag from ground-based experts and emergencies are potentially catastrophic.

The primary goal should be reliability, even at the expense of efficiency. After it lands the plan is to collect very large amounts of water anyway so very long term closed-loop operations are less interesting than for a space-station.

It seems very likely that this will be something that SpaceX contracts out at least partially. It's not really important for their competitive position and having companies around that can provide such systems would help attempts at commercial habitats which means more launch business.

[rakaydos]

Isn't the ISS ECLSS system known for having somewhat frequent breakdowns? Such issues would be harder to deal with on the BFS because it has to operate at a significant light-lag from ground-based experts and emergencies are potentially catastrophic.

The primary goal should be reliability, even at the expense of efficiency. After it lands the plan is to collect very large amounts of water anyway so very long term closed-loop operations are less interesting than for a space-station.

It seems very likely that this will be something that SpaceX contracts out at least partially. It's not really important for their competitive position and having companies around that can provide such systems would help attempts at commercial habitats which means more launch business.

It depends how important human eyes-on are for maintinance of the mars gas station. If transportation infrastructure (railroad coaling depots, gas stations, and now ISRU sites) depends on life support for reliable operation, SpaceX may bring life support technoligies in-house.

[DOCinCT]

To complicate the matter, facilities on the BFR Spaceship will have to operate in zero-G on the way to or from Mars and will have to operate, or be suitable for, the 0.4G gravity well on the surface of Mars. 

[dwheeler]

15 years of ISS operations have given us a huge knowledge base about what to do and what NOT to do. <snip>

Honest question:  Is this knowledge the type of thing NASA would share with SpaceX with no strings attached?

[Negan]

There's no way they could rely on the ISS alone. They will have to be clever on a lot of thing especially related to cost. No way can they spend 19 million buying a toilet from the Russians.

[envy887]

15 years of ISS operations have given us a huge knowledge base about what to do and what NOT to do. <snip>

Honest question:  Is this knowledge the type of thing NASA would share with SpaceX with no strings attached?

That is the purpose of NASA.

[Ludus]

To complicate the matter, facilities on the BFR Spaceship will have to operate in zero-G on the way to or from Mars and will have to operate, or be suitable for, the 0.4G gravity well on the surface of Mars.

SpaceX hasn’t said much about it but the new BFS design that can lock base to base for propellant transfer would make a pretty cool rotating ship pair so maybe it won’t have to operate in zero-G on trips to Mars. It’s smart to send ships in pairs anyway.

[Negan]

To complicate the matter, facilities on the BFR Spaceship will have to operate in zero-G on the way to or from Mars and will have to operate, or be suitable for, the 0.4G gravity well on the surface of Mars.

SpaceX hasn’t said much about it but the new BFS design that can lock base to base for propellant transfer would make a pretty cool rotating ship pair so maybe it won’t have to operate in zero-G on trips to Mars. It’s smart to send ships in pairs anyway.

They might get lucky working with the 9m diameter they already have. I wouldn't be surprised to see them experiment with that first if they're interested in AG at all.

[darkenfast]

There has never been any indication that BFR will attempt spin-gravity.  The loads would require a lot more mass added to the ships, and it seems that Musk would rather spend that mass on fuel to reduce travel time.  This topic has been hashed out on this forum before.

[guckyfan]

SpaceX hasn’t said much about it but the new BFS design that can lock base to base for propellant transfer would make a pretty cool rotating ship pair so maybe it won’t have to operate in zero-G on trips to Mars. It’s smart to send ships in pairs anyway.

That would give gravity in the opposite direction compared to the landed and accelerated states.

[su27k]

To complicate the matter, facilities on the BFR Spaceship will have to operate in zero-G on the way to or from Mars and will have to operate, or be suitable for, the 0.4G gravity well on the surface of Mars.

I think this would be true for any facilities on current spacecraft, since you'll need to test it on Earth so it needs to work in 1G.

[Negan]

There has never been any indication that BFR will attempt spin-gravity.  The loads would require a lot more mass added to the ships, and it seems that Musk would rather spend that mass on fuel to reduce travel time.  This topic has been hashed out on this forum before.

Doesn't it have to handle multiple g loads when launching and landing on Earth and Mars (not just once but hundreds of times)? Hard to believe that spinning it up to probably less than .5g would be any problem.

[darkenfast]

There has never been any indication that BFR will attempt spin-gravity.  The loads would require a lot more mass added to the ships, and it seems that Musk would rather spend that mass on fuel to reduce travel time.  This topic has been hashed out on this forum before.

Doesn't it have to handle multiple g loads when launching and landing on Earth and Mars (not just once but hundreds of times)? Hard to believe that spinning it up to probably less than .5g would be any problem.

Any time you change the direction of loads, it makes a difference in how you design your structure.  Think of the difference in how it feels when you stand on a surface versus hanging suspended by your wrists. If you go tail-to-tail you've now added a third direction of loads: towards the tail in powered flight or standing on a surface, sideways for re-entry, and towards the nose when rotating.  Communications is more difficult, plumbing becomes a nightmare, and the interior needs to convert.  If you go nose-to-nose, you need a tether of some sort, which adds the new complication of keeping everything stable, not to mention the fact that the vehicle has probably not been designed to hang by its nose. 

If and when we venture into the outer Solar System on multi-year voyages, we will probably need some sort of spin gravity.  For the flight times that Musk predicts for the BFR to Mars, it simply isn't necessary.

[Ludus]

There has never been any indication that BFR will attempt spin-gravity.  The loads would require a lot more mass added to the ships, and it seems that Musk would rather spend that mass on fuel to reduce travel time.  This topic has been hashed out on this forum before.

Doesn't it have to handle multiple g loads when launching and landing on Earth and Mars (not just once but hundreds of times)? Hard to believe that spinning it up to probably less than .5g would be any problem.

No indication they will. It just seems interesting. Locked base to base the way they’re designed for propellant loading the ships are about 100m long. A spin rate of 2 rpm considered within optimal would give around .2 g so somewhat more than the moon or half Mars. Yes couches would have to be flipped in orientation from launch/landing to AG mode but that’s probably not so difficult in zero g manually. I really have no expertise but it seems implausible that a ship designed for multiple g stresses repeatedly can’t handle a gentle .2 g spin for AG.

Not that I’m talking about a tether, but actually the BFS HAS been designed to hang by it’s nose. It gets lifted by the hammerhead crane on the pad into place on the BFR.

[douglas100]

Apart from the load paths, the current design doesn't provide for constant rotation. The solar panels couldn't track the sun, for example.

[Negan]

Any time you change the direction of loads, it makes a difference in how you design your structure.

There's going to be some inherent load capacity no matter what direction. That's the cool thing about being able to adjust gravity between 0 and 1g with the rpm, but I do get what you're saying. Maybe the loads are so low no structurally safe amount of AG will work.

[Ludus]

Apart from the load paths, the current design doesn't provide for constant rotation. The solar panels couldn't track the sun, for example.

That’s a good point. It would mess with the efficiency of the solar panels.

[guckyfan]

Apart from the load paths, the current design doesn't provide for constant rotation. The solar panels couldn't track the sun, for example.

Going to Mars does not need and will not have AG, I am very confident to say. Going outward from Mars will need nuclear power. If not during cruise time for the crew, then for fuel ISRU at the destination. Heat rejection will then need to be constructed for spin gravity. Very low gravity, it can be near the center. Joining at the engine side has the advantage that the habitable space is most distant from center.

[DreamyPickle]

People can survive several months in zero-G just fine, this was proven on Mir and ISS several hundred times. At most the crew will be a little out-of-shape when they land but being the first on the surface of a new planet should provide a sufficient adrenaline shot. And they can rest a while until the crane is checked out.

It would be great to have medical data from living for long durations in low gravity but the risk of something going wrong seems very low. SpaceX doesn't have a good reason to invest resources in this.

[corneliussulla]

It seem likely to me that the first 2 crewed ships will probably have crews of 10-12 in size. Probably 1 specialist of each type on each crew. For instance 1 doctor on each crew etc. They need to have plans to cover loss of crew during flight/EDL and during the mission.

 So with that size crew I would think the life support systems used on the ISS would be a good starting point. No need to build the first few ships with life support systems for 120 people. Those crew sizes are probably in the 2030 and beyond time period and as the ships are coming directly back to earth they can be retro fitted.

[console65]

It seem likely to me that the first 2 crewed ships will probably have crews of 10-12 in size. Probably 1 specialist of each type on each crew. For instance 1 doctor on each crew etc. They need to have plans to cover loss of crew during flight/EDL and during the mission.

I would think it would be double that number.  There should be skill redundancy for such a long duration mission far from any sort of help.  Yes, technically there would be two doctors, and pairs of other such specialists, on the mission but it would be one specialist on each ship and if, God forbid, something were to happen to one of the ships...

[speedevil]

Apart from the load paths, the current design doesn't provide for constant rotation. The solar panels couldn't track the sun, for example.

The solar panels could easily track the sun if you orient them parallel to the ships wings, and have the rotation around an axis in parallel with a line pointing 'up' from the wings towards the sun.

With a small counterweight, it both could track the sun, and the load paths do not change.
Assuming for the moment there is a nose-hook which can take 100 tons or so for lifting, placing a counterweight so it can rotate will allow you to have ~1m/s^2 acceleration, or ~0.1g. 0.1G.
As rotational acceleration = velocity squared divided by radius. A=V^2/r -> 1=V^2/r -> r=V^2 -

So, at 100m/s, radius is 10km, with a ten minute period - probably a bit excessive. 20m/s gives 400m radius, 120 second.
With a 4.4km tether, that'd be around a ten ton counterweight.

It would be moderately expensive unless you have some use for the weight on Mars.

(I am not of course saying that this is what they should do, and it does add a complication)

[biosehnsucht]

It seem likely to me that the first 2 crewed ships will probably have crews of 10-12 in size. Probably 1 specialist of each type on each crew. For instance 1 doctor on each crew etc. They need to have plans to cover loss of crew during flight/EDL and during the mission.

I would think it would be double that number.  There should be skill redundancy for such a long duration mission far from any sort of help.  Yes, technically there would be two doctors, and pairs of other such specialists, on the mission but it would be one specialist on each ship and if, God forbid, something were to happen to one of the ships...

I imagine you'd just have a bunch of people who are multi-specialists. At least two people who are "full medical doctors" on each ship, capable of dealing with ANYTHING that could happen that could be dealt with (i.e., no need for brain surgeons or transplant surgeons, but there's still a wide array of things you might need to deal with), and most of the rest would have basic medical training like you'd see for ordinary military personnel (bandages, splints, etc).

Similarly, you'd have overlapping "mission specialists" such as two  or more people trained in all the intricacies of the ISRU equipment, others in the power systems, ECLSS, etc, such that everyone knows at least two things really well and knows enough about the rest to follow orders from those that do (or use a manual). There may not be time to wait for instructions from Houston, after all. Just make sure that at least two people know enough about each thing that either might need to be fixed (and could be - if it can't possibly be fixed outside of Earth, no need to worry about it) or put together / set up on Mars.

This isn't just about redundancy of knowledge for survival either, you might really need two or more people of a given specialty to fix or set up certain things.

[CuddlyRocket]

15 years of ISS operations have given us a huge knowledge base about what to do and what NOT to do.

Isn't the ISS ECLSS system known for having somewhat frequent breakdowns? Such issues would be harder to deal with on the BFS because it has to operate at a significant light-lag from ground-based experts and emergencies are potentially catastrophic.

The primary goal should be reliability, even at the expense of efficiency. After it lands the plan is to collect very large amounts of water anyway so very long term closed-loop operations are less interesting than for a space-station.

I think a lot of the problems and expense of the ISS ECLSS are due to various restrictions on resources that it has had to be designed to cope with - namely: volume, mass, power and amount of human intervention. With BFR as designed, all of those (except possibly the power) will be a lot less restrictive. Most notably the amount of human intervention available. The ISS is designed to run as autonomously as possible as the crew has lots of other things to do. With many BFR missions, the problem will be finding something for them to do!

[Johnnyhinbos]

Astronaut Chris Hadfield’s balanced reaction to Elon’s 2017 BFR presentation, which also touches on human factors issues...

[Johnnyhinbos]

There's an interesting bit of conversation that's germane to the human factors component over on the "Re: IAC 2017 -- BFR v0.2 - DISCUSSION THREAD 3 (Post Speech)" thread. I'm hoping to get the conversation moved over to this thread in order to keep the conversation going...

https://forum.nasaspaceflight.com/index.php?topic=43920.msg1734192#msg1734192