Draft and Final RFP for Gateway logistics/cargo services

[JEF_300]

With SpaceX being as focused on Starship and Mars as it is, I wouldn't be totally surprised if they passed on this altogether.

Exactly.  Turn the question around: Why would SpaceX bother with this distraction?  Only reasons I can think of is if they are hard up for cash (or related) in need of accessible tech being developed as part of the program.  Both of which are doubtful reasons IMO.

SpaceX is *always* hard-up for cash.

It's the height of idiocy to write requirements in a way that inflexibly excludes your best existing solutions while not allowing large future capability as well. It's repeating some of NASA's past mistakes excluding EELVs.


...not to mention NASA'S BASELINE FULLY FUELED LANDER STACK WILL WEIGH MORE THAN 14 TONS DOCKED.

So a lot of stuff will be docking with the Gateway. The Gateway's PPE could at one point have to control, all at once:

~20t of Gateway
<25t of Orion
>14t of lander
   ??t of logistics craft

Now maybe, just maybe, one of the hundreds of smart engineers at NASA thought of that.

Maybe the 14-ton limit being proposed for the Logistics Craft didn't come out of thin air, but actually from the limits of the Gateway's control system when it is at max capacity.

Maybe 14-tons isn't a number picked out to exclude Starship, but just the number you get when you subtract the mass of the hab, Orion, and assembled lander from the mass that the PPE can manage.

Or, ya know, maybe you're right.

[Robotbeat]

With SpaceX being as focused on Starship and Mars as it is, I wouldn't be totally surprised if they passed on this altogether.

Exactly.  Turn the question around: Why would SpaceX bother with this distraction?  Only reasons I can think of is if they are hard up for cash (or related) in need of accessible tech being developed as part of the program.  Both of which are doubtful reasons IMO.

SpaceX is *always* hard-up for cash.

It's the height of idiocy to write requirements in a way that inflexibly excludes your best existing solutions while not allowing large future capability as well. It's repeating some of NASA's past mistakes excluding EELVs.


...not to mention NASA'S BASELINE FULLY FUELED LANDER STACK WILL WEIGH MORE THAN 14 TONS DOCKED.

So a lot of stuff will be docking with the Gateway. The Gateway's PPE could at one point have to control, all at once:

~20t of Gateway
<25t of Orion
>14t of lander
   ??t of logistics craft

Now maybe, just maybe, one of the hundreds of smart engineers at NASA thought of that.

Maybe the 14-ton limit being proposed for the Logistics Craft didn't come out of thin air, but actually from the limits of the Gateway's control system when it is at max capacity.

Maybe 14-tons isn't a number picked out to exclude Starship, but just the number you get when you subtract the mass of the hab, Orion, and assembled lander from the mass that the PPE can manage.

Or, ya know, maybe you're right.

The limits of the gateway are not /hard/ limits.

These are "nice to haves" written as hard requirements. And yeah, I am right. The requirements didn't need to be written in this way.

[JEF_300]

With SpaceX being as focused on Starship and Mars as it is, I wouldn't be totally surprised if they passed on this altogether.

Exactly.  Turn the question around: Why would SpaceX bother with this distraction?  Only reasons I can think of is if they are hard up for cash (or related) in need of accessible tech being developed as part of the program.  Both of which are doubtful reasons IMO.

SpaceX is *always* hard-up for cash.

It's the height of idiocy to write requirements in a way that inflexibly excludes your best existing solutions while not allowing large future capability as well. It's repeating some of NASA's past mistakes excluding EELVs.


...not to mention NASA'S BASELINE FULLY FUELED LANDER STACK WILL WEIGH MORE THAN 14 TONS DOCKED.

So a lot of stuff will be docking with the Gateway. The Gateway's PPE could at one point have to control, all at once:

~20t of Gateway
<25t of Orion
>14t of lander
   ??t of logistics craft

Now maybe, just maybe, one of the hundreds of smart engineers at NASA thought of that.

Maybe the 14-ton limit being proposed for the Logistics Craft didn't come out of thin air, but actually from the limits of the Gateway's control system when it is at max capacity.

Maybe 14-tons isn't a number picked out to exclude Starship, but just the number you get when you subtract the mass of the hab, Orion, and assembled lander from the mass that the PPE can manage.

Or, ya know, maybe you're right.

The limits of the gateway are not /hard/ limits.

These are "nice to haves" written as hard requirements. And yeah, I am right. The requirements didn't need to be written in this way.

The problem is not that they arbitrarily decided while forging this one document to try to exclude Starship. The entire Artemis Program's architecture is exclusionary to Starship, likely unintentionally. If that's a problem for you, there are better places to discuss it.

[Robotbeat]

It is a problem, the same way that excluding EELVs was a problem.

[JohnFornaro]

Dragon is smaller than NASA really wanted for CRS, I don't see it being competitive for the Gateway missions without extensive mods (go expendable, ditch the heat shield, cut a hole in the bottom and put more pressurized space in a larger trunk?)

This should be a piece of cake for SpaceX. If not, they should give up going to Mars.

With SpaceX being as focused on Starship and Mars as it is, I wouldn't be totally surprised if they passed on this altogether.

In a way, that would be like starting to drive across Death Valley and not topping off your radiator or filling up the gas tank.

[woods170]

Dragon is smaller than NASA really wanted for CRS, I don't see it being competitive for the Gateway missions...

Emphasis mine.

With all due respect but that statement is not rooted in fact. NASA, under COTS/CRS-1 issued only two high-level requirements which had any effect on spacecraft size:
- Minimum amount of pressurized cargo to be transported up to ISS.
- Minimum amount of cargo missions to be flown.

NASA did not require the COTS contractors to have their spacecraft be of a minimum size/weight. Had NASA really wanted the contractors' spacecraft to be of a certain minimal size than they would have issued a requirement for it. But NASA didn't.

[speedevil]

In a way, that would be like starting to drive across Death Valley and not topping off your radiator or filling up the gas tank.

If the person topping off your radiator insists that your vehicle must only take liquid helium as a coolant, that might not be insane.

There is a wide spread of possible futures for SpaceX, varying from 'starship doesn't ever work' to the time beween SS being potentially biddable and the time it does its first lunar mission being too short to do it under the contract.

It would not always make sense for them to bid.

[jarmumd]

I do want to make a point about starship.  For all the people suggesting that Starship be used to dock to ISS or dock to gateway.  Starship can't dock to either.  Starship docking to ISS would likely require it to actively control itself after docking (so that ISS doesn't start to flip over wildly), not to mention it would likely need a new docking adapter sized for it. 

Gateway would have to dock to starship, which it doesn't have the control systems to do (thrusters, etc).  It's possible that you could use an arm to attach gateway to starship, but again, you would need starship to be under active control to maintain orientation/position. 

While neither of those cases is physically impossible, it would require a completely different operational control, which NASA likely won't do.

I could buy potentially using a module (lunar module, logistics module) as a go-between from gateway to starship.  Hopefully when all those elements exist, that can happen.  Would be a sight to see!

[brickmack]

I wonder if one of the PPE contractors will propose an Ion Cycler of some sort. Take your PPE design, have it pick up a pressurized cargo module and refuel in LEO, travel to the station over 3-6 months, and when it's done at the gateway, jettison the cargo module, return to LEO, and wait for a new shipment.

All of the Gateway PPE losing bidders are planning to propose this, though as I mentioned upthread it seems SNC is the only one with much of a shot (if any). Don't need to jettison the cargo module, a PPE-sized propulsion module can easily do a round-trip LEO-cislunar-LEO mission with a Cygnus PCM/Dream Chaser expendable module/similar without expending anything. Bringing the cargo module back allows return payload capacity (via docking at ISS and handing samples off to some crew/logistics vehicle there), and reduces hardware cost (not just the pressure vessel, but docking hardware as well), and probably wouldn't be a 1:1 mass savings anyway since there now need to be detachable reusable interfaces between those modules, and the pressure vessel can no longer be used as a structural element (as on SNC's PPE).

Transit time would probably be closer to 6 months each way than 3, based on previous studies of similarly-sized tugs with electric propulsion systems of comparable thrust and ISP. NASA requirement for the Gateway PPE was <100 days from launch to insertion at NRHO, but that was assuming a launch to at minimum a GTO-like trajectory, not starting in LEO. The first use of each unit could cut a lot of that outbound travel time out though, by launching directly to TLI (triple-reusable FH is easily big enough to throw any of the PPE concepts direct to TLI). So probably the first mission would be ~2 months from launch to first docking, then ~3 months at the Gateway for cargo transfer and whatever, ~6 months to return to LEO, 1 month at ISS for cargo transfer and refueling, ~6 months outbound, repeat.

[whitelancer64]

I do want to make a point about starship.  For all the people suggesting that Starship be used to dock to ISS or dock to gateway.  Starship can't dock to either.  Starship docking to ISS would likely require it to actively control itself after docking (so that ISS doesn't start to flip over wildly), not to mention it would likely need a new docking adapter sized for it. 

I'm uncertain what you mean by this paragraph. What's wrong with the docking system SpaceX already has?

Gateway would have to dock to starship, which it doesn't have the control systems to do (thrusters, etc).  It's possible that you could use an arm to attach gateway to starship, but again, you would need starship to be under active control to maintain orientation/position. 
*snip*

Gateway will have thrusters. Where are you getting the idea it wouldn't have thrusters?

[JEF_300]

I wonder if one of the PPE contractors will propose an Ion Cycler of some sort. Take your PPE design, have it pick up a pressurized cargo module and refuel in LEO, travel to the station over 3-6 months, and when it's done at the gateway, jettison the cargo module, return to LEO, and wait for a new shipment.

All of the Gateway PPE losing bidders are planning to propose this, though as I mentioned upthread it seems SNC is the only one with much of a shot (if any). Don't need to jettison the cargo module, a PPE-sized propulsion module can easily do a round-trip LEO-cislunar-LEO mission with a Cygnus PCM/Dream Chaser expendable module/similar without expending anything. Bringing the cargo module back allows return payload capacity (via docking at ISS and handing samples off to some crew/logistics vehicle there), and reduces hardware cost (not just the pressure vessel, but docking hardware as well), and probably wouldn't be a 1:1 mass savings anyway since there now need to be detachable reusable interfaces between those modules, and the pressure vessel can no longer be used as a structural element (as on SNC's PPE).

Transit time would probably be closer to 6 months each way than 3, based on previous studies of similarly-sized tugs with electric propulsion systems of comparable thrust and ISP. NASA requirement for the Gateway PPE was <100 days from launch to insertion at NRHO, but that was assuming a launch to at minimum a GTO-like trajectory, not starting in LEO. The first use of each unit could cut a lot of that outbound travel time out though, by launching directly to TLI (triple-reusable FH is easily big enough to throw any of the PPE concepts direct to TLI). So probably the first mission would be ~2 months from launch to first docking, then ~3 months at the Gateway for cargo transfer and whatever, ~6 months to return to LEO, 1 month at ISS for cargo transfer and refueling, ~6 months outbound, repeat.

I just said jettison the cargo module because I don't see how the new cargo would get into it. It's true that you could dock to ISS and have the crew transfer cargo, but that seems like a waste of astronaut time, and it seems less like providing NASA the service of moving cargo to Gateway if NASA employees (and a Cosmonaut or two for that matter) are doing part of the transport work. Seems easier to just jettison the pressurized module, and have a new one docked to it in LEO. Like a lunar shipping container.

[jarmumd]

I'm uncertain what you mean by this paragraph. What's wrong with the docking system SpaceX already has?

I should have been a bit more specific.  It's possible it could work, but the adapter was not intended for the mass of the Starship, there is literally an order of magnitude more energy to remove.  You have to think moment arm, the docking system is a very tiny moment arm trying to rotate the massive inertia of the Starship (think angular misalignment between the ISS and Starship).

Gateway will have thrusters. Where are you getting the idea it wouldn't have thrusters?

Well since it isn't designed yet, I've probably made a bad assumption, but the xenon thrusters on the PPE would not be suitable for a docking approach - they would be too low in force.  You would need larger thrusters like dracos.  Maybe it will have those.

[speedevil]

I do want to make a point about starship.  For all the people suggesting that Starship be used to dock to ISS or dock to gateway.  Starship can't dock to either.  Starship docking to ISS would likely require it to actively control itself after docking (so that ISS doesn't start to flip over wildly), not to mention it would likely need a new docking adapter sized for it. 

Development of a dragon-derived vehicle that shuttles between SS and whatever and does not ever need to do reentry or significant delta-v does not seem of a meaningfully comparable difficulty to getting SS working.

[Robotbeat]

I'm uncertain what you mean by this paragraph. What's wrong with the docking system SpaceX already has?

I should have been a bit more specific.  It's possible it could work, but the adapter was not intended for the mass of the Starship, there is literally an order of magnitude more energy to remove.  You have to think moment arm, the docking system is a very tiny moment arm trying to rotate the massive inertia of the Starship (think angular misalignment between the ISS and Starship).

Gateway will have thrusters. Where are you getting the idea it wouldn't have thrusters?

Well since it isn't designed yet, I've probably made a bad assumption, but the xenon thrusters on the PPE would not be suitable for a docking approach - they would be too low in force.  You would need larger thrusters like dracos.  Maybe it will have those.

ISS was docked to by the Shuttle, which is just as big as Starship. Even when ISS was teeny tiny.

[Khadgars]

Not really understanding why SS is being discussed here, its unlikely to be chosen in the unlikely event SpaceX even bids it, which I doubt they will.

Dragon-derived on the other hand is intriguing to me.

[jarmumd]

ISS was docked to by the Shuttle, which is just as big as Starship. Even when ISS was teeny tiny.

I thought empty, Starship is 50% more mass than shuttle (and much larger MOI due to it's length).  Full, starship isn't it 14x shuttle?

Sorry to lead this down a starship hole.  I'll stop.  I am really glad that NASA is continuing with commercial resupply, now to Gateway.

[whitelancer64]

Starship is bigger than the Shuttle but not by a lot.

[Robotbeat]

ISS was docked to by the Shuttle, which is just as big as Starship. Even when ISS was teeny tiny.

I thought empty, Starship is 50% more mass than shuttle (and much larger MOI due to it's length).

Shuttle on a full mission is over 100 tons (up to 135 tons when carrying Chandra). Starship, before the current downsize to a 20 engine first stage, was 85 tons dry. So they overlap. As far as being longer, that depends what the current resize of the booster means for Starship proper.

Full, starship isn't it 14x shuttle?

...not in this application.

[JEF_300]

It would be a little silly, but if SNC can make it meet the other requirements, they could propose using a Cargo Dreamchaser that's transported to Gateway and then back to LEO by their PPE. This would not only give them down-mass capability but soft-land as well, albeit with 6 months of transit. It's interesting at least.

[su27k]

Dragon is smaller than NASA really wanted for CRS, I don't see it being competitive for the Gateway missions...

Emphasis mine.

With all due respect but that statement is not rooted in fact. NASA, under COTS/CRS-1 issued only two high-level requirements which had any effect on spacecraft size:
- Minimum amount of pressurized cargo to be transported up to ISS.
- Minimum amount of cargo missions to be flown.

NASA did not require the COTS contractors to have their spacecraft be of a minimum size/weight. Had NASA really wanted the contractors' spacecraft to be of a certain minimal size than they would have issued a requirement for it. But NASA didn't.

I haven't read the new RFP closely, but it seems to me the above is true for Gateway cargo too, no specific requirement for minimal size of the spacecraft, so I don't see how Dragon can be uncompetitive when the size is not even in the requirement.