Commercial space's role in Exploration Gateway station

[Lar]

That said, commercial space can get things started ahead of EG by sending their own hardware to ISS. That hardware could eventually be moved to the EG. ISS and LEO is an obvious starting point and staging area for all operations, including commercial, that could eventually migrate into BEO.

Is the high inclination orbit ISS is in a drawback at all, though? I agree that it's a great place to stage in terms of the equipment, people and expertise already there. But how much delta V is wasted due to inclination changes needed?? I'm no orbital mechanic so forgive me if that's a not very well informed question.

[QuantumG]

Lost delta-v doesn't compare to the lost productivity of trying to do it without the ISS.

[Lar]

Lost delta-v doesn't compare to the lost productivity of trying to do it without the ISS.

True, even when propellant all comes from earth. But especially true if it's brought to LEO in tankers filled up by PRI operations... I suppose the topic of ISS's inclination has been beat to death elsewhere. But I'm a noob here, and there's so much to read here.

[jnc]

But how much delta V is wasted due to inclination changes needed??

Lots. See here for more, but for an example: "if the angular change is equal to 60 degrees, the required change in velocity is equal to the current velocity".

To see why, think about a 90 degree plane change. In rough terms, you have to kill the x-direction velocity completely, and take the y-direction velocity from 0 to orbital speed. (Actually, it's a bit more complex than that, but this gives a rough, intuitive sense for the magnitude needed.) That's 2 times the orbital velocity..

Noel

[Lobo]

On the Dragon's return press conference Alan Lindenmoyer did say something along the lines that they where considering SpaceX's help on explorations. It has been discussed here to death, if a Falcon Heavy could push a Dragon to EML2. And Dragon is going to get BEO upgrades. So it is possible for Dragon, to offer something along the lines of COTS for an EML2 Cargo Resupply. I'm not sure about Crew, because transit times might get too long for Crewed Dragon. But Cargo Dragon shouldn't be that far fetched. If they use ISS legacy modules and ops, the ISS Cargo Dragon would be a lot similar, so it would be ridiculous not to take advantage of all the work done. If they don't use CBM, and use NDS also for cargo, they could demonstrate an Robotic Orion/Cargo Dragon on EML2 even before the first module is there.
I do wonder, if this is a strategy that NASA will follow, if it won't impact on the Commercial Crew selection. I mean, it's quite clear that Dragon/Falcon Heavy is very close be able to do cargo to EML2. It's not very clear if they can do crew, but it is possible with some evolution. Since CST-100 evolved from the competition with Orion, I'm sure it could be upgraded to do cargo and/or crew with relatively little risk, but it would need a new launcher. Either a human rated Delta IV Heavy, an Atlas V Heavy or an Atlas Phase 2. Could obviously use Falcon Heavy, too, but I guess the idea would be not to have to rely on a single supplier, if possible.
Dream Chaser isn't designed for BEO, and I doubt it could be upgraded to tolerate a lunar reentry, so, in that sense, it would seem like a dead end to LEO.
I ignore the Blue Origin entry, but if they use the biconic side for reentry, it won't tolerate lunar reentry.
Liberty capsule could obviously do BEO very well, but I don't believe Liberty rocket can send it to EML2. So, in that sense, it could be a good candidate for the capsule's future, but the LV has not many growth options. Plus, the Vulcain 2 can't restart, which is probably a worse problem. And it's going to be a very thorny legal problem for LM to actually develop a BEO SM for Liberty without using Orion's systems, which require special legislation to be able to compete.
I do want to add, that given a powerful enough LV, Cygnus is probably able to do a cargo mission to EML2.
the problem with international partners, is that Ariane 5 and H-IIB can't push ATV and HTV beyond LEO, so it would mean a new capsule development or a new LV.
I don't know what the Angara 5 will be able to do, but I'm sure Soyuz LV can't be increased significantly, and to evolve Soyuz for EML2 would need something like launching an EDS on a Proton or Angara 5. Plus, they might want to use the PPTS.
In other words, the ISS partners are all very far from being able to do any logistics role to EML2.
In other words, from my perspective, if NASA expects to evolve commercial to EML2, Dragon, CST-100 and possibly Cygnus are the most likely candidates to support now.

(Note, some of this is from the commercial crew down select thread, as I posted it there before I saw this more applicable thread)

I think it depends on if it would be staffed year around, or only during a mission.  How much cargo that’s needed would depend on that.  Obviously all the crew rotation would be done by Orion on SLS.  SLS and Orion would be the only man-rated capsule and LV that could get out there, at first anyway.  And I think NASA would want to keep it that way for obvious reasons of justifying Orion and SLS for BLEO operations.  (I don't think they'd want some one to come along and do it faster and cheaper).

Now, SpaceX here is interesting.  If SpaceX gets a commercial crew contract, then F9 and Dragon will be man rated. Which means FH should basically be man-rated by default.  So SpaceX could then possibly offer a commercial crew service to EML2.  Dragon (or Dragonrider) should have the capability for that long in space.  Might need some upgrades like a bathroom, though.  NASA might be interested in that as a backup to SLS/Orion, but like I said, I doubt they’d want to have anything but SLS/Orion delivering crews out there, unless there was some problem and SLS/Orion was grounded. 

However, SpaceX with Dragon and FH would be in a very good position to offer cargo support to EML2.  FH could get a loaded cargo Dragon and trunk out there, and probably for a pretty reasonable price.  Maybe around 10mt of cargo? Both pressurized and unpressurized.   I understand that Dragon is designed to handle those reentry speeds anyway.  (at least Musk has said so I think) And with the trunk and solar panels, Dragon can operate for the trip out and trip back.
CST-100 on the other hand would need to be upgraded with a trunk and solar panels or fuel cells, because I understand it’s only designed for a few hours of battery life?  Just enough to get a crew to the ISS, and then to get them back home.  It’s batteries would die on the way out to EML2 if launched on an Atlass 551 or D4H.  I also don’t know if it’s heat shield could handle BLEO reentry speeds without being upgraded too.
I believe DC is incapable of BLEO reentry speeds, being a space plane (please correct if that’s wrong). 
I don’t know enough about Liberty to know if that LV could get a capsule out to EML2.  I understand it’s an LV more optimized for LEO operations, but I think they are advertising it can sent payloads to GTO, so maybe it could.  Be interesting to know how much cargo it could get out there on top of the CSM, if it could any at all.  So don’t know about them being a player out there.  if it can only just barely get the capsule out there, it won't be much good as a cargo carrier.

So, if NASA is interested in any commercial cargo service to an EML2 station, SpaceX would probably be about the only player there.  And they could probably do it pretty cheap compared to NASA using SLS.  ULA could offer service for propellant deliveries if the EML2 gateway was a depot too.   However, NASA may just launch a large MPLM along with Orion to EML2 and have that be the cargo carrier during a crew rotation if indeed the EML2 gateway will be staffed at times other than an active mission.  A reason to get the SLS flight rate up a little more, and not mess around with commercial cargo.

[go4mars]

curious as to what people think are the possibles,
and what are the desirables. 

I think these are all possible, but I'll rank them in order of desireability from my perspective (which aims for maximum return for tax dollars in current environment).

Note that I changed this first one:

Pure prize option (NASA pays only whoever accomplishes a specified goal first by any means).  If no credible effort from the private sector, then up the prize purse incrementally.

Non-NASA operator (NASA specifies requirements, non-NASA companies supply solutions however they want to (NASA doesn't design the solutions))

Mixed Structure (some traditional NASA, some commercial pieces)

COTS/CRS style resupply

Traditional NASA structure, with Traditional NASA resuppply

[Celebrimbor]

I just don't think that manned space will pass any rational cost benefit analysis within commerical companies in the next few decades. Commercial will only put humans in space if they are explicitly paid to do so...

Therefore their role in EG would not be in utilization, it would be in resupply & crew transfer contracts.

I can see commerical space getting much more involved with a purely robotic fuel depot than EG.

[cosmicvoid]

Maybe I'm missing something here, but I don't understand why all the references are to EML2.  ISTM that EML1 would be a preferable location.  Is there some reason why not?

What are the pros and cons of the two choices?

[rklaehn]

Maybe I'm missing something here, but I don't understand why all the references are to EML2.  ISTM that EML1 would be a preferable location.  Is there some reason why not?

What are the pros and cons of the two choices?

EML2 is easier to get to from a delta-v point of view: 3.43 km/s vs. 3.77km/s. The practical difference is even bigger since entering EML1 requires a relatively large maneuver many days after launch, that has to be done by the spacecraft using storable propellants. The upper stage can't do it because of boiloff.

For entering EML2 on the other hand most of the delta-v can be provided by the much more efficient upper stage just hours after launch, so boiloff is not a problem.

And it is further out in the earth gravity well, so it is closer to earth C3=0, which is advantageous for missions beyond earth (asteroid or mars). That is why it was baselined by the ULA exploration papers from 2009.

By the way: communication to EML2 is not a problem. You can put the station in a halo orbit around EML2 that has a direct line of sight to earth.

The downside is that the transit time to EML2 is higher, which requires more consumables for a crewed flight. But for an exploration gateway that is manned for months, or as a staging area for missions that last years, it does not really make a difference.

[cosmicvoid]

(snip)
By the way: communication to EML2 is not a problem. You can put the station in a halo orbit around EML2 that has a direct line of sight to earth.
(snip)

Ok, thanks, I get it now.  The orbit around EML2 for direct sight of earth answers my thought about comm problems.

[A_M_Swallow]

By the way: communication to EML2 is not a problem. You can put the station in a halo orbit around EML2 that has a direct line of sight to earth.

Although you do have to add delta-V to enter the HALO orbit and rendezvous with the spacestation.

[Jason1701]

Maybe I'm missing something here, but I don't understand why all the references are to EML2.  ISTM that EML1 would be a preferable location.  Is there some reason why not?

What are the pros and cons of the two choices?

EML2 is easier to get to from a delta-v point of view: 3.43 km/s vs. 3.77km/s. The practical difference is even bigger since entering EML1 requires a relatively large maneuver many days after launch, that has to be done by the spacecraft using storable propellants. The upper stage can't do it because of boiloff.

For entering EML2 on the other hand most of the delta-v can be provided by the much more efficient upper stage just hours after launch, so boiloff is not a problem.

And it is further out in the earth gravity well, so it is closer to earth C3=0, which is advantageous for missions beyond earth (asteroid or mars). That is why it was baselined by the ULA exploration papers from 2009.

By the way: communication to EML2 is not a problem. You can put the station in a halo orbit around EML2 that has a direct line of sight to earth.

The downside is that the transit time to EML2 is higher, which requires more consumables for a crewed flight. But for an exploration gateway that is manned for months, or as a staging area for missions that last years, it does not really make a difference.

Very interesting. Do you know the delta-vs to L1 and L2 from the lunar surface? That would be good to know for any manned lunar landings from the Gateway.

[Ben the Space Brit]

For me, cargo and propellent delivery to any putative gateway station is the #1 way they can contribute (although pre-placement of equipment at landing sites is a mid-term possibility).  What makes this valuable is that it would impell the development of BEO-capable commercial launch vehicles and the consequential reduction of costs to launch to EML-1.  This can only make it easier to explore and, ultimately, exploit, whatever viable resources the Moon may hold.

[luksol]

I think that when talking about private sector involvement the first question that has to be asked is why would they want to go there?

There has to be a reason for commercial companies to go there. I understand the resupply missions can be profitable, but only as long as NASA (or someone else) pays for it. Any further involvement depends on any other possibilities available at EML2, commercial, not scientific possibilities.

If such possibilities are to be found, then the commercial sector can participate in EML2 station construction, ops etc using their own resources rather than just being paid for by NASA.

In my opinion this is the first question that has to be answered.

[Ben the Space Brit]

I think that when talking about private sector involvement the first question that has to be asked is why would they want to go there?

It's a bit of a 'chicken or egg' question.  After all, until the commercial access capabilities are available, it won't be possible to go there.  So, as with ISS, NASA will have to be the "anchor tenant".  However, once the capability is there and more affordable, then the possibility emerges of operations like Planetary Resources following for their own reasons.  Until that capability is there, then reasons won't appear (at least not with profitable ROIs).

I suppose it is possible that some enterprising billionaire will take a risk but it isn't likely unless there is a major game-changing discovery or technological development.

[rklaehn]

Very interesting. Do you know the delta-vs to L1 and L2 from the lunar surface? That would be good to know for any manned lunar landings from the Gateway.

I think everything you need to know about getting from EML2 to the lunar surface should be in here:
http://www.ulalaunch.com/site/docs/publications/AffordableExplorationArchitecture2009.pdf

Edit: This should also be a reminder that commercial is not just spacex. If ULA was freed from the artificial restrictions by its parent companies, they could be very competitive with spacex.

They give a delta-v from the lunar surface to the EML2 gateway of 2650m/s (including gravity losses). It should be roughly the same going from EML2 to the lunar surface. But this of course depends a bit on where you want to land on the moon.

[rklaehn]

By the way: communication to EML2 is not a problem. You can put the station in a halo orbit around EML2 that has a direct line of sight to earth.

Although you do have to add delta-V to enter the HALO orbit and rendezvous with the spacestation.

Do you? When you pass EML2 you need to do a burn to cancel your velocity so you stay at EML2. Going directly to the halo orbit would just mean tweaking this burn a bit. I don't think you need additional delta-v. You might even save some delta-v.

In any case the halo "orbit" is not really an orbit but just a very slow (~28 day period) movement around EML2. You have the same semi-major axis and thus the same orbital period of EML2, but higher excentricity and a slightly inclined orbital plane relative to the orbital plane of the moon.

[MikeAtkinson]

Potentially it is a good idea to use CRS and commercial crew spacecraft for gateway support.

But: commercial crew vehicles do not have sufficient delta-v, and would need an upgrade of all their systems. CRS vehicles probably have too little payload capacity (even with a FH launch) and Dragon does not have the delta-v to return cargo to earth.

[Edit: I would love to be proved wrong here!]

The main reason it is potentially a good idea is that it might be cheaper as there would be synergies with ISS support.

Assuming a delta-v from LEO to EML2 of 3.43 km/s, a falcon heavy should be able to get a dragon with a weight of 10t to EML2. The GTO payload of falcon heavy is supposed to be 19t, and EML2 is less than 1km/s from GTO.

On the way back you would have to rely on the dragon propulsion system to get the dragon on an intercept with the earth atmosphere. But getting from EML2 back to a highly elliptical orbit that intercepts the earth atmosphere just requires ~1km/s if you do it in one burn, and even less if you do a powered moon flyby.

So getting back from EML2 to earth is well within the capability of the dragon.

Arguably, flying a dragon to EML2 and back would be a good way to spend the initial falcon heavy launch. They will have many used dragons by the time falcon heavy lauches. It would prove multiple things like deep space operations and return from almost hyberbolic velocity. And it would be a first.

edit:

getting the dragon to and from EML2 would probably be easiest doing a three impulse transfer: an initial burn from LEO to the lunar vicinity of 3.142km/s, which would be done by the falcon heavy upper stage, a burn close to the moon of 0.184km/s, and a burn to enter EML2 of 0.148km/s. The latter two would have to be done by the dragon. On the way back you do everything in reverse.

So the total delta-v from LEO is 3.142km/s for the falcon heavy upper stage, and 0.664km/s for the dragon.

To get a station to EML2 you would probably use a weak stability boundary trajectory. That takes about 3.1km/s in a single burn at the beginning of the mission So you should be able to launch a pretty reasonable space station module (~16t) directly to EML2 using a falcon heavy.

Now that SpaceX have put a figure of 12,000 kg on FH GTO performance it looks like my suspicions were correct.

[simonbp]

Just a note on trajectories: the propulsive lunar gravity-assist trajectory (two impulse after TLI) is a good combination of transfer time and delta-v. It is not, however, a free-return trajectory. The single-impulse lunar gravity-assist can be free-return, and so may be preferable for crew missions to L2. Two-impulse would still be the best option for return to Earth, though.

For getting the station to L2, a standard low-thrust spiral is more likely. It's by far the most optimized for a solar-electric transfer stage, and naturally cancels out any phasing and inclination effects from assembling the station at ISS. Even for a WSB trajectory, the mass of propellant required to send a proper station to L2 is probably large enough to justify the SEP stage (especially considering that they are apparently scaling the gateway to SLS).

WSB-type trajectories may be useful for cargo runs, though, and would need to be traded with the extra cost of a SEP stage. I would be curious what a Cygnus with extra solar arrays and an ion engine could haul to L2...

[pathfinder_01]

Now that SpaceX have put a figure of 12,000 kg on FH GTO performance it looks like my suspicions were correct.

For resupply FH and Delta heavy are enough.

When it comes to life support you are often volume limited. Not mass limied.

According to this: http://futureinspaceoperations.com/papers/HumanOps_Beyond_LEO_11_2010.pdf

A single dragon capsule with 10 meters cubed presurized volume would hold enough for a crew of 3-4 for about at most 180 days but likely more likely 60 due to volume.

A Cygnus with 18.9 meters volume 90 days. Dragon only masses 4mt dry so there is room to add a more massive service module.Cygnus is only 1.5Mt, so again room to add a serivce module(or more fuel tanks).

Moving the station is what will require SEP or multiple launches.