totm dec 2023 Artemis Discussion Thread

[Ultimate Steve]

3 minutes ago, jinnantonix said:

On 2/7/2020 at 4:03 PM, Ultimate Steve said:

 

The SLS is designed to launch Orion, and it is by far the closest to achieving human rating.  The fact is, Orion is a big craft, with room for 6 astronauts, much bigger and heavier than the Apollo return capsules.  The intent is to have a craft more versatile for multiple BLEO operations (cislunar, heliocentric and Mars), and ability to return directly from heliocentric orbit to the Earths surface (ie survive >3km/s re-entry speeds).  The downside of this is that it is just too big to get to LLO and return to Earth in a single launch with current rockets.  A bigger human rated rocket is a decade away at least.

I don't understand the obsession with getting Orion to LLO.   Why is it necessary?  Why not make it standard practice for Orion to enter a highly elliptical orbit, and lunar operations must then be capable of getting to and from the lunar surface from that point?  I simply do not see the downside of that, and creating complex a difficult scenarios to achieve Orion LLO are only going to add cost and time.  

A better question: "Is the Gateway needed?".  I would argue, no.  There is no reason why each mission could be completed with an ad hoc LOR in highly elliptical orbit.  But having a staging point for cargo delivery and a permanent position for advanced comms has some advantages.

Here is my RSS simulation of Artemis 3 which assumes LOP-G is in place, and completes a manned lunar landing with two launches (SLS + FHe).  I think this is basically what NASA is aiming at.  My 3-stage lunar lander meets the spec for HLS, but may be too small in physical dimensions to support 2 astronauts on the surface for 2 weeks.  The current HLS proposals seem to be too large and heavy to complete the mission from a single FHe launch.  The options are single SLS Cargo launch (bad idea, way too expensive) or better two commercial Falcon Heavy launches with EOR. 

The idea behind getting Orion to LLO is to reduce the work the lander has to do, as in many scenarios removing work from the lander at the expense of adding work to Orion and/or a transfer stage is worth it.

 

NOTE: I spent waaaay too much time crunching these numbers to make sure, and a lot of them use approximations based on the baseline 24 ton lander mentioned earlier, intended more to show relative increase in mass using a baseline number than actual masses, as masses will vary depending on the mission architecture. I can guarantee you I didn't calculate every scenario and some of what follows is probably wrong.

TL;DR: Going to LLO with the SLS-Constellation architecture reduces the total mass needed to TLI by about 5 tons compared to the Gateway architecture, assuming a 26 ton Orion CSM, a 24 ton lander (capable of going to and from LLO) and a 1 ton dry mass stage with X tons of propellant, either directly attached to the lander to increase Delta-V or for braking the whole stack into LLO. Highly Elliptical Lunar Orbit and Lowly Elliptical Lunar Orbits, both using distributed launch (Gateway without Gateway) were also briefly touched on, with HELO performing about the same as SLS-Constellation LLO using an elliptical orbit with the same Delta-V requirements to LLO as Gateway (note, higher elliptical lunar orbits may be possible according to a diagram I found but they get worse the higher you go) and LELO (as low as Orion could go and still make it back) outperformed all the other options, requiring 11 tons less fuel compared to the Gateway architecture. However the gains from both elliptical orbit distributed launch architectures would be at least partially offset by the Delta-V needed for stationkeeping, as these landers would likely be waiting for Orion for a while and very few lunar orbits are stable. Gateway's orbit was chosen for low stationkeeping cost, and SLS-Con gets around this by not waiting for Orion, with the only loiter in orbit done while the surface mission takes place. If using commercial launch vehicles, both ELO rendezvous methods would likely require a multi piece lander, something SLS-Con avoids.

 

Additional note: For Gateway and ELO (specifically HELO) missions I only calculated direct ascent landers. A mission where the transfer vehicle takes the ascent stage of the lander back to Gateway may tip the scales significantly, however that requires a lot more calculation and I already did quite a bit.

 

If that is good enough for you you can skip down to the bold STOP! where I address your other points.

 

The lander already has to do roughly 4km/s, more if you want margin, for the landing and ascent, going to and from elliptical lunar orbit adds I believe over 1km/s total which is a substantial increase in mass due to the rocket equation. Granted, bringing the rather heavy Orion to LLO also brings in a significant fuel cost, but I would tend to believe that being able to fit more science/crew/equipment/life support on the lander would outweigh the negatives.

As the Orion CSM already has the fuel to leave LLO and get home, the full stack would need ~850m/s to break into LLO from TLI assuming an Apollo speed transfer. According to this:

It is roughly 420m/s each way from TLI to NRO. Not sure if that is different from NRHO but I can't find any other numbers so I'll use the NRO numbers. According to this:

It is ~730m/s from NRO to LLO.

The 420m/s from TLI to NRO plus the 730m/s from NRO to LLO ends up being 1150m/s, which is 300m/s more than just going directly from TLI to LLO due to the inefficient maneuvers required to reach NRO. Granted that gap will grow slightly smaller when factoring in that we need a polar LLO for many of the Artemis objectives, but most of the work to be on the right trajectory is done in the TLI burn if my information is correct.

Granted, if we go with what you said, ditching gateway and doing an elliptical lunar orbit, there is no gap.

 

Warning: Potentially inaccurate napkin math ahead

 

In a gateway style architecture, in addition to the landing itself, the lander would have to do an extra 730m/s both down and up, ~1.5km/s of additional Delta-V over an Apollo style mission. This is in addition to the 420m/s that the lander or lander delivery system needs to have to get from TLI to the gateway in the first place. This cuts into the payload of the launch vehicle. In effect, this means the lander/delivery system needs 1.9km/s more than a standard 4km/s (plus margin), although delivering the lander in multiple pieces may mess with the additional 420m/s. In this scenario, Orion uses just ~840 of its 1300m/s Delta-V budget, plus corrections.

 

In the SLS-Constellation style architecture, the lander needs an Apollo-esque amount of Delta-V (4km/s plus margin) and the Orion needs to use roughly 1km/s of its delta-V stores to both rendezvous in LEO and complete the TEI (return to Earth) burn. The addition, however, is the stage needed to brake into LLO, which needs ~850m/s (although in my first calculation this was just 800m/s with the Orion CSM doing the rest). It will be difficult to do the math without knowing whether a 2 or 3 stage lander is used and the masses of each components, but if we take my lander mass numbers from my original post (not the best comparison, certainly not a particularly fair one, but an easy one), which is 24 tons, the full stack would be 50 tons, and 15 tons of excess propellant and a 1 ton dry mass stage would be needed to brake into LLO. If we assume the same lander mass but add 1.5km/s to it as in the gateway style architecture, assuming a 1 ton dry mass stage you would also need 15 tons of propellant, exactly the same amount of extra mass, until we factor in the extra 420m/s required to reach gateway in the first place, in which case the needed fuel mass jumps up to 21 tons. Note: These numbers all assume 320s isp.

Note: This assumes just taking 24 tons and adding Delta-V to it, which doesn't accurately account for staging but also gives a generous mass ratio for the transfer stage. It should be accurate enough for napkin math.

The mass numbers are kind of arbirtrary, but the point is to illustrate that in a Gateway architecture, especially where the lander is delivered by commercial launch vehicles which have fairly limited TLI mass capability, more of the lander mass budget would have to go towards the extra Delta-V requirements Gateway poses rather than towards useful payload to the lunar surface. Alternatively more assembly missions could be done to assemble the lander, but this does add cost and complexity, although by some arguments not much.

As far as using an Elliptical orbit instead of NRO as you alluded to above, this is where things could get interesting. I'm going to briefly touch on highly ELOs like you said and lowly ELOs. In both, however, the 300 extra m/s required to stop over at Gateway is eliminated.

In a highly elliptical lunar orbit, which I'm going to assume roughly equates to NRO in terms of Delta-V from LLO to that orbit, the benchmark lander would need 15t of propellant. The chart above says that the requirements are actually more, but I suspect that's for extremely elliptical orbit rather than just a highly elliptical orbit. This puts it on par with SLS-Con.

As for using a low Elliptical orbit, specifically as low as possible, this can also take a significant amount of Delta-V away from the lander's requirement, although it would still need to be delivered on a separate launch. Assuming Orion is using its full 1300m/s on just LOI and TEI, that is 650m/s each way, leaving Orion in an elliptical orbit just 200m/s from LLO. Starting from there, this makes the lander requirements 4.4km/s plus margin (200m/s from LLO both ways), but including the 650m/s needed to reach that orbit from TLI, the lander and delivery system needs 5.05km/s of Delta-V, 1.05km/s above the standard 4km/s. Assuming that same 24 ton lander (as a benchmark), this just needs 10 tons of fuel mass (assuming 1t dry transfer stage) which is lower than the 15 and 21 ton numbers of the above approaches. However, due to the limitations of commercial LVs this would still have to be assembled in multiple pieces in order to have decent capabilities.

There are a lot of ways the elliptical orbit method can be tweaked as there are many different elliptical orbits. I will not attempt to model any more.

Note: Elliptical lunar orbits tend to be more unstable than both LLO and NRO and need noticeable amounts of Delta-V for stationkeeping.

The above data suggests that a lowly ELO is better than a highly ELO when using distributed launch, at least up to the point of using most of Orion's fuel, as it reduces the Delta-V requirements for the lander. Even with a separate lander launch you would want your starting orbit to be as low as possible (at a point where Orion could still leave, of course) as the lander/delivery system would only have to go down to that elliptical orbit once, but from there would have to go both down to and up from the moon.

 

From a mass/Delta-V standpoint Lowly ELO is actually looking to be the superior option here, beating out SLS-Con by 5 tons and Gateway by 11 tons (using the benchmark lander). However as pointed out above, SLS-Con has the advantages of not needing assembly in lunar orbit. SLS-Con would also use less in stationkeeping than Lowly ELO as LELO is more unstable, and the lander would likely be parked there for months before Orion could arrive. LELO does also have the advantage of not needing SLS Block 2, however, a very important advantage as the biggest prerequisite for my plan was skipping straight to Block 2.

 

Summary to your first point "Why bother with LLO:" It reduces lander Delta-V requirements by a substantial amount over a Gateway based architecture, allowing for more lander mass to be dedicated to surface payload. However, it was discovered that for some architectures Lowly Elliptical Lunar Orbit is advantageous over Highly Elliptical Lunar Orbit, NRO, and LLO.

 

 

 

Stop!

 

 

Okay, now for the other points.

Addressing Gateway you make good points as to why it is not needed but may be good to have. I would additionally like to add that with a lunar station of some kind launched (not necessarily in NRO), it becomes more politically feasible to continue any lunar program as many politicians wouldn't want to abandon that infrastructure. It also adds more options for international cooperation, further helping the likelihood of the program to continue.

As you correctly assert, SLS is the only rocket that has been designed to launch Orion and is the only one theoretically capable of launching Orion that is planned to be man-rated. However, Orion has already been launched once on a rocket that it wasn't specifically designed for, although admittedly it wasn't crew rated. The same thing could be done with Falcon Heavy, except Falcon Heavy would likely be much easier to man rate than Delta IV Heavy, as its component cores are extremely similar to F9 cores that are crew rated, and at one point man crew rating FH was on the table. While it isn't exactly ideal, it is within the realm of possibility. Considering the cost of the overall mission including a Block 2 SLS, this is very minor, but the Falcon Heavy could be partially reusable in this scenario. I'm not sure if the margin is great enough for side booster RTLS but it is almost certainly enough for double ASDS landing (center core expended in both cases).

Your video is interesting and provides a good look into how something like this could work. I must ask you, however, what is the mass of that lander (minus the transfer stage), as a 2 man lander much lighter than the 16 ton Apollo LEM may prove difficult, and is NRO modeled properly with the Delta-V requirements that tend to be above that of ELO (chart above) (possibly only for LOI, and not for descent/ascent)? The additional delta-v can make or break missions like these.

[mikegarrison]

This whole thing is a nightmare optimization problem. Everybody has different goals and constraints. Some people want a Gateway Station as a priority, and leads to one optimum. Others want to maximize payload landed and recovered from the Moon for each mission, and that leads to a different solution. Some want polar landing sites. Some want a fully reusable lander. Some want everything designed around the SLS. Others don't want the SLS used at all. Some say we have to use Orion as it is, while others say it's easier to redesign Orion than to design everything else around Orion's limitations.

Apollo had problems, but not like this. They could at least agree that the goal was to land people on the moon, grab some rocks and leave some instruments, then get them home. No permanent bases, no reused resources, each mission self-contained in a single Earth launch. And none of the hardware was designed to be used for any other mission (even though it later eventually was repurposed for Skylab).

[tater]

11 hours ago, jinnantonix said:

The SLS is designed to launch Orion, and it is by far the closest to achieving human rating.  The fact is, Orion is a big craft, with room for 6 astronauts, much bigger and heavier than the Apollo return capsules.  The intent is to have a craft more versatile for multiple BLEO operations (cislunar, heliocentric and Mars), and ability to return directly from heliocentric orbit to the Earths surface (ie survive >3km/s re-entry speeds).  The downside of this is that it is just too big to get to LLO and return to Earth in a single launch with current rockets.  A bigger human rated rocket is a decade away at least.

SLS might have been designed to carry Orion, but not for any particular, useful mission.

Orion is not versatile. The missions it might be involved with all require other vehicles. A lander, which SLS cannot comanifest, a Mars craft (which has to be constructed in space), etc.

 

11 hours ago, jinnantonix said:

I don't understand the obsession with getting Orion to LLO.   Why is it necessary?  Why not make it standard practice for Orion to enter a highly elliptical orbit, and lunar operations must then be capable of getting to and from the lunar surface from that point?  I simply do not see the downside of that, and creating complex a difficult scenarios to achieve Orion LLO are only going to add cost and time.  
 

Because the lander has to go to LLO regardless. If ascent takes you to LLO, then you phase and head to nrho/Gateway/whatever, that’s an added burn, and possible failure mode. It also constrains when you can go and leave. If there’s an emergency, you can’t just leave, you have to wait a week for Orion to swing by again.

[jinnantonix]

16 hours ago, Ultimate Steve said:

Excellent graphic, with a lot of really interesting information.  I tried to follow your "napkin maths", but with difficulty.  The basic points I get are:

• LLO is ideal for optimising the lander for delivery of payload to lunar surface.  Basically you can get a better lander and more payload to surface per mission.
• NRHO or Lagrange Point is ideal if building a space station, and LLO or ELO is not ideal. Lowly ELO is better than highly ELO is better than LLO.
• For delta-v, lowly ELO is better than NRO, Lagrange, and highly ELO.

Quote

Addressing Gateway you make good points as to why it is not needed but may be good to have. I would additionally like to add that with a lunar station of some kind launched (not necessarily in NRO), it becomes more politically feasible to continue any lunar program as many politicians wouldn't want to abandon that infrastructure. It also adds more options for international cooperation, further helping the likelihood of the program to continue.

Good point in favour of the Gateway.  From your points above, it does make sense that if there is a space-station, NRHO or Lagrange is the best location for station-keeping.

So, two options emerge

• if Gateway happens, then the Artemis plan for NRHO is OK as it provides best station-keeping, though places stress on the lander design **, and reduces payload to surface.
• if no Gateway ++ then:

1. Modify Orion to allow it to go to lowly ELO, as this gives best compromise between station-keeping and payload to surface
2. Scrap Orion and start again with an Apollo style capsule, and potentially single launch to lowly ELO.

Notes: 
** if the current tender for HLS fails to come up with an adequate facility for humans and payload delivery, it may yet spell doom for the Artemis architecture, and Gateway.
++There is probably no option for lander re-usability in the "no Gateway" option.
 

Quote

As you correctly assert, SLS is the only rocket that has been designed to launch Orion and is the only one theoretically capable of launching Orion that is planned to be man-rated. 

There is no question that FH could be man-rated, the same for New Glenn, but it would result in a delay of at least a decade.  And if we were going to do that, then we would likely scrap Orion in it's current form and rebuild that with a LLO capability, and also scrap SLS altogether in favour of FH and NG.  So $Billions in development costs wasted, and throw a lot of people out of work, probably lose a lot of skills and experience.  What staff remain will likely be tax-payer funded to achieve the man-rating on the commercial carrier.  This would kill the current inertia toward a moon landing this decade, with no certainty it would start up again.  Not sure why anyone would want that.

My vision (and I am sure I am not alone) is that FH and NG will eventually be man-rated and will be the primary carriers of humans and equipment to space by 2030 and beyond.  The R&D for this can and will be carried by the commercial carriers, not the taxpayer.  If we want anything to happen this decade, we need SLS and Orion.  The only question is whether we go ahead with Artemis and Gateway, or redesign for Apollo style single non-re-usable missions.

 

 

Edited February 9, 2020 by jinnantonix

[tater]

New Glenn is man rated. From go. Blue has said this since forever—they will build no rockets that cannot carry people.

[Ultimate Steve]

1 hour ago, jinnantonix said:

Excellent graphic, with a lot of really interesting information.  I tried to follow your "napkin maths", but with difficulty.  The basic points I get are:

• LLO is ideal for optimising the lander for delivery of payload to lunar surface.  Basically you can get a better lander and more payload to surface per mission.
• NRHO or Lagrange Point is ideal if building a space station, and LLO or ELO is not ideal. Lowly ELO is better than highly ELO is better than LLO.
• For delta-v, lowly ELO is better than NRO, Lagrange, and highly ELO.

Yes, those were pretty much the takeaways with some variance to the ideal based on what the mission goals are.

1 hour ago, jinnantonix said:

So, two options emerge

• if Gateway happens, then the Artemis plan for NRHO is OK as it provides best station-keeping, though places stress on the lander design **, and reduces payload to surface.
• if no Gateway ++ then:

1. Modify Orion to allow it to go to lowly ELO, as this gives best compromise between station-keeping and payload to surface
2. Scrap Orion and start again with an Apollo style capsule, and potentially single launch to lowly ELO.

Option bullet point: True, although the stresses on the lander design can be very severe.

Option 1: Yes, although I would like to say that Orion probably doesn't need much modification for this, the lowly ELO calculations were done with Orion's current Delta-V, although thermal stress might change. IDK how bad the stationkeeping would be in this orbit, but another option could be to build the Gateway here, avoiding the Delta-V penalty taken to stopover in NRHO, while retaining most of the advantages of Gateway. Will probably need a relay though.

Option 2: As you point out below this would kill momentum and is not really a good idea. A better option if getting to LLO is important may be extending just the service module (quite a bit of work but not as much as scrapping Orion and starting fresh, and this option is being proposed IRL I believe), or carrying a small dockable tug module with the fuel to push Orion to LLO as co-manifested cargo on the SLS launch. Not sure if Block 1 can handle this but B1B will almost certainly be able to. There are several existing tugs to choose from, although they would have to be modified for the job (mostly certification, BLEO power and comms (not much of an issue for tugs designed to operate at geostationary altitudes), and adding a docking port), and many of them are Russian, which isn't unfortunate from an engineering perspective but is unfortunate from a political perspective. It would be much less work compared to scrapping Orion but it may not be worth it compared to LELO operations as the hit on the lander is comparatively minor from LELO compared to NRHO.

A bonus of going all the way to LLO, specifically the 86 degree inclination frozen lunar orbit would require far lower station-keeping Delta-V than HELO or LELO although more than NRHO, which would be good if we decided to put Gateway in LLO. It would mean more work to get Gateway modules there, but less work for the lander. It would also allow for lander reusability which was one of the main problems with HELO LELO and LLO proposals without a Gateway. Due to lower Delta-V requirements, it would also be easier to do a single stage lander from here than from any other orbit, which, in the far future could be refueled from the surface. This option is, however, not ideal if Gateway is supposed to be an assembly point for Mars vehicles in addition to a place to stage lunar landings. It would be lander optimized but not Mars optimized, although in many respects NRHO is definitely far from Mars optimized too.

 

52 minutes ago, jinnantonix said:

++There is probably no option for lander re-usability in the "no Gateway" option.

True, this is a major disadvantage.

55 minutes ago, jinnantonix said:

Quote

 

There is no question that FH could be man-rated, the same for New Glenn, but it would result in a delay of at least a decade.  And if we were going to do that, then we would likely scrap Orion in it's current form and rebuild that with a LLO capability, and also scrap SLS altogether in favour of FH and NG.  So $Billions in development costs wasted, and throw a lot of people out of work, probably lose a lot of skills and experience.  What staff remain will likely be tax-payer funded to achieve the man-rating on the commercial carrier.  This would kill the current inertia toward a moon landing this decade, with no certainty it would start up again.  Not sure why anyone would want that.

If it did take a decade and we decided to redesign Orion, bad things would happen, but I highly doubt it would take a decade or more to man rate FH or NG. If my memory serves me correct, NG is designed to be man rated from the beginning (and BO is probably working on an orbital capsule for NG behind the scenes but we can't be sure) and FH was at least originally intended to carry humans although late into development they decided to drop that capability, mainly because of optimism surrounding Starship, but Musk has said that it is still on the table if needed.

Quote

Musk, in the call with reporters, did not rule out flying people on Falcon Heavy, but only if there were delays in the development of BFR. “We’ll see how the BFR development goes,” he said. “If that ends up taking longer than expected, then we will return to the idea of sending a Crew Dragon on a Falcon Heavy around the moon, and potentially do other things with crew on Falcon Heavy.”

https://spacenews.com/spacex-no-longer-planning-crewed-missions-on-falcon-heavy/

If tomorrow they were told they needed to man rate FH I can just about guarantee, unless something very catastrophic happens to SpaceX or the country/world, that it will not take them 10 years.

1 hour ago, jinnantonix said:

My vision (and I am sure I am not alone) is that FH and NG will eventually be man-rated and will be the primary carriers of humans and equipment to space by 2030 and beyond.  The R&D for this can and will be carried by the commercial carriers, not the taxpayer.  If we want anything to happen this decade, we need SLS and Orion.  The only question is whether we go ahead with Artemis and Gateway, or redesign for Apollo style single non-re-usable missions.

In a world with no major vehicle developments in the next decade, this could very well be the case (although as said above I think the man rating would happen in far less than 10 years), and SLS is currently the optimal vehicle to launch Orion.

However, I don't see this decade passing without major launch vehicle advances. Who knows what China is doing, but they have ambitious plans, only partially public, and aim to fly their cross between Orion and Dragon for the first time in the next few months if I remember correctly (although this wouldn't directly help with American efforts besides maybe a political push to remain first in space. Space Race II anyone?). New Armstrong is a complete wild card but could possibly happen. Starship is another huge wild card (although arguably further along than NG in several ways at this point), but even if it completely fails I don't expect SpaceX to sit still for another decade considering all they managed to achieve in the last decade. Just for example, a Raptor based expendable heavy or super heavy launch vehicle even under 9m would be formidable, Musk has mused on the possibility of Falcon Super Heavy (5 cores) in the past, and if they can't figure out upper stage reuse, a Starship but with an expendable upper stage (but a reusable lower stage) would also be fairly formidable. Man rating these concepts is also another huge wild card, especially Starship as currently planned due to it lacking an escape system. In the case where Orion and possibly an upgraded Dragon 2 are the only US BLEO capable vehicles, there are still options to get them BLEO besides the wild-card non man rated SHLVs and SLS. Launching the capsule to LEO on a man rated rocket and then rendezvousing with a transfer tug launched by a non man rated rocket could open up possibilities. This could be something Raptor based or possibly ACES.

 

[jinnantonix]

11 hours ago, Ultimate Steve said:

Option bullet point: True, although the stresses on the lander design can be very severe.

I am sure the teams putting together the HLS bids are well aware of that. 

My video above simulates a 3-stage craft with a 2.7t ascent vehicle and 1 ton surface payload delivery (including humans and life support).  The ascent vehicle is reusable provided it can be refueled at the Gateway.  Perhaps this is adequate to achieve the Artemis mission goals?

[tater]

2 hours ago, jinnantonix said:

I am sure the teams putting together the HLS bids are well aware of that. 

My video above simulates a 3-stage craft with a 2.7t ascent vehicle and 1 ton surface payload delivery (including humans and life support).  The ascent vehicle is reusable provided it can be refueled at the Gateway.  Perhaps this is adequate to achieve the Artemis mission goals?

That Ascent vehicle is what, 1 tonne less than the Apollo LM (4700kg loaded vs 2700+1000cargo)?

Any Artemis surface stay is at minimum one Gateway orbit (6.5 days?), and issues and the crew needs to survive for 13 days, so I assume that's the min spec for surface stay, since they don't have abort options with highly elliptical orbits. I guess as long as they land supplies ahead of time (a hab?) it's not a problem, though.

Abort modes seems like the largest issue to me. We have a NASA deeply concerned about capsule aborts during all parts of ascent, free return trajectories, etc, then they will fully commit to a lunar landing with really marginal abort options? The Ascent vehicle can have the dv to get from the surface all the way to Gateway, but unless it does that with large margins, it's not really an abort to Gateway, it's an abort to some LLO that they can phase over days, and do the rendezvous burn to Gateway (or just Orion) in X days when Gateway is in the right position. Margin in this case being maybe props, certainly life support, etc.

16 hours ago, jinnantonix said:

There is no question that FH could be man-rated, the same for New Glenn, but it would result in a delay of at least a decade.  And if we were going to do that, then we would likely scrap Orion in it's current form and rebuild that with a LLO capability, and also scrap SLS altogether in favour of FH and NG.  So $Billions in development costs wasted, and throw a lot of people out of work, probably lose a lot of skills and experience.  What staff remain will likely be tax-payer funded to achieve the man-rating on the commercial carrier.  This would kill the current inertia toward a moon landing this decade, with no certainty it would start up again.  Not sure why anyone would want that.

I'm going to reiterate that Blue Origin has said (always) that New Glenn (notice the astronaut name) is man-rated from the start. They are doing the man-rating work like SLS, ahead of time. If NG flies next year, there is a heavy lift, man-rated boosted next year. Not a 10 year delay, next year.

Quote

Meet New Glenn

Named after pioneering astronaut John Glenn, New Glenn is a single configuration heavy-lift launch vehicle capable of carrying people and payloads routinely to Earth orbit and beyond. Featuring a reusable first stage built for 25 missions, New Glenn will build a road to space.

 

[sh1pman]

2 hours ago, tater said:

I'm going to reiterate that Blue Origin has said (always) that New Glenn (notice the astronaut name) is man-rated from the start. They are doing the man-rating work like SLS, ahead of time. If NG flies next year, there is a heavy lift, man-rated boosted next year. Not a 10 year delay, next year.

Hmm, if a rocket can get man-rated from the start, then why did NASA make SpaceX launch F9 Block 5 seven times (think it was seven or so) without any modifications? Or does Blue need to do the same with NG?

[RCgothic]

Because for spacex it was cheaper and faster to physically demonstrate their cheap and rapidly reusable booster than to perform exhaustive analysis.

Both approaches are valid.

Edited February 10, 2020 by RCgothic

[wumpus]

1 minute ago, sh1pman said:

Hmm, if a rocket can get man-rated from the start, then why did NASA make SpaceX launch F9 Block 5 seven times (think it was seven or so) without any modifications? Or does Blue need to do the same with NG?

Presumably you can trade launch success for paperwork (see ULA vs. SpaceX tests for abort testing).  F9 was never built around crew rating, so needed much more proof of safety.

Now explain just how much testing SLS needs before strapping astronauts to a Boeing safety-certified rocket.  Personally by now I'd be throwing away any paperwork from Boeing (and thus ULA as well) and demanding full safety tests.  But the Senate (and apparently the House) would never stand for such foolishness.

[tater]

8 minutes ago, sh1pman said:

Hmm, if a rocket can get man-rated from the start, then why did NASA make SpaceX launch F9 Block 5 seven times (think it was seven or so) without any modifications? Or does Blue need to do the same with NG?

Same as Starliner vs Dragon. You can certify every part and subsystem as you go, or you can build the thing, then test it. SpaceX does some of each, more of the latter than most. Other contractors do mostly the certification, less on the all-up testing.

Some of the SLS/Orion cert was because there was all-up testing—on the Space Shuttle. Orion SM engines are Shuttle OMS engines. SLS is SSMEs, etc.

SRBS were certified on Shuttle, as well.

Regardless, NG is a crew certified boosted from the get go.

Edited February 10, 2020 by tater

[Ultimate Steve]

Just now, wumpus said:

Presumably you can trade launch success for paperwork (see ULA vs. SpaceX tests for abort testing).  F9 was never built around crew rating, so needed much more proof of safety.

Now explain just how much testing SLS needs before strapping astronauts to a Boeing safety-certified rocket.  Personally by now I'd be throwing away any paperwork from Boeing (and thus ULA as well) and demanding full safety tests.  But the Senate (and apparently the House) would never stand for such foolishness.

Yeah. My greatest fear for the Artemis/SLS/Orion program is a major failure. If Artemis 1 fails catastrophically, it would mean massive delays if not a cancellation of the program.

[tater]

 

https://www.nasa.gov/news/budget/index.html

Edited February 10, 2020 by tater

[Ultimate Steve]

Summary:

• 25bn overall up ~2.5bn from last year
• 3.4bn for human lander systems
• 700m for lunar surface activities
• Some more for Mars stuff
• Delays Block 1B as it is "not needed to support lunar landings"
• No funding for STEM engagement
• No funding for WFIRST
• A few Earth science missions are cancelled
• Proposes launching Europa Clipper on a commercial launch vehicle instead of SLS, saving 1.5 billion dollars (their words not mine).
• A bunch of other stuff but these are much of the major things

Remember, it still has to pass through the senate, and IIRC the same cuts were proposed last year and they reversed them so they will likely reverse them again, although this may come at the expense of something else.

All in all I think this bill is good, and it is good news for lunar exploration but unfortunately at the expense of Earth science and outreach.

[RCgothic]

So block 2 is over the horizon, and block 1B is now on the chopping block as well.

I guess the difference between "can send Orion Only to TLI" and "can send Orion and not-a-lander to TLI" just isn't big enough.

[tater]

Yeah, B1b is pretty useless. If the dev cost is such that you could buy... who wants to guess what Boeing would charge for EUS? 3 billion? More? 20 FH launches can send a lot of stuff to Gateway for just that money.

[jadebenn]

I expect the proposal to axe Block 1B to go down as well as the last time they tried that in the previous year's budget request. 

Anyone who thinks this is going to be passed still containing language that kills Block 1B is sorely mistaken.

Edited February 11, 2020 by jadebenn

[tater]

5 hours ago, jadebenn said:

I expect the proposal to axe Block 1B to go down as well as the last time they tried that in the previous year's budget request. 

Anyone who thinks this is going to be passed still containing language that kills Block 1B is sorely mistaken.

The (budget) proposal, OTOH, is 100% correct in the assessment that B1B is not needed. B1 can take Orion the only place it can go. B1B cannot do anything useful that B1 cannot already do, since there is not enough comanifested payload to matter or achieve any useful mission goal. Certainly not per unit dollar, since any such cargo can be sent with a choice of CLVs. DIVH, FH, Vulcan Centaur, and NG can all throw anything SLS can comanifest to TLI. As such, any dev cost of EUS is wasted money as long as SLS has Orion on top.

How many B1b comanifested payload massed objects are needed, and how many could you buy/launch just for the dev cost of EUS?

If Boeing needs it for their lander... they should build it on their own dime, IMO.

Edited February 11, 2020 by tater

[RCgothic]

Of course the danger to SLS is that if you can decide "Orion and not-a-lander to TLI" is not meaningfully better than "Orion Only to TLI", then what's to stop "Not-Orion on not-SLS to TLI".

There are a number of commercial options nearing completion. And nothing of value would be lost./s

[sh1pman]

2 hours ago, RCgothic said:

Of course the danger to SLS is that if you can decide "Orion and not-a-lander to TLI" is not meaningfully better than "Orion Only to TLI", then what's to stop "Not-Orion on not-SLS to TLI".

There are a number of commercial options nearing completion. And nothing of value would be lost./s

Not-Orion on not-SLS? So... Crew Dragon on FH? But it doesn’t have the SM to brake and later return to Earth. It’ll need a SM, but then it might get as heavy as Orion. And SLS is the only rocket that can send Orion stack (25t total?) to TLI...

[tater]

5 hours ago, sh1pman said:

Not-Orion on not-SLS? So... Crew Dragon on FH? But it doesn’t have the SM to brake and later return to Earth. It’ll need a SM, but then it might get as heavy as Orion. And SLS is the only rocket that can send Orion stack (25t total?) to TLI...

Yeah, Orion CSM is 26,520kg.

FH can't do it, NG can't do it. In one launch.

Orion CSM plus a "naked" stage 2 with a docking port? FH can, unsure on NG.

All these weird architectures to the Moon are only required because of one of two reasons (or a mixture of both):

1. Orion capsule is far too heavy.

2. SLS is not built to throw enough to TLI.

If Orion was smaller, SLS could send missions to the Moon in 1 go. Gateway could even still be a thing, sent ahead commercial. If SLS was bigger, it could send missions to the Moon as well.

So we know what throw is required to make Artemis work in 1 launch (with Gateway):

~42t for a lander, and Orion is 26.5t. So 62-69 tonnes to TLI is what SLS should have been designed to do. The 3 stage version could use the "transfer vehicle" as a LOI stage and go direct to LLO (Orion can easily get home from LLO, it just can't do both LOI and TEI (particularly with a lander attached). Bottom line is they must have done this math, so they must know down to the kg what the min mass to TLI is given the extant Orion CSM. If they started saying, "Look, we can do the following to SLS and get the throw to TLI to 62 tons, and have a complete lunar capability." I'd say do it, at least the vehicle would bve useful for something.

[sevenperforce]

On 2/9/2020 at 4:40 AM, mikegarrison said:

This whole thing is a nightmare optimization problem. Everybody has different goals and constraints. Some people want a Gateway Station as a priority, and leads to one optimum. Others want to maximize payload landed and recovered from the Moon for each mission, and that leads to a different solution. Some want polar landing sites. Some want a fully reusable lander. Some want everything designed around the SLS. Others don't want the SLS used at all. Some say we have to use Orion as it is, while others say it's easier to redesign Orion than to design everything else around Orion's limitations.

Over and over, I come back to this exact conclusion. There's no good way to optimize, no good solution, because there's no consensus on goals.

[tater]

That's the problem with designing a really, really expensive rocket and spacecraft without any particular goal in mind.

This was the original complaint many of us had about SLS, years ago. Not that it was overly expensive. Not that it had a low launch cadence. Not that it was primarily about pork. Not that it was past due and way over budget—though it is all of those things. Our complaint used to be summed up as "rocket to nowhere."

Too big for LEO, to small for anything else. That remains the primary problem. The other issues like cost—those only matter because if it was much cheaper, if it had a much higher cadence on top of that, then we could work around the fact it's simply not the right size via distributed launch.

 

Edited February 11, 2020 by tater

[sevenperforce]

15 minutes ago, tater said:

That's the problem with designing a really, really expensive rocket and spacecraft without any particular goal in mind.

This was the original complaint many of us had about SLS, years ago. Not that it was overly expensive. Not that it had a low launch cadence. Not that it was primarily about pork. Not that it was past due and way over budget—though it is all of those things. Our complaint used to be summed up as "rocket to nowhere."

Too big for LEO, to small for anything else. That remains the primary problem. The other issues like cost—those only matter because if it was much cheaper, if it had a much higher cadence on top of that, then we could work around the fact it's simply not the right size via distributed launch.

I mean, we can constrain some things. Realistically, SLS is never going to launch anything but a manned Orion to TLI. It will never be useful for distributed launch. It will never reach Block 2, so Block 1B is the only configuration we will actually be able to make use of. So the primary constraint is that we are going to be having Orion and up to 8 tonnes of comanifested cargo coming toward the moon. The cargo will never be able to provide propulsion to Orion, so Orion will have to burn to deliver it to wherever we're going.

Orion is never going to be beefed up (because then SLS can no longer deliver it), so it cannot reach LLO. It can reach a high prograde circular orbit, a frozen orbit, or an elliptical orbit, but only marginally. NASA won't want that. So realistically Orion will never be sent anywhere other than NRO, EM-2, or a distant retrograde orbit. NASA will always want an abort-to-Orion option, so Orion cannot be moved around by a tug.

Everything else will need to be emplaced by commercial rockets, and it will need to be sent well in advance.

It's also generally agreed that we are targeting the poles.

So those are the constraints:

1. Stage a polar lunar surface mission,
2. Using commercial rockets to place everything in advance,
3. At NRO, EM-2, or DRO,
4. Permitting no more than an 8-tonne module to arrive along with Orion,
5. And without moving Orion after it arrives.

Aaaand....go.

Not much better.

Edited February 11, 2020 by sevenperforce