Eyes Turned Skywards

...
Anyway, to address the underlying question, the fairing is long enough to comfortably contain Pegasus, a lander, and an Apollo capsule up at the taper, with the Apollo itself exposed in position for abort if required. The image just needs some tweaking to reflect this. :)

But, since this one lacks an escape tower, I'm assuming it is for the unmanned hab/lab. The manned version with the CSM/LEM will be the last launched so we'd hardly expect to see it yet!

It would seem the existing picture is good enough for now; any revisions suggested will result in perfection for the manned launch!:)

I can always suppose a 1990s Republican dominated Congress demanded the three flags!:rolleyes:

(I guess we're lucky the States' Rights faction didn't demand a Florida flag and a Texas one. maybe Alabama too).

Yep, when going over the Wiki page with the stage specifications I was reminded the booster and core stages differ in empty mass by two metric tons, presumably that's the truss structure the outer stages attach to.

And that got me thinking again, on further stretches of the Heavy concept. Don't worry about me asking about strapping on yet more booster stages again! (Yet!)

But instead of developing the -3 second stage, aka S-IVC, I wonder what stands in the way of simply stacking 3 Dash-2, that is S-IVB, each on top of the three booster stages. It seems clear enough that if one were to triple the payload the whole thing should follow the same ascent profile as an M02, but it gets better still if we stage the upper trio further--simplest approach being to simply fire the outer two but not the center one, then upon burnout of those two fire the central one bearing the payload. A bit fancier would be to cross-feed the outer two so the center engine also burns; burnout would be in 2/3 the time a single S-IVB takes, 262 seconds instead of 393, so gravity loss would actually be reduced in that stage; I estimate the savings there would almost offset the near 800 m/sec the extra burn time of the central stage would add.

For a 185 km, 28.5 degree orbit, the crossfeeding version could loft over 104 tonnes, I figure (based on kludging around with a multiplier of the payload for an M02 until I get the same mission delta-V for the 3 phase version I get for the vanilla M02). I think the ratio gets even better when we go for more energetic orbits--almost 63 tonnes to a transfer orbit to geosynch for instance. Even without crossburning the extra boost time and associated gravity loss should not cost more than a couple tonnes of payload out of these very large figures.

It seems much too good to be true, but the math seems sound to me.

That would not be the ultimate Multibody hubris, but it is amazing how just sticking to three bodies side by side we can not only approach but match Saturn V performance, with fewer than 3/5 the number of rocket engines.

I don't see any showstoppers to prevent such a stack being assembled; each Multibody first stage unit, whether an S-1F-2 core design or an S-1G-2 outer booster design, should have no trouble bearing an S-IVB on top. Some kind of force transfer truss akin to that used in S-1F-2 has to be incorporated into the central S-IVB, but that should be no problem for the designers of the H03! It would stack no taller than an H02, unless the payload itself extended rather far up, but there is plenty of margin in the VAB. An example bearing an entire 104 tonne payload would mass 2056 tonnes, but that is just 100 more than an H03 bearing 84 tonnes for 185 km orbit, so that doesn't seem extreme. With payload but without fuel, as the two would be moved on the crawler to the launch pad, the difference is just 28 tonnes, 228 versus 200, and that difference is mostly the greater payload.

So, while it might lie outside the limits of the timeline, is there some reason I have overlooked such a further stretch, an H04 if you will, is ruled out on engineering grounds?
 
Superb use of light to achieve photo-realism on this one, Nixon. A perfect addition to the timeline.

Thanks! It's amazing what flaws can be hidden by shrinking the size of the image ;)

The Saturn H03 widebody fairing developed for Freedom is 10m in diameter and about 20m long in the barrel alone--it had to carry the 27m long Freedom truss segments. Pegasus is about 10m overall with the various payload adaptors, and the lander is another 8 or 9 (I don't have measurements off of Nixonshead's final models, so he'd have the final data on that). If anything, Artemis might use a slightly shorter version of this monstrous fairing, with about an 18m barrel. However, I just checked, and the wiki representation of the Multibody doesn't have the proper fairing length (it's only a 16m barrel or so), so this might be wrong on Nixonshead's model through my failure to update the image.

Indeed, I worked from the Wiki image, so it seems the fairing is a bit short :( The Saturn Multibody started as a bit of a side project for me, which I started modelling on my laptop one evening during a ski trip, so I must admit I skipped some of my usual checks. Also I must admit some of my motivation for getting this out this week was to have something up on the Air and Space thread to try to canvas for votes :rolleyes:.

I shall endeavour to correct these details for a future post - perhaps at the same time I add Multibody to the 'rocket park' :) At that time I'll also double-check the space for the Pegasus-lander stack.
 
Part III, Post 20: The banker's bet and the Artemis 4 cargo lander flight
Good afternoon, everyone! It's that time once again, and I know this is a moment a lot of you have waited a while for, so I'll keep this brief. First, if you haven't already voted in the Turtledoves, I'd once again like to say that if you enjoy this TL and the artwork that Nixonshead has brought to it, please support us here and his artwork here. Thanks for all the support you've given this timeline, and without further ado, I hope you enjoy this week's post! :)

Eyes Turned Skyward, Part III: Post #20

With the completion of the Artemis 3 test flight and Administrator Davis’ decision to take the “banker’s bet” approach to Artemis 4 in June, the next Saturn Heavy launch became a matter of intense focus for NASA’s mission control staff in Houston, and its launch staff in Florida. For many of the staff whose entry into the program had come close on the heels of the abandonment of Apollo, the day they had waited so long for and had, in some cases, feared would never come was finally at hand. Foremost among these individuals was the mission’s commander, Don Hunt. Joining NASA’s astronaut corps in 1978, he had served alongside veterans of the moon landings even as many of them had been preparing to leave for greener pastures. Through NASA’s years of focus on space stations, Hunt had built a reputation as a smart flyer and a cool operator--perhaps best exemplified by the famous radio calls during the “rough ride” of Spacelab 28. Though others like John Young had more overall seniority, by 1998 Hunt was the most senior astronaut still flying. His selection as the commander of the first Artemis manned landing was a reflection of this extensive experience, though his relatively strong name recognition was also appreciated by the Public Affairs Office. However, his selection was also made with the understanding that this would be his final flight. Just short of turning 50, he was on the verge of losing his flight status, to the Moon or anywhere else for that matter. As it was, he would be the oldest astronaut ever to fly to the Moon, two years older than Alan Shepard on Apollo 14.

Hunt’s reaction to the knowledge that this was to be his final mission was to throw himself into all aspects of planning--he pushed his chosen crew hard on flight training, encouraged their involvement in the preparation of both the manned and unmanned landers, and threw himself into the geological portions of the DREAM desert training exercises with enthusiasm. The pilot crew was filled out by pilot Natalie Duncan, on her second flight. They were joined by the Mission Science Officer, Ed Keeler. The MSO was a position that had evolved on Spacelab and Freedom. In order to coordinate the stations’ scientific operations with ongoing maintenance and flight operations, the most senior flight scientist on-orbit was selected as the Science Officer, with the responsibility of working with the station command and ground engineers to plan work schedules and ensure that the station’s scientific missions did not get overshadowed by operational concerns. The concept was adapted for Artemis, with the MSO having more specialized geological training and essentially serving as the executive officer of the flight, with near-equal responsibilities to the commander while on the surface. While the commander was responsible for seeing that the mission was safe and successful, the MSO was responsible for seeing that it was scientifically productive. The final crew member of the foursome was the Artemis program’s first international partner, cosmonaut-selenologist Luka Seleznev, of Ruscosmos. The symbolism of a Russian accompanying a crew of Americans to the Moon was palpable, an ironic contrast to the fierce competition between them in the (first) Space Race of the 1960s, and also evocative of the entreaties for Russo-American cooperation featured in Arthur C. Clarke’s Odyssey novels. And things certainly got off on the right foot: as training proceeded, the crew quickly established a rapport--Hunt and Keeler shared a fondness for puns, which contributed to the typical EVA pairings: Seleznev would pair with Hunt while Duncan would accompany Keeler--according to an exasperated Duncan, it was the only way to stop the punsters from filling the radio. The relative jocularity of the crew proved an asset during the long hours of training and the multitude of tasks facing them while the spotlight of public interest focused on Artemis.

As the hundreds of engineers and technicians involved in the program completed their preparations and reviews, the first Moon-bound Artemis launcher was rolled to the pad on crawlerback on November 18th. Once its impossibly slow journey was complete, pad crews connected the Mobile Launch Platform to ground services, and began the multi-day process of leak checks, wet dress rehearsals, and final payload checks. Meanwhile, the crew assembled at Houston to witness the launch--Hunt was determined to set the precedent that, in spite of being unmanned, Artemis cargo landers would be just as much the responsibility of the crews which would use them as their own Apollo spacecraft were. One example of this was his decision, after consulting with his crew, to provide a callsign for the lander. In the discussions, the crew selected the name Janus, referring to the Roman god of endings, new beginnings, and choices--an apt moniker for a spacecraft with as much riding on it as the “banker’s bet,” the beginning of the Artemis landings, and the end of Hunt’s flying career. On November 23rd, preparations began for the first launch attempt. Ice and frost accumulated on the skin of the oxygen and hydrogen tanks as the massive vehicle was fueled and prepared for flight. However, those at KSC to watch the launch were to be disappointed, as diagnostic telemetry from the Pegasus and lander inside the fairing began to malfunction as the countdown reached T-25 minutes, resulting in intermittent failures to receive data and some indications of temperatures and pressures inside the fairing and the vehicle that were well outside normal limits--and in some cases outside expected physical possibility. In order to fix the issue, the launch attempt was scrubbed, and the count recycled for the alternate date--November 27th.

In spite of the Thanksgiving holiday, pad crews, launch team members, and support in Houston worked to diagnose and resolve the issue, tracing the problem to a marginal wiring harness in the connection carrying the telemetry from the rocket to the launch tower during the countdown. The overtime during a holiday wasn’t something NASA typically did in the era of Freedom, but lunar launch windows paid no heed to human customs. With the issue resolved and the wiring replaced and retested, the launch team gathered again on the 27th. This time the Saturn Heavy soared into the sky on a fiery plume and a wave of thunder. In stark contrast to the issues on the pad, the launch itself was perfectly nominal from the moment the engines lit and the hold-downs released to the completion of the Pegasus’ contribution to ascent. After a short coast, the stage relit to complete the injection of the Janus lunar module. During the three-day coast to the moon, mission control carefully monitored the temperatures and pressures of the descent stage, providing the final proof to Artemis 2 and 3’s data about the successful extended storage of cryogenic fuels during the trans-lunar coast. Hunt requested a break in the training schedule to allow his crew to take shifts in Houston’s Mission Control Center, following Janus through its long coast and the trajectory modifications to put it on course for its descent to the lunar surface.

The landing site for Artemis’s first lunar return had been a topic of heated debate within the program. With just six landings planned in the initial sequence, lunar scientists were determined to maximize the scientific return of Artemis and advocated for a wide range of initial landing sites--many with interesting surface features that, unfortunately, also created tricky landing approaches. Flight planners, on the other hand, were more interested in verifying the correct performance of lander systems during the first flight, implying the selection of a relatively flat and topographically uninteresting landing site which the automatics (and still more the human pilots) would have little trouble with. In turn, scientists opposed the possibility as such sites were also likely to be geologically uninteresting and yield less new data even with the extended stays of Artemis than their preferred sites. Political interests also factored in, as the President was interested in a return to the moon which would highlight American leadership in a post-Christmas Bombing world as an example of unity. Although far from a directive from on high, certain administration officials had inquired about the possibility of mounting a return to one of the Apollo landing sites, hoping to mine nostalgia among the politically influential Baby Boomer class for the period and find a graphic example of American technological leadership, both past and present, to display for the world.

As leaders of the flight crew, with ultimate responsibility for actually flying the mission, Hunt and Keeler actively participated in these discussions, with Hunt tending to lean on the side of the flight concerns, while Keeler naturally had sympathies for the scientific concerns. However, unlike most of the members of these factions, Hunt and Keeler worked together extensively during their training, and eventually came to see much of the other’s positions--Hunt could see where and why geologists were interested in the Moon, while Keeler’s NASA flight training (a requirement even for non-pilot astronauts) meant he understood the engineering concerns about the first landing. In the end, the pair came to a mutual agreement that they took to the site selection board meetings together and managed to sell--Keeler suggested visiting one of the early Apollo sites, one where the geological potential had not been exhausted by extensive roving EVAs. In particular, the suggestion was to land at Apollo 12’s landing site in the Ocean of Storms. While the site had been explored by Pete Conrad and Al Bean, to say nothing of the earlier Surveyor 3 lander, there were still unanswered selenological questions about the area, many of which had actually developed from Apollo 12’s efforts. Compared to other areas of the near-side, the Apollo 12 site was relatively young, as much as half a billion or more years younger than the Apollo 11 site, and had a number of interesting chemical properties. It had also been the first location on the Moon where KREEP, an unusual combination of potassium (K), rare earth elements (REE), and phosphorus (P) had been discovered, although only a single sample. As the Lunar Ice Orbiter and Lunar Reconnaissance Pioneer had discovered a significant enrichment of KREEP underneath Procellarum, there was considerable interest in better characterizing the surface abundance of the combination there. Additionally, the Surveyor and Apollo 12 landing sites themselves could provide an interesting survey site; much as Conrad and Bean’s mission had produced data about the results of years of exposure on the lunar surface, a return to the Ocean of Storms would be able to take observations of the effects of nearly 30 years of continuous exposure to the lunar environment.

With the deadlock broken, the final site selection was made in early 1998, with maps from the Lunar Ice Orbiter and LRP being tapped to map a final landing site and program Janus’s flight computers with topology data. In order to minimize effects on the Apollo 12 site, the landing target for Artemis 4 was over a slight rise, several kilometers away--well within roving range, but enough to avoid unnecessary impact to the site, and exposing a new area to easy EVA access. On November 30th, Janus followed along its programmed course, firing its descent engines for the first time to slow its interplanetary trajectory. With no need to leave a spacecraft in lunar orbit, no propellant was spared to enter a temporary orbit; instead, Janus fired to drop directly into its final landing trajectory. As they had gathered for the launch, Hunt’s crew gathered at Houston for the landing, watching the telemetry and video from the lander as it began its autonomous descent to the surface. Tension in the MCC was high, and without a crew onboard to relay observations, the descent had more in common with the final descent of the JPL Mars Traverse Rovers in 1995 than the Apollo missions. As it moved through the descent phases, Janus transmitted back codes indicating the status of its internal descent logic, to compare in Houston to the transmitted telemetry.While not as drastic as the 15-minute delay in data from Mars, the two-second light lag was enough that Janus was entirely on its own in piloting its descent.

Sighs of relief and scattered applause broke across the room as the data confirmed that the lander had acquired the ground with its radar at just over 20 km, then again as the data was matched to its onboard maps and the lander began adjusting its descent to make the minor corrections to steer to the landing site. On the cameras fixed on the descent stage, the Moon loomed large, going from a globe to rapidly rising surface. As the surface of the Ocean of Storms rose to meet it, Janus cut down its speed, then cut out its outboard engines to continue the burn on the center engine alone. As the fuel burnt off and the speed and altitude dropped still lower, that single engine too had to be throttled to control the descent acceleration, exactly matching the lunar gravity to proceed at a constant rate. Finally, Janus signalled back that it had selected a final landing location, and was descending to it. In the Mission Control Room, the horizontal speeds dropped and nulled out as the lander steadied itself hundreds of meters above the site, and began its terminal descent. A plume of dust obscured the ground as it dropped the last few meters, increased at the last moment as the lander’s engine fired to kill its vertical speed. At a meter up, probes on the footpads hit the surface, and the engines automatically died as the lander dropped. Seconds later, the MCC staff watched the critical codes come back--Contact! Engine off! Acceleration readings on the stage jumped as it crunched into the lunar soil, then settled--the lander was stationary. As the room broke out in cheering, the grinning guidance controller turned to the flight director. “Platform is stable, and we are down on the moon!” Joining in the applause, the launch control loop captured Hunt’s words as he leaned over to talk to his MSO. “Well, Ed, what do you say. Feel up for a little camping trip next year?”

When the Flight Director was able to restore order to the room, the Mission Control staff began the process of configuring the lander for surface operations, converting it from a spacecraft to a stationary facility. Valves in the descent stage were opened to purge the remaining hydrogen and oxygen from the tanks, reducing the internal pressure of the propellant tanks and the risk of a rupture. Readings were also taken to determine the final landing site, which determined that Janus had steered itself to within 800m of the center of the targeting ellipse. In addition to this accuracy, the computer’s landing had been more economical than expected performance, meaning that there were substantial quantities of residual propellant remaining in the tanks. The Lunar Crew and Logistics Module had been designed to carry 14.5 tons with margin, but now Janus had shown that this margin might not be entirely necessary. Accordingly, Boeing and NASA engineers began analysis on how much extra payload could potentially be carried on future flights it such economy could be replicated. In the meantime, Janus was commanded to spread its solar arrays to catch the light of an early lunar morning and charge its fuel cells for the long, cold lunar night. Over the next few months, it would keep a solitary watch over the future Artemis 4 landing site while Hunt’s crew prepared for their mission and the vehicles that would join it were processed for flight. Administrator Davis’ bet had paid off, and the Artemis lander had passed its final testing hurdle. All that remained was for its crew to join it on the surface of the moon.
 
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Yep, when going over the Wiki page with the stage specifications I was reminded the booster and core stages differ in empty mass by two metric tons, presumably that's the truss structure the outer stages attach to.
It's more that some of the stringers and other structure in the tank that supports the extra mass of the upper stages can be omitted on the boosters.

I don't see any showstoppers to prevent such a stack being assembled; each Multibody first stage unit, whether an S-1F-2 core design or an S-1G-2 outer booster design, should have no trouble bearing an S-IVB on top. Some kind of force transfer truss akin to that used in S-1F-2 has to be incorporated into the central S-IVB, but that should be no problem for the designers of the H03! It would stack no taller than an H02, unless the payload itself extended rather far up, but there is plenty of margin in the VAB.

So, while it might lie outside the limits of the timeline, is there some reason I have overlooked such a further stretch, an H04 if you will, is ruled out on engineering grounds?
The concept of clustering cores for upper stages is not a new one, and in this case it wouldn't run into stacking issues--as you say, it's not a particularly massive stack, and well within VAB and pad limits. However, the issue it runs into is with staging. The cores off-center create some different loads, and unless each stage is supported by a core directly and includes multi-axis connections (that is, it's not just as simple as a pad for the core to push up against, you also have to have some bolting to hold the core to the upper stage) you'll get some rather interesting bending moments and torques. If you do bolt them, then you avoid that, but instead get some issues with staging--if you stage the booster cores before the core (throttling down the core to improve performance), you're much more restricted in the mechanics of the booster separation. If not done carefully they will have issues with contacting the upper stage above them. Moreover, the center core is then back to lifting the entire upper stack itself and you've got an interesting aerodynamic load problem again on top of the existing bending moments and torques. If you do stage the entire lower core cluster as a single unit, then you run into fewer issues but you lose performance. If you can get past those issues, staging the upper stage boosters off isn't a particularly daunting challenge--analogous to staging off the side boosters of a conventional heavy but without as much atmosphere complicating things.

In the specific case of Saturn Heavy for Freedom or Artemis, a triple-core upper stage also has the disadvantage of requiring more effort to prepare. A standard M02 requires two lift operations and a single mate to be ready to receive payload. Saturn H03 requires four lifts and three mates. Saturn "H04" would require six lifts, and five mates, with two of those being the upper stages that will require more precision. There's also more connections, pyros, and hardware in general to fix up. There's ways to deal with all of this, but in the case of Artemis...Akin's Law #39. It's just another of those things far easier to do in Kerbal than in real life.
 
Great update - really enjoyed reading especially the discussion around landing sites. Interesting that they are going back to the Ocean of Storms. It also looks like they might have more payload oppurtunities on later missions.

Minor quibble. John Young retained Astronaut flight status in or TL until his retirement in 2004. I don't really think at Age 50 a astronaut loses flight status, Story Musgrave flew at age 61 and Vance Brance 59 and Shannon Lucid 53.

I have a question about Power. So with Solar Panels and fuel cell combination are you using the solar panel to take the water from the fuel cells and separate back out into liquid Oxygen and Hyrdogen?
 
Great update - really enjoyed reading especially the discussion around landing sites. Interesting that they are going back to the Ocean of Storms. It also looks like they might have more payload oppurtunities on later missions.

Nostalgia reasons certainly helped picking an already landed-on landing site, combined with already having a good knowledge of the area.

I agree, the more useful payload they can eek out of their Habitat the better.


Minor quibble. John Young retained Astronaut flight status in or TL until his retirement in 2004. I don't really think at Age 50 a astronaut loses flight status, Story Musgrave flew at age 61 and Vance Brance 59 and Shannon Lucid 53.

I think that has to do with the greater physical requirements of the Lunar Environment. Multiple EVAs, heavy suits with lots of life-support, it puts a lot of stress on the body. And IIRC, John Young last flew in the late-80's IOTL and simply had Flight Status until he retired.


I have a question about Power. So with Solar Panels and fuel cell combination are you using the solar panel to take the water from the fuel cells and separate back out into liquid Oxygen and Hydrogen?

I suspect that that's the general idea, split the H2O back into H2 and O2 with the surplus power during the Lunar Day to sustain the Habitat during the equally long Lunar Night.
 
Nostalgia reasons certainly helped picking an already landed-on landing site, combined with already having a good knowledge of the area.

I agree, the more useful payload they can eek out of their Habitat the better.




I think that has to do with the greater physical requirements of the Lunar Environment. Multiple EVAs, heavy suits with lots of life-support, it puts a lot of stress on the body. And IIRC, John Young last flew in the late-80's IOTL and simply had Flight Status until he retired.




I suspect that that's the general idea, split the H2O back into H2 and O2 with the surplus power during the Lunar Day to sustain the Habitat during the equally long Lunar Night.

I do agree about multipe EVA's and the physical requirements. I mean 1/6 gravity helps but you still have to for example flex your hands against a pressurized suit to just grasp a tool. My point was that age 50 isn't a magic cutoff that you don't fly anymore.

The EVA got me thinking about how EVA's will be handled. I would assume that you cannot have somebody doing back-to-back EVA's over 14-days. On the J missions they have 3 EVA's over 3-days but then they where done. I would think that some stand-down days will be built in to allow the astronauts to rest. I know reading Gene Cernan's book "Last Man on the Moon" he mentioned how beat up he felt by the end of the 3rd EVA. How the lunar dust would get on your fingers back in the LM and then get beneath your finger nails and feel like splinters where being hammered under your nails. Still waiting to see how dust problems are handled since the SpaceSuits will be exposed to lunar dust over a longer time period.

As far as power I am little confused. I thought earlier I did read that batteries where being used with solar panels. However now it sounds like Fuel Cells are being used with Solar panels. If Fuel cells are being used why the explusion of residual propellant of Liquid O and H after the landing? I would think you would keep that since it can be used for the fuel cells.
 
....
I have a question about Power. So with Solar Panels and fuel cell combination are you using the solar panel to take the water from the fuel cells and separate back out into liquid Oxygen and Hyrdogen?

...
I suspect that that's the general idea, split the H2O back into H2 and O2 with the surplus power during the Lunar Day to sustain the Habitat during the equally long Lunar Night.

I was wondering about that too. Is it easy to simply run fuel cells backwards, applying an externally generated voltage to reverse the reaction and bubble out hydrogen and oxygen?

Chemically I think that's child's play--indeed a major risk on pre-nuclear, WWII (and WWI I guess) era diesel-electric submarines was that charging lead-acid batteries could also release hydrogen, creating dangerous levels of hydrogen and thus an explosion hazard in the closed chambers of a submerged ship. The question would be whether the complex electrodes of a fuel cell would be degraded by reverse operation or not.

There are also questions of efficiency--presumably one loses some power each way, and perhaps a lot more running in reverse? But that's OK if there is plenty of input power available; during Lunar daylight there should be little need for an idled lander waiting for the mission to arrive to use much power for housekeeping, so all the solar power is available for electrolysis; it won't matter much if ten or 20 percent gets wasted as heat, unless the heat itself, combined with the module being heated by direct sunlight and the warming regolith around it, becomes a problem to get rid of. The module will always have a shaded side; if the landings can always be precise enough so the designed "cool" side faces the nearest pole it will always be in shadow (maybe with more of it exposed at dawn and sunset, but the heating problems will be less then--at dawn the regolith is chilled down, at sunset the cell reactant tanks have had 2 weeks to fill up and shadows lengthen on the ground, while the lower angular incidence of the Sun means that the surface is being less intensely heated even where exposed so it should be cooling off--not so much the vertical surfaces of the module that happen to face west, but overall the input heat is lower and the module is idle. Indeed late "afternoon" heating might be welcome if it can be shunted into heat sinks that help keep the craft warm without power draw (or just a little for thermal circulation) some time after sunset.

There is one more issue that comes to mind regarding reversible fuel cells--typically fuel cell reactant is stored as cryogenic liquids; if we are producing hydrogen and oxygen from water, we need to store the stuff somehow. If we can manage to liquefy it, then once the sun is down keeping even the hydrogen cool enough might not be too difficult, getting easier as the regolith surface cools down--besides at that point we are using it to keep other parts of the module warm enough. But that first step is tricky! Hard enough for oxygen and harder still for hydrogen; we might, I would guess, use a lot more solar power trying to compress (and thus, through radiating the heat from that, cool) hydrogen to the point where it liquefies than the power potential it represents as reactant. Again not such a problem if we have lots more power available than we need to store for overnight, but we also need the equipment to do it; compressors are not lightweight, is my impression!

Otherwise I'd have been picking up on the hint the previous canon post (IIRC) dropped with the word "depot," which I took for foreshadowing of things to come. The various rescue craft schemes I was going on about would have been much more viable if only they could have used hydrogen-oxygen propellant--which only could work if there were a means of continually reconditioning the evaporated hydrogen back into liquid.

On the Moon it is somewhat easier than it would be in orbit since gravity is a help in settling out the liquid hence processing and storing it; also the quantities of reactant needed for a fuel cell are much less than those needed for significant delta-V.

But consideration of the problems of reprocessing water back into cell reactant seemed serious enough that I had been assuming up to this point that power storage or generation had to happen some other way, with any fuel cells on either lander being reserved for actual mission operations and no consideration of recharging them--the idea in STS mission usage, which certainly could have developed the option of recharging, was instead to use up the reactant and then make the water available to the crew to drink, wash and cook with.

There is an alternative to liquefying the gases--one could consider storing them in gas form! The problem there is clearly first of all that masses of oxygen, and still more hydrogen, will occupy very large volumes indeed at moderate pressures. To give an idea, the use of helium in blimps does require a bit of overpressure--to an extent, overpressure is inherent in the whole concept of buoyant lift, since the displacement force appears in the form of pressure on surfaces, namely the upper surface of the gas cells. In addition to that, "nonrigid," AKA "pressure," airships (that is, blimps, as well as semirigids such as the modern Zeppelin NT) require overpressure, in the nonrigid case to provide all the structural rigidity, in the semirigid case at least to put stabilizing tension on the aerodynamic hull surface that otherwise would develop drag-causing ripples in flight.

The degree of net pressure is pretty low though--this is why I tear my hair out when Internet sources misinform the public that blimps have ballonets so they can vary the density of the lift gas and thus control net buoyancy!:eek::mad: This does happen to a very tiny extent, and the density of the gases inside the hull does vary--but only to match the changes in air pressure outside in the first approximation--the static lift of the helium does not vary significantly except insofar as thermal variations take time to come into equilibrium. The net gas overpressure versus the ambient air pressure is measured in single-digit percentages of net atmospheric pressure (traditionally in the USA, in "inches of water!" Where an entire atmosphere of pressure at sea level is something like 32 feet of water!)

Therefore if we were to seek to contain hydrogen or oxygen in ballonets made of the kind of lightweight fabrics generally used for modern airships, we'd be storing it at pressures far below Terran surface atmosphere pressure, requiring a hundred times the volume--multiplying volumes that are already huge at one atmosphere! I haven't done the math but I suspect the enormous surface areas of the fabric involved would more than offset the lightness per square meter. And generally speaking, if we reduce the volume by raising the pressure, while the area goes down dramatically so does the weight of material to handle the increased strain go up, so the ratio of fabric to mass of gas contained remains rather heavy, even if we go up to tens of atmospheres of pressure. Other things being equal we'd probably prefer a compact if heavy pressure tank storing gas at high pressure to a bloated huge balloon holding it at low pressure--we'll lose power pumping the gas into the high-pressure tank but at get that back drawing it out, whereas a low-pressure ballon will feed gas out sluggishly.

And of course, another factor to consider is that any balloons or tanks will be storing gas through the Lunar night; with a big surface area a ballonet would radiate heat and the gas would cool--this does not let us lighten the fabric though because it still has to be pumped in during daylight, when the fabric is picking up sunlight. So it would cool and the pressure would drop overnight, possibly the temperature would fall so low the stuff would start to liquefy despite low pressure! I can imagine a clever design involving support frames that can guarantee the liquid pools above the inlet/outlet, but that is more weight and more to the point with an unmanned lander, a gadget that either has to be set up by some kind of robots or built into the module structure somehow.

So--I expect that if there is not going to be an effort to actually reliquefy the reactants, instead bulky but not extremely heavy gas tanks will be provided to store the gases at high pressure. But this is rather awkward!

Depending on how heavy and power-hungry equipment to reliquify the hydrogen would be (if you can chill hydrogen like that then liquefying the oxygen is child's play in comparison, involving a simple heat exchanger) it might be more economical in mass overall to go ahead and do that, reusing the original fuel cell reactant tanks. Such a capability also guarantees capacity to keep the module cool during daylight operations.
 
I do agree about multipe EVA's and the physical requirements. I mean 1/6 gravity helps but you still have to for example flex your hands against a pressurized suit to just grasp a tool. My point was that age 50 isn't a magic cutoff that you don't fly anymore.
The text doesn't say that it is. However, while the US is putting in more manhours in space ITTL, those hours are spread over a lower number of individuals. IOTL, there were 6-8 Shuttle missions a year through the 90s, or about 42 to 50 seats. ITTL, there's only 4 rotations of 5 crew to Freedom. ITTL, an astronaut flies longer in space in their career, but fewer overall missions. There's less open space for older astronauts to fly if upcoming pilots are to be given a chance to get flight experience.

The EVA got me thinking about how EVA's will be handled. I would assume that you cannot have somebody doing back-to-back EVA's over 14-days. On the J missions they have 3 EVA's over 3-days but then they where done. I would think that some stand-down days will be built in to allow the astronauts to rest. I know reading Gene Cernan's book "Last Man on the Moon" he mentioned how beat up he felt by the end of the 3rd EVA. How the lunar dust would get on your fingers back in the LM and then get beneath your finger nails and feel like splinters where being hammered under your nails. Still waiting to see how dust problems are handled since the SpaceSuits will be exposed to lunar dust over a longer time period.
The plan is for some kind of interspersion of EVA days with "stay-home" days. During these days off, the crew has a chance to catch up on maintenance of suits and the hab, work in the lab on basic analysis of samples in the habitat's geology lab, and generally recover from the effort of EVA.

As far as power I am little confused. I thought earlier I did read that batteries where being used with solar panels. However now it sounds like Fuel Cells are being used with Solar panels. If Fuel cells are being used why the explusion of residual propellant of Liquid O and H after the landing? I would think you would keep that since it can be used for the fuel cells.
It's batteries and panels for Apollo, batteries alone for the descent and ascent stages, and solar/fuel cells (with electrolysis recharge) for the habitat.

Since power during the exploration day periods is provided by the solar arrays, the fuel cells are mostly sized for the lunar night, and the reactant tanks and water storage is sized for this need. Using the residual propellants as reactant doesn't really provide much benefit--if the lander's fuel cells have kept it warm through the night, then their job is done and they're ready to recharge from the panels. Reactant margin doesn't help much there. Thus, there's not much point to including the complex plumbing to run any residuals to the reactant tanks. They ended up with more residuals than they thought, but they're preferring to take up that margin by landing more payload, rather than by using it as unnecessary buffer for the heaters.

Oh, and Shevek: regenerative H2/O2 fuel cells were something NASA was doing IOTL with the Helios long-duration aircraft around 1999. Since fuel cells are really the only option short of a nuke (we looked at a TOPAZ, but the political issues are shaky internationally and domestically), they're just pushing this tech. Shuttle only wanted about two weeks duration in space from the vehicle, so my guess is they never found regeneration worth the expense of modifying the system. As for reactants, the plan is to only gassify them. At a standard gas storage pressure of a dozen MPa or so, it's only a few cubic meters for the couple hundred kg of reactant we need. Why spend more energy to liquefy it when we'd only need to then worry about boil-off and warming it back up to a gas in the cells?
 
The text doesn't say that it is. However, while the US is putting in more manhours in space ITTL, those hours are spread over a lower number of individuals. IOTL, there were 6-8 Shuttle missions a year through the 90s, or about 42 to 50 seats. ITTL, there's only 4 rotations of 5 crew to Freedom. ITTL, an astronaut flies longer in space in their career, but fewer overall missions. There's less open space for older astronauts to fly if upcoming pilots are to be given a chance to get flight experience.

The plan is for some kind of interspersion of EVA days with "stay-home" days. During these days off, the crew has a chance to catch up on maintenance of suits and the hab, work in the lab on basic analysis of samples in the habitat's geology lab, and generally recover from the effort of EVA.

It's batteries and panels for Apollo, batteries alone for the descent and ascent stages, and solar/fuel cells (with electrolysis recharge) for the habitat.

Since power during the exploration day periods is provided by the solar arrays, the fuel cells are mostly sized for the lunar night, and the reactant tanks and water storage is sized for this need. Using the residual propellants as reactant doesn't really provide much benefit--if the lander's fuel cells have kept it warm through the night, then their job is done and they're ready to recharge from the panels. Reactant margin doesn't help much there. Thus, there's not much point to including the complex plumbing to run any residuals to the reactant tanks. They ended up with more residuals than they thought, but they're preferring to take up that margin by landing more payload, rather than by using it as unnecessary buffer for the heaters.

Oh, and Shevek: regenerative H2/O2 fuel cells were something NASA was doing IOTL with the Helios long-duration aircraft around 1999. Since fuel cells are really the only option short of a nuke (we looked at a TOPAZ, but the political issues are shaky internationally and domestically), they're just pushing this tech. Shuttle only wanted about two weeks duration in space from the vehicle, so my guess is they never found regeneration worth the expense of modifying the system. As for reactants, the plan is to only gassify them. At a standard gas storage pressure of a dozen MPa or so, it's only a few cubic meters for the couple hundred kg of reactant we need. Why spend more energy to liquefy it when we'd only need to then worry about boil-off and warming it back up to a gas in the cells?

Just short of turning 50, he was on the verge of losing his flight status, to the Moon or anywhere else for that matter.

This is the sentence for me that implied the age 50 thing. However I must of read to much into it. In the grand scheme of things it isn't important.

I got the thought about using residual propellant for the fuel cell from a Altair Lunar Lander Consumables Management document. http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20090040458_2009038394.pdf The document mentions using residuals in the DM propellant tanks for the fuel cells. However the Altair lander is not using regenerative H2/O2 fuel cells.

I have to ask about the regenerative fuel cell. I have reviewed this paper from 1968 and it talks about a regenerative fuel cell for a moon base P302. http://www.boomslanger.com/images/1969020460.pdf Isn't this basically the exact same thing the Habitat is doing except this system also liquefies the H2 and O2?

An e l e c t r o l y t i c cell has been developed for space (or
lunar base) usage. This w i l l produce 3.43 kg H2 O/h.
of t h i s subsystem is 0.51 m X 0.41 m X 0.30 m (0.063 m ) with a mass of
93 kg. The hydrogen l i q u e f i e r has a m a s s of 340 kg and the oxygen liquefier has a mass of 141 kg. Development and cost of f i r s t unit is 100
The basic envelope 23 million dollars. Each additional unit w i l l cost 5 million dollars.
 
Saturn, while having almost the same diameter as Jupiter, carries a far lesser mass - ~95 times that of Earth compared to Jupiter's ~318 Earth Masses. This means that Jupiter simply has a much greater amount of Hydrogen can can be compressed to the point where it can enter its liquid-metallic state, which in turn means it can power a far greater magnetosphere, twenty times greater than Saturn is able to produce, though Saturn's is still close to 1,000 times greater than Earth's.

Additionally, Saturn has those big old rings, which happen to orbit just about where you would expect any radiation belts to be, so they sweep up any charged particles that do get trapped pretty quickly. All in all, Saturn is a much less hostile environment than Jupiter.
 
An0OG8f.png
 
Essentially. You have a Skipper under that second stage, or a Poodle? With those Mainsails so lightly burdened, I expect you make it to altitude pretty quickly, but then they burnout fast. I'd be inclined to try a Poodle for the higher ISp and fly a lofted trajectory with late gravity turn, but the Skipper's improved T/W might carry the day by allowing a lower turn and less gravity loss.
 
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Essentially. You have a Skipper under that second stage, or a Poodle? With those Mainsails so lightly burdened, I expect you make it to altitude pretty quickly, but then they burnout? I'd be inclined to try a Poodle for the higher ISp, but the Skipper's improved T/W might carry the day.
Skipper

(I didn't test it making a full flight to orbit; I just wanted to make this screenshot.)
 
Fantastic update, gentlemen.

Been waiting a long time for this.

Seems quite logical to pick a safer, more known site like Apollo 12 for the first mission, which really has to prove that all the hardware really works as advertised.

They can get more daring on the later sorties. Like, one hopes, at least a couple of polar sites with high water potential.

The plan is for some kind of interspersion of EVA days with "stay-home" days. During these days off, the crew has a chance to catch up on maintenance of suits and the hab, work in the lab on basic analysis of samples in the habitat's geology lab, and generally recover from the effort of EVA.

So would the schedule be alternating days for each two-astronaut team? Day on/day off/day on/etc., with the "off days" not so much "off" as used for recuperation and preliminary analysis of samples and data? How many EVA's per day? I'm curious what how long the life support is now on the new suits designed for the lunar surface.
 
Additionally, Saturn has those big old rings, which happen to orbit just about where you would expect any radiation belts to be, so they sweep up any charged particles that do get trapped pretty quickly. All in all, Saturn is a much less hostile environment than Jupiter.

You're back!!

I never heard that, about the ring material absorbing the GCRs and solar stuff (which would be attenuated by inverse square law that far from the Sun anyway to be sure).

It makes me wonder if the ongoing bombardment of GCR particles would produce a remarkably high concentration of transuranic elements in the rings. Most of these would decay very very fast to be sure (leaving a high concentration of familiar heavy metals) but there is talk of possible "islands of stability" for some isotopes. These would be vanishingly rare along the normal spectrum of elements formed by supernovas, but given time to accumulate, might they be found in observable concentrations in the rings?

Niggling against that is the notion I have from somewhere that the rings can't be a long-term phenomenon, that they must have formed pretty recently and are being rapidly dispersed, scattered by perturbations into higher orbits where they either leave Saturn's system completely or collide with the moons, or down to be absorbed by Saturn itself. If there have only been millions, or even thousands, of years they have been sitting there, I'd doubt much exotic stuff could have been formed.

Still, it's yet another reason to send more elaborate probes to Saturn, including some that can take samples of the ring material and analyze them, Fine dust would be just as good as chunks of big rocks for that purpose I guess, and easier to get--though of course such a prospector probe would be working in a rough environment, due to the greatly elevated incidence of micro-collisions and the higher chance of a major one.

It also raises the interesting if grandiose prospect of moving a fair sized asteroid (or armada of smaller ones) into Jovian orbit and blowing them up to make an artificial ring for Jupiter, then letting that stuff absorb Jupiter's mega-Van Allen belts and thus rendering the Jovian system more hospitable (barring the new navigational hazard of the rings of course!) for human operations.

Well, obviously such E. E. Smith space opera projects are out of bounds for this TL, but another, Heavy launched, superprobe to Saturn might not be.
 
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You're back!!

I never heard that, about the ring material absorbing the GCRs and solar stuff (which would be attenuated by inverse square law that far from the Sun anyway to be sure).

It makes me wonder if the ongoing bombardment of GCR particles would produce a remarkably high concentration of transuranic elements in the rings. Most of these would decay very very fast to be sure (leaving a high concentration of familiar heavy metals) but there is talk of possible "islands of stability" for some isotopes. These would be vanishingly rare along the normal spectrum of elements formed by supernovas, but given time to accumulate, might they be found in observable concentrations in the rings?

GCRs are too energetic to be trapped by Saturn's magnetic field (at the risk of stating the obvious, they had to be substantially non-affected by the Sun's magnetic field to even reach Saturn to begin with). And the island of stability is usually thought of in terms of isotopes lasting seconds, minutes, or possibly hours; not long, but much, much, much longer than other superheavy isotopes.
 
Morning all. So, Artemis 4 is underway! The intrepid cargo lander "Janus" has launched successfully, and Mission Control in Houston trigger the Pegasus stage's powerful hydrogen-oxygen engines to push the stack onto a heading for the Moon.

art4_TLI.png
 
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