First Light: The Journey of the Phthanophaneron

[problemecium]

First Light: The Journey of the Phthanophaneron

It turns out I've never actually done a mission to Moho. Shocking! I call myself a veteran, with well over 1000 hours (though I don't have records of this, I'm fairly sure) of play over the years since version 0.20.2, but I still haven't managed to actually "complete" the game as far as actually visiting all the objects available. Thus, since the transfer window to Moho is the first to occur in my new Career (after spending the first 110 days or so completing the tech tree by thoroughly scrubbing Kerbin, the Mun, and Minmus for Science), I'm taking the opportunity to document the adventure as a sort of refresher course for myself before taking on the Ultimate Jool-5 Challenge once more (since it's been literal years since I last put down the game).

For this expedition, I had been made aware that trips to Moho and back often take far more delta-V than one would expect, especially eschewing a gravity assist from Eve and the extra mission time that would entail, so I set my goal at 10 km/s and a maximum acceleration of at least 0.20 gees to avoid excessively long maneuver burns. I prepared what I considered the necessary payload and, based on its total mass, set about drafting some hull designs in the VAB, whereupon I discovered that the ship could certainly meet my needs, but it would be very, very large.

Some of you may remember my "Sights of Kidonia" thread from a few years ago wherein I built a grand mothership to tackle the Jool-5 Challenge. While I eventually finished orbital assembly and performed the ejection burn from Kerbin, while it was en route real life got in my way, followed by several updates to the game that altered part geometry and made some of the mission components unusable. The final fatal obstacle was that, once I picked up KSP again a few weeks ago, I discovered whilst doing a test run in a simple ion probe that Kidonia probably never would have been able to complete the full mission for lack of delta-V. It had been designed with just over 9 km/s in total, but that only meets the requirements of a Jool-5 Challenge mission nominally, i.e. in real life one is unlikely to pull off the mission with that much delta-V with extreme luck, extremely meticulous planning, or a lot of gravity assists and thus a very long mission time. In any case, this thing is... comparable in size and has less than half the payload mass. On the one hand, I'm pleased that this gives me an excuse to build an even huger ship for next time, but on the other, increased sophistication in KSP's code base appears to have made the game less performant when operating ships with enormous part counts, so it might be a taller order than I can handle.

But enough about Jool. This is a Moho mission! In this thread I'll be documenting the progress of the mission from start to finish and sharing my thoughts.

[problemecium]

Part One: Design

Phthanophaneron is the genus name of a group of flashlight fish and derives from Latin words for "the first to arrive" and "visible," hence it struck me as a poetic namesake for the first interplanetary voyage in my new Career and one to the "first" and most well-lit planet and thus the one on which seeing things should arguably be the easiest... probably nothing that needed explanation.

The mission concept is four basic components: A lander for exploring the surface of Moho and if possible the Mohole (and illusive southern Mohole), an orbiting station to serve as a long-term research base and home for the lander, an ISRU system to allow the station and its lander to replenish their resources, and a large mothership to carry all of the components to Moho and then return to Kerbin with the first batch of scientific results. This infographic explains more:

Yes, those are the real figures. As I mentioned above this ship is very large and approaches the old Kidonia in scale and complexity. It was planned to be assembled in orbit over the course of seven launches (though in practice more ended up being needed): The command and payload section, the drive core, the four side pods, and the payload. The latter is designed to be stowed and carried as a unit, but itself consists of a number of components:

The portable station core is designed to be a fully functional space station complete with relay antenna, mobile lab, housing for five Kerbals in total, reserves of all necessary resources, and a full suite of scientific instruments - and to stow within a single Mk3 Cargo Bay CRG-100 with no use of robotic parts so that it can be used by people who don't own the Breaking Ground DLC.
The light scientific lander attached to the core is designed to be (at least nominally) capable of landing on and ascending from Duna or any smaller object, most relevantly including Moho. It includes all scientific instruments except for the materials bay, and as a single stage, it can be refueled at the station and used again indefinitely.
The Ion Surveyor is what the name implies, an ion-propelled probe that can launch from the station and perform orbital resource surveys. This may come in handy locating the Mohole or any other Easter eggs that might be present.
The ISRU upgrade is a separate package that can attach to the core and itself stows within a Mk3 Cargo Bay CRG-25. It features a small reusable lander with mining drills to procure ore and a facility for storing and refining the ore on the station in the form of a storage tank, a small resource conversion refinery, and four radiator panels.

Because the mothership would be unreasonably large and heavy to launch as a single monolithic unit, it is designed as two central sections that can be augmented with up to four side-mounted drive pods. Each of these attaches via two docking ports to ensure alignment and structural stability, while the central components join each other via a larger array of five ports. In theory this same hull can be repurposed for other missions with variable amounts of delta-V and thrust based on how many drive pods are installed. Each drive pod itself weighs over 100 tons and has the necessary thrust and delta-V to power an interplanetary voyage singlehandedly, though it lacks a probe core or any other facilities for executing a fruitful mission.

At the front is a 10m Heat Shield. This isn't strictly necessary in the vicinity of Moho, but serves an aesthetic and roleplaying purpose as a debris shield and large dish to enhance the transmitting power of the communications antenna. Nestled under it are radiothermal generators, a large electric battery, the main control core, and four Science containers that allow the mothership to return to Kerbin on its own and deliver Science data from the mission. The ship isn't intended to land, but can rendezvous with a shuttle to retrieve the data and bring it to the Space Center.

The command and payload section does also include an array of eight solar panels, which shouldn't be necessary due to the presence of the RTGs but serve an aesthetic purpose and may provide auxiliary power during times of high usage such as aligning for maneuvers and performing scientific research while the lab is stowed.

I had the option of adding additional crew housing to enable the crew to return to Kerbin in the mothership or to bring additional crew members, but decided against it in the interest of minimizing payload mass. I can prepare crew rotation missions later to retrieve the initial crew and replace them with new members so that no Kerbal is doomed to a lifetime away from home.

Any questions or suggestions are invited! Stay tuned for orbital assembly.

[problemecium]

Part Two: Assembly

Confession time: I didn't manage to remember to catch screenshots of every critical part of the orbital assembly process. This is something I'll need to do for the Jool-5 Challenge later, so it was a good call practicing during this mission. Anyway.

The first component launched was the command and payload section. As it consisted almost entirely of an empty cargo bay, despite its size it was surprisingly light and easily handled by my 50 ton launch vehicle. It was placed in a 305 km orbit just above the threshold at which Kerbin's procedural terrain system deactivates and thus the game's performance is slightly improved. This has the added benefit of providing a generous margin for the periapsis to drift during the later ejection burn without it entering the atmosphere and causing efficiency loss due to drag, or worse.

Next the Drive Core was launched. I made a small oversight here: the drive core has no command modules and is thus unable to control itself, and the command and payload section has no propulsion systems. Thus the Drive Core was carefully parked near the command and payload section in a very similar orbit so as to minimize them drifting apart over time, and then a third launch brought up a heavy-duty space tug with RCS thrusters to maneuver the Drive Core and attach it to the command and payload section. The actual launch of the drive core was my first omission here; second was the attachment operation, which consisted of very carefully aligning all five of the docking ports seen here near the bottom of the image and docking them all at once. As is normal for such an operation, it was necessary to undock and re-dock a few times before all five ports attached properly.

Four more launches brought the Drive Pods into orbit. Seen here is the new 100 ton launch vehicle I developed to launch the Drive Core. Unfortunately, it was not able to launch either the Drive Core or any of the Drive Pods while they were fully fueled, and thus additional launches were planned for bringing fuel to the ship. Later, though, I instead decided to build an even larger 150 ton launch vehicle able to carry each Drive Pod all the way to a 305 km orbit and rendezvous with the mothership so that there wouldn't need to be too many extra launches, considering that the transfer window was already open and there were less than nine hours left before the optimal point in the middle of it. Disappointingly I neglected to capture any shots of the 150 ton vehicle at work.

Since, like the Drive Core, the Drive Pods lacked their own control or propulsion systems, installing them was a more difficult task than anticipated. They had been designed to have minimal extraneous parts, and thus had no extra docking ports to use for maneuvering them into place. I didn't want to use the Advanced Grabbing Unit ("Klaw") if possible, as past experiences have shown me that its use carries a risk of damage to the ship due to the parts tree being reorganized and rotation errors occurring due to the hinge on the unit, even if the hinge was kept locked the whole time. Thus what I had to do was detach each Drive Pod, leaving it to float on its own, and then painstakingly maneuver the mothership into alignment with its docking ports. This again required retries at a few points, but eventually I managed to get everything attached.
One last omission in this part was the launch and installation of the payload and the crew aboard it, which occurred just after installing the Drive Pods. Here, now that the payload has been installed safely, Benjamin Kerman, the engineer, has disembarked and is inspecting the docking ports, taking a close look at each pair to ensure they are all precisely aligned within a narrow tolerance. The most any pair deviated was a few barely visible centimeters, so with any luck this shouldn't be a source of issues.

Now that the ship was fully assembled, all that was left to do was to top off its fuel tanks before sending it on its way. It needed a total of about 16000 units, so multiple large fuel tankers had to be sent to accomplish the task. Two large fuel tankers, including the one shown here, handled the bulk of this, and then a third smaller fuel tanker (not pictured, sorry again) took care of the last bit.

Unfortunately I had made yet another oversight during this process and forgot to lock the fuel tanks on the payload or disable crossfeed on the port attaching it to its launch vehicle, and thus during the launch the vehicle had sucked most of the fuel out of it, and I didn't end up noticing until after the assembly was complete. Thus I had to have the third fuel tanker refill every single one of the numerous little fuel tanks on the landers and portable station core and then properly lock them, which was, as one might guess, very tedious and frustrating.
Do ALL the fuel transfers!
...Do all the fuel transfers?

BUT HEY, now it's (I'm pretty sure, I did check like four times) finally completely fueled (I even had the last tanker put a little bit of extra oxidizer in the mothership to give the scientific lander an extra load) and ready to depart for Moho! I ended up about nine hours late for the midpoint of the transfer window, which is doubly bad in light of the hours it'll probably take executing the ejection if I do it over multiple burns, but honestly it should have a minimal effect on the delta-V expenditure overall. This marks as far as I got before starting this thread, so further progress will have to come at a later time. Stay tuned for departure to Moho and then the tale of my recovery of all the launch vehicles I had to send up.

 

[KerballingSmasher]

One question, HOW IN THE WORLD DO YOU PRONOUNCE THAT NAME?!?

[problemecium]

Part Three: Departure

Once all the pre-departure checks were completed and then themselves checked, the small fuel tanker and space tug attached to the Phthanophaneron were detached and a course was plotted. At first I cleverly set up a maneuver node that would bring the ship to Moho at its descending node, allowing me to skip an inclination correction altogether, and executed the 18-minute burn it entailed, but upon completion I discovered that not only had Kerbin's gravitational influence over the course of the burn caused me to waste nearly a kilometer per second of delta-V and caused my trajectory to be wrong, but the planned course wouldn't have even worked in the first place. When plotting the capture maneuver, I found it would require over 6000 m/s and thus use up nearly all of the ship's remaining fuel, leaving it unable to make a return trip. I could have resigned myself to performing ISRU and thus doing a lot or repetitive trips with the mining bot and spending a very long time in orbit slowly processing all of the ore into fuel with the small refinery, but one might imagine how entirely unreasonable an idea that was. I shudder to think of calculating how many trips and how much time that would entail, let alone consider doing it. Fortunately I had quicksaved just before the departure burn, allowing me to cancel it and plot a much more convenient course:

The transfer window had not, as I had hoped, coincided with an orbital inclination node, but this wasn't unexpected. Despite the massive inclination correction maneuver of over 2000 m/s, this course nominally only consumed 6532 m/s of delta-V, leaving 3483 for the return trip, more than would be needed for either the departure burn or the capture burn and thus presumably plenty for a rendezvous with Kerbin, though I would have to be careful about inclination and have to perform some aerobraking and possibly a gravity assist using the Mun.

Thus the Phthanophaneron departed and benefited from a shorter and more efficient ejection burn, resulting in a more precise trajectory and smaller gravity losses, even though the ship was pitched up nearly sixty degrees when the maneuver was finished.

In a fortuitous turn of events, the resulting trajectory required smaller maneuvers later and thus a new projection of 3695 m/s of delta-V left after arrival, which was very satisfying. Once under way, the crew deployed the exterior solar panels, opened the payload bay to provide an enjoyable view, and settled in for the 115 days leading up to the next maneuver.

Comments:

I'm not 100% confident, but based on what experience I have with Latin names, I would say it thus:

Stay tuned for the aforementioned recovery of all the launch vehicles.

Edited July 2, 2020 by problemecium
FThanosFeyNeuron

[Misguided Kerbal]

This looks really cool @problemecium! 

[jimmymcgoochie]

On 7/1/2020 at 3:54 PM, Kerballing (Got Dunked On) said:

One question, HOW IN THE WORLD DO YOU PRONOUNCE THAT NAME?!?

Fairly simple really- just treat the "ph"s as "f"s and you should be fine. Fthanofaneron.

Google translate says that means 'checklist' 

This looks like it's going to be interesting!

[KerballingSmasher]

On 7/2/2020 at 4:22 PM, jimmymcgoochie said:

Google translate says that means 'checklist'.

That's brilliant.

[problemecium]

Part Four: Recovery

Now that the mission is complete it's time to recover the crew capsule and - wait a minute! The mission isn't complete! Ahem.
Now that the Phthanophaneron is safely on its way to Moho, the Space Program can settle down just a little and start cleaning up from the mad rush during the ship's assembly, i.e. recover the empty launch vehicles and fuel tankers.

There had actually been an incident during construction when the Space Program was down to less than 80,000 funds and unable to launch the last two drive pods, and hence the very expensive 150-ton launch vehicles had to be hastily recovered (hence my forgetting to take pictures of them). Once construction was complete, the Space Program was again rather short on funding, but thanks to managing to land all of the remaining launch vehicles vaguely near the Space Center, much of the prior expenditure was recouped. One of the two remaining 100-ton launch vehicles ended up without enough delta-V to make it all the way to a suborbital trajectory, so instead it parked itself in a 200km orbit to await recovery at a later date, while the other managed only a barely suborbital trajectory and went through multiple aerobraking passes before landing.

Next the fuel tankers were retrieved. One of the large tankers had a little extra fuel left, so the space tug and small fuel tanker docked with it and took most of the remaining fuel, leaving just enough for the tanker to deorbit itself. The two smaller ships proceeded to dock with my LKO space station and then the tanker descended for recovery. Finally the second to last 100-ton launch vehicle made it to the surface and was recovered.

As far as the Phthanophaneron itself, the mission remains nominal and the next maneuver is still a while out. During this time, however, the Space Program has the rapidly approaching Jool transfer window to address. Some crew rotations have begun and some orbiting clutter (such as extraneous relays and outmoded station modules) is being cleaned up, and Mission Control is searching for lucrative contracts to build up as much capital as possible before attempting to construct a ship to explore Jool. That, however, is a mission for another thread. Stay tuned here for the Phthanophaneron's mid-course correction and, later and more exciting, its arrival at Moho.

Edited July 4, 2020 by problemecium
dumb mistakes

[FreeThinker]

On 7/1/2020 at 12:37 PM, problemecium said:

 I set my goal at 10 km/s and a maximum acceleration of at least 0.20 gees to avoid excessively long maneuver burns.

Notice you could speed up long burns using

 

[problemecium]

Part 4.5: Recovery Addendum

Just a sort of mini-update because I finally got around to recovering the last lander and the medium-sized liquid fuel tanker I had used and forgotten to document (but which does make an appearance in Part Four docked to my LKO space station) by doing one of the most Kerbal things I've ever done. These two ships in the first image here are not docked - I'm using the fuel tanker to push the launch vehicle. I had rendezvoused my standard cleanup vessel with a klaw to do the job but it turned out to have way less delta-V than was needed to deorbit the big heavy launch vehicle, so I rendezvoused the fuel tanker instead and only after completing the rendezvous was reminded that the launch vehicle had no docking ports! Rather than try again with a third craft I decided to use the extra delta-V I had left on hand and try my luck, and it ended up being a finicky process but eventually a success.

I managed to land the launch vehicle very close to KSC, allowing me to recover it for over 95% of its full value. On the way down something in the structure of the fuel tanker caused it to make some very impressive bow waves.

Comments:

I did consider using Persistent Thrust in some form but didn't feel like setting up ModuleManager or in general having too many mods installed. Had it been harder to accomplish my goals for the mothership I would have been more motivated, but having to build a really big ship is hardly something I'm likely to complain about doing, and it didn't really even have to be that big to do what I wanted. Thanks for the suggestion though.