The Emerald Star: A mission to Jool's moons

[Robin Patenall]

Rainbow’s bright idea
It looks like while I was moving the Emerald Star, Rainbow Dash has been thinking, and while normally that’s cause for concern, it looks like her scare with the aerocapture has made her re-evaluate a bit. It seems that she might have designed a sensible mission expansion that we can do with resources that would only be wasted and is actually well thought out.

She noticed that the remaining fuel and oxidizer left in the SSTO’s long range tanks, which at this point is going to be wasted in Laythe low polar orbit, is almost enough to refill the SSTO back to the design levels. There are only about 180 units of liquid fuel missing and the SSTO, designed for Kerbin, tends to have some left over after landing and returning to Laythe orbit, so long as the pilot doesn’t fly around too much. So her idea was that, given some constraints, she might be able to land the SSTO, take off, rendezvous with the long range tanks, refuel and then go on to perform the primary mission.

The two biggest constraints were that:

• She needed a landing point where she could safely brake to a stop without using the emergency arrest parachutes as she would not be able to repack them. This means nice and flat.
• She wouldn’t be able to fly around too much as she needs to conserve fuel. So the landing point needs to be a big target.

Turns out that Rainbow Dash noticed that the Laythe polar ice caps are, like home, as flat as a pancake. A perfect landing spot. She even selected the South pole as it would mean that the sun would be behind her, instead of in her eyes, and that her overrun, if landing in sunlight, is more polar icecap, not the ocean. All pluses.

I’ve set up some simulated missions based on this using the SSTO’s cockpit flight computer and if she can complete them, without stranding herself, I’ll give her provisional approval to raise the idea with Twilight (who is the mission specialise for Laythe and will have the final say)

Note: Rainbow jumped on the sim and on her first attempt managed to re-dock with the tanks, refuel the SSTO and leave the tanks with about 700m/s of dV (when not playing tug to the SSTO) so they can raise their orbit to over 1000km and act as an additional relay. It looks like a go…
 

[Robin Patenall]

Laythe Landing 1
After a half dozen simulated runs at the south pole, where nobody died, I gave Rainbow the okay to ask Twilight if she’d like to add a stop to the mission to get some more scientific information.

Obviously, she said yes.

So Rainbow undocked from the long range tanks and brought up the flight controls and plotted an atmospheric entry that would put the SSTO down at a latitude of -87 degrees, close to the pole. She also brought up the science controls for Twilight so she could make measurements as they passed through the lower atmosphere.

A retrograde burn pushed the SSTO into the atmosphere where it started to aerobraking.

Rainbow was right about how smooth the polar regions are, so the touchdown and coming to a halt were anticlimactic.

They planted a flag, and took some public relations photos of them in the land of Perpetual Twilight.

Once Perpetual Twilight had exhausted all the experiments she could do and safely stored the results, she and Rainbow got back on board and waited for the long range fuel tanks to pass overhead, so she could take off. As Laythe had rotated, the orbit of the fuel tanks had shifted relative to the ground. If the SSTO had been near the equator it would have taken half a Laythe day (7h 20m ish) for the orbit to be close but near the poles it was just a slight change in heading.

Once in a stable orbit, Rainbow plotted a rendezvous with the long range tanks. When she finally docked, Rainbow Dash refilled all the tanks on the SSTO to design limits and it looks like there are 400 units of LFO remaining in the long range tanks (with about 60 units of extra fuel). When undocked from the SSTO this will give the tanks about 1000m/s of dV which will be used to push them into a higher orbit where they can act as a communication satellite.

[Robin Patenall]

Science Satellite Retrieval
While Rainbow Dash and Twilight were playing Antarctic explorers, we decided to pick up the science satellite that we sent through Jool’s upper atmosphere. It was in nearly the same orbit as the Emerald Star, but it still needed over 300m/s of dV as we needed to change the argument of periapsis

A bit of orbital work and the satellite was docked to the Emerald Star and it’s precious data and atmospheric samples from Jool safely stored.

Breaking News!
While we’ve been orbiting Laythe, we’ve also been scanning the ground and our sensors have detected some sort of anomaly. It’s even on the equator, so it’s a perfect target for Rainbow Dash and Twilight to land at. In other news, it seems that the user interface for Kerbnet was written by griffons; I’ll submit a bug report that the anomaly icon needs to be bigger so people without eagle eyes can actually see it. 

[Robin Patenall]

Laythe Landing 2 (and 3)
The first thing that Rainbow and Twilight had to do was wait for almost a Laythe day to bring the anomaly under their orbit. Technically, this would happen after half a day, but that would mean that Rainbow would be landing in unknown terrain at night. Even she had enough sense not to do that if she didn’t have to. 

Unfortunately, Rainbow’s sense had run out and the aerocapture scare had been somewhat forgotten, so she decided to be helpful. Apparently, she saw a shallow inlet with gently sloped shores that was more or less, directly in her flight path, so she decided to give Twilight the chance to collect more data by landing the SSTO just off shore.  

I somewhat blame myself for this as we had told Rainbow that the SSTO was buoyant and that the engines would give her some thrust and manoeuvrability in the water and that in the event of a critical failure, shallow water might be the safest place to touch down if the land was problematic.
We did not expect her to do it intentionally.

After Twilight collected all the readings and samples she could before succumbing to sea-sickness, Rainbow successfully navigated the SSTO through the gaps in the sea ice and drove it up onto the shore.

After Twilight’s dose of Dramamine had taken effect, she did another round of science tests, this time while they were landed on the shores rather than floating on the water above them. Once done, Rainbow took off again and flew the short distance to the anomaly that we had spotted from orbit.

As the terrain by the anomaly was quite hilly and undulating, Rainbow overshot the target location a little so that she could land on a relatively smooth area, but even then she had to deploy the landing arrest parachutes. To save them from walking (the designers of our EVA suits were miracle workers but even they drew the line at wing sleeves, and Twilight had been told that teleporting was limited to a last resort measure), Rainbow taxied the SSTO back to where she had spotted the anomaly.

I’m beginning to think that some higher power is messing with us. The skellington I’ll believe (especially after Fluttershy’s deep space kraken), but the potted plant? Twilight was happy though, I think that she might have been irritated if everybody but her had found something strange and interesting on the trip. (And now that I think about it, she took a cutting from the plant and brought it back with her… Let me check that she isn’t feeding it blood or anything)

Take off and return to an equatorial orbit was no problem, between Laythe’s atmosphere and the SSTO’s powerful engines Rainbow managed to get the apoapsis into space with just the airbreathing jets. Matching the Emerald Star’s orbital plane and circularising left them with a significant amount of deltaV.

Rendezvousing with the Emerald Star was a bit of a compromise. We lowered the Star’s apoapsis to 440km and did the final manoeuvres with the SSTO. This left the Emerald Star in a better orbit for final departure but didn’t use as much fuel as moving to a fully circular orbit would take.

Apparently Twilight was prudent enough to not start shouting at Rainbow about her stunt with the water landing until they had left Laythe and docked. I eventually had to send them to separate corners. Rainbow is sulking in one of the emergency return pods and, given that we don’t have a library, Twilight is checking off lists in the lab.
 

[Robin Patenall]

Pol Landing
About the time that Twilight started talking to Rainbow again, Rarity and Fluttershy arrived at Pol and put the lander and drive core into a polar orbit, allowing them to perform a full high survey.

As the high orbital survey was concluding, the scanner picked up something strange. As no other place had been found that looked especially interesting, Rarity decided to make the, cheap, plane change to place the anomaly under the landers path while lowering the lander’s orbit for a low survey

Once the low orbital survey was complete and the location of the anomaly was better identified, the lander was undocked and a descent was plotted that would put them reasonably close

During the descent, Rarity couldn’t see anything unusual (unusual for Pol anyway) and she decided to prioritise a safe landing on the flat area in front of the large mountain over searching for the anomaly.

[Robin Patenall]

Pol Anomaly and Science

Apparently, it’s not just Griffins that have eagle eyes. While helping Rarity with running the Pol science experiments, Fluttershy spotted the anomaly halfway up the mountain. If you have good eyes, you might be able to see it just above the top of Rarity’s helmet.

Given the low gravity of Pol, it was at least conceivable that Rarity might be able to put the lander down on the side of the mountain but it wasn’t all that far, so Rarity hooked up the extra EVA fuel tanks to her EVA pack and just flew over there.

When she arrived, she looked for a good landing point just up from the anomaly and found a very interesting rock sticking out from the ground that she could alight on.

Well, Rarity found the anomaly, Rarity documented the anomaly, Rarity took samples from the anomaly and Rarity decided to otherwise ignore that the anomaly existed. Something I agree with.

Once Rarity returned from the thing that she was pretending didn’t exist, she and Fluttershy took off and biome hopped to the nearby highlands and lowlands to check them out and then a longer hop to the north pole.

Once they completed all the science on Pol, they took off and rendezvous with the drive core.

Returning from Pol

It turns out that both of our pilots are crazy.

Once Rarity and Fluttershy had re-docked the lander to the drive core, they planned a reduced deltaV plan to arrive at Laythe using a gravity assist at Tylo to lose energy.

Once they arrived at Laythe, Rarity did a burn at periapsis to capture into an elliptical orbit.

It was at this point that Rarity showed her inner Rainbow Dash and decided to save some more detlaV by aerobraking using Laythe’s atmosphere. Now, she did this very carefully, taking many shallow passes and nothing showed anything other than slight temperature warnings. Admitally, I’d have preferred that the infrared telescope didn’t hang out in a plasma stream for a few minutes every hour or so for a couple of days, but it wasn’t needed anymore and it wasn’t damaged in any way. 

Eventually Rarity reduced the orbital apoapsis down to match the Emerald Star’s orbit and then raised the periapsis to rendezvous with it.

The docking was rather tight and I’m glad that Rarity was piloting rather than Rainbow Dash. Rainbow would have managed the docking but I don’t know how long I would have had to be out on EVA touching up the paintwork. Even with Rarity in control, it was a tight squeeze.

[Robin Patenall]

Squeezing out more Science
Now that all the parts of the planned mission are complete and everypony is in one place, it is time to take stock of what resources we need to get home and what resources we have in addition to that.

The first step was to reconfigure the Emerald Star for the return trip. The least obvious change was that the habitation module has been rotated to make ‘forward’ towards the drive truss, this allowed us to take the full drive core and move it into a position to push the habitation module home. All the LFO tanks on the emergency return capsules were topped off as were the LF tanks in the drive core.

Some quick calculations show that we have plenty of fuel to get home, in fact we have just a shade under 8.6km/s. We could probably get home with half that amount and not be overly concerned.

The remaining fuel comes to 5300 units of liquid fuel, 1423 of oxidizer and 1300 units of monoprop. This comes to enough to fuel the SSTO to design limits, the lander to about 2/3rds full and have enough liquid fuel in the last drive core to give it 2.5km/s of deltaV.

I did do a bit more engineering work. I moved the telescope back to the science satellite and took the RCS thrusters that I originally took off the SSTO’s long range tanks and fitted them to the back of the drive core we’ve been using to ferry the lander about. We have massive amounts of monoprop on the drive truss, which we will be leaving here at Jool, and the drive core usually uses LFO for RCS which we have a limited amount remaining. Switching to monoprop (assuming the engineering module with its tanks is left attached) will allow more use out of it.

We do need to decide if we use any of the resources we have left for more science. My thoughts were:

• Pol and Bop were studied pretty much completely by Rarity and Fluttryshy.
• Tylo is right out, we might be able to land but we’d never take off again and doing anything off equatorial, even in space, is probably beyond us.
• The SSTO can visit Laythe again but anything too inclined may be a problem and there isn’t much left on the equator unless we want to see if Rainbow Dash can launch from the ocean.
• We might be able (pulling some LFO from the return capsules) to return to Vall and land somewhere on the equator (specifically not he Vall henge site)

So I’m off to see what Twilight thinks.

Addendum
Looks like Twilight had another idea. Use the current lander configuration and launch it toward retrograde to allow her to collect science from the space near Jool, that seems reasonable and doable, and she wants the periapsis to be low enough to scrape Jool’s atmosphere. That needs thinking about.
 

[Robin Patenall]

Science near Jool
Having discussed it with Twilight, I okayed the mission to near Jool space with the restriction that nopony is to be on untethered EVA below 500km altitude, everypony must be in the engineering module or strapped into a command seat. This means no resetting of science experiments.
Once given the go ahead, Twilight spared no time in grabbing Rainbow (apparently the great water landing debacle had been forgiven), getting in the lander and undocking.

Rainbow plotted an ejection that would take them down and just scrap Jool’s upper atmosphere. Once done she’ll raise the periapsis slightly and wait a few orbits until they intersect Laythe again.

Once they reached near Jool space, Twilight ran all the science experiments while Rainbow did crew reports. After they had finished, they were nearing the altitude at which Jool’s upper atmosphere starts so Twilight got strapped in and set up the experiments to run.

After the lander’s altitude passed 500km, Twilight unstrapped herself and moved to the engineering module to pass a few days until they intersected Laythe’s SOI and Rainbow could show off by repeating Rarity’s aerobraking manoeuvre and redocking with the Emerald Star.

[Robin Patenall]

Science on Crater Island
With the total amount of fuel we have left over, I gave Twilight the option of a second extra science mission.

I noticed that, on Laythe, there is a crater with an island in the centre that Twilight had highlighted as having two interesting biomes, the bay itself and the island. It’s about 15 degrees above Laythe’s equator, which is beyond the SSTO’s ability to adjust its inclination. It might be able to reach it going down using its ability to fly but there wouldn’t really be enough deltaV once it returned to orbit to guarantee that it could match inclination with the Emerald Star and rendezvous again.

The solution I had was to undock the drive core and engineering module and have me fit a docking port that was compatible with the SSTO to the front. 

It wasn’t pretty but it allow the drive core to do the inclination change for the SSTO (about 400m/s) to allow its orbit to pass over crater Island and, once Twilight and Rainbow Dash landed, undo the inclination change and rendezvous with the Emerald Star.

Once the inclination change was made a descent was plotted that would bring the SSTO down at its most northerly point and our intrepid team needed to wait a few orbits for the island to reach the target point near local dawn.

The descent went fine and Twilight was able to run some of the science experiments while flying over the bay. Rainbow had learnt her lesson about unexpected landings and managed to make a short touchdown on the shores of the island 

Twilight ran her last set of science experiments quickly so that Rainbow Dash could take off again before they drifted too far from the orbital plane of the drive core.

Once in orbit, Rainbow rendezvoused with the drive core.

Now docked, they used the drive core to match inclination with the Emerald Star, rendezvous and dock.

[Robin Patenall]

Going Home (Jool)

So, we’ve left.

Technically, we could have dropped the SSTO to Laythe again, but unless I wanted to test if Rainbow Dash can manage a water take off (I don’t) there isn’t anywhere to land that would have been interesting.

For a minimum deltaV return, we could have waited for a launch window to Kerbin, but as we had so much fuel we used a slightly more expensive “launch now” plan.

One thing I did do was to fit the Clamp-o-Tron docking port to the node of the drive truss we undocked the habitation module from. This was to allow us to move the SSTO there and better balance around the thrust vector generated by the drive core that we are leaving behind. 

The manoeuvre plan is to eject from Jool retrograde, lowering our periapsis with respect to the sun until it meets Kerbin’s orbit. A burn there will set us up for a Kerbin rendezvous and lower the velocity that we will have to capture at. Note, that we are splitting the ejection burn and the 264m/s burn we had queued up is just the initial kick.

We waited to get into position and burned, first to raise out Laythe apoapsis and then to eject from the Jool system

Tylo was in a position to give us a slight helping hoof as we left.

What was left behind

Before we left Jool, we used the relay satellites to remote control the SSTO, undocking it from the ventral docking node and moving it to the new forward node.

The drive truss, the SSTO, the lander and the engineering module were all pushed into a much neater 250km circular orbit by the drive core using some of its remaining fuel. This will make it easier if future missions want to make use of it.

[Robin Patenall]

Going Home (Travelling)
1 year, 368 days after departing Laythe

Once we left Jool’s sphere of influence, the pilots and I went into hibernation for the journey home. The science nerds Bon Bon, Fluttershy and the Science Nerd stayed awake so that they could begin processing the extra results and samples in the lab. 

At the moment Rainbow Dash and Rarity are still asleep, but I’m up to make an inclination change to make the Emerald Star’s orbital plane match Kerbin’s. I’m not sure that Twilight actually noticed that I’ve been hibernating as all I got was a “Morning Pinkie” when she saw me.

I’ve got some maintenance to do  before I re-enter hibernation for about 150 days when we need to for the major deceleration burn.

2 years, 98 days after departing Laythe

Big burn time, we knocked off  just under 1500m/s and brought our apoapsis down to just outside Duna’s orbit. This is easier to do in deep space as our TWR is still quite low and reducing out velocity now will make it easier to capture at Kerbin once we loop around

Back to hibernation for another year and a half.

3 years, 378 days after departing Laythe

We’re home.

After almost four years after leaving Laythe, we are back. We did an initial capture burn at Kerbin periapsis and brought our apoapsis to within the Mun’s orbit. Then performed a few burns to bring us into a circular 100km orbit.

[Robin Patenall]

Going Home (Landing)
Being back in LKO after eleven and a half years is an amazing experience. Seeing Jool’s moons up close was wonderful, but being home is something special.

We could land with the emergency return capsules, they are good enough that we could probably bullseye the KSC, but we’d have to dump all the fuel onboard (they were designed that we could perform a breaking burn and safely re-enter Kerbin’s atmosphere from the Jool-Kerbin transfer orbit). It would be very wasteful, so the KSC is sending up a remote piloted passenger SSTO to pick us up.

A quick flight and a boost put the space plane in a 76km orbit.

The space plane was rendezvoused with what’s left of the Emerald Star. We didn’t have a compatible docking port, so the SSTO was just parked nearby and our crew went on EVA to board it. During this, Twilight very carefully transferred the two boxes of samples and experimental results to the space plane.

If we send people back up (and Twilight said “We’d better, I’d barely started analysing the third set of data in the lab”) we’ll have to send up a docking port that will match the one on the space plane, or possibly a new segment and use the Emerald Star’s habitation module as the core of a space station.

A push back using RCS and a quick retrograde burn sent us back into Kerbin’s atmosphere.

A few minutes later, we touched down and we were home.

[Robin Patenall]

Epilogue 
So there we are, with our hooves back on Kerbin (metaphorically, we have a metre and a bit to go once they wheel a set of stairs across to us). We’ll be spending some quality time in quarantine to recover from our trip and build back our immune systems. Twilight managed to not run off when the technicians from the research and development department unloaded the samples and experimental results. She was making puppy dog eyes in their direction (the samples, not the techs) and will probably be burning up the communication channels between medical and R&D as soon as the doctors stop prodding her.

We did get one piece of new. The technicians did a quick inventory of the science  that we returned and came up with a total of 61174.6

[damerell]

So, ah - why no Applejack?

[Robin Patenall]

5 hours ago, damerell said:

So, ah - why no Applejack?

Somewhat annoyingly (but I understand the reason why), the mod hard-codes the profession for each named character and Applejack is an engineer. It's not even the obvious Unicorn = Scientist, Pegasi = Pilot, Earth pony = Engineer mapping and I spent hours trying to why Fluttershy didn't want to be a pilot and The Great and Powerful Trixie wasn't a scientist.

Alas, I needed 3 scientists, 2 pilots and an engineer so I'd have 5 mission specialists in the of pilot / scientist combinations and more than 6 crew would have necessitated a different set of emergency return pods in the event that I didn't have the fuel to capture and circularise when they returned to Kerbin.