The Sentar-5 Expedition (part 3- Erin) (pic heavy)

[sdj64]

You all are probably familiar with the Jool-5 Challenge. After installing Krag's Planet Factory, one look at Sentar told me it was just begging to have a similar mission. Well, not exactly begging. More like waving its fists in the air and shouting "You think you can take me!?"

NOTE that this thread will be a mission report of my attempt, it's not a challenge (but you are welcome to attempt as well if you want, or to share a similar ship that you made for this, Jool-5, or a Grand Tour).

ALSO NOTE that there are SPOILERS of Sentar and its moons, however, I will not be trying to land at any anomalies.

MISSION PLAN for this exercise in absurdity:

-modular ship assembled in Kerbin orbit.

-land and plant a flag on all 5 of Sentar's moons.

-do Science! especially surface samples.

-return the kerbals safely to Kerbin.

The basic plan is similar to Jeb's Level on the Jool-5 Challenge, but science is not a priority. I'll be lucky if they all make it back alive. Besides Planet Factory, mods used are KW Rocketry, Kerbal Engineer, and Kerbal Joint Reinforcement (my computer hates me already, I don't want to add 1000 struts to the part count).

Table of Contents:

Off to Sentar

Erin

Part 1: Assembling the Ship

In designing the ship, my main considerations are robustness and reliability, giving each module a bit more than it needs to make sure it can make it back in one piece. An additional consideration was sunlight: since Sentar is so far from the sun, solar panels will barely work at all, so all modules have to be powered by batteries or RTGs. Sentar is uncharted territory, with no one (as I've heard) ever attempting this before. I'd rather not try for minimal mass on this one. First step is to build all of the modules.

First is the drive section. With 8 nuclear engines and weighing in at almost 200 tons, this is what will get my crew to Sentar. Or more precisely, two of them. Yep, this is going to be a big ship.

Next, the lander. This universal lander will be used on all moons except Thud. It's relatively lightweight, has good delta-v, and has the small science modules on top. This one has solar panels since the design was already made before the mission began.

But wait, you ask. Doesn't Sentar's moon Ringle have the same gravity as Tylo? The lander doesn't have enough delta-V! The solution: drop tanks. The parachute ones will help with the atmospheric landings on Skelton and Erin. The lander's side docking ports allow them to be decoupled by action group.

The shuttle will help to move the landers and crew around the Sentar system, without needing to deal with moving the whole mothership.

Here is the Thud lander. With 3.14 times Kerbin's gravity and no atmosphere to slow you down, it's going to take a lot of delta-V. This lander has around 11500 of it. I should take it to Eve later, since I've never done that before.

And finally, this is the module our brave crew will be travelling in for the long journey. It also contains some science and electricity storage.

Edited April 5, 2014 by sdj64

[sdj64]

Part 1: Assembling the Ship (Continued)

In KSP, I have an irrational dislike of assembling things in orbit, if I can help it. So I put the modules on top of each other and sent them up as a stack, as they would be stacked for their journey to Sentar. This took two launches to bring up all the parts.

The lifter rocket, suitable to bring 250 tons to orbit. Each half weighs about 260 tons so a bit of the drive section's fuel was used to finish circularizing.

The first half contains the drop tanks, the habitation module, and the Thud lander.

The second half contains the lander, the shuttle, and some more drop tanks to make each half weigh the same, so it would be balanced. It also contains a new small module that wasn't in the first post: an RCS tug to assist in moving drop tanks and rearranging modules. It went into orbit on top of the lander then moved to the side where it is now.

The two modules, under probe core control, docked in orbit. The Galaxy Sentar was complete. By now I had to turn the KER Flight Engineer off, as the game crashed any time I tried to turn it on with the whole ship together.

After waiting for a transfer window to Sentar (they take a very long time to come up due to the highly inclined orbit) the brave crew for the mission was chosen. Jeb, Bill, and Bob were a natural choice, and rounding out the crew are:

Kirtrey - first Kerbal to set foot on Eeloo

Ellas and Ribley - veterans of my Jool-5 Jeb Level mission.

Luke - went with Jeb to Laythe in a spaceplane.

Hannie - relatively new recruit, went on an Apollo style moon mission.

A resupply spaceplane was dispatched to bring up the crew and to top up the Galaxy Sentar's fuel and monopropellent reserves. Sadly I forgot to screenshot the spaceplane docked to the ship. Here is a picture of the plane taking off. The docking port is on the bottom. Pilot Chris Kerman flies the plane up to dock and back to a safe landing at KSC.

[Zuni]

Looking good! Please continue your documentation.

[sdj64]

Part 2: Off to Sentar

With the crew on board and the planets in their positions, Jeb activated the nuclear engines to head to Sentar.

The burn took an in-game time of about 22 minutes, but was about twice that in real life, due to the part count. Also, it was discovered that the longer stack, with the heavy Thud lander on the end of the long but light crew section, wobbled a fair amount in transit. It prevented any physical timewarp during the burn. Should have installed KAS for their EVA struts...

Once enough fuel had been burned, the fuel in the Thud lander's tanks was transferred back to the drive section tank, which brought the wobble down.

Overall, the 2300 m/s burn used up a little over half of the fuel in the drive sections.

Two mid-course corrections were made, entirely using RCS since the ship has 6000 units of monopropellent. Together they used up about 1500 units.

Upon arriving at Sentar, the crew gazed at the breathtaking views, but soon realized there was a problem: Since Sentar was a newly discovered planet, scientists at the KSC hadn't worked out the atmospheric characteristics, and they had no idea how low to aerobrake. (Apparently Planet Factory's atmosphere info in the tracking station is wrong for Sentar). After a few "simulations" run on the ship (quicksaving and quickloading), it was determined that the correct altitude was just under 110 km.

The aerobrake was gentle, producing no flames nor high g-forces but allowing the ship to slip into a stable orbit. A plane change maneuver brought the orbital plane in line with the moons.

Once in orbit, the Kerbals took science measurements. Here, Bob examines the ship after collecting data from the goo containers, with Ringle and Erin in the background.

One other important piece of information the crew picked up is just how lightweight Sentar is. I had heard on the forums that its density is less than real life Hydrogen, but now found out how it affects gameplay. The orbital speed is very low, making maneuvers inside its SOI easy. Jeb wonders why Thud is orbiting Sentar and not the other way around.

In case you can't see it in the screenshot, that Thud transfer only costs 184 m/s.

[Commissioner Tadpole]

Wow. I guess the extremely light weight of Sentar is a 'reward' for making it into the faraway planet's orbit, huh?

[sdj64]

Yeah. Not so with the moons, though. Erin is like Laythe, Ringle is like Tylo, and Thud is... aptly named. Skelton is going retrograde on a different orbital plane than the others, and has an atmosphere as thick as Eve's but only Duna's gravity.

Up first for the moons is Erin!

[sdj64]

Part 3 - Erin

Bill and Ribley Kerman were chosen for the first moon landing leg of the mission. The shuttle detached from the Galaxy Sentar with the universal lander. It carries two large drop tanks for fuel, and two parachute drop tanks for the landing in Erin's atmosphere. The shuttle soon arrives at Erin, passing by its moon Pock.

The lander loads up with parachutes in high orbit and detaches for its landing.

The orbit was adjusted to land in the lakes region, so that samples could be collected from both the land and the ocean. As a result, the lander pierced straight down into the atmosphere, creating an impressive fireball.

The parachutes opened, and Bill floated down to a soft landing. He double-checked all of his scientific instruments, then put on his space suit and went out to plant a flag.

Bill ran down to the sea to collect a sample. This far from the sun, Erin might have oceans of liquid nitrogen or some other nasty chemicals. Nonetheless, Bill couldn't resist going for a swim.

Bill remained on the surface until dusk, then took off. The side tanks were jettisoned when they ran out of fuel.

The lander had enough fuel to boost itself back into the shuttle's high orbit. Bill transferred the scientific data to the shuttle and refilled the lander's tanks to prepare to travel to Pock, and Ribley boarded the lander.