The Kodak Missions, part 1: Pathfinder. Purdy Pictures around Jool.

[Wayfare]

The Kodak Missions 1: Pathfinder

Why go to Jool? Why go anywhere in KSP? It's not like there's anything to really do out there. Jool really only has one thing going for it: it's so, so pretty. Hence I embarked upon the Kodak Missions. Am I showing my age?

I decided to split the program into three parts. First, an unmanned pathfinder mission will seed the system with probes, with a special focus on Laythe to scout out base locations. The second part of the program will deliver the Laythe base and any cool bits I can bolt onto the front. The third part will deliver the crew, along with additional cool bits. Cool bits being rovers and such.

This is Pathfinder 1. It consists of four probes arranged around a central structure to keep them nicely bundled. Each probe in turn splits into a satellite, a lander and a mini-rover. These probes will travel to Vall, Tylo, Bop and Pol and have a look around there. Along with snapping pretty pictures, the purpose of their mission is to determine how hard the Jool system is to get around in and how hard the various moons are to land on. The Poodle-powered bit which just undocked is the final stage of the Minshine launch vehicle, used to finalize circularization, perform orbital maneuvers, then undock from the payload and de-orbit itself. This way the Minshine launchers leave no debris in orbit.

Here is Pathfinder 2 docking onto Pathfinder 1. Pathfinder 2 includes the pusher craft and a rack of four Laythe rovers with their landing packs. These will drop onto Laythe and survey the best sites for establishing a base. A third launch docked a Rockomax X200-32 fuel tank to the back of the Pathfinder as a drop tank.

Burn baby burn! Pushing about eighty tons of craft to Jool took a lot of time. The burn was split into two parts: the first pushing it to just under the Mun's orbit, and the second bringing it all the way to a Jool encounter. Each burn took roughly six minutes. Under the stress of a 400-part monstrosity of a craft, time slowed down to about half pace. And then there were correction burns along the way... Well, you do the math.

Once I got there though, I remembered why I wanted to torture myself and go to Jool. It's the amazing vistas.

Aerobraking through Jool's atmosphere. Seven minutes of terror indeed. This was the last major maneuver of the joined Pathfinder spacecraft.

Pathfinder 1 and 2 separate on an elliptical orbit around Jool. Mission Control reported a significant improvement in feedback as soon as the two craft were more than 2,5km apart.

Moar fire! Pathfinder 2 made two aerobrake passes over Laythe, returning valuable data for the future missions. From the orbit that resulted from a 120km Jool aerocapture, a 22km aerobrake over Latyhe followed by another one at 30km yielded a decent enough orbit to finish the rest on engine power.

Meanwhile, Pathfinder 1 cruised along to a Tylo encounter that would make a nice gravity boost for the upbound probes, as well as the rendezvous for the Tylo probe. Along the way, Jool and three of its moons lined up for a nice snapshot.

Pathfinder 2 finds itself silhouetted against Jool. That's a postcard right there.

The first Laythe rover separates from Pathfinder 2. These have just enough fuel for a de-orbit burn and a bit to spare for final deceleration while under the parachute. Part of the mission for these probes was to establish landing procedures for future payloads.

The first rover, Able, descends under its chute. It was allowed to land with no engine assistance after de-orbit and correction. It set down just fine though it was a bit hairy at almost 6m/s.

Baker landed under its chute too, but engine power was used during the last 30 meters of descent. Ironically, this attempt at a softer landing cut the chute and caused the rover to set down a lot harder. Baker broke its rear-left wheel in the process but was found to be still serviceable.

Getting the descent package off the rover required a typically Kerbal maneuver: decouple the package, then drive the rover around in tight circles until it falls off! It still works even with just three operational wheels. Here, Baker observes its handiwork.

After the poor results of Baker's landing pattern, Charlie descended only under its parachute. Unfortunately its landing site was elevated above sea level by a couple of hundred meters. The chutes didn't bite the slightly thinner atmosphere there quite as well and Charlie threw a wheel. Again, the rover was still able to perform its mission.

Finally, Dog combined the lessons learned from the previous three rovers and landed under its chute, using a very gentle bit of thrust during the last 10 meters to slow it to just under 4m/s. It landed perfectly and set the standard for future landings.

Having served its purpose, Pathfinder 2 is left to circle Laythe as a testament to Kerbal over-engineering. It ended up with about 1000m/s of delta-v in excess of the mission requirements. About 750m/s of those were burned up in a course correction that really shouldn't have been necessary if the initial transit to Jool had been planned better. KSC accountants drooled at the prospect of cutting a whole launch from the mission profile. KSC Kerbonauts then beat the accountants about the head and neck with blunt objects until they agreed to allow for a 1000m/s safety margin on future pusher designs.

Next time, I'll show you how the Pathfinder 1 probes achieved their various captures and orbits around the other moons of Jool, and how their landers and rovers fared on getting down to the surface. Stay tuned!

Edited June 4, 2013 by Wayfare

[DMagic]

I like how you've packed so many landers and rovers onto such a small design. I'll be interested to see how those probes actually work out, especially on Tylo.

[Wayfare]

Cheers - there's sixteen probes in total on the Pathfinder mission: four orbital probes, four landers/position markers, and eight mini-rovers (not counting their descent packs as they are disposable). I'm anxious to see if the lander/rover combo will make it down to Tylo OK. High gravity and no atmo... Ouch.