March 07, 2014

Kassie Goes to the Mun, Part II

Welcome back ladies and gentlekerbs.  Hopefully everyone is rested after the break, as it's time for the briefing on the Kassie IV mission.  I'm Jebediah Kerman, and here with me is Lanlo Kerman, my co-pilot for this mission.


For this launch, I was in command in the habitat aboard the Kassie IV lander core, and Lanlo was above me on board the service module.

Kassie IV on the launch pad
With the massive array of engines of the Kassie IV, the flight planners and engineers wouldn't sign off on our usual approach of firing all the engines at once while simultaneously popping the explosive bolts of the launch gantry.  Instead, launch consists of starting the lander engines, letting them stabilize, then firing up the many liquid rockets of the launch boosters, and then finally igniting the solid boosters and releasing from the gantry.  

With all 169 engines at full throttle, the noise was indescribable.  In my case, because my brain simply overloaded with the sound and I lost my hearing for much of the launch, and it Lanlo's case because the overpressure wave was focused right on his capsule, and he actually lost consciousness.

Kassie IV launch

The sixteen solid rocket boosters at the corners burn for 29 seconds.  With every liquid engine on the ship sucking fuel out of those outboard tanks, they run dry less than a second later, and the four outboard tanks and their attached boosters all drop as one.  The jolt as all that thrust goes away very nearly cost me my tongue.  Approximately one minute later, and about six kilometers above the surface, the remaining 32 solid rocket boosters burn out with another massive jolt.

Kassie IV booster staging

Fortunately for our necks and tongues, the remaining launch booster stages fall off in much smaller thrust increments.  Lanlo has regained consciousness by the time we achieve an 80 kilometer circular orbit above Kerbin.  The last of the launch boosters have a few seconds of fuel left at this time.

Kassie IV in Kerbin orbit

We line up for our burn to the Mun on the next orbit, and using only the Nerva rockets, the 800 m/sec burn takes nearly six minutes.  On the plus side, the craft remains stable, and six minutes, while a lengthy burn, isn't so long that it can't be done in one efficient maneuver.  The low thrust ratio also makes it easy to dial in our trajectory nearly perfectly without a lot of fussing, and our mid-course correction burn ends up requiring a mere 7 m/sec change.

The true test of whether the Nerva rockets have the thrust we need was the arrival burn to put us in a munar orbit, the window to achieve a capture before we shoot past the Mun on an escape trajectory is rather short.  Fortunately Kassie is up to the task, and Lanlo and I are in orbit over the Mun in time for a nice dinner of reconstituted artificial roast beast.

After dinner, Lanlo undocks the service module, and I brake the lander to a complete stop above the munar midlands.

Kassie Service Module separation above the Mun

I won't claim to be the lander pilot Philmon was, he was truly one of a kind.  But I'm able to bring the Kassie down to a clean landing on the Mun.  Unlike the planned Eve landing where we'll ride down under parachutes with full tanks of fuel, for this landing on the Mun I'm using the lander's engines and discarding stages as they run dry.  By the time I land on the munar surface, I've discarded six of the lander's boosters.

Kassie IV lander on the Mun

I take a brief EVA to enjoy some acrobatics in munar gravity, and to see how the landing struts handled the landing.  My landing was pretty good, at around 2 m/sec of descent speed and 1 m/sec horizontal, and that bit of travel combined with the slope of the landing site served as a good test of the landing gear, which handled it just fine.

On the way back up the ladder into the capsule, I was able to reflect that while we hadn't installed any lights on the lander in a quest to minimize weight, the Nerva rocket was providing a slightly disquieting illumination...

The pleasant green glow of a nuclear rocket

The lander achieved munar orbit with ease as expected, it's designed for a much more difficult environment than the Mun.  Once I was in orbit, Lanlo performed the rendezvous and docking, since the service module has orbital maneuvering systems, unlike the lander.  Once we were docked, we transferred fuel to the lander, not because it was necessary, but to test systems.  Then we set course back for Kerbin.  Unfortunately, the pictures I took of the docking, EVA, return to Kerbin, and re-entry didn't come out, apparently the film was fogged by the Nerva rocket when I climbed past it on the ladder.  Lanlo was able to get this one photo out of his capsule window during re-entry using his cell phone, which he apparently brought along so he could play Flappy while waiting in orbit above the Mun.

Re-entry as viewed from the capsule

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