Flieger, grüß' mir die Sonne, grüß' mir die Sterne und grüß' mir den Mond. Dein Leben, das ist ein Schweben, durch die Ferne, die keiner bewohnt! - Hans Albers, F.P.1 antwortet nicht (Adaptation in the 80s: Extrabreit)

Sunday, 14 June 2015

Kerbin Slingshot and a first Minmus landing

Loosing track, there is lots of real life including a healthy holdiday in between. So... where did I leave off here? Right, the Omniscient had done a Mun landing and was ready to hit "nav point 2", Minmus.

It takes indeed a while until I have finally plotted a course. As it turns out, every vector which is prograde to Mun´s orbit turns out "empty", i.e. no projected Minmus encounter whatsoever. It is only until try out some retrograde vectors that I realize that Minmus seems to revolve much slower around Kerbin than Mun. That, combined with the fact that Minmus is actually "behind" Mun right now, of course invalidates every attempt to reach Minums by aiming "ahead" of Mun (i.e. prograde). The right way to do it is to go "backward" on a retrograde vector, sling around Kerbin and finally find that Minmus encounter.

- Kerbin slingshot to reach Minmus, due to starting from a very crappy transfer point

This maneuver costs me about 450m/s deltaV, about double the amount I would have required if I had timed my travel with a proper transfer window from Mun to Minmus. But, with the time constraint of the upcoming Duna transfer windows, I needed to make haste. I biefly think about actually "stopping by" in a low Kerbin orbit and refuel. But this would basically mean to start an entire new travel to Minmus, and using up ~600m/s deltaV more than from my current starting point. So I execute the maneuver and hope that the Omniscient has enough deltaV left for a Minmus landing, a sun orbit and a return to Kerbin...

- on slingshot course

From here on, things seem to advance very slowly. This is only because I cannot simply warp time forward, instead I try to make "good use" of the time in between. So, what leasurly activity am I up to in the meanwhile?

One idea is to refill both the Scientia and the Scientia 2 and finally do some more landings, in order to catch some substantial science. It would feel a bit cheesy for me to just time warp foward and cash in science from my three Mobile Labs. So I design and send a first fuel ship up to the Scientia 2 around Minmus. It can either refill the former, or give the Omniscient an emergency refill in case I once more underestimated the deltaV requirements for its further ventures. The Fuel Ship is a simple, remotely steered vessel, with a fuel capacity of 2880 units and propelled by a Poodle engine. I figure that after reaching Minmus, about half the fuel can be transferred and thus almost completely fill up the Scientia 2, while still ensuring the return trip.

- Fuel Ship (in the worst possible orientation, all solar panels shadowed...)

Sending the Fuel Ship into orbit deprives it about 1/3 of its in-space fuel capacity. Of course, I could have designed it in a more expensive way so that the final stage was still 100% full. However, I did not spend all that time designing viable fuel tanker space planes in vain! And thus, my honoured utility spaceplane, the Fuel Dragon, gets once more the job to go LKO and refill the Fuel Ship before it leaves for Minmus.

In preparation to my future spaceplane launches, I place two mini-planes at the start and end of the runway. As it turned out, the EVE mod features very nice clouds, which however also occlude sometimes the runway during approach. With those two miniplanes, I basically have two nav points which are always visible and can be also used as a bearing for a proper landing approach.

 - Fuel Dragon & Fuel Ship rendez vous completed

About half an hour later, the Fuel Ship has executed its burn for Minmus, which, due to its timely launch, it will reach even before the Omniscient. In the meanwhile, planetside things start to go wrong again. I sure did launch the Fuel Dragon about a dozen times already and should be very acquainted to handle it. But, this time, attempting to land on the runway goes wrong four times in a row! Thank you, reload screen! No idea, did I get sloppy, were there some bugs in between, but it is only at the end of that game session that the Fuel Dragon finally sets down properly.

- reentry during night; the EVE mod sometimes draws a weird nightly landscape, almost a cause to de-install it again, wouldn´t it be for those nice clouds!

- approach for a landing...
(two parking mini-planes serve as bearing through the clouds)

- ... ooops!

Ok, after this episode I am again saturated with atmospheric flights. Jump to Minmus.

The Fuel Ship will arrive first and dock with the Scientia 2, with the Omniscient coming in a day later (not sure yet if it will rendez-vous, too). The Scientia 2 has 750m/s deltaV left in its tank; since the refuel is planned for a totally empty Scientia 2, I can use this up before the Fuel Ship arrives, by doing a "first ever" Minmus landing! As a target serves me one last nav point from a mission contract, which requires me to take temperature measurement on the surface, coincidentally passing right now under the Scientia 2´s orbit. Timing and killing horizontal velocity, falling down slowly.

- initiating Minmus landing procedure

All goes well, until the surface is almost reached. This is a Biome called "Slopes". Yeah, I know now why; slopes of at least 30 degrees. How the Kerbuck can I ever touch down a church tower like the Scientia 2 is??? Three tries to find a more accomodating landing spot, then my deltaV figure tells me this has to be it...

- "any landing you can walk away from is a landing"

... whew. My three amazons survived, including the ship. Don´t want to think about launching from here! I have to admit, though, landing on Minmus in principle is much more forgiving than landing on Mun. These slopes would surely have been my vessel´s doom if on Mun.

My three Kerbonauts are busy collecting scientific data, several complete stacks containing every data type, going each into a different "pods" of the Scientia 2. One set will remain on the Scientia 2 for its lab, one set will be brought back to Kerbin for quick science points, one set will be passed over to the Omniscient´s lab.

Collecting the temperature reading, my mission contract strangely does not update, until I realize that the measurement was not required on the ground, but in flight below 8400m altitude. It is already late night and I also get confused as to what science data I can collect when. There seems to be also a "low above [Biome]" point of collection, which makes my Science-Alert mod ping every time my Kerbonauts do a step, also being a jump in Minmus´s little gravity.

From now on, my sceenshots get a little scarce; which is a pity. The reason is, trying to launch the Scientia 2 from it´s precarious on-the-belly-downhill position takes all my attention, as this results in quite a number of reload-inducing explosions! After several tries to erect the ship by a Kerbonaut pushing with all the RCS power it can muster, getting annoyed that I cannot make all three Kerbonauts push at the same time, I experiment with the ship´s torque power. Rocking back and forth, the ship swings on its belly and even lifts off a little from the ground. Trying to fire the engines at the right moment (reload to find it), not too strong (reload to figure it out), not too weak (reload to... you get it!), not too long (etc), not to short (etc), I finally make the Scientia 2 lift off again. Whew. Thank reload, you can very well consider this launch a bit cheaty, but, hey, virtually every launch so far was like this; learning by doing, and all that! Taking that last temperature reading for my contract, with the last remaining deltaV, the Scientia 2 arrives back in a polar orbit (just 20m/s deltaV are left!). Phew.

Tired but somewhat content, with the resolve to eventually become a better space pilot, I log off.

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