22 January 2013

Adventures in KSP: Going for Duna!

I've been playing Kerbal Space Program for a while now, recording my progress in this blog. Let's head for the second big milestone in my space-program: The flight to Duna...

Creating a spacecraft able to fly to Duna, land there, and get back was going to be a big step for my space program. I decided that the month-long trip would need a crew of multiple Kerbals and a crew container to house them so they wouldn't go mad in a cramped capsule. It was going to be a multi-part spacecraft to be assembled in orbit. I decided to go for a three-section approach: A central command module with the habitat, avionics and power-supplies, a thruster-section with fuel and nuclear engines, and a lander that could parachute-land on Duna and then return back to orbit with a Kerbal on board. Getting the former and the latter into a stable orbit for assembly around Kerbin was easy, getting the heavy engine-section up there was a bit harder: It took me six attempts to get the thing up there, and that only worked because I re-routed the fuel from the thruster-section to go into the starting-stages. So the whole thing ended in orbit drained of fuel. Two Kerbals came up with the habitat/command-module and one came up in the lander. The crew was on board, all I needed to do now was to actually fuel the whole thing up...
I present: The KSC Troy. Kerbonaut spacewalking for scale.

So, the Troy was assembled. I did the fueling with smallish automated fuel-transporters. After the first one reached the Troy and transferred both RCS-monopropellant, rocket-fuel and oxidizer, I realized that it would take four more fuel-flights to actually top the ship up fully. I was in for quite a bit of tedious work (which is one reason for the long delay of this post).
Delivery #whatever...
With the ship fueled up and ready to go, I raised the orbit in a test burn. Then I re-fueled it one more time, having become quite proficient at docking by this time. It was the first time I actually activated the triple nuclear thrusters and tested the thrust of the ship. It wasn't stellar but the fuel-efficiency of the ship would grant me to be able to go at 66% throttle for more than 45 minutes. It would have to suffice.
Majestic, isn't it? Sadly, that lander will not come back with it.
So the ship could work its way into a higher orbit. Upon having finished its mission, I decided I would refit the ship upon return to Kerbin orbit for further missions. For now, I fired up the Orbital Calculator and plotted a course for a transfer orbit from Kerbin to Duna.
It actually works. Even a shoddy space navigator like I can do it!
With some trial-and-error using the maneuver-planner I was able to get a course that would get me close enough to Duna to get into it's field of gravity. The problem was that I had expended almost half of my fuel doing so. Getting into a good low orbit for the lander to detach and then getting back to Kerbin and getting into another orbit there would require fuel that I didn't want to expand by slowing down. There was only one way to do so: Be daring. Aerobrake. I was going to use Duna's atmosphere to slow the ship down enough to be caught into an orbit. Now I'll admit that I quick-saved and tried this six times before I got it just right, not shooting out into space and not falling and crashing on the planet. Let's just say that the Kerbal Space Command probably had some computer-simulations ran before telling the crew of the Troy at what height the periapsis streaking along Duna should be...
Is this gonna cut it?
Now atmospheric braking with a huge spacecraft not designed to ever land can quickly become atmospheric breaking. I retracted the solar panels, as the ship was at this point still powered by the nuclear battery of the lander anyways and rushed into the atmosphere.
Aerobraking is scary.
Yeah, this was scary. The ship looked like it would totally crash on Duna, the lowest point of its course getting it as low as 6500m above sea-level. That is not very high at all.
Still scary.
The ship was turned around and violently shaking as the lander's wings created drag that made the whole thing act like a badly-designed dart of huge proportions. Luckily, the pilot in the seat was one Bureny Kerman, experienced test-pilot and daredevil extraordinaire so in the end, the ship achieved orbit. It was now time to get Neilkin, the original pilot of the lander from the crew habitat to the lander, as his was going to be the honor of landing on Duna. This required a space walk for the man whose name was close enough to that of the late Neil Armstrong to make his seat on the ship a given anyways.
Spacewalking always contains some risk. Also, notice the moon in the background.
So, the lander was manned and ready to undock and descent into the atmosphere. I would try to land it in the vicinity of the probe I had already landed as that ocean-like plain was nicely flat and low, giving the chutes time to do their thing and making sure the lander wouldn't tip over once it was on the ground. The mission-phase of the flight had begun. More in the next KSP-post!

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