So close and yet so far

[Commander Zoom]

I've been busy with other things and other games of late, so last night was my first "eh, what the hell" attempt at an interplanetary mission. I added a few fuel tanks to my "Rover X" rocket, which has proven quite capable of putting a mini-rover on both moons of Kerbin, and swapped out the upper stage engine for a NERVA. (And then, after a little more testing, stuck lander engines on the extra tanks for a little more kick before firing up the NERVA for transfer.)

My first hint of trouble was when I realized my phase angle was all wrong for transfer to Duna. Like, almost 100 degrees wrong. Well, I'm already in orbit, so there's nothing to do but turn up time acceleration as far as possible and wait... and wait... until my launch window finally opened. And then wait a little more, for my optimum ejection angle. But after something like 5-10 real-time minutes, I was finally on my way!

Planets, it turns out, are surprisingly small and hard to hit from a distance. My overhead plot showed my first attempt was going to be an overshoot, so I dialed it back until I got a nice "capture" icon. Well, not "capture" precisely, as I knew from munar landings that I'd have to brake into orbit. And then I actually got out there, with Duna and Ike catching up from astern, and discovered that I was "low". Really should have zoomed in and checked that predicted path earlier. But okay, we're here now, let's see what I can do.

I actually managed to brake into a highly-inclined, nearly-closed hyperbola around Duna before I ran out of fuel. Well, damn. Almost. But wait! I've got a pair of propane tanks and small thrusters on the rover itself. Let's fire those up... okay, ditch the heavy, useless NERVA and empty tanks, then fire those up, and see if we can at least close the orbit. Okay! Can we circularize it? Yes! So now I've got a rover whipping around Duna at about 30km up, and am wondering if I can actually land this thing.

[i'll post some pictures here later, when I get home.]

Almost. I almost did it. Maybe if I wasn't coming in so fast and shallow, or if I'd kept holding down the button after killing my horizontal velocity, or started the braking burn just a few seconds earlier; I honestly believe it was as close as that. Or if I had remembered I had a quicksave before I despondently closed down the program. But I didn't, and I didn't, and so that rover slammed into the rust-red crater at somewhere between 40 and 20 meters per second. BAM.

Maybe next time.

[John Bedlam]

Duna has an atmosphere just barely thick enough for aerobreaking, you could have spent a lot less fuel on slowing down if you'd gotten your periapse to about 12 kilometers high. Good first try though.

[RoboRay]

If you set your PE for 10 or 11km as you approach Duna, you won't have to burn much fuel at all to get into orbit. Aerobraking through the atmosphere will capture you into an elliptical orbit. From there, just a a little bit of fuel will let you raise peridun up out of the atmosphere if you wish to remain in orbit, or you can pick a landing point and set right down immediately.

[The Destroyer]

Try parachutes. they work wonders. also, did you deploy your gear? on kerbin i had to abort a rover and it came down to the ground at 42 m/s (gear down) and survived.

[Commander Zoom]

Well, the problem (the main one, at least) with my transfer orbit is that I eyeballed it from the system-scale map and didn't zoom in to check the details until I was too close and (almost) too late. I had to use all the fuel I had left in my NERVA stage just to convert my wide-and-low flyby into a closer pass. Once I switched over to the rover for final orbit and/or landing, I had "enough" fuel; I just left it a little too late to do my final burn, and couldn't kill all of my velocity with the time, altitude, and thrust I (didn't) have.

EDIT: Yeah, I saw the chutes on Pathfinder and was planning to steal copy that idea. Didn't make it into this revision. And no, I didn't drop my gear; probably should have. In my experience, the rover doesn't fly very well with the wheels out.

Edited September 27, 2012 by Commander Zoom