[pecenipicek]

It was intentional, thus the name 'Debris Maker'.

In other news, my aforementioned goal of colliding things at >4km/s was a success!  Gallery

y'know, i've tried to do this. guess what happens on my end.


they go through each other. or, more precisely, they are smack dab on for collision, but, due to speeds and insufficiently fast slowing down of physics calc, they do not connect. at least 3 times i saw it in a flash appear behind the one to be collided with and nada.

[watsisname]

Yup.  Took me about ten attempts to get a collision to happen for that reason!  You can figure the odds of them colliding is roughly equal to the size of the satellites divided by the distance they travel between each frame / physics calculation.  So for example two 10m satellites with relative velocity 4500m/s and running at 30FPS, the chances of them actually hitting are only only 1 in 15. :/

[StarSlayer]

So an ASAT doesn't successfully destroy the target just makes more smaller pieces?  I guess I'll drop that proposal and stick with the tug.

[headdie]

I think it depends on how explosive the asat is

edit
if you hit the objects so their resulting velocity is below that required to orbit then they will fall into the nearest hard object and be destroyed anyway

[BlueFlames]

I think it depends on how explosive the asat is

Not necessarily.  A bigger explosion just spreads the debris out more quickly than a smaller explosion.  Yes, the debris on one side of the explosion is more likely to be dropped onto a sub-orbital trajectory, and debris on the opposite side of the explosion is more likely to be kicked up to escape velocity, but the stuff to the sides of the explosion will not have their orbit significantly modified.

What you are really looking for with ASAT is a collision.  You want to jam two things together, such that the single resultant object is traveling below orbital speed.  The more debris that is shed, the more likely you are to compound your problems by not just leaving more objects in orbit, but leaving those objects on eccentric and inclined orbits, making them harder-still to retrieve.

There is an ideal ASAT that lies somewhere between SPLOSIONS-IS-FUN and a tug, but if you have to err on one side or the other, the tug makes life a lot easier in the long-run.

[Sushi]

Yeah, I was a bit sad when after designing a lovely orbital "launch missiles at things" vehicle a while back, I discovered it was only good for turning one large object into multiple smaller objects on about the same trajectory.

A tug is the way to go for clearing space debris. These days, though, I usually just try to design/time things so that debris never makes it to stable orbit.

[Dragon]

If all else fails, you can always use a Sunbeam laser or a minigun.

[Nuke]

you should see the mess my rotating section beast made when the krackens ate it.

[newman]

These days, though, I usually just try to design/time things so that debris never makes it to stable orbit.

That's pretty much what I do, and so far I've been completely successful with that. Anything that's going to orbit has a lifter stage that almost gets it there. The upper stage then has enough fuel to do whatever it is it was sent up to do and either return home or dock with a station. Interplanetary stuff are usually self contained ships built in orbit using the same principles, so no debris is left floating around. If any interplanetary ship uses drop tanks, I tend to set a collision course with the target planet and drop them there (but this is rarely needed, I usually have enough fuel so there's little harm in just keeping the empty tanks for a bit more extra mass). I have a probe on every planet and moon (Duna and Laythe got two probes each, Duna has one additional on it's north pole and Laythe has one one on an island and an ocean probe floating near said island), a space station in orbits of all planets but Moho, one shipyard in orbit of Kerbin, one refueling station / drydock in Kerbin geo, a manned research outpost situated right beneath one of the Mun's arches, a habitat on Duna (currently manned with a 6-man crew), and an interplanetary reusable space ship (currently in orbit of Duna, having delivered the 6 man crew to the habitat base on Duna's surface). I have zero debris floating around, have never once needed to resort to use end flight to kill floating junk, and have also never needed a dedicated craft designed to deorbit junk. It's just a matter of design. I don't even actively try to design missions for zero garbage anymore - once you get used to it it's easy.

[Sushi]

I even put parachutes on my first and second-stage booster rockets, even though the game just despawns them long before they deploy. More fun to think that my design is fully reusable, even if the game doesn't care.

[newman]

Yea I've been playing with reusable designs myself. Right now most of my lifters are partially reusable - at least the upper stages are, after finishing the mission I land them back at the KSC. They're equipped with chutes, legs and small braking engines for a parachute assisted vertical landing at the KSC. Once the ship is safely down I end flight it and imagine it'll get reused I was toying with an idea of a completely reusable (no massive ascent stage that gets ditched)  jet / rocket engine / NERVA combo personnel shuttle, but we'll see how that goes. It'd need to be able to at least reach geostationary orbit and return home.

[BlueFlames]

The whole Eve station fleet is in orbit of Kerbin.  The second spacebus and interplanetary oiler are awaiting refueling, and then it will be time to look for a departure window.

Also, I realize that I should have put everything for this mission in a retrograde orbit of Kerbin, since the fleet will be dropping their interplanetary orbit closer to the sun, but.....oops.  The fact that I'm effectively bringing a mobile fuel depot along for this mission means that I can probably afford some inefficiency along the way.

[watsisname]

Also, I realize that I should have put everything for this mission in a retrograde orbit of Kerbin, since the fleet will be dropping their interplanetary orbit closer to the sun, but.....oops.  The fact that I'm effectively bringing a mobile fuel depot along for this mission means that I can probably afford some inefficiency along the way.

Actually, the direction you orbit Kerbin doesn't matter for where you want to go in the solar system, and it's better to do everything prograde anyway since that takes advantage of the little extra orbital velocity you get from Kerbin's rotation.  To go to the inner solar system, do your escape burn when you're in front of Kerbin's direction of motion about the sun, which for a prograde orbit is roughly when the sun is rising over the horizon.

[BlueFlames]

Final refueling operations are underway, and whilst the little oilers were racing about, I took a few screenshots of the fleet:

Interplanetary Oiler #1


Interplanetary Spacebus #1


Eve Station Power Module


Interplanetary Spacebus #2


Interplanetary Oiler #2


Eve Station Hub


Some design notes:

• The eagle-eyed will note that the first interplanetary oiler is lacking some struts that are present on the second.  That's because I stupidly undocked the command module and redocked it shortly after.  Problem is, undocking disconnects struts, and redocking does not reconnect them.  The command module is fairly small, so I'm not too concerned about it getting twisted off in later maneuvers, but we'll see.

• The spacebusses use an inline docking port, rather than the usual shielded, nose-mounted port, because I couldn't make the lander work without the drogue chute on the nose.  Without it, during landing tests, the radial chutes would deploy, stopping the command pod, while the habitation module would just keep on going.  The drogue chute made the whole process gentle enough to not rip the whole vehicle apart.

• Nothing too special about the power module, except that I went with quad-ion-drives for its final propulsion stage.  What else was I going to do with all of those solar arrays and 2000 units of battery capacity?  I could have actually supported more ion drives with that solar array, but only if the thing was facing directly at the sun, not to mention the structure holding the engines would have gotten prohibitively long or blocked the inner solar panels.

• On the station hub, it's difficult to see, but there is a tiny decoupler, positioned between the two ion drives, which will jettison the NERVA and fuel tank.  Ultimately, this will be necessary, because once their command pods are removed, there's nothing left to guide the oiler payloads in to dock with the hub, so the hub will have to dock with them.  Having a rocket dangling off the back would be less-than-ideal, during a sideways docking maneuver.

• I've thought about pre-assembing the station in Kerbin orbit, and sending the whole thing to Eve in one go, instead of trying to juggle a fleet of station components and return vehicles.  There's two reasons I won't go that route.  First, the docking nodes are made of jelly, and I don't trust them to hold together while such a beast of a vessel tries to maneuver.  More importantly, can you imagine trying to turn such a huge vehicle?  There's not enough RCS fuel in the world, even taking into account that I'm still playing 0.18.1, with the super-cheaty RCS.

And some preliminary notes on the flight plan:

• The outer fuel tanks of the spacebusses all have LV-909's attached.  I'll probably deactivate them all to save on fuel, relying entirely on the NERVA for maneuver burns, at least on the way out.  That probably won't be necessary, but the only transit test this thing has undergone was when a lighter version made a trip out to Duna, so I want to play it safe with these, on the trip to Eve, since everyone is relying on these craft being able to return to Kerbin.

• Some of the ships, the station hub, in particular, and the power module to a lesser degree, have very little liquid fuel for the journey.  To maximize my fuel margins, I'm planning on splitting the ejection burn for each ship up into three burns, one to get to 3,000-5,000km above Kerbin, the next to get to 20,000-30,000km above Kerbin, and the last to get out of Kerbin's SOI and set up a rough encounter with Eve.  On the final pass, all manned vessels shall deploy someone to apply their "Hermann Oberth is my copilot" bumper stickers.

• I'm not 100% sure what to do with the interplanetary oilers' command pods, prior to the crews abandoning them.  I feel like one of them has to become a Gilly lander, if only to spite that little bastard of a moon for eating my only successful interplanetary mission in 0.17.  The problem with that is that I have to have one of the spacebusses waste fuel going out to Gilly to pick up the crew out there, instead of near Eve, and the Kerbonaut(s) who land the pod will have to EVA into orbit to meet the bus.  Now, it's Gilly, so EVA-to-orbit is certainly possible, but I've certainly never done it before.

• Aside from that, the efficiency-kick should ensure that the spacebusses have plenty of fuel for a straightforward return trip (expeditions to Gilly notwithstanding), and everything else is meant to stay in orbit of Eve.

[BlueFlames]

The fleet has escaped the bonds of Kerbin's gravity and is on its way to Eve.  Juggling ships was managable, though there were a couple of places where I faced some time pressure to finish one ship's maneuver, so that I could switch to another and start its maneuver, before missing its window.  Because of that time pressure, I did wind up using the LV-909's on the spacebusses.

That fuel expenditure won't be the fleet's primary problem.  I barely used up the first set of drop-tanks on the spacebusses.  The problem is that the Sepratrons on those drop-tanks were not aimed well for peeling the spent tanks away from the ship.  In fact, they tend to smash the spent tanks into the center fuel tank.....except when they're smashing the spent tanks into the NERVA.  So, now one of the vessels that needs to make the full, round-trip is stuck with engines of half the specific impulse of the main engine.

Fortunately, I didn't just mindlessly mash the time compression key, as soon as everything escaped Kerbin orbit.  I sent up a third spacebus, an in-game day after the fleet left to serve as a contingency, should the damaged one be unable to make the return voyage.  The third spacebus was quickly modified, before launch, removing the Sepratrons, and I shuffled the Sepratrons around in the staging for the spacebusses already underway, so that they will not fire.  No sense compounding the problem.

That aside, splitting the escape burn into multiple burns worked quite well.  It has helped stretch fuel supplies a little further.  My first burn shouldn't have aimed for quite so high an apoapsis, but that's a mental note for future interplanetary missions.  The unmanned vehicles have loads of fuel left, compared to what I had been expecting.

So, besides nearly crippling one of the only ways that several Kerbonauts have to get home, the mission's going quite well!

[newman]

What exactly is your goal on Eve? Orbit? One-way trip? Return trip from Gilly? Or the ultimate cluster**** of a mission, manned return mission to Eve surface?

[BlueFlames]

Ultimately, I'm going to do a manned landing-on-and-return-from Eve.  This fleet is going out, in advance of the landing mission, to set up a refueling station, which will ultimately reduce the size of the lander that will be going to Eve.  After the station, I will probably send some unmanned landers, so that I can get a feel for the mechanics of taking off from Eve.  Sooner or later, though, I will get three shmucks Kerbonauts to the surface of Eve and bring them back to Kerbin.

[newman]

That's very ambitious, good luck! As for a manned return mission, just a heads-up; it's currently the toughest challenge in KSP. Eve has about 170% Kerbin-equivalent gravity, but that's the good news - the bad news is that the super-dense soup it has for atmo will produce increased drag, and a rocket that can just get to Kerbin's orbit won't make it to 20km altitude on Eve due to this. Basically, you need to safely land a rather large rocket with full tanks to have a chance of making it back to orbit. Safely landing massive stuff with chutes only so it doesn't all break apart when the main chutes deploy presents a challenge in itself. There have been proposals to use wing surfaces on the lander and utilize the thick atmo to provide lift during ascent - this would require a non-vertical ascent, more like 45 degrees or so. In theory, the lift should help reduce the amount of delta-v needed, but I haven't tried this and have no idea if it would work.

[BlueFlames]

As for a manned return mission, just a heads-up; it's currently the toughest challenge in KSP.

That's why I'm doing it.  If I can land on and return from Eve, then I can pretty well land on and return from anything.

[Dragon]

I'm currently trying to develop an SSTO rocket which would launch from Kerbin, refuel in orbit, then fly to Eve, refuel there, land, launch again, refuel once again and land on Kerbin. I'm actually getting nice results, but lag and wobble make this sort of stuff very difficult.