Visiting Gilly, help?

[ohlookabirdie]

So i am planning a mission to land a few dudes on Gilly and return home.

so far i've only been able to manage a few fly-bys, so im looking for tips on making orbit, best orbit hight for landing and stuff like that.

and anyone show me what they have landed on gilly?

Thanks

[celem]

Gilly has feeble gravity and is one of the easiest landings around.

Some thoughts:

Gilly has a pretty eccentric orbit round Eve, I have most luck getting into a high-eve parking orbit that brushes Gilly's closest approach, then timewarp to wait for the alignment, chasing the moon generally leads to wasted dV for me.

You dont want high relative velocity when encountering it, due to the feeble G it will take a lot of fuel to capture, try and get an encounter that synchs speed (easier if using the above tactic to intercept)

I get into low-gilly parking, round 10km, just beware of some of the mountains and check your blue orbital path on the map to ensure its not clipping the terrain somewhere.

It takes very very little to kill horizontal velocity, you wont even be making 100ms so the deorbit burn is cheap as chips. If you kill horizontal V too early you will have a very long float down, much of it below 8km and limited to 1x. You may need to force timewarp with 'alt-.' Its more efficient to come in very shallow, as you never reach scary speeds here and late-braking at low-altitude is completely unstressfull as you drift aimlessly downwards

You dont even need legs for gilly, landing on an engine is fairly simple as getting a landing speed below 1ms is feasible.

I dont have a screenie on this machine, but my last lander was a pancake tank with a poodle on it, couple of little radial tanks without engines (with decouplers and fuel-lines) were including purely out of habit, i usually ditch these on ascent from a world to lighten for the return to kerbin, but escape from gilly surface back into eve soi is like 130 dV and I didnt need to drop those radial backup tanks until i was actually back in kerbin soi.

All in all its a fun landing. From entering it's soi to leaving it again shouldnt really cost you more than a couple of hundred dv tops

Edited November 14, 2013 by celem

[Superfluous J]

I have no images, but I did do run to Gilly when I heard it was really easy. You really don't need much, especially if you aerobrake at Eve. Check out this needlessly complex aerobraking calculator for more.

If you want to see the master at work, check out Scott Manley going to not just Gilly but Minmus (and then returning to Kerbin and landing!) with a 5-part rocket.

[ohlookabirdie]

thanks guys, my problem has been the capture. i seem to be hitting it to fast

[Febin]

If you really need to, the Kerbals 600m/s jetpack can land you on Gilly from orbit, and take you back up easily. It works greatt, gives you the EVA and surface report, no instruments though. Good luck!

[Crush]

While it is possible to perform an EVA landing on Gilly and get back to the ship in orbit, that's nothing a beginner should attempt. It requires a lot of experience with orbital rendevouz to maneuver a Kerbal to a capsule in orbit. You can't use maneuver nodes on EVA and can't use the jetpack while in map view, so you will have to orientate yourself by surface, stars and sun and use your own judgement to estimate when to thrust how long into which direction.

Still, it's one of the most interesting challenges in KSP.

Edited November 14, 2013 by Crush

[Sirrobert]

While it is possible to perform an EVA landing on Gilly and get back to the ship in orbit, that's nothing a beginner should attempt. It requires a lot of experience with orbital rendevouz to maneuver a Kerbal to a capsule in orbit. You can't use maneuver nodes on EVA and can't use the jetpack while in map view, so you will have to orientate yourself by surface, stars and sun and use your own judgement to estimate when to thrust how long into which direction.

Still, it's one of the most interesting challenges in KSP.

I think you can use the jetpack on map mode, though you can't change direction

Scott Manley did it (who else)

by spacewalking from Gilly to Kerbin

[Moar Boosters]

thanks guys, my problem has been the capture. i seem to be hitting it to fast

When planning your intercept, make sure your orbit doesn't doesn't go past Gilly's orbit. You need to get the intercept right at the apoapsis of your Eve orbit. If you over-shoot and put the orbit out too far, when you encounter it you'll be going too fast. This applies for all intercepts, except on places with an atmosphere because if you're aerobraking it doesn't really matter if you come in too fast. It's especially critical though for low gravity places like gilly, because their SOI is small so you only have a limited time to slow down into an orbit.

[Geschosskopf]

thanks guys, my problem has been the capture. i seem to be hitting it to fast

Yeah, orbital velocity around Gilly is only like 15m/s even when scraping the hilltops so if you get there with a lot of speed, you'll either zoom by or have to burn huge amounts of fuel to capture. To avoid these problems, I aim to encounter Gilly when it's way out near its Eve Ap, so both it and my ship are moving very slowly. Also, I aim for the shallowest crossing angle between its path and mine. These 2 things make my ship arrive with very little relative velocity compared to Gilly, so capturing there is a breeze.

To make this happen, I do the following:

1. Aerocapture at Eve into a huge elliptical orbit with an Ap about equal to the MINOR axis of Gilly's ovate orbit.

2. Coast out to this Ap and circularize there. My orbit thus overlaps Gilly's, sticking outside its at the Eve end and cutting inside its about in the middle. As shown here:

3. Match planes with Gilly. Hugely important because Gilly's SOI is so small that you'll never hit it if you're having to do vertical as well as horizontal node fiddling.

4. Now it's a questions of fiddling with a maneuver node to get an intercept out near Gilly's Ap. This can be a bit time-consuming because getting your intercept depends on the phasing you have with Gilly after you establish your orbit, which is a matter of luck. I always start this process with the node on Gilly's Pe side of Eve as shown in the pic above. That way, as I pull on the prograde gizmo and my orbit expands, it crosses most of Gilly's path out toward the Ap end. You'll probably get several encounters at different places as you fiddle with this. With any luck, one of them will be out near Gilly's Ap and at a pretty shallow angle, like that shown above.

5. If you don't get a good encounter this way, you need to change your phasing with Gilly. Do a small burn at where the node's shown in the pic to make your own orbit a bit egg-shaped with its major axis more or less parallel to that of Gilly's. Go around this orbit and when you return to the Eve end, put a node there again and repeat step 4.

[magnemoe]

One point You want to orbit in high Eve orbit, if your Eve intercept is good it will not be economical to aerobrake around Eve as you use more fuel lifting your orbit enough for an Gilly intercept than you earn aerobraking. If your Eve intercept is bad you might want to aerobrake anyway.

You might want to burn without getting an clear intercept and fiddle later if its close together and close to Gilly Pe.

you want an wide lander as Gilly is hilly and its hard to see how the hills on the map.

You might also want to do something unusual, burn towards it during decent as the gravity is very low.

[Geschosskopf]

One point You want to orbit in high Eve orbit, if your Eve intercept is good it will not be economical to aerobrake around Eve as you use more fuel lifting your orbit enough for an Gilly intercept than you earn aerobraking. If your Eve intercept is bad you might want to aerobrake anyway.

This gets back to the same point, though. No matter where you're going, it's always going to be easier (as in cheaper dV-wise) to capture if you arrive there with as low a speed relative to the target and on as parallel a path as possible. Which of course depends on how well you set up the encounter beforehand.

When going to the inner planets, it's relatively hard to get such a good encounter, but it's incredibly easy to get a bad, high-speed, high-angle encounter. This can make for HUGE capture burns, as most folks discover on their 1st trip to Moho . Eve, however, has a great atmosphere for aerocaputre, so if you have a bad encounter there, it's usually cheaper to aerocapture into high-Ap orbit then raise your Pe to match, than it is to burn into such an orbit. But I do agree; if you've got a good (as in low relative velocity) Eve encounter, then you're probably better off staying out of the atmosphere.

[radonek]

Actually, I consider word "burn" huge overstatement when it comes to Gilly landing. RCS power is more then sufficient to bring decent lander down smoothly.

This can make for HUGE capture burns, as most folks discover on their 1st trip to Moho .

Amen. Delta-v encountered there is still hunting me in my dreams :-)

[capi3101]

This can make for HUGE capture burns, as most folks discover on their 1st trip to Moho .

Amen to that...learned that one myself just last night.

I have been to Gilly before, and I did it after winding up in an ugly polar Eve orbit. The trick there was to eject in the vicinity of the ascending/descending node (I forget which), because in that case it was the only place where the orbits could intersect. I was lucky enough to get an encounter after only a couple of orbits once I began trying.

You have to come in low for an encounter with Gilly - I think it's SOI only goes out to about 90 klicks or so. Its orbital velocity is also ridiculously low, something like 12-15 m/s or so. Landing on RCS thrust is cake (and as I recall, that's how I ultimately did it - it's the only world in the Kerbin system I've visited so far where, during the landing process, I deliberately applied thrust towards the surface (to speed the landing process up). I don't have pictures of the lander but I do remember it was during my "universal lander design" kick and I've got a parts list for it. That twenty-tonne lander was waaaaay overdoing it for Gilly.

[CrazedGunman502]

Does anyone find it funny that Gilly has extremely low gravity, while Eve is such a pain to get off of?