Zhetaan

Nicely done. Going to Eve was the best thing you could do. Congratulations on figuring out how to save the mission!

In fairness, you can do that without the MPL or contracts if you're willing to grind a bit.

It is, but there are good reasons for that. Changes to inclination are changes in the direction of the velocity, not changes to the magnitude, but since changing the direction of a velocity in a practical sense means cancelling the velocity in one direction while adding an equivalent in another direction, the most advantageous time to do it is when the magnitude is as small as possible. An extremely elliptical orbit has an extremely small velocity at apoapsis, so it is the most efficient to make the change there. That is dependent on the periapsis of its present hyperbolic orbit and a value called its hyperbolic excess velocity. The essence of it is that the hyperbolic excess velocity is the velocity that it has beyond escape velocity, and the periapsis distance affects the eccentricity of the orbit. Because the asteroid started in a solar orbit very nearly identical to that of Kerbin, the hyperbolic excess will be close to zero; however, whatever it is, you will need to shed a corresponding amount of velocity in order to effect a capture. The periapsis distance will determine how effective your burn is to make that capture; the closer you can get to Kerbin, the better, but given the size of the asteroid, you may well need to make use of what you have and hope that it is enough. However, you are probably in a very good position to change your periapsis; it isn't the best possible, but you might want to see what you can do with a small normal/radial burn just inside Kerbin's sphere. Normally, radial burns are wasteful, but this is one time that they can be useful. You are correct in that a rotation about the line of apsides (which is the 'apoapsis burn' you referred to) will not necessarily change the inclination. Changes to inclination are absolutely dependent on the line of nodes (that is the line connecting the ascending and descending nodes, the axis of rotation about which inclination is measured, and thus the reason why inclination changes are best made there), and burns at any other point will only change the inclination to the extent that the line of nodes projects to the point of the burn. In a more intuitive sense, it means that if the apsides are located above the poles of the planet, then no burn at those apsides can change the inclination, because rotating a polar orbit about the poles will naturally result in an orbit that still goes through the poles--i.e., it will still be polar. To fix that, you need to rotate the apsides of the orbit to the equatorial plane (the specific orbital parameter that you need to change is called the argument of periapsis). There are a few ways to do this: one is to burn at the periapsis to capture, burn again at the periapsis to circularise (this doesn't need to take two burns but it may be necessary to keep the burn from being too long), burn to raise the apoapsis from the equator, burn at the apoapsis to change the inclination, and finally, burn at the periapsis to circularise (or burn for the first part of a transfer to a different orbit). There are ways to increase the efficiency; for example, burning for as low a periapsis as possible as early as you can will save a lot of delta-V on later manoeuvres. You may also be able to influence the location of the periapsis with a few creative burns very close to the sphere edge, and that can save propellant later by reducing the adjustment. For another example, the really important thing is capture; once you have that, you can rendezvous with the asteroid at your leisure with whatever equipment you think you might need. For yet another, you may be able to get a lot of free delta-V from Mun gravity assists once you have an equatorial orbit, though that can be tricky. Because the initial orbit and the first stage intermediate orbit (the orbit immediately post-capture and the orbit with the apoapsis at the equator) have the same size and shape (semi-major axis and eccentricity) and share the same orbital plane (they have the same inclination and longitude of ascending node), they necessarily must intersect at two points. It is possible to get a single-burn solution to change the argument of periapsis at one of these points, but it is expensive. I do not know how expensive it is, but it involves radial velocity, so the answer is 'too expensive for your rocket'. From my limited research on the subject, it appears that the delta-V cost is the same at either intersection point, which is a bad sign; I expect that the single-burn manoeuvre has a cost well into the thousands. There is also a two-burn solution involving tangential ellipses; the idea is that for any two distinct coplanar elliptical orbits, there is at least one other orbit that is tangent to both of them, and the elegance of that is that moving from one orbit to a tangent orbit requires only prograde/retrograde burns. You may also recognise this as a generalisation of the Homann transfer orbit. For this reason, I suspect that it is potentially the cheapest of the alternatives, but I must confess to only passing familiarity with the theory; I have never attempted it for myself. To reiterate, the first priority is to capture the asteroid because you can then take the time to equip it properly before attempting further refinements to its motion.

I tend to dock with what's in the cockpit or pod on-board tank. If I have an exceptionally heavy payload or other factor that calls into question whether I'll need more, then I usually include the extra with the payload, either as part of it or at least in the docking bay. However, I also use Kerbal Construction Time, which rewards minimal redesign for recoverable craft; I have a strong incentive to include extra anything with the payload. Admittedly, I have been docking for a long time, but the thing to remember is that there is a tremendous gap between the on-board tank and the same-size monopropellant tank; the dedicated tanks are absolutely enormous compared to the typical need. If you need one, then you need only one.

They blink when you do. You see it in the cinematics and still photos because those are recordings. But when you're playing the game with 'live' kerbals, they blink when you do. Don't try to catch them doing it; they'll know.

I'm suggesting this without having tried it, but have you considered autorotation? Arrange winglets or fins (AV-T1 Winglets mass 37 kg and Basic Fins mass 10 kg) around your probe body to convert some of your linear velocity to angular velocity. If that isn't enough, then use the reaction wheels to counter-rotate and lift against that air. I'll leave it to you to determine the best angle and placement, or to decide whether this will work at all.

For the most extreme of stable elliptical orbits in Kerbin's sphere of influence, where the periapsis is at 670 km and the apoapsis is at 84,000 km (those are centre-based radii, not surface altitudes), the orbital velocity at apoapsis is 25.8 m/s, so the delta-V to change the inclination by 90° is 36.5 m/s. For a circular orbit at 84,000 km near the sphere of influence edge, the orbital velocity is 205 m/s, so the delta-V to change inclination by 90° is 290 m/s.

In addition to @Streetwind's recommendation that you mine the asteroid, you may consider lowering your apoapsis more. Your periapsis velocity (neglecting air resistance) is almost a thousand metres per second greater when your apoapsis is at a few thousand kilometres than it is when your apoapsis just outside Kerbin's atmosphere.

You raise a good point but for the fact that the midpoint of that manoeuvre is the perfect place to burn for capture. The issue with burning while attached in atmosphere is that the vessel doesn't have the control that it needs: Nervs thrust at only 60 kN--less in atmosphere--and 1,300 tonnes provide a lot of turning resistance, so if the asteroid swings to a bad direction, there isn't anything to do but wait it out and lament the lost opportunity. That's assuming that the vessel was designed to enter the atmosphere at all, which it may not have been. Also, asteroids, as giant, dense rocks, have reduced drag because of their mass, so aerocapture, though possible, may not be plausible. That all being said, I think that it's worth a try, but perhaps is best considered a last-resort approach. I won't discount the idea entirely without trying it for myself, but allow me to point out that if detaching, chasing, and reattaching are plausible ideas, then so is launching a more powerful tug equipped with Vectors or Rhinos and using that. Also, I know that asteroids in the past have tended to be made of concentrated explodiboom when it comes to aerocapture from anything other than low orbit, but perhaps they've seen an update to their thermal tolerances. Edit: Apparently, given another question in this forum that involves several aerobraking passes with a class D, they've fixed the explodiboom problem. I'm still not convinced that this is the best approach, but that particular objection, it seems, is unfounded. That's a great idea for asteroids that intercept with near-zero inclination. Unfortunately, this asteroid's polar flyby will offer precious few opportunities to attempt a gravity assist and less effect from one should the encounter actually happen. It is possible, but there is exactly one Kerbin-Mun configuration that will work for a polar approach. @TanDeeJay, if the asteroid will fly by the Mun in such a way that the Mun is moving directly away from it, then this is an excellent idea and may even give you a capture, since the Mun assist is worth a few hundred m/s--provided that you can get one. ----- The best suggestions that I have to offer are to pick your targets with care and to learn that patience is the key to orbital mechanics. There are new asteroids every day; choose those that are cheap to manoeuvre. Tugs are generally not worth the cost anyway, because propellant is rather cheap on Kerbin's surface. You save more money by refuelling a vessel already in orbit (meaning that your entire fleet, not just the tugs, are reusable) because you also save all of cost of the launch and second stage hardware that you no longer need to build. The main reason for ISRU is convenience, not cost: LFO propellant costs 91.8 Funds per tonne--Liquid Fuel alone is 160 Funds per tonne if you're using only Nervs--but assuming that you're refuelling LFO rockets, you'd need to refine and transfer 5,230 tonnes of it to cover the cost of one of your tugs. Let's call that four of @TanDeeJay's Class E asteroids--except that it's more, because asteroids are not made of 100% Ore. You make it more worthwhile with monopropellant (300 Funds/tonne) but monopropellant is a mass loss--its density is 4 kg/L, not 5 kg/L as LFO is. Also, you won't ever need that much monopropellant unless you're trying to waste it.

Yes and no. As @Spricigo mentioned, you can both reduce your asteroid's mass and increase your delta-V by converting part of it into propellant. Also, the amount that you convert will probably not add up to much of the asteroid, so expect this to be a resupply stop for a long, long time. But from a timing perspective, it isn't going to work. You can't convert enough in 13 days, much less whatever is left after you fast-transfer a mining rig to the asteroid. However, from a standpoint of 'go get asteroid' you're not doing anything wrong; you've merely taken a bite of something far larger than you anticipated. You might consider an immediate manoeuvre where you are (so that it is fairly cheap) to lower your Kerbin periapsis to just outside the atmosphere (approximately 80 - 100 km), and then another manoeuvre at the periapsis to close the orbit. That's it; just close the orbit. That way, you can reduce the inclination at the next apoapsis and circularise afterwards at whatever altitude you like. It may save enough propellant for you to accomplish it with the rocket you have, but should it not, it at least gives you a close Kerbin fly-by so that you can send an additional rocket with relative ease. Send a tanker, though, if it comes to that; as I mentioned above, you don't have time to refine the propellant that you need. It absolutely is possible, though the worst-case scenario is that you don't capture it this time. Since near-Kerbin asteroids all have orbits approximately equivalent to Kerbin's orbit, setting up a subsequent encounter shouldn't be too difficult. The question is one of timing. If you'll recall when you learned how to rendezvous, when you had two vessels in very similar orbits, it was often better to boost one to a markedly different orbit so that you could get an intercept in something less than geologic time. Unfortunately, that's not possible here because on the one hand, the asteroid is difficult to move, and on the other hand, Kerbin is impossible to move. On the gripping hand, unless you're running a life-support mod, you have the time to coax this one into orbit if you put aside the idea of necessarily doing it on this orbit.

Trajectories gives you a visual cue, but not an angle. You could combine that with Kerbal Engineer Redux and its latitude and longitude readouts to get something like the result you want. MechJeb may also help. There was once a protrator mod, but I don't know whether it would help you (I recall that it was more about finding phase angles for interplanetary transfer). Do remember that ground longitude and celestial longitude won't match because the planet rotates; the difficulty in dealing with that is probably why there is no single solution that I could find. A protractor on the screen may be your best choice for an on-screen tool, given the simplicity of it. Even the Apollo astronauts took a sextant.

I'm going to guess that you're using a mod like Kerbal Inventory System, which is linked. If that is what you are using, then know that it comes with an instruction manual, which is also linked, and everything about tools and attachment begins in chapter 6, on page 9 of the manual.

If you want to go to Duna for any purpose, including a gravity assist, then you need a transfer window. Your Kerbin-Duna configuration right now is terrible.

That was your hint. It's backwards. They are directional. Aside from the helpful pictures others have posted, one key to remember is that you don't want to see the circle with the plus sign in it. You can change it by EVA with a mod called Kerbal Inventory System, or KIS. That may take a bit of work; KIS can be 'fiddly' at times. If your backward-port module happens to be attached to the rest of the station by other docking ports, then you can simply deorbit it and send a corrected one. You can dock your giant tank to one of the small ports by one of its small ports, and you won't have a problem with drifting. If that means taking your station apart and building it around a new core, then I suggest leaving it in place until you send the new module. If you're truly at your wits' end, then it is possible to modify the save file to correct the rotation of the port. I don't normally advise this because it's easy to completely ruin your save this way, but it can be done. It's highly technical, though, and honestly may be more effort than launching a new station core--I'd be more inclined to tell you to try it to rescue a station at Moho or Jool. We're glad to help. Good luck with it, and please don't hesitate to come back. Also, welcome to the forum!

Certainly: It is the light pink area to the northeast of East Farside Crater, northwest of Farside Crater (no, I don't know why East Farside Crater is west of Farside Crater) southwest of Polar Crater, and due west of the north-south Canyons. I can verify its existence; I just drove a rover there from the east-west Canyons a few days ago.

Gravity has nothing to do with it. Asparagus works because it removes dry mass and thereby keeps your rocket's mass ratio high--in exactly the same fashion as other staging. The advantage of asparagus is that it allows you to use multiple engines but feed them from a common propellant tank (or tanks, since symmetry is important). You get the advantages of high thrust thereby, but without needing to sacrifice the efficiency of maintaining a high mass ratio. One reason that you might be concerned about gravity is because one of the key advantages of asparagus--high thrust--is important when fighting gravity. Using more engines for more thrust lets you escape the gravity more quickly, so asparagus definitely has an application there. In space, it is somewhat less useful, but it works quite well with drop tanks arranged around a core engine or cluster. Of course, once in space, you have the advantage of being able to use resource transfer while doing something other than trying not to flip or crash, so setting up the fancy asparagus ducting and all may add more mass than you actually need to get the same effect.

You are correct in that the Oberth effect does not explain all of the altitude gain, and I was in error to imply that it was. However, I believe the Oberth contribution to be greater than you suggest, but I confess to admit that I do not know by how much that is the case. The only thing I can think to do is to work through the entire calculation from a standpoint of kinetic energy and see where that takes us. Also please accept my apologies for the text wall in the spoiler. I had a difficult time determining which parts to hide and which to leave out, so I hid it all. So, to conclude, I submit this: *BAMF*, Oberth effect. But it's still there.

Part of the issue here is that you're dealing with one of the highest-thrust engines and one of the lowest-thrust engines in the same burn. The way to solve that is to split the burn according to delta-V rather than relying entirely on time. For example, if you had a burn of some (manageable) amount of delta-V (let's say 200 m/s for an example) and it worked out that the high-thrust engine had 100 m/s in its tank, then you would want to start the burn at a time early enough that you pass the exact node at the same time as you burn out and need to stage. However, higher thrust means faster propellant consumption, so in terms of time, the burn would be very lopsided in that you might burn the high-thrust engine for ten seconds and the low-thrust engine for a minute and thirty seconds. Normally, some error on either side of the node marker will have a negligible effect on the overall manoeuvre. In this case, the combination of its being an interplanetary trajectory and Moho's near-microscopic sphere of influence makes it difficult to hit precisely, and increasing the burn time (as you would do by using a low-thrust engine) unfortunately increases the potential for that error. There are techniques to address that (periapsis-kicking is one that you may be interested in knowing more about), and there are some other tricks that you can use, but that's the way with the challenge planets: you'll learn a lot by making a lot of mistakes. Do please let us know when you get the kerbals home. You should consider putting the story in Mission Reports!

The vis-viva equation emerges from the interplay of potential and kinetic energy in a gravity well and covers anything in any Keplerian orbit. Incidentally, the gravitational parameter is missing from the vis-viva equation that you quoted; it is not quite correct. The Oberth effect has to do with the kinetic energy of a vessel at speed but does not necessarily require an orbit. Insofar as they both relate to kinetic energy, they have a relationship with one another. Let me try a somewhat different illustration for this. Let's say that you are in a circular 100 km orbit about Kerbin, moving at 2,246 m/s, the orbital speed for that altitude. Let's say that you execute a thirty-second burn at some point on this orbit: your apoapsis rises, let's say from 100 to 200 km for this burn with this engine. This requires a delta-V of 74 m/s, so we're probably using an Ant for this for a burn to take thirty seconds, but the point still stands. Now let's say that you're on a 100 x 300 km orbit and you execute a thirty-second burn at the periapsis. This time, you're moving at 2,382 m/s, and an addition of 74 m/s results in an orbit of 440 km. The engine produces thrust from mass flow of its propellant; you develop the same thrust from the same burn time and the same amount of propellant. And yet your apoapsis rises by 40 km more than it did for the first burn. *BAMF*, Oberth effect. The rocket did not burn more propellant, but it was in a different situation; namely, the rocket was moving faster, i.e., had more kinetic energy, at the beginning of the burn. The Oberth effect is not a free energy device: it is simply an observation that if you have more kinetic energy to begin, then you can do more with it. Of course, that's true regardless of the energy type: you get more delta-V from carrying more propellant, too. If you kick the ball harder, then it goes farther, but if the ball is rolled to you faster, then you can kick it farther in that case, as well. Energy and momentum must be conserved, but if you start with more of it, then the conservation results in the individual pieces of the system all getting a larger share.

I can't mark a difference between 1 and 2. The value that you refer to as v is noted in a lot of places as vinf or v∞ and called the hyperbolic excess velocity. It results from breaking the transfer injection into two parts: the first is escape from the origin body, and the second is the remainder of the transfer--this second part is what v∞ is. Because of its nature, it is specific not only to the planets involved in the transfer, but also to particular transfer windows. It absolutely can be figured analytically, but that problem is functionally identical to the one solved by a transfer planner.

It depends on the insertion altitude. Escape velocity is dependent on orbital altitude, which means that the inverse of it, what I will call capture-to velocity, is dependent, as well. This means that you can't simply choose an apsis just above the planetary surface, compare it to an apsis at the extreme edge of the sphere of influence, and assume that there is a linear relationship between the two. It may work out that an extreme is also an ideal (and, with utmost respect to @Grogs, Moho is an extreme-enough destination that I suspect it works out that way there), but in most cases, using two extremes is only extremely inconclusive; you can't interpolate from that. We have to go farther into the data. @OHara has the correct idea with respect to gate orbits; as there is an ideal altitude from which to make a dive to get maximum gain for the Oberth effect on ejection burns, so too, is there an ideal insertion altitude for capture. This part does require that the periapsis be as close to the planet as possible, but the point is that, assuming that you can start at a given altitude (so this does ignore the cost of launching to that orbit in the first place), the best altitude from which to make the dive is not necessarily at either extreme of the sphere of influence because there is a balance to be struck between the savings of going faster for the ejection and the costs of de-circularising. Starting closer to minimum periapsis means lower costs for de-circularising but less speed, and thus less Oberth effect, at the ejection burn, but starting closer to the edge of the sphere of influence means spending so much to dive that it eclipses the Oberth effect savings. Since this is true for the ejection, it must be equally true for the capture, because physically, the two manoeuvres are identical. Therefore, diving to low altitude and capturing to an orbit with an apoapsis of some specific altitude for purposes of later circularisation can be more efficient, provided that the target apoapsis is close to that ideal altitude. There was an extremely illuminating post from @OhioBob on this subject five years ago. I can't explain it better than he can, and he also provided helpful graphs, so here's a link to the post:

As others have said (@N_Danger & @OHara), you have wheel controls mapped to the same keys as your reaction wheel rotation controls. There are several options to deal with this: Set the reaction wheels to respond to 'SAS Only', as @Streetwind suggested. This way, you can use stability assist to keep your rover somewhat level in case you drive off a rise or otherwise need some anti-flip control. Shut off the reaction wheels entirely. Then it won't matter that the keys are double-mapped. You can do this with action groups, if you like. Build a rover that doesn't have reaction wheels; the RoveMate probe core doesn't have any. Re-map your rover wheel controls so that they do not share keys with other controls. I prefer to use 2-4-6-8 on the number pad, with 5 as a second brake control, but the translation controls I-J-K-L will also work if, for some reason, you do not already have them mapped as secondary wheel controls as is the default. I prefer not to use the translation controls because for technical consistency, I expect forwards and backwards to be controlled by H-N, not I-K, but that's only a peculiarity of my preference. I suppose that you could technically remap your rotational controls instead, but no one ever seems to do this. That won't make any difference. Assuming that you have an upgraded VAB (or are using Sandbox or Science mode), you can set action groups to toggle between reaction wheels and rover wheels so that you don't have to watch wheels spinning blindly in space while you're trying to fly it, but simply having rocket parts on your rover won't change the control scheme (after all, rockets whose final stages are rovers are the only way to get rovers to other planets--even docked rovers are part of the same vessel). Good luck!

Welcome to the forum, @pranavsuri! You can do this, certainly. There are several ways to go about it, but fortunately for you, most use the cheat menu for experimental repetition, so you don't need to learn about design principles when you're only interested in learning about orbital mechanics. The obvious route, I think, would be to take a standard probe with a standard (small) propellant load, place it in a variety of orbits using the Set Orbit cheat function, burn it from full to empty, and measure the effects; however, I hesitate to assume anything about the nature of your essay or the data that you specifically seek to collect.

This is correct; assuming that you don't need to start from a high orbit, it's usually better not to do so because the savings from starting in low orbit, with its higher velocity, outweigh most other factors. The reason is because you are still in Kerbin's gravity well. As you climb out of the well, Kerbin's gravity warps your trajectory, so you need to change your starting point so that Kerbin warps your exit beneficially, in order that you leave Kerbin's sphere of influence parallel to Kerbin's prograde vector and have an efficient transfer. In other words, rather than starting at the 'right' point and having Kerbin warp your trajectory off-course, you deliberately start 'off-course' and let Kerbin correct it for you. The farther you are from Kerbin when you start, the less it warps your trajectory. Eventually, you escape Kerbin entirely and begin from a solar orbit, in which case you would just burn prograde to reach outer planets. You also lose on the advantages of a higher initial velocity, and as I mentioned above, those are normally more valuable. It's about the velocity, first and most importantly. Duna is closer than Dres, so your hyperbolic excess velocity (for practical purposes, that's the velocity that you have at Kerbin's sphere of influence boundary that is over and above escape velocity) is going to be lower for Duna because you're transferring to a lower solar orbit. It is true that the more powerful your burn is, the less you need to adjust your ejection, but that's because a more powerful burn results in a higher Kerbin-relative velocity, which results in less time spent in Kerbin's sphere, which results in less time for Kerbin to warp the trajectory. Your angle will affect how far you eventually fly from the sun, but not because the burn is more or less powerful--burn for the same amount of time at different ejection points, and a burn that sends you to Moho from one point will take you past Jool from another. Let's say that you want to go to Duna; you neither need nor want a burn that, at a different angle, will take you to Jool, because you either want that propellant for use at Duna or else not to take the extra mass. There is a trade-off: if we assume that you have enough propellant to reach Duna from half, or nearly half, of possible ejection points from Kerbin (half because the other half will send you in-system rather than out), then for most of those points, you will not only reach Duna but will also fly past it in a classic case of having too much propellant for the task at hand. If we reduce the propellant for the burn, then the angles that will allow you to reach Duna become constrained because the most inefficient angles at the extremes of the arc will no longer send you quite far enough to get to Duna's orbit. Eventually, you reach one point at a specific angle that will get you to Duna for minimum propellant cost. Any other angle would require more propellant, and any less propellant will see you fail to reach Duna no matter where you burn. That point is the burn point, and that angle is the ejection angle. This is exactly the same reason why we prefer prograde/retrograde burns to radial ones for transfer manoeuvres. Your ejection angle tells you the right place to burn so that your eventual exit to the interplanetary transfer orbit is as parallel to the planet's prograde/retrograde vector as possible, such that it makes the burn fuel-efficient. Burning off-angle is exactly the same as burning off-prograde in the more local sense. There may be reasons to do it (adjusting arrival times for a flotilla of probes so that you're not capture-burning all of them at the exact same time, for example), but those reasons don't often have anything to do with efficiency.

Assuming a reasonably optimised transfer to Moho from Kerbin, going directly to 50 km from Kerbin-Moho insertion saves approximately 195 - 200 m/s over going to 500 km--and that's before the additional burn to adjust the 500 km orbit down to 50 km, which costs an additional 262 m/s.