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(This was first posted on the Space Exploration StackExchange and the AskScienceDiscussion subreddit first, but I want more input, so I'm posting here as well. As forewarning, the most integral details of this question are bolded.) For context, I have been writing an alternate history involving the accelerated development of spaceflight technology for over 5 years now (one with quite different assumptions from other examples of the subgenre), and one of its long-standing elements has been a wildly-ambitious space probe that would be sent on a Solar System Circumnavigation through a Grander Tour. What does this mean? Well, here are the mission objectives: The main spacecraft body (which I will obfuscatorily name “the Spacecraft”) must fly by every planet (1930–2006) in the Solar System save Pluto. At least a subprobe (“Subprobe A”) must fly by Pluto. Double points if it manages to do so while flying by all 8 other planets. A sample, no matter how miniscule (probably micrometeorites or ring particles), must be returned to Earth by a subprobe or sub-subprobe (“Subprobe B”) after flying by all 8 2006– planets. The course correction to do so may involve as much as an orbital-scale (~9000 m/s) multi-stage solid rocket together with aerobreaking and/or a brutal gravity assist. Double points if it is on or launched from Subprobe A. Triple points if it is on or launched from Subprobe A after the Pluto flyby. Each flyby in the Outer Solar System should preferably be at least 1 synodic period before that of the real-life Grand Tour users the Voyagers in order to prepare for the arrival of a vaguely equivalent program. The base of the spacecraft’s conception was that it would be launched around the time of or before the first outer planets and interstellar probes in real life (Pioneer 10/11) to make time for it to engage on a more proper Grand Tour trajectory. This was reinforced by the fact that said time range roughly overlaps with the 450th anniversary of an Earth circumnavigation expedition done by the crew of a certain navigator, who happens to be the namesake of a far less impressive real-life space mission. So, the rock-hard minimum and maximum are the 450th anniversary of the start of that navigator’s voyage (September 20th, 1969) and the launch of the latter Pioneer, Pioneer 11 (April 5th, 1973). However, it would ideally be launched before September 6th, 1972, exactly 450 years after what was left of that expedition returned, yet as close to that date as possible (i.e. within 1972) to allow as much advanced technology to be used in it as possible—the spacecraft would include developments like 8-bit microprocessors, helical-scan tape data storage, robotic arms, synthetic aperture RADAR, and possibly non-solid-state radioisotope generators. And yes, the first asking of this question was deliberately timed to match with the 50th anniversary of that date and the 45th anniversary of the launch of Voyager 1. (I’d have preferred it to be earlier, but ehh…) Also, the spacecraft’s original conception had it launched on a Saturn IB–Agena D (what I thought was the highest-capacity high-velocity non-Saturn V notional “drop-in” vehicle that could have been made at the time… ignoring that either a Saturn IB–Centaur or earlier Titan IIIE would have greater capacity and could probably be made with similar R&D), but as its size and capabilities grew, its proposed launch vehicle was progressively upgraded until it became the “Saturn 1E-SB”, which consists of 4 stages (more details on which could be provided if required), the last one, not considered integral to the launch vehicle’s identity, being the main course correction stage of the spacecraft. The first 3 stages would have the capability to put the 4th stage and ~5.5-ton spacecraft complex—~28.5 tons in total and ~6.75 tons dry mass—on a trans-Cytherean or potentially trans-Martian injection (up to 3650 m/s tested in KSP RSS RO using a penultimate version of the launch vehicle, probably ~3800 m/s), beginning its Grander Tour… A Saturn V could do so, too, and to be honest I now find justifying the existence of the Saturn 1E-SB somewhat difficult, so I may bite the bullet of switching away from a “Saturn one” platform. Now, how much ∆v would the course correction stage be capable of supplying? A measly… ~5500 m/s. And that’s with the subprobes still attached. So there is a very beefy, though not unlimited course-correction capacity. Now, orbital mechanics is a complex business, and I don’t know if it would even be possible to fulfill even the barest mission requirements given the ∆v budget within that launch window, let alone how it would be done. However, the existence of trajectory designs like this, a flyby of all 2006– planets launched in the same vague timeframe with a negligible course-correction budget, indicates its likely possibility. Note that the 5500 m/s and 5.5 tons payload is a maximum and minimum, respectively—the more optimized the trajectory can be made, the smaller the fuel mass of the course correction stage needs to be, allowing a greater scientific payload, so the more optimized the mission is, the better. And so, the question. Ideally, I’d like to have the specifics of this drilled down by April 5th, 2023 for some sense of timeliness. For more context, this is the encounter order as planned when the conception of this mission reached its modern form: Main spacecraft: Earth→Venus→Mercury→Venus→Mars→Jupiter→Saturn→Ouranos→Neptune→Interstellar Subprobe A: 〃→〃→〃→〃→〃→〃→Pluto→Interstellar Subprobe B: 〃→〃→〃→〃→〃→〃→〃→Ouranos→Neptune→Earth

I've been having trouble rapping my head around slingshot maneuvers. Enter Sphere of Influence (SoI) and exit SoI with changed velocity. It basically breaks down to four maneuvers. A and B are from a higher (faster) orbit, C and D are from a lower (slower) orbit. A and C are leading the object, B and D are trailing. There are some hints in https://wiki.kerbalspaceprogram.com/wiki/Tutorial:_Gravity_Assist It shows C and D. but what about A and B? Which ones will increase my exit velocity? C Which ones will decrease my exit velocity? D

This project has been abandoned in lieu of a newer, much more usable implementation: KSP Transfer Illustrator Links KSP Transfer Illustrator KSP Trajectory Illustrator Description Inspired by existing mission planning tools (alexmoon's Launch Window Planner and Arrowstar's Trajectory Optimization Tool), I have made a couple of web apps to help visualize trajectories for mission planning. While the KSP Trajectory Optimization Tool is much more powerful and has many more features, the idea is that Transfer Illustrator can be used without downloading or installing any software and has an unintimidating user interface. I've also tried to make this app have some additional flexibility compared to the Launch Window Planner and to make it easier to interpret the information provided about orbit parameters and burn information. KSP Transfer Illustrator: Generates Porkchop plots to visualize Δv costs for transfers across a range of departure and arrival times Computes transfers between spheres of influence (e.g. Kerbin to Duna) or within a sphere of influence (e.g. two distinct orbits around Kerbin) Determines optimal times and magnitudes of plane-change maneuvers during a transfer Determines ejection/insertion trajectories for transfers that involve exiting/entering a body's sphere of influence Displays interactive 3D plots of the calculated trajectories Creates downloadable HTML files with the interactive plots Loads orbit data from KSP savefiles The KSP Trajectory Illustrator: Propagates trajectories across spheres of influence Computes orbit changes at (instantaneous) maneuver nodes Creates interactive 3D plots showing trajectories of multiple crafts/objects Reads flight data directly from savefiles Plans for this project While the apps are already in a usable state, there are several improvements I plan on making: Find a new way to deploy the app (the free version of Heroku I'm using has issues with worker timeouts during long computations) (Performance has improved to the point where this isn't a huge issue) Add UI elements to help copy and save orbit details Add more robust support for other solar systems (e.g. Kopernicus) Find way to allow interactive plots to be embedded in forum posts (Not possible due to security concerns) Make the app a bit prettier More robust plane change maneuver options (90 degrees to intercept vs. AN vs. DN, inspired by this post) Gravity assist planning This is my first project in Python and my first ever attempt at making a web app, so there's probably a lot that I can do to improve! Any suggestions or advice would be appreciated. Also, if you come across any bugs or incorrect results when using the app, I would appreciate feedback in this thread or on the project's GitHub repository. Please share any requests for new features! The KSP Transfer Illustrator is licensed under the MIT License.

This one has been nagging me for a while thanks to the STS challenge. In order to get the best rank, you need to land your shuttle back at the KSC (or other runway structure on Kerbin). When you're tooling around in an equatorial orbit, this is easy enough, since you're always more or less aligned with the position of the KSC. But when you get into the more advanced missions, you need to perform activities out-of-plane and still return to the KSC; I've been solving this by simply doing a plane change burn, but that'll be less viable as I head out to the Mun and beyond. I've tried to nail the KSC from an inclined orbit a few times, but I can never seem to get it. Thus, my question: how would I directly return to the KSC from an inclined orbit?

Hello dear reader Which is better and more fuel effecient? I remember hearing about the Dn and An but I don't know which one is more effecient.

The title is pretty self explanatory. I want to find the general equation to calculate the payload capacity of a particular rocket (with a certain delta-v) to an orbit of x X y km with a Beta inclination around a planet of radius r and mass M. I hope to find a solution for an airless body before moving on to bodies with atmosphere. Thanks in advance!

I'm trying to do as much as I can with KOS in this career, which means actually working out what's going on rather than just eyeballing it with the manoeuvre nodes. Calculating the dV and phase angle to get to the Mun is easy enough, but I can't get my head around coming back. I know from previous experience that 250ish m/s at an angle somewhere between pointing at Kerbin and Mun retrograde will get me the most efficient return to Kerbin atmosphere, but can't see how to work it out. For a given Ap altitude above Kerbin I can work out the velocity I need to achieve my required Kerbin Pe, and for a given ejection burn I should be able to calculate the velocity and altitude relative to Kerbin at the point it leaves the SOI (not done this yet but I think I know how), but as the required Kerbin velocity will change with Ap altitude I can't see how to link the two together. Any suggestions?

Why KSP engine doesn't support parabolic trajectories? (You can try to put e = 1 into HyperEdit and see disappearing ship) What meaning of negative Apoapsis? I understand what it is about hyperbolic trajectories, but still, what its physical meaning? lim Ap = +∞ e → 1⁻ lim Ap = −∞ e → 1⁺ It is the reason why you get NaN if you put e = 1, but something wrong there. How it works in big science?

This thread is for the discussion of Aldrin Cycler Ships. First of all, an introduction to the topic- since most readers on this forum are undoubtedly unfamiliar with the concept, and the last time I wrote about it (many months ago) I received a lot of responses from people who clearly had no idea what they were talking about... Please read ALL of the following first, before commenting, I would really appreciate it. None of these are that long, and are only meant to provide a preliminary introduction to the topic: https://en.m.wikipedia.org/wiki/Mars_cycler https://buzzaldrin.com/space-vision/rocket_science/aldrin-mars-cycler/ https://space.stackexchange.com/questions/3880/what-uses-would-the-aldrin-cycler-have And, for more context I HIGHLY RECOMMEND reading these articles: http://www.popularmechanics.com/space/moon-mars/a333/2076326/ https://www.damninteresting.com/the-martian-express/ Please read through at least the first three links, and the fourth and fifth ones if you can, and let me know your thoughts on the concept: advantages or disadvantages, synergies with other approaches/technologies, etc. Regards, Northstar

Help me please, I think my game is glitching out. I'm playing with galileo's system replacer, using a station and a probe. I've put the station in the same orbit as Lili but shifted ahead (a large asteroid in the belt of a large planet) and want to use the probe to find ore deposits. the station is in a stable position - I've accelerated time and watched them orbit, they stay the same distance apart. The trouble begins when I actually go to use the probe. I get it into a capture of Lili, and then the station's orbit changes. it goes from stable and separate to falling straight down to the planet, and when I use Hyperedit to place it back in the same orbit as Lili, it starts Falling towards it. I've looked at the velocities, and they're the same. Lili is orbiting at 455,000m and 3578.5m/s, I'm orbiting at 449,000m and 3578.5m/s. When I switch to target mode, I'm moving towards Lili at around 200m/s. How can I be moving in the same orbit and same velocity as a celestial body AND be falling towards it? also, when I fall towards it my orbit doesn't show a transfer into Lili's SOI, I just crash and explode. Can anyone explain what is happening?

(Inspired by Interplanetary How-To Guide by Kosmo-Not) I proudly present to you the Nexus's Orbital Calculator It does a lot of calculations for you automatically. You only have to input the data. It has a: Orbit Calculator Hohmann Transfer Calculator Interplanetary Transfer Calculator And more... Works for both stock KSP and Real Solar System Download for free by clicking on the link below https://drive.google.com/file/d/0B0WLcnclj_TFSVBRUEExSWlmeW8/view?usp=sharing (I'm open to constructive criticism and suggestions)

I've taken on the project of writing an interplanetary trajectory optimization tool and a comparison of algorithm efficiency for the problem at arbitrary starting points. Looking further into the problem, however, I have a question that I can't seem to answer. When you optimize an interplanetary trajectory in a patched-conics approximation like KSP, how do initial and target orbit influence the problem? Specifically, I understand how the 'interplanetary' part works. Given the position of two planets, you can calculate the orbit that will intersect one position at one time (the departure date) and the position of the other at another time (the arrival date) easily by cranking through Lambert's Problem for the solar orbit case. However, how do you account for leaving the orbit of the start planet and arriving in orbit of the destination planet? Put another way, how do you calculate ejection angle or the optimum burn to leave/enter the patched conic gravity well?

I'd like kOS to calculate the velocity at periapsis for me with the apoapsis height, periapsis height and apoapsis velocity as variables. However, if one is using the specific orbital energy v2/2 - µ/r = constant, you must know the standard gravitational parameter. I could hardcode the values into my script for every celestial body, but I want it to be as general as possible (if you decide to alter the default masses with mods etc). How do I get rid of the dependency of µ in my formula?

https://www.playhellion.com/ Incredible new space sim/survival/orbital mechanics/multiplayer game. Early access is coming out next week. Looks absolutely fantastic! Any KSP players dream come true. Check it out, and spread the word!

Suppose two countries with all of the technologies we expect to have by the year 2150 exist on Ganymede and Europa. They cover the whole of their moons. They have giant vertical underground farms to sustain themselves and huge solar fields with almost 100% efficiency (virtually no energy (light, heat, vibration, etc.) is missed or wasted). They have mining running down to the cores. They have big cities like on Earth, mostly underground. And they go to war with eatchother. No prisoners. No survivors. No slaves. Total annihilation. How is it fought? What are the advantages of Europa over Ganymede?

I'm a newbie in career mode and have hit a roadblock in attempting to fly by and gather scientific data near the Mun - I've followed Scott Manley's tutorials on how to do this, but I'm doing something stupid because I can't succeed - after achieving a stable orbit around Kerwin, I place a manuever node 90 degrees ahead of my target (Mun) - no matter how I try, I cannot get a projected orbit to get closer to the Mun than 2429.6 km - no matter how many ways I try to do it (ahead of it, behind it, near it), the closest approach miraculously stops at 2429.6 km - also, the application is so sensitive as I increase the projected orbit near the Mun that I instantly "pop" into a totally different orbital arrangement (is that the effect of the Mun's sphere of influence?), but still keeps me 2429.6 km away from it - and finally, is there a way to zoom in on the projected near encounter of the Mun in map view? Mine remains centered on my spacecraft and when I try to zoom in the "spaghetti" of orbits near the Mun I only zoom in on my spacecraft so it is impossible to analyze what my projected path(s) are doing very easily. Sorry for all the questions - I love the application but I'm up against a "wall" that's preventing me from advancing - the issues are exactly the same in sandbox as well as career mode. Thanks in advance for anyone's assistance/suggestions.

how does mission control calculate where you will end up and how map calculates this. like for translunar injection how do you know how your orbit is by not using map mode

Hello! This may sound silly but with all my years playing ksp, having bought it several years ago, when the game was just about the extent of the demo now, ive never acquired a true geostationary orbit, is there any way to place a ship or satellite in such an orbit without the use of mods, does KSP have a feature or something else to help a craft into such unique orbits, thanks!

Hey guys, understand this is a bit of an ask but I've come to the end of my tether with trying to calculate these. If any of you are nerdy enough to give these a go I'd greatly appreciate it. http://prntscr.com/d52ktz?

Let's keep it simple: Arrive at Minmus SOI from Kerbin. Hyperbolic orbit with perigee at 150km, generally equatorial. Desired orbit is 15km x 15km, equatorial. I can play this two ways: 1) Immediately burn retro, dropping Pe to 15km. Then burn retro at Pe to lower Ap to 15km. 2) immediately burn nadir to tighten Pe down to 15km. Then burn retro at Pe to lower Ap to 15km. What at is the difference? What is the trade off between the two methods? Would (1) actually effect entry speed in a meaningful way, if it were Duna and not Minmus? Would (2) provide more of a boost if I was only using the encounter for a slingshot? These are my suspicions, but I find it hard to quantify any F5/F9 results. When should I be employing which method?

I just installed the Outer Planets Mod and am trying to figure out what kinds of Δv's I'll need to reach those planets. I began setting up a spreadsheet to calculate the required orbital velocities, but something's not right. The standard equations are giving me a reasonably accurate orbital velocity of 2,295 m/s at 70 km above Kerbin, escape velocity of 950.7 m/s and orbital velocity around Kerbol of 9,282 m/s. However, when I plug in the average orbital distance of Duna (2.07 × 1010 m) and try to calculate the Δv necessary to raise myself from periapsis at Kerbin orbit to apoapsis at Duna orbit, no matter which variation of the equation I use (I've found three), I keep coming up with a Δv of about 918 m/s, rather than the 130 m/s listed on the KSP Δv map. I'm getting similarly inflated Δv's for every planet in the Kerbolar system. What on earth am I doing wrong? The initial formula I used, provided by Scott Manley in one of his tutorial videos, is v2 = GM(2 / r - 1 / a). For M, I'm using the mass of Kerbol; for r, the orbital radius of Kerbin; and for a, the semimajor axis between the orbital radii of Kerbin and Duna. Variations found on Wikipedia provide the same result as the initial formula.

Last week there was a thread created that discussed the basic requirements of deltaV required to get into various positions of the moon. Other than the launch variables the statement was made or asked if deltaV tables was the best way to handle this. I looked at the from an energy perspective, first off I need to add that the classic formula for calculating delta-V between two circular orbits is - SQRT(u/r0) for the first burn (r is r0 in this case in the wiki image, ignore the v = ) r can either be an apoapse or periapsis and SQRT(u/r1) - (r is r1 in this case in the wiki image) for the second burn. r can either be an periapsis or apoapse The perfect energy requirement equal to the is close to this at in the case of the lowest and highest eccentricities (e = 1) but in the middle ranges it is considerably different. The basic problem is that elevation of a circular orbit neccesarily requires two burns. During small burns the change of velocity is small and as a consequence little momentum is lost. In changing to very eccentric orbit much momentum is lost, but the dV required to establish the second orbit is small fractional to the energy required to create the transfer orbit. At minimum escape velocity its zero. In eccentricities (e) of transfer orbits around 0.7 (e.g a geosynchronoous from LEO transfer) have substantial inefficiency because considerable momentum is lost as the satellite slows to its apoapse at which it needs to burn. So for example a station keeping burn is perfectly efficient, and also a escape orbit (minimal) is perfectly efficient (but because of N-body problems more or less a theoretical exercise) The energy requirement works within tolerances if the correction factor for eccentricity is provided dV (total)/((1-e)+LN(1+e^1.9)), up to about e=0.75 but becomes inaccurate after this. Its not perfect. I tested this with a number of orbits, a is irrelevant the error is a function of e. This means without using a table one has a minimum requirement for a single step energy plot of knowing e as well as initial radius and final radius. Its not hard to calculate e but in creates also a two step operation. Ergo the OP is correct, the two step dV plots are as simple as any other means of plotting the dV requirements of an orbital change.

FYI found a very early access indy game on steam called Celestial Command, which is a space game which uses Newtonian orbital mechanics and the Unity engine, reminds me of early KSP quite a bit, though it is not the same kind of play, being top down 2D/3D. It is a resourcing / crafting / trading / pew 'em up game and looks like it is being built with multiplayer in mind though I have only tried single player so far. Gameplay is, like KSP, engaging for mechanical types. You mine asteroids/moons/planetismals in orbit to trade the ores, make fuel and also build your ship out of the same ores. The structure of the ship and thruster placement etc all matter for the flight physics as does mass distribution including cargo. Its very early days, so is cheap, thought some might enjoy. http://celestialcommand.com/ It occurred to me this game owes a lot to KSP and probably wouldnt even exist if KSP had not made it possible for gamers to engage with orbits and, in that sense, Squad would probably be justified in considering it a sincere form of flattery! Gameplay screeny to give some flavour. http://imgur.com/XldxJrZ

Can anyone recommend some good resources on the mathematics of orbital mechanics? I'm comfortable calculating Hohmann transfers (including alignment angle, dV budget, etc.), I can calculate dV for stages and total craft, but I'm having a hard time figuring it out past there. I'd love to be able to calculate the dV required for plane changes the new trajectory from a gravity assist the launch window for non-Hohmann transfers porkchop plots map out a spiral transfer for low thrust engines and plan re-entry trajectories. I expect some of these problems have known simple solutions, and some will require numerical integration. I'm comfortable setting up and solving either method. My background: I'm a chemical engineer. I'm comfortable solving ODEs (ordinary differential equations) and PDE (partial differential equations). I don't usually work in multi-dimensional calculus, but I do understand the basics of dot and cross products. There was a point in time in college where I was better with those. My trig is pretty good, but my calculus in cylindrical or polar coordinates isn't great. I usually use MathCAD for complex problem solving but don't have access to it right now. So I usually set up Eularian integrators in excel when I can't work out exact solutions. With a little work I could make it run Runge-Kutta instead. I've read the wikibooks articles on orbital mechanics, as well as these links http://hyperphysics.phy-astr.gsu.edu/hbase/kepler.html http://www.braeunig.us/space/orbmech.htm http://ocw.mit.edu/courses/aeronautics-and-astronautics/16-07-dynamics-fall-2009/lecture-notes/MIT16_07F09_Lec14.pdf http://www.bogan.ca/orbits/kepler/orbteqtn.html