Retrograde planets?

[More Boosters]

The amount of astrology-related stuff that came up when googling... Ugh.

This is probably not very likely considering the accretion disk the planets are formed in spins in one direction so they would have to be a captured body or something, but it would still present an interesting gameplay challenge with the relative velocities involved.

I mean we could at least have retrograde asteroids.

Edited September 11, 2015 by More Boosters

[KerikBalm]

Not a single example of a retrograde asteroid or comet is known.

We could have retrograde moons though.

We do have some aseteroids that enter the kerbin system in a retrograde direction (relative to Kerbin, not the Sun), and if you're not careful, you may capture them still going retrograde.

Any object in the solar system that was obiting retrograde to the sun, would be highly highly likely to have been an objct that was captured from interstellar space.

Asteroids are clearly not that.

Some comets from the edge of the Oort cloud.. maybe Eons ago a passing body disturbed some, and maybe some could get recaptured retrograde... but it seems unlikely.

Making Pol orbit Jool retrograde could be fun though.... or add another gas giant with a moon like Triton, and smaller moons that orbit the other way.

[More Boosters]

Not a single example of a retrograde asteroid or comet is known.

We could have retrograde moons though.

We do have some aseteroids that enter the kerbin system in a retrograde direction (relative to Kerbin, not the Sun), and if you're not careful, you may capture them still going retrograde.

Any object in the solar system that was obiting retrograde to the sun, would be highly highly likely to have been an objct that was captured from interstellar space.

Asteroids are clearly not that.

Some comets from the edge of the Oort cloud.. maybe Eons ago a passing body disturbed some, and maybe some could get recaptured retrograde... but it seems unlikely.

Making Pol orbit Jool retrograde could be fun though.... or add another gas giant with a moon like Triton, and smaller moons that orbit the other way.

I thought Halley's Comet was pretty well known.

And yeah, Jool has a lot of moons and Pol or Bop could certainly be far more interesting in a retrograde orbit!

Edit:

A quick googling gives me this.

Artifact in a binary system (would be cool to have in KSP as an option!), but possible nevertheless. Also a lot of ways for something to have been captured.

Edited September 11, 2015 by More Boosters

[kreutzkevic]

Not a single example of a retrograde asteroid or comet is known.

Minor planets with orbital inclinations greater than 90° orbit in a retrograde direction. As of July 2015 there are 64 known retrograde minor planets.

And Triton... (granted, not a comet nor asteroid)

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It would also be cool to have one planet spin clockwise in stead of the boring counter-clockwise fashion (eg. Venus). Ooohhh, and Trojan asteroids.

Edited September 11, 2015 by kreutzkevic

[More Boosters]

Minor planets with orbital inclinations greater than 90° orbit in a retrograde direction. As of July 2015 there are 64 known retrograde minor planets.

And Triton... (granted, not a comet nor asteroid)

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It would also be cool to have one planet spin clockwise in stead of the boring counter-clockwise fashion (eg. Venus). Ooohhh, and Trojan asteroids.

To be fair he did mention that we could have retrograde moons, a pretty good idea as he said would be to convert Bop or Pol to be retrograde.

[kreutzkevic]

Fair enough, and one of these seem like a likely candidate. Or Gilly. It would be awesome.

[More Boosters]

Fair enough, and one of these seem like a likely candidate. Or Gilly. It would be awesome.

Perhaps even Eve itself so not only you can't take off from it, you now can't aerobrake either.

In all seriousness I can see it working for Gilly; the dV to take off and land isn't much there anyway. Though I would still prefer Pol to go the other way first!

[kreutzkevic]

Or there's the unconsidered third option: 1.1 vastly improves memory management and this makes adding the second gas giant feasible. One of its moons could orbit retrograde...

We can but hope

[EladDv]

scientifically it's very rare. because of the way planets form from the remains of the material that created the main start they will always be within a close inclination to one another- i think that in our system the max deviation is 2 degrees (i might be wrong on that number but it's very low) this is because of the way that a 3d cloud momentum makes them coalesce into a (roughly) 2d disk of material. Now the only options of a retrograde planet is either a rouge planet getting caught in the gravity of the main star or a small planet getting some really powerful gravity assist.

[More Boosters]

scientifically it's very rare. because of the way planets form from the remains of the material that created the main start they will always be within a close inclination to one another- i think that in our system the max deviation is 2 degrees (i might be wrong on that number but it's very low) this is because of the way that a 3d cloud momentum makes them coalesce into a (roughly) 2d disk of material. Now the only options of a retrograde planet is either a rouge planet getting caught in the gravity of the main star or a small planet getting some really powerful gravity assist.

Highly inclined orbits for dwarf planets in the solar system are not unprecedented however. Retrograde is a stretch but not by that much.

[EladDv]

Highly inclined orbits for dwarf planets in the solar system are not unprecedented however. Retrograde is a stretch but not by that much.

those highly inclined orbits are not there at the start of the solar system. those are MOST chances caused from collisions with large objects(more common in the asteroid belt and kuiper belt) or large gravity assists from large object in their vicinity, but as when you are as far out as the oort cloud the momentum and collision rate are low enough to keep them in the shape of a sphere.

[p1t1o]

I think the coolest option would be a captured rogue planetoid, smallish, in a retrograde but highly inclined orbit - captured objects are unlikely to be exactly in the plane of rest of the planets. However improbable it is, it is plausible, and would represent a very unusual challenge.

I also like the idea of having a planet or moon rotate on its axis in the other direction, just to mix things up.

And what with all the talk of comets, howsabout having one (or a few) of those? Although Im sure simulating the coma/tail would be troublesome.

[kreutzkevic]

And what with all the talk of comets, howsabout having one (or a few) of those? Although Im sure simulating the coma/tail would be troublesome.

It has been done before:

But this eats memory and frame rate like nobody's business.

Edited September 11, 2015 by kreutzkevic

[More Boosters]

those highly inclined orbits are not there at the start of the solar system. those are MOST chances caused from collisions with large objects(more common in the asteroid belt and kuiper belt) or large gravity assists from large object in their vicinity, but as when you are as far out as the oort cloud the momentum and collision rate are low enough to keep them in the shape of a sphere.

Yes, they weren't, my point was that a retrograde orbit planet wouldn't need to form at the start to begin with. And you don't need to look as far as the Oort Cloud, I'm talking about Pluto, Eris, Makemake, Haumea. And yes, I realize how unlikely a 180 inclination planet is, my point was that regardless of the chances it is not implausible to the point it would invalidate the gains in gameplay variety.

I think the coolest option would be a captured rogue planetoid, smallish, in a retrograde but highly inclined orbit - captured objects are unlikely to be exactly in the plane of rest of the planets. However improbable it is, it is plausible, and would represent a very unusual challenge.

I also like the idea of having a planet or moon rotate on its axis in the other direction, just to mix things up.

And what with all the talk of comets, howsabout having one (or a few) of those? Although Im sure simulating the coma/tail would be troublesome.

I think KerikBalm wanted to put emphasis on his statement that there's no object in a retrograde orbit around the sun by mentioning comets but that is untrue as the most widely known comet, Halley's Comet, is itself in a retrograde orbit.

[EladDv]

Yes, they weren't, my point was that a retrograde orbit planet wouldn't need to form at the start to begin with. And you don't need to look as far as the Oort Cloud, I'm talking about Pluto, Eris, Makemake, Haumea. And yes, I realize how unlikely a 180 inclination planet is, my point was that regardless of the chances it is not implausible to the point it would invalidate the gains in gameplay variety.

i agree, retrograde planets would make for a good challenge in gameplay (but i would advise putting them instead of eeloo and make eeloo farther with a more eccentric orbit) but we need to watch out for the difficulty we want to have of reaching those planets- as their velocity would be 10-15 Km/s relative to kerbin. maybe retrograde moons are a better alternative for that sort of variety.

[cantab]

In real life all planets that formed orbiting their star are going to orbit in more or less the same plane and same direction. A retrograde planet must either be actually a sub-brown dwarf that formed by cloud collapse itself, or have been captured from another solar system.

As far as gameplay goes, a very distant object in a retrograde orbit requires little more delta-V than the same object in a prograde orbit. A small comet-like or asteroid-like planet in an appropriate orbit would make much more of a gameplay challenge.

I'd also like to see a real outer irregular moon for Jool. Jool's SOI is *huge* and even Pol is close to the planet and essentially a regular moon. A new Joolian moon way far out would add some new interest and gameplay challenges. You'd probably want to encounter it directly from your interplanetary trajectory where-ever it is on its orbit, and transferring between it and the inner moons could be lengthy if you minimise delta-V.

[More Boosters]

In real life all planets that formed orbiting their star are going to orbit in more or less the same plane and same direction. A retrograde planet must either be actually a sub-brown dwarf that formed by cloud collapse itself, or have been captured from another solar system.

As far as gameplay goes, a very distant object in a retrograde orbit requires little more delta-V than the same object in a prograde orbit. A small comet-like or asteroid-like planet in an appropriate orbit would make much more of a gameplay challenge.

I'd also like to see a real outer irregular moon for Jool. Jool's SOI is *huge* and even Pol is close to the planet and essentially a regular moon. A new Joolian moon way far out would add some new interest and gameplay challenges. You'd probably want to encounter it directly from your interplanetary trajectory where-ever it is on its orbit, and transferring between it and the inner moons could be lengthy if you minimise delta-V.

Well, yes, I would have it rather high up as otherwise it's going to be impossible to get to. Just imagine the like 30k delta-V you'd need to get to something around Moho but rotating the other way. The comparatively little DeltaV you mentioned is still roughly around 2k or more, not that much smaller than twice Eeloo's orbital speed, what's Eeloo's orbital speed again?

You're right about Jool but it's an expy of Jupiter whose major moons are also almost all on equatorial orbits. If we ever get that second gas giant I'm all for eccentric outer moons. Right now just reversing Pol's orbit should spice the place up enough.

[NecroBones]

Yep, I've wanted a retrograde moon for a long time, as an analogy to Triton.

As an aside, retrograde comets are quite possible. Long-period comets from the Oort Cloud region wouldn't need to be disturbed very much out at their Aphelions to get into some wacky orbits.

[sal_vager]

Thread moved to Suggestions and Development, with all the other "more planets" threads

[Joonatan1998]

Not a single example of a retrograde asteroid or comet is known.

It seems like there are even retrograde planets.

A few years ago at least one exoplanet was found on retrograde orbit:

https://www.google.fi/search?q=exoplanet+on+retrograde+orbit&ie=utf-8&oe=utf-8&gws_rd=cr&ei=3UXzVaGXNsLZU4z2l6gH

And there are lots of retrograde comets/asteroids:

https://en.wikipedia.org/wiki/List_of_exceptional_asteroids#Retrograde

Edited September 11, 2015 by Joonatan1998

[KerikBalm]

Huh.... I didn't realize Halley orbited in a retrograde orbit...

I suppose I could modify the statement to exclude those in veyr eccentric orbits.

I did at least realize comets were more likely to be retrograde:

Some comets from the edge of the Oort cloud.. maybe Eons ago a passing body disturbed some, and maybe some could get recaptured retrograde...

I just didn't realize that so many were

As to that list... I didn't see any on there that were asteroids... granted they don't specify what it is in most cases, its pretty obvious for many when they specify:

"Semi-major axis of 837AU,"

"Has a semi-major axis of 1254 AU,"

"This outer-planet crosser is a damocloid and SDO."

"A damocloid and SDO. Crosses all the outer planets except Neptune. Came within 0.03 AU of Ceres in 1930"

I didn't see any that seemed like they were likely to be asteroids.

As to exoplanets... my earlier statement was incomplete:

Any object in the solar system that was obiting retrograde to the sun, would be highly highly likely to have been an objct that was captured from interstellar space.

It could be something from interstellar space, or a very massive object from interstellar space could do funny things to the planets already there... but that would screw up all the other planets (in much the same way that Triton basically destroyed Neptune's original moon system)

The Kerbol system shows no signs of perturbation from a close encounter with another interstellar neighbor. I can't imagine how we could have a retrograde orbiting planet and still have the regular system of planetsthat we have.

[cantab]

Well the division between "comet" and "asteroid" is somewhat blurred anyway. But 2005 VD stands out, with an inclination of 172° and an orbit between the orbits of Jupiter and Saturn; while somewhat eccentric, it's not an extremely elongated orbit like a typical comet has.

[Joonatan1998]

So:

-Having a gas giant on retrograde orbit with a solar-system-like planetary system would be very unrealistic.

-a Kerbin-sized planet on retrograde orbit in the outer parts of the system could be possible, but extremely unlikely. (wouldn't be large enough to break the whole system.)

-Asteroids, comets can have almost any orbit.

I think objects with very elongated orbits don't work very well in ksp, their SOIs are tiny because the closest point in their orbit determines its size.

[KerikBalm]

Well the division between "comet" and "asteroid" is somewhat blurred anyway. But 2005 VD stands out, with an inclination of 172° and an orbit between the orbits of Jupiter and Saturn; while somewhat eccentric, it's not an extremely elongated orbit like a typical comet has.

Yea, that does seem to be more asteroid like, but its also classified as a damocloid.

https://en.wikipedia.org/wiki/Damocloid

"Damocloids are minor planets such as 5335 Damocles and 1996 PW that have Halley-family or long-period highly eccentric orbits typical of periodic comets such as Halley's Comet, but without showing a cometary coma or tail. David Jewitt defines a damocloid as an object with a Tisserand's parameter relative to Jupiter TJ ≤ 2."

"Damocloids are thought to be nuclei of Halley-type comets that have lost all their volatile materials due to outgassing and become dormant. Such comets probably originate from the Oort cloud. This hypothesis is strengthened by the fact that a number of objects thought to be damocloids (and assigned minor-planet provisional designations) subsequently showed a coma and were confirmed to be comets: C/2001 OG108 (LONEOS), C/2002 CE10 (LINEAR), C/2002 VQ94 (LINEAR), C/2004 HV60 (Spacewatch) and possibly others. Another strong indication of cometary origin is the fact that some damocloids have retrograde orbits, unlike any other minor planets. "

But it is also classified as a centaur:

"Centaurs are small Solar System bodies with a semi-major axis between those of the outer planets. They have unstable orbits that cross or have crossed the orbits of one or more of the giant planets, and have dynamic lifetimes of a few million years.[1] Centaurs typically behave with characteristics of both asteroids and comets."

So....

Well, if we are only speaking of objects with a SMA less than Jupiter's... then can we say there aren't any in retrograde orbits?

We also don't seem to have any example of a heliocentric retrograde orbit that is stable over long periods of time.

A retrograde moon would be cool,

I'd also like to see just more inclined orbits in general.

Bop and Pol really aren't all that bad.

Edited September 13, 2015 by KerikBalm

[The Aziz]

I may be wrong, and I probably am, but isn't it all about just getting to planet's/moon's SOI, in prograde direction (it is possible, right? Just timing must be perfect), then waste a lot fuel to break from freakin fly-by velocity. Right?