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A dwarf planet coming within 11 AU of the sun over the next 10 years

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Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#151

Post by megablast »

Fordec wrote: post #125
mcorning wrote: post #13

For reference 1 AU (Astronomical Unit) is about 150 million km. Saturn ranges from being about 7 to 11 AU away from Earth. Voyager 1 is 152 AU away. This object is excitingly close and will be fun to study.

Is it possible to get a probe out that far in time to make a good intercept? I imagine with this (relatively) short notice this is cutting it a bit close to orchestrate a proper orbital insertion by a designed, manufactured and tested program?

> Voyager 1 is 152 AU away

Hmmm, can we make 11au?? I think so.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#152

Post by Armisael16 »

shkkmo wrote: post #73
jessriedel wrote: post #53

Earlier quoted context omitted.

Yes, this is an aspect of orbital mechanics that people find unintuitive before they study it. You can't be captured by a planet's gravity alone. If you come in from infinity (i.e., not already captured) you will escape to infinity (remain not captured). The basic idea can be seen from the fact that gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit aro…

> You can't be captured by a planet's gravity alone Technically, this isn't completely true. There are gravity assist techniques that will allow you to dump speed by essentially adding your momentum to the object you are trying to orbit. The is basically an anti-slingshot manuever. In practice, I believe the range of scenarios when this is possible with a dwarf planet is so small as to be practically useless.

In a two-body system it doesn’t matter what you do; gravity is a conservative force so conservation of energy demand that you leave the body’s SoI at the same speed you entered it (in the body’s frame of reference).

You can lose speed or alter course relative to another body in a single encounter, and those changes can reduce speed in future encounters, but if you’re on an escape trajectory heading in you stay in one (without forces beside two-body gravity, which is a pretty safe assumption 11 AU out of Saturn doesn’t come close).

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#153

Post by joeyh »

mekkkkkk wrote: post #142
CapitalistCartr wrote: post #137

Earlier quoted context omitted.

There definitely are. A major reason for "demoting" Pluto was there are more such Pluto-scale planets in the Kuiper belt. Maybe we will find one bigger than Pluto.

Thanks! That's wild to me. All talk about exoplanets and other pop-sci headlines makes you think we would have our own backyard figured out. Then again, I suppose the vastness of space is vast even within our solar system.

Big backyard.. The Oort cloud extends a sizable fraction of the distance to Alpha Centari. No spacecraft has reached it and very little is known.

It's remarkable that this dwarf planet's orbit reaches it. Its aphelion is 54,600 AU, or 0.86 light years!

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#154

Post by garaetjjte »

perl4ever wrote: post #122
messe wrote: post #49

Earlier quoted context omitted.

Somewhat unintuitively, thanks to the Oberth effect, it can be easier to reach escape velocity closer to an object, (Humorously portrayed in https://xkcd.com/1242 ). Aside: if you are looking to learn more, I cannot recommend Kerbal Space Program enough.

I've been aware of people talking about Kerbal Space Program for years and years, but I lost interest in playing it when I heard it didn't do real N-body gravitational calculations because they were too intensive. I still find that inexplicable. To me, it sounds like saying "our calculator only does basic arithmetic on four core machines, square roots are too slow".

There's mod though! https://forum.kerbalspaceprogram.com/index.php?/topic/162200...

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#155

Post by himinlomax »

prince781 wrote: post #138
jessriedel wrote: post #53

Earlier quoted context omitted.

Yes, this is an aspect of orbital mechanics that people find unintuitive before they study it. You can't be captured by a planet's gravity alone. If you come in from infinity (i.e., not already captured) you will escape to infinity (remain not captured). The basic idea can be seen from the fact that gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit aro…

> gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit around a planet and spontaneously be ejected. I don't have a strong background in physics, and perhaps this is splitting hairs, but is this true if we consider gravitational radiation? Over a very long time a body's orbital energy will be lost to gravitational waves.

Over a very long time, we are all very dead. From what I understand, the loss in gravitational energy would be so tiny, the length of time required for it to eventually matter in any way would be way beyond the lifespan of the sun. So it's only a finite duration if you have infinite time, which you don't.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#156

Post by gifnamething »

tmhrtly wrote: post #57
jessriedel wrote: post #53

Earlier quoted context omitted.

Yes, this is an aspect of orbital mechanics that people find unintuitive before they study it. You can't be captured by a planet's gravity alone. If you come in from infinity (i.e., not already captured) you will escape to infinity (remain not captured). The basic idea can be seen from the fact that gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit aro…

What if we crash landed into it? That would probably tick the irreversible box. Clearly engineering difficulties quite high though!

That crash still needs to absorb the same amount of speed that was just defined as too much to expel in orbit

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#157

Post by gravypod »

megablast wrote: post #151
Fordec wrote: post #125

Earlier quoted context omitted.

Is it possible to get a probe out that far in time to make a good intercept? I imagine with this (relatively) short notice this is cutting it a bit close to orchestrate a proper orbital insertion by a designed, manufactured and tested program?

> Voyager 1 is 152 AU away Hmmm, can we make 11au?? I think so.

This is not a ridiculous question and does not deserve a mean answer.

Voyager 1 has been flying for over 43 years [0]. In that time it went over 150 AU. This averages about 3.5 AU/year. It took, from start of project to launch, about 5 years (1972 - 1977 [1]).

If this body is going to be 11 AU away in 10 years away we'd need to move at an average 2.2 AU/year and hit the right launch windows.

I think that it falls into the "yes, it's possible" but not into the "of course it's possible, how could you even ask" category.

[0] - https://en.wikipedia.org/wiki/Voyager_1

[1] - https://voyager.jpl.nasa.gov/mission/timeline/#event-voyager...

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#158

Post by II2II »

dylan604 wrote: post #145
Taek wrote: post #128

Earlier quoted context omitted.

For my purposes 10 AU has a lot more meaning than 1 billion km. 1 AU has a lot more context

It's one of those things that I still tilt my head slightly at when thinking about how the human brain struggles with really large numbers. Its just an odd thing.

In a case like this, I suspect it has more to do with visualizing the solar system rather than how large something is. When we speak in AU, we can create a mental model with the Sun, Earth, and other object since everything is normalized to the size of Earth's orbit. When we speak in kilometers, a bit of arithmetic has to be done before creating the model. Regardless of the units though, we aren't directly visualizing the distances since they will be outside the scope of human experience until we actively start traveling the solar system.

Edit: for clarity.

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#159

Post by mrandish »

Meerax wrote: post #23

Is this something we could plan and manage to launch an orbiter/lander to in time? Has anyone thought about the possibility of slapping something like a telescope on that and letting it beam back data and images from veryyyyy far out eventually?

> slapping something like a telescope on that and letting it beam back data and images from veryyyyy far out eventually?

While this object will eventually orbit pretty far away in a solar system context, I suspect that additional distance may not be vast enough to make a meaningful improvement in observations of targets at interstellar distances.

I'd love to learn if I'm incorrect but I've always assumed for interstellar observation, larger sensors and more sensors has better ROI than a more distant sensor, at least short of some substantial fraction of a light year. If we're going to dedicate a 100 ton Starship payload to interstellar observing I imagine going much farther out than the Moon's shadow may not be a good trade (eg fuel mass vs payload mass).

Re: A dwarf planet coming within 11 AU of the sun over the next 10 years

#160

Post by op00to »

megablast wrote: post #151
Fordec wrote: post #125

Earlier quoted context omitted.

Is it possible to get a probe out that far in time to make a good intercept? I imagine with this (relatively) short notice this is cutting it a bit close to orchestrate a proper orbital insertion by a designed, manufactured and tested program?

> Voyager 1 is 152 AU away Hmmm, can we make 11au?? I think so.

The question isn’t can we make 11au. That’s facile. Can we make 11au at the exact velocity, location, etc etc etc?
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