[HN Gopher] A dwarf planet coming within 11 AU of the sun over t...
___________________________________________________________________
A dwarf planet coming within 11 AU of the sun over the next 10
years
Author : MKais
Score : 608 points
Date : 2021-06-20 18:39 UTC (1 days ago)
(HTM) web link (groups.io)
(TXT) w3m dump (groups.io)
| AudreyDoka wrote:
| Pas mal mais je connais pas trop son role.
| ncmncm wrote:
| Cue, Avi Loeb insisting this is a follow-up to Uomuamua...
| Flow wrote:
| Could Hubble and/or James Webb Telescope see this object with any
| clarity or is it too near?
| sydthrowaway wrote:
| How is it possible to have an orbit without the sun at the
| center?
| ncmncm wrote:
| An elliptical orbit has, instead of a center, two foci, or
| focuses. In a very eccentric, or sharp and skinny, ellipse like
| this object's orbit, there is a focus very close to each pointy
| end. The sun is at one of these. (There is nothing at the
| other.) At the point of closest approach to the sun somewhere
| inside (the radius of) Saturn's orbit, it will be going twice
| as fast as Saturn, but at almost a right angle to it, swinging
| past the south pole of the sun, and will then shoot out to an
| immense distance, slowing all the way until it slows down
| enough to fall back in again for another go.
| jbverschoor wrote:
| Is that Nibiru?
| throwaway316943 wrote:
| Too small, maybe a generation ship on approach?
| optimalsolver wrote:
| We shall call it...Rama.
| pfdietz wrote:
| This is actually terrifying.
|
| That body is on a cometary orbit, and need not be stable long
| term. If it's chaotically pushed around by the major outer
| planets it might get sent into an orbit that gets into the inner
| solar system. And if something that size hit Earth, it would be
| game over for life here -- the impact would vaporize much or all
| of the oceans.
|
| Even an impact by something the size of comet Hale-Bopp would
| destroy all higher life on the planet.
|
| The chance of impacts like this may have been underestimated
| because of anthropic selection -- if any had occurred in the past
| (say) 1 billion years then we would not be here.
| mabbo wrote:
| It's expected orbit will take it around 54,600 AU from the Sun.
| The orbital period of something that far out is in the millions
| of years range.
|
| If it doesn't kill us this time, rest assured by the time it
| comes back we'll have done the job properly already.
| pfdietz wrote:
| I'm more referring to objects of this kind, not this specific
| object.
|
| Threats from supercomets are not a new concern:
| https://academic.oup.com/mnras/article/448/1/27/990672
|
| "A 100 km comet striking the Earth would carry ~1000 times
| the energy involved in the creation of the 150 km Chicxulub
| crater and would presumably remove the surface biosphere"
| perl4ever wrote:
| I think people have suggested the dinosaur killing asteroid
| may have caused global fires and rain of molten rock, so
| that scale might be sufficient as far as humans are
| concerned.
| matkoniecz wrote:
| https://www.youtube.com/watch?v=ankmTU89X_A - simulation
| of impact. Note scale - both size and time. Note rebound
| that briefly created one of largest peaks in Earths
| history. And curtain of ejecta.
|
| https://www.newyorker.com/magazine/2019/04/08/the-day-
| the-di... (note: popscience and old! let me know if any
| here got disproved or there is more up to date material)
|
| Within two minutes of slamming into Earth, the asteroid,
| which was at least six miles wide, had gouged a crater
| about eighteen miles deep and lofted twenty-five trillion
| metric tons of debris into the atmosphere. Picture the
| splash of a pebble falling into pond water, but on a
| planetary scale. When Earth's crust rebounded, a peak
| higher than Mt. Everest briefly rose up. The energy
| released was more than that of a billion Hiroshima bombs,
| but the blast looked nothing like a nuclear explosion,
| with its signature mushroom cloud. Instead, the initial
| blowout formed a "rooster tail," a gigantic jet of molten
| material, which exited the atmosphere, some of it fanning
| out over North America. Much of the material was several
| times hotter than the surface of the sun, and it set fire
| to everything within a thousand miles. In addition, an
| inverted cone of liquefied, superheated rock rose, spread
| outward as countless red-hot blobs of glass, called
| tektites, and blanketed the Western Hemisphere.
|
| Some of the ejecta escaped Earth's gravitational pull and
| went into irregular orbits around the sun. Over millions
| of years, bits of it found their way to other planets and
| moons in the solar system. Mars was eventually strewn
| with the debris--just as pieces of Mars, knocked aloft by
| ancient asteroid impacts, have been found on Earth. A
| 2013 study in the journal Astrobiology estimated that
| tens of thousands of pounds of impact rubble may have
| landed on Titan, a moon of Saturn, and on Europa and
| Callisto, which orbit Jupiter--three satellites that
| scientists believe may have promising habitats for life.
| Mathematical models indicate that at least some of this
| vagabond debris still harbored living microbes. The
| asteroid may have sown life throughout the solar system,
| even as it ravaged life on Earth.
|
| The asteroid was vaporized on impact. Its substance,
| mingling with vaporized Earth rock, formed a fiery plume,
| which reached halfway to the moon before collapsing in a
| pillar of incandescent dust. Computer models suggest that
| the atmosphere within fifteen hundred miles of ground
| zero became red hot from the debris storm, triggering
| gigantic forest fires. As the Earth rotated, the airborne
| material converged at the opposite side of the planet,
| where it fell and set fire to the entire Indian
| subcontinent. Measurements of the layer of ash and soot
| that eventually coated the Earth indicate that fires
| consumed about seventy per cent of the world's forests.
| Meanwhile, giant tsunamis resulting from the impact
| churned across the Gulf of Mexico, tearing up coastlines,
| sometimes peeling up hundreds of feet of rock, pushing
| debris inland and then sucking it back out into deep
| water, leaving jumbled deposits that oilmen sometimes
| encounter in the course of deep-sea drilling.
|
| The damage had only begun. Scientists still debate many
| of the details, which are derived from the computer
| models, and from field studies of the debris layer,
| knowledge of extinction rates, fossils and microfossils,
| and many other clues. But the over-all view is
| consistently grim. The dust and soot from the impact and
| the conflagrations prevented all sunlight from reaching
| the planet's surface for months. Photosynthesis all but
| stopped, killing most of the plant life, extinguishing
| the phytoplankton in the oceans, and causing the amount
| of oxygen in the atmosphere to plummet. After the fires
| died down, Earth plunged into a period of cold, perhaps
| even a deep freeze. Earth's two essential food chains, in
| the sea and on land, collapsed. About seventy-five per
| cent of all species went extinct. More than 99.9999 per
| cent of all living organisms on Earth died, and the
| carbon cycle came to a halt.
|
| Earth itself became toxic. When the asteroid struck, it
| vaporized layers of limestone, releasing into the
| atmosphere a trillion tons of carbon dioxide, ten billion
| tons of methane, and a billion tons of carbon monoxide;
| all three are powerful greenhouse gases. The impact also
| vaporized anhydrite rock, which blasted ten trillion tons
| of sulfur compounds aloft. The sulfur combined with water
| to form sulfuric acid, which then fell as an acid rain
| that may have been potent enough to strip the leaves from
| any surviving plants and to leach the nutrients from the
| soil.
|
| Today, the layer of debris, ash, and soot deposited by
| the asteroid strike is preserved in the Earth's sediment
| as a stripe of black about the thickness of a notebook.
| This is called the KT boundary, because it marks the
| dividing line between the Cretaceous period and the
| Tertiary period. (The Tertiary has been redefined as the
| Paleogene, but the term "KT" persists.) Mysteries abound
| above and below the KT layer. In the late Cretaceous,
| widespread volcanoes spewed vast quantities of gas and
| dust into the atmosphere, and the air contained far
| higher levels of carbon dioxide than the air that we
| breathe now. The climate was tropical, and the planet was
| perhaps entirely free of ice. Yet scientists know very
| little about the animals and plants that were living at
| the time, and as a result they have been searching for
| fossil deposits as close to the KT boundary as possible.
| slowmovintarget wrote:
| Seems more likely that what has happened before will happen
| again, which is to say that Jupiter or Saturn pull it apart
| into asteroids and perhaps new moons.
|
| Jupiter's orbit is roughly five AUs, and Saturn's orbit is at
| roughly ten, and in those regions, they have enormous influence
| on where stuff gets to go in the solar system.
| grawprog wrote:
| I've always figured there's no point in worrying about giant
| planet destroying meteors, if one comes and we can't stop it,
| well we're all fucked. What can ya do at that point? If it
| can't be stopped and it can't be changed...well I guess we had
| a decent ride...at least it'll probably look cool before we're
| all vaporized.
| whatshisface wrote:
| What if it can be stopped in theory, but only if humanity
| pulls together and gets something right for once?
| EamonnMR wrote:
| An object that side won't be dissuaded with any of the
| firepower available to us. We'd be better off trying to
| build bunkers or something.
| edgyquant wrote:
| Can we not attach rockets to it just to nudge enough to
| barely not hit it? I don't think anyone would suggest we
| "America fuck yeah" a meteor with firepower.
| elihu wrote:
| I think it's largely a matter of how much advance warning
| we have. If we discover an object hundreds of kilometers
| in diameter on an orbit that will intersect with Earth in
| 100 years, then we'll have a better opportunity to nudge
| it early on so it misses entirely or develop a big enough
| bomb to turn it into a pile of gravel and ice chips that
| will (mostly) miss the Earth.
|
| The biggest fusion bomb detonated on Earth was Tsar Bomba
| at 50 megatons, though the full yield is thought to have
| been more like 100 if the Russians hadn't deliberately
| nerfed it over radiation concerns.
|
| Is there a theoretical upper limit to the yield of fusion
| bombs? I assume no one is building them bigger simply
| because there's no realistic military use for such things
| that wouldn't be better served by smaller accurately
| targeted nuclear bombs. Tsar Bomba was detonated in 1961,
| and no one has seen fit to repeat the experiment, though
| I suppose one or more of the major nuclear powers may
| have a modern warhead with equivalent yield that they
| just haven't tested or announced to the world.
|
| Wikipedia is saying that there's thought to be a
| practical limit of around 6 megatons of yield per metric
| ton of bomb mass [1], and actual nuclear devices have
| achieved a little over 5, so I guess after some point
| there's not much reason to make a bigger bomb when you
| can just make two smaller ones.
|
| This scenario is starting to sound a bit like a long-
| running Factorio game where the goal is to launch a
| rocket once a minute. With, say, a one year lead time
| could the economies of Earth launch a starship-style
| rocket with a half-dozen or so Tsar Bomba sized warhead
| once per day indefinitely? I think so. Would it be enough
| to destroy a dwarf planet? Probably not, but maybe it
| could knock loose enough chunks to nudge it into a
| slightly different orbit.
|
| [1] https://en.wikipedia.org/wiki/Nuclear_weapon_yield
| grawprog wrote:
| Well, sure if it happens, i just meant in that whole
| inevitable no matter what doom scenario thing.
|
| I just mean, worrying about that or being scared is not
| really worth it. If it happens it happens. There's better
| things to dedicate that energy towards. Save the worrying
| about things like that for the people being paid to come up
| with solutions in the extremely rare chance this happens
| within any of ours, our children's or our grand children's
| lifetimes, after that I dunno, I'll probably be dead by
| then.
| dimator wrote:
| Then we're toast.
| Asraelite wrote:
| The post says "Incl. 95.46628 +/- 0.000052".
|
| Am I right to interpret this as meaning that the body has an
| extreme inclination, almost in polar orbit of the Sun? That would
| be pretty interesting; it would mean an orbit completely out of
| line with the rest of the Solar System.
| nwallin wrote:
| Yes.
|
| But it's not _that_ interesting or unusual. The Oort cloud
| doesn 't really obey the plane of the solar system the way the
| planets or Kuiper belt do. That's why it's called a 'cloud' and
| not a 'belt'.
| sam-2727 wrote:
| Certainly interesting, but not necessarily surprising. The Oort
| Cloud is roughly spherical so inclination would be expected to
| be isotropic overall. On average there will be less high
| inclination bodies (isotropic inclination has a pdf of sin(i))
| but they will still exist.
| koheripbal wrote:
| Yes. It is the perfect place to host a berserker.
|
| It has an orbital period of 3 million years, so it will be its
| first site of humanity.
| [deleted]
| PicassoCTs wrote:
| Will this disturb longterm orbiting bodies (with exotic orbits)
| and drive them into the inner system, without the guardians able
| to catch?
| NegativeLatency wrote:
| I don't think so, to a meaningful extent. There's already lots
| of stuff out in the Oort Cloud with orbits out of the regular
| planar disk.
| mekkkkkk wrote:
| I know very little about the subject, but does this mean that
| there are planet-sized objects in orbit around the sun of which
| we are unaware of?
| CapitalistCartr wrote:
| 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.
| mekkkkkk wrote:
| 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.
| joeyh wrote:
| 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!
| designium wrote:
| swap dwarf planet for a neutron star and you have "Dragon's Egg"
| story.
| epaulson wrote:
| I went looking for a visualization of this orbit, and I found
| this tweet:
|
| https://twitter.com/rappolee/status/1406414441663528966
| andy_ppp wrote:
| Okay so if this was a direct hit, what would happen!? Would it
| just be a non event for the sun or could we expect higher
| temperatures on Earth or worse?
| EdSchouten wrote:
| It's apparently pretty hard to hit the Sun:
|
| https://www.youtube.com/watch?v=LHvR1fRTW8g
|
| (Though that video mostly talks about small objects like
| rockets. Maybe it's a different story for dwarf planets?)
|
| That said... Keep in mind that this is about a dwarf planet
| orbiting the Sun. It's 11 AU out, so twice as far from the Sun
| as Jupiter is.
| hedshodd wrote:
| A direct hit with the sun? Maybe slightly higher temperatures
| if the "impact site" was facing us, but not for long because
| the sun is highly convective and each "longitudinal ring" on
| the sun rotates differentially, thus dissipating the effects of
| that impact very very quickly. A good chunk of it would also
| probably burn up before even reaching the Sun, but how much of
| it is hard to say.
|
| But keep in mind, it says "within 11 AU of the Sun", which is
| still beyond Saturn; Saturn's 9.5 AU away from the Sun, and
| Uranus is about 19 AU away from the Sun. So it's still pretty
| far away.
| tigerlily wrote:
| groups.io I had never come across before. Praised be Mark
| Fletcher!
| mcorning wrote:
| 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.
| chronogram wrote:
| How come our culture didn't base astronomical units around base
| 10 of our current units?
| detaro wrote:
| It's an old unit, so there wasn't a global standard yet, and
| it's exact value wasn't known for a long time, but it was
| still useful for ratios. E.g. if you observe the orbit time
| of another planet, you can tell its distance from the sun
| relative to the distance of Earth to Sun (1 astronomical
| unit) relatively accurately, even if you can't measure what
| it is in meters very well.
| Pelam wrote:
| I have more trouble with parsec. I have a rough idea of how
| big our galaxy is in light years and some idea about nearby
| stars. Age of the universe helps anchor things in billions
| of light years. Then suddenly something is measured in
| parsecs. Probably a similar thing for the experts.
| Taek wrote:
| For my purposes 10 AU has a lot more meaning than 1 billion
| km. 1 AU has a lot more context
| dylan604 wrote:
| 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.
| II2II wrote:
| 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.
| [deleted]
| nwallin wrote:
| Astronomers could reasonably well measure angles between
| objects in the night sky, and with some basic geometry, you
| can measure the _relative_ distances between objects
| reasonably accurately. For instance, if you have a triangle
| ABC, and you know the angle ABC is 45 degrees, and the angle
| ACB is also 45 degrees, you know that the distance AB will be
| sqrt(2) /2 times the distance BC. If you have dozens of other
| points you want to know about, you can calculate the
| distances relative to BC as well. But what if you haven't the
| foggiest idea how many toises long BC is? (this was well
| before the metric system; toises was the unit of choice for
| Cassini) You either give units of toises for, for instance,
| the size of the Mars orbit with error bars of +/- 80%, or you
| give the size of the Mars orbit in terms of multiples of BC
| with error bars of +/- 5%.
|
| Measuring the AU is fraught with errors of all sorts. For
| centuries it mostly consisted of exploiting tiny parallaxes
| on the Earth's surface between planetary bodies- for
| instance, Cassini and Richtie measured the parallax of Mars
| between Paris and French Guiana. But a small error propagates
| to a much, _much_ larger error in the final result than
| relative distances between planetary bodies in AU distances.
| If your measurement of the parallax of Mars is off by one
| arcminute, your measurement is totally useless, but if your
| measurement of the angle to Mars is off by one arcminute,
| your distance to Mars in AUs is off by a few percent.
|
| It wasn't until the 1960s when the JPL measured distances to
| Venus and Mars using radar that we were confident we had a
| good grasp on how long an AU was. But by that point, we had
| already measured the relative distances between the bodies in
| the solar system using the AU ruler relatively accurately for
| centuries.
| nitrogen wrote:
| Just because nobody has said it yet and it's often assumed
| knowledge, one AU is supposed to be roughly the distance from
| Earth to the sun.
| eb0la wrote:
| Stupid question:
|
| The Hubble photos we have from Saturn are a 7-8 AU range,
| right?
|
| Even more stupid question:
|
| Pointing the Hubble there is worth the effort? how many pixels
| wide would be a 200km diameter object at 11 AU?
| de6u99er wrote:
| Unfortunately Hubble has issues at the moment. There's a
| couple of HN submissions about that.
|
| --> https://hn.algolia.com/?dateRange=all&page=0&prefix=false
| &qu...
| autosharp wrote:
| > how many pixels wide would be a 200km diameter object at 11
| AU?
|
| Depends on zoom and resolution of the camera.
| c7DJTLrn wrote:
| That's terrifying, no? A whole planet (yes a dwarf one, but
| still a PLANET) is just rogue and will wander through the orbit
| of Sol as it pleases.
| TameAntelope wrote:
| > I would estimate at an albedo of 0.01-0.08 a diameter of
| 130-370 kilometers (nominally 160) which puts it on a similar
| scale, if not larger than, Sarabat's huge comet C/1729 P1,
| and almost undoubtedly the largest Oort Cloud object ever
| discovered- almost in dwarf planet territory!
|
| So a bit less dramatic but still really cool.
| mdorazio wrote:
| For reference, a nominal 160km diameter would put it around
| the same size as the 40th largest asteroid known. Huge for
| an object coming from the oort cloud, but not really huge
| in comparison to other rocky bodies in the solar system.
| Pxtl wrote:
| It's not a rogue planet, that implies Interstellar. This is
| an object with a very long orbit that takes it out to he Oort
| cloud but still - a permanent resident of the solar system.
|
| It's basically just an exceptionally large comet. It's not
| Melancholia.
| drcode wrote:
| Love that movie
| infradig wrote:
| It made me so nauseous I had to stagger out of the
| cinema.
| Pxtl wrote:
| It needs a sequel.
| grawprog wrote:
| So pretty much between Saturn and Uranus....
|
| Even as an adult that still always makes me chuckle. I can't
| help it.
| edgyquant wrote:
| It's pronounced your-uh-ness by pretty much everyone (or
| your-ah-noose if your going by the greek god and not the
| Latin copy/paste.)
| TameAntelope wrote:
| I prefer to call it the Georgium Sidus!
| SonnyTark wrote:
| in Arabic (and a bunch of other languages I'm sure) it's
| pronounced: Oranos, I don't understand why the U in Uranus
| is not pronounced like the U in Ultra.
| grishka wrote:
| In Russian it's simply "Ooran".
| project2501a wrote:
| Cuz in Greek (my mother language), we pronounce "Ouranos"
| as "Ouranos".
| Koshkin wrote:
| > _"Our_
|
| Good to know, I guess...
| jazzyjackson wrote:
| A shot in the dark but I think there's a lot of "ult"s in
| English but not many "ura"s
|
| Uranium and Urine
| grawprog wrote:
| Leave it to HN to explain grammar, some history and a bit
| of etymology in response to a childish joke comment.
|
| And, that's why this place is great.
| hn_throwaway_99 wrote:
| Hope I can contribute, because this is actually very
| interesting. According to this [1], the most common
| American pronunciation was closer to "Your anus" (accent
| on the A in anus) until 1986, when a space probe was
| flying by and news casters thought weeks of that would
| get too "giggly", so they deliberately started
| pronouncing it "Urine us" (accent on the first syllable).
|
| [1] https://www.dollarshaveclub.com/content/story/anus-
| urine-us-...
| grawprog wrote:
| Thank you. That was amusing to read and I never actually
| realized there was so much about the pronunciation, I've
| heard a few different ones. but I always took it for
| regional dialect differences not something done
| intentionally. I may have sounded sarcastic, but I was
| genuinely serious, I really do enjoy the interesting
| factoids spawned by sometimes the most innocuous comments
| on HN. HN really does have a lot of people knowledgeable
| about a huge range of things.
| throwawaaarrgh wrote:
| https://www.youtube.com/watch?v=SQTKGXmITZg
|
| This just sounds like "urine us". Potato, potato?
| sp332 wrote:
| https://www.gocomics.com/getfuzzy/2003/02/18
| retsibsi wrote:
| I think "pretty much everyone" is an exaggeration. Google's
| pronunciations (British and US) are both the 'anus' version
| -- though the British one has a secondary stress on the
| first syllable, rather than the schwa of the US version.
|
| Growing up in Australia, the British 'you-ray-n@s' (i.e.
| not quite 'your anus', but only because of the first vowel
| sound) is the pronunciation I was familiar with. Lately
| I've heard 'you-r@-n@s' fairly often, but not exclusively.
| op00to wrote:
| Nope. I say your-anus.
| edgyquant wrote:
| You might but that is an incorrect pronunciation and the
| only time I've heard that (other than from people who
| aren't into astronomy) was in elementary school and even
| then the teacher told us it was a common, but wrong,
| pronunciation.
| earthboundkid wrote:
| A thread of people discussing pronunciations without
| saying where they are from or using IPA is a pointless
| waste of time. You may as well be talking about what time
| it is by posting "well, it's _dark_ here!"
| edgyquant wrote:
| It doesn't really matter where you're from. If you
| pronounce Uranus as your-anus you are pronouncing it
| wrong.
| 252452d wrote:
| Not how language works dude.
| op00to wrote:
| Your-anus! Ahh! Take that!
| [deleted]
| retsibsi wrote:
| Location/accent is important, but sometimes we can get by
| without IPA. There will be some ambiguity, but often
| we're sufficiently familiar with each other's accents to
| interpret phonetic spellings as intended. (Though I do
| think the @ symbol is indispensable, because representing
| the schwa sound with 'uh' is just confusing.)
|
| edit: sorry, just realised I probably misread you (as
| saying we should say where we're from _and_ use IPA), in
| which case this comment is redundant.
| [deleted]
| lopuhin wrote:
| I don't think Saturn comes that close, should be 8 AU at best,
| given that perihelion is at 9 AU.
| mcorning wrote:
| https://www.universetoday.com/15311/how-far-is-saturn-
| from-e...
|
| > For the sake of simplicity, Saturn is 1.2 billion km,
| roughly 7 AU, from the Earth when the two are at their
| closest approach to one another. They are 1.67 billion km,
| around 11 AU, from each other when they are at their most
| distant. Saturn and Earth are the closest to each other when
| they are on the same side of the Sun and at similar points in
| their orbits. The are the most distant when on opposite sides
| of the Sun.
| Denvercoder9 wrote:
| _> Saturn is 1.2 billion km, roughly 7 AU_
|
| That's a unit conversion error. 1.2 billion / 150 million
| is 8, not 7.
| jakeinspace wrote:
| I believe the 1.2B km was referencing mean orbital
| distance from the sun, which would be 8 AU, and therefore
| 7 AU from earth on closest approach.
| Denvercoder9 wrote:
| No.
|
| Saturn's perihelion (closest distance to the Sun) is
| 1.35B km (9.0 AU), its aphelion (furthest distance) is
| 1.51B km (10.1 AU), and its mean distance is 1.43B km
| (9.6 AU).
|
| Thus, at closest approach Saturn is 8 AU from Earth
| (since Earth orbits at an almost-constant 1 AU from the
| Sun).
| jakeinspace wrote:
| After checking Wikipedia, you are correct.
| [deleted]
| Fordec wrote:
| 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?
| megablast wrote:
| > Voyager 1 is 152 AU away
|
| Hmmm, can we make 11au?? I think so.
| gravypod wrote:
| 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...
| op00to wrote:
| The question isn't can we make 11au. That's facile. Can we
| make 11au at the exact velocity, location, etc etc etc?
| sojuz151 wrote:
| Some context: It took Cassini-Huygens 7 years to reach saturn
| with two venus and one jupiter flyby. It took New Horizons 9
| years to reach pluton with jupiter flyby. With Inclination of
| 95.467deg and Argument of perihelion of 326.285deg flyby
| could happen near to Ecliptic but for getting to orbit one
| would need a nice gravity assist from jupiter.
| jerf wrote:
| Maybe this will motivate us to finally design and launch a
| probe that launches in two or more launches, all but one of
| which are fuel.
|
| All our normal expectations for probe arrival times and such
| are based on one-shot launches, straight out of Earth's
| gravity well into escape velocity in one shot. It's not like
| launching with fuel suddenly makes it a two-day trip or
| anything, but it can do quite a bit of shortening and allow
| for quite a lot more maneuvering.
|
| This is one of the next touchstones in space progress I've
| been looking for. A lot of previously impractical things
| become practical if we can routinely do multilaunches.
| ernst_mulder wrote:
| Before I read that it is actually orbiting our star I briefly
| thought "maybe they had an accident with a nuclear waste dump on
| the far side of their planet"
| 34679 wrote:
| >almost undoubtedly the largest Oort Cloud object ever
| discovered- almost in dwarf planet territory!
|
| Not a dwarf planet.
| ncmncm wrote:
| Thus, "almost".
|
| But big enough to be spherical. Or to eliminate multicellular
| life on Earth, if it hit us.
| djmips wrote:
| C'mon maybe a few multicellular lifeforms would survive. What
| about everyone's favorite tardigrade?
| 34679 wrote:
| The headline does not contain "almost".
| ptcrash wrote:
| Apologies if this is an obvious question but I'm not familiar
| with astronomy. Will this dwarf planet just pass through our
| solar system or is there a chance it will start to orbit our sun?
| clajiness wrote:
| > its orbit takes it from just beyond the orbit of Saturn (10.9
| AU) all the way out to the Oort Cloud
|
| It looks like it currently orbits the sun.
| perl4ever wrote:
| According to the link, the outgoing aphelion will be almost
| 40% more than the previous one, so I wouldn't assume it's
| going to orbit indefinitely.
| elihu wrote:
| That seems awfully weird. Is that something that things
| orbiting the sun normally do?
| perl4ever wrote:
| My intuition is that anything with a really eccentric
| orbit (10s to 10s of thousands of AU) has more of a
| chance of passing through many gravitational fields that
| change its orbit.
| elihu wrote:
| I suppose that makes sense... if something is in an orbit
| that's flattened down until it's only slightly off from
| being a straight line in and out, then any very slight
| perturbations could really affect how close it comes to
| the sun on the next pass.
|
| The sun moves too a little bit, due to the pull of the
| planets. Maybe it's enough to make a difference?
| ptcrash wrote:
| Ah, for some reason I read the original message as some new
| dwarf planet was outside our solar system and had a
| trajectory towards it. Thanks for the clarification.
| MereInterest wrote:
| For the most part, conservation of energy dictates that bodies
| in orbit will stay in orbit, and bodies transiting the system
| will exit it. Think of it like a ball rolling down a hill, then
| back up a hill of equal height. By rolling downhill, it gains
| enough velocity to make it back up the hill.
|
| There are exceptions, of course. An asteroid passing through an
| atmosphere may be slowed down by friction (aerobraking), and be
| captured in orbit. Passing near another orbiting body, the
| interloper can be sped up or slowed down (gravity assist). But
| both of those require getting pretty close to a planet, and
| space is really big (citation needed), so it's unlikely that it
| would be captured.
|
| Edit: Looks like I had the same misinterpretation, that it was
| a rogue planet rather than an Oort/Kuiper belt object.
| ordu wrote:
| If it manage to do a gravity assist maneuver around some
| existing planet, it might. Probability of such is very low, I
| believe. Moreover, I think if there was any chance, scientists
| already knew about it. If they keep silence, then no, there are
| no chances.
| marcosdumay wrote:
| It is from our solar system. It has just a very eccentric
| orbit, but it was always orbiting the Sun.
|
| But for interstellar objects, the answer is always "no". Unless
| it passes very close to some object that there's an orbital
| slingshot (or a collision, the odds of both are basically
| zero), interstellar objects always move away.
| samus wrote:
| According to TA it _is_ orbiting the sun. The closest point out
| will be at beyond Saturn 's orbit, the farthest will be 30-50k
| AU. Of course, there are some error bars on these numbers that
| I can't interpret, and given that it orbits that far out, its
| orbit might actually be influenced by neighboring stars as
| well.
| gshubert17 wrote:
| It amazes me that it last visited the "inner" solar system
| 2.75 million years ago. And after perturbations its next
| approach will be 4.5 million years from now. Its aphelion
| distance will be about 0.8 lightyear.
| [deleted]
| andy_ppp wrote:
| Suppose this, if there are advanced civilisations doing
| interstellar travel and there really is a 200km object that could
| hit Earth (I understand this is too far out), what would be the
| way to ask them for help?
| subroutine wrote:
| Shoot a rocket into outer-space with a bunch of full human
| genomes (sequencing data), a backup of the internet, and a
| readme.
|
| The probability of a starship being within 5 lightyears of
| earth is likely zero. If there is one, it's probably because
| it's already on its way here.
| andy_ppp wrote:
| Who is to say we aren't the product of such a disaster...
| subroutine wrote:
| What do you mean "product"? Like...
|
| https://en.wikipedia.org/wiki/Cretaceous%E2%80%93Paleogene_
| e...
| blocked_again wrote:
| This is under the assumption that advancee civilizations can
| travel only as fast as speed of light.
|
| There is also a possibility that there are advanced
| civilizations that jailbreaked the Universe/Reality and can
| be anywhere in seconds. Whether they give a shit about
| primitive civilizations like us who invented decent computers
| only like fifty years back is a different question
| altogether.
| csomar wrote:
| They'd be already here, though. Or at least, evidence of
| them being here. If the universe is infinite, all possible
| advanced civilization should be already here. If time/space
| travel was possible, I think we should have seen it or
| evidence of it.
| andy_ppp wrote:
| Wormholes are great for that, the issue would be getting a
| signal to reach anyone useful in time. We need to find out
| how subspace radio works...
| subroutine wrote:
| Agreed. But are we assuming that breaking c means they are
| timetravelers?
| napolux wrote:
| pray
| nealabq wrote:
| For now they're calling it 2014 UN271. It's got a Wikipedia page:
| https://en.wikipedia.org/wiki/2014_UN271
|
| I suppose it'll get named soon.
| kpozin wrote:
| Note that dwarf planet Ceres, which orbits the sun at ~3 AU, is
| larger ([?] = 939 km) than this one ([?] = 100-200 km). There are
| ~25 other known asteroids with diameters over 200 km in the
| asteroid belt (https://en.wikipedia.org/wiki/List_of_exceptional_
| asteroids#...).
| zksmk wrote:
| Right, but it's not the size that counts, it's the motion in
| the ocean. And what's on the inside. This little guy's from the
| Oort cloud. He's been places, he's seen things.
| koheripbal wrote:
| Right, but the composition is likely very very different.
| bencollier49 wrote:
| If this is coming within range of the Oort cloud, ought we to be
| worried about being showered with perturbed meteors?
| kumarvvr wrote:
| Ok. I got really excited by the title. But the diameter of the
| planet is about 130 km, so its tiny.
|
| Maybe "fat asteroid" is a better term than "dwarf planet" ?
| yummybear wrote:
| I don't think we should be shaming asteroids in this way - how
| about "gravitationally challenged"?
| kumarvvr wrote:
| Sure.
|
| In that vein, "differently sized" should also be ok.
| ceejayoz wrote:
| > could possibly reach magnitude 13 in early 2031
|
| Don't get too excited about looking at this one; that's a bit
| brighter than Pluto, so you'd need a pretty decent telescope to
| spot it.
| https://en.wikipedia.org/wiki/Magnitude_(astronomy)#Examples
| Sharlin wrote:
| I believe this is _absolute_ magnitude, and specifically,
| absolute magnitude as defined for comets [1]. At Saturn 's
| distance, definitely not a naked-eye object in any case.
|
| [1]
| https://en.wikipedia.org/wiki/Absolute_magnitude#Cometary_ma...
| perihelions wrote:
| Not in this case: the +13 figure is a predicted *apparent*
| magnitude. The absolute magnitude 'H' as your link defines is
| the 'H' field in the OP link, which is +7.8. (Note that's 'H'
| from your link's section on asteroid magnitudes, not comets
| or stars -- they're all on different scales).
|
| Here's the documentation for the fields in OP's data table:
|
| "H Absolute visual magnitude. A table converting H to a
| diameter is available."
|
| https://www.minorplanetcenter.net/iau/info/OrbElsExplanation.
| ..
| Sharlin wrote:
| Ah, thanks. So its _H_ _asteroid is currently +7.8, and
| if/when it develops a coma it should become a lot brighter,
| but unfortunately even at perihelion still way too faint
| for a naked eye.
| [deleted]
| pavel_lishin wrote:
| Aw, I thought this was going to be an extrasolar object, but it's
| an oort object orbiting the sun.
|
| It's also pretty small, about 1/20th the size of the moon. Huge
| for a comet, but smaller than Ceres.
| sam-2727 wrote:
| It can definitely feel not as cool from a popular science
| perspective but there are many unanswered questions about the
| Oort Cloud so study of this object would be scientifically
| invaluable, even if it doesn't yield any "pop-sci" results.
| Meerax wrote:
| 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?
| c3534l wrote:
| Apparently no one likes this idea. Here's mine: we nuke the
| planet and collect its smitherines for SCIENCE!
| dancemethis wrote:
| A variation of this worked well for Final Fantasy XIV.
| 015a wrote:
| Let's send some boosters out there, redirect it to earth, and
| make a second moon. Come on people, what ever happened to
| doing shit cause its fuckin' rad, do you know how cool
| another moon would be?!
| f6v wrote:
| Let's just blow the moon up and give rise to 7 new
| genetically engineered races, man-fishes, and dwarves.
| beckingz wrote:
| If it worked in SevenEves I don't see why not?
| [deleted]
| Koshkin wrote:
| Bringing a large celestial body close to Earth would be
| just as smart as trying to let the aliens know that we are
| here. (The humanity may not be able to survive either one.)
| hirundo wrote:
| Constructive interference from multiple tidal waves could
| flood huge coastal areas, killing or displacing millions.
| Uncool.
| jazzyjackson wrote:
| Put it in orbit at a 90 degree angle from the moon with
| Earth as the center and you can cause destructive
| interference and lower the tides :)
| dylan604 wrote:
| Or very cool if you're an evil villain in a movie/comic.
| Give me one milllllion dollars, or I will bring in a
| second moon!
| 015a wrote:
| Then again, global warming is going to flood huge coastal
| areas, killing or displacing millions, which is a pretty
| uncool thing we're doing to ourselves, so maybe Second
| Moon will counter-act that? There's literally no way of
| knowing until we try. And worst case scenario, we ruin a
| bunch of earth and we've got a second moon to move to.
| Its a win-win.
| jessriedel wrote:
| If you launch your telescope on a spacecraft and get it to
| match speed with the dwarf planet (which is necessary for a
| soft landing), there's not much point in actually attaching it
| to the dwarf planet. That just blocks the view of half the sky.
|
| Also, there will be nothing to see out there other than the
| dwarf planet itself.
| vmception wrote:
| and frozen aliens
| seaman1921 wrote:
| perhaps the sun's heat exposes them :)
| egman_ekki wrote:
| ...that must be the delivery of ufoporno I ordered in
| good'ol devonian times :)
| tonmoy wrote:
| Is that really true? If we manage to get a spacecraft get
| captured by the dwarf planet's gravity and orbit it, would
| that not be a lot less delta-V compared to if we made the
| spacecraft achieve the dwarf planet's orbit around the sun
| just by itself?
| jessriedel wrote:
| 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 around a planet and spontaneously
| be ejected.
|
| Now, something like this can work if you use an
| _irreversible_ interaction like aerobreaking, but this
| dwarf planet has negligible atmosphere. You could also use
| the dwarf planet for a gravitational assist (basically
| bouncing off it like a billiard ball), but I think
| gravitational assists from the other planets are almost
| always more convenient and effective.
| CamperBob2 wrote:
| That's pretty cool. It's wildly counterintuitive, but if
| it weren't the case, the planets would be orbited by lots
| of captured asteroids and debris, instead of/in addition
| to being covered in craters. The only explanation for why
| that doesn't happen is that it _can 't_ happen.
| shkkmo wrote:
| The presence of natural satellites indicates this can
| indeed happen. It just requires a pretty unlikely orbital
| configuration.
| dragonwriter wrote:
| > The presence of natural satellites indicates this can
| indeed happen
|
| No, it doesn't, because natural satellites are generally
| not captured, and for those that are captured, the
| process involves interactions with other bodies.
| perl4ever wrote:
| The first hit when I search "planets capturing moons"
| says natural satellites generally _are_ captured.
|
| "Most satellites of the outer solar system didn't form
| with their host planets"
|
| https://astronomy.com/news/2016/12/captured-moons-of-the-
| gia...
|
| Even Triton, which is the size of a planet and in an
| almost circular orbit, is thought to be captured, the
| last I heard.
| CamperBob2 wrote:
| One of the criteria for planethood is an assumption that
| the body clears its own orbit. Moons don't just come
| hurtling out of the cosmos; they either result from a
| collision of some other body with the planet, as with our
| Moon, or they're already close to the planet's orbit at
| the time they are captured.
| perl4ever wrote:
| >One of the criteria for planethood is an assumption that
| the body clears its own orbit.
|
| Is that so?
|
| "The generic definition of a centaur is a small body that
| orbits the Sun between Jupiter and Neptune and crosses
| the orbits of one or more of the giant planets"
|
| https://en.wikipedia.org/wiki/Centaur_(small_Solar_System
| _bo...
|
| There are tens of thousands, so perhaps the definition of
| a planet is even more abstruse than people let on.
|
| And apparently at least dozens have been identified as
| probably of interstellar origin, while it is thought that
| a centaur can become a moon, (e.g. Phoebe) so I wonder if
| we can really rule out that moons "come hurtling out of
| the cosmos":
|
| "Being able to tell apart interstellar asteroids from
| native asteroids born in the Solar System has long eluded
| astronomers, but the team's results identified 19
| asteroids of interstellar origin. These are currently
| orbiting as part of the group of asteroids known as
| Centaurs, which roam the space in between the giant
| planets of the Solar System."
|
| https://ras.ac.uk/news-and-press/research-
| highlights/interst...
| shkkmo wrote:
| > Is that so?
|
| Yes, it is. The definition of "clearing an orbit" isn't
| precisely defined, but it doesn't have to be since there
| appears to be a large natural gap in how much orbit
| clearing an planet does vs. a dward planet.
|
| > A large body that meets the other criteria for a planet
| but has not cleared its neighbourhood is classified as a
| dwarf planet. That includes Pluto, whose orbit intersects
| with Neptune's orbit and shares its orbital neighbourhood
| with many Kuiper belt objects. The IAU's definition does
| not attach specific numbers or equations to this term,
| but all IAU-recognised planets have cleared their
| neighbourhoods to a much greater extent (by orders of
| magnitude) than any dwarf planet or candidate for dwarf
| planet.[0]
|
| [0] https://en.m.wikipedia.org/wiki/Clearing_the_neighbou
| rhood
| hinkley wrote:
| Jupiter's moons are I'm harmonic orbits because they
| trade momentum until they balance out.
|
| From what I understand any eccentric orbits would either
| flatten out or crash into Jupiter.
| CamperBob2 wrote:
| No, it doesn't. No (rocky) planet has more satellites
| than craters, but every planet's gravitational field is
| larger than its surface.
| 8note wrote:
| Do we know how many of those craters used to be
| satellites?
| stickfigure wrote:
| Or an impact:
|
| https://en.wikipedia.org/wiki/Giant-impact_hypothesis
| [deleted]
| azernik wrote:
| It can _reduce_ the delta-V requirements, though - by the
| same principles as a gravity assist, a capture burn
| (especially into a loosely-bound planet-centric orbit)
| often takes less work than burning into the equivalent
| heliocentric orbit on your own.
| JumpCrisscross wrote:
| > _by the same principles as a gravity assist, a capture
| burn_
|
| Note to the audience: these mechanisms don't violate the
| conservation of energy because you aren't tapping the
| object's gravitational energy _per se_ but instead its
| orbital energy around the sun. Put another way, you can't
| do a gravity assist or capture burn in any direction.
| azernik wrote:
| The usual way I explain it is as a transfer of kinetic
| energy and momentum from the large body to the small one.
| The interaction is through gravity, rather than the mix
| of electrostatic, degeneracy, and strong/weak forces
| involved in collisions; but the equations are more or
| less the same.
|
| (Usually textbooks use a baseball bouncing off a semi
| truck to illustrate.)
| beckingz wrote:
| Right! The Oberth effect for a smaller body is not as
| large as it would be for earth, but would still be non-
| zero.
| lmilcin wrote:
| "Non-zero" is the key word here.
|
| Oberth effect from fast flyby of a body with low gravity
| would be negligible.
| a1369209993 wrote:
| > Oberth effect from fast flyby of a body with low
| gravity would be negligible.
|
| Pretty sure the problem would be, rather, that a flyby of
| a body with low gravity would be negligibly fast
| (relative to your speed when not flying by). Oberth
| effect is _because of_ high speed (a given increase in
| momentum gives more kinetic energy at higher speed than
| at lower speed) - it 's just that dipping deep into a
| gravity well is the obvious way to _get_ that speed.
| jessriedel wrote:
| Ok, good point. Thanks.
| azernik wrote:
| Still definitely not worth it for something so small,
| though!
| shkkmo wrote:
| > 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.
| Armisael16 wrote:
| 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).
| shkkmo wrote:
| > In a two-body system it doesn't matter what you do;
|
| Two-body systems do not exist in reality.
|
| Energy is also conserved in 3 body problems. When you
| utilize the slingshot effect, some of the energy of the
| orbit of the body you are swinging around orbiting is
| transfered to you. The transfer of this energy does not
| depend on the closeness of the sun, but rather on how
| deeply you descend into the gravity well of the object
| you are slingshotting around.
|
| > which is a pretty safe assumption 11 AU out of Saturn
| doesn't come close
|
| No, it really isn't. The "safeness" of the assumption
| entirely depends on your margin for error. The existence
| of the naturally captured saturnian satellites clearly
| indicates that you are simply wrong about the relevant
| margins for error.
| lxmorj wrote:
| Saturn's captured satellites might also be the result of
| incidental aerobraking or whatever you want to call
| smashing into a bunch of very tiny satellites during a
| close periapsis, no?
| shkkmo wrote:
| You need some sort of subsequent acceleration to raise
| the perigree out of the atmosphere so the orbit doesn't
| continue to decay. This could happen due to a slingshot
| effect, but atmospheric braking alone is not enough to
| allow you to establish a stable orbit.
| tmhrtly wrote:
| What if we crash landed into it? That would probably tick
| the irreversible box. Clearly engineering difficulties
| quite high though!
| ehsanu1 wrote:
| It's a cool idea, but seems super sci-fi. Might need some
| wonder materials to make it feasible, even then that
| would be a really big crumple zone. Or flubber. Another
| crazy idea: latch on to the planet from the side, like a
| skateboarder hitching a ride by hanging on to a truck.
| Again, wonder materials required.
| azernik wrote:
| NASA and the Soviets didn't need any wonder materials,
| just airbags. (Though they did a lot of braking first -
| either with the atmosphere for NASA at Mars, or with
| thrusters for the Soviets at the Moon.)
| gifnamething wrote:
| That crash still needs to absorb the same amount of speed
| that was just defined as too much to expel in orbit
| Sharlin wrote:
| This is often jocularly called _lithobraking_ and is
| typically not advisable.
| fouronnes3 wrote:
| > not advisable
|
| Unless you're NASA landing a probe on Mars in 1997.
| Sharlin wrote:
| Seriously, the tandem failures of the Mars Polar Lander
| and Mars Climate Observer missions were probably
| something NASA as an organization needed at the time. A
| reminder that Space Is Hard, and you can only pick two of
| "faster", "better", and "cheaper". Since then, NASA's
| Mars program has grown in both scope and ambition, yet
| remarkably has had zero loss-of-mission failures during
| that whole time!
| fouronnes3 wrote:
| I was referring to the successful landing of Pathfinder
| but yeah... Space is Hard and NASA is good at it are both
| very true.
| phkahler wrote:
| After Pathfinder someone from NASA wrote a book about
| their new "faster, better, cheaper" approach to missions.
| Usually you can't have all 3 but they managed to get
| lucky. That made it particularly amusing when the book
| and concept were getting popular as the next 2 missions
| were failing.
| Sharlin wrote:
| Ah, yeah, you could call airbags lithobraking. I thought
| you referred ironically to the Mars Polar Lander, but it
| of course flew in the 1999 launch window rather than
| 1997.
| garmaine wrote:
| Most of the velocity of Pathfinder was shed using
| aerobraking and parachutes. The crash-balloon landing
| system just shed the last tiny sliver of velocity after
| cutting the chutes.
| Cthulhu_ wrote:
| Didn't they launch a projectile into an asteroid not long
| ago as well?
| [deleted]
| prince781 wrote:
| > 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.
| lmilcin wrote:
| It would be like saying all the school children exercises
| and train timetables are invalid because they don't take
| into account relativistic effects that _obviously_ are
| still present at 60mph.
| a1369209993 wrote:
| Technically? Yes! Incoming gravitational radiation of
| precisely the correct shape will in fact un-decay a orbit
| under exactly the same (modulo appropiate symmetries)
| circumstances as a orbit would decay by emitting (the
| reverse of) that radiation. (The same applies to thermal
| radiation cooling things off - see Liouville's Theorem.)
|
| For practical purposes, that'll never happen, but for
| practical purposes gravitation radiation doesn't matter
| anyway.
| himinlomax wrote:
| 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.
| isoprophlex wrote:
| It's a dwarf planet of ~ 200 km diameter. The thing has a
| miniscule gravity well, it won't matter much compared to
| launching from earth and matching orbits with it, i
| think...
| azernik wrote:
| For comparison, that's about 10% of the Moon's diameter,
| i.e. 0.1% of its volume. (The mass ratios are probably
| within that 0.1% ballpark, but can't tell for sure until
| we know more about its composition.)
| [deleted]
| eb0la wrote:
| IMHO beign able to spot something with this size at this
| distance is really awesome.
| azernik wrote:
| Interestingly, the images came from the Dark Energy
| Survey [1], which for entirely different different
| reasons is running a very sensitive and high-resolution
| scan of the sky in visible and near-infrared. This just
| happened to show up in a frame where they were looking
| for distant galaxies and events, and the Minor Planets
| Center noticed the thing.
|
| [1] https://en.wikipedia.org/wiki/Dark_Energy_Survey
| Teever wrote:
| > there's not much point in actually attaching it to the
| dwarf planet.
|
| I've been thinking that attaching a sabatier reactor to a
| probe and sending it to land on an extra solar body such as
| Oumuamua that contains the ingredients that the sabatier
| needs to produce fuel would be a great way to get a probe
| that sends signals back to Earth well after a nuclear battery
| has died.
| anfilt wrote:
| Like till it gets closer we dont even know if it would be
| suitable to put something like that on it.
|
| Although it does seem like interesting idea.
|
| However, we have sent probes much further than this object (aka
| the voyager missions).
|
| So it would mainly be useful for studying this object. So a
| telescope would be less than ideal since we could always in
| theory deploy a telescope much deeper into space if we wanted.
| floatrock wrote:
| Interestingly, the voyager missions were also timed-events --
| they were launched when they were because JPL realized it was
| a 1-in-175-year alignment of the outer planets that made it
| feasible to launch just a few crafts to visit the outer
| planets all in one go:
| https://en.wikipedia.org/wiki/Grand_Tour_program
| f6v wrote:
| AFAIK many launches are timed to make the flight shorter.
| Although not on 1 in 175 years, but shorter windows.
| bewaretheirs wrote:
| Just launch a deep-space telescope; it would be easier.
|
| Soft-landing the telescope on an airless body would be harder
| (in delta-V terms) than just launching it into an equivalent
| solar orbit. And the body would block about half your view of
| the sky at any one time.
| jbay808 wrote:
| Could you get a nice gravity boost away from the sun by just
| following it for as long as possible?
| _Microft wrote:
| The easiest way to think about this is as perfectly elastic
| collision between the spacecraft and the planet (mediated
| by gravity, but this is an unnecessary detail already).
| jstanley wrote:
| I think the point is that in order to follow it, you need
| to (at some point in time) be at the same place and with
| the same velocity. Then you'll follow it.
|
| But the energy required to do that is almost the same as
| what it would be if the dwarf planet wasn't there. You
| could get onto exactly the same orbit for roughly the same
| amount of energy, and if you relax the requirement that
| there be a dwarf planet nearby, you can choose superior
| orbits.
| lamontcg wrote:
| No, that's not how gravity boosts work. If you match speeds
| with an object you actually get zero boost.
|
| The point of a gravity boost is to come in pretty hot
| (relative to the body you're boosting off of) and then go
| out pretty hot in a different direction. So you take your
| relative velocity vector at the point of the encounter and
| twist it around. By doing that you change your orbital
| energy around your central body (the sun) by a lot, and the
| other object will lose a similar amount to keep the
| bookkeeping equal.
|
| If you have zero relative velocity compared to the thing
| you want a gravity assist off of you can't get an assist.
| It isn't like drafting a semi.
| geenew wrote:
| Could there be some energy advantage to being in orbit
| around it? I'm thinking of a scenario where you spend a
| large amount of energy once get into orbit around the
| object, but then gain a small amount of energy
| continuously through something like tidal forces.
| lamontcg wrote:
| Everything else is going to be small and average out over
| time. And if you manage to pick up a bit of energy
| orbiting a tiny object you'll quickly just get ejected at
| its (small) escape velocity. Whatever that gives you, it
| won't be worth the cost of matching orbits to start with.
| Better to come in hot and slingshot.
|
| Solar wind / radiation pressure is probably the next best
| free ride since that adds up over time continuously and
| is everywhere.
| 0-_-0 wrote:
| I think it should provide a much stronger slingshot
| velocity boost than any other planet, however getting to
| 11AU first is not easy.
|
| https://en.wikipedia.org/wiki/Gravity_assist
| btilly wrote:
| For the best gravity assist you want to have a large
| delta V, and you want to come in on a hyperbolic orbit
| that causes you to turn by 90 degrees.
|
| This object has all of the delta V that you could want,
| but for an object of that mass, the hyperbolic orbit
| would require going through the planetoid which you can't
| do. And if it was dense enough that you could (for
| example a miniature black hole), the tidal forces during
| the turn would be insane.
|
| So no, this object cannot give a decent slingshot.
| simonh wrote:
| The magnitude of the slingshot boost increases with the
| mass of the planetary body. This thing is smaller than
| any of the planets so you'd get a much smaller boost. The
| best planet for slingshotting from is Jupiter because
| it's the most massive.
| mikeytown2 wrote:
| Landing a telescope on it would only make sense if orbits
| around it are highly unstable (like our moon) and if the dwarf
| planet was geothermally active so energy on the surface would
| be "easy" to extract (which comes with it's own set of
| headaches). Orbiting it with a "big for space probes" camera
| would most likely give us more interesting data.
|
| Using the plant as a Coronagraph if orbiting far out is another
| interesting idea, but using a near earth astroid would be a
| better idea as the telescope could be powered by solar panels
| they.
| mrandish wrote:
| > 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).
| elihu wrote:
| It's probably more interesting to study the object itself.
|
| I assume its orbital period is long enough that it won't be
| back near the central solar system for a very long time. But
| similar objects could have interesting uses.
|
| One thought experiment is to consider what it would take to be
| able to live on such an object, perhaps even a rogue planet
| just floating between the stars.
|
| It would be very cold. Presumably you'd be reliant on nuclear
| fission or fusion for power, so you'd need a significant fuel
| supply that could effectively last indefinitely. And you'd want
| to have a ready supply of all the basic elements you need.
| Which seems more realistic the bigger the object is. Like, an
| Earth or Mars-sized rogue planet might be ideal.
| z3t4 wrote:
| Too far out from the sun and it wouldn't be able to re-charge
| using solar panels. Could put some kind of nuclear power plant
| on it though. And as others has pointed out, you would need to
| match the speed, so you could just as well use that power plus
| gravity assists to get far out. Landing on such a body would be
| really interesting though.
| ianai wrote:
| Probably the reason to orbit such a planet would be to help
| comms from a ground station on it.
|
| 11 AU though seems like quite the stretch right now but maybe
| if there were a fleet of Spacex Starships in operation...
| uCantCauseUCant wrote:
| It is a great opportunity for a interstellar slingshot though..
| residualmind wrote:
| While scientifically-minded folks are excited for a new object of
| study, or simply something awesome in the night sky - I _can 't
| wait_ until I see the first doomsday predictions by people with a
| different mindset... In a way it is also an object of study for
| those world views ;)
| Rerarom wrote:
| First read this as "dwarf star" and was really excited
| PaulHoule wrote:
| I think it is not so exceptional, it is just this is one of the
| first ones we spotted.
|
| Practically "outer solar system objects" and "interstellar
| objects" are overlapping categories since there is transport
| between the two.
| phy6 wrote:
| Meme stock apes have claimed this as the new destination of their
| portfolios.
| MKais wrote:
| How fast can we build and launch something to rendezvous with
| this dwarf planet?
| jessriedel wrote:
| New Horizons took a nearly straight shot to Pluto (just
| stopping by Jupiter on the way for a gravity assist). That trip
| took 9 years to travel 40 AU (not at constant speed, of
| courses, since it's constantly being drawn toward the Sun).
| This dwarf planet makes its closest approach at 10 AU, so you
| could do a fly by in less than 3 years if you wanted to pay for
| it. However, the science return from a flyby would be limited
| compared to falling into orbit around it.
|
| Rosetta took 10 years to match pace with and orbit a comet
| (which had a closest approach to the Sun less than 1 AU) using
| a number of gravity assists.
|
| https://raminskibba.net/2014/08/17/rosetta-and-the-comet/amp...
|
| https://raminskibba.files.wordpress.com/2014/08/f4-large.jpg...
| yummybear wrote:
| I would assume planning and budgeting would also take up a
| lot of time.
| messe wrote:
| Getting into orbit would be rather difficult, as the probe
| would have have to match the planets velocity at perihelion.
| My instinct says it's probably just on the edge of doable
| (although I'm not sure on which side), but I haven't crunched
| the numbers. It would almost certainly need to be launched on
| a Delta-IV or Falcon Heavy class vehicle.
|
| EDIT: s/perigee/perihelion. I could say periapse and be
| neutral, but perihelion sounds cool.
| jessriedel wrote:
| The speed of Rosetta's comet at perigee is, I think,
| significantly grater than the max speed of this dwarf
| planet. The dwarf planet has a much higher apogee, of
| course, but escape velocity, corresponding to infinite
| apogee, is finite and not that large, and Rosetta had to go
| much deeper into the Sun's gravity well. So, as a non-
| expert who hasn't done the numbers, I'd guess matching pace
| with the dwarf planet would be easier (requiring less delta
| V and/or gravity assists) than Rosetta with the comet.
| messe wrote:
| 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.
| pyuser583 wrote:
| Are you sure that the right xkcd link?
| messe wrote:
| Already noted in a comment below. Too late to edit. It's
| 2 off. It should be xkcd.com/1244.
| perl4ever wrote:
| 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".
| garaetjjte wrote:
| There's mod though! https://forum.kerbalspaceprogram.com/
| index.php?/topic/162200...
| ericbarrett wrote:
| It's quite good as well, written in C++ for speed with
| new versions released every lunar cycle (!). I've done
| some Lagrange orbits with it in the Kerbol solar system.
| Doing it with Realism Overhaul and Real Solar System is a
| bit harder...
| messe wrote:
| Not really that inexplicable, it's a video game. It's not
| for computational reasons, but to make gameplay easier to
| reason about; because again, it's a video game.
|
| The mechanics are simplified, yes, but patched conics is
| quite a good approximation for many cases, and great for
| developing an intuition for the basics.
|
| There is a mod that includes n-body calculations called
| Principia if you're interested in that.
| [deleted]
| perihelions wrote:
| I'd push back against that interpretation of the
| developer's design choices. Kerbal's use of patched conic
| approximations greatly lowers the difficulty of the game
| (it is a game) for most players; it enables a simple and
| coherent UI/UX; and it guarantees fixed orbits that make
| difficult in-space rendezvous like the Apollo program's
| accessible. Like Minecraft cubes, it creates a reliable
| foundation of simple abstractions that people can reason
| about, and build complicated strategies on top of.
| (Wouldn't Minecraft be unplayable if instead of cubes, it
| was arbitrary user-defined convex polyhedra? It's like
| that).
|
| Upping the realism lowers the playability: games and
| simulators are subtly different things. Otherwise we'd
| all be playing STK/Astrogator instead of Kerbal, and
| AutoCAD instead of Minecraft, and sitting in city hall
| basements debugging spreadsheets in place of _Cities:
| Skylines_. The type of limitations that distinguish games
| from serious simulators are not accidents and not
| laziness, but deliberate design choices.
|
| I concede this makes certain interesting topics like
| Lagrange points / halo orbits, masscons, and orbital
| precession inaccessible. That's part of the tradeoff.
| thoughtsimple wrote:
| I think you meant: https://xkcd.com/1244/
| messe wrote:
| Whoops. Yep, that's the one.
|
| Maybe I'll be vindicated when it turns out the planetoid
| is made out of grey goo.
| perihelions wrote:
| It's difficult to believe that ten years from now, there'd
| be any serious options other than Starship and its future
| peers. (Incidentally, the Delta IV is already at end-of-
| life; ULA is replacing it with Vulcan and its Blue Origin
| engines. The final Delta IV-H launches are planned for
| 2023).
|
| https://spacenews.com/ulas-delta-4-heavy-down-to-final-
| five-...
| messe wrote:
| I more meant that it would take at least that size-class
| of heavy lift launch vehicle.
|
| With Starship this would definitely be doable, and I'm
| really optimistic about it; I just wanted to be cautious
| in my predictions.
|
| I also wouldn't be surprised if Delta IV's life gets
| extended. Vulcan is facing plenty of development delays,
| and Blue Origin are yet to produce anything useful.
| [deleted]
| ramraj07 wrote:
| Might there be not some benefits to try to get into orbit
| around this object, like perhaps a free ride to the Oort
| Cloud maybe?
| jfengel wrote:
| There's no such thing as a free ride. If you can soft
| land on it you're already going to the Oort cloud.
|
| You could get a free ride by having it crash into you,
| but that's going to be like catching a bus by letting it
| hit you, at ten thousand miles an hour.
| [deleted]
| perl4ever wrote:
| In a few years, can't we look forward to SpaceX making it
| routine to refuel in orbit? If we assume that's feasible, I
| wonder what sort of missions it would enable, other than
| human spaceflight.
| messe wrote:
| Hopefully yes. I was being conservative with my
| suggestions.
| throwaway316943 wrote:
| Maybe starship will be ready with orbital refueling in time
| to make a faster trip. Imagine being able to do a sample
| return mission from such an object.
| varjag wrote:
| In its apogee it is 0.85 light years away from the Sun.
| orliesaurus wrote:
| I wonder how/IF this will cause anything to spike solar flares?
| that's what's scary to me - all it takes is one big burst and bye
| bye to our tech....
| ceejayoz wrote:
| A dwarf planet wandering around Saturn's orbit isn't gonna do
| very much to the Sun.
| _Microft wrote:
| No, no need to worry. Coronal mass ejections causing
| geomagnetic storms are really something to worry about but this
| thing is just a piece of rock flying around the Sun at very far
| distances (from our point of view). It is coming no closer than
| eleven astronomical units to Sun (1 AU is the mean distance of
| Earth to Sun).
| orliesaurus wrote:
| Yeah I totally misunderstood the distances - my bad.
| _Microft wrote:
| There is a website that visualizes the distances in the
| solar system at the scale of _1 pixel to the diameter of
| Moon_. In the lower right corner there is a symbol with a
| "C" and some lines around it that makes you automatically
| travel at the speed of light. Start the journey, put it on
| an extra screen if you have one and see _nothing_ happen
| for most of the time ;)
|
| The current distance from Sun is shown in the bottom center
| and you can change units in the menu attached to it.
| "Astronomical units" or "light minutes" might be the most
| useful, kilometers or miles if you just want to be blown
| away by the order of magnitude.
|
| https://joshworth.com/dev/pixelspace/pixelspace_solarsystem
| ....
|
| I also submitted it for discussion here:
|
| https://news.ycombinator.com/item?id=27573172
|
| Edit: fixed the scale, it's 1px:diameter of Moon, not
| 1px:distance Earth-Moon as I initially wrote.
| messe wrote:
| I'm not seeing the relation other than it's also in space (so
| is the earth and everything on it by the way).
|
| Why would this do anything to spike solar flares? It's a lump
| of rock and ice 130km across, further out than Saturn. What
| possible mechanism do you think there is that would cause that
| to occur?
| orliesaurus wrote:
| @messe guess you're right - I'll take the downvotes...
| thechao wrote:
| You voiced your comment as more speculative rather than as
| a question. Please don't stop asking questions!
| orliesaurus wrote:
| Ty!
| DaiPlusPlus wrote:
| > It's a lump of rock and ice 130km across
|
| That's it? I was hoping for something at least the size of
| Texas...
| messe wrote:
| It's almost certainly bigger than an olympic swimming pool,
| and definitely larger than an American football field.
| hownottowrite wrote:
| It won't do anything.
|
| Also, Carrington class events are very rare. You should worry
| more about space junk crashing into important things and even
| then it's not much of a worry.
|
| https://warwick.ac.uk/newsandevents/pressreleases/likelihood...
| EarthLaunch wrote:
| > The analysis shows that 'severe' magnetic storms occurred
| in 42 out of the last 150 years, and 'great' super-storms
| occurred in 6 years out of 150
|
| That seems extremely imminent, like in my lifetime. How many
| of these events would shut down tech for months or years? Are
| those odds worth risking civilization over?
| 8note wrote:
| As far as space weather goes, I remember the forecast being
| severe all through September while I was doing magnetic
| surveying in northern Sask.
|
| Sever might not be so dangerous
| hownottowrite wrote:
| How many? Like zero.
|
| Big storms happen all the time. They'll knock out a few
| power stations or shake up GPS and communications.
|
| The Carrington level events are far more rare. We had a
| near miss in 2012. That would've been very exciting.
| bnjemian wrote:
| I say we catch that sucker, tow it into our neck of the woods as
| a second moon, and use it as a space port. Are there a million
| problems with this proposal? Yes. But would it be totally rad to
| do this? Also yes.
| sp332 wrote:
| With such a huge difference between peri- and aphelion, won't
| it be moving extremely fast when it's nearby?
| peeters wrote:
| Well yes, and 11 AU is still further than Saturn's orbit. The
| asteroid belt contains objects of similar size that are far
| closer.
| temp0826 wrote:
| Reminded me of the game Bungie made pre-Halo called Marathon,
| which mostly took place on a colony ship that was made out of
| one of Mar's moons (Deimos)
| dzink wrote:
| Love the creativity! That said, the moon stabilized earth's
| rotation angle, giving us the seasons, and it also drives huge
| chunks of life ecosystems and weather with the tides. So adding
| a second body in rotation to Earth with such superpowers would
| muck with a lot of stuff along the way. Maybe put it around
| Mars instead?
| raxxorrax wrote:
| Crash it on mars to revive it's geologic activity. Poor man's
| terraforming, just have to wait a few million years for it to
| cool down.
| krasin wrote:
| The diameter of this asteroid is estimated to be ~160 km,
| which is 21.7 times less than Moon with d=3474 km. Assuming
| similar density, the mass of the new asteroid is 10000 less
| than Moon and it's unlikely to affect much.
| rob74 wrote:
| Ah, ok, good to know! When I read "dwarf planet", I
| automatically assumed it to be bigger than (or at least
| comparable in size to) the moon, which is a mere sattelite
| of a small planet. Then again, even Pluto, which was
| considered for a long time to be an "actual" planet, is
| smaller than the moon...
| cbkeller wrote:
| Earth's moon is freakishly large by moon standards, as it
| turns out!
|
| > At about one-quarter the diameter of Earth (comparable
| to the width of Australia), it [the Moon] is the largest
| natural satellite in the Solar System relative to the
| size of its planet, the fifth largest satellite in the
| Solar System overall, and is larger than any dwarf
| planet.
|
| [1] https://en.wikipedia.org/wiki/Moon
| PhasmaFelis wrote:
| I'm gonna level with you, I stopped reading at "superpowers"
| and as a result this sounds like a great idea.
| lmilcin wrote:
| But why? Don't we already have a moon?
| Mountain_Skies wrote:
| Think of all of the opportunities to write software to
| calculate the complicated changes required for astrology.
| legostormtroopr wrote:
| We have moon, but what about second moon?
| disillusioned wrote:
| What if, and hear me out here, we give _our_ moon its _own_
| moon? Like letting my dog have a lizard for a pet!
| throwaway378037 wrote:
| I don't think he knows about second moon!
| rishav_sharan wrote:
| It's like asking, why have 2nd breakfast when you had one
| breakfast. We must channel our inner hobbits and think big
| tradesurplus wrote:
| Why not tow it into Venus or Mars orbit instead? They could do
| with the benefits of having a decent sized moon. It would make
| terraforming and long term habitation more straightforward and
| likely to succeed as well as providing lots of useful materials
| feedstock atop the gravity well.
| herendin2 wrote:
| If this was remotely possible for us then we could also talk
| about towing the Earth a little further from the Sun to fix
| climate change
|
| (It's not possible in any reasonable time)
| Koshkin wrote:
| R-right... What can go wrong?
| [deleted]
| sneak wrote:
| What sort of propulsion mechanisms (even those that are
| currently physically plausible but entirely outside our
| technology, so, for example, solar sails or nuclear torchships,
| but not, say, warp drive) could possibly be used to achieve
| such a task?
| peeters wrote:
| Scott Manley had a recent video talking about the work
| involved in moving the Earth, that you might find
| interesting. Basically the most "plausible" approach might be
| to move the moon and use it to drag the Earth. Similarly the
| best way to move another large object might be to carefully
| move other objects small amounts to do precise gravity
| assists.
|
| https://youtu.be/5StYppuJ_lg
| smegger001 wrote:
| wouldn't that require a solution to the three body problem
| to make such precise gravity assists?
| ericbarrett wrote:
| Only if the target was far and we did it in one shot.
| Otherwise you'd just measure the state of things and make
| corrections for your next maneuver, the way we do for
| trips outside Earth's orbit today.
| kbelder wrote:
| While we can't 'solve' the three body problem, we can
| make increasingly accurate estimations. Enough to usually
| get orbital mechanics right in the short-term.
|
| For a setting where we were getting it right until we got
| it wrong, see Niven's "A World out of Time".
| Diti wrote:
| The Caplan Thruster of this video:
| https://youtu.be/v3y8AIEX_dU
| messe wrote:
| Nuclear would do it. Essentially use the dwarf planet itself
| as reaction mass, accelerating it with either nuclear thermal
| propulsion or a nuclear powered mass driver.
|
| Highly impractical, and would take centuries to slow it down
| enough.
| [deleted]
| FiatLuxDave wrote:
| So, an interesting thing about high eccentricity orbits like
| 2014 UN271 has, is that they have a much higher ratio of
| energy (kinetic and potential) to momentum around the sun
| than a nearly circular orbit like say, Earth has. One can
| think of an orbit as being a superposition of a purely
| circular orbit and a purely radial one, with all the momentum
| around the sun being in the circular one. Any leftover energy
| above what is needed for the circular component goes into the
| radial component. In this case, almost all the energy is in
| the radial component.
|
| What this means is that if do you have a way to move it into
| a circular orbit around the sun, you could gain energy from
| the process, rather than having it cost energy. Maybe the
| best way to gather that energy, and possibly to move it as
| well, would be through gravitational assists, since they are
| lossless kinematic interactions. The energy gathered could
| then be used to build more of whatever is doing the
| interaction, exponentially speeding up the process.
| teraflop wrote:
| Just for fun, I did some ballpark calculations. Let's
| consider the simpler problem of just putting 2014 UN271 into
| a circular orbit around the sun at its periapsis of 11 AU.
|
| Calculating the exact path of an orbiting body under thrust
| is difficult. But the object will be within 1% of the desired
| orbital radius for roughly a 22-degree arc of its orbit
| centered on the periapsis, during which time its path will be
| closely approximated by a circular arc 648 million km long.
|
| Let's say that over the course of this arc, we want to slow
| it from its initial speed of 12.7 km/s to the required
| circular orbital speed of 9.0 km/s. That means we need a
| continuous deceleration of roughly 0.00006 m/s^2 over a
| period of 2 years.
|
| Assume that we'll produce this thrust by launching material
| from the object into space using mass drivers. By the
| Tsiolkovsky rocket equation, the smaller the fraction of the
| object that we want to use as reaction mass, the larger our
| "exhaust" velocity has to be. If we want to only lose 10% of
| the total starting mass, we need our exhaust velocity to be
| about 10x the _total_ desired delta-V -- that is, 37 km /s,
| or roughly 0.01% the speed of light. This is a tall order,
| but let's say we can somehow solve the engineering problems
| and build a linear accelerator that can get rocks moving that
| fast.
|
| Assume the object is 160 km in diameter and made entirely of
| ice, giving it a total mass of about 2.0e18 kg. The total
| required momentum change is therefore about 7.5e21 kg m/s,
| and the required energy input is 1.4e26 J. If we assume
| constant thrust for two years, this means we would have to
| launch about 3.2 million tons of material per second,
| averaging out to 2.2 exawatts of power required.
|
| To put this number in perspective, it's several million times
| higher than the average electricity generation of the entire
| planet Earth. To generate this much power using
| 100%-efficient solar panels, at a distance of 11 AU from the
| sun, you would need a solar array approximately half the
| diameter of the sun itself.
|
| So a direct propulsion approach, at least, doesn't really
| seem like it's within the realm of feasibility.
| minitoar wrote:
| Yeah probably better off with a project Orion type
| approach.
| hoseja wrote:
| We could aerobrake it around Saturn.
| ashton314 wrote:
| Can we give the moon a moon instead?
| Waterluvian wrote:
| I want nothing more than for my species to enter the federation
| of species with a reputation for being the ones who did that
| absolutely ridiculous prank using 10% of their GDP for a
| century.
| yinyang_in wrote:
| All aside, thanks for giving me big laugh :D
| monkeycantype wrote:
| Is it a comety composition? Crash it into mars for some ocean
| and atmosphere?
| XorNot wrote:
| I keep hoping we'll get lucky in my lifetime and something
| big like that will just hit Mars on it's own.
|
| It would be a hell of a world to go from "desert" to "so
| we've got all these new oceans to name and also you can't
| breathe it but ground level pressure is one atmosphere".
| tmp538394722 wrote:
| I think seeing something world changingly large randomly
| smashing into our next door neighbor would leave me feeling
| something other than lucky.
|
| But sure if it's gonna happen, let's get the neighbors a
| pool! Just let me uh... change my shorts.
| rob74 wrote:
| I say, better to have it happen on Mars than on Earth!
| Such an event would probably even have the positive
| effect of raising awareness and increasing funding of
| programmes that monitor asteroids hazardous to earth and
| technologies to deflect them.
| matkoniecz wrote:
| https://en.wikipedia.org/wiki/Comet_Shoemaker-Levy_9
|
| An entire fragmented comet impacted Jupiter in 1994
|
| > Over the next six days, 21 distinct impacts were
| observed, with the largest coming on July 18 at 07:33 UTC
| when fragment G struck Jupiter. This impact created a
| giant dark spot over 12,000 km (7,500 mi) across, and was
| estimated to have released an energy equivalent to
| 6,000,000 megatons of TNT (600 times the world's nuclear
| arsenal).[24] Two impacts 12 hours apart on July 19
| created impact marks of similar size to that caused by
| fragment G, and impacts continued until July 22, when
| fragment W struck the planet.[25]
| tmp538394722 wrote:
| This is awesome. Thanks for sharing.
|
| > Although the impacts took place on the side of Jupiter
| hidden from Earth, Galileo, then at a distance of 1.6 AU
| (240 million km; 150 million mi) from the planet, was
| able to see the impacts as they occurred.
|
| We're getting better at this stuff!
| lumost wrote:
| I'm not sure how the mechanics of a 200 km wide comety like
| object hitting Mars at ~25 km/s would work out, but I'm
| reasonably certain that it would result in a major
| resurfacing event. I'd venture that the majority of the
| gasses would retain escape velocity following impact.
| tshaddox wrote:
| Well, since we're just assuming we could meaningfully
| change it's trajectory we might as well also assume we
| could slow it down!
| hodgesrm wrote:
| Slowing it down would take way more energy than just
| nudging in a different direction. You might be better off
| trying to break it up into smaller pieces.
| monkeycantype wrote:
| Taking notes.... Small pieces... uh ha, yep got it,..
| Slow it down... yep. What else?
| Scarblac wrote:
| Make sure they hit at a safe distance from our Mars
| rovers, I like them.
| monkeycantype wrote:
| how would we aerobreak it in mars's atmosphere into a
| decaying orbit, so instead of slamming into mars, it
| breaks up and rains down on mars? What can we tell about
| the composition - a solid rock or icy rubble?
| minitoar wrote:
| You get it into an orbit that will have several close
| encounters with Mars or other planets with atmosphere and
| you do a bit of aerobraking/thrusting on each pass.
| lumost wrote:
| The martian atmosphere will have a negligible impact on a
| 200km wide object. Tidal forces would likely shred the
| object and the surface of Mars if an aerobraking maneuver
| was attempted.
| avaldes wrote:
| Shouldn't break by itself with Mars' tidal forces alone?
| DiabloD3 wrote:
| How are you going to deal with the imbalance in charge? It's
| likely that the to-be-moon has a very large charge differential
| between it and the Sun, but also likely between us and it.
| loa_in_ wrote:
| That's true. In extreme cases it could really upset Earth's
| magnetosphere. And since we don't know we can't assume it's
| magnetically inert.
| AudreyDoka wrote:
| Pas mal.
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