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What we know about Earth’s new minimoon
- tedunangst 6y agoBuried lede: it's no longer in earth orbit.
- junon 6y agoThen why is it considered a "mini moon" if it's not a moon at all?
- dwaltrip 6y agoIt’s a former minimoon. It orbited earth for 2.7 years, making numerous revolutions in that time. There is a cool animation in the article that shows the path it took.
- ant6n 6y agoIt’s odd they were able to reconstruct its flight path, which appears to be quite chaotic (in the scientific sense), given that the observations are only from after it left the earth-moon System.
- crazygringo 6y agoWhat specifically seems so odd about it? If we know its trajectory with decent precision when it left, and we know the position and gravitational strength of the earth, moon and sun, and you just plug in the numbers and simulate and it should be quite straightforward. I suppose you're referring to "chaotic" meaning that tiny variations or mismeasurements in its later trajectory would be vastly amplified as its orbits were traced. But my understanding is that such chaotic/unpredictable orbital effects generally show up on the scale of many many thousands of orbits if not much more, not 2 years?
- nsomaru 6y agoThe first “turn” this object makes is almost at a right angle. Seems entirely unintuitive to me. How does this happen?
- Delk 6y agoIt probably passed close to the Moon, and that near pass flung it into the altered trajectory.
- crazygringo 6y agoExactly. And remember that while the low spatial and temporal resolution of the GIF makes it seem like just being a "pixel" off could result in a totally different orbit (like chaos theory)... ...the actual simulation is dealing with distances of hundreds of thousands of miles, simulated over multiple years of time, presumably with something like minute-by-minute, meter-by-meter precision. (Remember, the object itself is only 1-2 meters large.) The "unintuitive right angle" would appear entirely intuitive if you actually watched it slower while zoomed in closer to the moon.
- ant6n 6y agoIt´s counter-intuitive because of the chaotic path. It appears like with every crazy turn this object takes, one would need a couple of extra bits of the initial state - small deviations will result in completely different flight paths. Here, the initial state is of course the final state, but since its reversible that doesn´t really make a difference.
- jagger27 6y agoHow cool would it be if we had probes like Hayabusa or Osiris-Rex ready to go for encounters like this? ʻOumuamua would have been a long shot but this rock seems within reach.
- airstrike 6y agoAlso how about we leave some instrument on the rock even after it departs? Would be interesting to track where it went next
- TeMPOraL 6y agoGenerally there's little point in doing that, unless you want to study the body itself or otherwise care about its presence. That's because to rendezvous with something in space you need to get close to it and bring your velocity relative to it to zero - which puts you on the exact same orbit, so even without attaching to it, you'll go where it goes.
- black_puppydog 6y agoAlso, at 2m diameter, its gravity would be so low that "leaving" a probe on it would mean strapping the probe to it? That would be a funny tech demo for catching a small rock, but if you already do that, why not put it into a stable orbit for further study?
- m4rtink 6y agoAlso landing something on a space rock might not be a huge win from just leaving it in orbit. You see, even if you manage to attach yorself to the thing (and the Philae lander of the Rosetta mission demonstrated is's not easy), the thing usually rotates with one revolution every couple hours. So unlike a cosy stable state vacuum of space with sun in one direction to point the solar panels and Earth in another where you point the antennas, you are now sitting an a pice of material that can freeze you/cook you by convection & Sun an Earth continually change position. Also unlike with a space probe that can have a hot (in the sun) and cold (in the shadow) sides, now you need to handle temperature management from multiple constantly changing angles. Fun! Thats why we don't regularly communicate with NEAR Shoemaker or Rosetta even though both landed on a space rock - they are simply no longer in a working order. That doesn't mean it's impossible - you just need to use a rather more complicated spacecraft for that, than just trying to land a space probe.
- dave_4_bagels 6y agoI've been curious why we don't start pushing de-commissioned satellites / space junk in earth orbit into a moon-like mass orbiting earth? It would take a swarm of maybe a few hundred powered "satellite movers" maybe a decade. But in time, seems like it could become a fantastic means of dealing with space debris surrounding earth especially space junk that can't easily be ditched to re-enter the earth's atmosphere and burn up.
- vosper 6y agoPerhaps it would just move the problem from the earth to the moon? If we're going to the effort to build "satellite movers" to get unwanted/dead satellites to a moon orbit, then perhaps we would be better of just sending them into the sun, or on a path out into deep space?
- kempbellt 6y agoIt would be better to glob them together for a space station to repurpose the materials. A lot of time, energy and money is spent getting material into orbit. No sense wasting it, unless it's completely useless. Then de-orbiting in the Earth's atmosphere is the cheapest solution.
- dogma1138 6y agoI would say having shit in lunar orbit might be a bigger problem since they will not burn on reentry. Sure it’s not a problem now but by the time we can push junk into a lunar orbit the moon might be quite a bit more populated.
- dave_4_bagels 6y agoI thought about that too, but the benefit of an orbiting "globule" of satellite waste is that in time it would have it's own micro-gravity and require less energy to "commit" waste to a mini-moon than pushing out of earth's orbit to the sun? I haven't done the napkin math but maybe I'm sorely mistaken in terms of the physics involved. Could be interesting to lower the cost by pushing into a huge mass and then once it was too large pushing that mass into the sun?
- politelemon 6y agoHere's a quick read of that one time Minor Planet Center cataloged the Rosetta Space Probe as an asteroid https://thenerdnextdoor.com/tag/2007-vn84/ https://thenerdnextdoor.com/tag/2007-vn84/
- moralsupply 6y agoWhy did it take so long to figure out we have 2 moons?
- kennywinker 6y agoOne of them is very small, and was only around for 2.7 years
- ConceptJunkie 6y agoAnd it's gone now.
- crazygringo 6y agoUgh. I hate this new supposed term "minimoon" -- it's sensationalistic and misleading. This object is 1 to 2 meters in diameter, was captured by Earth for just 2.7 years, and with an extremely irregular orbit. By contrast, a moon requires a "relatively stable orbit" [1], which this clearly did not have. Can we just call it what it actually is? It's an asteroid. It revolves around the Sun, and it was very briefly a temporary satellite of the Earth. [1] https://en.wikipedia.org/wiki/Claimed_moons_of_Earth https://en.wikipedia.org/wiki/Claimed_moons_of_Earth
- rdiddly 6y agoThe word "new" isn't exactly well placed either. Wanna go see my new car? I sold it to a guy last April.
- s_gourichon 6y agoIt's new because I only realized I had that second car after I sold it. Smells clickbait :-/
- sebow 6y agoWaiting for the ancient aliens episode on this any second now
- prvc 6y agoIn the gif, the path intersected the disc representing the Earth's position a few times. What was the actual minimum distance between the object and the Earth's surface?
- tetris11 6y ago> According to the JPL Small-Body Database, the closest approach to Earth has already occurred, on 4 April 2019, when it approached to a distance of 13,121 km (8,153 mi). https://en.wikipedia.org/wiki/2020_CD3 https://en.wikipedia.org/wiki/2020_CD3
- Haga 6y agoIt's interesting to see the defending gravity of the moon visualized. Any large impactor makes a similar journey?