Interstellar Interlopers, Coming in from the great beyond |
Interstellar Interlopers, Coming in from the great beyond |
Oct 27 2017, 01:40 PM
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#1
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Member Group: Members Posts: 541 Joined: 17-November 05 From: Oklahoma Member No.: 557 |
They finally found a chunk of something coming into the Solar System. Something much bigger than cosmic rays or dust particles.
Asteroid/comet in hyperbolic trajectory |
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Oct 31 2017, 12:46 AM
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#2
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Senior Member Group: Members Posts: 4252 Joined: 17-January 05 Member No.: 152 |
That's called the impact parameter. It's just sqrt[(e + 1)/(e - 1)]r_p, where e is the eccentricity and r_p the perihelion distance. Plugging in the elements gives about 3.3 r_p, or about 0.85 AU, for the impact parameter.
So there should be 8 times as many such objects coming in with impact parameters inside double that, ie 1.7 AU. Etc. Double the distance means 1/4 the brightness (at the same observation distance). Anyway, the prospects should be not bad for spotting more farther out if we can reach the required sensitivity... |
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Oct 31 2017, 06:25 PM
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#3
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
I think the two most important kinds of scrutiny for such an object would be:
1) Isotopic analysis of heavy elements. 2) Millimeter scale resolution of chondritic (or the equivalent?) material. Those would tell us something about how the system evolved differently from ours. We still don't understand what flash-fried the chondrules in our solar system, and seeing another analogue would be tremendously interesting. The kinds of things you'd see from a flyby would certainly be interesting, but in this regard it's "just another" very small icy body, perhaps not very different from ones in our solar system, but whatever it's like, it wouldn't necessarily tell us about its system, just as a comet nucleus in our solar system doesn't tell you much about Saturn or Venus. So I think a very valuable mission would be one that landed and performed in situ analysis of the stuff within an arm's reach. Perhaps lithobraking solves the hard problem of the delta-v. Have a small payload encased in concentric shells of crushable shield to spread out the impact delta-v over a longer time. The failed Deep Space 2 probes to Mars would be the closest analogue – 2.4 kg per probe, intended to survive impact. There, though, the delta-v was much less, there was some aerobraking, and – again – they failed despite that. But if you had many hundreds of kg of shield devoted to permitting the survival of a ~3 kg probe, maybe this gets easier. |
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Nov 1 2017, 08:02 PM
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#4
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Senior Member Group: Members Posts: 2346 Joined: 7-December 12 Member No.: 6780 |
... Perhaps lithobraking solves the hard problem of the delta-v. Have a small payload encased in concentric shells of crushable shield to spread out the impact delta-v over a longer time. The failed Deep Space 2 probes to Mars would be the closest analogue – 2.4 kg per probe, intended to survive impact. There, though, the delta-v was much less, there was some aerobraking, and – again – they failed despite that. But if you had many hundreds of kg of shield devoted to permitting the survival of a ~3 kg probe, maybe this gets easier. Overcoming the speed of sound within the solid material of the shield would certainly be a challenge. Longitudinal forces in solids usually are transmitted with about the speed of sound of the solid medium. So, the mechanism would need something faster, like electromagnetic fields. |
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