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Interstellar Interloper, Coming in from the great beyond
Gladstoner
post Oct 30 2017, 05:46 AM
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I gather that it would be prudent to give this region of the sky some extra scrutiny in minor planet/comet surveys. At least the earlier detection of an approaching interstellar object would be more likely. How nice would it have been for Hubble to be ready (or JWST in the future)?.... not that 2017 U1 would have been detected any earlier.
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Paolo
post Oct 30 2017, 05:52 AM
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that was fast!

Palomar Optical Spectrum of Hyperbolic Near-Earth Object A/2017 U1

QUOTE
We present optical spectroscopy of the recently discovered hyperbolic near-Earth object A/2017 U1, taken on 25 Oct 2017 at Palomar Observatory. Although our data are at a very low signal-to-noise, they indicate a very red surface at optical wavelengths without significant absorption features.
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Floyd
post Oct 30 2017, 11:55 AM
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QUOTE (Gladstoner @ Oct 30 2017, 01:40 AM) *
Path of approach of A/2017 U1 plotted in Voyager II: (Solar apex marked with yellow X)



The spiral motion is due to the relative motion of ??? I'm not quite understanding the reference frame.


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Floyd
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Ames
post Oct 30 2017, 12:42 PM
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QUOTE (Floyd @ Oct 30 2017, 11:55 AM) *
The spiral motion is due to the relative motion of ??? I'm not quite understanding the reference frame.


Earth - Parallax.
Apparent motion against the background stars.

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TheAnt
post Oct 30 2017, 03:08 PM
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QUOTE (JRehling @ Oct 30 2017, 01:48 AM) *
TheAnt,

Truly reaching this object will be quite difficult, but compared to sending a mission (much less a sample return!!!) to another star's system, it's outrageously easy.
I think getting mere in situ isotopic analysis of heavier elements from an object like this would be extraordinarily valuable....


I agree in full about the value of getting such a sample, it would add to the knowledge about our own Kupier or Oort belt also.
And that was the reason I did that back-of-envelope type of calculation.
Only to find that a sample return would require a spacecraft of Frankensteinian proportions, so for several reasons not within a magnitude of our current capabilities.

That's why I mentioned cubesats/U-class spacecrafts first, cheap components built by any interested university, comparatively easy to store and to be sent by the dozen.
So yes, in situ or remote by a small craft that might even fly in formation is possible, one of the cubesats might even be sent to collide to get additional data.

Smaller objects will indeed be more frequent, but harder to find at the distance needed to get our interceptor on the way in time.
In addition, fragment of comets might have similar orbits making the tracking even harder.

Now a search for any such that might have impacted on the Moon or any other object without an atmosphere is worth thinking about.
Even though the shattered remains would be a bit less pristine, extremely heated up rather, it would still be possible to get some data.

After my previous post I realized one kind of probe in development that indeed would be able to reach A/2017 U1 - the sail in development by Breakthrough Starshot.
And that is a much more realistic target for such a spacecraft, accelerated to 30-50 Km/s instead of 50 000 km/s or whatever they hope for.
Even that tiny proposed transmitter ˝ W or whatever, might be able to send the data back - a nice advantage.
Ooops! I better stop, all of a sudden I appear to be a supporter or Phlebotinum technology! =)
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Gladstoner
post Oct 30 2017, 03:36 PM
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QUOTE (TheAnt @ Oct 30 2017, 10:08 AM) *
After my previous post I realized one kind of probe in development that indeed would be able to reach A/2017 U1 - the sail in development by Breakthrough Starshot.
And that is a much more realistic target for such a spacecraft, accelerated to 30-50 Km/s instead of 50 000 km/s or whatever they hope for.
Even that tiny proposed transmitter ˝ W or whatever, might be able to send the data back - a nice advantage.
Ooops! I better stop, all of a sudden I appear to be a supporter or Phlebotinum technology! =)


Interesting!

FWIW, here is an ephemeris of A/2017 U1 for the next century in ~half-year increments (from JPL HORIZONS). Shown are object position date, sky coordinates, magnitude, distance from sun in AU (range), and range rate.

Date__(UT)__HR:MN R.A._(ICRF/J2000.0)_DEC APmag r rdot
***************************************************************************

2017-Jan-01 00:00 18 10 48.25 +24 14 08.4 30.25 5.480932452578 -31.5363755
2017-Jul-03 00:00 15 32 00.23 +53 39 52.0 25.78 1.889032162719 -38.5709524
2018-Jan-02 00:00 23 31 39.21 +09 15 17.0 27.69 2.865905946364 35.3016311
2018-Jul-04 00:00 00 54 46.46 +24 45 49.3 30.73 6.310209706508 30.9243218
2019-Jan-03 00:00 23 47 03.93 +19 48 22.3 32.33 9.492071071897 29.4799470
2019-Jul-05 00:00 00 23 59.88 +24 55 04.3 33.48 12.56469466334 28.7362338
2020-Jan-04 00:00 23 49 03.67 +21 41 49.5 34.36 15.57559887711 28.2766783
2020-Jul-05 00:00 00 13 38.17 +24 54 51.9 35.07 18.54638060269 27.9624986
2021-Jan-04 00:00 23 49 51.33 +22 31 22.7 35.69 21.48873606470 27.7322127
2021-Jul-06 00:00 00 08 21.67 +24 54 13.9 36.22 24.40982212577 27.5556680
2022-Jan-05 00:00 23 50 17.39 +22 59 32.2 36.69 27.31424412971 27.4149317
2022-Jul-07 00:00 00 05 08.78 +24 53 44.4 37.11 30.20527197114 27.3002568
2023-Jan-06 00:00 23 50 33.95 +23 17 50.3 37.50 33.08517864084 27.2043140
2023-Jul-08 00:00 00 02 58.39 +24 53 22.8 37.84 35.95579599000 27.1233533
2024-Jan-07 00:00 23 50 45.19 +23 30 43.4 38.17 38.81844478692 27.0537124
2024-Jul-08 00:00 00 01 23.90 +24 53 06.4 38.46 41.67432291663 26.9940086
2025-Jan-07 00:00 23 50 53.11 +23 40 17.5 38.75 44.52427964797 26.9421107
2025-Jul-09 00:00 00 00 11.88 +24 52 51.7 39.00 47.36918076463 26.8974383
2026-Jan-08 00:00 23 50 58.77 +23 47 39.5 39.26 50.20960167493 26.8581905
2026-Jul-10 00:00 23 59 15.03 +24 52 37.3 39.48 53.04620010132 26.8240801
2027-Jan-09 00:00 23 51 02.95 +23 53 29.1 39.71 55.87935864384 26.7937684
2027-Jul-11 00:00 23 58 28.92 +24 52 22.6 39.91 58.70958668171 26.7673787
2028-Jan-10 00:00 23 51 06.18 +23 58 12.2 40.12 61.53711806064 26.7437097
2028-Jul-11 00:00 23 57 50.79 +24 52 07.6 40.30 64.36234819915 26.7228467
2029-Jan-10 00:00 23 51 08.78 +24 02 05.6 40.49 67.18540107417 26.7036419
2029-Jul-12 00:00 23 57 18.82 +24 51 53.1 40.66 70.00659655710 26.6863708
2030-Jan-11 00:00 23 51 11.07 +24 05 21.9 40.84 72.82596926704 26.6701114
2030-Jul-13 00:00 23 56 51.68 +24 51 39.7 40.99 75.64376934851 26.6552907
2031-Jan-12 00:00 23 51 13.17 +24 08 10.1 41.16 78.45995555855 26.6409568
2031-Jul-14 00:00 23 56 28.49 +24 51 28.1 41.30 81.27473208547 26.6274029
2032-Jan-13 00:00 23 51 15.19 +24 10 36.3 41.45 84.08799925892 26.6136987
2032-Jul-14 00:00 23 56 08.47 +24 51 18.6 41.58 86.89992433998 26.6004116
2033-Jan-13 00:00 23 51 17.15 +24 12 45.7 41.73 89.71036367251 26.5869003
2033-Jul-15 00:00 23 55 51.03 +24 51 11.5 41.85 92.51947003209 26.5737846
2034-Jan-14 00:00 23 51 19.01 +24 14 41.6 41.99 95.32708409903 26.5603725
2034-Jul-16 00:00 23 55 35.67 +24 51 06.7 42.10 98.13338319320 26.5474188
2035-Jan-15 00:00 23 51 20.72 +24 16 26.1 42.23 100.9382376756 26.5345316
2035-Jul-17 00:00 23 55 21.92 +24 51 03.3 42.34 103.7418799516 26.5227040
2036-Jan-16 00:00 23 51 22.18 +24 18 00.5 42.46 106.5442180234 26.5115771
2036-Jul-17 00:00 23 55 09.45 +24 51 00.3 42.56 109.3455395567 26.5019409
2037-Jan-16 00:00 23 51 23.34 +24 19 25.2 42.68 112.1457872309 26.4931472
2037-Jul-18 00:00 23 54 58.00 +24 50 56.9 42.78 114.9452816962 26.4858139
2038-Jan-17 00:00 23 51 24.25 +24 20 41.3 42.89 117.7439584064 26.4793249
2038-Jul-19 00:00 23 54 47.43 +24 50 52.5 42.98 120.5421316165 26.4743190
2039-Jan-18 00:00 23 51 24.93 +24 21 49.2 43.09 123.3397045015 26.4699764
2039-Jul-20 00:00 23 54 37.69 +24 50 47.1 43.18 126.1369684489 26.4666519
2040-Jan-19 00:00 23 51 25.50 +24 22 50.1 43.28 128.9337854645 26.4634958
2040-Jul-20 00:00 23 54 28.70 +24 50 40.7 43.36 131.7304236184 26.4610408
2041-Jan-19 00:00 23 51 26.03 +24 23 45.0 43.46 134.5267014939 26.4585773
2041-Jul-21 00:00 23 54 20.46 +24 50 33.8 43.54 137.3228545106 26.4565905
2042-Jan-20 00:00 23 51 26.56 +24 24 35.1 43.63 140.1186566277 26.4542362
2042-Jul-22 00:00 23 54 12.92 +24 50 27.1 43.71 142.9143240201 26.4519119
2043-Jan-21 00:00 23 51 27.19 +24 25 21.5 43.80 145.7095951991 26.4488311
2043-Jul-23 00:00 23 54 06.06 +24 50 20.9 43.88 148.5046609684 26.4455781
2044-Jan-22 00:00 23 51 27.89 +24 26 04.9 43.96 151.2992201805 26.4415150
2044-Jul-23 00:00 23 53 59.82 +24 50 15.8 44.03 154.0934496632 26.4371469
2045-Jan-22 00:00 23 51 28.68 +24 26 46.2 44.12 156.8870283178 26.4317178
2045-Jul-24 00:00 23 53 54.10 +24 50 11.8 44.19 159.6801401032 26.4258816
2046-Jan-23 00:00 23 51 29.51 +24 27 25.9 44.27 162.4724718766 26.4192610
2046-Jul-25 00:00 23 53 48.83 +24 50 09.1 44.33 165.2642466500 26.4127921
2047-Jan-24 00:00 23 51 30.32 +24 28 03.9 44.41 168.0551860974 26.4061158
2047-Jul-26 00:00 23 53 43.88 +24 50 07.1 44.48 170.8455768218 26.4000655
2048-Jan-25 00:00 23 51 31.06 +24 28 40.1 44.55 173.6351989204 26.3942348
2048-Jul-26 00:00 23 53 39.16 +24 50 05.4 44.61 176.4244060000 26.3894526
2049-Jan-25 00:00 23 51 31.66 +24 29 14.1 44.69 179.2130070134 26.3852944
2049-Jul-27 00:00 23 53 34.62 +24 50 03.4 44.75 182.0013795829 26.3824557
2050-Jan-26 00:00 23 51 32.13 +24 29 45.5 44.82 184.7893297743 26.3802049
2050-Jul-28 00:00 23 53 30.25 +24 50 00.8 44.88 187.5772360404 26.3789347
2051-Jan-27 00:00 23 51 32.52 +24 30 14.6 44.95 190.3648762331 26.3778834
2051-Jul-29 00:00 23 53 26.08 +24 49 57.5 45.00 193.1526084366 26.3776262
2052-Jan-28 00:00 23 51 32.85 +24 30 41.4 45.07 195.9401713849 26.3774871
2052-Jul-29 00:00 23 53 22.10 +24 49 53.7 45.13 198.7278960412 26.3778679
2053-Jan-28 00:00 23 51 33.18 +24 31 06.2 45.19 201.5154800279 26.3779210
2053-Jul-30 00:00 23 53 18.36 +24 49 49.5 45.24 204.3032353277 26.3780759
2054-Jan-29 00:00 23 51 33.54 +24 31 29.6 45.31 207.0908264328 26.3776450
2054-Jul-31 00:00 23 53 14.86 +24 49 45.5 45.36 209.8785399827 26.3771736
2055-Jan-30 00:00 23 51 33.96 +24 31 52.0 45.42 212.6659979793 26.3759706
2055-Aug-01 00:00 23 53 11.62 +24 49 41.8 45.47 215.4534686765 26.3744406
2056-Jan-31 00:00 23 51 34.45 +24 32 13.7 45.53 218.2405487454 26.3718108
2056-Aug-01 00:00 23 53 08.61 +24 49 38.8 45.58 221.0274973699 26.3686251
2057-Jan-31 00:00 23 51 34.99 +24 32 35.1 45.64 223.8138932763 26.3644430
2057-Aug-02 00:00 23 53 05.81 +24 49 36.6 45.69 226.6000064676 26.3600162
2058-Feb-01 00:00 23 51 35.56 +24 32 56.3 45.75 229.3854289017 26.3548746
2058-Aug-03 00:00 23 53 03.16 +24 49 35.1 45.79 232.1704758092 26.3497464
2059-Feb-02 00:00 23 51 36.11 +24 33 17.2 45.85 234.9547887149 26.3443557
2059-Aug-04 00:00 23 53 00.61 +24 49 34.2 45.89 237.7387558508 26.3396530
2060-Feb-03 00:00 23 51 36.60 +24 33 37.5 45.95 240.5220705249 26.3353909
2060-Aug-04 00:00 23 52 58.09 +24 49 33.2 45.99 243.3051736701 26.3323038
2061-Feb-03 00:00 23 51 36.98 +24 33 56.8 46.05 246.0877883402 26.3298305
2061-Aug-05 00:00 23 52 55.60 +24 49 31.9 46.09 248.8703861956 26.3284595
2062-Feb-04 00:00 23 51 37.27 +24 34 14.8 46.15 251.6526845958 26.3275742
2062-Aug-06 00:00 23 52 53.13 +24 49 30.0 46.19 254.4351439185 26.3277427
2063-Feb-05 00:00 23 51 37.49 +24 34 31.5 46.24 257.2174488946 26.3283175
2063-Aug-07 00:00 23 52 50.71 +24 49 27.5 46.28 260.0000394086 26.3296212
2064-Feb-06 00:00 23 51 37.68 +24 34 47.0 46.33 262.7825631934 26.3308361
2064-Aug-07 00:00 23 52 48.37 +24 49 24.4 46.37 265.5654372282 26.3323923
2065-Feb-06 00:00 23 51 37.85 +24 35 01.4 46.42 268.3482733287 26.3336897
2065-Aug-08 00:00 23 52 46.12 +24 49 21.0 46.46 271.1314623971 26.3351963
2066-Feb-07 00:00 23 51 38.06 +24 35 15.0 46.51 273.9145733456 26.3361683
2066-Aug-09 00:00 23 52 44.01 +24 49 17.6 46.55 276.6979746497 26.3369434
2067-Feb-08 00:00 23 51 38.31 +24 35 28.2 46.60 279.4812060583 26.3368044
2067-Aug-10 00:00 23 52 42.03 +24 49 14.4 46.63 282.2646177022 26.3362287
2068-Feb-09 00:00 23 51 38.62 +24 35 41.2 46.68 285.0477139224 26.3346920
2068-Aug-10 00:00 23 52 40.19 +24 49 11.6 46.72 287.8308317662 26.3327335
2069-Feb-09 00:00 23 51 38.98 +24 35 54.3 46.77 290.6134657804 26.3297552
2069-Aug-11 00:00 23 52 38.46 +24 49 09.4 46.80 293.3959708719 26.3263162
2070-Feb-10 00:00 23 51 39.36 +24 36 07.4 46.85 296.1778614745 26.3221299
2070-Aug-12 00:00 23 52 36.80 +24 49 07.7 46.88 298.9595424847 26.3181184
2071-Feb-11 00:00 23 51 39.74 +24 36 20.6 46.93 301.7405769084 26.3140978
2071-Aug-13 00:00 23 52 35.19 +24 49 06.3 46.96 304.5214341643 26.3107922
2072-Feb-12 00:00 23 51 40.06 +24 36 33.5 47.01 307.3017298453 26.3078283
2072-Aug-13 00:00 23 52 33.57 +24 49 04.9 47.04 310.0819918084 26.3058512
2073-Feb-12 00:00 23 51 40.33 +24 36 45.7 47.08 312.8618603634 26.3044613
2073-Aug-14 00:00 23 52 31.95 +24 49 03.1 47.11 315.6418739165 26.3042195
2074-Feb-13 00:00 23 51 40.53 +24 36 57.3 47.16 318.4216565204 26.3045300
2074-Aug-15 00:00 23 52 30.33 +24 49 01.0 47.19 321.2017384038 26.3056751
2075-Feb-14 00:00 23 51 40.69 +24 37 08.0 47.23 323.9817161684 26.3069288
2075-Aug-16 00:00 23 52 28.74 +24 48 58.4 47.26 326.7620959899 26.3086960
2076-Feb-15 00:00 23 51 40.84 +24 37 18.1 47.31 329.5424355575 26.3104561
2076-Aug-16 00:00 23 52 27.20 +24 48 55.4 47.33 332.3232149080 26.3125811
2077-Feb-15 00:00 23 51 41.00 +24 37 27.5 47.38 335.1039531217 26.3143279
2077-Aug-17 00:00 23 52 25.73 +24 48 52.3 47.41 337.8851064850 26.3159741
2078-Feb-16 00:00 23 51 41.19 +24 37 36.6 47.45 340.6661631250 26.3169159
2078-Aug-18 00:00 23 52 24.34 +24 48 49.3 47.48 343.4475583501 26.3175945
2079-Feb-17 00:00 23 51 41.43 +24 37 45.6 47.52 346.2287409193 26.3174539
2079-Aug-19 00:00 23 52 23.05 +24 48 46.5 47.55 349.0101221132 26.3168540
2080-Feb-18 00:00 23 51 41.72 +24 37 54.7 47.59 351.7911284179 26.3151602
2080-Aug-19 00:00 23 52 21.86 +24 48 44.2 47.61 354.5721698930 26.3127923
2081-Feb-18 00:00 23 51 42.05 +24 38 04.1 47.65 357.3526656288 26.3094031
2081-Aug-20 00:00 23 52 20.73 +24 48 42.3 47.68 360.1330427424 26.3057455
2082-Feb-19 00:00 23 51 42.40 +24 38 13.7 47.72 362.9127467774 26.3015826
2082-Aug-21 00:00 23 52 19.65 +24 48 41.0 47.75 365.6922599466 26.2975583
2083-Feb-20 00:00 23 51 42.74 +24 38 23.4 47.79 368.4710831365 26.2934393
2083-Aug-22 00:00 23 52 18.57 +24 48 39.9 47.81 371.2497695288 26.2900171
2084-Feb-21 00:00 23 51 43.04 +24 38 33.0 47.85 374.0278720167 26.2871290
2084-Aug-22 00:00 23 52 17.48 +24 48 38.8 47.88 376.8059860250 26.2853655
2085-Feb-21 00:00 23 51 43.28 +24 38 42.2 47.91 379.5836783193 26.2842374
2085-Aug-23 00:00 23 52 16.37 +24 48 37.4 47.94 382.3615591870 26.2840748
2086-Feb-22 00:00 23 51 43.46 +24 38 51.0 47.98 385.1391871696 26.2843147
2086-Aug-24 00:00 23 52 15.24 +24 48 35.7 48.00 387.9171567196 26.2853453
2087-Feb-23 00:00 23 51 43.61 +24 38 59.1 48.04 390.6949897075 26.2866869
2087-Aug-25 00:00 23 52 14.12 +24 48 33.6 48.06 393.4732557222 26.2886114
2088-Feb-24 00:00 23 51 43.75 +24 39 06.7 48.10 396.2514440776 26.2904232
2088-Aug-25 00:00 23 52 13.02 +24 48 31.2 48.12 399.0301005893 26.2923505
2089-Feb-24 00:00 23 51 43.89 +24 39 14.0 48.16 401.8086806126 26.2939102
2089-Aug-26 00:00 23 52 11.96 +24 48 28.7 48.18 404.5877061803 26.2954949
2090-Feb-25 00:00 23 51 44.05 +24 39 21.0 48.22 407.3665956339 26.2965449
2090-Aug-27 00:00 23 52 10.97 +24 48 26.2 48.24 410.1458442877 26.2972620
2091-Feb-26 00:00 23 51 44.25 +24 39 27.9 48.28 412.9248423800 26.2970596
2091-Aug-28 00:00 23 52 10.03 +24 48 23.9 48.30 415.7040726003 26.2962758
2092-Feb-27 00:00 23 51 44.48 +24 39 35.0 48.33 418.4829013260 26.2945387
2092-Aug-28 00:00 23 52 09.16 +24 48 22.0 48.36 421.2618006803 26.2923453
2093-Feb-27 00:00 23 51 44.73 +24 39 42.3 48.39 424.0401357992 26.2893477
2093-Aug-29 00:00 23 52 08.33 +24 48 20.4 48.41 426.8184085677 26.2860161
2094-Feb-28 00:00 23 51 45.00 +24 39 49.8 48.45 429.5960196202 26.2821596
2094-Aug-30 00:00 23 52 07.51 +24 48 19.1 48.47 432.3735266968 26.2785692
2095-Mar-01 00:00 23 51 45.24 +24 39 57.3 48.50 435.1503861705 26.2752485
2095-Aug-31 00:00 23 52 06.69 +24 48 17.9 48.52 437.9272188157 26.2728050
2096-Mar-01 00:00 23 51 45.45 +24 40 04.7 48.56 440.7035255146 26.2709070
2096-Aug-31 00:00 23 52 05.85 +24 48 16.6 48.58 443.4799688578 26.2699776
2097-Mar-02 00:00 23 51 45.60 +24 40 11.7 48.61 446.2560672260 26.2696723
2097-Sep-01 00:00 23 52 04.97 +24 48 15.0 48.63 449.0324857663 26.2703844
2098-Mar-03 00:00 23 51 45.71 +24 40 18.3 48.66 451.8087176126 26.2716587
2098-Sep-02 00:00 23 52 04.09 +24 48 13.1 48.68 454.5854073946 26.2736797
2099-Mar-04 00:00 23 51 45.80 +24 40 24.4 48.72 457.3620210856 26.2758314
2099-Sep-03 00:00 23 52 03.21 +24 48 10.8 48.74 460.1391793005 26.2783048
2100-Mar-05 00:00 23 51 45.88 +24 40 30.1 48.77 462.9163092806 26.2806896
2100-Sep-04 00:00 23 52 02.35 +24 48 08.3 48.79 465.6940016740 26.2832937
2101-Mar-06 00:00 23 51 45.97 +24 40 35.4 48.82 468.4716483939 26.2855656
2101-Sep-05 00:00 23 52 01.53 +24 48 05.6 48.84 471.2498134738 26.2875956
2102-Mar-07 00:00 23 51 46.08 +24 40 40.7 48.87 474.0278568717 26.2888765
2102-Sep-06 00:00 23 52 00.76 +24 48 03.1 48.89 476.8063215535 26.2897021
2103-Mar-08 00:00 23 51 46.24 +24 40 46.0 48.92 479.5845365105 26.2897072
2103-Sep-07 00:00 23 52 00.05 +24 48 00.7 48.94 482.3630197312 26.2891443
2104-Mar-08 00:00 23 51 46.43 +24 40 51.4 48.97 485.1410794424 26.2875876
2104-Sep-07 00:00 23 51 59.39 +24 47 58.7 48.99 487.9192381246 26.2853353
2105-Mar-09 00:00 23 51 46.65 +24 40 57.1 49.02 490.6968133300 26.2821900
2105-Sep-08 00:00 23 51 58.77 +24 47 57.0 49.04 493.4743527262 26.2787755
2106-Mar-10 00:00 23 51 46.88 +24 41 03.0 49.07 496.2512093005 26.2751210
2106-Sep-09 00:00 23 51 58.16 +24 47 55.6 49.08 499.0279908145 26.2717729
2107-Mar-11 00:00 23 51 47.09 +24 41 09.1 49.11 501.8041110989 26.2685871
2107-Sep-10 00:00 23 51 57.55 +24 47 54.3 49.13 504.5802409108 26.2660913
2108-Mar-11 00:00 23 51 47.27 +24 41 15.0 49.16 507.3558400948 26.2642288
2108-Sep-10 00:00 23 51 56.91 +24 47 53.0 49.18 510.1316121800 26.2634340
2109-Mar-12 00:00 23 51 47.42 +24 41 20.7 49.21 512.9070210537 26.2633402
2109-Sep-11 00:00 23 51 56.25 +24 47 51.4 49.23 515.6827674142 26.2640801
2110-Mar-13 00:00 23 51 47.52 +24 41 26.1 49.26 518.4583011834 26.2651943
2110-Sep-12 00:00 23 51 55.58 +24 47 49.6 49.27 521.2343053782 26.2668710
2111-Mar-14 00:00 23 51 47.62 +24 41 31.1 49.30 524.0101933775 26.2687672
2111-Sep-13 00:00 23 51 54.92 +24 47 47.5 49.32 526.7866151287 26.2710698
2112-Mar-14 00:00 23 51 47.70 +24 41 35.8 49.35 529.5629516554 26.2732699
2112-Sep-13 00:00 23 51 54.27 +24 47 45.3 49.36 532.3398291243 26.2753969
2113-Mar-15 00:00 23 51 47.80 +24 41 40.4 49.39 535.1165962531 26.2770413
2113-Sep-14 00:00 23 51 53.65 +24 47 43.0 49.41 537.8938521977 26.2784625
2114-Mar-16 00:00 23 51 47.92 +24 41 44.9 49.44 540.6709136313 26.2793283
2114-Sep-15 00:00 23 51 53.08 +24 47 40.8 49.45 543.4483523707 26.2797139
2115-Mar-17 00:00 23 51 48.08 +24 41 49.5 49.48 546.2254569839 26.2791708
2115-Sep-16 00:00 23 51 52.55 +24 47 38.9 49.50 549.0027868624 26.2778808
2116-Mar-17 00:00 23 51 48.26 +24 41 54.2 49.52 551.7796202594 26.2756504
2116-Sep-16 00:00 23 51 52.06 +24 47 37.2 49.54 554.5565143382 26.2728739
2117-Mar-18 00:00 23 51 48.46 +24 41 59.2 49.57 557.3327542246 26.2694791
2117-Sep-17 00:00 23 51 51.59 +24 47 35.9 49.58 560.1089334275 26.2658555
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Explorer1
post Oct 30 2017, 05:54 PM
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If only it had been noticed earlier, before closest approach... At any rate, a good argument for more wide field observations, even if interception remains implausible for this particular body.
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HSchirmer
post Oct 30 2017, 06:07 PM
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QUOTE (TheAnt @ Oct 30 2017, 04:08 PM) *
I agree in full about the value of getting such a sample, it would add to the knowledge about our own Kupier or Oort belt also.
And that was the reason I did that back-of-envelope type of calculation.
Only to find that a sample return would require a spacecraft of Frankensteinian proportions, so for several reasons not within a magnitude of our current capabilities.


Curious, getting a sample doesn't necessarily mean matching velocity, does it?
"Sample return" could be as simple as something crossing the projected path.

If we do get enough lead time in the future, are there any protocols about a obtaining a "reverse kinetic" sample?
That is, launch a 10kg steel manhole cover into the path of our 50,000 km/s visitor, kaboom, and then analyzing the debris?
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TheAnt
post Oct 30 2017, 07:47 PM
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QUOTE (HSchirmer @ Oct 30 2017, 07:07 PM) *
Curious, getting a sample doesn't necessarily mean matching velocity, does it?
"Sample return" could be as simple as something crossing the projected path.


Well my idea for the cubesat sized craft where one would collide would be for only getting a spectra of the gas and flash of the collision.

But yes sample return might be remotely possible, lets imagine the impacting cubesat is basically a ceramic brick with only a minimum of controlling electronics and miniature thrusters.
Then other cubesat's that fly in formation might have a piece of aerogel on one or several sides.
None of the cubesat's will have any significant propulsion on its own as they would be KISS devices.
But if the trajectory is planned well and it need to be - as any part of the small craft would be literally vaporized by any +20km/s impact -and that would be game over.
Celestial mechanics would eventually bring the cubesat or the aerogel parts back to the vicinity of Earth - for retrieval by another craft.
Now this is again wild speculation, and I guess the real pro's here can poke as many holes in this idea that it look like swizz cheese. =)
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HSchirmer
post Oct 30 2017, 10:13 PM
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QUOTE (TheAnt @ Oct 30 2017, 08:47 PM) *
I guess the real pro's here can poke as many holes in this idea that it look like swizz cheese. =)


Following up on that - here's a stupid question-
Why isn't this comet falling into the sun?
How likely (or unlikely) are hyperbolic path, parabolic path, orbit, or crash?


I understand that Kuiper and Oort objects start with angular momentum, which you can't get rid of, so they just don't "fall into the sun"
But, our other interstellar visitors don't start in orbit, so, what's the likelihood that they miss the sun?

In retrospect, it may be a fundamental property of orbits, the number of possible paths through the "hill sphere" of gravitational influence is is always going to be much larger than the number of possible paths that impact the object,
but are there any empirical calculations of how likely a parabolic orbit is, compared to a collision?
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fredk
post Oct 30 2017, 10:36 PM
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It just depends on the velocity distribution of interstellar objects. If it really is interstellar, and so unbound to the sun, then that just means it's got a hyperbolic or (borderline bound) parabolic orbit. Closed orbit means bound, so not interstellar (barring having been perturbed by another body to become bound).

The boundary (parabolic) means it approaches zero velocity (relative to the sun) at large distances. The velocity distribution of interstellar objects is going to be broad, certainly not peaked near zero, so generically you'd expect them to come in on hyperbolic orbits.

And collisions are going to be rare - the sun's a tiny target on the interstellar (or even solar system) scale. Again, generically the objects will have angular momentum relative to the sun - it would take fine-tuning (ie dead-centre collision) for them to have zero angular momentum.
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ngunn
post Oct 31 2017, 12:21 AM
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I'd like to know the miss distance of its approach trajectory, in other words the distance from the sun to the asymptote of the orbit. If my mental estimate is about right there must be about a thousand of these things passing though the orbit of Neptune every few years.
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fredk
post Oct 31 2017, 12:46 AM
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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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JRehling
post Oct 31 2017, 06:25 PM
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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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HSchirmer
post Oct 31 2017, 07:08 PM
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QUOTE (ngunn @ Oct 31 2017, 01:21 AM) *
I'd like to know the miss distance of its approach trajectory, in other words the distance from the sun to the asymptote of the orbit. If my mental estimate is about right there must be about a thousand of these things passing though the orbit of Neptune every few years.


I'm curious whether the outbound path will take it anywhere near VGR1, VGR2 or New Horizons...
Also curious to know whether any heliopause measurements detected any shockwave or disturbance when this thing was inbound,
which might help identify what happens when it passes back out of sol-space to interstellar-space on the outbound trajectory.

Fun tangent - is there a theoretical maximum for speed from gravity assist orbits?
Say, hypothetically, we launch a ion-engine probe so that it gets a gravity assist ▲v from the moon, breaks earth orbit and heads for the Sun and Mercury.
Gravity assist from the Sun kicks in huge ▲v and gravity assist from Mercury aims it back towards the moon.
Gravity assist from the moon kicks in more ▲v and sends it back towards the Sun and Mercury.
Repeat as necessary.
Using 2 large airless bodies to "play catch" and get repeated gravity assists from a star, how fast can you get?
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