Topics

another natural satellite of Earth... again.


Sam Deen
 

Hi all,

I'm surprised I didn't notice this any sooner, but a friend pointed out to me that the recently-discovered asteroid 2020 SO is on an orbit that, while not currently orbiting us, will be captured into Earth orbit for a few months later this year.

Current geocentric orbit:

Perigee 2020 Nov 3.251863 +/- 0.0224 TT = 6:02:41 (JD 2459156.751863)
Epoch 2020 Sep 18.0 TT = JDT 2459110.5 Find_Orb
q707812.420 +/- 2281 (J2000 equator)
H 28.3 G 0.15 Peri. 229.78793 +/- 0.10
Node 253.78959 +/- 0.0014
e 2.3556565 +/- 0.00905 Incl. 5.78461 +/- 0.0029
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Due to perturbations by the Moon, it will dip below e=1 on October 15th:

Perigee 2020 Nov 18.985389 +/- 0.0761 TT = 23:38:57 (JD 2459172.485389)
Epoch 2020 Oct 15.0 TT = JDT 2459137.5 Find_Orb
M 359.13451846 +/- 0.052 (J2000 equator)
n 0.02473837 +/- 0.0016 Peri. 344.83330 +/- 0.030
a 0.16830513 +/- 0.00725 Node 210.49792 +/- 0.0031
e 0.9989798 +/- 3.96e-5 Incl. 49.43843 +/- 0.026
P 39.84 H 28.3 G 0.15 U 8.4
q 25685.3859 +/- 123 Q 0.33643856 +/- 0.0165
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Then it will reach its first perigee on December 1, at which point the asteroid will peak at magnitude 14.0 (geocentric, it'll probably be higher from closer stations):

Perigee 2020 Dec 1.296073 +/- 0.182 TT = 7:06:20 (JD 2459184.796073)
Epoch 2020 Dec 1.3 TT = JDT 2459184.8 Find_Orb
M 0.01992107 +/- 1.3 (J2000 equator)
n 5.07228274 +/- 0.707 Peri. 176.20926 +/- 2.8
a724104.427 +/- 67503 Node 28.69067 +/- 0.45
e 0.9291863 +/- 0.000445 Incl. 34.04654 +/- 0.6
P 70.97d H 28.3 G 0.15 U 12.5
q 51276.5093 +/- 3999 Q 0.00933791 +/- 0.000683
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Then it will reach its second perigee on 3 February 2021, slightly higher and a fair bit more uncertain (at this point it will peak at magnitude 15.2):

Perigee 2021 Feb 3.752433 +/- 4.02 TT = 18:03:30 (JD 2459249.252433)
Epoch 2021 Feb 3.75 TT = JDT 2459249.25 Find_Orb
M 359.99300257 +/- 21 (J2000 equator)
n 2.87651669 +/- 0.739 Peri. 162.35558 +/- 8
a 0.00706480 +/- 0.00119 Node 27.66278 +/- 3.4
e 0.7963238 +/- 0.00654 Incl. 29.51607 +/- 0.29
P 125.15d H 28.3 G 0.15 U 12.5
q 215261.182 +/- 20314 Q 0.01269067 +/- 0.0015
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

At this point, it will make another close approach to the Moon combined with just generally being ejected beyond Earth's hill radius, at which point its eccentricity will quickly increase and it will formally leave earth orbit (e=1) again in late May 2020, nominally May 21:

Perigee 2021 Mar 30.423267 +/- 49.1 TT = 10:09:30 (JD 2459303.923267)
Epoch 2021 May 21.0 TT = JDT 2459355.5 Find_Orb
q857161.590 +/- 556064 (J2000 equator)
H 28.3 G 0.15 Peri. 289.48583 +/- 70
Node 357.23445 +/- 20
e 1.0282245 +/- 0.209 Incl. 30.51023 +/- 16
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Running back its close approaches to Earth (half out of curiosity, half to see if it's an old artsat) nothing particularly stands out. With its orbit up to present, it typically made close approaches to Earth every 18 years or so (so 2002, 1984, 1966, 1948, etc):

Perigee 2002 Apr 13.269629 +/- 27.3 TT = 6:28:15 (JD 2452377.769629)
Epoch 2002 Apr 13.28 TT = JDT 2452377.78 Find_Orb
q 0.05376521 +/- 0.00687 (J2000 equator)
H 28.3 G 0.15 Peri. 334.16949 +/- 0.55
Node 185.70790 +/- 12
e 20.1117748 +/- 1.4 Incl. 158.19267 +/- 0.29
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Perigee 1984 Apr 6.864302 +/- 20.8 TT = 20:44:35 (JD 2445797.364302)
Epoch 1984 Apr 6.6 TT = JDT 2445797.1 Find_Orb
q 0.05414741 +/- 0.0158 (J2000 equator)
H 28.3 G 0.15 Peri. 337.88104 +/- 0.7
Node 186.47086 +/- 17
e 19.5215486 +/- 2.64 Incl. 157.57057 +/- 55
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

It did, however, briefly nominally orbit Earth briefly in the 1960s:

Perigee 1966 Nov 9.304185 +/- 12.4 TT = 7:18:01 (JD 2439438.804185)
Epoch 1966 Nov 9.3 TT = JDT 2439438.8 Find_Orb
M 359.98843786 +/- 2100 (J2000 equator)
n 2.76250351 +/- Peri. 224.06218 +/- 51
a 0.00725787 +/- Node 36.30149 +/- 80
e 0.7800141 +/- 17248 Incl. 32.49146 +/- 7
P 130.31d H 28.3 G 0.15 U 17.4
q 238852.490 +/- 2.74e+7 Q 0.01291912 +/- 0.188
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Of course as you can see that approach is not very well constrained at all, but we can't rule it out. The only things to launch into heliocentric orbit during that time were (going backwards) Pioneer 6, Venera 3, Venera 2, Zond 3, and Luna 6, all in 1965, with nothing in 1966 or 1967. I think it's safe to say this object *most likely* isn't space debris. Furthermore thanks to its one-month observation arc it's possible to constrain its AMR to 0.023 +/- 0.035 m^2/kg- a very heavy spacecraft if not solid rock.

In summary: This 5-13 meter asteroid will be entering Earth orbit between October 15 this year and ~May 21 next year. It definitely hasn't been close relations with Earth since at least the mid 1960s, so is most likely natural.

~Sam


 

Dear Sam,

yes for this object at Sormano's Observatory we have computed
close encounters with Earth

http://www.brera.mi.astro.it/sormano/teca.html

and Moon

http://www.brera.mi.astro.it/sormano/tam.html

I computed a MOID of 0.013 AU (MPC give 0.016 AU) so this
data has not gave us a warning in a first time...strange...

Your elements are quite interesting, thank you

Cheers,
Francesco



--------------------------------------------------------
Francesco Manca

SORMANO ASTRONOMICAL OBSERVATORY (MPC code 587)
Localita' Colma del Piano
I-22030 Sormano (Co) - Italy
E-mail: obs.sormano@...
WWW: http://www.brera.mi.astro.it/sormano
--------------------------------------------------------


Alan Harris
 

Paul Chodas has tentatively identified this with the Surveyor 2 Centaur rocket body, launched on September 20, 1966.  The very low Earth encounter velocity (0.6 km/sec is even low for lunar ejecta, so it is unlikely it is a natural body, even lunar ejecta, more likely space junk.

Alan

On 9/20/2020 2:30 PM, Sam Deen via groups.io wrote:
Hi all,

I'm surprised I didn't notice this any sooner, but a friend pointed out to me that the recently-discovered asteroid 2020 SO is on an orbit that, while not currently orbiting us, will be captured into Earth orbit for a few months later this year.

Current geocentric orbit:

Perigee 2020 Nov 3.251863 +/- 0.0224 TT = 6:02:41 (JD 2459156.751863)
Epoch 2020 Sep 18.0 TT = JDT 2459110.5 Find_Orb
q707812.420 +/- 2281 (J2000 equator)
H 28.3 G 0.15 Peri. 229.78793 +/- 0.10
Node 253.78959 +/- 0.0014
e 2.3556565 +/- 0.00905 Incl. 5.78461 +/- 0.0029
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Due to perturbations by the Moon, it will dip below e=1 on October 15th:

Perigee 2020 Nov 18.985389 +/- 0.0761 TT = 23:38:57 (JD 2459172.485389)
Epoch 2020 Oct 15.0 TT = JDT 2459137.5 Find_Orb
M 359.13451846 +/- 0.052 (J2000 equator)
n 0.02473837 +/- 0.0016 Peri. 344.83330 +/- 0.030
a 0.16830513 +/- 0.00725 Node 210.49792 +/- 0.0031
e 0.9989798 +/- 3.96e-5 Incl. 49.43843 +/- 0.026
P 39.84 H 28.3 G 0.15 U 8.4
q 25685.3859 +/- 123 Q 0.33643856 +/- 0.0165
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Then it will reach its first perigee on December 1, at which point the asteroid will peak at magnitude 14.0 (geocentric, it'll probably be higher from closer stations):

Perigee 2020 Dec 1.296073 +/- 0.182 TT = 7:06:20 (JD 2459184.796073)
Epoch 2020 Dec 1.3 TT = JDT 2459184.8 Find_Orb
M 0.01992107 +/- 1.3 (J2000 equator)
n 5.07228274 +/- 0.707 Peri. 176.20926 +/- 2.8
a724104.427 +/- 67503 Node 28.69067 +/- 0.45
e 0.9291863 +/- 0.000445 Incl. 34.04654 +/- 0.6
P 70.97d H 28.3 G 0.15 U 12.5
q 51276.5093 +/- 3999 Q 0.00933791 +/- 0.000683
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Then it will reach its second perigee on 3 February 2021, slightly higher and a fair bit more uncertain (at this point it will peak at magnitude 15.2):

Perigee 2021 Feb 3.752433 +/- 4.02 TT = 18:03:30 (JD 2459249.252433)
Epoch 2021 Feb 3.75 TT = JDT 2459249.25 Find_Orb
M 359.99300257 +/- 21 (J2000 equator)
n 2.87651669 +/- 0.739 Peri. 162.35558 +/- 8
a 0.00706480 +/- 0.00119 Node 27.66278 +/- 3.4
e 0.7963238 +/- 0.00654 Incl. 29.51607 +/- 0.29
P 125.15d H 28.3 G 0.15 U 12.5
q 215261.182 +/- 20314 Q 0.01269067 +/- 0.0015
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

At this point, it will make another close approach to the Moon combined with just generally being ejected beyond Earth's hill radius, at which point its eccentricity will quickly increase and it will formally leave earth orbit (e=1) again in late May 2020, nominally May 21:

Perigee 2021 Mar 30.423267 +/- 49.1 TT = 10:09:30 (JD 2459303.923267)
Epoch 2021 May 21.0 TT = JDT 2459355.5 Find_Orb
q857161.590 +/- 556064 (J2000 equator)
H 28.3 G 0.15 Peri. 289.48583 +/- 70
Node 357.23445 +/- 20
e 1.0282245 +/- 0.209 Incl. 30.51023 +/- 16
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Running back its close approaches to Earth (half out of curiosity, half to see if it's an old artsat) nothing particularly stands out. With its orbit up to present, it typically made close approaches to Earth every 18 years or so (so 2002, 1984, 1966, 1948, etc):

Perigee 2002 Apr 13.269629 +/- 27.3 TT = 6:28:15 (JD 2452377.769629)
Epoch 2002 Apr 13.28 TT = JDT 2452377.78 Find_Orb
q 0.05376521 +/- 0.00687 (J2000 equator)
H 28.3 G 0.15 Peri. 334.16949 +/- 0.55
Node 185.70790 +/- 12
e 20.1117748 +/- 1.4 Incl. 158.19267 +/- 0.29
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Perigee 1984 Apr 6.864302 +/- 20.8 TT = 20:44:35 (JD 2445797.364302)
Epoch 1984 Apr 6.6 TT = JDT 2445797.1 Find_Orb
q 0.05414741 +/- 0.0158 (J2000 equator)
H 28.3 G 0.15 Peri. 337.88104 +/- 0.7
Node 186.47086 +/- 17
e 19.5215486 +/- 2.64 Incl. 157.57057 +/- 55
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

It did, however, briefly nominally orbit Earth briefly in the 1960s:

Perigee 1966 Nov 9.304185 +/- 12.4 TT = 7:18:01 (JD 2439438.804185)
Epoch 1966 Nov 9.3 TT = JDT 2439438.8 Find_Orb
M 359.98843786 +/- 2100 (J2000 equator)
n 2.76250351 +/- Peri. 224.06218 +/- 51
a 0.00725787 +/- Node 36.30149 +/- 80
e 0.7800141 +/- 17248 Incl. 32.49146 +/- 7
P 130.31d H 28.3 G 0.15 U 17.4
q 238852.490 +/- 2.74e+7 Q 0.01291912 +/- 0.188
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Of course as you can see that approach is not very well constrained at all, but we can't rule it out. The only things to launch into heliocentric orbit during that time were (going backwards) Pioneer 6, Venera 3, Venera 2, Zond 3, and Luna 6, all in 1965, with nothing in 1966 or 1967. I think it's safe to say this object *most likely* isn't space debris. Furthermore thanks to its one-month observation arc it's possible to constrain its AMR to 0.023 +/- 0.035 m^2/kg- a very heavy spacecraft if not solid rock.

In summary: This 5-13 meter asteroid will be entering Earth orbit between October 15 this year and ~May 21 next year. It definitely hasn't been close relations with Earth since at least the mid 1960s, so is most likely natural.

~Sam



--
Alan Harris harrisaw@...
4603 Orange Knoll Ave. 818-790-8291
La Canada, CA 91011


Sam Deen
 

It's a possibility, but I'm not sure. It has a very high lightcurve amplitude, and appears to probably be chaotically tumbling:

08-19: 22.15-23.00 (expected 23.16) (0.85 mag over 42.7 minutes/curve power >0.020 mag/min)
08-22: 22.01-22.89 (expected 23.01) (0.88 mag over 53.8 minutes/curve power >0.016 mag/min)
09-09: 21.52-22.38 (expected 22.00) (0.86 mag over 14.0 minutes/curve power >0.061 mag/min)
09-16: 21.71-21.74 (expected 21.58) (0.03 mag over 14.1 minutes/curve power >0.002 mag/min)
09-17: 22.31-22.45 (expected 21.63) (0.14 mag over 84.1 minutes/curve power >0.002 mag/min)
09-18: 21.2 -21.6 (expected 21.46) (0.4 mag over 24.0 minutes/curve power >0.017 mag/min)

~Sam

On Sunday, September 20, 2020, 02:46:57 PM MST, Alan Harris <harrisaw@...> wrote:


Paul Chodas has tentatively identified this with the Surveyor 2 Centaur
rocket body, launched on September 20, 1966.  The very low Earth
encounter velocity (0.6 km/sec is even low for lunar ejecta, so it is
unlikely it is a natural body, even lunar ejecta, more likely space junk.

Alan

On 9/20/2020 2:30 PM, Sam Deen via groups.io wrote:
> Hi all,
>
> I'm surprised I didn't notice this any sooner, but a friend pointed out to me that the recently-discovered asteroid 2020 SO is on an orbit that, while not currently orbiting us, will be captured into Earth orbit for a few months later this year.
>
> Current geocentric orbit:
>
>    Perigee 2020 Nov 3.251863 +/- 0.0224 TT =  6:02:41 (JD 2459156.751863)
> Epoch 2020 Sep 18.0 TT = JDT 2459110.5                        Find_Orb
> q707812.420 +/- 2281                (J2000 equator)
> H  28.3  G 0.15                    Peri.  229.78793 +/- 0.10
>                                      Node  253.78959 +/- 0.0014
> e  2.3556565 +/- 0.00905          Incl.    5.78461 +/- 0.0029
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Due to perturbations by the Moon, it will dip below e=1 on October 15th:
>
>    Perigee 2020 Nov 18.985389 +/- 0.0761 TT = 23:38:57 (JD 2459172.485389)
> Epoch 2020 Oct 15.0 TT = JDT 2459137.5                        Find_Orb
> M 359.13451846 +/- 0.052            (J2000 equator)
> n  0.02473837 +/- 0.0016          Peri.  344.83330 +/- 0.030
> a  0.16830513 +/- 0.00725          Node  210.49792 +/- 0.0031
> e  0.9989798 +/- 3.96e-5          Incl.  49.43843 +/- 0.026
> P  39.84                  H 28.3  G  0.15  U  8.4
> q 25685.3859 +/- 123    Q 0.33643856 +/- 0.0165
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Then it will reach its first perigee on December 1, at which point the asteroid will peak at magnitude 14.0 (geocentric, it'll probably be higher from closer stations):
>
>    Perigee 2020 Dec 1.296073 +/- 0.182 TT =  7:06:20 (JD 2459184.796073)
> Epoch 2020 Dec  1.3 TT = JDT 2459184.8                        Find_Orb
> M  0.01992107 +/- 1.3              (J2000 equator)
> n  5.07228274 +/- 0.707            Peri.  176.20926 +/- 2.8
> a724104.427 +/- 67503              Node    28.69067 +/- 0.45
> e  0.9291863 +/- 0.000445          Incl.  34.04654 +/- 0.6
> P  70.97d                  H 28.3  G  0.15  U 12.5
> q 51276.5093 +/- 3999    Q 0.00933791 +/- 0.000683
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Then it will reach its second perigee on 3 February 2021, slightly higher and a fair bit more uncertain (at this point it will peak at magnitude 15.2):
>
>    Perigee 2021 Feb 3.752433 +/- 4.02 TT = 18:03:30 (JD 2459249.252433)
> Epoch 2021 Feb  3.75 TT = JDT 2459249.25                      Find_Orb
> M 359.99300257 +/- 21              (J2000 equator)
> n  2.87651669 +/- 0.739            Peri.  162.35558 +/- 8
> a  0.00706480 +/- 0.00119          Node    27.66278 +/- 3.4
> e  0.7963238 +/- 0.00654          Incl.  29.51607 +/- 0.29
> P 125.15d                  H 28.3  G  0.15  U 12.5
> q 215261.182 +/- 20314    Q 0.01269067 +/- 0.0015
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> At this point, it will make another close approach to the Moon combined with just generally being ejected beyond Earth's hill radius, at which point its eccentricity will quickly increase and it will formally leave earth orbit (e=1) again in late May 2020, nominally May 21:
>
>      Perigee 2021 Mar 30.423267 +/- 49.1 TT = 10:09:30 (JD 2459303.923267)
> Epoch 2021 May 21.0 TT = JDT 2459355.5                        Find_Orb
> q857161.590 +/- 556064              (J2000 equator)
> H  28.3  G 0.15                    Peri.  289.48583 +/- 70
>                                      Node  357.23445 +/- 20
> e  1.0282245 +/- 0.209            Incl.  30.51023 +/- 16
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Running back its close approaches to Earth (half out of curiosity, half to see if it's an old artsat) nothing particularly stands out. With its orbit up to present, it typically made close approaches to Earth every 18 years or so (so 2002, 1984, 1966, 1948, etc):
>
>    Perigee 2002 Apr 13.269629 +/- 27.3 TT =  6:28:15 (JD 2452377.769629)
> Epoch 2002 Apr 13.28 TT = JDT 2452377.78                      Find_Orb
> q  0.05376521 +/- 0.00687          (J2000 equator)
> H  28.3  G 0.15                    Peri.  334.16949 +/- 0.55
>                                      Node  185.70790 +/- 12
> e  20.1117748 +/- 1.4              Incl.  158.19267 +/- 0.29
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
>    Perigee 1984 Apr 6.864302 +/- 20.8 TT = 20:44:35 (JD 2445797.364302)
> Epoch 1984 Apr  6.6 TT = JDT 2445797.1                        Find_Orb
> q  0.05414741 +/- 0.0158          (J2000 equator)
> H  28.3  G 0.15                    Peri.  337.88104 +/- 0.7
>                                      Node  186.47086 +/- 17
> e  19.5215486 +/- 2.64              Incl.  157.57057 +/- 55
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> It did, however, briefly nominally orbit Earth briefly in the 1960s:
>
>    Perigee 1966 Nov 9.304185 +/- 12.4 TT =  7:18:01 (JD 2439438.804185)
> Epoch 1966 Nov  9.3 TT = JDT 2439438.8                        Find_Orb
> M 359.98843786 +/- 2100            (J2000 equator)
> n  2.76250351 +/-                  Peri.  224.06218 +/- 51
> a  0.00725787 +/-                  Node    36.30149 +/- 80
> e  0.7800141 +/- 17248            Incl.  32.49146 +/- 7
> P 130.31d                  H 28.3  G  0.15  U 17.4
> q 238852.490 +/- 2.74e+7    Q 0.01291912 +/- 0.188
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Of course as you can see that approach is not very well constrained at all, but we can't rule it out. The only things to launch into heliocentric orbit during that time were (going backwards) Pioneer 6, Venera 3, Venera 2, Zond 3, and Luna 6, all in 1965, with nothing in 1966 or 1967. I think it's safe to say this object *most likely* isn't space debris. Furthermore thanks to its one-month observation arc it's possible to constrain its AMR to 0.023 +/- 0.035 m^2/kg- a very heavy spacecraft if not solid rock.
>
> In summary: This 5-13 meter asteroid will be entering Earth orbit between October 15 this year and ~May 21 next year. It definitely hasn't been close relations with Earth since at least the mid 1960s, so is most likely natural.
>
> ~Sam

>
>
>
>
>
--
Alan Harris              harrisaw@...
4603 Orange Knoll Ave.  818-790-8291
La Canada, CA 91011







David Tholen
 

It has a very high lightcurve amplitude, and appears to probably be
chaotically tumbling
Isn't this behavior what one might expect from a long cylindrical
rocket body?


Sam Deen
 

Indeed, but it's also the behavior one would expect from a tiny monolithic asteroid as well, so impossible to say on that alone just yet.

~Sam

On Sunday, September 20, 2020, 03:37:54 PM MST, David Tholen <tholen@...> wrote:


> It has a very high lightcurve amplitude, and appears to probably be
> chaotically tumbling

Isn't this behavior what one might expect from a long cylindrical
rocket body?






Jonathan McDowell
 

Interesting. The orbital data for that Centaur were given to me by Don Lesney of General Dynamics:


On Sun, 20 Sep 2020 at 17:46, Alan Harris <harrisaw@...> wrote:
Paul Chodas has tentatively identified this with the Surveyor 2 Centaur
rocket body, launched on September 20, 1966.  The very low Earth
encounter velocity (0.6 km/sec is even low for lunar ejecta, so it is
unlikely it is a natural body, even lunar ejecta, more likely space junk.

Alan

On 9/20/2020 2:30 PM, Sam Deen via groups.io wrote:
> Hi all,
>
> I'm surprised I didn't notice this any sooner, but a friend pointed out to me that the recently-discovered asteroid 2020 SO is on an orbit that, while not currently orbiting us, will be captured into Earth orbit for a few months later this year.
>
> Current geocentric orbit:
>
>     Perigee 2020 Nov 3.251863 +/- 0.0224 TT =  6:02:41 (JD 2459156.751863)
> Epoch 2020 Sep 18.0 TT = JDT 2459110.5                        Find_Orb
> q707812.420 +/- 2281                (J2000 equator)
> H   28.3  G 0.15                    Peri.  229.78793 +/- 0.10
>                                      Node   253.78959 +/- 0.0014
> e   2.3556565 +/- 0.00905           Incl.    5.78461 +/- 0.0029
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Due to perturbations by the Moon, it will dip below e=1 on October 15th:
>
>     Perigee 2020 Nov 18.985389 +/- 0.0761 TT = 23:38:57 (JD 2459172.485389)
> Epoch 2020 Oct 15.0 TT = JDT 2459137.5                        Find_Orb
> M 359.13451846 +/- 0.052            (J2000 equator)
> n   0.02473837 +/- 0.0016           Peri.  344.83330 +/- 0.030
> a   0.16830513 +/- 0.00725          Node   210.49792 +/- 0.0031
> e   0.9989798 +/- 3.96e-5           Incl.   49.43843 +/- 0.026
> P  39.84                   H 28.3   G  0.15   U  8.4
> q 25685.3859 +/- 123    Q 0.33643856 +/- 0.0165
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Then it will reach its first perigee on December 1, at which point the asteroid will peak at magnitude 14.0 (geocentric, it'll probably be higher from closer stations):
>
>     Perigee 2020 Dec 1.296073 +/- 0.182 TT =  7:06:20 (JD 2459184.796073)
> Epoch 2020 Dec  1.3 TT = JDT 2459184.8                        Find_Orb
> M   0.01992107 +/- 1.3              (J2000 equator)
> n   5.07228274 +/- 0.707            Peri.  176.20926 +/- 2.8
> a724104.427 +/- 67503               Node    28.69067 +/- 0.45
> e   0.9291863 +/- 0.000445          Incl.   34.04654 +/- 0.6
> P  70.97d                  H 28.3   G  0.15   U 12.5
> q 51276.5093 +/- 3999    Q 0.00933791 +/- 0.000683
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Then it will reach its second perigee on 3 February 2021, slightly higher and a fair bit more uncertain (at this point it will peak at magnitude 15.2):
>
>     Perigee 2021 Feb 3.752433 +/- 4.02 TT = 18:03:30 (JD 2459249.252433)
> Epoch 2021 Feb  3.75 TT = JDT 2459249.25                      Find_Orb
> M 359.99300257 +/- 21               (J2000 equator)
> n   2.87651669 +/- 0.739            Peri.  162.35558 +/- 8
> a   0.00706480 +/- 0.00119          Node    27.66278 +/- 3.4
> e   0.7963238 +/- 0.00654           Incl.   29.51607 +/- 0.29
> P 125.15d                  H 28.3   G  0.15   U 12.5
> q 215261.182 +/- 20314    Q 0.01269067 +/- 0.0015
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> At this point, it will make another close approach to the Moon combined with just generally being ejected beyond Earth's hill radius, at which point its eccentricity will quickly increase and it will formally leave earth orbit (e=1) again in late May 2020, nominally May 21:
>
>      Perigee 2021 Mar 30.423267 +/- 49.1 TT = 10:09:30 (JD 2459303.923267)
> Epoch 2021 May 21.0 TT = JDT 2459355.5                        Find_Orb
> q857161.590 +/- 556064              (J2000 equator)
> H   28.3  G 0.15                    Peri.  289.48583 +/- 70
>                                      Node   357.23445 +/- 20
> e   1.0282245 +/- 0.209             Incl.   30.51023 +/- 16
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Running back its close approaches to Earth (half out of curiosity, half to see if it's an old artsat) nothing particularly stands out. With its orbit up to present, it typically made close approaches to Earth every 18 years or so (so 2002, 1984, 1966, 1948, etc):
>
>     Perigee 2002 Apr 13.269629 +/- 27.3 TT =  6:28:15 (JD 2452377.769629)
> Epoch 2002 Apr 13.28 TT = JDT 2452377.78                      Find_Orb
> q   0.05376521 +/- 0.00687          (J2000 equator)
> H   28.3  G 0.15                    Peri.  334.16949 +/- 0.55
>                                      Node   185.70790 +/- 12
> e  20.1117748 +/- 1.4               Incl.  158.19267 +/- 0.29
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
>     Perigee 1984 Apr 6.864302 +/- 20.8 TT = 20:44:35 (JD 2445797.364302)
> Epoch 1984 Apr  6.6 TT = JDT 2445797.1                        Find_Orb
> q   0.05414741 +/- 0.0158           (J2000 equator)
> H   28.3  G 0.15                    Peri.  337.88104 +/- 0.7
>                                      Node   186.47086 +/- 17
> e  19.5215486 +/- 2.64              Incl.  157.57057 +/- 55
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> It did, however, briefly nominally orbit Earth briefly in the 1960s:
>
>     Perigee 1966 Nov 9.304185 +/- 12.4 TT =  7:18:01 (JD 2439438.804185)
> Epoch 1966 Nov  9.3 TT = JDT 2439438.8                        Find_Orb
> M 359.98843786 +/- 2100             (J2000 equator)
> n   2.76250351 +/-                  Peri.  224.06218 +/- 51
> a   0.00725787 +/-                  Node    36.30149 +/- 80
> e   0.7800141 +/- 17248             Incl.   32.49146 +/- 7
> P 130.31d                  H 28.3   G  0.15   U 17.4
> q 238852.490 +/- 2.74e+7    Q 0.01291912 +/- 0.188
>  From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16
>
> Of course as you can see that approach is not very well constrained at all, but we can't rule it out. The only things to launch into heliocentric orbit during that time were (going backwards) Pioneer 6, Venera 3, Venera 2, Zond 3, and Luna 6, all in 1965, with nothing in 1966 or 1967. I think it's safe to say this object *most likely* isn't space debris. Furthermore thanks to its one-month observation arc it's possible to constrain its AMR to 0.023 +/- 0.035 m^2/kg- a very heavy spacecraft if not solid rock.
>
> In summary: This 5-13 meter asteroid will be entering Earth orbit between October 15 this year and ~May 21 next year. It definitely hasn't been close relations with Earth since at least the mid 1960s, so is most likely natural.
>
> ~Sam
>
>
>
>
>
--
Alan Harris              harrisaw@...
4603 Orange Knoll Ave.   818-790-8291
La Canada, CA 91011







tony873004
 

Here is my Twitter post. (You don't need a Twitter account to view it.)
It gives an animation, as well as a link to a simulation you can run in your browser.
It is in a rotating frame, so L1 & L2 are held stationary. This makes it easier to see the circumstances of capture and ejection.
Just like 2020 CD3, I expect each additional observation will radically change this very chaotic trajectory, so be careful about drawing any firm conclusions.

On Sun, Sep 20, 2020 at 2:31 PM Sam Deen via groups.io <planetaryscience=yahoo.com@groups.io> wrote:
Hi all,

I'm surprised I didn't notice this any sooner, but a friend pointed out to me that the recently-discovered asteroid 2020 SO is on an orbit that, while not currently orbiting us, will be captured into Earth orbit for a few months later this year.

Current geocentric orbit:

   Perigee 2020 Nov 3.251863 +/- 0.0224 TT =  6:02:41 (JD 2459156.751863)
Epoch 2020 Sep 18.0 TT = JDT 2459110.5                        Find_Orb
q707812.420 +/- 2281                (J2000 equator)
H   28.3  G 0.15                    Peri.  229.78793 +/- 0.10
                                    Node   253.78959 +/- 0.0014
e   2.3556565 +/- 0.00905           Incl.    5.78461 +/- 0.0029
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Due to perturbations by the Moon, it will dip below e=1 on October 15th:

   Perigee 2020 Nov 18.985389 +/- 0.0761 TT = 23:38:57 (JD 2459172.485389)
Epoch 2020 Oct 15.0 TT = JDT 2459137.5                        Find_Orb
M 359.13451846 +/- 0.052            (J2000 equator)
n   0.02473837 +/- 0.0016           Peri.  344.83330 +/- 0.030
a   0.16830513 +/- 0.00725          Node   210.49792 +/- 0.0031
e   0.9989798 +/- 3.96e-5           Incl.   49.43843 +/- 0.026
P  39.84                   H 28.3   G  0.15   U  8.4 
q 25685.3859 +/- 123    Q 0.33643856 +/- 0.0165
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Then it will reach its first perigee on December 1, at which point the asteroid will peak at magnitude 14.0 (geocentric, it'll probably be higher from closer stations):

   Perigee 2020 Dec 1.296073 +/- 0.182 TT =  7:06:20 (JD 2459184.796073)
Epoch 2020 Dec  1.3 TT = JDT 2459184.8                        Find_Orb
M   0.01992107 +/- 1.3              (J2000 equator)
n   5.07228274 +/- 0.707            Peri.  176.20926 +/- 2.8
a724104.427 +/- 67503               Node    28.69067 +/- 0.45
e   0.9291863 +/- 0.000445          Incl.   34.04654 +/- 0.6
P  70.97d                  H 28.3   G  0.15   U 12.5 
q 51276.5093 +/- 3999    Q 0.00933791 +/- 0.000683
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Then it will reach its second perigee on 3 February 2021, slightly higher and a fair bit more uncertain (at this point it will peak at magnitude 15.2):

   Perigee 2021 Feb 3.752433 +/- 4.02 TT = 18:03:30 (JD 2459249.252433)
Epoch 2021 Feb  3.75 TT = JDT 2459249.25                      Find_Orb
M 359.99300257 +/- 21               (J2000 equator)
n   2.87651669 +/- 0.739            Peri.  162.35558 +/- 8
a   0.00706480 +/- 0.00119          Node    27.66278 +/- 3.4
e   0.7963238 +/- 0.00654           Incl.   29.51607 +/- 0.29
P 125.15d                  H 28.3   G  0.15   U 12.5 
q 215261.182 +/- 20314    Q 0.01269067 +/- 0.0015
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

At this point, it will make another close approach to the Moon combined with just generally being ejected beyond Earth's hill radius, at which point its eccentricity will quickly increase and it will formally leave earth orbit (e=1) again in late May 2020, nominally May 21:

    Perigee 2021 Mar 30.423267 +/- 49.1 TT = 10:09:30 (JD 2459303.923267)
Epoch 2021 May 21.0 TT = JDT 2459355.5                        Find_Orb
q857161.590 +/- 556064              (J2000 equator)
H   28.3  G 0.15                    Peri.  289.48583 +/- 70
                                    Node   357.23445 +/- 20
e   1.0282245 +/- 0.209             Incl.   30.51023 +/- 16
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Running back its close approaches to Earth (half out of curiosity, half to see if it's an old artsat) nothing particularly stands out. With its orbit up to present, it typically made close approaches to Earth every 18 years or so (so 2002, 1984, 1966, 1948, etc):

   Perigee 2002 Apr 13.269629 +/- 27.3 TT =  6:28:15 (JD 2452377.769629)
Epoch 2002 Apr 13.28 TT = JDT 2452377.78                      Find_Orb
q   0.05376521 +/- 0.00687          (J2000 equator)
H   28.3  G 0.15                    Peri.  334.16949 +/- 0.55
                                    Node   185.70790 +/- 12
e  20.1117748 +/- 1.4               Incl.  158.19267 +/- 0.29
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

   Perigee 1984 Apr 6.864302 +/- 20.8 TT = 20:44:35 (JD 2445797.364302)
Epoch 1984 Apr  6.6 TT = JDT 2445797.1                        Find_Orb
q   0.05414741 +/- 0.0158           (J2000 equator)
H   28.3  G 0.15                    Peri.  337.88104 +/- 0.7
                                    Node   186.47086 +/- 17
e  19.5215486 +/- 2.64              Incl.  157.57057 +/- 55
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

It did, however, briefly nominally orbit Earth briefly in the 1960s:

   Perigee 1966 Nov 9.304185 +/- 12.4 TT =  7:18:01 (JD 2439438.804185)
Epoch 1966 Nov  9.3 TT = JDT 2439438.8                        Find_Orb
M 359.98843786 +/- 2100             (J2000 equator)
n   2.76250351 +/-                  Peri.  224.06218 +/- 51
a   0.00725787 +/-                  Node    36.30149 +/- 80
e   0.7800141 +/- 17248             Incl.   32.49146 +/- 7
P 130.31d                  H 28.3   G  0.15   U 17.4 
q 238852.490 +/- 2.74e+7    Q 0.01291912 +/- 0.188
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Of course as you can see that approach is not very well constrained at all, but we can't rule it out. The only things to launch into heliocentric orbit during that time were (going backwards) Pioneer 6, Venera 3, Venera 2, Zond 3, and Luna 6, all in 1965, with nothing in 1966 or 1967. I think it's safe to say this object *most likely* isn't space debris. Furthermore thanks to its one-month observation arc it's possible to constrain its AMR to 0.023 +/- 0.035 m^2/kg- a very heavy spacecraft if not solid rock.

In summary: This 5-13 meter asteroid will be entering Earth orbit between October 15 this year and ~May 21 next year. It definitely hasn't been close relations with Earth since at least the mid 1960s, so is most likely natural.

~Sam






tony873004
 

Assuming this the current elements are good enough to backwards integrate for a half-century, and assuming a gravity-only model is good enough to use on a rocket body, it last passed through the Earth/Moon system (about 0.1 Lunar Distance from Earth) in 1966, when its eccentricity WRT Earth also dropped below 0, agreeing with Alan and Paul that it may be artificial.


On Sun, Sep 20, 2020 at 5:11 PM tony873004 via groups.io <tony=gravitysimulator.com@groups.io> wrote:
Here is my Twitter post. (You don't need a Twitter account to view it.)
It gives an animation, as well as a link to a simulation you can run in your browser.
It is in a rotating frame, so L1 & L2 are held stationary. This makes it easier to see the circumstances of capture and ejection.
Just like 2020 CD3, I expect each additional observation will radically change this very chaotic trajectory, so be careful about drawing any firm conclusions.

On Sun, Sep 20, 2020 at 2:31 PM Sam Deen via groups.io <planetaryscience=yahoo.com@groups.io> wrote:
Hi all,

I'm surprised I didn't notice this any sooner, but a friend pointed out to me that the recently-discovered asteroid 2020 SO is on an orbit that, while not currently orbiting us, will be captured into Earth orbit for a few months later this year.

Current geocentric orbit:

   Perigee 2020 Nov 3.251863 +/- 0.0224 TT =  6:02:41 (JD 2459156.751863)
Epoch 2020 Sep 18.0 TT = JDT 2459110.5                        Find_Orb
q707812.420 +/- 2281                (J2000 equator)
H   28.3  G 0.15                    Peri.  229.78793 +/- 0.10
                                    Node   253.78959 +/- 0.0014
e   2.3556565 +/- 0.00905           Incl.    5.78461 +/- 0.0029
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Due to perturbations by the Moon, it will dip below e=1 on October 15th:

   Perigee 2020 Nov 18.985389 +/- 0.0761 TT = 23:38:57 (JD 2459172.485389)
Epoch 2020 Oct 15.0 TT = JDT 2459137.5                        Find_Orb
M 359.13451846 +/- 0.052            (J2000 equator)
n   0.02473837 +/- 0.0016           Peri.  344.83330 +/- 0.030
a   0.16830513 +/- 0.00725          Node   210.49792 +/- 0.0031
e   0.9989798 +/- 3.96e-5           Incl.   49.43843 +/- 0.026
P  39.84                   H 28.3   G  0.15   U  8.4 
q 25685.3859 +/- 123    Q 0.33643856 +/- 0.0165
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Then it will reach its first perigee on December 1, at which point the asteroid will peak at magnitude 14.0 (geocentric, it'll probably be higher from closer stations):

   Perigee 2020 Dec 1.296073 +/- 0.182 TT =  7:06:20 (JD 2459184.796073)
Epoch 2020 Dec  1.3 TT = JDT 2459184.8                        Find_Orb
M   0.01992107 +/- 1.3              (J2000 equator)
n   5.07228274 +/- 0.707            Peri.  176.20926 +/- 2.8
a724104.427 +/- 67503               Node    28.69067 +/- 0.45
e   0.9291863 +/- 0.000445          Incl.   34.04654 +/- 0.6
P  70.97d                  H 28.3   G  0.15   U 12.5 
q 51276.5093 +/- 3999    Q 0.00933791 +/- 0.000683
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Then it will reach its second perigee on 3 February 2021, slightly higher and a fair bit more uncertain (at this point it will peak at magnitude 15.2):

   Perigee 2021 Feb 3.752433 +/- 4.02 TT = 18:03:30 (JD 2459249.252433)
Epoch 2021 Feb  3.75 TT = JDT 2459249.25                      Find_Orb
M 359.99300257 +/- 21               (J2000 equator)
n   2.87651669 +/- 0.739            Peri.  162.35558 +/- 8
a   0.00706480 +/- 0.00119          Node    27.66278 +/- 3.4
e   0.7963238 +/- 0.00654           Incl.   29.51607 +/- 0.29
P 125.15d                  H 28.3   G  0.15   U 12.5 
q 215261.182 +/- 20314    Q 0.01269067 +/- 0.0015
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

At this point, it will make another close approach to the Moon combined with just generally being ejected beyond Earth's hill radius, at which point its eccentricity will quickly increase and it will formally leave earth orbit (e=1) again in late May 2020, nominally May 21:

    Perigee 2021 Mar 30.423267 +/- 49.1 TT = 10:09:30 (JD 2459303.923267)
Epoch 2021 May 21.0 TT = JDT 2459355.5                        Find_Orb
q857161.590 +/- 556064              (J2000 equator)
H   28.3  G 0.15                    Peri.  289.48583 +/- 70
                                    Node   357.23445 +/- 20
e   1.0282245 +/- 0.209             Incl.   30.51023 +/- 16
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Running back its close approaches to Earth (half out of curiosity, half to see if it's an old artsat) nothing particularly stands out. With its orbit up to present, it typically made close approaches to Earth every 18 years or so (so 2002, 1984, 1966, 1948, etc):

   Perigee 2002 Apr 13.269629 +/- 27.3 TT =  6:28:15 (JD 2452377.769629)
Epoch 2002 Apr 13.28 TT = JDT 2452377.78                      Find_Orb
q   0.05376521 +/- 0.00687          (J2000 equator)
H   28.3  G 0.15                    Peri.  334.16949 +/- 0.55
                                    Node   185.70790 +/- 12
e  20.1117748 +/- 1.4               Incl.  158.19267 +/- 0.29
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

   Perigee 1984 Apr 6.864302 +/- 20.8 TT = 20:44:35 (JD 2445797.364302)
Epoch 1984 Apr  6.6 TT = JDT 2445797.1                        Find_Orb
q   0.05414741 +/- 0.0158           (J2000 equator)
H   28.3  G 0.15                    Peri.  337.88104 +/- 0.7
                                    Node   186.47086 +/- 17
e  19.5215486 +/- 2.64              Incl.  157.57057 +/- 55
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

It did, however, briefly nominally orbit Earth briefly in the 1960s:

   Perigee 1966 Nov 9.304185 +/- 12.4 TT =  7:18:01 (JD 2439438.804185)
Epoch 1966 Nov  9.3 TT = JDT 2439438.8                        Find_Orb
M 359.98843786 +/- 2100             (J2000 equator)
n   2.76250351 +/-                  Peri.  224.06218 +/- 51
a   0.00725787 +/-                  Node    36.30149 +/- 80
e   0.7800141 +/- 17248             Incl.   32.49146 +/- 7
P 130.31d                  H 28.3   G  0.15   U 17.4 
q 238852.490 +/- 2.74e+7    Q 0.01291912 +/- 0.188
From 18 observations 2020 Aug. 19-Sept. 18; mean residual 0".16

Of course as you can see that approach is not very well constrained at all, but we can't rule it out. The only things to launch into heliocentric orbit during that time were (going backwards) Pioneer 6, Venera 3, Venera 2, Zond 3, and Luna 6, all in 1965, with nothing in 1966 or 1967. I think it's safe to say this object *most likely* isn't space debris. Furthermore thanks to its one-month observation arc it's possible to constrain its AMR to 0.023 +/- 0.035 m^2/kg- a very heavy spacecraft if not solid rock.

In summary: This 5-13 meter asteroid will be entering Earth orbit between October 15 this year and ~May 21 next year. It definitely hasn't been close relations with Earth since at least the mid 1960s, so is most likely natural.

~Sam






Bill J. Gray
 

Hi Sam,

I've been keeping an eye on this one for a bit now. I'm
reasonably sure that Paul Chodas has gotten this one right,
or at least that it's junk. (I'm not so confident that I'd
advise MPC to "de-designate" it, as they have for other objects
that turned out to be artificial, such as 2018 AV2 and 2010 KQ.
Until we detect definite signs of non-gravs, I will hold out
some hope that it's actually a rock. I'd find it interesting
either as "historic" space junk or as a temporarily captured
object, but my hopes are for the latter.)

But the hope is limited. As Alan points out, the low
Vinf is what you'd expect for junk, and not necessarily for
lunar ejecta. That's not a hard rule, but it does mean the
odds are against us. We also have a decent candidate object;
it doesn't take much of a tweak to the orbit to have 2020 SO
leaving the Earth-Moon system in late 1966. (Turn on all
perturbers and SRP, and constrain A=0.006.)

It does indeed look as if whatever it is, the object will
be temporarily captured, with a pass in early December and a
second one in February, and maybe even a pass or two after
that. But as Tony Dunn points out, we'll need more data
before having any confidence in that.

-- Bill

On 9/20/20 6:43 PM, Sam Deen via groups.io wrote:
Indeed, but it's also the behavior one would expect from a tiny monolithic asteroid as well, so impossible to say on that alone just yet.
~Sam
On Sunday, September 20, 2020, 03:37:54 PM MST, David Tholen <tholen@...> wrote:

> It has a very high lightcurve amplitude, and appears to probably be
> chaotically tumbling
Isn't this behavior what one might expect from a long cylindrical
rocket body?


andrew_j_walker@...
 

I've just noticed the JPL Small-Body Database Browser has added the 15 April 2002 event in
its list of close encounters (not on there yesterday). So the orbit is improving.

Andrew