"Pseudo-MPEC" for LCROSS
Created Sat Aug 08 09:12:59 2009 using Find_Orb
You can get ephemerides for this object from the Minor Planet Center's Distant Artificial Satellites Observation page, or from JPL's Horizons system, customized for your observing location and desired time span. The former is quicker and easier to use. The latter can give you some additional details the MPC doesn't supply. (The following ephemerides are geocentric, only suited for giving you a rough idea as to what's going on... and are no longer completely valid anyway, following the malfunction in late August.)
This shows LCROSS data for times after 22 July, when it made the maneuver that put it on course to hit the moon, and before the late August misfire. According to Horizons, the maneuver was made sometime around 21 July 13:00 UT. You can click here for pre-maneuver data, including elements near launch and the first lunar flyby; and you can click here for post-malfunction data.
As the impact elements show, the data were good enough to be used to compute an impact point on the moon (now no longer valid, of course). The arc was long enough to determine the effects of solar radiation pressure to within about +/- 15%, though, and the resulting area/mass ratio is presumably about as valid as it was before the malfunction.
Running some Monte Carlo orbits shows that the probability of impact is essentially 100%. With recent observations, the uncertainty area has shrunk a lot; click here for a map of the possible lunar impact area. You can see that the possible impact points, shown as big red triangles, are all in a (now short) line in the far southern hemisphere, all on the near side, a little past the terminator. If it were me doing it, I'd steer LCROSS to some place on the night side, but close enough to the terminator so that anything kicked up would enter sunlight quickly... which looks to be what's actually going on.
This NASA site states that "...the final site selection will be made 30 days prior to impact", so this is presumably not the last maneuver.
TLEs (Two-Line Elements) (updated 28 July): Some programs will allow one to display Earth-orbiting satellites using elements in the TLE format. Here are TLEs for LCROSS. The satellite model used for TLEs is really intended for low-earth, geosynchronous, or 12-hour satellites, and doesn't work over long time spans for LCROSS-like objects. To overcome this, I've provided elements for one-day intervals covering most of the LCROSS mission. Pick the elements corresponding to your date of interest. For that day only, the maximum error in kilometers will correspond to the 'Worst residual' shown for that day (usually about 60 kilometers, or less than an arcminute at the distance of LCROSS.) Use it outside that range, and things fall apart rapidly. Also, be warned that TLEs aren't provided for July 29 through August 6, nor after 6 October. The program I wrote to compute TLEs choked on those data, giving a divergent (completely meaningless) solution.
Astrometry:
LCROSS C2009 07 22.39253 23 49 15.02 -44 16 23.6 15.1 V D0269F85
LCROSS C2009 07 22.39374 23 49 17.75 -44 16 27.0 16.0 V D0269F85
LCROSS C2009 07 22.39493 23 49 20.52 -44 16 30.4 15.4 V D0269F85
LCROSS C2009 07 22.39608 23 49 23.21 -44 16 33.6 15.3 V D0269F85
LCROSS C2009 07 22.39738 23 49 26.30 -44 16 37.3 15.6 V D0269F85
LCROSS C2009 07 22.70781 00 02 02.07 -43 40 12.0 15.5 V D0269E12
LCROSS C2009 07 22.70812 00 02 02.58 -43 40 10.0 15.5 V D0269E12
LCROSS C2009 07 22.70841 00 02 03.04 -43 40 07.8 15.4 V D0269E12
LCROSS C2009 07 23.48510 00 41 23.84 -41 20 30.5 15.5 V D0270F84
LCROSS C2009 07 23.48672 00 41 26.72 -41 20 21.7 15.4 V D0270F84
LCROSS C2009 07 23.48779 00 41 28.63 -41 20 15.7 15.5 V D0270F84
LCROSS C2009 07 23.49003 00 41 32.57 -41 20 03.3 15.4 V D0270F84
LCROSS C2009 07 23.49110 00 41 34.46 -41 19 56.8 15.6 V D0270F84
LCROSS C2009 07 25.63233 02 15 46.13 -30 12 24.7 15.9 V D0271F85
LCROSS C2009 07 25.63660 02 15 50.95 -30 10 47.6 15.7 V D0271F85
LCROSS C2009 07 25.64063 02 15 55.52 -30 09 15.5 15.8 V D0271F85
LCROSS C2009 07 25.64535 02 16 00.81 -30 07 26.7 15.5 V D0271F85
LCROSS C2009 07 26.59644 02 56 28.50 -22 57 23.0 15.9 V D0272F85
LCROSS C2009 07 26.59865 02 56 31.30 -22 56 27.7 16.5 V D0272F85
LCROSS C2009 07 26.60084 02 56 34.02 -22 55 33.1 15.9 V D0272F85
LCROSS C2009 07 26.60301 02 56 36.70 -22 54 38.5 16.0 V D0272F85
LCROSS C2009 07 26.60530 02 56 39.52 -22 53 40.4 15.9 V D0272F85
LCROSS C2009 07 29.61699 04 57 40.86 +06 33 06.8 15.6 V D0273F85
LCROSS C2009 07 29.62093 04 57 47.65 +06 35 49.9 16.0 V D0273F85
LCROSS C2009 07 29.62477 04 57 54.20 +06 38 28.9 15.9 V D0273F85
LCROSS C2009 07 29.62875 04 58 00.82 +06 41 13.7 15.9 V D0273F85
LCROSS C2009 07 29.63304 04 58 07.89 +06 44 11.6 16.2 V D0273F85
LCROSS C2009 08 07.88135 14 21 08.81 +27 56 39.2 16.7 R D0280J95
LCROSS C2009 08 07.88295 14 21 11.58 +27 55 55.3 16.8 R D0280J95
LCROSS C2009 08 07.88457 14 21 14.37 +27 55 11.0 16.7 R D0280J95
Station data:
(E12) Siding Spring Survey (S31.2735 E149.0642). Observers R. H. McNaught,
S. Larson, et.al. Measurer R. H. McNaught. 0.5-m Uppsala Schmidt + CCD.
(F84) Hibiscus Observatory, Punaauia (S17.6341 W149.6158). Observer N.
Teamo. 0.35-m f/2.0 Schmidt + 1392x1040 CCD.
(F85) Tiki Observatory, Punaauia (S17.6341 W149.6158).
(J95) Great Shefford (N51.47497 W1.44700). Observer P. Birtwhistle. 0.30-m
f/6.3 Schmidt-Cassegrain + CCD.
Orbital elements:
LCROSS
Perigee 2009 Jul 31.837103 TT = 20:05:25 (JD 2455044.337103)
Epoch 2009 Jul 26.0 TT; AMR 0.014573 m2/kg Find_Orb
M 299.18106 (2000.0) P Q
n 10.41936939 Peri. 43.43860 -0.16856863 -0.72765907
a448100.967km Node 67.79497 0.58626972 -0.61628309
e 0.2032576 Incl. 45.90315 0.79238401 0.30117672
P 34.55d H 25.5 G 0.15 q 357021.024km Q 539180.911km
From 30 observations 2009 July 22-Aug. 7; RMS error 0.388 arcseconds
Orbital elements (impact):
LCROSS
Perilune 2009 Oct 9.496658 TT = 11:55:11 (JD 2455113.996658)
Epoch 2009 Oct 9.5 TT; AMR 0.014573 m^2/kg Find_Orb
q 129.290927km (2000.0) P Q
H 25.5 G 0.15 Peri. 69.47384 0.35375877 0.88245822
Node 341.89213 -0.41409741 -0.14945097
e 1.0165914 Incl. 85.96342 0.83867637 -0.44601781
From 30 observations 2009 July 22-Aug. 7; RMS error 0.388 arcseconds
IMPACT at 9 Oct 2009 11:45:24.70 lat -75.86165 lon 65.37749
Residuals in arcseconds:
090722 F85 .09+ .15- 090723 F84 .29+ .05- 090726 F85 .17- .41-
090722 F85 .79- .01- 090723 F84 .13+ .30- 090726 F85 .06- .21-
090722 F85 .60- .02+ 090723 F84 .27+ .05+ 090729 F85 .23- .05-
090722 F85 .17- .09+ 090725 F85 .28+ .20- 090729 F85 .25- .04-
090722 F85 1.0+ .03+ 090725 F85 .17- .32+ 090729 F85 .26+ .03+
090722 E12 .09- .21+ 090725 F85 .06+ .24+ 090729 F85 .16- .12+
090722 E12 .06- .31+ 090725 F85 .06- .19- 090729 F85 .16+ .52+
090722 E12 .23- .72+ 090726 F85 .10- .10- 090807 J95 .05+ .06+
090723 F84 .31+ .02- 090726 F85 .13+ .02- 090807 J95 .12+ .05-
090723 F84 .18+ .11- 090726 F85 .07- .36- 090807 J95 .15- .03+
Ephemerides:
Date (UT) RA Dec delta r elong mag
---- -- -- ------------ ------------ ------ ------ ----- ---
2009 08 01 06 53 56.750 +31 21 15.81 357871 1.0128 28.3 21.2
2009 08 02 08 00 57.109 +39 34 11.70 361863 1.0126 24.1 22.2
2009 08 03 09 19 07.945 +44 41 53.24 370444 1.0125 27.7 21.4
2009 08 04 10 41 20.462 +46 02 47.51 382742 1.0125 36.1 20.0
2009 08 05 11 56 34.853 +43 57 27.21 397642 1.0126 45.8 18.8
2009 08 06 12 58 39.259 +39 31 34.03 414009 1.0127 55.4 17.9
2009 08 07 13 47 55.352 +33 50 27.94 430833 1.0129 64.5 17.3
2009 08 08 14 27 22.151 +27 37 39.20 447290 1.0131 73.0 16.9
2009 08 09 14 59 55.914 +21 16 58.80 462754 1.0133 80.8 16.6
2009 08 10 15 27 49.813 +15 00 06.25 476777 1.0135 88.0 16.3
2009 08 11 15 52 38.426 +08 52 05.65 489056 1.0138 94.7 16.1
2009 08 12 16 15 29.701 +02 54 42.65 499402 1.0140 100.9 15.9
2009 08 13 16 37 14.890 -02 51 47.36 507718 1.0142 106.8 15.7
2009 08 14 16 58 35.543 -08 27 39.61 513970 1.0143 112.4 15.6
2009 08 15 17 20 08.392 -13 53 04.65 518173 1.0144 117.6 15.4
2009 08 16 17 42 28.935 -19 07 43.98 520379 1.0145 122.6 15.3
2009 08 17 18 06 14.234 -24 10 28.88 520656 1.0146 127.3 15.2
2009 08 18 18 32 05.085 -28 58 57.15 519090 1.0146 131.7 15.0
2009 08 19 19 00 47.237 -33 29 04.33 515770 1.0146 135.8 14.9
2009 08 20 19 33 10.526 -37 34 27.88 510792 1.0145 139.4 14.8
2009 08 21 20 10 03.560 -41 05 48.46 504258 1.0144 142.3 14.7
2009 08 22 20 52 00.495 -43 50 25.18 496280 1.0142 144.4 14.6
2009 08 23 21 38 58.270 -45 32 42.67 486992 1.0140 145.4 14.5
2009 08 24 22 29 52.215 -45 56 18.48 476558 1.0137 145.0 14.5
2009 08 25 23 22 32.894 -44 47 54.40 465182 1.0133 143.1 14.5
2009 08 26 00 14 23.671 -42 01 04.54 453119 1.0129 139.6 14.5
2009 08 27 01 03 20.380 -37 37 22.93 440679 1.0125 134.7 14.6
2009 08 28 01 48 28.064 -31 44 24.15 428245 1.0119 128.4 14.7
2009 08 29 02 29 57.750 -24 32 50.15 416266 1.0114 121.1 14.9
2009 08 30 03 08 43.648 -16 14 52.72 405261 1.0107 112.8 15.1
2009 08 31 03 46 03.546 -07 04 21.14 395798 1.0101 103.6 15.3
2009 09 01 04 23 30.159 +02 41 57.81 388457 1.0094 93.9 15.6
2009 09 02 05 02 51.599 +12 42 29.46 383773 1.0087 83.8 16.0
2009 09 03 05 46 15.672 +22 29 02.18 382163 1.0080 73.7 16.5
2009 09 04 06 36 07.694 +31 25 26.15 383850 1.0074 64.0 17.1
2009 09 05 07 34 38.029 +38 47 44.50 388828 1.0068 55.2 17.8
2009 09 06 08 42 04.294 +43 49 26.73 396853 1.0062 47.8 18.6
2009 09 07 09 54 37.613 +45 57 00.30 407498 1.0057 42.4 19.2
2009 09 08 11 04 52.602 +45 10 17.90 420216 1.0053 39.4 19.7
2009 09 09 12 06 29.980 +42 04 37.01 434417 1.0050 38.8 19.8
2009 09 10 12 57 31.680 +37 28 30.34 449528 1.0047 40.2 19.7
2009 09 11 13 39 09.980 +32 02 57.74 465024 1.0045 43.1 19.4
2009 09 12 14 13 34.218 +26 15 27.59 480453 1.0043 46.9 19.1
2009 09 13 14 42 43.263 +20 22 22.56 495428 1.0041 51.0 18.7
2009 09 14 15 08 09.368 +14 32 50.12 509629 1.0040 55.4 18.4
2009 09 15 15 31 00.895 +08 51 37.63 522788 1.0040 59.8 18.1
2009 09 16 15 52 08.728 +03 21 03.28 534680 1.0039 64.2 17.8
2009 09 17 16 12 11.949 -01 57 57.53 545112 1.0038 68.6 17.6
2009 09 18 16 31 42.058 -07 05 12.89 553922 1.0038 72.8 17.3
2009 09 19 16 51 06.044 -12 00 50.10 560969 1.0038 77.0 17.1
2009 09 20 17 10 48.668 -16 44 59.35 566135 1.0038 81.2 17.0
2009 09 21 17 31 14.267 -21 17 40.67 569323 1.0038 85.3 16.8
2009 09 22 17 52 48.250 -25 38 31.19 570457 1.0038 89.4 16.6
2009 09 23 18 15 58.332 -29 46 30.41 569474 1.0037 93.5 16.4
2009 09 24 18 41 15.426 -33 39 41.19 566320 1.0037 97.6 16.3
2009 09 25 19 09 13.874 -37 14 43.97 560942 1.0037 101.8 16.1
2009 09 26 19 40 30.424 -40 26 23.73 553288 1.0037 106.1 15.9
2009 09 27 20 15 40.520 -43 06 56.89 543343 1.0036 110.5 15.7
2009 09 28 20 55 09.136 -45 05 55.53 531176 1.0036 115.0 15.6
2009 09 29 21 38 54.479 -46 10 24.43 516966 1.0035 119.7 15.4
2009 09 30 22 26 10.534 -46 06 08.01 500988 1.0034 124.6 15.1
2009 10 01 23 15 23.413 -44 39 42.10 483603 1.0033 129.5 14.9
2009 10 02 00 04 33.985 -41 41 12.83 465264 1.0031 134.4 14.7
2009 10 03 00 51 58.662 -37 05 55.56 446531 1.0029 138.9 14.5
2009 10 04 01 36 41.618 -30 54 12.37 428092 1.0026 142.3 14.3
2009 10 05 02 18 41.898 -23 10 43.40 410763 1.0023 143.7 14.2
2009 10 06 02 58 42.608 -14 04 16.77 395473 1.0019 142.1 14.1
2009 10 07 03 37 57.737 -03 48 41.71 383217 1.0014 137.2 14.2
2009 10 08 04 18 04.803 +07 16 38.80 374974 1.0008 129.4 14.4
2009 10 09 05 00 57.399 +18 55 28.70 371751 1.0002 119.6 14.6
2009 10 10 06 11 16.327 +19 37 34.72 378610 0.9993 104.0 15.2