PGDA - 50,000 LRO orbits

50,000 LRO orbits

Erwan Mazarico

The Lunar Reconnaissance Orbiter completed its 50,000th orbit around the Moon on August 1st, 2020 !

Launched on 19 June 2009, it inserted into orbit on June 23 2009. With a period just under two hours, it took more than 11 years to achieve this milestone.

Whether you are just curious about the orbit evolution over that time period or the geometry relevant to observations from any of its 7 scientific instruments, we compiled a large table of parameter values for these 50,000 orbits that would answer many requests.

While it is of course possible to get more fidelity or more specific information by using the LRO SPICE kernels directly (see here and here), through the NAIF toolkit or the online WebGeoCalc tool, we hope this table proves useful for the ‘easier’ queries.

The following links are to interactive plots that allow identifying time periods that match several kinds of geometry constraints. For more complex filtering, the full CSV table should be used.

- Orbit Number vs. Time

- Periapsis & Apoapsis Altitude vs. Time

- Periapsis Latitude vs. Time

- Earth (alpha) and Sun (beta) aspect angles vs. Time

- Orbit Inclination vs. Time

- Orbit Semi-Major Axis vs. Time

- Orbit Period vs. Time

- Argument of Periapsis vs. Time

- Moon Mean Anomaly vs. Time

- Latitude of Sun Occultations vs. Time

- Duration of Sun Occultations vs. Time

- Latitude of Earth Occultations vs. Time

- Duration of Earth Occultations vs. Time

The table is provided as a CSV (comma-separated values) ASCII file with one header line and 50,000 records, each with 70 parameters/values. These are detailed below.

==> Download the 34MB CSV file here. <==

Column Number	Parameter Name	Description	Unit	Parameter Block
01	OrbitNumber note that array index values for some programming languages like Python start at zero!	Orbit Number	-
02	OrbitSMA	Orbit semi-major axis	km	Orbit Keplerian Elements (osculating at ascending node)
03	OrbitEcc	Orbit eccentricity	-
04	OrbitInc	Orbit inclination	degrees
05	OrbitLonAscNode	Orbit longitude of ascending node	degrees
06	OrbitArgPeri	Orbit argument of periapsis	degrees
07	OrbitMeanAnom	Orbit mean anomaly (at ascending node)	degrees
08	OrbitPeriod	Orbit period	seconds
09	OrbitNormal_RAj2000	Inertial right ascension of orbit normal	degrees	Orbit Normal
10	OrbitNormal_DECj2000	Inertial declination of orbit normal	degrees	Orbit Normal
11	ET_AscNode	Time of ascending node	seconds	Position at ascending node
12	Lon_AscNode	Longitude of ascending node	degrees
13	Rad_AscNode	Radius at ascending node	km
14	ET_DescNode	Time of descending node	seconds	Position at descending node
15	Lon_DescNode	Longitude of descending node	degrees
16	Rad_DescNode	Radius at descending node	km
17	ET_Peri	Time of periapsis	seconds	Positoin at periapsis
18	Lon_Peri	Longitude of periapsis	degrees
19	Lat_Peri	Latitude at periapsis	degrees
20	Rad_Peri	Radius at periapsis	km
21	ET_Apo	Time of apoapsis	seconds	Positoin at apoapsis
22	Lon_Apo	Longitude of apoapsis	degrees
23	Lat_Apo	Latitude at apoapsis	degrees
24	Rad_Apo	Radius at apoapsis	km
25	ET_Northern	Time of northernmost point	seconds	Northernmost position
26	Lon_Northern	Longitude of northernmost point	degrees
27	Lat Northern	Latitude at northernmost point	degrees
28	Rad_Northern	Radius at northernmost point	km
29	ET_Southern	Time of southernmost point	seconds	Southerhmost positioin
30	Lon_Southern	Longitude of southernmost point	degrees
31	Lat_Southern	Latitude at southernmost point	degrees
32	Rad_Southern	Radius at southernmost point	km
33	Lon_Sun	Longitude of Sun	degrees	Sun geometry (at the time of ascending node)
34	Lat_Sun	Latitude of Sun	degrees
35	Rad_Sun	Distance to Sun	km
36	LST	Local Solar Time	Hours (0-24)
37	BetaAngle	Angle between orbit normal and Sun direction	degrees
38	Lon_Earth	Longitude of Sun	degrees	Earth geometry (at the time of ascending node)
39	Lat_Earth	Latitude of Sun	degrees
40	Rad_Earth	Distance to Sun	km
41	MeanAnomMoon	Mean anomaly of the Moon in its orbit around Earth	degrees
42	AlphaAngle	Angle between orbit normal and Earth direction	degrees
43	Duration_FullSun	Total duration during orbit when LRO sees the full Sun	seconds	Solar Illumination
44	Duration_PartialSun	Total duration during orbit when LRO sees the Sun (even partially)	seconds
45	Duration_NoSun	Total duration during orbit when LRO sees no Sun at all	seconds
46	Duration_ObscuredSun	Total duration during orbit when LRO does not see the full Sun	seconds
47	ET_IngressSun	Time (mid-point) of ingress occultation of the Sun	seconds	Sun Ingress Occultatioin
48	Duration_IngressSun	Duration of ingress occultation of the Sun	seconds
49	Lon_IngressSun	Longitude of LRO at (mid-point) of ingress occultation of the Sun	degrees
50	Lat_IngressSun	Latitude of LRO at (mid-point) of ingress occultation of the Sun	degrees
51	Rad_IngressSun	Radius of LRO at (mid-point) of ingress occultation of the Sun	km
52	ET_EgressSun	Time (mid-point) of egress occultation of the Sun	seconds	Sun Egress Occultatioin
53	Duration_EgressSun	Duration of egress occultation of the Sun	seconds
54	Lon_EgressSun	Longitude of LRO at (mid-point) of egress occultation of the Sun	degrees
55	Lat_EgressSun	Latitude of LRO at (mid-point) of egress occultation of the Sun	degrees
56	Rad_EgressSun	Radius of LRO at (mid-point) of egress occultation of the Sun	km
57	Duration_FullEarth	Total duration during orbit when LRO sees the full Earth	seconds	Earth Visibility
58	Duration_PartialEarth	Total duration during orbit when LRO sees the Earth (even partially)	seconds
59	Duration_NoEarth	Total duration during orbit when LRO sees no Earth at all	seconds
60	Duration_ObscuredEarth	Total duration during orbit when LRO does not see the full Sun	seconds
61	ET_IngressEarth	Time (mid-point) of egress occultation of the Earth	seconds	Earth Ingress Occultatioin
62	Duration_IngressEarth	Duration of egress occultation of the Earth	seconds
63	Lon_IngressEarth	Longitude of LRO at (mid-point) of egress occultation of the Earth	degrees
64	Lat_IngressEarth	Latitude of LRO at (mid-point) of ingress occultation of the Earth	degrees
65	Rad_IngressEarth	Radius of LRO at (mid-point) of ingress occultation of the Earth	km
66	ET_EgressEarth	Time (mid-point) of egress occultation of the Earth	seconds	Earth Egress Occultatioin
67	Duration_EgressEarth	Duration of egress occultation of the Earth	seconds
68	Lon_EgressEarth	Longitude of LRO at (mid-point) of egress occultation of the Earth	degrees
69	Lat_EgressEarth	Latitude of LRO at (mid-point) of egress occultation of the Earth	degrees
70	Rad_EgressEarth	Radius of LRO at (mid-point) of egress occultation of the Earth	km

Notes:

- an orbit is defined as starting at the ascending node (i.e., at equator crossing with latitude increasing).

- the times are given as Ephemeris Time (seconds since January 1, 2000, at 12:00 TT).

- longitudes and latitudes are given in the Moon-fixed frame (MOON_ME).

Product Keywords

LRO Moon orbit determination

NASA’s Planetary Geology, Geophysics and Geochemistry Laboratory

Goddard Space Flight Center

50,000 LRO orbits

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