IRIDIUM 155
Iridiumlaunched 2018low orbitNORAD 43573 · 2018-061E
- Height
- 801.8 km
- From center
- 7,164.4 km
- Sunlight
- Sunlit
- Speed
- 7.451 km/s
- Ground speed
- 6.592 km/s
- Over
- 58.677° S, 62.631° W
Passes
Known downlinks
No downlink frequencies are on file for this satellite. You can type one into the radio chart.
Elements are 13 hours old, from CelesTrak GP data (groups: active), fetched 3 h ago.
Technical details
Mean elements
Elements are 13 hours old, from CelesTrak GP data (groups: active), fetched 3 h ago.How accurate is this?
- Perigee
- 773 km
- Apogee
- 776 km
- Period
- 100.34 min
- Inclination
- 86.40°
- Eccentricity
- 0.0002204
- Semi-major axis
- 7,152.8 km
- Epoch
- 2026-11-15T10:32:10Z
Orbit check
The live speed and distance fit this orbit to within 0.059%.
Vis-viva: v²r/GM = 0.9978 and 2 − r/a = 0.9984
Raw elements
2LE
1 43573U 18061E 26319.43901022 .00000195 00000+0 62572-4 0 9990 2 43573 86.3977 353.4478 0002204 94.0742 266.0706 14.34218175435030
3LE
IRIDIUM 155 1 43573U 18061E 26319.43901022 .00000195 00000+0 62572-4 0 9990 2 43573 86.3977 353.4478 0002204 94.0742 266.0706 14.34218175435030
OMM
{
"OBJECT_NAME": "IRIDIUM 155",
"OBJECT_ID": "2018-061E",
"EPOCH": "2026-11-15T10:32:10.483872",
"MEAN_MOTION": 14.34218175,
"ECCENTRICITY": 0.0002204,
"INCLINATION": 86.3977,
"RA_OF_ASC_NODE": 353.4478,
"ARG_OF_PERICENTER": 94.0742,
"MEAN_ANOMALY": 266.0706,
"EPHEMERIS_TYPE": 0,
"CLASSIFICATION_TYPE": "U",
"NORAD_CAT_ID": 43573,
"ELEMENT_SET_NO": 999,
"REV_AT_EPOCH": 43503,
"BSTAR": 0.000062572,
"MEAN_MOTION_DOT": 0.00000195,
"MEAN_MOTION_DDOT": 0
}How we compute these
- Altitude
- Height above the WGS84 ellipsoid, the standard model of Earth's shape, straight below the satellite.
- Speed
- The length of SGP4's velocity vector in the TEME frame: the inertial speed. It is not the speed over the ground.
- Ground speed
- How fast the point below the satellite moves across Earth's surface, with Earth's rotation taken out.
- From Earth's center
- Distance from Earth's center, from SGP4's position.
- Latitude and longitude
- The point on the WGS84 ellipsoid straight below the satellite, from SGP4's position turned into Earth-fixed coordinates.
- Sunlight
- How much sunlight reaches the satellite past Earth and its atmosphere. Light grazing Earth is dimmed by air and ozone, bent into the shadow by refraction, and blocked below 10 km (clouds and haze); the Sun's disc is darker at its edge. So the satellite fades over a few seconds in low orbit and a couple of minutes in geostationary orbit, reddening as it goes, rather than switching off. The atmosphere is a clear standard one: haze from a large volcanic eruption can make the real fade come a few seconds early.
- Orbit check (vis-viva)
- v²r/GM uses the live speed and distance above, with GM = 398,600.4418 km³/s². Vis-viva says it equals 2 − r/a, where a is the mean semi-major axis. They agree as closely as SGP4's mean elements allow, usually within 1%.
- Mean elements
- Perigee, apogee, period, eccentricity, inclination and semi-major axis are mean elements from the published set, not instantaneous values. Perigee and apogee heights are above Earth's equatorial radius (6,378 km).
- Epoch
- The epoch is the moment the element set describes. Positions get less accurate the further you are from it.
- How accurate is this?
- Positions are predictions from the published elements, not live tracking. Through SGP4 they are usually within a kilometre or two near the epoch and drift by a few km a day after it, more for low or manoeuvring satellites. The map shows ground positions, the point straight below the satellite, so dots that look close can be thousands of km apart in height. Good for passes and tracks; not for judging close approaches between objects.