ISS (ZARYA)
Space stationlaunched 1998low orbitvery brightNORAD 25544 · 1998-067A
The International Space Station: crewed without a break since 2000, and about as long as a football field.
- Height
- 438.9 km
- From center
- 6,804.0 km
- Sunlight
- Sunlit
- Speed
- 7.647 km/s
- Ground speed
- 6.865 km/s
- Over
- 51.661° S, 157.486° W
Passes
Known downlinks
- 437.800 MHz, FM cross-band repeater (on-demand)
Uplink 145.990 MHz FM, 67.0 Hz tone - 437.550 MHz, SSTV events (Robot 36), FM (scheduled)
- 145.800 MHz, Voice (crew contacts), older SSTV events, FM (scheduled)
Elements are 10 hours old, from CelesTrak GP data (groups: active, visual), fetched 2 h ago.
Technical details
Mean elements
Elements are 10 hours old, from CelesTrak GP data (groups: active, visual), fetched 2 h ago.How accurate is this?
- Perigee
- 414 km
- Apogee
- 424 km
- Period
- 92.95 min
- Inclination
- 51.63°
- Eccentricity
- 0.0007375
- Semi-major axis
- 6,797.1 km
- Epoch
- 2026-11-15T08:02:34Z
Orbit check
The live speed and distance fit this orbit to within 0.088%.
Vis-viva: v²r/GM = 0.9981 and 2 − r/a = 0.9990
Raw elements
2LE
1 25544U 98067A 26319.33511727 .00010226 00000+0 19082-3 0 9993 2 25544 51.6322 272.1219 0007375 28.0230 332.1155 15.49391288595180
3LE
ISS (ZARYA) 1 25544U 98067A 26319.33511727 .00010226 00000+0 19082-3 0 9993 2 25544 51.6322 272.1219 0007375 28.0230 332.1155 15.49391288595180
OMM
{
"OBJECT_NAME": "ISS (ZARYA)",
"OBJECT_ID": "1998-067A",
"EPOCH": "2026-11-15T08:02:34.132128",
"MEAN_MOTION": 15.49391288,
"ECCENTRICITY": 0.0007375,
"INCLINATION": 51.6322,
"RA_OF_ASC_NODE": 272.1219,
"ARG_OF_PERICENTER": 28.023,
"MEAN_ANOMALY": 332.1155,
"EPHEMERIS_TYPE": 0,
"CLASSIFICATION_TYPE": "U",
"NORAD_CAT_ID": 25544,
"ELEMENT_SET_NO": 999,
"REV_AT_EPOCH": 59518,
"BSTAR": 0.00019082,
"MEAN_MOTION_DOT": 0.00010226,
"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.