Current telemetry
Live ground track
Telemetry history
Altitude
-- kmCabin pressure
-- mmHgCabin temp
-- °CTotal mass
-- kgUrine tank
-- %Waste water
-- %Clean water
-- %How to read the station
Orbit and altitude
The ISS circles Earth about every 90 minutes at 400 to 420 km. Thin residual atmosphere slowly drags the orbit down, and periodic reboost burns push it back up. That sawtooth pattern, a slow decay followed by a sharp step, is the signature you will see in the altitude history above.
Cabin environment
The station keeps a shirt-sleeve environment: near sea-level pressure of about 760 mmHg and a temperature around 22 °C. The life support system holds these within tight bands, so even small excursions in the charts usually trace back to ordinary crew activity or equipment cycling.
Total mass
At roughly 420 metric tons, the station's mass still moves. Cargo ships and crew capsules add their mass when they dock and remove it when they leave. A step change in this trace almost always means a vehicle arrived or departed.
Water recovery
In Node 3, the water recovery system turns urine and cabin condensate back into drinking water, recovering most of what the crew uses. The three tank levels above show the loop in motion: urine waiting for processing, waste water queued for treatment, and clean water ready to drink.
If you want the longer story behind these numbers, the ISS Monitor blog covers reboosts, life support, and the history of the station in more depth.
Frequently asked questions
How high does the ISS fly, and why does its altitude keep changing?
The International Space Station orbits at roughly 400 to 420 km (249 to 261 mi) above Earth. Even at that height a trace of atmosphere remains, so drag slowly pulls the station down, typically by a couple of kilometers (about one mile) per month. Ground teams periodically fire thrusters on the station or on a docked cargo vehicle to raise the orbit again. On the altitude chart these reboosts show up as sharp upward steps, followed by a long, gentle decay.
What is normal cabin pressure and temperature on the ISS?
The cabin is kept close to sea-level conditions: about 760 mmHg (14.7 psi) of pressure with an Earth-like nitrogen and oxygen mix, and a temperature around 22 °C (72 °F). Crews can adjust the setpoint within roughly 18 to 27 °C (64 to 81 °F), so small day-to-day variations in the readout are completely normal.
Why does the total mass of the station change?
The ISS weighs on the order of 420,000 kg (about 926,000 lb), but that figure is not constant. Every arriving crew capsule or cargo ship adds its own mass, and every departure subtracts it. Supplies get consumed, trash gets loaded into departing vehicles and burned up on reentry. Watching the total mass jump is a simple way to spot dockings and undockings in the data.
What do the urine tank, waste water, and clean water levels mean?
They describe the station's water recovery system in the Node 3 module. Urine collects in a tank until the Urine Processor Assembly distills it. The output joins cabin condensate as waste water, which the Water Processor Assembly filters and treats into clean, drinkable water. The loop recovers roughly 90 to 98 percent of the water on board, which is what makes long missions practical without constant resupply.
Where does this data come from and how often does it update?
Cabin pressure, temperature, total mass, and the water tank levels come from the public NASA ISS Live telemetry stream (Lightstreamer, adapter ISSLIVE). Altitude and the map position are computed from the station's orbital elements (a TLE published by Celestrak) using the SGP4 model. A collector stores one sample per minute, and the map position refreshes every 10 seconds. ISS Monitor is an independent project and is not affiliated with NASA or any space agency.
Why do some charts have gaps?
The upstream telemetry feed occasionally drops out, for example during signal handovers between relay satellites or when NASA pauses the public stream. Some metrics also joined the archive later than others, so older history simply does not exist for them. Gaps are left visible rather than interpolated away.