What is ISS-Tracking?
ISS-Tracking (iss-tracking.com) is an independent project built out of a passion for space exploration, with a simple goal: to make it visible and accessible, in real time and free of charge, where the International Space Station is right now and what's around it.
How does it work?
The ISS's current position comes from a public real-time API. The predicted trajectory line is calculated directly in your browser from the station's official orbital parameters (TLE), which refresh automatically so the prediction never goes stale. All the calculation happens on your own device, with no intermediate servers.
An independent project
ISS-Tracking is not affiliated with NASA, ESA, Roscosmos, or any space agency: it's a personal project, maintained by Adrián, with an interest in astronomy and web development. Data is provided for informational and educational purposes, not as an official source. More details in the Legal Notice.
Where does the data come from?
We generate no positional data of our own: everything you see comes from public sources, and each section uses its own. Here they are, plainly:
- Position, altitude and speed: the public API from WhereTheISS.at for satellite NORAD 25544, the ISS's official catalogue number. Polled every few seconds.
- Orbital parameters (TLE): the two-line elements published by CelesTrak and by WhereTheISS.at itself. These are the numbers the orbit is propagated from.
- Crew: The Space Devs (Launch Library 2), through a proxy of our own that also caches the answer for a few hours. We built it that way because several Spanish ISPs block that address, and visitors from Spain were seeing an empty panel.
- Imagery: NASA's official image and video library.
- News: the Spaceflight News API, which aggregates specialist outlets.
None of these organisations is affiliated with us or endorses us. We use their open data like any other user.
How the trajectory is computed, and how accurate it is
The position marked on the map is measured data. The line showing where the station is heading next is not: it is a calculation. It runs on the station's official orbital parameters, refreshed automatically, and it happens entirely in your browser, without passing through any server of ours.
It is worth knowing how much to trust that. An orbit propagated from a recent TLE is very good for the next few hours and degrades over days, because the ISS does not move through a perfect vacuum: drag from the upper atmosphere slows it down, and several times a year its engines fire to raise the orbit again or to dodge space debris. Any of those manoeuvres invalidates the previous prediction until fresh elements are published. That is why the visible passes we calculate are reliable for tonight and the next few days, and should be treated as guidance rather than as an ephemeris.
How the news section is made
The news section runs on an automated process, and we say so openly, because we think that is the right thing to do. A system reviews what space outlets publish several times a week, picks what actually concerns the station, and writes its own summary, cross-checking that information against the site's live data: the real altitude at that moment, who is aboard, the orbital context.
From that follow three rules we always keep:
- Every article links to the original outlet, and that link is always visible, not buried at the end.
- We do not reproduce other people's photographs. Each article's cover image is an illustration created for this site.
- If you spot an error, write to us and we will correct it or take the article down. An email is all it takes.
What ISS-Tracking is not
Worth stating plainly so nobody is caught out. We are not an official source and we do not replace one: for operational data, re-entry warnings or mission information, go to NASA, ESA or Roscosmos. We do not track other satellites. We do not sell the data and we offer no API. And we do not guarantee the site will be up at all times: it depends on third-party services that can fail or change without notice.
Questions or suggestions?
If something isn't working as it should, or you've thought of something that would make the site better, reach out via the Contact page.