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satellitedata.dev

A free catalog of objects in orbit: every satellite, rocket stage and piece of debris since Sputnik, the latest US Space Force orbital elements, and a log of every launch, with versioned URLs you can cite.

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What it is

satellitedata.dev republishes two public sources about objects in space as plain files and a simple API. The first is the US Space Force’s orbital data, which it publishes through Space-Track.org. The second is the General Catalog of Artificial Space Objects (GCAT), a catalog of every launch and every object kept by the astronomer Jonathan McDowell. You don’t need a key or an account.

It belongs to a family of data sites that share one design: one schema per dataset, versioned URLs, and a stated license and credit line for every source. Like this site, it’s run by Eric Ness. Treat it as you would any other secondary copy of someone else’s data: useful, but not the original.

What it measures

It has three datasets:

  • Current orbital elements (gp-current): the newest orbit for every object in Earth orbit that the Space Force publishes. Each row is one object, keyed by its US catalog number, with the standard SGP4 elements (mean motion, eccentricity, inclination and so on) and the time they apply to. The site adds period, semi-major axis, perigee and apogee, worked out from those elements; it labels the last three approximate.
  • Satellite catalog (satellite-catalog): one record for every artificial object GCAT lists since Sputnik in 1957, including payloads, rocket stages, debris, and objects that reentered, left for deep space or never reached orbit. Each has its owner, country, launch and decay dates, mass, status and latest orbit.
  • Launch log (launches): one row per launch in GCAT’s list since 1942, including failures, missiles and sounding rockets, with the vehicle, launch site, agency and outcome.

The catalog and launch log update daily. The orbital elements are listed as hourly, but the site checks Space-Track once a day, and in November 2026 its version history showed one new version a day.

The six-digit change. Every tracked object has a US catalog number. The old Two-Line Element (TLE) format, used for decades to share orbits, only has room for five digits. CelesTrak, a long-running orbital data site that works with Space-Track, reports that the five-digit numbers ran out on 11 July 2026. Objects cataloged since then are numbered 100000 and up, and their orbits can’t be written as TLEs. satellitedata.dev stores catalog numbers as plain integers, so its orbital elements include those newer objects.

The site also builds three yearly counts by country (new satellites owned, launch attempts, and launches from each country’s sites) and charts them on visualizedata.org.

What it misses

The public catalog isn’t everything in orbit. The Space Force also tracks objects it hasn’t tied to a launch, called “analyst objects.” McDowell notes that only a subset of these is released; Space-Track reported about 17,600 in February 2022, far more than the data released for them.

Orbital elements are a model, not a position. They are mean elements fitted from tracking data for the SGP4 orbit model, so you need SGP4 to turn them into a position at a given time. The perigee and apogee the site adds are approximate.

GCAT is one person’s careful work. McDowell resolves names, owners and dates that official records leave messy, and he marks guesses. Many dates are only known roughly (“1971?”). Masses are often estimates, good to about 20 percent by GCAT’s own flag, and most debris has none. The catalog number is missing for some objects, and some objects share their parent’s number.

Owner and country are GCAT codes, not ISO codes. “SU” is the Soviet Union, and intergovernmental bodies have their own codes. Counts by country use the current owner, not the owner at launch.

It’s a copy. For orbital work that matters, such as conjunctions, reentry or anything operational, go to Space-Track.org itself. For history, check GCAT’s own pages, which explain each code.

How to access it

1Browse the datasets

Start at satellitedata.dev/datasets/. Each dataset page has a preview, the full column list with units, the license and credit line, and every URL for that dataset.

2List what’s there

The catalog lists every dataset with its current version and date range:

curl -s "https://api.satellitedata.dev/v1/catalog"

When we tested it on 14 November 2026, it returned the three datasets. The launch log ran from 13 June 1942 to 12 November 2026, and the satellite catalog from 4 October 1957.

3Get rows for one group of objects

The orbital elements are split into files by catalog number, in blocks of 1,000. The International Space Station is number 25544, so it’s in block 25000:

curl -s "https://api.satellitedata.dev/v1/gp-current/table/25000.json"

This returned 365 objects, including ISS (ZARYA), international designator 1998-067A, with a period of about 92.9 minutes and a perigee of about 414 km. The satellite catalog is split by status instead (in-orbit, reentered, deep-space and others), and the launch log by kind of launch. /v1/{dataset}/locations lists the parts.

4Download a whole dataset

Each dataset comes as one CSV or Parquet file, for example https://api.satellitedata.dev/v1/satellite-catalog/download/satellite-catalog.csv. Parquet is smaller and keeps the column types. Without a key you can make 120 requests a minute, so download the whole file once instead of fetching thousands of small ones.

5Read the docs

The docs cover the URL scheme, formats, versions and errors. The API reference lists every endpoint for every dataset.

How to cite it

Every update gets a version id, such as 2026-11-07.239a7ef47b (the publish date and part of a hash of the files). Put it after the dataset id and the URL always returns the same data:

curl -s "https://api.satellitedata.dev/v1/gp-current@2026-11-07.239a7ef47b"

/v1/{dataset}/versions lists them. Most versions are removed after about 30 days, but the first version of each month is kept for good, and the docs say to cite those. Cite the agency or author that made the data, use the site’s exact credit line, and give the pinned URL. For example:

USSPACECOM, 18th Space Defense Squadron. Current orbital elements (gp-current), version 2026-11-07.239a7ef47b. Orbital data from Space-Track.org, provided by USSPACECOM (18th Space Defense Squadron). Via satellitedata.dev, https://api.satellitedata.dev/v1/gp-current@2026-11-07.239a7ef47b. Accessed 14 November 2026.

For the catalog and launch log, credit “data from GCAT (J. McDowell, planet4589.org/space/gcat)”. GCAT is licensed CC BY 4.0. The orbital data carries Space-Track’s redistribution terms, which the site says allow commercial use.

Sources & further reading

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