The Complete Satellite Tracking Guide: How to Track Any Object in Orbit

What Is Satellite Tracking and Why It Matters

Satellite tracking is the process of determining and predicting the position and velocity of artificial objects orbiting Earth. It encompasses everything from locating the International Space Station for a backyard viewing opportunity to monitoring thousands of pieces of space debris that threaten operational spacecraft.

As of mid-2026, the US Space Force's 18th Space Defense Squadron tracks nearly 50,000 objects larger than 10 centimeters in orbit. Of these, more than 16,000 are active satellites, while the remainder consists of defunct spacecraft, spent rocket stages, and debris fragments. With mega-constellations like Starlink, OneWeb, and Amazon Kuiper deploying thousands of new satellites, the orbital environment is growing more congested than ever.

Satellite tracking matters for several critical reasons. Collision avoidance depends on accurate tracking data: a single collision can generate thousands of debris fragments, triggering a cascading chain of further collisions known as Kessler Syndrome. National security agencies track foreign military satellites and potential threats. Scientists use tracking data for atmospheric research, geodesy, and space weather studies. And the growing commercial space economy relies on tracking for spectrum coordination, insurance underwriting, and regulatory compliance.

Whether you are a hobbyist wanting to spot the ISS from your backyard, an engineer managing a satellite constellation, or a policy analyst studying orbital sustainability, understanding how satellite tracking works is foundational to engaging with the space domain.

How Satellite Tracking Works

Satellite tracking relies on a combination of ground-based sensors, space-based sensors, and mathematical models to observe, catalog, and predict the trajectories of orbiting objects. The process can be broken down into three key components: observation, cataloging, and propagation.

Observation: Detecting Objects in Orbit

The US Space Surveillance Network (SSN) operates a global network of radar and optical sensors to detect and track orbiting objects. Phased-array radars like the AN/FPS-85 in Florida can simultaneously track hundreds of objects, while the Space Fence on Kwajalein Atoll uses S-band radar to detect objects as small as 5 centimeters in LEO. Optical telescopes at sites like Diego Garcia and Maui observe objects in higher orbits where radar returns are too weak.

Commercial tracking providers are supplementing government networks. LeoLabs operates phased-array radars in Texas, New Zealand, Costa Rica, and Australia, providing near-real-time tracking of LEO objects. ExoAnalytic Solutions operates a network of over 300 telescopes worldwide for deep-space tracking. These commercial providers offer higher update rates and specialized analytics beyond what government catalogs provide.

Two-Line Element Sets (TLEs)

The standard data format for satellite orbital parameters is the Two-Line Element set (TLE), developed by NORAD in the 1960s. A TLE encodes six Keplerian orbital elements plus drag and timing information in two 69-character lines. The elements include inclination (the tilt of the orbit relative to the equator), eccentricity (how elliptical the orbit is), right ascension of the ascending node (the orientation of the orbital plane), argument of perigee (where in the orbit the satellite is closest to Earth), mean anomaly (where the satellite is in its orbit at the epoch time), and mean motion (how many orbits per day).

While TLEs remain the most widely used format, the space tracking community is transitioning to newer formats like Orbital Mean-Elements Message (OMM) in XML or JSON, and Orbit Ephemeris Message (OEM) for higher-precision applications.

SGP4 Propagation

Once a TLE is obtained, the Simplified General Perturbations 4 (SGP4) mathematical model is used to predict the satellite's position at any future or past time. SGP4 accounts for perturbations caused by Earth's oblateness (the J2 effect), atmospheric drag, solar and lunar gravitational effects, and solar radiation pressure. The model is specifically designed to work with TLE data and is implemented in virtually every satellite tracking application.

TLE accuracy degrades over time because the simplified model cannot perfectly capture all perturbations. For LEO objects, prediction accuracy is typically within 1-2 kilometers over a 24-hour period, but errors grow to tens of kilometers over a week. This is why TLEs are updated multiple times daily for high-interest objects.

Types of Orbits

Understanding orbit types is essential for satellite tracking because the orbit determines where and when a satellite is visible, how fast it moves across the sky, and what tracking methods are most effective. Here are the primary orbital regimes:

LEO is the most congested regime, hosting the majority of active satellites and trackable debris. Objects in LEO complete an orbit roughly every 90 minutes, making them visible from the ground for only a few minutes per pass. GEO satellites appear stationary from the ground, making them easy to point a dish antenna at but harder to distinguish from background stars with optical sensors. MEO and HEO orbits present unique tracking challenges due to their varying altitudes and speeds.

Explore orbital slot allocations and availability on SpaceNexus →

Key Tracking Data Sources

Reliable tracking data is the foundation of space situational awareness. Multiple organizations provide satellite tracking data, each with different coverage, accuracy, and access models:

SpaceNexus aggregates data from multiple sources to provide the most comprehensive tracking picture. Our satellite tracker ingests TLE data from Space-Track and CelesTrak, enriches it with metadata from our company intelligence database, and overlays conjunction assessment data to provide a complete operational picture.

How to Track the ISS and Other Notable Satellites

The International Space Station is the easiest satellite to track because of its size (about the area of a football field) and its low orbit (approximately 420 km altitude). It is often the third-brightest object in the night sky, after the Sun and Moon, reaching a visual magnitude of -5.9 at its brightest.

Step-by-Step: Track the ISS

1. 1Visit the SpaceNexus Satellite Tracker and search for "ISS" (NORAD ID 25544).
2. 2Enter your location to see upcoming visible passes with azimuth, elevation, and timing data.
3. 3Look for passes that reach at least 40 degrees elevation for the best viewing. The ISS appears as a bright, steady light moving across the sky in 3-5 minutes.
4. 4Best visibility occurs during twilight (just after sunset or before sunrise) when the sky is dark but the ISS is still illuminated by the Sun.

Other Notable Objects to Track

• ▸Tiangong Space Station — China's modular space station orbiting at ~390 km. Visible as a bright, steady moving object.
• ▸Hubble Space Telescope — Orbiting at ~540 km, visible as a moderately bright object (magnitude +1 to +2).
• ▸Starlink Trains — Newly deployed Starlink satellites form a visible "train" of lights before dispersing to operational altitude.
• ▸Envisat — The largest piece of space debris (8 tons), defunct since 2012, tracked closely due to collision risk.
• ▸GPS Constellation — 31 active satellites in MEO (~20,200 km). Too faint to see, but your phone uses signals from 4+ of them simultaneously for positioning.
• ▸GOES Weather Satellites — Geostationary satellites (GOES-18, GOES-19) that supply the imagery behind most weather forecasts. Fixed in the sky; telescope only.

Understanding Conjunction Assessments and Collision Avoidance

As the orbital environment becomes more congested, conjunction assessments have become a critical part of satellite operations. A conjunction occurs when two objects pass within a defined distance threshold. The 18th Space Defense Squadron at Vandenberg Space Force Base screens all trackable objects against each other and issues Conjunction Data Messages (CDMs) when the probability of collision exceeds a threshold.

A typical CDM includes the time of closest approach (TCA), the miss distance in radial, in-track, and cross-track directions, and the probability of collision (Pc). Satellite operators generally consider a collision avoidance maneuver when the Pc exceeds 1 in 10,000 (10^-4), though thresholds vary by operator and mission criticality.

SpaceX's Starlink constellation, with over 10,000 satellites, performs thousands of avoidance maneuvers per year using an autonomous collision avoidance system. In 2025, Starlink executed approximately 50,000 maneuvers, highlighting the scale of the traffic management challenge. Operators without maneuvering capability (such as small cubesats) must rely on ground-based conjunction screening and acceptance of residual risk.

The space industry is working toward more sophisticated Space Traffic Management (STM) frameworks. The Commerce Department has been designated as the civil authority for space traffic coordination in the United States, and international bodies like the Inter-Agency Space Debris Coordination Committee (IADC) are developing best practices for responsible space operations.

Monitor conjunction events and debris alerts on SpaceNexus →

Space Debris Tracking Challenges

Space debris represents one of the greatest challenges in satellite tracking. While the US Space Force tracks objects larger than 10 cm in LEO (roughly 48,000 objects), there are an estimated 130 million fragments between 1 mm and 10 cm that are too small to track reliably but large enough to damage or destroy a spacecraft. Even a 1-cm object at orbital velocity carries the kinetic energy of a hand grenade.

Major debris-generating events have dramatically worsened the environment. The 2007 Chinese ASAT test (destroying the Fengyun-1C satellite) created over 3,500 trackable fragments, many of which remain in orbit today. The 2009 Iridium-Cosmos collision added another 2,300 fragments. And the 2021 Russian ASAT test against Cosmos 1408 created 1,500+ fragments that threatened the ISS crew.

Tracking debris is harder than tracking active satellites because debris objects are often small, tumbling, and unpredictable. They do not transmit signals, so tracking relies entirely on ground-based sensors. Radar is effective for LEO debris, while optical telescopes are used for GEO debris. New technologies like space-based sensors and AI-enhanced tracking algorithms are improving detection capabilities for smaller objects.

Active Debris Removal (ADR) missions are beginning to address the problem. ClearSpace-1, a European Space Agency mission, aims to demonstrate debris capture and deorbiting. Astroscale has tested magnetic capture technology with its ELSA-d mission. These efforts, combined with improved tracking, are essential for ensuring the long-term sustainability of the orbital environment.

How to Use SpaceNexus Satellite Tracker

SpaceNexus provides a comprehensive satellite tracking platform that integrates data from multiple sources into a single, intuitive interface. Here is how to get the most out of it:

1. 1Search and filter — Find any satellite by name, NORAD ID, or COSPAR designator. Filter by orbit type, country, operator, or constellation.
2. 2Real-time visualization — View satellite positions on an interactive 3D globe or 2D ground track map with orbital paths projected forward in time.
3. 3Constellation view — Monitor entire constellations like Starlink, OneWeb, or GPS with our Constellation Tracker.
4. 4Conjunction alerts — Get notified when tracked objects have close approaches, with risk assessments and maneuver recommendations.
5. 5Debris monitoring — Track debris clouds from breakup events and their evolution over time via our Space Environment dashboard.

Frequently Asked Questions