Biggest Satellite in Orbit: The Heaviest Objects Ranked

The International Space Station (ISS) is the biggest satellite in orbit by mass, weighing roughly 420 tonnes. Its mass changes as visiting spacecraft arrive and depart, but the assembled station remains the heaviest human-made object orbiting Earth.

That answer needs a distinction: an assembled space station and an individual catalogue entry are different units of comparison. Tianhe leads Orbital Radar's individual-object mass ranking at about 22,500 kg as of 10 November 2026, according to Orbital Radar tracking data. Tianhe is the core module of China's three-module Tiangong station, not the entire orbital complex.

USA 290 has a catalogue mass of about 20,000 kg as of 10 November 2026, according to Orbital Radar tracking data. This article ranks objects by mass, rather than physical dimensions or apparent brightness, covering working stations, heavy spacecraft and discarded rocket stages. Orbital Radar's satellite library lets readers explore the objects behind those comparisons, while keeping complete stations distinct from their separately catalogued components.

Why is the ISS the biggest satellite in orbit?

The International Space Station (ISS) is the biggest artificial satellite in orbit by mass, with a commonly quoted mass of roughly 420 tonnes. An artificial satellite is any human-made object orbiting Earth: a crewed station qualifies just as a communications spacecraft does.

The ISS is an assembled complex, not a spacecraft launched in one piece. Its pressurised modules provide living and working space, structural trusses form its supporting framework, and solar arrays generate electricity. Visiting spacecraft add to the attached complex while they are docked.

That makes 420 tonnes an approximate, configuration-dependent reference rather than a fixed measurement. Docking and departures, supplies, propellant and equipment change the station’s total mass. Mass also differs from physical span: widely extended solar arrays can make a structure larger without adding proportionately to its weight.

The ranking later in this article compares individual catalogue mass entries, not assembled station totals. Tianhe has an approximate catalogue mass of 22,500 kg as of 10 November 2026, according to Orbital Radar tracking data. USA 290 has an approximate catalogue mass of 20,000 kg on the same date, according to Orbital Radar tracking data. Neither entry represents the complete ISS, so its absence does not displace it as the heaviest satellite. Orbital Radar’s ISS profile covers the assembled station.

How does Tiangong compare with the ISS?

Tiangong is smaller than the International Space Station (ISS), but it is a complete crewed station, not simply a single heavy satellite. China's entirely Chinese-built and operated outpost has three modules arranged in a T shape and orbits Earth at around 390 km. It is the only crewed station in orbit besides the ISS.

Tianhe has an estimated catalogue mass of 22,500 kg as of 10 November 2026, according to Orbital Radar tracking data. That figure describes Tianhe, the station's core module, rather than the complete Tiangong complex. Treating it as the whole station's mass would leave out the other modules and any spacecraft attached to them.

Tiangong has been permanently occupied by rotating three-person Shenzhou crews since 2022. Crew rotations bring arriving and departing spacecraft, while cargo deliveries also alter what is attached to the station. Its configuration and total mass therefore change over time, even though its basic three-module structure remains the same.

The distinction matters when comparing the biggest satellites in orbit: an individual catalogue entry and an assembled orbital complex are different things. Tianhe's listed mass should not be compared with the entire ISS as though both figures described equivalent structures. Orbital Radar's Tiangong glossary page explains the station's layout and role, helping put its core-module entry in the context of the larger inhabited outpost.

Which individual objects have the highest catalogue masses?

Tianhe leads these individual catalogue entries at about 22,500 kg, followed by USA 290, USA 338 and USA 314 at about 20,000 kg each. Orbital Radar tracking data lists Tianhe’s estimated individual-object mass as about 22,500 kg as of 10 November 2026.

The table is ordered by estimated individual-object catalogue mass, not by the total mass of assembled stations. A catalogue entry identifies a separately recorded object; it should not automatically be read as the mass of an entire connected spacecraft complex.

Estimated individual-object catalogue masses — descending estimates, not a definitive ranking of assembled stationsObjectEstimated massTianheAbout 22,500 kgUSA 290About 20,000 kgUSA 338About 20,000 kgUSA 314About 20,000 kgLijian-2 Stage 2About 17,000 kgUSA 53About 16,900 kgUSA 224About 14,000 kgUSA 186About 14,000 kgUSA 245About 14,000 kgYaogan 41About 12,000 kg

Every mass here is approximate. Equal rounded estimates do not establish a precise order: the listed sequence within the about-20,000 kg and about-14,000 kg groups does not demonstrate which object is actually heavier.

Catalogue names and mass estimates alone do not establish whether an object is operating, what instruments it carries or what missions it can perform. Orbital Radar’s satellite library provides a place to explore individual entries, but these mass estimates should be read as a comparison of recorded objects, not as evidence of their capabilities.

Why do launch mass and mass in orbit differ?

Launch mass is a spacecraft’s mass at launch, including its carried propellant; current orbital mass is an estimate of what remains in orbit in the configuration being compared. Burning propellant or releasing hardware reduces that mass, while arriving cargo and docked spacecraft can increase a station’s total.

Transfers also change the accounting boundary: moving cargo from a docked freighter into a station changes each component’s mass, but not the combined total. A comparison must therefore specify whether it covers an individual module, a free-flying spacecraft or an entire docked assembly.

Tianhe has an approximate catalogue mass of 22,500 kg as of 10 November 2026, according to Orbital Radar’s live catalogue. That entry describes the core module, not the whole Tiangong Space Station. Tiangong is a three-module station that has been permanently crewed since 2022; its assembled mass must not be replaced by Tianhe’s module-level figure.

Rounded masses in Orbital Radar’s satellite library are useful comparison points, not continuous readings from weighing instruments aboard each object. Unless explicitly identified as current estimates, they should not be treated as precise present-day masses.

Mass, physical size and brightness are different properties. Broad, lightweight solar arrays can make a spacecraft large without making it especially heavy; reflected sunlight depends on surface materials, orientation and viewing geometry, so brightness is not a reliable substitute for either size or mass.

How much of Earth's orbital mass is in heavy objects?

The estimated mass of objects in Earth orbit is 17,500 tonnes as of 10 November 2026, according to Orbital Radar tracking data. The International Space Station (ISS), Tianhe and other heavyweight objects contribute to that total, but their approximate masses do not support a precise percentage share.

The ISS is an assembled station, whereas Tianhe’s catalogue mass of about 22,500 kg describes a module of China’s Tiangong station, not the whole outpost. Other heavy entries in Orbital Radar’s satellite library include USA 290, USA 338 and USA 314 at about 20,000 kg each; comparing these entries requires keeping their different scopes in view.

Orbital Radar tracking data lists 16,685 active satellites within a broader inventory of 32,116 catalogued objects, which also includes inactive spacecraft, rocket bodies and debris. Active satellites are therefore only part of the population contributing to orbital mass, and an object’s inclusion in the catalogue does not mean it is operating.

Starlink accounts for 9,891 active satellites in Orbital Radar tracking data, illustrating why a constellation’s object count is a different measure from the mass of an individual spacecraft. Thousands of satellites distributed across a constellation should not be treated as a single contender for the heaviest object; readers interested in population rather than heavyweight rankings can use Orbital Radar’s satellite count page.

Why are spent rocket stages among the heaviest objects?

Spent rocket stages rank among the heaviest objects in orbit because their large tanks, engines and supporting structures remain after their propulsion work is finished. A rocket stage is a propulsion section discarded after completing its task; an upper stage can reach orbit alongside its payload and remain there after releasing it unless a subsequent manoeuvre sends it towards re-entry.

Orbital Radar's live catalogue lists Lijian-2 Stage 2 at about 17,000 kg, making it the rocket-stage entry in this heavyweight selection. That mass represents a substantial piece of launch hardware, rather than a satellite built to provide an ongoing service.

Orbital Radar tracking data lists 2,211 rocket bodies in Earth's orbital debris environment as of 10 November 2026. A rocket body is a separate catalogue category from a payload or a debris fragment: it identifies launch hardware, not its operational status. Being tracked means its orbit is being followed, not that it remains operational; these categories can be explored through Orbital Radar's Debris Map.

Retained propellant and stored energy matter because they can cause a discarded stage to rupture, producing fragments. Passivation (removing residual energy by venting propellant and discharging batteries) reduces that risk. This is a general concern for spent stages, not evidence that Lijian-2 Stage 2 retains propellant or has an unverified hazardous condition.

Are the heaviest dead satellites the most dangerous debris?

No: the heaviest defunct satellites are not automatically the most dangerous debris. Mass matters for collision consequences, but encounter speed, orbit geometry and the likelihood of a close approach also determine risk.

A defunct satellite is a spacecraft that no longer operates; an active spacecraft still performs a mission, while a spent rocket body is a launch stage left in orbit after its job ends. Catalogue mass alone does not establish operational status: the USA-designated entries and Yaogan 41 should not be labelled dead without evidence. Lijian-2 Stage 2, listed at about 17,000 kg, belongs to the rocket-body category rather than the satellite category.

Orbital Radar tracking data records 21 active close approaches being tracked as of 10 November 2026. A close approach is not a predicted collision: it identifies an encounter requiring assessment, not a certainty that objects will strike each other.

Orbital Radar tracking data places 3,677 objects in the 800–900 km average-altitude band, including 2,777 debris objects. The 500–600 km band contains 2,336 objects, including 33 debris objects. These contrasting surroundings illustrate why location matters alongside mass, although band totals alone cannot establish the risk to any particular spacecraft.

Orbital Radar's debris map lets readers explore that surrounding orbital environment. It provides context for a heavy object's neighbourhood, not a verdict that the object is safe or dangerous; that requires encounter-specific assessment, including orbital paths and uncertainties in the tracking.

Does a heavier satellite stay in orbit longer?

No: a heavier satellite does not necessarily stay in orbit longer. Orbital lifetime depends on altitude, atmospheric drag, shape, exposed area and mass together, rather than mass alone.

Atmospheric drag is resistance from the thin residual atmosphere through which a satellite moves. It removes orbital energy, gradually lowering the orbit. For otherwise comparable objects, a large exposed area relative to mass produces greater slowing: there is more surface catching the atmosphere for each kilogram being slowed. Shape and orientation also affect that resistance, while atmospheric density changes with altitude and solar activity.

Vanguard I, launched on 17 March 1958, remains catalogued in an orbit of about 657–3,935 km, according to Orbital Radar tracking data. This small satellite demonstrates that an enduring orbital object need not be a heavyweight. Its elongated orbit carries it between those lowest and highest altitudes, unlike a station operating much closer to Earth.

Tiangong operates at roughly 390 km as of 10 November 2026, according to Orbital Radar tracking data. Spacecraft manoeuvres can replace energy lost to drag and maintain an operating orbit; an uncontrolled object's evolution instead depends on its orbit and environmental forces. Orbital Radar's satellite library provides context for comparing these objects, but neither mass nor an altitude snapshot alone establishes a re-entry date.

How can you check the biggest satellites live?

Open Orbital Radar’s ISS tracker to check the International Space Station’s tracked position and orbital path, then open the Tiangong tracker alongside it. NORAD 25544 is the ISS catalogue identifier: it identifies the tracked object, not its place in a mass ranking.

Tiangong, permanently crewed since 2022, orbits at around 390 km, according to Orbital Radar tracking data. Comparing the tracking views shows where the stations are relative to Earth and how their orbital paths differ; it does not measure their masses.

Use Orbital Radar’s satellite library at /library to explore individual catalogue records, keeping each object’s identity separate from the total mass of a connected station. Tianhe has an estimated catalogue mass of about 22,500 kg as of 10 November 2026, according to Orbital Radar’s live catalogue. That entry describes Tiangong’s core module, not the combined mass of the assembled station and any docked spacecraft.

For naked-eye observing, consult Orbital Radar’s ISS viewing guide at /how-to-see-iss-tonight. Local visibility depends on illumination and viewing geometry: the station must be sunlit, above your horizon and sufficiently bright against the sky, rather than simply massive.

The practical rule is to compare like-for-like mass estimates, use tracking views for orbital position, and never interpret an estimated catalogue mass as a live measurement.

Key takeaways

• The ISS is the heaviest satellite in orbit, but its assembled mass should not be compared directly with a single module's catalogue entry.
• Tianhe leads this individual-object catalogue selection at about 22,500 kg, not as a measurement of the entire Tiangong station.
• Heavy orbital objects include discarded hardware, with Lijian-2 Stage 2 listed at about 17,000 kg.
• Mass alone does not determine collision risk, orbital lifetime or visibility from the ground.