CBERS 4

CBERS 4 (COSPAR designation 2014-079A, NORAD catalog ID 40336) is a civil remote sensing satellite operated as a cooperative venture between China and Brazil. Launched on 7 December 2014, it forms part of the long-running China–Brazil Earth Resources Satellite program, one of the most enduring examples of space cooperation between two major developing nations. The satellite remains in orbit as of this writing, continuing a legacy of Earth observation that stretches back more than two decades under the CBERS banner.

Mission and Purpose

The China–Brazil Earth Resources Satellite program was conceived in the 1980s as a framework for joint development, construction, and operation of Earth observation satellites, sharing both the technical burden and the data products between the two participating nations. China's lead agency in the program is the China National Space Administration, while Brazil's primary partner institution is the National Institute for Space Research (INPE). Through successive generations of satellites, the program has aimed to provide both countries — and, by deliberate policy, the broader developing world — with freely accessible imagery for land-use mapping, agricultural monitoring, deforestation tracking, disaster assessment, water resource management, and urban planning.

CBERS 4 slots in as the fifth spacecraft in the series to reach orbit. Its immediate predecessor, CBERS-3, was destroyed in a launch failure in December 2013, leaving a significant gap in the program's observational continuity. The development and launch of CBERS 4 was therefore treated with considerable urgency, and it lifted off in December 2014 — roughly one year after the loss — to restore that capability. The satellite carries a suite of optical and infrared imaging instruments designed to acquire multispectral imagery at a range of spatial resolutions, serving the overlapping scientific and governmental needs of both partner nations. The specific instrument complement and the precise imaging resolutions of CBERS 4 are well documented in program literature from INPE and CCAST, though the catalog entry tracked here does not independently record those mission-specific parameters.

Data from the CBERS series has historically been distributed at no charge, a policy that greatly expanded the user base in Africa, Asia, and Latin America — regions that might otherwise lack the resources to purchase commercial imagery. This open-data philosophy predates and arguably helped inspire similar policies later adopted by programs such as Landsat and Copernicus, lending the CBERS program an outsized influence on the norms of civil Earth observation.

Orbit and Tracking

CBERS 4 operates in a sun-synchronous orbit (SSO), a specialized near-polar orbital regime that is the standard choice for Earth observation missions requiring consistent, repeatable lighting conditions. In a sun-synchronous orbit, the satellite's orbital plane precesses at a rate that keeps it aligned with the terminator — the boundary between the sunlit and shadowed portions of Earth — so that the satellite crosses any given latitude at approximately the same local solar time on every pass. This consistency is essential for comparing imagery acquired weeks or months apart, because illumination angle and shadow geometry remain nearly identical, making change detection far more reliable.

The tracked orbital parameters for CBERS 4 place its apogee at 779 km and its perigee at 776 km, indicating an orbit that is very nearly circular, with an eccentricity approaching zero. This tight altitude band is typical of operational Earth observation platforms, which benefit from the geometric and radiometric stability that a circular orbit provides. The orbital inclination is 98.4°, slightly retrograde relative to the equator, which is the characteristic geometry of sun-synchronous trajectories — an inclination just past 90° allows the gravitational oblateness of Earth to drive the required nodal precession.

The orbital period is 100.3 minutes, meaning CBERS 4 completes roughly 14 to 15 full revolutions around Earth every day. Over successive days, the ground track shifts westward in a systematic repeating pattern, allowing the satellite's sensors to achieve periodic revisit coverage of any given point on the surface. At a nominal altitude of roughly 777 km, the satellite is well above the uppermost fringes of the atmosphere and experiences minimal aerodynamic drag, which contributes to the orbit's long-term stability — consistent with the fact that the satellite remains in orbit more than a decade after launch with no reentry recorded in the catalog.

Observers tracking CBERS 4 by its NORAD ID 40336 can obtain current two-line element sets from space surveillance sources to compute precise pass predictions. Like most sun-synchronous satellites at this altitude, it travels from high northern latitudes to high southern latitudes (and back) on a steeply inclined path, and its ground track is visible from most populated regions of Earth at some point during each day.

Design and Operators

CBERS 4 is formally classified as a payload — an active, functional spacecraft rather than a rocket body or debris object. It is jointly owned by China and Brazil, reflecting the equal-partnership character of the CBERS program under which both nations contribute to development costs and share the resulting data. The operating authority on the Chinese side rests with the China National Space Administration (CNSA), one of China's primary civilian space policy and program management bodies, while INPE handles operational coordination and data distribution on the Brazilian side.

The satellite is also known by the Chinese designation Ziyuan I-04 (or Ziyuan 1E), the "Ziyuan" series name meaning roughly "Earth Resources" in Mandarin, which is the domestic Chinese label for what the international community calls the CBERS satellites. The dual naming convention reflects the administrative reality that the program has distinct but parallel identities within the two partner countries' space bureaucracies.

The manufacturer of the satellite is not identified in the public catalog record maintained for this object. Construction of earlier CBERS spacecraft involved the Chinese Academy of Space Technology (CAST) and Brazilian engineering contributions coordinated through INPE, with the division of labor evolving across the series. The mass of CBERS 4 is similarly not recorded in the catalog entry tracked by LowEarth, so no specific figure is stated here.

CBERS 4 was launched on 7 December 2014, lifted to orbit by a Chinese Long March launch vehicle from a Chinese launch facility, with the launch occurring at 19:00 Eastern Standard Time on 6 December as recorded in the UTC-offset launch timestamp — corresponding to local and UTC times placing the event in the early hours of 7 December 2014. This was a fully successful launch, in deliberate contrast to the failure that had claimed CBERS-3 one year earlier.

Current Status and Significance

CBERS 4 is listed as still in orbit, and the near-circular, stable orbit it occupies at approximately 777 km altitude is not subject to rapid orbital decay. Satellites in well-maintained sun-synchronous orbits at this altitude have operational lifespans typically measured in years to decades before atmospheric drag or propellant depletion becomes a limiting factor. Whether the satellite's onboard systems remain fully functional is not confirmed in the catalog record tracked here, but its continued orbital presence means it remains a catalogued and trackable object.

The broader significance of CBERS 4 lies partly in what it represents programmatically. South–South space cooperation — partnerships between non-Western, non-Russian spacefaring nations — was relatively rare in the early decades of the space age, and the CBERS program demonstrated that such collaboration could produce a sustained, multi-generation series of operational spacecraft rather than a one-off demonstration. The program also established the principle that satellite remote sensing data could be made broadly available to developing nations as a matter of policy, a contribution that has had lasting effects on how Earth observation data is governed globally.

For Brazil specifically, the CBERS series provided access to domestic Earth observation capability that would otherwise have required either substantial investment in an independent national program or dependence on foreign commercial or governmental data suppliers. For China, it offered early experience in international space program management and an opportunity to demonstrate the maturity of its satellite manufacturing and launch capabilities to international partners.

How to Spot It

CBERS 4 orbits at approximately 777 km altitude in a sun-synchronous trajectory inclined at 98.4° to the equator, meaning its ground track reaches latitudes well into the northern and southern polar regions. From most locations in Europe, the Americas, Africa, Asia, and Australia, the satellite passes overhead multiple times each day, making it geometrically observable from a wide range of sites.

As a medium-sized Earth observation satellite in low Earth orbit, CBERS 4 is potentially visible to the naked eye under favorable conditions — specifically, when the observer is in twilight or darkness while the satellite itself is still illuminated by the sun, which occurs during the hour or two after sunset and before sunrise. Under these conditions, it would appear as a steadily moving point of light crossing the sky over the course of two to five minutes per pass, with no blinking (which would indicate an aircraft) and no color variation.

To obtain accurate pass predictions, use the NORAD ID 40336 or the COSPAR identifier 2014-079A with any satellite tracking tool that accepts current TLE data. Pass times, maximum elevation, and direction of travel are all calculable from current orbital elements and will vary by observer location and date.