INTELSAT 40E (IS-40E)

Intelsat 40e (IS-40e) is a geostationary communications satellite launched on April 6, 2023, and operated by Intelsat from a fixed position over the Western Hemisphere. Tracked under NORAD catalog ID 56174 and international designator 2023-052A, the satellite serves a dual commercial and scientific role: it functions as a high-capacity telecommunications relay while also hosting a landmark NASA and Smithsonian Institution environmental monitoring instrument. The combination of commercial communications infrastructure with a government-backed scientific payload makes IS-40e an unusually multifaceted addition to the geostationary arc.

Mission and Purpose

IS-40e was placed into service primarily to extend and strengthen Intelsat's coverage across North America and Central America, with particular emphasis on sectors that demand highly reliable, high-throughput connectivity. Commercial aviation, maritime and land-based mobility services, and broadband internet delivery are among the primary use cases the satellite was designed to support. Its position at 91° West longitude gives it a favorable line of sight across a broad swath of the North American continent and the Central American isthmus, making it well suited for aviation connectivity routes that crisscross the Gulf of Mexico and the Caribbean.

Beyond its commercial telecommunications function, IS-40e carries the Tropospheric Emissions: Monitoring of Pollution instrument, widely known by the acronym TEMPO. This payload was developed under the auspices of NASA and the Smithsonian Astrophysical Observatory and represents a significant advancement in atmospheric science. TEMPO is designed to monitor air quality across North America at a level of spatial and temporal resolution that had not previously been achievable from a geostationary orbit. By riding aboard a commercial host satellite, TEMPO benefits from continuous, stable positioning over its target region — something that low Earth orbit or sun-synchronous satellites can provide only in intermittent passes. The instrument tracks a range of pollutants and atmospheric constituents relevant to both regulatory oversight and climate research, including ozone, nitrogen dioxide, formaldehyde, and other tropospheric compounds. The ability to observe air quality over populated regions on an hourly or sub-hourly basis during daylight hours marks a qualitative step forward from earlier satellite-based monitoring methods.

This kind of hosted payload arrangement — in which a government agency places a scientific or operational instrument on a commercial satellite — has become an increasingly common and cost-effective approach. For Intelsat, accommodating the TEMPO instrument added scientific prestige and a government partnership to what is otherwise a commercial enterprise. For NASA and the Smithsonian, the arrangement allowed access to a geostationary vantage point without the expense of operating a dedicated government spacecraft.

Orbit and Tracking

IS-40e occupies a slot in the geostationary belt, the ring of orbital positions approximately 35,786 kilometers above Earth's equator where a satellite's orbital period naturally matches the planet's rotational period. Tracking data confirms the satellite is operating in a nearly circular orbit, with an apogee of 35,804 kilometers and a perigee of 35,786 kilometers — a difference of only 18 kilometers, which is consistent with the tightly controlled station-keeping typical of an operational geostationary satellite. Its orbital period is recorded at 1,436.1 minutes, essentially synchronous with one sidereal day, and its inclination is 0.0°, meaning the satellite remains fixed above the equatorial plane as seen from the ground.

From the perspective of a ground-based observer or a tracking system, IS-40e appears essentially stationary in the sky. It does not drift noticeably across its coverage area when viewed from a fixed point in North or Central America; instead, it holds its designated longitude with the small corrections that onboard propulsion systems routinely provide. This near-perfect geostationary configuration is what allows the satellite to maintain constant communication links with fixed dish antennas and airborne terminals without the need for tracking mechanisms that compensate for orbital motion.

The satellite was launched on April 6, 2023, and remains in orbit as of the most recent catalog update, carrying both its commercial communications and scientific payloads in active service. Its international designator, 2023-052A, identifies it as the primary payload of the 52nd tracked launch of 2023.

Design and Operator

IS-40e was designed and built by Maxar Technologies, a major American commercial satellite manufacturer. Maxar constructed the spacecraft on its SSL 1300 satellite bus, a platform with a long heritage in geostationary telecommunications. The SSL 1300, originally developed by Space Systems/Loral before that company was incorporated into the Maxar family, is one of the most widely flown commercial satellite bus designs in the industry and is noted for its flexibility in accommodating a wide range of payload configurations, power levels, and mission lifetimes. The platform has been used for numerous Intelsat satellites over the years, reflecting a well-established procurement relationship between the two organizations.

The satellite is operated by Intelsat, one of the world's largest commercial satellite operators by fleet size and orbital capacity. Intelsat has a decades-long history dating to the early years of commercial satellite communications and maintains an extensive network of geostationary satellites serving customers in telecommunications, broadcasting, government, and aviation sectors. IS-40e fits within the operator's broader fleet strategy of deploying high-throughput satellites to serve growing demand in mobility and broadband connectivity markets. The satellite is listed in orbital catalogs with Intelsat as both the operator and the owning organization.

The mass of the satellite is not publicly recorded in standard tracking catalogs, and the specific mission status and payload configuration details beyond those noted above are not confirmed in available data sources.

Scientific Significance: The TEMPO Instrument

The TEMPO instrument deserves particular attention given the significance it holds within the atmospheric and environmental sciences community. Prior to TEMPO's deployment, space-based air quality monitoring was largely dependent on polar-orbiting satellites that could observe any given location only once or twice per day. This infrequency made it difficult to track the diurnal evolution of pollution events — the way concentrations build during morning rush hours, peak during afternoon heat, and evolve through complex atmospheric chemistry across a day. TEMPO fundamentally changes this by providing observations from a fixed geostationary position, allowing researchers and environmental agencies to watch pollution dynamics unfold in near-real time across the entire North American continent.

The breadth of data that TEMPO generates has applications in public health research, air quality forecasting, regulatory enforcement, and climate modeling. Because it monitors the troposphere — the lowest layer of the atmosphere, where human activity and weather interact most directly — its measurements are directly relevant to ground-level conditions that affect human health and ecosystem function. The instrument's placement on a commercial satellite launched in April 2023 means that this scientific capability has been operational since the early part of that year, with data collection and analysis ongoing under the stewardship of NASA and the Smithsonian Astrophysical Observatory.

In a broader sense, TEMPO's deployment aboard IS-40e represents a proof of concept for the integration of high-value scientific instruments into commercial satellite missions. As the commercial satellite industry continues to grow and evolve, such arrangements may become more common, enabling scientific agencies to leverage the economics and launch cadence of commercial operators while contributing to a more comprehensive understanding of Earth's atmospheric systems.

Current Status

IS-40e remains in orbit and, based on its catalog classification and the operational context of the satellite, continues to fulfill its role as both a commercial communications relay and a scientific observation platform. The satellite holds its geostationary slot at 91° West longitude, maintaining the near-zero inclination and near-circular orbit documented in tracking data. No decay or reentry date has been recorded, which is consistent with the expected operational lifetime of a modern geostationary satellite, typically planned for service spanning a decade or more.

For users of this tracking site, IS-40e represents a type of geostationary object that will not arc across the sky in the manner of low Earth orbit satellites. Instead, for observers in North or Central America with a clear view toward the southwestern sky at the appropriate elevation angle, it occupies a fixed point in the geostationary arc. Its presence as a dual-use satellite — providing broadband and aviation connectivity while simultaneously recording hourly snapshots of the air quality over a continent — makes it one of the more scientifically notable commercial payloads currently occupying the geostationary belt.