NOAA 20 (JPSS-1)

NOAA 20, cataloged under NORAD ID 43013 and internationally designated 2017-073A, is an American Earth-observing satellite operated by the National Oceanic and Atmospheric Administration (NOAA). Launched on November 17, 2017, it serves as the first operational spacecraft of the Joint Polar Satellite System (JPSS), a next-generation program designed to sustain and improve the United States' polar-orbiting environmental satellite capability. Flying in a near-circular sun-synchronous orbit at roughly 831–832 km altitude, NOAA 20 continues to function as a cornerstone of global weather forecasting and environmental monitoring infrastructure.

Mission and Purpose

NOAA 20 was built to carry forward and strengthen a long tradition of American polar-orbiting weather satellites that stretches back decades. Its institutional predecessor program, the Polar Operational Environmental Satellites (POES), had provided continuous environmental data from low Earth orbit since the 1970s, and as those older platforms aged, the Joint Polar Satellite System was developed as their modern replacement. NOAA 20, known before launch as JPSS-1, became the first fully operational JPSS satellite to reach orbit.

The satellite's core purpose is the continuous collection of atmospheric and surface data across the entire globe. Orbiting from pole to pole, it sweeps across the Earth's surface in overlapping swaths, crossing the equator approximately 14 times each day. This geometry ensures that no region of the planet goes unobserved for long — complete global coverage is achieved twice every 24 hours. Such comprehensive data collection is essential for numerical weather prediction models, which depend on dense, worldwide observations to generate accurate forecasts.

Among the environmental variables that the satellite is designed to measure are atmospheric temperature profiles at various altitudes, moisture content throughout the troposphere and stratosphere, cloud properties and coverage, sea-surface temperatures, ocean color and biology indicators, sea ice extent, and signatures associated with volcanic ash plumes. The satellite also contributes to fire detection, allowing emergency managers and meteorologists to track wildfire spread and intensity. In the context of tropical cyclone forecasting, the data helps analysts assess storm structure, intensity, and likely track — information that feeds directly into warnings issued to the public.

NOAA 20 was designed to work in coordinated fashion with the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, which had entered service earlier. The two spacecraft share the same orbital plane but are phased roughly 50 minutes apart. This staggered arrangement increases the temporal resolution of global observations: rather than waiting a full orbit for a second look at a given region, forecasters receive updated data more frequently, improving the timeliness of warnings and model initialization.

Orbit and Tracking

NOAA 20 occupies a sun-synchronous orbit (SSO), a specialized class of low Earth orbit in which the satellite's orbital plane precesses at a rate that keeps it aligned with the Sun throughout the year. In practical terms, this means the satellite passes over any given location on Earth at approximately the same local solar time on every orbit, ensuring consistent lighting conditions for optical and infrared sensors. Sun-synchronous orbits are the standard configuration for environmental and remote-sensing satellites because the repeatability of illumination angles makes it far easier to detect genuine changes in surface conditions across successive passes.

Current tracking data places NOAA 20's apogee at 832 km and its perigee at 831 km, indicating an extremely circular orbit with almost no eccentricity. The orbital inclination is 98.8°, the slightly retrograde tilt that characterizes sun-synchronous trajectories in practice. With an orbital period of 101.4 minutes, the satellite completes just over 14 revolutions of the Earth each day, consistent with the pole-to-pole crossing frequency that enables its twice-daily global coverage.

The satellite's NORAD ID (43013) and COSPAR designator (2017-073A) are the authoritative identifiers used by tracking networks worldwide to distinguish NOAA 20 from the thousands of other objects cataloged in low Earth orbit. These identifiers link to the two-line element sets (TLEs) that are regularly updated by United States Space Force tracking assets and made available through public databases, allowing observers, mission operators, and researchers to compute current and predicted positions. As of the time of this writing, NOAA 20 remains in orbit with no scheduled or predicted reentry.

At an altitude of approximately 831–832 km, NOAA 20 resides well above the densest part of the upper atmosphere, where atmospheric drag is extremely low. This contributes to a high degree of orbital stability and helps explain the nearly perfect circularity of the orbit — minimal drag means minimal asymmetric decay. Long-term station-keeping maneuvers are nonetheless required to maintain the precise phasing with Suomi NPP and to correct for perturbations introduced by Earth's non-uniform gravitational field and solar radiation pressure.

Design and Operator

NOAA 20 was manufactured by Ball Aerospace & Technologies, a Colorado-based aerospace firm with an extensive history of building scientific and environmental spacecraft. The satellite has a launch mass of 2,540 kg, placing it in the category of medium-to-large Earth observation platforms. This mass budget accommodates the spacecraft bus, propulsion system, power generation hardware, and the suite of scientific instruments that represent the mission's functional core.

The satellite carries a set of advanced sensors inherited and improved from earlier polar-orbiting satellite generations. These instruments collect data across a wide range of the electromagnetic spectrum, from visible wavelengths through thermal infrared and into the microwave bands, enabling measurements of quantities that cannot be retrieved from a single spectral region alone. Microwave sounding instruments, for instance, can profile the atmosphere even through heavy cloud cover, while infrared sensors provide high-resolution temperature and moisture retrievals when skies are clear.

NOAA, as the operating agency, is responsible for satellite command and control, data downlink, processing, and distribution. NOAA's constellation management integrates data from NOAA 20 with observations from other sources — including geostationary satellites, weather balloons, aircraft, and ocean buoys — to produce the blended datasets that feed operational forecast models run by the National Weather Service and partner agencies internationally.

The Joint Polar Satellite System program itself is a collaboration involving NOAA, NASA, and the Department of Defense, with NASA playing a leading role in satellite acquisition and early on-orbit checkout before operational control is transferred to NOAA. This collaborative model has been standard for American operational environmental satellites for several decades.

Significance and Current Status

NOAA 20's arrival in orbit in late 2017 marked an important transition point for American operational meteorology. The JPSS program had faced programmatic delays and budget pressures in the years before launch, and there was genuine concern within the meteorological community about a potential gap in polar satellite coverage if older platforms failed before a replacement was available. The successful launch and commissioning of NOAA 20 therefore represented not just the addition of a new satellite but the restoration of redundancy and resilience in the nation's weather observing architecture.

The satellite's contributions to forecast accuracy are difficult to quantify in isolation, since modern numerical weather prediction is a deeply integrated system, but studies of data-denial experiments — in which researchers simulate the removal of specific observation types from model runs — consistently show that polar-orbiting satellite data, and JPSS-class data in particular, has among the largest positive impacts on forecast skill of any single observation source. This is especially true for forecasts beyond a day or two, where the initialization of large-scale atmospheric structure from global observations becomes the dominant factor in model accuracy.

NOAA 20 remains an active, functioning spacecraft. Its catalog entry does not record a decay or reentry date, reflecting the fact that it continues to operate from its sun-synchronous orbit. A second JPSS satellite, NOAA-21 (JPSS-2), has since been launched, expanding the constellation further and adding an additional layer of redundancy. Nonetheless, NOAA 20 remains an integral component of the operational system, contributing its observations alongside those of its constellation partners every day.

How to Spot It

NOAA 20 is occasionally visible to the naked eye from the ground under favorable conditions, though it is not among the brightest objects in the low-Earth-orbit population. At roughly 831–832 km altitude, it is higher than the International Space Station and consequently moves somewhat more slowly across the sky from an observer's perspective, taking several minutes to traverse from horizon to horizon on a good pass.

Because NOAA 20 is in a sun-synchronous orbit with an inclination of 98.8°, it passes over all latitudes up to just under the polar regions and is accessible to observers across a very wide geographic range, including most of North America, Europe, Asia, and the Southern Hemisphere mid-latitudes. The most favorable passes occur when the satellite is sunlit against a dark sky — in the hours shortly after evening twilight or before morning twilight. The satellite will appear as a steady, non-blinking point of light moving smoothly across the sky; unlike aircraft, it shows no navigation lights and maintains constant brightness except when it enters or exits Earth's shadow.

Precise pass predictions for any given location can be generated using the satellite's current TLE data, referenced by NORAD ID 43013, through any standard satellite tracking application or website.