NOAA 21 (JPSS-2)

NOAA 21, also catalogued under NORAD ID 54234 and international designator 2022-150A, is an American Earth-observing satellite operated by the National Oceanic and Atmospheric Administration (NOAA). Launched on November 9, 2022, it is the second spacecraft to fly as part of the Joint Polar Satellite System (JPSS), a collaborative program between NOAA and NASA designed to ensure the continuity of polar-orbiting environmental data for the United States. Prior to reaching orbit, the satellite was referred to as JPSS-2. With a mass of 2,540 kg, it ranks among the more substantial Earth-observing platforms currently in low Earth orbit, and its near-circular sun-synchronous trajectory keeps it in continuous productive use for global weather monitoring and environmental science.

Mission and Purpose

The Joint Polar Satellite System was conceived to replace and extend the capabilities of earlier generations of U.S. polar-orbiting weather satellites, ensuring that forecasters, climate researchers, and emergency managers have access to reliable, global atmospheric and surface observations. NOAA 21 slots into that framework as the second operational JPSS satellite, following its predecessor NOAA-20, and joining a constellation that also includes Suomi NPP, an earlier research-to-operations bridge satellite. Together, these spacecraft provide overlapping coverage that dramatically reduces the time between successive observations of any given area of the planet.

Polar-orbiting weather satellites occupy a fundamentally different niche than the geostationary platforms — such as NOAA's GOES series — that hold a fixed position above the equator. Because a polar orbiter sweeps across every latitude on Earth as the planet rotates beneath it, it builds up a complete picture of the entire globe over the course of roughly two orbital cycles per day. This geometry allows instruments to observe the poles and high-latitude regions that geostationary satellites can see only at extreme, distorted angles, making polar orbiters indispensable for Arctic and Antarctic monitoring, ocean surface temperature mapping, atmospheric sounding, and the detection of phenomena such as volcanic ash plumes and severe storm systems before they fully develop.

NOAA 21's suite of instruments — inherited in design from the JPSS program's established payload architecture — is intended to collect high-resolution data on atmospheric temperature and humidity profiles, cloud properties, sea surface temperatures, land surface conditions, vegetation health, snow and ice cover, and the intensity and distribution of solar and terrestrial radiation. These observations feed directly into numerical weather prediction models run by NOAA's National Weather Service and by partner agencies around the world. Improvements in forecast accuracy over recent decades are substantially attributable to the kind of global, vertically-resolved atmospheric data that JPSS-class satellites provide. The specific operational status and any post-launch mission milestones of NOAA 21 are not detailed in the current satellite catalog record.

Orbit and Tracking

NOAA 21 operates in a sun-synchronous orbit (SSO), a particular class of near-polar trajectory in which the orbital plane precesses at a rate that keeps it at a nearly constant angle relative to the Sun throughout the year. This means the satellite crosses any given latitude at approximately the same local solar time on every pass — a property of enormous practical value for Earth observation, because it ensures that successive images of the same location are acquired under consistent lighting conditions, making it far easier to compare data collected days, weeks, or months apart.

The satellite's orbital parameters reflect the precision typical of an operational Earth-observation mission. With an apogee of 832 km and a perigee of 831 km, the orbit is very nearly circular — the difference of just one kilometer between the highest and lowest points indicates an eccentricity close to zero. This consistency means that the satellite's altitude and ground-track geometry remain stable over time, simplifying data calibration and mission planning. The orbital inclination of 98.7° is slightly retrograde with respect to Earth's rotation, which is the standard configuration for sun-synchronous orbits at this altitude. The spacecraft completes one full revolution around Earth every 101.4 minutes, translating to roughly 14 orbits per day and enabling global coverage twice every 24 hours as successive ground tracks shift westward with each pass.

For satellite trackers and software systems, NOAA 21 is identified by NORAD catalog number 54234. Its two-line element sets, regularly updated from radar tracking data, allow precise predictions of its position and timing at any location on Earth. Because its orbital altitude places it well into the low Earth orbit regime, the satellite moves rapidly across the sky — a full pass from horizon to horizon typically takes only a few minutes as seen from the ground.

Design and Operator

NOAA 21 was manufactured by Northrop Grumman Innovation Systems, which was responsible for the spacecraft bus and overall satellite integration. The JPSS program as a whole involves close collaboration between NOAA, which operates the satellites and takes ownership of their data products, and NASA, which manages the acquisition and development phases. This partnership model has been a feature of U.S. operational meteorological satellites for decades, allowing NOAA to focus on data users and services while NASA brings its engineering and procurement expertise to bear during the build phase.

The satellite's mass of 2,540 kg places it in a category of substantial, multi-instrument Earth-observing platforms. Spacecraft of this size require considerable structural and power resources to accommodate the various instruments and support systems aboard, including attitude control, communications, and thermal management hardware. The JPSS bus was designed for longevity and reliability in a demanding radiation environment, with the expectation of extended operational service.

NOAA itself is the primary civil agency in the United States responsible for monitoring the atmosphere and oceans. Its satellite operations are managed through the NOAA Satellite and Information Service (NESDIS), which oversees a fleet of geostationary and polar-orbiting platforms. The data collected by NOAA 21 is freely distributed to domestic and international partners under long-standing agreements that recognize the global public good served by operational weather and environmental observations.

Program Context and Significance

The JPSS program represents the United States' long-term commitment to maintaining unbroken coverage of the globe from polar orbit, a capability that has been in place continuously since the earliest TIROS satellites of the 1960s. Any gap in this coverage would have serious downstream consequences for weather forecasting skill, particularly for medium-range forecasts — those extending five to seven days ahead — where polar-orbiter data has been shown to be among the most impactful observational inputs. NOAA 21's arrival in orbit ensured that the constellation had sufficient redundancy to guard against the loss of any single satellite.

The launch took place on November 9, 2022, and NOAA 21 joined an orbit already occupied by NOAA-20 and Suomi NPP, phased to maximize temporal coverage of any point on Earth. Operating multiple spacecraft in the same orbital shell — rather than at different altitudes — allows the agencies to minimize revisit times, so that the interval between successive observations of a storm or other developing feature is reduced. This architecture also facilitates continuity: as older satellites age and are eventually retired, newer ones can step in without gaps in the data record that scientists rely upon for climate research.

NOAA 21 also launched alongside LOFTID, a NASA technology demonstration project testing an inflatable aerodynamic decelerator intended for future planetary entry systems. While LOFTID was entirely separate from NOAA 21's meteorological mission, their shared rideshare launch underscores the common practice of secondary payloads accompanying primary government missions to increase the return on each launch.

As of the current catalog record, NOAA 21 remains in orbit and has not been assigned a decay or reentry date, consistent with an active operational spacecraft at its altitude.

How to Spot It

At roughly 831–832 km altitude, NOAA 21 orbits well above most of the atmospheric drag that causes rapid orbital decay, but it is still close enough to Earth to be visible to the naked eye under favorable conditions. The satellite does not carry any specialized reflective surfaces designed to enhance its brightness, but its size — a spacecraft massing 2,540 kg with deployed solar panels — gives it a meaningful cross-section that reflects sunlight effectively during twilight passes.

The best opportunities to observe NOAA 21 come during the hour or so after local sunset or before local sunrise, when the observer on the ground is in darkness but the satellite is still in direct sunlight at its orbital altitude. During such passes, NOAA 21 appears as a steadily moving point of light crossing the sky over several minutes, typically from horizon to horizon in around four to five minutes at most elevations. It does not flash or blink like a tumbling rocket body; its motion is smooth and consistent.

To find precise pass times and sky directions for your location, use the tracking tools on this site with NORAD ID 54234. Passes that reach higher elevations above the horizon will be brighter and easier to see; low-horizon passes may be dimmed by atmospheric extinction. No optical aid is needed for well-placed, high-elevation passes during twilight windows.