GeoXO (Geostationary Extended Observations)

Overview

GeoXO (Geostationary Extended Observations) is a planned constellation of three satellites developed by NOAA (National Oceanic and Atmospheric Administration) in collaboration with NASA. The mission is designed to advance environmental monitoring across the Western Hemisphere. It builds on the foundation of the GOES-R series, a fleet of four geostationary satellites that currently provide critical weather, climate, and solar activity monitoring. As the GOES-R series nears the end of its operational lifetime, GeoXO will serve as its replacement. The new mission aims to enhance current capabilities by improving visible and infrared imagery, advancing lightning mapping, and introducing innovative technologies such as hyperspectral sounding, atmospheric composition analysis, and ocean color observations. 5) 6) 7)

GeoXO will enhance extreme weather detection, enabling faster reaction times for both the public and emergency services, minimizing human and economic losses in vulnerable regions. GXI will improve wildfire detection, while LMX will expand the ability to monitor flash floods, improving coverage in areas that will benefit significantly. Economically, it will support industries such as agriculture and fisheries with precise weather forecasting, allowing for improved resource planning. For climate monitoring, ACX will track air pollution, while OCX will monitor water quality and marine health, aiding environmental and public health efforts. 7)

Spacecraft

GeoXO will consist of three geostationary satellites. Spacecraft in GEO-East and GEO-West positions will carry an imager, lightning mapper, and ocean color instrument, and a centrally-located spacecraft will carry a sounder and atmospheric composition instrument. Several commercial companies have been contracted to design and develop the components for the GeoXO satellite system. 5) 7)

In June 2024, NASA selected Lockheed Martin to build the GeoXO spacecrafts, with an initial contract for three spacecraft and an option for four additional ones. The design will build upon the LM 2100 bus, a scalable 3-axis stabilized satellite platform currently being used for the GOES-R series. The GeoXO satellite will offer improved performance and flexibility through upgrades like SmartSat, which enables the satellite to adapt to evolving mission needs, thereby extending its operational life. The specifications of the LM 2100 bus are shown in the table below. 1) 2)

Mission Status

• September 17, 2024: NASA, on behalf of NOAA, has selected Lockheed Martin to build LMX, with  a $297.1 million cost-plus-award-fee contract. Under this contract, Lockheed Martin will design and build the LMX instrument, which includes the development of two flight units, with options for two more.
• June 18, 2024: NASA, on behalf of NOAA, has awarded Lockheed Martin a $2.27 billion contract to design and build next-gen spacecraft. Under this contract, Lockheed Martin will develop three spacecrafts, with options for four additional units, to support future missions.
• May 20, 2024: NASA, on behalf of NOAA, selected BAE Systems to build OCX with a $450 million contract. Under this agreement, BAE Systems will design and develop the OCX instrument, including two flight units, with options for additional instruments.
• May 1, 2024: NASA, on behalf of NOAA, selected BAE Systems to build ACX with a $365 million contract. Under this agreement, BAE Systems will design and develop the ACX instrument, including one flight unit, with options for additional instruments.
• September 11, 2023: NASA, on behalf of NOAA, selected Ball Aerospace to build GXS with a $486.9 million contract. Under this agreement, Ball Aerospace will design and develop the GXS instrument, including one flight unit, with options for additional instruments.
• March 13, 2023: NASA, on behalf of NOAA, selected L3Harris to build GXI with a $765.5 million contract. Under this agreement, L3Harris will design and develop the GXI instrument, including two flight units, with options for additional instruments.

Sensor Complement

Atmospheric Composition Instrument (ACX)

ACX is a hyperspectral spectrometer located on the GEO-Central satellite, designed to observe a wide range of the spectrum from UV to visible light, with a spectral resolution of 0.6 nm. It will provide hourly observations of air pollutants such as ozone, nitrogen dioxide, and particulate matter, offering a temporal resolution of 1 hour. The ACX will have two instruments: one operating in the ultraviolet (300–500 nm) to detect fine absorption features from various trace gases like ozone, nitrogen dioxide, formaldehyde, and sulfur dioxide, as well as aerosol optical depth; and the second in the visible range (540–740 nm) to cover the oxygen-B absorption region for monitoring cloud and aerosol layer height, boundary layer ozone, and vegetation. The instrument will provide coverage over the United States, southern Canada, northern Mexico, and the Caribbean, with a spatial resolution of 8 x 3 km² at nadir, enabling the differentiation of various pollution sources. 8) 11)

Hyperspectral Sounder (GXS)

GXS will be NOAA’s first geostationary hyperspectral infrared instrument, positioned on the GEO-Central satellite. It marks a significant advancement as the first IR hyperspectral sounder to provide continuous coverage for the United States. GXS utilizes 1,550 spectral bands (far surpassing the 18 bands of ABI, the current sounder) to gather detailed atmospheric data, enabling continuous spectra to be observed. Unlike existing sounders on polar-orbiting satellites, which offer limited temporal coverage and longer data transmission times, GXS’s geostationary orbit will provide hourly updates with improved spatial resolution of 4 km (compared to the previous 14 km). 8)

Its spectral range includes longwave infrared (IR) bands, capturing key atmospheric variables such as vertical temperature, low-level moisture, ozone, ammonia, and isoprene. Additionally, its short-to-midwave IR bands support measurements of vertical moisture, temperature, nitrous oxide, and carbon monoxide. With a spectral resolution equivalent to 0.0052 μm for the longwave IR and 0.0012 μm for the short-to-midwave IR, GXS will achieve the vertical resolution necessary for detailed observations of moisture, temperature, and other critical atmospheric components, enhancing weather prediction and climate monitoring capabilities. Details of GXS’s specifications are displayed in Table 3. 8) 9)

Lightning Mapper (LMX)

LMX is a single-channel CMOS sensor operating at 777.4 nm, designed to detect, locate, and measure the intensity, duration, and extent of lightning flashes. Monitoring lightning is critical not only because it poses significant hazards to human activities but also because it serves as an indicator of other severe weather phenomena, such as heavy rainfall, strong winds and the start of wildfires. LMX will build upon the current Geostationary Lightning Mapper (GLM) by offering enhanced spatial and temporal resolution, a higher signal-to-noise ratio, and an expanded field of view. These improvements will enable the detection of fainter optical signals, increasing detection efficiency and reducing response times. Additionally, LMX will extend coverage to include a large fraction of the disk and northern regions such as Alaska, providing continuous monitoring over a broader area. While LMX remains in the initial design phase, the specifics of its advancements are still under development. 8) 10)

Visible/IR Imager (GXI)

GXI is a multi-channel passive radiometer that will deliver high-resolution visible and infrared imagery of the Western Hemisphere from the Geo-East and Geo-West satellites. Building upon NOAA's current Advanced Baseline Imager (ABI), which operates with 16 spectral bands. GXI will introduce two additional channels and enhance the resolution of seven existing channels by approximately a factor of four, enabling more precise observations. Notable advancements include improvements to the resolution of the visible and infrared bands, as well as the addition of channels designed to enhance low-level water vapor detection. GXI will scan the Full Disk every 10 minutes, the contiguous U.S. every 5 minutes, and smaller regions every 30 seconds to 1 minute, offering unprecedented temporal and spatial coverage. 8)

Ocean Colour Instrument (OCX)

OCX is a hyperspectral passive imaging radiometer that will monitor oceanographic features within the USA’s Exclusive Economic Zone (EEZ) and the Great Lakes. It will be stationed on the Geo-East and Geo-West satellites, addressing limitations in current ocean color observations, which are less frequent and therefore more susceptible to cloud coverage interference. By operating from a geostationary orbit, OCX will achieve a temporal resolution of three hours during daylight (two hours for the EEZ East and an additional hour for the Great Lakes), reducing the impact of cloud coverage. Both spatial and spectral resolution will be significantly improved compared to current low-Earth-orbiting sensors, with hyperspectral resolution featuring 10–20 nm band spacing and approximately 390 m spatial resolution at nadir. Operating in the 0.350–0.890 μm range, OCX achieves a signal-to-noise ratio (SNR) of ≥ 600:1, with potential for values up to 1,020:1 at 1.02 μm. This improved resolution, frequent imaging and high SNR ensures greater precision in detecting subtle oceanographic and atmospheric features, enhancing capabilities for monitoring water quality, harmful algal blooms, and other key marine phenomena. Details of OCX’s specifications are summarised in the table below. 8) 12)

Ground Segment

The GeoXO mission will rely on NOAA's Satellite Operations Facility (NSOF) in Suitland, Maryland, as the central hub for satellite command, control, and data processing. Ground stations across the United States, including those at Fairbanks, Alaska, and Wallops Island, Virginia, will provide critical support for telemetry, tracking, and command (TT&C), as well as data reception.

References  

1) "LM2100: Proven & Powerful", Lockheed Martin, 2024, URL: https://www.lockheedmartin.com/content/dam/lockheed-martin/space/documents/satellite/LM2100-Insert.pdf

2) "Now Installing Update… SmartSat-equipped Satellite Uploads New Mission While On-Orbit," Lockheed Martin, January 2024, URL:  https://www.lockheedmartin.com/en-us/news/features/2024/smartsat-equipped-satellite-uploads-new-mission-on-orbit.html

3) "Lockheed Martin Selected to Develop Next Generation Weather Satellite Constellation," Lockheed Martin, June 2024, URL: https://news.lockheedmartin.com/2024-06-18-Lockheed-Martin-Selected-to-Develop-Next-Generation-Weather-Satellite-Constellation

4) "Lockheed Martin Awarded GeoXO Lightning Mapper Contract to Support Forecasters with Severe Weather Monitoring. Lockheed Martin," Lockheed Martin, September 2024, URL:  https://news.lockheedmartin.com/2024-09-18-Lockheed-Martin-Awarded-GeoXO-Lightning-Mapper-Contract-to-Support-Forecasters-with-Severe-Weather-Monitoring

5) "GEOXO Mission Summary," CEOS MIM Database, URL: https://database.eohandbook.com/database/missionsummary.aspx?missionID=980

6) "Geostationary and Extended Orbits (GeoXO)," NOAA, March 2021, URL: https://www.nesdis.noaa.gov/sites/default/files/GEO-XO_FactSheet.pdf

7) "Geostationary Extended Observations (GeoXO)," NOAA/NESDIS, URL: https://www.nesdis.noaa.gov/next-generation/geostationary-extended-observations-geoxo

8) Lindsey, D. T., Heidinger, A. K., Sullivan, P. C., McCorkel, J., Schmit, T. J., Tomlinson, M., ... & Rudlosky, S. (2024). "GeoXO: NOAA’s Future Geostationary Satellite System," Bulletin of the American Meteorological Society, 105(3), E660-E679.

9) Schmit, T. J., Li, Z., Li, J., Gunshor, M., Tobin, D., & Heidinger, A. (2023, January), "Information Content from the GeoXO Sounder (GXS)," In 103rd AMS Annual Meeting. AMS.

10) Pratlong, J., Gil-Otero, R., Tsiolis, G., Kendall, J., Turner, P., & Bellett, G. (2023, October), "GeoXO Lightning Mapper (LMX) Engineering Demonstrator Unit Design and Silicon Results," In Sensors, Systems, and Next-Generation Satellites XXVII. SPIE. URL: https://doi.org/10.1117/12.2686283

11) Efremova, B., Bacon, E., Cook, M., Padula, F., McCorkel, J., Heidinger, A., & Joiner, J. (2023, December), "GeoXO Atmospheric Composition Instrument (ACX) Measurements Conditions Assessment," In 23rd Meeting of the American Geophysical Union (AGU). AGU.

12) Efremova, Boryana, et al. "GeoXO Ocean Color Instrument (OCX) Spatial and Temporal Coverage Assessment," 103rd American Meteorological Society (AMS) Annual Meeting. 2023.