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Space systems and satellite services

Space systems and satellite services provide positioning, timing, communication and observation from orbit. Many terrestrial systems depend on them, making their disruption a cross-sector risk. Space and Earth Observation stewards this page for the Nexus Consortium.

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01Contents

Space systems and satellite services in six parts.

In this dossier6 parts
  1. 01The methodWhat space systems and satellite services covers
  2. 02Reference practiceSpace operations follow UN guidelines and coordination bodies
  3. 03In systemic risk workSatellites as critical infrastructure
  4. 04Applied inPlatforms that apply this method
  5. 05StewardshipWho maintains this page
  6. 06SourcesWhere this page’s references lead
02The method

What space systems and satellite services covers.

  1. 01

    Core methods

    orbit determination; space situational awareness; link budget analysis; space weather impact assessment; mission reliability analysis; ground segment design.

  2. 02

    Data and instruments

    satellite telemetry; space object catalogues; space weather monitors; ground station records; timing and positioning signal monitors.

  3. 03

    Validation

    Systems are tested on the ground before launch and monitored in orbit. Conjunction assessments and service performance are checked against independent tracking.

  4. 04

    Limits

    Debris growth, solar storms and interference are hard to forecast precisely. Ground segments and launch capacity are concentrated.

  5. 05

    Use in risk decisions

    Space systems analysis reveals dependencies of finance, power grids and transport on satellite timing and navigation. It supports planning for backups and space weather events.

03Geography

Earth observation worldwide.

Land cover and vegetation across the world, from NASA GIBS. Each layer carries its own date.

The interactive map needs JavaScript; the layer list and sources are below.

Layers 2

Earth observation, for this page

About this layer
Evidence
Observed
Source
VIIRS NOAA-20 corrected reflectance (NASA LANCE)
Provider
NASA LANCE
Licence
NASA open data
Vintage
daily; Satellite image
Newest at build
2026-10-14
Resolution
about 250 m grid
Uncertainty
Satellite image. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
Reached through
gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
Evidence
Modelled (latest year GIBS publishes)
Source
MODIS Terra and Aqua land cover (MCD12Q1) (NASA LP DAAC)
Provider
NASA LP DAAC
Licence
NASA open data
Vintage
yearly; Satellite classification; latest year GIBS publishes
Newest at build
2024-01-01
Resolution
about 500 m grid
Uncertainty
Satellite land cover classes for the year shown, including croplands; a classification with known errors, not a farm register.
Reached through
gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
Evidence
Observed (clouds leave gaps)
Source
MODIS Terra EVI (NASA LANCE)
Provider
NASA LANCE
Licence
NASA open data
Vintage
daily; Satellite index; clouds leave gaps
Newest at build
2026-10-13
Resolution
about 250 m grid
Uncertainty
Satellite vegetation index for the 8 days to the date shown, a habitat condition indicator; not a measure of species or biodiversity.
Reached through
gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
Evidence
Observed (clouds leave gaps)
Source
MODIS Terra NDVI (NASA LANCE)
Provider
NASA LANCE
Licence
NASA open data
Vintage
daily; Satellite index; clouds leave gaps
Newest at build
2026-10-13
Resolution
about 250 m grid
Uncertainty
Satellite greenness index over the 8 days to the date shown; an indicator of crop and pasture condition, not a yield estimate or a food security warning.
Reached through
gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
Evidence
Observed (clouds and night leave gaps)
Source
VIIRS NOAA-20 NDSI (NASA LANCE)
Provider
NASA LANCE
Licence
NASA open data
Vintage
daily; Satellite detection; clouds and night leave gaps
Newest at build
2026-10-14
Resolution
about 500 m grid
Uncertainty
Satellite detection; clouds and night leave gaps. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
Reached through
gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
Evidence
Observed
Source
GHRSST MUR (NASA JPL PO.DAAC)
Provider
NASA JPL PO.DAAC
Licence
NASA open data
Vintage
daily; Satellite analysis
Newest at build
2026-10-12
Resolution
about 1 km grid
Uncertainty
Satellite analysis. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
Reached through
gibs.earthdata.nasa.gov, only after you allow the live map

Latest available

NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth

Loading the latest NASA imagery.

Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.

Earth observation, framed on the world.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.

Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONET · NASA JPL OPERA DIST-ALERTSources and licences

  • We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
  • We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
  • VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
  • MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
  • GHRSST Level 4 MUR analyses, NASA Jet Propulsion Laboratory; distributed by the NASA Physical Oceanography DAAC (PO.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
  • ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
  • Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
  • © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). ODbL
  • Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
  • Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
  • Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
  • Live: NASA EONET Events are indicative, not authority warnings.
  • Observed (EO): NASA JPL OPERA DIST-ALERT (contains modified Copernicus Sentinel data 2026). We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
  • NASA GIBS: We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
  • Past year, daily temperature and sunshine (NASA POWER): These data were obtained from the NASA Langley Research Center (LaRC) POWER Project funded through the NASA Earth Science/Applied Science Program..
  • Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
  • Optional layers (11 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.

Layers and dates

  • True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
  • Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
  • Enhanced vegetation index, rolling 8 days: MODIS Terra EVI, NASA LANCE · 13 Oct 2026
  • Vegetation greenness (NDVI), rolling 8 days: MODIS Terra NDVI, NASA LANCE · 13 Oct 2026
  • Snow cover: VIIRS NOAA-20 NDSI, NASA LANCE · 13 Oct 2026
  • Sea ice concentration: GHRSST MUR, NASA JPL PO.DAAC · 12 Oct 2026

04Reference practice

Space operations follow UN guidelines and coordination bodies.

ReferenceWhat it sets
COPUOS guidelines for the long-term sustainability of outer space activitiesDebris, space weather and operations
International Charter Space and Major DisastersEmergency data provision
ITU radio regulationsSpectrum and orbit coordination
05Process

How the process runs.

Process

Space systems and satellite services: Earth observation processing chain

Processing levels are mission specific; Sentinel-2 runs from Level-0 raw data to Level-2A, and CEOS Analysis Ready Data sets the minimum for analysis.

  1. 01 Ground segment

    1. 01AcquireSourceSensors acquire optical or radar data. For Sentinel-2 the Level-0 product is raw image data in Instrument Source Packet format.
    2. 03Level-1 radiometric and geometric processingStepLevel-1B gives calibrated top-of-atmosphere radiance. Level-1C adds geometric corrections, including orthorectification, for reflectance.

  2. 02 Pre-processing

    1. 04Level-2 atmospheric correctionStepLevel-2A applies an atmospheric correction to the Level-1C orthoimage. Its main output is a surface reflectance product.
    2. 05Scene classification and masksStepLevel-2A includes scene classification, and Level-1C also makes cloud, cirrus and snow or ice masks. Quality flags travel with the product.
    3. 06Analysis-ready dataDatasetCEOS Analysis Ready Data meet minimum processing requirements and are organised for immediate analysis and interoperability.

  3. 03 Analytics

    1. 02Reference dataDatasetField samples or other independent reference data are used to check the product.
    2. 07Change analysisModelClassification and time-series methods detect change in the analysis-ready data. The method is chosen by the analyst.
    3. 08ValidateGateThe product is compared with reference data and accuracy is reported, for example with a confusion matrix.

  4. 04 Delivery

    1. 09Product to the userDecision · Programme ownerThe producer releases the product with its limits stated.

Neutral outline of a published external standard or method, from its issuing body. Not a record of operation. Nexus does not perform, certify or approve any step shown. A gate or decision belongs to the party the source names. Level-1B and Level-1C add corrections; Level-2A adds atmospheric correction and scene classification.

06In systemic risk work

Satellites as critical infrastructure.

Navigation, timing, communications and observation satellites support finance, power, transport and warnings. Space weather, debris and ground segment failures are risks to all of these simultaneously. Analysis maps which services depend on which constellations and what backup exists.

07Applied in

Platforms that apply this method.

08Stewardship

Who maintains this page.

Space and Earth Observation stewards space systems and satellite services: it keeps this description current and reviews how the method is applied across the platforms.

09Sources

Where this page’s references lead.

The bodies and documents this page is read against. Status and editions change; each link goes to the issuing body.

10Questions

Questions and answers.

Why does one institution host every method page?
GCRI hosts the STEM Commons so that each method has one canonical description. Platforms link to it rather than repeat it, which keeps definitions consistent.
How do I suggest a correction to a method page?
Write to the integrity concern form with the passage and the reason.
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