- In theory, the shortest practical time from spacecraft separation would be about five and a quarter hours, which is half of a geosynchronous transfer orbit. At apogee, which is carefully placed to occur over the equator, a single burn raises the perigee and changes the inclination of the orbit, and you're there.
- See geocaching, geotagging and geodetic coordinates. (2) ( Geostationary Earth Orbit) A communications satellite in orbit 22,282 miles above the equator. At this orbit, it travels at the same speed as the earth's rotation, thus appearing stationary. GEOs are excellent for TV and radio broadcasting, but produce distracting, half-second delays in interactive voice conversations because.
Figure 3 shows some typical results. The figure-eight ground track is that of the geosynchronous orbit (GEO) shown in Figure 2. The geostationary satellite (GSO) sits fixed at the crossover point of the figure eight (over the equator). If we now give the geosynchronous satellite an eccentricity of 0.10, the slanted teardrop shape results. Geostationary orbit Geostationary orbit (GEO) Satellites in geostationary orbit (GEO) circle Earth above the equator from west to east following Earth’s rotation – taking 23 hours 56 minutes and 4 seconds – by travelling at exactly the same rate as Earth. This makes satellites in GEO appear to. GEO is a circular geosynchronous equatorial orbit, and GSO satellites would have their semi-major axis at exact distance to Earth as GEO has. So while not exactly the same thing, they are of course still relevant to you question, and indeed they all repeat also in the list of GEO satellites by Eric Johnston.
NOAA’s Geostationary and Extended Orbits (GEO-XO) satellite system is the ground-breaking mission that will advance Earth observations from geostationary orbit. GEO-XO will supply vital information to address major environmental challenges of the future in support of U.S. weather, ocean and climate operations.
The GEO-XO mission will continue and expand observations provided by the GOES-R Series. GEO-XO will bring new capabilities to address emerging environmental issues and challenges that threaten the security and well-being of every American.
NOAA is working to ensure these critical observations are in place by the early 2030s as the GOES-R Series nears the end of its operational lifetime.
Advancing NOAA’s Mission
GEO-XO will watch over the Western Hemisphere as part of a NOAA observing system that provides world-class environmental information to support both long-term planning and short-term response. This observing system will power increasingly sophisticated models that forecast climate-change-driven weather patterns never seen before.
The GEO-XO satellites will also host space weather instruments and its ground system will provide services for NOAA’s deep space weather satellites.
With GEO-XO, made-to-order data delivery will allow users to customize data access to facilitate more accessible and usable environmental information. Multiple data delivery options will be available, including an internet storefront, mobile device access, and satellite broadcast. Cloud-based product generation will expand data access, increase community involvement, and continuously evolve service.
New and Improved Observations
New technology and scientific advancements will improve observations for weather forecasting and provide new ocean and atmospheric measurements. GEO-XO will provide real-time, high-resolution visible and infrared imagery for monitoring Earth’s weather, oceans, and environment. Data from GEO-XO will contribute to weather forecast models and drive short-term weather forecasts and severe weather warnings. GEO-XO will also provide advanced detection and monitoring of environmental hazards like wildfires, smoke, dust, volcanic ash, drought, and flooding.
Additional observations are recommended to address our changing planet and evolving user needs. NOAA plans to incorporate day/night visible imagery, infrared sounding, atmospheric composition, and ocean color, as well as an improved lightning mapper in the GEO-XO system, pending program approval. These observations will provide vital data to complement those from NOAA’s partners in Europe and Asia, building a critical global observing system.
User Needs Inform GEO-XO Capabilities
NOAA, its users, and industry partners conducted a number of capability studies, observation simulation experiments, value assessments, future scenario evaluations, societal and economic benefit evaluations, and user needs workshops, surveys, and interviews to determine which observations are the highest priority for GEO-XO to provide.
GEO-XO Core Capabilities
Visible/Infrared Imagery
Data continuity; spatial and spectral resolution improvements
Solar and Space Weather Monitoring
Data continuity (GEO-XO to accommodate space weather instruments)
Data Collection System Ingest
Service continuity
Data Collection System (DCS), Emergency Managers Weather Information Network (EMWIN), High Rate Information Transmission (HRIT) Data Rebroadcast
Service continuity; potential use of commercial services
GEO-XO Recommended Capabilities
Lightning Mapping
Data continuity; spatial resolution improvements
Infrared Sounding
New capability for numerical weather prediction and nowcasting
Day/Night Imagery
New capability for nighttime cloud, fog, and smoke tracking
Ocean Color Imagery
New capability for ocean health and productivity monitoring
Atmospheric Composition Measurement
New capability for detection of air quality threats
Sustaining a Weather-Ready Nation
Visible and Infrared Imagery
High-resolution imagery is the backbone of Earth observations. The GEO-XO imager will improve upon the GOES-R Advanced Baseline Imager by providing more detailed observations and more precise tracking of severe weather. GEO-XO will also detect wildfires four times smaller, potentially increasing lead time to respond to a blaze before it gets out of control. Additional channels will better detect water vapor in the atmosphere.
Day/Night Visible Imagery
Nighttime visible imagery from geostationary orbit will dramatically improve the ability to detect and track fog at night, characterize the formation of tropical storms, monitor power outages/recovery in real-time, provide a new lights-based search and rescue utility, and introduce the ability to detect and track air quality and visibility hazards such as smoke and dust at night.
Lightning Mapping
Lightning mapping from geostationary orbit improves severe storm analysis, lightning hazard detection, hurricane intensity prediction, wildfire response, and precipitation estimation, and mitigates aviation hazards. A GEO-XO lightning mapper will potentially improve resolution over the GOES-R Geostationary Lightning Mapper.
Infrared Sounding
A GEO-XO infrared sounder will provide real-time, information about the vertical distribution of atmospheric temperature and water vapor to feed advanced numerical weather prediction models and improve short-term severe weather forecasting.
Supporting Healthy Oceans, Resilient Coasts, and Climate Science
Atmospheric Composition
Atmospheric composition measurements from geostationary orbit will improve air quality monitoring to mitigate health impacts from severe pollution and smoke events.
Ocean Color
A GEO-XO ocean color imager will provide observations of ocean biology, chemistry, and ecology to assess ocean productivity, ecosystem change, coast/inland water quality, and hazards like harmful algal blooms.
Recommended GEO-XO Constellation
NOAA evaluated a range of space architecture options to select one that will provide the highest priority observations effectively and efficiently. The imager, lightning mapper, infrared hyperspectral sounder, and ocean color instrument are best suited on two spacecraft near the current GOES-East and GOES-West positions, while the atmospheric composition instrument is recommended to reside in a central location. A day/night band, or channel, is recommended as part of either the imager or the sounder.
A combination of NOAA and commercial host spacecraft will support all recommended observations in desired orbital locations in the most cost effective configuration. The selected constellation includes an imager, sounder, and ocean color instrument on a NOAA spacecraft in the east and west positions, lightning mapper on a hosted spacecraft in east and west, and atmospheric composition on a hosted spacecraft in the center.
The NOAA GEO-East and GEO-West spacecraft will also carry NOAA Space Weather Program-provided instruments. These include a solar ultraviolet imager, irradiance monitor, coronagraph, magnetometer, and energetic particle detectors.
Below is the recommended GEO-XO constellation as of January 27, 2021. This constellation is preliminary, pending program approval.
GEO-XO Timeline
NOAA assessed user needs and studied a variety of potential observational capabilities. These analyses will inform key decisions to be made in 2021. Once the GEO-XO requirements are defined, pilot studies will lead to the preliminary design of the spacecraft and instruments. As the program moves into the critical design stage, NOAA will begin preparing data users for new capabilities the GEO-XO system will provide. The first GEO-XO launch is planned for the early 2030s and will maintain and advance NOAA’s critical geostationary observations through 2055.
Collaboration Delivers the Mission
GEO-XO is a NOAA program, supported by NASA. NASA will manage the development of the satellites and launch them for NOAA, which will operate them and deliver data to users worldwide.
Industry partners are critical to meeting the mission. NOAA and NASA will work with commercial partners to design and build the GEO-XO spacecraft and instruments. Instrument definition and design development studies are underway.
GEO-XO procurement notices
- November 20, 2020: GEO-XO Imager Phase A Study Request for Proposals
- January 14, 2021: GEO-XO Lightning Detector Focal Plane Array Request for Information (RFI)
- February 3, 2021: GEO-XO Sounder GXS Request for Information (RFI)
Geoorbital
Phase A studies
NASA will award a number of contracts for “Phase A” studies as part of GEO-XO instrument formulation activities. These definition-phase study and development contracts will help define each instrument’s potential performance, risks, costs, and development schedule.
On March 31, 2021, NASA awarded GEO-XO Imager (GXI) Phase A study contracts to L3Harris Technologies, Inc., and Raytheon Company. Each company will conduct a one-year study to develop an infrared and visible imaging instrument concept and mature necessary technology.
Download the PDF version of the GEO-XO fact sheet.
This information is subject to change as the GEO-XO program develops.
Advantages of LEO Orbit | disadvantages of LEO Orbit
This page covers advantages and disadvantages of LEO Orbit. It mentions LEO Orbit advantages and LEO Orbit disadvantages.LEO stands for Low Earth Orbit.
There are three main types of orbits viz. LEO, MEO and GEO based on distances from lowest to the highestfrom the Earth.There are orbits around the earth where satellites are installedafter their launch.Following are the features of LEO orbit.
• Orbit period: 10 to 40 minutes
• Orbit height from Earth: 500 to 1500 Km
• Life of satellite in the orbit: Short
• Propagation loss in the orbit: Least
• Number of satellites to cover entireregions on Earth: 40 to 80
The figure-1 depicts LEO (Low Earth Orbit).
LEO vs MEO vs GEO andsatellite basics for more information.
Advantages of LEO orbit
Following are the advantages of LEO orbit:
➨As it is near to the earth, LEO satelliteslaunced in LEO orbit provides better signal strength. Henceless power (about 1 watt) is needed for transmission.
➨It has least propagation delay (about 10ms) compare toother orbits due to closeness to the Earth.Due to lower latency, it can be used for realtime time criticalapplications.
➨It eliminates need for bulky receiver equipments due tohigher C/N signal ratio.
➨Low price satellite equipments are sufficient forground stations.
➨Better frequency reuse can be achieved due to smaller footprints.
➨It provides high elevation for polar regions of the Earth.Hence better global coverage can be achieved.
Disadvantages of LEO orbit
Following are the disadvantages of LEO orbit:
➨As it is at lesser distance above the Earth,it covers less region of the earth. Hencelarge number of satellites are needed to cover the entireregion of the Earth. Hence the installation of such LEObased system is costly.
➨As LEO satellites move constantly and hence service is beinghanded off by each satellite to the next one inthe constellation. Hence succession of satellites are required tocover any region on the Earth.
➨Atmospheric effects are more and hence willcause gradual orbital dis-orientation of the satellites.This requires regular maintenance of satellites to keepthem on track in the LEO orbit.
➨It is only visible for 15 to 20 minutes fromparticular area of the Earth. Hence there is lesstime available for testing and troubleshooting activities.
➨Efficiency to serve populated region is less compare to GEO satellites.
➨Ground station is very complex as it requires to handle frequent handoffsbetween LEO satellites.
➨The complete deployment of LEO constellation is essential tostart the service to the customers. Hence it requires more time to providethe satellite service & mass adoption by the users compare to GEO.
➨LEO satellites have shorter life span (about 5 to 8 years)compare to GEO satellites (about 10 years).
Also refer advantages and disadvantages of MEO >> and GEO >>.
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