GoldenGolden
Low Earth orbit satellites

Low Earth orbit satellites

Low Earth orbit satellites are any satellite developed to orbit in a low Earth orbit for imaging, internet connectivity, and meteorological applications.

Low Earth orbit (LEO) satellites are satellites in an orbit described as a low orbit, meaning the altitude is usually less than 1000 kilometers and can be as low as 160 kilometers above Earth. This LEO range is low compared to other orbits, but most commercial aircraft do not fly at altitudes greater than 14 kilometers. The best examples of LEO satellites include: the Hubble space telescope, the International Space Station, the Spot family of satellites, and military observation satellites.

Low Earth orbit

The Low earth orbit is often described as orbits below 2,000 kilometers (1,200 miles) and as low as 160 kilometers. When below 450 kilometers in altitude, the orbit can be classified as a very low Earth orbit (VLEO). The low Earth orbit makes it useful for various applications that benefit from the proximity to Earth. Most satellites in a LEO travel at a speed around 7.8 km per second, which means a satellite takes 90 minutes to circle Earth. Unlike satellites in geostationary or geosynchronous orbits, LEO satellites do not have to follow a particular path, such that their plane can be tilted, which consequently makes available more routes for satellites in LEO.

Factors in the choice of altitude include the radiation environment and the amount of space debris at that particular altitude. At many LEO altitudes, there is no significant debris and the radiation environment is relatively benign, which means the necessary radiation shielding is not needed, and satellites in this orbit can be manufactured at a lower cost than their higher altitude peers.

Types of orbits

Orbit
Description

Geosynchronous orbit (GSO) and geostationary orbit (GEO)

Orbits matching the Earth's sidereal rotation period.

High Earth orbit

A geocentric orbit above the altitude of geosynchronous orbit (35,786 kilometers or 22,236 miles).

Low Earth orbit (LEO)

Orbits with altitudes below 2,000 kilometers (1,200) miles.

Medium Earth orbit (MEO)

Geocentric orbits ranging in altitude from 2,000 kilometers to below a geosynchronous orbit at 35,786 kilometers (22,236 miles). This is also known as an intermediate circular orbit and often used for Global Navigation Satellite Systems, such as GPS, GLONASS, Galileo, and BeiDuo.

Polar orbit and sun-synchronous orbit (SSO)

Orbits which travel past Earth from north to south rather than east to west, passing roughly over the Earth's poles and are synchronized to be always be in the same 'fixed' position relative to the sun.

Transfer orbits

A specialized kind of orbit to move a satellite from one orbit, usually when they are released from a launch vehicle, to their final orbit. This is usually achieved through small built-in motors.

Image of different orbit types.
Very low Earth orbits (VLEO)

The very low Earth orbit (VLEO) is typically classified as an orbit below approximately 450 kilometers in altitude and encompasses the lower part of the low altitude orbit. VLEO orbits have the potential to provide benefits to spacecraft operating in higher altitude orbits. The VLEO orbit offers improved spatial resolution, and the satellite can be manufactured with mass and volume savings while maintaining optimal performance. And, for radar and lidar systems, the signal-to-noise ratio can be improved with a VLEO orbit. Benefits include improved geospatial position accuracy, improvements in communications link-budgets, and greater launch vehicle insertion capability.

Low Earth orbit satellite construction
Example of a low Earth orbit satellite.

Often low Earth orbit satellites are used in constellations. Because of their rapid speed, a constellation allows a single satellite to pass along a workload to a following satellite in order to maintain service over a specified area. In order to develop these constellations, the satellites often need to be small and low-cost, and the lower orbits in turn help build these smaller satellites. In lower orbits the satellites do not require the same powerful amplifiers of other satellites in order to transmit signals. Due to the low radiation environment in LEO, the need for expensive radiation shielding of electronic parts allows for the lower cost of manufacturing these satellites. The reduced cost means launching a satellite into LEO is around USD$5,000/kg. More traditional, heavier satellites can cost at or greater than USD$7,000 per kilogram. The low cost of construction is also important as satellites age out, their orbits degrade, or they are damaged by debris or other collisions.

Starlink satellite launch seen from Earth.

With developing satellite constellations, the satellites can include a phased array with RF beamforming and an embedded channelizer—a digital baseband processor for operators of a network of thousands of low earth orbit satellites, which allows these satellites to steer their beams. Being capable of steering beams allows a satellite constellation to steer to an area in need of more bandwidth, and generally away from an area where less bandwidth is required. Traditional geosynchronous satellites broadcast with a large fixed beam bandwidth without the ability to switch the beam or bandwidth.

Navigation

In order to keep costs down, there is a suggestion of manufacturing LEO satellites with internal shifting masses, which would shift the center-of-mass and in turn shift the location of the spacecraft through modulating, in direction and magnitude, the aerodynamic torques which allows the satellite reject aerodynamic disturbances. As well as developing navigation systems, engineers of satellites are working to develop and test advanced materials which can work to use atmospheric flow to control orientation and use an electric propulsion system which use the residual atmosphere as a propellant. These systems are intended to develop satellites with the potential to keep the satellites in orbit indefinitely despite drag.

Low Earth orbit satellites for Imaging

LEO satellites are used for different imaging applications, because a satellite flying at a lower altitude can improve the resolution of optical sensors, radiometric performance (infrared or microwave sensors), and geospatial accuracy. Those sensing benefits can also reduce payload size - optical, radar, or communications systems - and overall cost. For example, Earth Observant's "Stingray" imaging satellite, a VLEO satellite, flies almost within Earth's atmosphere which can provide a significant improvement in imaging categories. However, this low altitude also comes with downsides, including aerodynamic drag and strong gravitational pull that is significant enough to make an orbit decay in less than five years.

Imaging for monitoring weather

Part of the usefulness of LEO satellites is imaging for monitoring weather. This is especially useful in a polar orbit or sun synchronous orbit rather than a GEO orbit. Often satellites in a sun synchronous orbit are operated in pairs with one making a morning pass and the other making an afternoon pass to ensure every spot on the Earth is observed at least every six hours and often every four hours. The passive microwave imagery capable on LEO satellites is also capable of seeing through non-raining clouds and viewing rainbands, eyewalls, and storm eyes even when obscured by upper-level clouds. This can provide good data and information on precipitation and clouds at low and medium levels and can give important details concerning the intensity and position of storms.

Example of imagery produced by the National Oceanic and Atmospheric Administration (NOAA)'s low Earth orbit satellites.
Imaging for air traffic management

Along with more traditional navigation systems, low Earth orbit imaging satellites offer benefits for space utilization in air traffic control management. These benefits can include the development of more efficient air traffic routes to reduce travel times, which in turn reduces the amount of carbon dioxide emissions through the commercial airspace industry. Further, these low Earth orbit satellites can track commercial aircraft in remote areas or air traffic blackout areas.

Imaging for environmental monitoring
Example of air quality monitoring from a low Earth orbit satellite.

The use of low Earth orbit satellites for imaging can also be used for environmental monitoring across a broad spectrum of environmental parameters, and with improved capabilities and reduced latencies to better serve environmental monitoring needs. Satellites in polar orbits and lower inclination orbits can also add new and different data compared to traditional satellite environmental monitoring and imaging.

Low Earth orbit satellites and navigation

A traditional navigation system, such as the Global Position System, is a component of systems including power grids, wireless communications, and aircraft management. Traditional systems are based on GEO satellites. With the increase of satellites in low Earth orbit, there is a chance to include payloads allowing those LEO satellites to act as navigation satellites. The number of satellites can provide better geometry than GPS, and the lower radiation environment also means lower cost components for the navigation. Further, using a low Earth orbit can reduce path loss and make navigation systems more resilient than jamming.

As well, because a lot of LEO satellites use different frequency bands, the data provided to navigation systems can be changed to applicable bands depending on the area. These systems can be paired with traditional GPS satellite data. Meanwhile, similar to the promise of broadband internet provision to remote or rural areas, those areas where GPS systems are less reliable can be serviced by LEO satellites.

Low Earth orbit satellites and internet

One of the more well-known use cases for low Earth orbit satellites is the possibility of delivering high-speed internet coverage for clients such as governments, mining corporations, residences, and shipping conglomerates in regions where they lack internet infrastructure, and therefore access to the internet. Contrasted with satellites in a geosynchronous orbit, LEO offers a shorter and faster trip for an internet signal, and thereby reduces latency. As well, since signals can travel rapidly through the vacuum of space when compared to fiber-optic cables, LEO satellites have the potential to rival or exceed ground-based networks. SpaceX has largely driven the popularity of LEO satellite-delivered internet. As of March 2021, SpaceX has launched 1,500 of their Starlink satellites. Meanwhile, China Aerospace Science & Industry Corp. has proposed a network of 156 satellites, and Amazon has requested permission to launch 3,236 satellites.

Service expectations

With internet delivery by signal, the expectation (especially for widespread user adoption) is that the signal latency will be near or similar to that offered by fiber-optic internet delivery. OneWeb, a London-based company, launched a washing machine-sized LEO satellite with an average latency of 32 milliseconds, in July 2019. SpaceX has stated publicly that they are aiming for an initial latency target of 20 milliseconds, which they hope to halve as more satellites are delivered. Expectations around video streaming and conferencing will also need to be considered. OneWeb has already demonstrated live, full high-definition streaming video, and Telesat has demonstrated videoconferencing services. With the advent of 5G, delivery speeds with high bandwidth and low latency should improve and offer new avenues for the use of satellite internet for smart cars and IoT technology in remote areas.

Considerations

One consideration with the advent of LEO satellites delivering internet will be user terminal pricing and availability, such that these terminals should be reliable and physically robust, while also being easy to install and use. There is also the question of whether the LEO satellite internet providing industry will see expansion or consolidation; this would be either regulatory bodies allowing companies to launch individual satellite constellations, or much like current telecom towers, constellations would be required to carry multiple service providers. This consideration also includes the increasing regulations in satellite constellations, especially with the risk of orbital debris. These possible regulations could be around deployment rate, frequency allocation, orbital debris mitigation, and de-orbit procedures. Another consideration for the development of LEO satellite internet provider constellations would be the possibility of service interruptions in the case of orbit degradation or collisions with other satellites or debris and how those will be handled.

Satellite IoT

Satellite IoT have been used for a while with traditional mobile sat systems (MSS) dominant in the M2M or IoT market, using an L-band spectrum and with a focus on mobile and maritime applications. As well, fixed sat systems (FSS) have developed M2M and IoT services over Ku or Ka band, with higher bandwidths well-suited to satellite-based IoT and backhaul services connecting terrestrial local area IoT networks from high density sensor networks to the internet.

Low Earth orbit satellite IoT

Newer low Earth orbit satellites offer reduced costs compared to traditional satellite IoT solutions, based on new cubesat technology (which uses a range of UHF, VHF, S-band, and Ku-band services) and lower power modems to connect to ground sensors. These orbits also do not have the level of capex burden that incumbent satellite network operators have been saddled with as well. The use of satellite IoT can offer connectivity services for transportation and logistics services, including while at sea or in remote areas. These satellite IoT connectivities for navigation and logistics can be used for environmental monitoring systems, air traffic control infrastructure, agricultural monitoring and connectivity, and disaster management services. There are two main type of IoT connectivity services pathways:

Gateway services
Direct satellite and satellite gateway services visualization.

Comparable to GSM or WiFi backhaul service, the IoT gateway backhaul over satellite emerges as a new application. This is through the low-cost terrestrial radio transmission standards for IoT such as LoRa, Sigfox, LTE-M, or NB-IoT. These networks come with low-cost gateways and low-cost, low orbit satellites to increase their possible reach.

Direct to satellite services

This type of service, especially with low-cost and low-power options, is ideal for wide area sensor networks, with sensors dispersed over a geographical territory. This service is especially important in remote areas where the low possible cost can enable massive networks with new data points to feed data analytics in a range of industries. With the increase in reliability and the decrease in latency, the direct to satellite services have become more valuable. Services can include tracking, tracing, logistics, insurance, and performance monitoring for remote assets. As well, they can enable new applications such as:

  • Process monitoring and grid management in the energy sector
  • Asset management in the mining sector
  • Wide area monitoring applications for public structure monitoring
  • Monitoring in smart agriculture for food, water, environment, and security

Low Earth orbit satellite IoT applications

Application
Description

Agriculture

Especially within natural resources, applications can rely on imagery and satellite navigation applications, including IoT communication between autonomous or monitoring systems, with a focus on precision agriculture.

Air Traffic Control

Similar to other infrastructures, this mixes satellite communications and satellite navigation solutions to allow greater tracking and communications between aircrafts and control towers.

Disaster management

This relates to sovereignty and security with overlapping applications for imagery, satellite communications, satellite navigation, and covers disaster mitigation, relief, and search and rescue activities.

Environments monitoring

This application uses imagery, satellite communication, and satellite navigation in order to enable and enhance ecosystems monitoring, ice monitoring, and aspects of corporate social responsibility for industries such as oil and gas and mining.

Remote and rural communities

This largely addresses the internet infrastructure in these areas, where the utilization of satellites can provide broadband internet services to these communities.

Transportation and logistics

Similar to disaster management and air traffic control, this larger application relates to the use of satellite IoT connectivity for any remote areas, such as maritime transportation or land transportation and refers to satellite communications and satellite navigation systems.

Low Earth orbit satellites and military applications

Low Earth orbit satellites have found use in intelligence, surveillance, and reconnaissance (ISR) applications. These systems include image intelligence (IMINT), signals intelligence (SIGINT), and measurement and signatures intelligence collection systems (MASINT). These systems provide photographic coverage over denied territory, geodetic positioning of platforms emitting at radio frequencies, and have been used for early warning systems for strategic intercontinental ballistic missiles. With their lower altitude and faster traveling speed, they have been used for defending against shorter-range ballistic missiles and for estimating launch points to enable counter-attacks against mobile targets.

Outside of imaging and detection, the use of LEO satellites have been tested for improving long-range precision fire of missiles and missile defense systems. With signal sourcing capabilities, these satellites offer a chance for the military to understand where jamming and spoofing is originating from, in order to increase their situational awareness.

Military constellations

A major question for the continued development of LEO satellites for military use is whether the military will develop and launch their own LEO satellite constellations, or if they would include military assets and payloads on commercial LEO satellites in order to reduce the overall cost of military applications while simultaneously improving the resiliency of military operations in space.

Earth Observant's conceptual overview of it's Stingray imaging satellite constellation.

Earth Observant won a development contract with the Air Force's AFWERX to advance the company's design for a small, very low Earth orbital optical imaging satellite—the company's Stingray satellite. These satellites present a chance for reduced signal interruptions and reduced possibility of collisions while offering faster signal processing, beneficial for the sometimes quick-paced nature of military operations. Furthermore, to offer greater benefit to the military, these satellites work to offer near real-time imagery to Air Force or Army use. This is done through the on-board processing of raw optical data using edge computing methods rather than sending the raw data to a ground station to be processed.

Project Blackjack

In April 2020, Lockheed Martin was awarded a $5.8 million contract for the first phase of a satellite integration on DARPA's Blackjack program. This program looks at the proliferation of LEO constellations and the development of surrounding technology for the commercial space and works to bring those to achieve a number of military goals. The program is also a shift toward on-orbit processing, where the Blackjack constellation can carry the processing burden of ground-based systems.

Partnerships in low Earth orbit satellites

Partnering companies
Announcement of partnership
Description of partnership

2020

Funding from AFWERX for the development of military imaging LEO satellites

Parnership for the construction of satellites for OneWeb's services.

2021

A partnership for Arianespace to carry and deploy OneWeb's LEO satellites into orbit.

Partnership to develop a 5G network and broadband network with LEO satellites.

2020

Partnership for assisting Facebook with the development of high bandwidth for LEO satellite internet provision from Facebook.

2020

Partnership to help both companies develop LEO broadband and remote sensing platforms.

2020

Part of DARPA's Project Blackjack, the partnership is for the development of LEO satellites for military use and the development of a military constellation.

2021

Partnership to help Lockheed Martin develop a space-based 5G network.

2015

Partnership for MDA to provide OneWeb with antenna and payload design

Partnership to develop remote sensing equipment for multiple temporal and spatial resolutions.

2020

A partnership to help SpaceX track Starlink satellites and stop collisions.

2020

Known as Azure Space, the partnership is to bring Microsoft's cloud computing services to the SpaceX network of satellites.

2020

Partnership to launch Telesat's satellites on Blue Origin launch vehicles.

2020

Partnership between both companies to improve operational efficiencies for LEO satellites in communications.

2021

Partnership for Thales Alenia Space to manufacture the satellites for Telesat's satellite constellation.

2021

Apollo Fusion has been selected by York Space Systems to supply the propulsion system for their low Earth orbit satellite constellation program.

2020

This partnership sees LatConnect60 chosen as a subcontractor and strategic partner for the development of a satellite constellation for critical Earth observation.

Investments into low Earth orbit satellites

In addition to grants, partnerships, and project money, there is a large investment in low Earth orbit satellite companies, especially those working to expand broadband, imaging, or IoT services. However, many of the venture capital firms investing in the LEO space are internet- or software-focused firms, as opposed to firms which are more familiar with space investments and therefore have deep knowledge of the sector.

Timeline

March 29, 2021
Future OneWeb LEO broadband satellites may adopt laser links
March 29, 2021
Fleet Space launches fifth IoT nanosatellite
March 29, 2021
China's first LEO satellite system for IoT to be completed in 2021
March 29, 2021
SpaceX is first with inter-satellite laser links in low-Earth orbit
March 29, 2021
York Space Systems picks Apollo Fusion for LEO constellation
March 28, 2021
SpaceX's use of low Earth orbit likely increases collision risk
March 28, 2021
OneWeb to launch broadband services in Canada by end of the year
March 27, 2021
Arianespace deploys OneWeb constellation satellites
March 25, 2021
OneWeb launches thirty six satellites from Russia to extend internet orbit
March 23, 2021
Lockheed Martin partners with satellite start-up Omnispace to build a space-based 5G network
Page 1 of 4

People

Name
Role
LinkedIn

Further reading

Title
Author
Link
Type
Date

5 FAQs About Low Earth Orbit (LEO) Satellite Constellations

Rob Rutkowski

Web

June 29, 2017

Amazon planning 3,236-satellite constellation for internet connectivity - SpaceNews

Caleb Henry

Web

April 5, 2019

Amazon will launch thousands of satellites to provide internet around the world

Jon Porter

Web

April 4, 2019

Army looks to leverage 'low Earth orbit' satellites

Gary Sheftick

Web

March 9, 2020

Attitude Stabilization of Spacecraft in Very Low Earth Orbit by Center-Of-Mass Shifting

Josep Virgili-Llop, Halis C. Polat, Marcello Romano

Web

February 14, 2019

Avnet: Quality Electronic Components & Services

Avnet Silica

Web

June 27, 2019

Case Study: Low Earth Orbit Satellite - SRI International

Web

September 2019

Five key uncertainties around high-speed Internet from low Earth orbit

David Jarvis

Web

August 18, 2020

LEO constellation optimization for LEO enhanced global navigation satellite system (LeGNSS)

Haibo Ge, Bofeng Li, Liangwei Nie, Maorong Ge, Harald Schuh

Web

August 1, 2020

Satellite tech takes connectivity into new dimensions

Guglielmo S Aglietti

Web

September 10, 2018

Socio-economic benefits of space utilization

Adam Keith

Web

September 7, 2018

Space needs to be regulated before humans ruin it - CNN

Greg Wyler

Web

July 22, 2019

Telesat taps Thales Alenia Space for $3 billion deal to build low earth orbit satellites

Steve Scherer

Web

February 9, 2021

US military may start moving towards launching fleets of tiny satellites

Elizabeth Howell

Web

April 1, 2020

Will Low Earth Orbit Satellites Fly Under the Privacy Radar

Neil Lappage

Web

January 4, 2021

Documentaries, videos and podcasts

Title
Date
Link

Attack Vectors in Orbit: The Need for IoT and Satellite Security

May 16, 2019

Decoding Orbcomm Satellite Transmissions Using Software Defined Radio

January 1, 2021

Direct-To-Satellite Internet of Things (IoT) - Overview, Status and Challenges

December 16, 2019

Earth Observant Overview for Air Force

April 29, 2020

How Low Earth Orbiting Satellite Systems Work

September 21, 2011

Why SpaceX And Amazon Are Launching 42,000+ Satellites

December 16, 2019

Companies

Company
CEO
Location
Products/Services

News

Title
Author
Date
Publisher
Description
OneWeb
April 23, 2021
www.prnewswire.com:443
/PRNewswire/ -- OneWeb, the global communications network powered from space, today announced the launch of its first Innovation Challenge, an invitation to...

References

Page 1 of 8
...
Golden logo
Text is available under the Creative Commons Attribution-ShareAlike 4.0; additional terms apply. By using this site, you agree to our Terms & Conditions.