Friday, April 19, 2024

Satellite Mega Constellation For Technological Breakthroughs

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Earlier this month , some  people claimed  a march  of star-like objects passing across the night sky. Their observations could not claim any  extraterrestrial activity , or even astrophysical one.Actually it was a line of satellites, recently launched by SpaceX. It  eventually  joined  many more to form Starlink, which  resulted in the entry of  “mega constellation”. Such systems  rotate around the Earth as a global network designed to beam high-speed internet to users anywhere in the world.

Types And Applications Of Mega Satellite Constellation

Depending on the orbital altitude , there are three different types of satellite constellations: GEO, MEO, and LEO. Each type can be used for a specific purpose.

GEO Satellite Constellation

GEO stands for a Geostationary (or geosynchronous equatorial)  Earth Orbit that hosts hundreds of satellites nowadays. Geostationary swarms derived their name from their Earth-rotation mode. They synchronise with our planet’s movement, thus hovering all the time over the same point. It happens because GEO swarms fly over the equator, and each rotation takes 24 hours. GEO is a typical orbit for weather forecasting, TV broadcast and  low-speed communication services. At an  altitude of 36,000 km, an individual GEO satellite can capture 40% of the Earth’s surface. Thus, a group of three units 120 angular degrees apart is enough to keep an eye on the whole world.

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MEO Satellite Constellations

Operating at the altitude of 5,000 to 20,000 km Medium Earth Orbit swarms ,traditionally used  for navigation purposes. MEO constellations also provide high-bandwidth connectivity in locations where terrestrial infrastructure is poor or not feasible. This particular refers to maritime and aerospace industries, offshore platforms, and rescue team operations in remote areas.

LEO Satellite Constellations

Operating at an altitude of 500 to 1,200 km , Low Earth Orbits(LEO) swarms make up the densest space population. The derived data is widely used by governmental bodies, as well as commercial and non-commercial organisations. LEO satellite constellations primarily support research, telecommunication. Further they can be deployed in environmental monitoring, disaster response, forestry, and agri-sectors.

 Such swarms may have circular or elliptical orbits . Circular orbits are at the same altitude, while elliptical orbits contain the apogee (the highest point) and the perigee (the lowest one). Swarms with circular orbits revolve around our planet within 1.5 to several hours and typically fly nearly above the geographic poles. As for elliptical orbits, they are passed slower at the apogee and faster at the perigee points.

Such mega satellite constellations belong to Starlink, OneWeb, Iridium, GlobalStar, RapidEye, and other operators.

Hybrid mega satellite constellations

It combines satellites  travelling on different orbits, e.g. MEO+GEO, LEO+MEO, etc.

Nanosatellite constellations

Formed by CubeSats (miniaturised satellites made of cubic modules), they offer the communications infrastructure to facilitate the loT in space. Such constellations are vital as they offer more equipment to process the enormous data demands of the IoT. Undoubtedly, the use of underground (and undersea) fibre optic cables on Earth alone will always have limitations in Internet communications.

Advantages and Disadvantages

Advantages:

  • Global connectivity.
  • Cheaper components : Unlike single satellites , such constellations are comparatively cheaper.
  • Lesser signal transmitting time.( downlink and uplink )
  • Enhance capacity even in remote areas.
  • Relationships between these satellites to improve each other’s qualities ( complementarity ) greatly helps in case of failure of one or more.

Disadvantages:

  • Space junk hazard.
  • Light pollution: They obstruct the natural dark sky during night time.
  • They obstruct astronomical studies.

Focus On The Global Scenario

The term mega-constellation describes a constellation consisting of several hundreds or thousands of satellites orbiting Earth. The most remarkable plan is StarLink  with its plan to deploy a staggering 42,000 satellites in Low Earth Orbit (LEO).

As of July 2023, there are 4,519 StarLink satellites in orbit, of which 4,487 are operational, according to Astronomer Jonathan McDowell who tracks the constellation on his website.

In 2019, the SpaceX company  took an aggressive decision.Result was ” StarLink “.  Presently it is providing satellite Internet access coverage to over 56 countries. It also aims for global mobile phone service after 2023.

Other top key players of satellite mega constellations are:  TeleSat and OneWeb. E- commerce company Amazon has also presented a proposal for its Kuiper System constellation. It consists of 3,236 satellites using Ka-band at altitudes of 590, 610 and 630 kilometres.

China is preparing to deploy 13,000 satellites for its LEO broadband mega constellation ( called ” Guowang”) to beat Starlink and other western ventures. Today China is capable of producing hundreds of satellites per year.

New-age space startups are emerging in India. Isro is heading towards space industry 4.0.Space mining, in -space manufacturing , in orbit servicing , international space station, space tourism and space entertainment are some of the  areas where India is dreaming of its growth. However it is still lagging behind  in the satellite mega constellation area. Isro’s rockets have recently put satellites in LEO for private companies such as OneWeb to build their mega constellations.

 Construction of such constellations have begun over the past 18 months .These constellations are still in their infancy , but are growing rapidly. It is estimated that over 1,00, 000 new satellites for this purpose are planned to be launched during the remainder of the current decade. These loomed activities are surpassing space communication capabilities.Mega constellations are said to have much impact in 6 G network.

Conclusion

Over the past few years , the world has experienced emergence of a larger number of space startups , increased cooperation between international intergovernmental and non- governmental organisations and expansion of commercial projects in the field of space applications. These factors further added to the rise of satellite mega constellations.

Human beings always relied on the heavens for comfort and inspiration. Modern satellite constellations are changing the picture of our natural constellations that our ancestors watched in wonder for long hours. No doubt such constellations are inspiring creative thoughts of techno scientists. But casual skywatchers to astrophotographers to professional astronomers are greatly worried about activities of SpaceLink and others.

References:

  1. Article “Satellite Constellations: Existing And Emerging Swarm ” by Kateryna Sergieieva .
  2. Article ” What is a Satellite Mega Constellation ? Advantages and Disadvantages ” by Soumya Rawat.
  3. Articles published by Forbes related to  space activities .
  4. Several other web pages are also referred to .

Vinayak.R. Adkoli served as lecturer in three different polytechnics for 10 years. I am also a freelance writer and cartoonist.

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