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How many satellites orbit Earth and why space traffic management is crucial

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How many satellites orbit earth

Have you ever wondered how many satellites orbit the Earth? According to the Union of Concerned Scientists (UCS), which maintains a database of active satellites in orbit, as of April 1, 2020, there were a total of 2,666 satellites in Space, of which 1,918 were in low Earth orbit (LEO).

And this is only till April. Since then we have had many more launches. The busiest among the lot being SpaceX, which has been launching satellites at an average pace of one mission per month this year for its Internet project Starlink. So far, it has launched more than 600 into orbit and has plans of tens of thousands more. Amazon recently announced its plans to launch a mega constellation of 3,000+ satellites to provide Internet connection to under-connected parts of the world. Research firm Euroconsult predicts 2020s to be the decade of small satellites, with an average of 1,000 smallsat launches per year. To put this in perspective, a total of 385 smallsats were launched in 2019.

As satellites get smaller, they are getting easier to build and launch. All this may sound music to some ears, but for a section of experts, this is worrisome.

“Space may appear endless, but opportunities to safely place and maintain an object in Earth’s orbit are not. The risk of collisions between objects in Space is very real, and major collisions have already occurred,” wrote Michael Dominguez, former senior Defense Department official who served as Acting Secretary of the Air Force and DOD Executive Agent for Space. Even one collision can produce a dangerous debris field that can cripple a range of critical capabilities upon which we depend, such as global communications and navigation, and endanger the astronauts stationed in the International Space Station. In addition, the financial consequences could be monumental. 

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That is why Space traffic management is a critical area for governments. In the United States, this has traditionally been managed by the Department of Defense. However, as the number of objects in orbit increased, it was felt that Space situational awareness as a service from Defense was no longer adequate. As part of Space Policy Directive-3, in 2018, the responsibility for Space traffic management activities was transferred to the Department of Commerce. Recently, a Congress-commissioned panel under the National Academy of Public Administration (NAPA) reaffirmed that the Office of Space Commerce at the Department of Commerce was the best suited civil agency to perform such tasks. Dominguez was chair of the five-member panel which also had former NASA Administrator Sean O’Keefe and former NRO Director Martin Faga.

Debris in orbit

UCS’s 2,666 are just the number of active satellites in orbit. There are more than double that number that are dead or lost, and flying around in their orbits incommunicado. Then there is the International Space Station, the Hubble Space Telescope, rocket stages, or even nuts and bolts left behind by astronauts, not to mention the millions of smaller, harder-to-track objects such as flecks of paint and bits of plastic. ESA estimates the total number of Space objects in Earth orbit around 29,000 for sizes larger than 10 cm, 670,000 for sizes larger than 1 cm and more than 170 million for sizes larger than 1 mm!

Any of these objects can cause damage to an operational spacecraft. For example, as per ESA, a collision with a 10-cm object would entail a catastrophic fragmentation of a typical satellite, a 1-cm object would most likely disable a spacecraft and penetrate the ISS shields, and a 1-mm object could destroy sub-systems on board a spacecraft.

While the last large collision of satellites took place in 2009 — when an inactive Russian Cosmos 2251 slammed into the active Iridium 33 over Siberia sending large amounts debris flying into higher and lower orbits — a similar fiasco was closely averted this year on January 30. The two satellites, IRAS and GGSE-4, both belonging to NASA and now defunct, narrowly missed colliding above Pittsburgh.

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Cost of collision

The Organisation for Economic Co-operation and Development (OECD) warns in its recently published report  that economic and societal vulnerabilities to Space hazards, in particular debris, are growing.

For satellites in geostationary orbit, the OECD reveals that such a damage could amount to an estimated 5-10% of the total mission costs, which could be hundreds of millions of dollars. In LEO, the relative costs per mission could be even higher than 5-10%.

However, it warns that the cost of inaction would be far greater. Enough debris in orbit could ultimately lead to the “Kessler syndrome” — a theoretical scenario in which the density of objects in LEO due to Space pollution is so high that collisions between objects could cause a cascade, each collision generating further debris that increases the likelihood of further collisions. OECD says this could be “an ecological tipping point that may render certain orbits unusable”, severely impacting weather forecasting, climate monitoring, Earth sciences and Space-based communications.

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Ensuring safe Space

Then there is the issue of countries conducting anti-satellite tests over the years — the recent one from Russia in July this year that drew condemnation from the US and UK – which further adds to the problem of debris.

Debris removal and collision avoidance are vital for safe Space activities. But as the sky over Earth looks to get crowded, now would be the time to form an independent global organization, with participation from governments, scientists and other relevant stakeholders, to draw up some guidelines and norms to ensure safe Space activities.

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