What is space junk and why is it a problem?

December 14, 2018


Dennis
Wong
Low Earth orbit (LEO) is becoming increasingly cluttered after 60 years of continuous rocket and satellite launches. Even the tiniest piece of debris, orbiting at speed, can pose a major threat to the International Space Station and active satellites. China is one of the many countries responsible for the mess

China is expanding its influence in space and is usually ranked among the worst offenders when it comes to producing space debris. Earlier this month, China launched a rocket carrying Chang’e 4, a lunar lander and rover spacecraft, as part of the second phase of the Chinese Lunar Exploration Programme. The first phase of the programme, Chang'e 1, was launched in 2007 with debris impacting the surface of the Moon in 2009

Number of China's trackable objects in orbit

Most space debris comes from break-up events caused by explosions and collisions. In the 1960s several spacecraft were made to intentionally self-destruct while others were destroyed through anti-satellite weapons tests

There are more than 4,500 satellites orbiting Earth which are catalogued along with some 14,000 old rocket parts and pieces of space junk

Top countries/agencies with the most space junk
Number of trackable objects in orbit (as of November 2018)

Since 1964

Since 1958

Since 1970

Since 1965

Since 1971

Since 1981

Since 1977

Since 1965

Since 1998

Since 1988

Since 1964

Since 1958

Since 1970

Since 1965

Since 1971

Since 1981

Since 1977

Since 1998

It is estimated that more than 500 break-ups have resulted in fragmentation. The two worst events resulting in the growth of space debris were the intentional destruction of a Chinese satellite, and the accidental collision of two satellites

On January 11, 2007, China tests an anti-satellite missile against the defunct Fengyun-IC weather satellite The Fengyun weather satellites are first deployed in the late 1980s. Fengyun-IC is launched on May 10, 1999, into a polar, sun-synchronous low Earth orbit

The destruction of Fengyun-IC creates an estimated 300,000 objects 1cm or larger – big enough to be fatal to a satellite mission. More than 3,000 pieces of debris are at least 10cm long – large enough to be tracked. The debris cloud generated is the largest ever recorded

The first accidental collision of two satellites occurs between America’s Iridium 33 and Russia’s Cosmos 2251, on February 10, 2009

Iridium 33 is a communications satellite launched into low Earth orbit by the US on September 14, 1997 Cosmos 2251 is a Russian communications satellite launched into low Earth orbit on June 16, 1993

The collision in 2009 adds more than 2,000 fragments to the catalogue of tracked objects



The trash situation in space is getting worse and risks making space off-limits for future generations, according to the European Space Agency's (ESA) chief space debris expert

When a piece of space junk is created, it will end up either slowing down to fall back toward Earth, burning up in the atmosphere or it will crash into another piece of space trash, producing more, smaller projectiles with orbits of their own

Number of trackable objects in orbit by category (year)
As of November 2018, space objects are categorised according to the launch date

The 2007 destruction of China’s Fengyun-IC, a satellite launched in 1999, adds over 3,000 fragments to the catalogue of tracked objects



1958: 3 objects

ALL YEARS

Potential dangers
A 5cm object is large enough to destroy a satellite or rocket body if the debris collides with the main body of the spacecraft

Equivalent TNT by debris size (kg)

Every space agency is proposing its own clean-up plan

History of China's space launches



There are four major space launch
bases in China
a. Jiuquan Satellite Launch Centre
Orbital launches: Low, medium and high Earth orbits
b. Taiyuan Satellite Launch Centre
Orbital launches: Sun synchronous and low Earth orbits
c. Xichang Satellite Launch Centre
Orbital launches: Geosynchronous orbit
d. Wenchang Satellite Launch Centre
Orbital launches: Geosynchronous and polar orbits

In January this year, a paper published by researchers at the Air Force Engineering University in China describes how space debris could be zapped into smaller, less-harmful pieces using space-based lasers. Some specialists are skeptical of China’s intentions, questioning if the technology is aimed at challenging Nasa’s dominance

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