Threat of being caged on Earth forever

It appears that the more orderly we try to make our lives, more disordered we turn our surroundings. In pursuit of development and comfort, we have littered our systems so much, that it has become a swirling vortex of entropy. We have littered the lands, oceans, rivers and even Space, From harmless nuts, screwdrivers, gloves, cameras, garbage bags, tools and paint flecks to solid fuel, obsolete satellites and nuclear reactor cores, dead spacecrafts, weapons, boosters.

This is becoming an acute problem as we launch more and more hardware into orbit every year, including thousands of Starlink satellites. Since the first satellite that went into the orbit in 1957, Sputnik I, we've launched 8000+ satellites into different orbits.

Space debris is defined as all non-functional, human-made objects, in Earth orbit.

Orbital debris was initially referred to the natural debris found in the Solar System i.e. asteroids, comets, and meteors. In 1979, NASA launched Orbital Debris Program at Johnson Space Centre, to measure and locate debris in Space, and develop solutions to counter it. Thereafter, the term also refers to stuff mentioned above.

Because stuff in orbit travel at very high speeds (8+ km/sec) to maintain their altitude, even a paint fleck can be as dangerous as a bullet! Rising junk count lead to rise in the probability for catastrophic collisions.

As the debris population grows, more collisions will occur.

• There is 6,000 tonnes of debris.
• At present, there are more than 20,000 pieces of junk larger than a 5 cm.
• 34,000+ pieces larger than 10 cm.
• There are 500,000+ pieces of size near 1 cm.
• Over 128 million pieces of debris smaller than 1 cm.
• There are even more millions of pieces so small

These particles cannot be tracked and They travel at speeds up to 28,000 kmph. Density of Space Debris also depends on the altitude of orbits. Following table is a guide for different orbits with their altitudes & revolution time:

Collisions with debris have become a hazard to spacecraft; they cause damage akin to sandblasting, especially to solar panels and optics like telescopes. In fact any debris larger than 0.1 mm has the capability of penetrating a space suit.

There have been several accidents occured due to Orbital debris

• In 1996, a French satellite was hit by debris from a French rocket that had exploded a decade earlier.
• In Feb, 2009, a defunct Russian satellite collided with U.S. Iridium commercial satellite, that created 2,000+ pieces of debris.
• In 2007, China tested its Anti-Satellite missiles to destroy an old weather satellite added more than 3,000 pieces to the debris problem.

Apart from hazards to our Space Assets, Space Junk is also a threat for technologies such as Internet, television, GPS and weather related services that rely on satellites, so an event of Kessler Syndrome, although very unlikely, can destroy our satellites, Setting our civilization a hundred years back.

Kessler syndrome is a situation when the density of objects in the LEO grows so high that collisions between two objects could cause a massive cascade, where those collisions generate more space debris, which, in turn, increases the likelihood of further collisions. The distribution of debris in orbit could render space activities and the use of?satellites?in specific orbital ranges difficult for many generations.

Ralph Dinsley, founder and executive director of Northern Space and Security LTD has warned that there is so much space junk in low Earth orbit that humanity could become trapped, he believes that we are approaching a point where it could be too late.

“The space junk problem has been getting worse every year,” Ben Greene, head of Australia’s Space Environment Research Centre in Canberra, told AFP. “We’re losing three or four satellites a year now to space debris collision. We’re very close, NASA estimates, of within five to 10 years of losing everything”

The worst case scenario is horrifying, as a debris field of hundreds of millions of pieces, many too small to track, moving at high speeds could create a deadly barrier around earth that may be too dangerous for us to cross. Our dreams of creating moon bases, colonizing Mars or space travel can be set back decades. If our space infrastructure is destroyed, some of our technology, on which we rely daily, can be sent back to the 1950s.

Research agencies are finding measures through which Orbital debris could be decreased meanwhile tracking the objects with the help of Radar, Radio waves, Space telescopes and Optical detectors such as LIDAR.

The International Space Station has debris shields deployed around the crewed modules. These shields are composed of two metal sheets, separated by about 10 cm. The outer bumper shield exploits the impact energy to shatter the debris object, such that the inner back wall can withstand the resulting spray of smaller-sized fragments.Between the walls, fabric with the same functionality as in bullet-proof vests is deployed. This design enables the shield to defeat debris objects up to 1 cm in size.

Debris avoidance maneuvers are planned when the probability of collision reaches its limits in the space shuttle and space station flight rules. If the probability of collision is greater than 1 in 100,000, a maneuver will be conducted if it will not result in significant impact to mission objectives. If it is greater than 1 in 10,000, a maneuver will be conducted unless it will result in additional risk to the crew. Several collision avoidance maneuvers with the shuttle and the station have been conducted during the past 10 years.

The Space Junk removal systems are classified into two categories:

1. Contact methods:

• Electrodynamic tethers: The tether would latch onto the orbiting hunk of trash, and the operating spacecraft would then drag the debris down into atmosphere.
• Solar Sails: They are a method of spacecraft propulsion using radiation pressure exerted by sunlight on large mirrors.
• Robotic arms: Ultra-fast robotic arms that can catch Space debris and push them towards Earth's orbit.
• Space nets: These are satellites that 'fishes' or collects the debris and is later disposed off into graveyard orbit.

2. Contactless methods: Lasers and Ion beams to slow down medium sized (between 1 cm and 10 cm diameter) objects, forcing them to rapidly descend and burn up in the atmosphere.