Orbital Debris

What is it?

Space debris includes man-made and natural orbiting or incidental objects that typically lack navigational control. 

While we may be accustomed during our travels on our Nation’s highways to observe seemingly innocuous objects lying in highway culverts across America such broken hubcaps, fenders, tires and other vehicle parts, as well as garbage, stones, animals, fallen branches and the like,  these can be relatively harmless in this earthly environment for vehicle travel at normal travel speeds. In space however, the relative velocities between a vehicle and incidental debris is much higher and poses much greater danger if collision occurs. 

The main issue with orbital debris is that it moves extremely fast. In low Earth orbit (altitudes lower than 2,000 km), the average impact velocity is greater than 20,000 mph as a result even small, lightweight debris can have significant and varied consequences. NASA has often had to replace windows and other parts of space assets due to damage by small particles upon return to earth. Damage to persistent orbiting satellites or vessels would be much more difficult to repair in situ. Punctured vessels and spacesuits pose imminent dangers and larger energy collisions can have catastrophic effect.

A Growing Problem

 

During the nascence of the world’s space program, early spacecraft faced little threat of collision with orbiting man-made objects. With the burgeoning interest in space from around the globe, nations and private parties are increasing the material that is placed in orbit.

Orbital debris ranges in size from microscopic particles to large systems like rocket bodies that can be as tall as urban office buildings.  Considering the fact that something as small and inauspicious as a screw can damage spacecraft window, one can only imagine the amount of damage caused by large systems or rocket bodies running head on into an NRO satellite at some 20,000 mph.  This type of collision would create major issues back on Earth threatening national security and way of life.

While some objects will de-orbit, either through human intervention, or natural decay, a major contributor to this dilemma has been object break up. To date more than 200 breakups and 60 events in which debris was expelled from an orbiting object has occurred. Many more will occur beyond the writing of this narrative. Breakups can result from explosions to collisions to detonations to failure events. Causes of approximately 22% of observed breakups are unknown.

Two major recent events have significantly accelerated the growth of orbital debris.  Years ago, In 2009, a US Iridium 33 Satellite collided with a defunct Russian Kosmos 2252 satellite, creating over 2,000 tracked objects and many more untraced objects.  In 2007, the Chinese deliberately destroyed the FY-1C satellite in a test of an anti-satellite weapon, resulting in more than 3,000 tracked and many more untraced objects.

A present solution is to use ground tracking systems, wherein earth-based tracking systems such as ground stations which use mechanisms such as radar, lidar, signal Doppler, laser reflectors and other means to measure the position of an object and to maintain other data relevant to its orbital elements, which can be compiled to create an ephemeris database.

As of January 2019, more than 128 million pieces of debris smaller than 1 cm (0.4 in), about 900,000 pieces of debris 1-10 cm, and around 34,000 of pieces larger than 10 cm were estimated to be in orbit around the Earth.[1]

An even greater challenge exists in High Earth Orbit. At distances at or above geocentric orbits above the altitude of geosynchronous orbit 35, 786 km (22,240 miles). It is not possible to track smaller objects with accuracy (<1m) and difficult to make timely adjustments to existing spacecraft for collision avoidance.

GuardianSat™  provides solutions to these challenges.

[1] https://en.wikipedia.org/wiki/Space_debris