Among the developing challenges countries with the desire to protect their infrastructure in space is the presence of debris in orbit. The magnitude of the challenge has heightened by 50 % in 2007. This was the same period when the Chinese government intentionally destroyed one of its satellites. Two years later, Iridium and the retired Russian satellite collided leaving some of its parts in space. Space debris is, therefore, a universal problem that requires immediate solution. The study argues that space debris hugely affects space shuttles and spacecraft. The study focuses on the reason why space debris is a problem, how to track the debris and possible solutions in removing the debris. Numerous scientific and technical terminologies have been applied in the study. These include space debris, Kessler syndrome, Debris avoidance maneuvers, Soyuz spacecraft, LEO, and Space Infrastructure Servicing (SIS). Space Debris refers to the wastes and collection of the dysfunctional fabricated and naturally occurring objects in space. Kessler syndrome is a runaway chain reaction of collisions that exponentially increases the debris in space. Debris avoidance maneuvers are planned strategies for protected transmission of data within the space by minimizing events of collusion between the debris and the spacecraft. Soyuz spacecraft is a device employed as a boat for crewmembers during emergency periods and used to transport human beings to and from another station in case there is no sufficient time to warrant maneuver of the box. SIS is a commercially developed vehicle used for capturing and returning debris to a central station. The device pushes dead satellites to graveyard orbits for them to burn up in the atmosphere. LEO refers to the low earth orbit where debris easily decays thereby causing minimal effects to other space devices.
Even though the outer space is assumed desolate and empty, the region surrounding the earth possesses millions of fabricated wasters that posses potential hazards to the operational devices in space. Space debris refers to the collection of the dysfunctional manufactured objects in space, inclusive of the disintegration from the debris itself (Anselmo & Pardini, 2000). These wastes come from dead spacecraft, lost equipment, boosters, and weapons. By 2013, at least 200,000 amount of debris were present in the space, with at least 1,500 operational satellites in space. The study focuses on the reason why space debris is a problem, how to track the debris and possible solutions in removing the debris. The study further informs whether the problem will worsen as more countries gain access to space. Major technological and scientific concepts related to removal of space debris have been discussed overwhelmingly in the study.
Features of the space debris
At least 150 million wastes are smaller than 1 cm, with at least 650,000 pieces of the debris ranging 1-10 cm (Kramer, 2016). Large debris is defined as 10 cm larger with a technical measurement cutoff approximated as three millimeters. Millions of wastes that are smaller than a third of an inch travel at 4 miles per second can punch a 550-pound object traveling at 60 miles per hour. Such an impact has the potential of damaging critical components like the pressurized items, tethers, and creates new pieces of threatening debris (Redd, 2013). 1,500 objects and 5,000 tones in weight account for at least 97% of the 1,900 tons of the wastes in the Low Earth Orbit (LEO). The universal orbits in Low Earth Orbit (LEO), which keeps the spacecraft in specific rings, are very few. The Sun-synchronous orbits are the closest, polar, and keep a specific angle linking the sun and the orbital plane. Since orbits are modified by perturbations, the Kessler syndrome applies within the LEO region and impacts up to 16 km/s if it is a head-on collision. The Kessler syndrome can cross over to other orbits and create a cascade effect, reducing the LEO to impracticality. In higher altitudes, air drags are less considerable and hence orbital decay takes longer to effect (NASA, 2013). For wastes to decay, it is necessary that they encounter some force such as insignificant atmospheric drag, earth’s gravitational perturbations, and solar wind and radiation pressure to drag them to the lower altitudes.
Space debris as a problem
At least five million pieces of debris are traced within the earth’s space. These particles travel at estimated speeds of 17,500 miles per hour, a sufficient speed for damaging a spacecraft or satellite. This is especially dangerous to space shuttles and spacecraft carrying human beings. Natural (meteoroid) and artificial (manufactured) particles from space debris within the orbit of the sun and of the earth, respectively. Orbital debris encompasses nonfunctional spacecraft, discarded vehicle stages, mission-related, and fragmentation debris. More than 20,000 of these pieces are larger than a soft ball while at least 500,000 pieces are the size of a marble. The great number of this debris makes it difficult for scientists to follow, a fact that poses huge risks to space missions.
Evidence of Space Debris
Irrespective of the efforts to manage risks, spacecraft collisions have taken place in the past (NASA, 2013). In 1993, a European Space Agency’s telecom satellite was struck by a meteoroid and moved to the graveyard orbit. Remains of an Arianne-1 H-10 booster that exploded in 1996 hit a French microsatellite in Sun-synchronous Leo. In 2006, a Russian communication satellite was struck by unidentified item and rendered inoperable. A runaway chain reaction of collisions that exponentially increases the debris also referred to as the Kessler Syndrome, is assumed to proceed beyond the critical density, thereby affecting the valuable polar-orbiting bands, increasing the cost of protection for spacecraft mission, and destroying live satellites.
Kramer (2016), reports on a collision between some space debris and a Copernicus Sentinel-1A spacecraft in space that resulted in a minute and sudden power loss from one of the solar panels on August 23. Turning a couple of cameras towards the direction of the collision, scientists in this space found evidence of a 16-inch collision between a piece of dust and solar panel. The particles seem to speed at thousands of miles per hour, harming active assets in space. This recent collision offers sufficient proof of the presence of spent rocket bodies that easily damage active satellites in space. One photo from the International Space Stations depicts a chip that had been removed from a space station’s window and a bullet hole on the solar panels (Kramer, 2016).
Tracking space debris
One approach employed by NASA and DOD is to share the responsibility of characterizing the environment of the satellites. Through the space surveillance network, discrete objects of around five centimeters are tracked in the LEO and in one-meter geosynchronous orbit. Approximately 15,000 cataloged objects are in the orbit with the total tracked number of these objects to exceed 21,000. NASA statistically applies special ground-based sensors and inspections of surfaces of returned satellite to determine the population of the objects that are within four inches wide (NASA, 2013).
To evaluate whether the threat of close movements with the debris is sufficient to warrant evasive action, NASA sets safety measures to ensure that the crew is the shuttle is safe (NASA, 2013). Among the guidelines, include an imaginary box that has a mile deep by 30 miles across and 30 miles long with a vehicle at its center. If the debris is to pass close to the vehicle and thus affect the tracking data, mission control centers develop a prudent course of action. When these encounters have been determined in advance, a debris avoidance maneuver is done to keep the debris away from the box and isolate the spaceships from the station (NASA, 2013). Debris avoidance maneuvers are planned approaches of safe transmission of data within the space by minimizing events of collusion between the debris and the spacecraft. Debris avoidance Maneuvers are applied in the event of the likelihood of collision that is above 1 in 100,000 and if the effect will not significantly affect mission objectives, and consequence in more risks to the crew. Debris avoidance Maneuvers occur within several hours before the period set for the conjunction, executed within a matter of hours, and require approximately 30 hours of planning due to the necessity of applying Russian thrusters at the station or the application of the propulsion systems of a Russian or an American spacecraft. This collision avoidance has been applied for the earth observation system satellites and the Data Relay System geosynchronous orbit. The Soyuz spacecraft is employed further to transport human beings to and from another station in case there is no sufficient time to warrant maneuver of the box. The Soyuz spacecraft is employed therefore as a boat for crewmembers during emergency periods.
Possible solutions in removing space debris
Cleaning the present space debris poses a huge challenge due to the size of the objects and the related financial costs. Among the approaches presently applied in preventing a collision is to keep track of the debris. The U.S. and the Russian military are capable of observing debris as big as 10 cm through radars before a launch (Kramer, 2016), Space shuttles are capable of changing their orbits if larger objects approach their orbits. Nevertheless, all devices sent to space faces potential collisions with smaller and untraceable objects. Satellites and spacecraft are usually shielded to guide vital components. Numerous space organizations are presently working to reduce the wastes in the earth’s orbit by executing enhanced designs. One approach Russia, and Japan, among other nations have agreed on is to minimize potential effectors in orbit. Researchers are in the process of unveiling path-shifting push using a laser. Even though protected space activities occur at altitudes lower than 800 -1,500 km, a Kessler syndrome collision would rain down to lower altitudes and the decay time scale would make the environment too hostile for future space use (Redd, 2013).
Impact of space debris in the future
The unprotected spacecraft, debris account for 50% of the general threats experienced while in space (NASA, 2013). Objects re-entering the atmosphere affects the ozone layer by sending a shock wave to the stratosphere, which produces nitric oxide (Tate, 2013). During re-entry, spacecraft and rocket motors melt away the metal alloys and composite materials after intense heating, resulting in depletion of the ozone layer. Tate (2013) highlights that a collision even with a tiny element is disastrous as it guides to a catastrophic disintegration of the spacecraft and rocket bodies. The Kessler syndrome is likely to result to impassable orbital space, as more disintegration will take place. The ultimate effect is the runaway domino effect in the LEO, which will be too hazardous for human and satellite movement. With the increase of the debris in space, scientists are called to invent advanced detectors for observation. Presently, radar and optical detectors like lidar are used for tracking the wastes of more than 10 cm in size.
Even though selected orbital cannot protect lanes from wastes, future ITU requirements oblige satellites to move to the graveyard orbit towards the end of their lives (NASA, 2013). These measures have been stipulated categorically so that the lifetime of the wastes can be accurately calculated. Satellites with adequate propellants at times make direct and controlled de-orbiting to reduce atmospheric re-entry period of the debris. The Space Infrastructure servicing (SIS) is a commercially developed vehicle used for capturing and returning debris to a central station (NASA, 2013). The device pushes dead satellites to graveyard orbits for them to burn up in the atmosphere. The SIS devices differentiate the potential between the debris and itself and thrust itself together with the debris to a safer orbit. Variations of the device temporarily capture the debris and attach them to smaller de-orbit satellite for removal. The European Space Agency is presently on a mission to remove large space debris that is heavier than four tones from the orbit. The mission is expected to apply numerous devices including a net, a harpoon, and a collection of a robot arm and clamping mechanism.
One challenge the world is presently facing is to protect infrastructure in space from the threat of space debris whose magnitude has heightened by 50 % in 2007. Space debris is the collection of dysfunctional fabricated objects in space. These particles approximately travel at speeds of 17,500 miles per hour, which is sufficient for damaging a spacecraft especially those carrying human beings. Although numerous strategies are being actualized to reduce these wastes from space, it is still challenging to clear the space due to the size of the objects and the related financial costs.
Anselmo, L. & Pardini, C. (2000). Collision Risk Mitigation in Geostationary Orbit. Space
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Kramer, M. (2016). A European Satellite got hit by some kind of Space Debris. Mashable.
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Redd, T. N. (2013). Space Junk: Tracking & Removing orbital debris. Space.com.
Tate, K. (2013). Space Junk Explained: How Orbital Debris threatens future of spaceflight
Definition of Terms
The sun and space weather
- Space refers to any position within outside of the atmosphere of the earth
- Space debris– the collection of the dysfunctional man-made objects in space, inclusive of the disintegration from the debris itself
- Meteoroid is a minute solid extraterrestrial body that forms part of the space debris and possible of hitting earth’s atmosphere.
Propulsion and orbital mechanics
- Debris voidance maneuver– The process of moving a satellite stations slightly to avoid collision with the space debris
- SIS is a commercially developed vehicle used for capturing and returning debris to a central station.
- Soyuz spacecraft is a device employed as a boat for crewmembers during emergency periods, and used to transport human beings to and from another station in case there is no sufficient time to warrant maneuver of the box.
- Kessler syndrome is a runaway chain reaction of collisions that exponentially increases the debris in space.
- Sun-synchronous orbits are the closest and polar orbits with specific angle that links the sun and the orbital plane
- Low Earth Orbit (LEO) is the low earth orbit which keeps the spacecraft in specific rings and bears at least 500,000 objects, which account for 97% of the 1,900 tons