Space isn’t normally the place where you think to clean up your litter. A vast, open environment, uninhabitable by man and covering an unimaginable amount of area, outer space appears to be the one place where rubbish tends to be unimportant. Recent reports have surfaced detailing the importance of tracking space debris in order to ensure a safe orbital environment.
Computer generated images of objects in low Earth orbit, the region of space within 2000 km of the Earth’s surface. Approximately 95% of the objects are orbital debris, not functional satellites. http://www.nasa.gov/centers/wstf/laboratories/hypervelocity/mmod.html
Space object behavioral science includes the studies of all objects in space relative to the Earth’s orbit. These objects include comets, meteorites, artificial satellites, and rocket and satellite debris. The debris from rockets and satellites are glass, plastic, and metallic fragments which drift into the Earth’s orbit. Many pieces will burn up in Earth’s orbit while several will drift within one of the many layers of orbit. Approximately 22,000 objects are fully identified and tracked in space. However, scientists estimate another 300,000 to 500,000 man-made debris objects float in orbit untracked and unidentified.
In early March, the University of Arizona pulled several key researchers and defense software engineers to outline a plan of attack for the detection and tracking of space objects and debris hanging in Earth’s orbit. The key topics were discussions of solutions to track, identify, and map patterns of all objects, man-made and natural, within Earth’s orbit. The group proposed creating a unified space object behavior ontology to identify most, if not all, of the debris based on a multitude of measurements and data.
The goal of the ontology is to create a methodology for a system of object types, rotational and velocity measurements, and materials. The ontology gives trackers data indicative of an object’s spin, rotation, velocity, and predicted movement. Knowing when and where a trash fragment will be gives commercial satellite operators a chance to avoid a collision in space.
So why now? Why are key astrodynamicists and researchers worried about space debris if the actual coverage of space is so vast? The issue lies within the prevention of a catastrophic event in space and the tracking of international satellites for defense purposes.
STS-35 Space Shuttle window pit from orbital debris impact. http://www.nasa.gov/centers/wstf/laboratories/hypervelocity/mmod.html
Man-made debris from satellites and rockets poses a much greater danger than we normally would expect. Scrap metal and other trash particles can travel upwards to 10 km/s, approximately 10 times faster than the velocity of a sniper rifle bullet. The destructive potential of space debris poses a threat to all functional deployments in orbit. Communication satellites, the International Space Station, and every other man-made object launched into space is vulnerable to a catastrophic collision from debris.
Space object debris is not limited to junk created from rocket boosters. All launched satellites generate trash over time as each satellite has a limited life expectancy. Adhesives holding solar panels will eventually wear out, sending each panel off into separate vectors. Space weathering forces will eventually cause shards of debris to leaf off of satellites, causing more particles to separate from the object. Estimates for the life expectancy for a single satellite may range from 8 to 10 years, but the unpredictable nature of space leaves uncertainty for the actual expiration date. Satellite protocol requires the objects need to be piloted into the Earth’s atmosphere to burn up before more debris scatters.
NASA, the U.S. Department of Defense, and various international organizations have undertaken several initiatives to track the behavior of every single unidentifiable object hanging in Earth’s orbit. The Space Act of 2015 requires reporting by the U.S. government to commercial satellite owners about the nature and danger of debris items. With more and more of them launching low-cost CubeSats as well as more countries investing in launching their own satellites, it is imperative to institute a reliable method to track and identify each satellite and the debris which may pose a danger to them.
The question lingers about whether or not an ontology would be the solution to this crisis. While an ontology would allow scientists and researchers to pool their data, the overarching hurdle is the open sharing of that data. International policies with Russia and China would leave a lot of the data closed off or heavily curated to the point of uselessness due to defense policy. Additionally, different standards and techniques with regards to measuring each object vary greatly from country, institution, and corporations. The answer will always be “we need more data.”
The first step for those willing to tackle the issue of space debris is to figure out a specific use case for an ontology in which the contributors build out the components which will solve the issue, test, and attempt to replicate data. While a lack of information or questionable data integrity could lead to hurdles down the road, it would give many software developers a starting point for tackling these issues.
Jack Bruce, Senior Taxonomist