What are Orbital Debris?
Orbital Debris or “Space Junk” is any human made object that no longer serves function out in earth’s orbit. This debris can harm the environment by releasing harmful chemicals into the atmosphere. They can also potentially damage other working satellites and pose danger to future space missions as it builds up. Unfortunately these orbital debris can last up to 1,000 years or more making it a difficult problem to solve. However, many companies realize this problem and are tracking orbital debris to avoid it.
LEGEND (NASA’s Evolutionary Model)
LEGEND is a sophisticated computer model that helps NASA study and predict the behavior of space debris around Earth. It can simulate both the past and future populations of debris. The main program and subroutines of LEGEND are written in standard FORTRAN 90 language, a computer language used in science and engineering, while additional analysis tools are written in MATLAB as well. The historical part of the model recreates known debris from past missions, including rockets, spacecraft, and other fragments.
The future projection part of the model uses a clever algorithm to estimate how debris will break up and grow over time. It uses a special model to estimate the chances of objects colliding in different parts of space. This model considers the real positions and movements of objects in three-dimensional space, without making assumptions about their orbits. LEGEND looks ahead for 200 years, but because there are many uncertainties, like future space missions and accidents, the program needs to run many simulations (over 100) to get reliable results.