GALCIT Colloquium

Historical practice of abandoning satellites at the end of their lifetime has left 8,500 tones of space waste in Low Earth Orbit. In the future, this practice must change. Increasingly, space debris poses a risk for spacecraft. Hundreds of old satellites and thousands of pieces of space junk orbit Earth. Such debris collide, which in turn increases the amount of debris, as pieces of old satellites break of when hit by pieces of other retired spacecraft. Indeed, without a change of practice and the establishment of effective systems for safe de-orbiting of spacecraft at the end of their lifetime, it is estimated that the number of debris particles will grow with a growth rate in the order of 5 percent per year a percentage which would raise over time as the number of possible collisions increase.

Satellite Deorbiting requires multiple technologies to be used for different size of debris. This talk will present various technologies developed to be used for debris mitigation: (i) electric propulsion thrusters developed for active spacecraft in LEO and GEO which can be used for debris removal (ii) deployable structures/drag augmentation systems which can be used to lower the altitude of spacecraft/debris in LEO and allow tem to safely burn up in the earth s atmosphere.

Specific emphasis in this talk will be given to two nanosatellite demonstration missions, in development, called Cubesail and DEORBITSAIL.

The DEORBITSAIL project addresses this challenge, as it is set to develop a novel low cost low risk de-orbiting device for smaller spacecraft with a mass less than 500 kg that circulate Earth in Low Earth Orbit less than 900 km above us. DEORBITSAIL proposes to develop a 25 square metre Solar Sail, which would weight no more than 3 kg. Upon the end of its lifetime, the retired spacecraft would deploy this sail. Within 25 years, drag will drive the spacecraft downwards, taking the spacecraft home into Earth's atmosphere, where it would burn off safely. The 25 year de-orbiting period adheres to established recommendations by the European Space Agency (ESA) and by the UN. DEORBITSAIL has the potential to reduce future debris by 70 percent. DEORBITSAIL is a fully funded space mission, sponsored by the EU FP7 program to be launched in 2014 based on the Cubesail drag/sail concept to be launched in 2012.