@article{french_mazzoleni_2009, title={Asteroid Diversion Using a Long Tether and Ballast}, volume={46}, ISSN={["0022-4650"]}, DOI={10.2514/1.40828}, abstractNote={The threat of an asteroid or comet impacting the Earth has been receiving more attention in recent years, due in part to the discovery of the Apophis asteroid, which was at one time projected to have a significant probability of impacting the Earth in the year 2029. Although a later analysis of the Apophis trajectory precluded this impact, the threat has brought a lot of attention to the dangers posed by asteroids. Many ideas have been put forward for mitigating such threats. This paper presents one such technique: the attachment of a long tether and ballast mass to change the orbit of an Earth-threatening asteroid or comet. Specifically, for this paper, a parametric study was conducted to determine to what degree the trajectory of an asteroid or comet could be altered by attaching a tether and ballast for various values of orbital semimajor axis and eccentricity and for various tether lengths and ballast mass sizes. The results show that a long tether and ballast mass could be effective for such a diversion. It was found that the technique was most effective using longer tethers and larger ballast masses on asteroids or comets with smaller, more eccentric, orbits.}, number={3}, journal={JOURNAL OF SPACECRAFT AND ROCKETS}, author={French, David B. and Mazzoleni, Andre P.}, year={2009}, pages={645–661} }
 @article{french_mazzoleni_2009, title={Near-Earth object threat mitigation using a tethered ballast mass}, volume={22}, DOI={10.1061/(ASCE)0893-1321(2009)22:4(460)}, abstractNote={The effects of the collision of a near-earth object (NEO) with the Earth could be catastrophic on a local, regional, or global scale depending on the size of the NEO. Therefore, there is considerable interest in determining ways to mitigate the threat posed by these objects. This paper presents a method using the attachment of a tether and ballast mass to alter the trajectory of a NEO on an Earth-intersecting orbit so that it avoids hitting the Earth. Furthermore, a parametric study of such a system is conducted over a wide range of parameters that describe the orbit and the system itself. For each set of parameters, a resulting “miss distance” due to the attachment of the tether and ballast mass is calculated. The results demonstrate that such a system could be used to protect the Earth from Earth-intersecting NEOs.}, number={4}, journal={Journal of Aerospace Engineering}, author={French, D. B. and Mazzoleni, A. P.}, year={2009}, pages={460–465} }
 @article{french_mazzoleni_2009, title={Parametric study of the diversion of a near Earth object on an Earth intersecting trajectory}, volume={65}, ISSN={["1879-2030"]}, DOI={10.1016/j.actaastro.2009.04.023}, abstractNote={To date, NASA's “Near Earth Object Program” has discovered over 5500 comets and asteroids on trajectories that bring them within “the neighborhood” of Earth's orbit. Nearly 1000 of these objects are classified as “potentially hazardous,” passing within 0.05 astronomical units of Earth's orbit. Discovery rates of such threatening bodies increase each year. Given this multitude of threats, in addition to evidence that the planet has absorbed many impacts over its history, it is reasonable to assume that another object will strike the Earth at some point in the future. Consequently, researchers have studied and proposed several mitigation techniques for such an occurrence. This study seeks to determine how effectively the attachment of a tether and ballast mass would divert the trajectory of such threatening objects. Specifically, the study analyzes the effects over time of such a system on objects of varying orbital semimajor axis and eccentricity, using various tether lengths and ballast masses. It was determined that the technique is most effective for NEOs with high eccentricity and small semimajor axis, and that system performance increases as tether length and ballast mass increase.}, number={11-12}, journal={ACTA ASTRONAUTICA}, author={French, David B. and Mazzoleni, Andre P.}, year={2009}, month={Dec}, pages={1698–1705} }