Picture of boy being examining by doctor at a tuberculosis sanatorium

Understanding our future through Open Access research about our past...

Strathprints makes available scholarly Open Access content by researchers in the Centre for the Social History of Health & Healthcare (CSHHH), based within the School of Humanities, and considered Scotland's leading centre for the history of health and medicine.

Research at CSHHH explores the modern world since 1800 in locations as diverse as the UK, Asia, Africa, North America, and Europe. Areas of specialism include contraception and sexuality; family health and medical services; occupational health and medicine; disability; the history of psychiatry; conflict and warfare; and, drugs, pharmaceuticals and intoxicants.

Explore the Open Access research of the Centre for the Social History of Health and Healthcare. Or explore all of Strathclyde's Open Access research...

Image: Heart of England NHS Foundation Trust. Wellcome Collection - CC-BY.

Extension of highly elliptical Earth orbits using continuous low-thrust propulsion

Anderson, Pamela and Macdonald, Malcolm (2013) Extension of highly elliptical Earth orbits using continuous low-thrust propulsion. Journal of Guidance, Control and Dynamics, 36 (1). pp. 282-292. ISSN 1533-3884

[img] PDF

Download (1MB)


The extension of highly elliptical orbits, with free selection of orbit period, using low thrust propulsion is investigated. These newly proposed orbits, termed Taranis orbits, are enabled by existing low-thrust propulsion technology, offering a radically new set of tools for mission design and facilitating new, novel Earth Observation science. One particular example considered herein, using general and special perturbation techniques, is the application of continuous low-thrust to alter the ‘critical inclination’ of an orbit from the natural values of 63.4deg or 116.6deg, to any inclination required to optimally fulfill the mission goals. This continuous acceleration is used to compensate for the drift in argument of perigee caused by Earth’s gravitational field. Pseudo-spectral optimization techniques are applied to the 90deg inclination Taranis orbit, generating fuel optimal low-thrust control profiles, with a fuel saving of ~ 4% from general perturbation results. This orbit provides an alternative solution for high latitude imaging from distances equivalent to geostationary orbits. Analysis shows that the orbit enables continuous, high elevation visibility of frigid and neighboring temperate regions using only three spacecraft, whereas a Molniya orbit would require in excess of fifteen spacecraft, thus enabling high quality imaging which would otherwise be prohibited using conventional orbits. Order of magnitude mission lifetimes for a range of mass fractions and specific impulses are also determined. Finally, a Strawman mass budget is developed, where the mission lifetimes for spacecraft with initial mass of 1000kg, 1500kg, and 2500kg, are found to be limited to 4.3 years, 6 years and 7.4 years respectively.