Mission analysis and system design of a near-term and far-term pole-sitter mission

• Main Authors: Heiligers, J., Ceriotti, M., McInnes, C.R., Biggs, J.D.
• Format: Conference Object
• Language: unknown
• Published: 2012
• Subjects: Sitter; South Pole; South pole
• Online Access: http://eprints.gla.ac.uk/89732/; http://www.astrodynamics.org.pt/

This paper provides a detailed mission analysis and systems design of a near-term and far-term pole-sitter mission. The pole-sitter concept was previously in-troduced as a solution to the poor temporal resolution of polar observations from highly inclined, low Earth orbits and the poor high latitude coverage from geo-stationary orbit. It considers a spacecraft that is continuously above either the North or South Pole and, as such, can provide real-time, continuous and hemi-spherical coverage of the polar regions. Being on a non-Keplerian orbit, a con-tinuous thrust is required to maintain the pole-sitter position. For this, two dif-ferent propulsion strategies are proposed, which result in a near-term pole-sitter mission using solar electric propulsion (SEP) and a far-term pole-sitter mission where the SEP thruster is hybridized with a solar sail. For both propulsion strat-egies, minimum propellant pole-sitter orbits are designed. In order to maximize the spacecraft mass at the start of the operations phase of the mission, the trans-fer from Earth to the pole-sitter is designed and optimized assuming either a So-yuz or an Ariane 5 launch. The maximized mass upon injection into the pole-sitter orbit is subsequently used in a detailed mass budget analysis that will al-low for a trade-off between mission lifetime and payload mass capacity. Also, candidate payloads for a range of applications are investigated. Finally, transfers between north and south pole-sitter orbits are considered to overcome the limita-tions in observations due to the tilt of the polar axis that causes the Poles to be alternately situated in darkness. It will be shown that in some cases these trans-fers allow for propellant savings, enabling a further extension of the pole-sitter mission.