Low-Thrust Mission Design to Impact Asteroid 2001-TW229
- Paper number
IAC-06-C1.4.09
- Author
Mr. Juan L. Cano, DEIMOS Space S.L., Spain
- Coauthor
Mr. Miguel Bello Mora, DEIMOS Space S.L., Spain
- Year
2006
- Abstract
Hitting an asteroid in interplanetary space to analyse the achievable deflection in the asteroid orbit is currently a very hot topic in Astronautics and Global Security. Humankind has to demonstrate in the years to come the capability to lower the threat that some Near Earth Asteroids (NEA) could pose on the Earth in the short and medium term. Recently, the European Space Agency (ESA) has closed the 1st ACT Global Trajectory Optimisation Competition (ACT standing for Advanced Concepts Team at ESA). At this first Competition, ESA proposed to the Trajectory Optimisation Community to address the optimisation of the trajectory to a specific NEA (2001-TW229) such that the imparted change in the linear momentum was maximum. The probe would make use of a low-thrust propulsion system departing from Earth with a specified escape velocity and having the possibility to swingby a number of planets (including the giant planets). Maximum travel time was posed at 30 years. The proposed problem was envisioned to characterise the tools and the procedures available to optimise complex trajectories with state-of-the-art design conditions. Up to 17 teams worldwide participated in the Competition proposing a varied number of solutions. The solution proposed by DEIMOS Space was evaluated in the second position almost achieving the same figure of merit than the winning team and with a large difference with respect to the rest of the teams. The approach proposed by DEIMOS to the solution of the problem was based on a three-step strategy: - Systematic search of ballistic options with powered swingbys - Selection of best suited solutions under a number of criteria - Refinement of the best solutions by means of a local parameters optimiser The proposed thrust modulus is was fact quite low, broadening and flattening the solution space. The thrust level only allowed to faintly interacting on the trajectory definition, thus having to largely rely on the use of massive bodies to achieve large changes in velocity and thus achieve the mission goal. The proposed cost function suggested that the best options would be those that allowed encountering the asteroid in opposed orbit to the S/C. For the spacecraft to reach a retrograde orbit, swingbys at the giant planets, Jupiter and Saturn were required. As a result of the first step a large number of feasible ballistic trajectories were found. The following combinations of planetary swingbys were analysed: EVEMEJSA, EVEVEVEJSA, and EVVEEVVEVEJSA (E-Earth, V-Venus, J-Jupiter, S-Saturn and A for the Asteroid). About 47,000 solutions with a cost function above 1600000 kgxkm2/s2 were identified by means of a scanning procedure. The largest achievable cost functions occur for travel times in the order of 28.5 years for the families of solutions tested. In the second step the most promising option was selected based on some criteria to minimise the impact of substituting the high-thrust manoeuvres by low-thrust manoeuvres. The final step involved the use of a local low-thrust optimiser to arrive to the proper final solution based on the use of the selected engine. The best cost function was obtained at 1819872 kgxkm2/s2 for a mission lasting for 28.331 years and with a structure EVVEEVVEVEJSJA.
- Abstract document
- Manuscript document
IAC-06-C1.4.09.pdf (🔒 authorized access only).
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