Electrostatic Tractor for Near Earth Object Deflection
- Paper number
IAC-08.A3.I.5
- Author
Dr. Dario Izzo, European Space Agency (ESA), The Netherlands
- Coauthor
Ms. Naomi Murdoch, The Open University/ The Observatoire de la Côte d'Azur, France
- Coauthor
Dr. Claudio Bombardelli, Advanced Concepts Team, The Netherlands
- Coauthor
Dr. Alain Hilgers, European Space Agency (ESA), The Netherlands
- Coauthor
Mr. Ian Carnelli, European Space Agency (ESA), The Netherlands
- Coauthor
Dr. David Rodgers, The Netherlands
- Year
2008
- Abstract
There are many proposed concepts for deflection of a potentially hazardous asteroid. In the Gravity Tractor (GT) concept first introduced by Lu and Love [3] the spacecraft would gradually and controllably modify the asteroid trajectory by hovering alongside the asteroid, in static equilibrium, with its thrusters angled outwards preventing the exhaust plumes from impinging on the asteroid surface. McInnes [4] demonstrated that displaced, highly non-Keplerian (halo) orbits could, in certain circumstances, provide a more effective use of the gravitational coupling to modify asteroid orbits. The gravitational coupling between the asteroid and the spacecraft allows for this deflection technique, but it also puts a constraint the hovering altitude or of the Halo orbit and ultimately on the spacecraft mass.
This paper presents the Electrostatic Tractor (ET) as a new concept for asteroid deflection. The ET exploits the mutual electrostatic interaction between a charged asteroid and a charged spacecraft to slowly accelerate the asteroid. It is found that the artificial gravity effect produced by the electrostatic interaction can enhance the capabilities of gravity tractors and help to alleviate existing limitations of the GT concept.
A conductive body in space will become naturally charged primarily as a result of the ambient space plasma and solar extreme ultraviolet (EUV) [5]. It is known that electrostatic fields develop at the surface of resistive asteroids exposed directly to solar radiation and the solar wind [2]. Metal-rich M-type objects are almost certainly good conductors and the C-type asteroids may be reasonably good conductors even at typical asteroidal surface temperatures [1]. Satellite charging has been proposed for formation flying purposes [9], the charge being achieved by unbiasing the neutralizer of the ion engine on board [10] or by some other device. A very high bandwidth control has been proven to be possible introducing a minimal power requirement on board [9].
Using software developed by Thiebault et al [11] electric field from a charged asteroid immersed in a plasma environment is calculated and it is shown that the ET provides a considerable advantage over the conventional GT whilst having feasible power requirements to maintain the potential. The artificial electrostatic gravity effect on the restricted three body problem (Lagrangian points, Halo Orbits, Hovering equilibria) is also considered, and the resulting deflection efficiency is calculated using the asteroid deflection formula [7,8], which gives the displacement of the asteroid image on the encounter b-plane.
We apply our concept to two test cases with non-zero Earth impact probabilities: 9942 Apophis and 2004VD17 with respective impact dates of 2036 and 2102[6]. We find that the ET is able to achieve a fine gravity control upon the asteroid, ultimately controlling its own dynamic and allowing for a greater freedom in the design of the spacecraft hovering/halo orbit.
.4cm References .4cm [1] IP, W.-H., and Herbert, F., On the Asteroidal conductivities as inferred from meteorites, The Moon and Planets 28 (1983) 43-47
[2] Lee, P., Electrostatic Levitation of Fines on asteroids, Meteoritics, vol. 30, no. 5, page 535, 1995
[3] Lu, E.D., Love, S.G.,A Gravitational Tractor for Towing Asteroids, arXiv:astro-ph/0509595v1, 2005
[4] McInnes, Colin R., Near Earth Object Orbit Modification Using Gravitational Coupling, Journal of Guidance, Control, And Dynamics. Vol 30, No. 3, May-June 2007 p870-873.
[5] Purvis, C. K., Garret, H. B., Whittlesey, A. C. and Stevens, N.J., Design Guidelines for Assessing and Controlling Spacecraft Charging Effects, NASA Technical Paper 2361, 1984
[6] Schweickart, R., Chapman, C., Durda, D., Hut, P., Threat Mitigation: The Gravity Tractor, arXiv:physics/0608157v1, 2006
[7] Izzo D., Bourdoux A., Walker R., Ongaro F., Optimal Trajectories for the Impulsive Deflection of NEOs, Acta Astronautica, vol. 59, no. 1-5, pp. 294-300, April 2006.
[8] Izzo D., Optimization of Interplanetary Trajectories for Impulsive and Continuous Asteroid Deflection, Journal of Guidance Control and Dynamics, vol. 30, no. 2, pp.401-408, 2007.
[9] H. Schaub, G. G. Parker and L. B. King, “Challenges and Prospects of Coulomb Spacecraft Formations,” AAS John L. Junkins Astrodynamics Symposium, College Station, TX, May 23–24, 2003, Paper No. AAS-03-278.
[10] Pettazzi, L., Kruger, H., and Theil, S., Electrostatic Forces for Satellite Swarm Navigation and Reconfiguration, European Space Agency, the Advanced Concepts Team, Ariadna Final Report (05-4107a), 2006.
[11] Thiebault, B., Hilgers, A., Sasot, E., Laakso, H., Escoubet, P., Genot, V. and Forest, J., Potential barrier in the electrostatic sheath around a magnetospheric spacecraft, Journal of Geophysical Research, Vol. 109, A12207.
- Abstract document
- Manuscript document
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