Near-Earth Object (NEO) Analysis of Transponder Tracking and Gravity Tractor Performance.
A study, requested and funded by the B612 Foundation, was
carried out by JPL scientists to detemine the feasibility of using a
gravity tractor concept for use in NEO impact mitigation and to build
credibility for the concept.
Using a hypothetical Earth impacting asteroid, simulations and
analyses were carried out; this report
presents the analysis results arising from an investigation into the:
- facility with which a spacecraft can be safely maintained in
close proximity to an irregularly shaped,
rotating asteroid (even a very simple control law allows
proximity spacecraft operations).
- rapidity with which optical navigation and ground-based
spacecraft radio tracking can be used to
precisely determine the asteroid's current and future
trajectories (only a few days/weeks of tracking
- viability of using an impacting spacecraft to provide enough
of a velocity change (deflection) to avert
an Earth collision several years in the future (this is a
viable primary deflection concept for the most
common hazardous asteroids).
- density and sizes of so-called "keyholes" near the Earth. At
an Earth close approach, a keyhole
passage by an asteroid would ensure a subsequent Earth
collision (a few % of deflected impactors
may also require trajectory trimming to avoid a keyhole).
- utility of a gravity tractor in preventing the asteroid from
entering one of these keyholes should the
primary deflection attempt inadvertently push the NEO into it
(a gravity tractor is a viable concept for
trajectory trimming to avoid most keyholes).
This work, requested and funded by the B612 Foundation, was
carried out by JPL scientists and
engineers in the Guidance, Navigation and Control Section (343):
D.K. Yeomans, S. Bhaskaran, S.B. Broschart, S.R. Chesley, P.W. Chodas,
M.A. Jones, and T.H. Sweetser.
The complete report is available here (Word Document - 4.4 MB)