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Iman Alizadeh University of California, Irvine. Reducing the Risk of Orbit Transfer in Low-thrust Missions. Image from http://dawn.jpl.nasa.gov/multimedia/images/vestaorbit_300.jpg. Motivation. Designing Space missions with low-cost. Low-thrust propulsion technology are very efficient.

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iman alizadeh university of california irvine
Iman Alizadeh

University of California, Irvine

Reducing the Riskof Orbit Transfer in Low-thrust Missions

Image from http://dawn.jpl.nasa.gov/multimedia/images/vestaorbit_300.jpg

motivation
Motivation
  • Designing Space missions with low-cost.
    • Low-thrust propulsion technology are very efficient

Image Credit: NASA/JPL

Image Credit: NASA/JPL

motivation1
Motivation
  • Designing Space missions with low-cost.
    • Low-thrust propulsion technology are very efficient

BUT

Time of powered flight is long

Very low control authority T/W < 0.01

Risk of failure (continues thrust)

Image Credit: JAXA

low thrust challenges
Low-thrust challenges
  • In multi-body environments trajectories are very sensitive to perturbations ( Launch errors, temporary engine loss, …)
  • Stability is critical for low-thrust missions in multi body environments.
problem statement
Problem statement
  • Current trajectory design methods do not take the risk from loss of control into account.
  • Sensitivity analysis is preformed by Monte Carlo simulation around the reference trajectory which is computationally expensive.
  • Provide methods to reduce the sensitivity and increase the life-time of low-thrust trajectories.
outline of presentation
Outline of Presentation
  • Modeling
  • Indirect stability improvement
  • Direct stability improvement
  • Conclusions and future works
3 body dynamics
3-Body Dynamics

Circular Restricted Three Body Problem

Jacobi constant

3 body dynamics1
3-Body Dynamics

Equilibrium points, periodic orbits and invariant manifolds

trajectory optimization problem
Trajectory Optimization Problem

CRTBP dynamics

J= maximizing payload at final time

Solution: shooting method

stability in the powered flight indirect approach
Stability in the powered flight :Indirect approach
  • How to reduce sensitivity of the reference trajectory to loss of control?
deviation from the reference trajectory for 1 day loss of control
Deviation from the reference trajectory for 1 day loss of control

Remains small

in case of loss of control

stability in the powered flight direct approach
Stability in the powered flight :Direct approach
  • How to improve the life-time characteristics of an optimal trajectory?
  • Important to address planetary protection requirements
direct method inverse dynamics
Direct method:Inverse Dynamics

1- Design an optimal

retargeting trajectory for the

initial condition.

2- Integrate the fuel-optimal

retargeting trajectory

backward in time.

3- extract the required control

to traverse the backward

integrated path.

conclusions
Conclusions

Improving robustness of low-thrust trajectories to loss of control systematically by:

  • Minimizing the angle between controlled and uncontrolled vector field.
  • Back-propagating an optimal retargeting trajectory and extract control using inverse dynamics.
  • The proposed methods are computationally less expensive than traditional approaches.
future works
Future Works
  • Considering the constant specific impulse engines for the transfers.
  • Investigation of the optimality of the inverse dynamics.
  • Design of robust guidance scheme to account for engine performance degradation.