4:00 p.m.-5:00 p.m.
2164 Martin Hall, DeWalt Seminar Room & Via Zoom
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SPEAKER: Ariadna Farres Basiana
The Geometry Behind Station-keeping at the L1/L2 Libration Points
ABSTRACT: Over the years Libration Point orbits have become relevant in space applications, as the regions around the L1 and L2 points in the Circular Restricted Three-Body (CRTBP) are ideal for deep space observations like the Roman Space Telescope (RST) and the James Webb Space Telescope (JWST) or space weather missions like the Solar and Heliospheric Observatory (SOHO) and the Space Weather Follow-On (SWFO). The periodic and quasi-periodic motion around L1 /L2 is unstable, and station-keeping maneuvers are required to cancel this instability and overcome the effect of perturbations and uncertainties. Some of the perturbations come from: orbit determination errors (ODE) where the uncertainties on the position and velocity of the spacecraft affect the size of the planned SK maneuvers; maneuver execution errors (MEE) which will deviate the trajectory from the desired nominal path; solar radiation pressure uncertainties (SRP) due to attitude changes that affect the orbits trajectory between maneuvers; and momentum unloads (MUs) which are small maneuvers performed to desaturate the spacecraft’s reaction wheels used for attitude control. The size of the station-keeping maneuvers will depend on the different perturbation and can be hard to predict, hence for preliminary mission analyses Monte Carlo simulations are required to estimate the delta-v cost of orbital maintenance.
In this talk we will describe the classical station-keeping strategy used in seeral NASA mission like SOHO and JWST. The so called, x-axis velocity constraint at the plain crossing, where we find the delta-v required to guarantee that at the 4th plane crossing Vx = 0. This condition ensures that the spacecraft’s trajectory will continue to orbit around the Libration point. We will also introduce the Floquet mode reference frame and show how it can be used describe the geometry behind this station-keeping strategy. As we will see the Floquet mode reference frame can help es estimate the cost of station-keeping subject to different mission constraints on the thrust directions, SRP uncertainties or MUs performance.
BIO: Dr. Farres has a PhD in Applied Mathematics by the University of Barcelona and specializes in astrodynamics and solar sails. She is currently a Research Fellow at NASA Goddard Space Flight Center, collaborating Flight Dynamics and Mission Design team on mission like Nancy Grace Roman Space Telescope (RST) and Space Weather Follow On (SWFO).
This Event is For: All Students • Graduate • Undergraduate • Faculty • Staff