High-precision repeat-groundtrack orbit design and maintenance for Earth observation missions

Abstract

The focus of this paper is the design and station keeping of repeat-groundtrack orbits for Sun-synchronous satellite. A method to compute the semimajor axis of the orbit is presented together with a station-keeping strategy to compensate for the perturbation due to the atmospheric drag. The results show that the nodal period converges gradually with the increase of the order used in the zonal perturbations up to J15. A differential correction algorithm is performed to obtain the nominal semimajor axis of the reference orbit from the inputs of the desired nodal period, eccentricity, inclination and argument of perigee. To keep the satellite in the proximity of the repeat-groundtrack condition, a practical orbit maintenance strategy is proposed in the presence of errors in the orbital measurements and control, as well as in the estimation of the semimajor axis decay rate. The performance of the maintenance strategy is assessed via the Monte Carlo simulation and the validation in a high fidelity model. Numerical simulations substantiate the validity of proposed mean-elements-based orbit maintenance strategy for repeat-groundtrack orbits.

Bounded Relative Orbits in the Zonal Problem via High-Order Poincaré Maps

“…From Figs. 5, 6 and 7 it can be concluded that all the fixed point quantities show a stable behavior for values of n ≥ 10, as already shown in [33]. This reveals the significance of the higher-order perturbations in dealing with the zonal problem and it is actually the reason why the J 15 perturbations are always adopted in this work.…”

“…The degree n needs to be selected according to the required accuracy. As an example, in the work by He et al [33], it was pointed out that n = 15 provided sufficiently stable values of the nodal period for spacecraft orbiting the Earth. Unless otherwise indicated, all the parameters and values reported in this paper are scaled by the characteristic length R = 6378.1363 km and characteristic time R 3 /µ = 806.81099 sec.…”

“…These results are compared, in the right panels, with those computed by a fully numerical propagation of the bounded relative motion. It can be observed that the (for large deviation from the fixed point) and more importantly by the approximation introduced in the procedure of relative motion reconstruction (i.e., simplified formulas (33) and Keplerian motion for δu computation). Note that in case of a chief on a RGT-SS periodic orbit (i.e.…”

An adaptive groundtrack maintenance scheme for spacecraft with electric propulsion

“…The error tolerance y lim in (19) is set according to (33), with T = T (m) = 2π/n * and p =p, resulting in y lim ≃ 2 · 10 −4 rad. This ensures that condition (20) is met with a good safety margin; at the same time, it allows one to successfully counteract the eccentricity variation in (32), according to the discussion in Section 4.3.…”

“…It should now be remarked that the relationship (20) leaves some freedom in the choice of the control specification y lim . Such degree of freedom can be exploited to optimize other relevant performance criteria.…”