Diffractive Sail-Based Displaced Orbits for High-Latitude Environment Monitoring

Abstract

This paper analyzes the possibility of maintaining a circular displaced non-Keplerian orbit around the Sun by means of a Sun-facing diffractive sail. With the goal of monitoring the Earth’s high-latitude regions, the spacecraft is required to track its displaced orbit at an angular velocity equal to the mean motion of the planet. In doing so, the spacecraft keeps a constant average phase shift with respect to Earth’s angular position along its orbit, allowing the objectives of the scientific mission to be achieved. The diffractive sail, recently proposed by Swartzlander and chosen in this paper as the spacecraft’s primary propulsion system, is a special photonic solar sail in which the membrane film is covered by an advanced diffractive metamaterial. In particular, a Sun-facing diffractive sail with a grating at normal incidence generates radial and transverse thrust components of equal magnitude; that is, the thrust vector is tilted 45 degrees from the Sun-spacecraft line. This peculiarity enables the diffractive sail to maintain a family of circular displaced non-Keplerian orbits, each of which is characterized by unique values of radius and a lightness number for an assigned value of spacecraft displacement relative to the Ecliptic. A comparison with the ideal reflecting sail shows that the diffractive sail performs better because for the same overall spacecraft mass, the latter needs about 30% less surface area exposed to the Sun. Finally, this paper discusses the classical stability problem, assuming an error in orbit insertion of the diffractive sail-based spacecraft. In this context, extensive numerical simulations show that such displaced orbits are marginally stable.

Solar Sail-Based Mars-Synchronous Displaced Orbits for Remote Sensing Applications

“…is an explicit function of {ν, ν} according to Equations ( 15)-( 18), so it changes throughout the period of revolution of Mars. However, as already shown in [27], its mean integral value with respect to ν, that is, the function…”

“…By replicating the procedure described in Ref. [27], in this section we quantify the Mars-spacecraft distance, showing that it depends on four parameters, namely, the DNKO radius ρ, the DNKO displacement H, the true anomaly ν of Mars, and the point in the planetary orbit (described by the angle ν) at which the spacecraft and Mars have the same angular position in their (always parallel) planes of motion.…”

“…Finally, Heiligers et al [25] analyzed the possibility of using a classical solar sail to generate artificial equilibrium points and displaced periodic orbits around small bodies in the solar system such as asteroids or binary asteroid systems. More recently, Bassetto et al [26,27] studied the performance of Zubrin's magnetic sails [28][29][30] and Swartzlander's diffractive sails [6][7][8] in maintaining circular DNKOs of assigned characteristics, with applications in a typical Earth-based mission scenario. From the point of view of the spacecraft dynamics along a DNKO, station keeping has also been studied in the context of three-body problem periodic orbits, which also suffer from deviations from nominal periodic behavior due to unmodeled physics.…”

Optimal Trajectories of Diffractive Sail to Highly Inclined Heliocentric Orbits

“…More precisely, comparing a diffractive and a reflective sail on the same reference mission for the same area-to-mass ratio, the diffractive sail allows the target to be reached in a shorter flight time or, for the same mission time, the diffractive sail allows the use of a smaller area-to-mass ratio than the reflective sail [21]. Recently, the performance of this type of propellantless systems has been studied in a number of mission scenarios [22], including orbit raising [19], interplanetary transfers [23], and the generation of heliocentric non-Keplerian orbits [24].…”