Orbit deployment and drag control strategy for formation flight while minimizing collision probability and drift

Abstract

The compact form factor of nanosatellites or even smaller satellites makes them predestined for distributed systems such as formations, constellations or large swarms. However, when it comes to orbit insertion of multiple satellites, these ride share payloads have constrains in the deployment parameters such as sequence, direction, velocity and time interval. Especially for formation flight missions without propulsion, where the satellites should minimize their relative distance drift either passively or by atmospheric drag control, the initial ejection parameters must find a proper trade-off between collision probability and relative drift. Hence, this article covers short-term (first orbit) collision analysis, long-term (30 days) drift analysis and atmospheric drag control strategy for long-term distance control of multiple satellites. The collision analysis considers various orbit deployment parameters such as insertion direction and tolerance, orbital elements of insertion and time span. To cover the parameter space, a Monte Carlo simulation was conducted to identify the impact of these parameters. It showed that for collision probability the major factor is the time span between two ejections and the precision of the deployment vector. For long-term drift analysis, orbit perturbation such as atmosphere and J2 terms are considered. The result showed that for drift minimizing, minimizing the along-track variation is more substantial than reducing the time span between ejections. Additionally, a drag control strategy to reduce the relative drift of the satellites is described. The results have been applied on the S-NET mission, which consists of four nanosatellites with the task to keep their relative distance within 400 km to perform intersatellite communication experiments. The flight results for orbital drift show equal or better performance (0.1-0.7 km/day) compared to the worst-case simulation scenario, implying that orbit perturbation was chosen correctly and all orbit injection tolerances were within specified range. The drag control maneuver showed good matching to the flight results as well with a deviation for the maneuver time of approximately 10%.

Spectral Light Curve Simulation for Parameter Estimation from Space Debris

“…The target attitude is calculated from the torque free Euler equations [24,26], under the premise that its rotation state remains constant. In most cases this is a valid assumption, as typical values for environmental torques acting on objects in Earth orbit are on the order of 10 −4 to 10 −7 N m [28][29][30], which are too small to have a significant effect on the objects' rotation over the time span of a simulated pass (usually less than 10 min). Analysis of historical spin periods for satellites such as TOPEX/Poseidon and Envisat have revealed changes in rotation periods of approximately 1.1 and 0.3 degrees per year, respectively [28,31].…”

Autonomous formation flight using solar radiation pressure

“…Only a few missions have been realized so far, such as Prisma [8], CanX-4/5 [13] and Hawkeye [14]. Very recently, the Net-Sats [15] formation flight mission has been launched; Yoon [16] demonstrates the use of drag for limited relative orbit control, i.e., the keeping distance between different satellites for collision avoidance. All these missions have been primarily experimental in nature.…”

Satellite design optimization for differential lift and drag applications

“…Due to its promising benefits, differential drag methods have been investigated by different research groups worldwide (see Refs. [4][5][6][7][8][9]) and have regularly been demonstrated in-orbit [10][11][12][13]. However, the control authority of differential drag is primarily constrained to in-plane motion.…”