GNC of a cargo spacecraft for on-orbit servicing of Herschel at L2

in IAC 2022 congress proceedings, 73rd International Astronautical Congress (IAC) (2022, September)

t is anticipated that space exploration will need to rely on In Situ Resource Utilization (ISRU) in order toextend spacecraft lifetime and/or reduce the missions cost and/or the cruise time. For the Moon ... [more ▼]

t is anticipated that space exploration will need to rely on In Situ Resource Utilization (ISRU) in order toextend spacecraft lifetime and/or reduce the missions cost and/or the cruise time. For the Moon and, inthe future, Mars colonization, relying on in-situ resources is a necessary step to become independent fromthe Earth. The possibility to produce resources on the Moon is advantageous for those missions that aretoo far from the Earth to be resupplied. At the SnT Research Centre, the Luxembourg Space Agency issupporting a feasibility study to assess the benefit of on-orbit servicing (OOS), exploiting lunar resourcesfor the Herschel Space Observatory. Herschel ended its operations in 2013 as a consequence of the depletionof its coolant and, in turn, of the capability of cooling down its instruments. To extend its operations,a resupply mission has been envisaged relying on an adapted cargo spacecraft employed in lunar gatewayoperations. This paper deals with the trajectory design and optimization of the cargo on its journey from theMoon to rendezvous with Herschel and with orbit and attitude control. Considering Herschel’s orientationon its orbit, with the sunshield in the direction of the Sun and the need to access to Herschel’s rear panelto perform the resupply operation, a final approach along the negative x-axis, where the primaries lie, isconsidered. A multiple shooting technique is used to perform a flanking manoeuvre. Moreover, an attitudecontrol algorithm is adopted to track the attitude trajectory provided by the guidance algorithms which, inturn, ensure minimum thrusting errors of the cargo spacecraft and a continuous visibility of Herschel. Infuture works, different perturbations will be considered and angular rates induced by the movement of therobotic arms will be compensated [less ▲]

Formation design of an inter-satellite link demonstration mission

Scientific Conference (2022, June)

The problem of secular growth of the inter-satellite induced by the J2 perturbations has been widely exploredin the literature. In this paper, we study the influence of altitude and initial mean anomaly ... [more ▼]

The problem of secular growth of the inter-satellite induced by the J2 perturbations has been widely exploredin the literature. In this paper, we study the influence of altitude and initial mean anomaly of the chief on theinter-satellite distance growth in a classical trailing formation. Mean elements are converted into osculatingones and then in Cartesian coordinates that are propagated together in the ECI frame. Preliminary resultsshows that zonal harmonics are responsible for a steep distance drift when the formation is inserted inthe vicinity of ±45 and ±135 degrees of mean anomaly in a polar orbit. Distance-invariant solutions aredetermined in term of the mean anomaly and characterized in terms of the difference between the averagerelative distance and the initial one and of the amplitude of the osculating distance. Finally, after the inter-satellite distance has grown to an unacceptable level, the electric thruster onboard of the deputy spacecraftis leveraged in order to reset the deputy’s orbit to the distance invariant mean elements. A finite-time LinearQuadratic Regulator (FTLQR) is designed and validated within a high-fidely dynamics framework [less ▲]

Attitude Task Allocation and Control in a Swarm of Magnetically Controlled CubeSats

in CDSR 2021 conference proceedings, 8th International Conference on Control, Dynamic Systems, and Robotics (CDSR'21) (2021)

The paper delineates the magnetic controller gains tuning procedure for an active magnetic attitude control system of a CubeSat in the ISS orbit. The optimization is conducted for arbitrary required ... [more ▼]

The paper delineates the magnetic controller gains tuning procedure for an active magnetic attitude control system of a CubeSat in the ISS orbit. The optimization is conducted for arbitrary required attitude given in the orbital reference frame of the spacecraft. The study has been conducted as a part of the Skoltech University project to deploy a swarm of 3U CubeSats for collective gamma-ray bursts detection, which requires the satellites' coordinated attitude control. We consider four identical CubeSats exhibiting swarm behaviour by optimal attitude task allocation on receipt of a command from the mission control center. The first part of this study shows how to obtain the controller gains via linearization of the spacecraft rotational dynamics in the vicinity of the required attitude regime and subsequent numerical optimization (carried out in terms of Floquet theory). The second part shows the collective attitude control scenario. The task of the swarm is to ensure maximum sky coverage around a principal direction uplinked to the spacecraft. The task extends to ensuring the maximum collective stability of the swarm through implementing the optimization algorithm. [less ▲]

Hybrid Attitude Control for Nano-Spacecraft: Reaction Wheel Failure and Singularity Handling

in Journal of Guidance Control and Dynamics (2020), 44(3), 548-558

This paper addresses the attitude control of nano-spacecraft with three reaction wheels and three magnetorquers in low Earth orbits, and develops algorithms to maintain control when any one of the ... [more ▼]

This paper addresses the attitude control of nano-spacecraft with three reaction wheels and three magnetorquers in low Earth orbits, and develops algorithms to maintain control when any one of the reaction wheels completely fails. In the event of a reaction wheel failure, it is shown that the key challenge of maintaining accurate autonomous three-axis tracking is a problem of singularity avoidance in control allocation. In particular, control law singularities occur depending on the type of orbit, the environment, and the attitude, where the system is no longer controllable. Two algorithmic singularity avoidance techniques based on singularity prediction and artificial potential functions are proposed. In addition, an optimized reaction wheel configuration is proposed to enhance singularity avoidance capability. To illustrate the effectiveness of the singularity avoidance control laws, they are tested in simulations that include the effects of perturbing environmental torques, reaction wheel jitter, and actuator misalignment. [less ▲]