On line-of-sight navigation for deep-space applications: A performance analysis

Line-of-Sight (LoS) navigation is an optical navigation technique that exploits the direction to visible celestial bodies, obtained from an onboard imaging system, to estimate the position and velocity of a spacecraft. The directions are fed to an estimation filter, where they are matched with the actual position of the observed bodies,...

Sensor Fusion in Autonomous Navigation for Asteroid Observation Missions

Spacecraft navigation and control is difficult in deep space operations. Especially around asteroids, the irregular gravity field increases the difficulty of estimating the spacecraft trajectory. Autonomous navigation can increase the safety and accuracy for orbit proximity operations. Furthermore, it eliminates the need for continuous...

Extending Attitude Estimation Capability for Agile Precision Target Tracking NanoSats: Hardware Characterisation, Configuration Selection, and Gyro-Stellar based Unscented Calibration Filter Synthesis

Though NanoSats are becoming increasingly capable of featuring active payloads, and acquiring inertial data at arcsec level precision; the payload operational duty-cycle largely remains limited by its data downlink capabilities. NanoSat laser communication terminal (LCT) promises 1 Gbps data downlink capabilities. However, LEO to ground free...

Using the GOCE star trackers for validating the calibration of its accelerometers

A method for validating the calibration parameters of the six accelerometers on board the Gravity field and steady-state Ocean Circulation Explorer (GOCE) from star tracker observations that was originally tested by an end-to-end simulation, has been updated and applied to real data from GOCE. It is shown that the method provides estimates of...

Guidance, Navigation, and Control for Very Small Asteroid Mitigation Missions

Airbus Defence and Space GmbH in Friedrichshafen is the project coordinator of the NEOShield-2 project whose purpose is to develop the technology needed for near-Earth object (NEO) impact prevention. This research is located within the scope of a kinetic impactor mission which typically consists of two spacecraft: impactor and observer. This...

Development and Verification of a Star Tracker Algorithm Chain

Many satellites need to know their attitude. A star tracking system is able to provide this information accurately. The objective of this thesis project is to develop a precise, robust and fast algorithm chain for a star tracker that performs better than the currently used algorithms on that star tracker. The performance of this algorithm chain...

SPS-2: Attitude Control System Design for the Science Mode

Spacecraft attitude refers to the orientation of the spacecraft body axes with respect to the inertial reference frame. Attitude determination and control is the estimation of the current orientation of a satellite and controlling or changing it on demand to reach a desired orientation. The SPS-2 Attitude Control System consists of four modes:...

Development an Verification of the Electro-Optical and Software Modules of the Facet Nano Star Sensor

This Thesis report is written for the space community, specially for people interested in the field of nanosatellites, who know how star trackers work, but are unfamiliar with their operations and limitations in an earth observation mission. To introduce users to the topic, this document is primarily concerned with a single aperture star tracker...

Exploring the possibilities for star-tracker assisted calibration of the six individual GOCE accelerometers

A method has been developed and tested for estimating calibration parameters for the six accelerometers on board the Gravity field and steady-state Ocean Circulation Explorer (GOCE) from star tracker observations. These six accelerometers are part of the gradiometer, which is the prime instrument on board GOCE. It will be shown that by taking...

Study of an attitude acquisition measurement technique using the ESA starmapper: Part I: Executive summary

The study deals with the rotational motion of a spin-stabilized spacecraft equipped with a V-slit sun sensor and the X-slit ESA starmapper. Assuming complete absence of an a priori attitude estimate, it is required to produce a rough estimate of the spacecraft attitude motion. It was assumed that sensor misalignments, external torques and...

Study of an attitude acquisition measurement technique using the ESA starmapper: Part two: final report

The study deals with the rotational motion of a spin-stabilized spacecraft equipped with a V-slit sun sensor and the X-slit ESA starmapper. Assuming complete absence of an a priori attitude estimate, it is required to produce a rough estimate of the spacecraft attitude motion. It was assumed that sensor misalignments, external torques and...

Digital filtering methods, with applications to spacecraft attitude determination in the presence of modelling errors. Part II: Extension of theory, and applications

The present issue is the second and final part of a report describing the results of a study about digital filtering. The first part is available as the report NLR TR 760U8 U. The report considers a number of digital filtering methods and gives examples of their application. The methods include batch processing methods and recursive methods....