Indrek Sünter

Tartu Observatory · Space Research Centre

The Copernicus Sentinel-2 mission operated by the European Space Agency (ESA) provides comprehensive and continuous multi-spectral observations of all the Earth’s land surface since mid-2015. Clouds and cloud shadows significantly decrease the usability of optical satellite data, especially in agricultural applications; therefore, an accurate and r...

This paper presents two technology experiments – the plasma brake for deorbiting and the electric solar wind sail for interplanetary propulsion – on board the ESTCube-2 and FORESAIL-1 satellites. Since both technologies employ the Coulomb interaction between a charged tether and a plasma flow, they are commonly referred to as Coulomb drag propulsio...

Short temporal baseline regular Synthetic Aperture Radar (SAR) interferometry is a tool well suited for wide area monitoring of agricultural activities, urgently needed in European Union Common Agricultural Policy (CAP) enforcement. In this study, we demonstrate and describe in detail, how mowing and ploughing events can be identified from Sentinel...

We propose a distributed close-range survey of hundreds of asteroids representing many asteroid families, spectral types and sizes. This can be implemented by a fleet of nanospacecraft (e.g., 4-5-unit CubeSats) equipped with miniature imaging and spectral instruments (from near ultraviolet to near infrared). To enable the necessary large delta-v, e...

This paper is republished in Acta Astronautica as "Coulomb drag propulsion experiments of ESTCube-2 and FORESAIL-1": https://www.researchgate.net/publication/337626758_Coulomb_drag_propulsion_experiments_of_ESTCube-2_and_FORESAIL-1\\ In this paper, a novel, efficient, lightweight and cost-effective method for satellite deorbiting is presented. The...

This paper presents the in-orbit performance of the ESTCube-1 attitude control system that used electromagnetic actuators to achieve a high angular velocity. ESTCube-1 is a one-unit CubeSat that aimed to perform the first electric solar wind sail experiment. The attitude control system was designed to provide enough centrifugal force by spinning up...

This paper presents the preliminary results of structural and electrical testing of a lightweight and power-efficient dual-camera system for European Student Earth Orbiter (ESEO). ESEO is an educational micro-satellite for monitoring the radiation environment and taking images of Earth in Low Earth Orbit (LEO) at the planned altitude of 520 km. The...

This paper is republished in Acta Astronautica as "Coulomb drag propulsion experiments of ESTCube-2 and FORESAIL-1": https://www.researchgate.net/publication/337626758_Coulomb_drag_propulsion_experiments_of_ESTCube-2_and_FORESAIL-1 // Here we present the preliminary mission analysis for the ESTCube-2 three-unit CubeSat, which is designed to test Co...

This paper presents the design, development and pre-launch testing of a lightweight and power-efficient dual-camera system for European Student Earth Orbiter (ESEO). ESEO is an educational microsatel-lite for monitoring the radiation environment in Low Earth Orbit (LEO) and taking images of Earth. The primary camera of the payload has a 4.4 mm tele...

This paper is republished in Acta Astronautica as "Coulomb drag propulsion experiments of ESTCube-2 and FORESAIL-1": https://www.researchgate.net/publication/337626758_Coulomb_drag_propulsion_experiments_of_ESTCube-2_and_FORESAIL-1 // Here we present the preliminary mission design for the ESTCube-2 three-unit CubeSat. Its main mission is to test Co...

Space missions are dynamic in nature and therefore the on-board software on spacecraft often needs to be updated after deployment into space. Nanosatellites are no exception, but their update options are often not implemented. In this paper four variants of a method are demonstrated for remote firmware updates on nanosatellite systems with low memo...

This paper presents the characterization and in-orbit validation of the ESTCube-1 attitude determination system (ADS). ESTCube-1 is a one-unit CubeSat built by students and launched on May 7, 2013, to a Sun-synchronous, 700-km, polar low Earth orbit. Its primary mission is to centrifugally deploy a tether as a part of the first in-orbit demonstrati...

ESTCube-1 is a one-unit CubeSat that has been in orbit since May 2013. It was launched to a Sun-synchronous 670 km altitude polar low Earth orbit, and its primary mission objective was to centrifugally deploy a tether as a part of the first in-orbit demonstration of electric solar wind sail (E-sail) technology. The electrical power system, the comm...

This conference paper is largely based on "ESTCube-1 In-Orbit Experience and Lessons Learned": https://www.researchgate.net/publication/282356730_ESTCube-1_In-Orbit_Experience_and_Lessons_Learned_Harry_Rowe_Mimno_Award_2016 // ESTCube-1 is a one-unit CubeSat that has been in orbit since May 2013. It was launched to a Sun-synchronous 670 km altitud...

This paper presents the mission analysis, requirements, system design, system level test results, as well as mass and power budgets of a 1-unit CubeSat ESTCube-1 built to perform the first in-orbit demonstration of electric solar wind sail (E-sail) technology. The E-sail is a propellantless propulsion system concept that uses thin charged electrost...

This paper presents the design, development, and pre-launch characterization of the ESTCube-1 Attitude Determination and Control System (ADCS). The design driver for the ADCS has been the mission requirement to spin up the satellite to 360 deg × s–1 with controlled orientation of the spin axis and to acquire the angular velocity and the attitude du...

This paper presents a study of a high rate closed-loop spin controller that uses only electromagnetic coils as actuators. The controller is able to perform spin rate control and simultaneously align the spin axis with the Earth's inertial reference frame. It is implemented, optimised and simulated for a 1-unit CubeSat ESTCube-1 to fulfil its missio...

This paper presents the design, implementation, and pre-launch test results of the Command and Data Handling Subsystem (CDHS) for ESTCube-1. ESTCube-1 is a one-unit Cube Sat, which will perform an electric solar wind sail experiment. The development process of the CDHS for ESTCube-1 was focused on robustness and fault tolerance. A combination of ho...

This paper presents a novel low-power imaging system for nanosatellite proximity operations. A robust independent camera module with on-board image processing, based on the ARM Cortex-M3 microcontroller and fast static random access memory, has been developed and characterized for the requirements of the ESTCube-1 mission. The imaging system, optim...

This paper presents ESTCube-1 nanosatellite, mission status and ground segment. ESTCube-1 is a single unit CubeSat that was launched into 670 km altitude sun-synchronous polar orbit in May 2013. Almost all of the nanosatellite subsystems have been developed by students in Estonia. ESTCube-1 takes the first step in realising electric solar wind sail...