ESTCube-1 nanosatellite for electric solar wind sail in-orbit technology demonstration

Proceedings of the Estonian Academy of Sciences, 2014

The scientific mission of ESTCube-1, launched in May 2013, is to measure the Electric solar wind sail (E-sail) force in orbit. The experiment is planned to push forward the development of E-sail, a propulsion method recently invented at the Finnish Meteorological Institute. E-sail is based on extracting momentum from the solar wind plasma flow by using long thin electrically charged tethers. ESTCube-1 is equipped with one such tether, together with hardware capable of deploying and charging it. At the orbital altitude of ESTCube-1 (660-680 km) there is no solar wind present. Instead, ESTCube-1 shall observe the interaction between the charged tether and the ionospheric plasma. The ESTCube-1 payload uses a 10-meter, partly two-filament E-sail tether and a motorized reel on which it is stored. The tether shall be deployed from a spinning satellite with the help of centrifugal force. An additional mass is added at the tip of the tether to assist with the deployment. During E-sail experiment the tether shall be charged to 500 V potential. Both positive and negative voltages shall be experimented with. The voltage is provided by a dedicated high voltage source and delivered to the tether through a slip ring contact. When the negative voltage is applied to the tether, the satellite body is expected to attract electron flow capable of compensating for the ion flow, which runs to the tether from the surrounding plasma. With the positive voltage applied, onboard cold cathode electron guns are used to remove excess electrons to maintain the positive voltage of the tether. In this paper we present the design and structure of the tether payload of ESTCube-1.

Proceedings of the Estonian Academy of Sciences, 2014

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 during the scientific experiment. ESTCube-1 is a one-unit CubeSat launched on 7 May 2013, 2:06 UTC on board the Vega VV02 rocket. Its primary mission is to measure the Coulomb drag force exerted by a natural plasma stream on a charged tether and, therefore, to perform the basic proof of concept measurement and technology demonstration of electric solar wind sail technology. The attitude determination system uses three-axis magnetometers, three-axis gyroscopic sensors, and two-axis Sun sensors, a Sun sensor on each side of the satellite. While commercial off-the-shelf components are used for magnetometers and gyroscopic sensors, Sun sensors are custombuilt based on analogue one-dimensional position sensitive detectors. The attitude of the satellite is estimated on board using an Unscented Kalman Filter. An ARM 32-bit processor is used for ADCS calculations. Three electromagnetic coils are used for attitude control. The system is characterized through tests and simulations. Results include mass and power budgets, estimated uncertainties as well as attitude determination and control performance. The system fulfils all mission requirements.

IEEE Aerospace Conference, 2019

An Electric Sail (E-Sail) propulsion system consists of long, thin tethers-positively-charged wires extending radially and symmetrically outward from a spacecraft. Tethers must be biased using a high-voltage power supply to ensure that the solar wind produces thrust. While the E-Sail concept shows great promise for flying heliopause missions with higher characteristic acceleration than solar sails, there are significant technical challenges related to deploying and controlling multiple tethers. A typical full-scale design involves a hub and spoke arrangement of 10 to 100 tethers, each 20 km long. In the last 20 years, there have been multiple space mission failures due to tether deployment and control issues, and most configurations involved a single tether. This paper describes an effort to develop and test a simple yet robust single-tether deployment system for a two-6U CubeSat configuration. The project included the following: a) Tether dynamic modeling/simulation b) E-Sail single-tether prototype development and testing c) Space environmental effects testing to identify best materials for further development. These three areas of investigation were needed to provide technical rationale for an E-Sail flight demonstration mission that is expected to be proposed for the 2022 timeframe.

The electric solar wind sail (E-sail) is a space propulsion concept which uses the natural solar wind dynamic pressure for producing spacecraft thrust. In its baseline form the Esail consists of a number of long, thin, conducting and centrifugally stretched tethers which are kept in a high positive potential by an onboard electron gun. The methods gains its efficiency from the fact that the effective sail area of the tethers can be millions of times larger than the physical area of the thin tethers wires which offsets the fact that the dynamic pressure of the solar wind is very weak. Indeed, according to the most recent published estimates, an E-sail of 1 N thrust and 100 kg mass could be built in rather near future, providing a revolutionary level of propulsive performance (specific acceleration) for travel in the solar system. Here we give an overview and status report of the ongoing technical development work of the E-sail, covering tether construction, overall mechanical design alternatives, guidance and navigation strategies and dynamical and orbital simulations.

Review of Scientific Instruments, 2010

The electric solar wind sail ͑E-sail͒ is a space propulsion concept that uses the natural solar wind dynamic pressure for producing spacecraft thrust. In its baseline form, the E-sail consists of a number of long, thin, conducting, and centrifugally stretched tethers, which are kept in a high positive potential by an onboard electron gun. The concept gains its efficiency from the fact that the effective sail area, i.e., the potential structure of the tethers, can be millions of times larger than the physical area of the thin tethers wires, which offsets the fact that the dynamic pressure of the solar wind is very weak. Indeed, according to the most recent published estimates, an E-sail of 1 N thrust and 100 kg mass could be built in the rather near future, providing a revolutionary level of propulsive performance ͑specific acceleration͒ for travel in the solar system. Here we give a review of the ongoing technical development work of the E-sail, covering tether construction, overall mechanical design alternatives, guidance and navigation strategies, and dynamical and orbital simulations.

Proceedings of the Estonian Academy of Sciences, 2014

This work describes the final design and implementation of the electrical power system for ESTCube-1, a 1-unit CubeSat tasked with testing the electrostatic tether concept and associated technologies for the electric solar wind sail in polar low Earth orbit. The mission required an efficient and reliable power system to be designed that could efficiently handle highly variable power requirements and protect the satellite from damage caused by malfunctions in its individual subsystems, while using only commercial-off-the-shelf components. The system was developed from scratch and includes a novel redundant standalone nearly 90% efficient maximum power point tracking system, based on a commercially available integrated circuit, a lithiumion battery based fault-tolerant power storage solution, a highly controllable and monitorable power distribution system, capable of sustaining loads of up to 10 W, and an AVR microcontroller based control solution, heavily utilizing non-volatile ferroelectric random access memories. The electrical power system was finalized in January 2013 and was launched into orbit on 7th of May, 2013. In this paper, we describe the requirements for the subsystem, the design of the subsystem, pre-flight testing, and flight qualification.

Acta Astronautica, 2016

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 the satellite to deploy a 10 m long tether. The required spin rate was a minimum of one rotation per second. The actuators used were three electromagnetic coils, each able to produce a magnetic moment of up to 0.1 A m 2. In this paper, we describe the design of the attitude control system, implementation of the spin controller and the in-orbit performance of the system. In addition we describe the effect that a residual magnetic moment had on the attitude control of the satellite and the measures taken to overcome this issue. During testing of the satellite, ESTCube-1 achieved the highest known spin rate of 841°/s for small scale satellites. The satellite ended its operations on the 19th of May, 2015 after 2 years in orbit.

2008

The "NanoSail-D" mission is currently scheduled for launch onboard a Falcon Launch Vehicle in the late June 2008 timeframe. The NanoSail-D, a CubeSat-class satellite, will consist of a sail subsystem stowed in a Cubesat 2U volume integrated with a CubeSat 1U volume bus provided by the NASA Ames Research Center (ARC). Shortly after deployment of the NanoSail-D from a Poly Picosatellite Orbital Deployer (P-POD) ejection system, the solar sail will deploy and mission operations will commence. This demonstration flight has two primary mission objectives: 1) to successfully stow and deploy the sail and 2) to demonstrate de-orbit functionality. Given a nearterm opportunity for launch, the project was met with the challenge of delivering the flight hardware in approximately six months, which required a significant constraint on flight system functionality. As a consequence, passive attitude stabilization will be achieved using permanent magnets to de-tumble and orient the body with the magnetic field lines and then rely on atmospheric drag to passively stabilize the sailcraft in an essentially maximum drag attitude. This paper will present an introduction to solar sail propulsion systems, overview the NanoSail-D spacecraft, describe the performance analysis for the passive attitude stabilization, and present a prediction of flight data results from the mission.

Acta Astronautica, 2006

The magneto-plasma sail (mini-magnetospheric plasma propulsion) produces the propulsive force due to the interaction between the artificial magnetic field around the spacecraft inflated by the plasma and the solar wind erupted from the Sun with a speed of 300-800 km/s. The principle of the magneto-plasma sail is based on the magnetic sail whose original concept requires a huge mechanical coil structure, which produces a large magnetic field to capture the energy of the solar wind. Meanwhile in the case of the magneto-plasma sail, the magnetic field will be expanded by the inertia of plasma flow to a few tens of kilometer in diameter, resulting in a thrust of a few Newton R. Winglee's group of the University of Washington originally proposed the idea of magnetic field inflation by the plasma. This paper investigates the characteristics of the magneto-plasma sail by comparing it with the other low-thrust propulsion systems (i.e., electric propulsion and solar sail), and the potential of its application to near future outer planet missions is studied. Furthermore, an engineering validation satellite concept is proposed in order to confirm the propulsion system specification and operation methodology. The main features are summarized as: (1) The satellite mass is around 180 kg assuming the H-IIA piggyback launch. (2) Since the magnetopause of the Earth magnetosphere is about 10 Re at Sun side and the bow shock is located at about 13 Re from the Earth, the satellite is injected into an orbit with 250 km perigee altitude and 20 Re apogee distance where apogee is located at the Sun side. (3) The magneto-plasma sail is turned on only in the vicinity of apogee outside the Earth's magnetosphere. (4) The thrust is estimated by the orbit determination result, and the plasma wind monitor is installed on the satellite to establish the relationship between the solar wind and the thrust.

Investigations into a propellant-less method to propel scientific spacecraft to the deep reaches of our solar system and beyond have commenced within the MSFC Advanced Concepts Office (ACO). The primary goal of this work is to fully document if such an idea can become reality and determine what near term spacecraft can be designed, developed, and flown before this decade is out as a technology demonstration mission. This will allow us to develop a larger propulsion system for a Heliopause Electrostatic Rapid Transportation System (HERTS) to examine the edge of the solar system within ten to fifteen years. The primary design space of the propellant-less propulsion system are 5 km to 10 km long thin bare wires that have a positive charge applied to them. These positively charged wires would repel the positively charged protons that are in the naturally occurring solar wind, thereby producing thrust to the spacecraft. The work, performed this summer, is focused on the conceptual development of such a propulsion system integrated into a 6U CubeSat (10 cm x 20 cm x 30 cm). A proposal is being developed by ACO for a 6U CubeSat technology demonstration mission (less than 12 kg mass) that could be developed at the MSFC for less than $5 million (fixed price) and flown on either the first or second launch of the Space Launch System as a secondary payload. This work directly applies to the HERTS activity mentioned earlier. Nomenclature