Interplanetary Kite-craft Accelerated By Radiation Of The Sun Research Articles

Active Shape Control of Membrane Structures Using Spin-Synchronous Vibrations

A novel approach for shape control of membrane structures is presented to realize their use in three-dimensional and variable configurations. The shape control is accomplished by exciting a spinning membrane. The membrane forms a shape consisting of several vibration modes, depending on the input frequency, and the wave surface stands still when its frequency is synchronized with the spin rate; that is, the wave propagation and the spin cancel each other, resulting in a static wave surface in the inertial frame. This idea enables control of continuous membrane structures with large deformation using fewer actuators than conventional methods. This paper describes the general theory of the static wave-based shape control. The mathematical model of membrane vibration, the classification of control input, and the control system for exciting a static wave are summarized. The proposed method is demonstrated through a ground experiment. A 1 m large polyimide film is rotated and vibrated in a vacuum chamber, and the output shape is measured using a real-time depth sensor. It is shown that the observed shapes agree with numerical simulation results. An additional simulation that models the Japanese solar sail Interplanetary Kite-craft Accelerated by Radiation Of the Sun (IKAROS) demonstrates that the proposed method also works with a practically large-scale membrane in the space environment.

Analytical Investigation of Global Deployed Shape of a Spinning Solar Sail Membrane

In this paper, the deployed shape of spinning square solar sails was investigated through dynamic nonlinear finite element analysis of the full model of the solar power sail of the world’s first solar sail: Interplanetary Kite-craft Accelerated by Radiation of the Sun (IKAROS). The on-orbit photographs of IKAROS revealed that the sail membrane was deformed toward the sun and the membrane maintained its deployed shape during very low-spin-rate operations. To clarify the mechanism of the deformation and high stiffness, the authors of the present study previously performed deployed shape analyses of one-quarter of one square sail by employing Abaqus and reported that the phenomenon was probably caused by curvatures of thin-film devices attached to the membrane. In this study, a finite element model of the entire square sail of IKAROS was created. Furthermore, deployed shape analysis under several combinations of curvatures and spin rates was conducted by employing the dynamic solver “Abaqus/Explicit.” The results indicated that the sail deformations were induced by the curvatures of thin-film devices and that umbrella and saddle shapes appeared owing to the curvatures. The results also indicated that the electric harnesses between the sail and spacecraft supported the sail shape when the spin rate was low.

Solar power sail mission of OKEANOS

The solar power sail is an original Japanese concept in which electric power is generated by thin-film solar cells attached on the solar sail membrane. Japan Aerospace Exploration Agency (JAXA) successfully demonstrated the world’s first solar power sail technology through IKAROS (Interplanetary Kite-craft Accelerated by Radiation of the Sun) mission in 2010. IKAROS demonstrated photon propulsion and power generation using thin-film solar cells during its interplanetary cruise. Scaled up, solar power sails can generate enough power to drive high specific impulse ion thrusters in the outer planetary region. With this concept, we propose a landing or sample return mission to directly explore a Jupiter Trojan asteroid using solar power sail-craft OKEANOS (Oversize Kite-craft for Exploration and AstroNautics in the Outer Solar System). After rendezvousing with a Trojan asteroid, a lander separates from OKEANOS to collect samples, and perform in-situ analyses in three proposed mission sequences, including sending samples back to Earth. This paper proposes a system design for OKEANOS and includes analyses of the latest mission.

Deployable Camera (DCAM3) System for Observation of Hayabusa2 Impact Experiment

An asteroid exploration probe “Hayabusa2”, that was developed by Japan Aerospace Exploration Agency (JAXA), was launched on December 3rd, 2014 to challenge complicated and accurate operations during the mission phase around the C-type asteroid 162137 Ryugu (1999 JU3) (Tsuda et al. in Acta Astron. 91:356–362, 2013). An impact experiment on a surface of the asteroid will be conducted using the Small Carry-on Impactor (SCI) system, which will be the world’s first artificial crater creation experiment on asteroids (Saiki et al. in Proc. International Astronautical Congress, IAC-12.A3.4.8, 2012, Acta Astron. 84:227–236, 2013a; Proc. International Symposium on Space Technology and Science, 2013b). We developed a new micro Deployable CAMera (DCAM3) system for remote observations of the impact phenomenon applying our conventional DCAM technology that is one of the smallest probes in space missions and gained a great success in past Japanese mission IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). DCAM3 is a miniaturized separable unit that contains two cameras and radio communication devices for transmission image data to the mothership “Hayabusa2”, and it observes the impact experiment at an unsafe region in where the “Hayabusa2” is difficult to stay because of a risk of exploding and impacting debris hitting. In this paper, we report details of the DCAM3 system and development results as well as our mission plan for the DCAM3 observation during the SCI experiment.

Switch programming of reflectivity control devices for the coupled dynamics of a solar sail

As demonstrated in the Interplanetary Kite-craft Accelerated by Radiation Of the Sun (IKAROS), reflectivity control devices (RCDs) are switched on or off independently with each other, which has nevertheless been ignored by many previous researches. This paper emphasizes the discrete property of RCDs, and aims to obtain an appropriate switch law of RCDs for a rigid spinning solar sail. First, the coupled attitude–orbit dynamics is derived from the basic solar force and torque model into an underdetermined linear system with a binary set constraint. Subsequently, the coupled dynamics is reformulated into a constrained quadratic programming and a basic gradient projection method is designed to search for the optimal solution. Finally, a circular sail flying in the Venus rendezvous mission demonstrates the model and method numerically, which illustrates approximately 103km terminal position error and 0.5m/s terminal velocity error as 80 independent RCDs are switched on or off appropriately.

Microparticle impact calibration of the Arrayed Large-Area Dust Detectors in INterplanetary space (ALADDIN) onboard the solar power sail demonstrator IKAROS

The Arrayed Large-Area Dust Detectors in INterplanetary space (ALADDIN) is an array of polyvinylidene fluoride (PVDF) based dust detectors aboard the solar power sail demonstrator named IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). The total sensor area of ALADDIN (0.54m2) is the world׳s largest among the past PVDF-based dust detectors. IKAROS was launched in May 2010 and then ALADDIN measured cosmic dust impacts for 16 months while orbiting around between 0.7 and 1.1 AU. The main scientific objective of ALADDIN is to reveal number density of ≥10-μm-sized dust in the zodiacal cloud with much higher time-space resolution than that achieved by any past in-situ measurements. The distribution of ≥10-μm-sized dust can be also observed mainly with the light scattering by optical instruments. This paper gives the scientific objectives, the instrumental description, and the results of microparticle impact calibration of ALADDIN conducted in ground laboratories. For the calibration tests we used Van de Graaf accelerators (VdG), two-stage light gas guns (LGG), and a nano-second pulsed Nd:YAG laser (nsPL). Through these experiments, we obtained depolarization charge signal caused by hypervelocity impacts or laser irradiation using the flight spare of 20-μm-thick PVDF sensor and the electronics box of ALADDIN. In the VdG experiment we accelerated iron, carbon, and silver microparticles at 1–30km/s, while in the LGG experiment we performed to shoot 100׳s-μm-sized particles of soda-lime glass and stainless steel at 3–7km/s as single projectile. For interpolation to ≥10-μm size, we irradiated infrared laser at the energy of 15–20mJ directly onto the PVDF sensor. From the signal analysis, we developed a calibration law for estimation of masses of impacted dust particles. The dynamic range of ALADDIN corresponds from 9×10−14kg to 2×10−10kg (4−56μm in diameter at density of 2.0g/cm3) at the expected impact velocity of 10km/s at 1 AU on the IKAROS inbound orbit. It was found that ALADDIN has ability to measure spatial densities of interplanetary dust particles larger than 10μm in size by setting the sensor threshold to an output voltage of 1V.

Deployment dynamics of a simplified spinning IKAROS solar sail via absolute coordinate based method

The spinning solar sail of large scale has been well developed in recent years. Such a solar sail can be considered as a rigid-flexible multibody system mainly composed of a spinning central rigid hub, a number of flexible thin tethers, sail membranes, and tip masses. A simplified interplanetary kite-craft accelerated by radiation of the Sun (IKAROS) model is established in this study by using the absolute-coordinate-based (ACB) method that combines the natural coordinate formulation (NCF) describing the central rigid hub and the absolute nodal coordinate formulation (ANCF) describing flexible parts. The initial configuration of the system in the second-stage deployment is determined through both dynamic and static analyses. The huge set of stiff equations of system dynamics is solved by using the generalized-alpha method, and thus the deployment dynamics of the system can be well understood.

分離カメラ画像の陰影によるIKAROSの膜面形状推定

IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) is the world's first solar sail demonstration spacecraft. It was launched in May 2010 and has 14-m-square solar sail. Solar sail is a propulsion system which accelerates the spacecraft with the solar radiation pressure, and its performance is largely affected by its unevenness. In order to recover a shape of the sail in the space, pictures of IKAROS taken in the space with cameras separated from the main body are used because of its structural complexity. There are two types of image analysis method and in this paper shape from shading method, in which the brightness of pixels is focused on, is adopted. Since there are some causes of image degradation and they are difficult to model, some cases are verified to know the detail characteristics. This paper presents the approach for analyzing the pictures to obtain the shape of IKAROS sail, and compares the result with the one of another image analysis method and flight data of the attitude motion.

Spinning solar sail orbit steering via spin rate control

The orbit of a solar sail can be controlled by changing the attitude of the spacecraft. In this study, we consider the spinning solar power sail IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun), which is managed by Japan Aerospace Exploration Agency (JAXA). The IKAROS attitude, i.e., the direction of its spin-axis, is nominally controlled by the rhumb-line control method. By utilizing the solar radiation torque, however, we are able to change the direction of the spin-axis by only controlling its spin rate. With this spin rate control, we can also control indirectly the solar sail’s trajectory. The main objective of this study is to construct the orbit control strategy of the solar sail via the spin-rate control method. We evaluate this strategy in terms of its propellant consumption compared to the rhumb-line control method. Finally, we present the actual flight attitude data of IKAROS and the change of its trajectory.

On-orbit verification of fuel-free attitude control system for spinning solar sail utilizing solar radiation pressure

This paper introduces a new attitude control system for a solar sail, which leverages solar radiation pressure. This novel system achieves completely fuel-free and oscillation-free attitude control of a flexible spinning solar sail. This system consists of thin-film-type devices that electrically control their optical parameters such as reflectivity to generate an imbalance in the solar radiation pressure applied to the edge of the sail. By using these devices, minute and continuous control torque can be applied to the sail to realize very stable and fuel-free attitude control of the large and flexible membrane. The control system was implemented as an optional attitude control system for small solar power sail demonstrator named IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). In-orbit attitude control experiments were conducted, and the performance of the controller was successfully verified in comparison with the ground-based analytical performance estimation.

J191063 ソーラー電力セイルで挑む惑星探査([J19106]構造・材料の高度化に向けた宇宙工学と材料力学の展開(6))

Japan Aerospace Exploration Agency (JAXA) successfully achieved the world's first solar power sail technology by IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun) mission in 2010. It demonstrated a photon propulsion and thin film solar power generation during its interplanetary cruise. The 200m2-span sail was deployed and kept extended by centrifugal force of the spacecraft rotation. IKAROS also succeeded in accelerating and controlling the orbit by actively exploiting solar radiation pressure, and thus became the world's first actual solar sailer flying an interplanetary voyage. This paper presents the design of IKAROS solar sail system, operation results and introduces a perspective of this new technology to apply to the next generation mission toward Jupiter and Trojan asteroids.

First Solar Power Sail Demonstration by IKAROS

The Japan Aerospace Exploration Agency (JAXA) will make the world's first solar power sail craft demonstration of photon propulsion and thin film solar power generation during its interplanetary cruise by IKAROS (Interplanetary Kite-craft Accelerated by Radiation Of the Sun). The spacecraft deploys and spans a membrane of 20 meters in diameter taking the advantage of the spin centrifugal force. The spacecraft weighs approximately 310kg, launched together with the agency's Venus Climate Orbiter, AKATSUKI in May 2010. This will be the first actual solar sail flying an interplanetary voyage.

S1901-1-3 小型ソーラーセイル実証機(IKAROS)のセイル展開ミッション(小型宇宙システム(1),社会変革を技術で廻す機械工学)

Japan Aerospace Exploration Agency (JAXA) developed a small demonstrator of solar power sail orbiter to demonstrate solar sail technology that utilizes photons from the sun for continuous acceleration and electrical power generation by thin flexible solar arrays. The small demonstrator "Interplanetary Kite-craft Accelerated by Radiation Of the Sun (IKAROS)" was launched on May 21st 2010, and succeeded in deploying solar power sail on Jun 9th. In this paper, we introduce the deployment mechanism for solar power sail of IKAROS, and report on flight data of sail deployment mission in orbit.

S1903-1-4 小型ソーラーセイル実証機(IKAROS)の膜面展開機構の評価・検証(宇宙構造・材料)

Japan Aerospace Exploration Agency (JAXA) develops a small demonstrator of solar power sail orbiter to demonstrate solar sail technology that utilizes photons from the sun for continuous acceleration and electrical power generation by thin flexible solar arrays. We proceed with "Interplanetary Kite-craft Accelerated by Radiation Of the Sun (IKAROS)" project, which planed to be launched in the summer of 2010. In this paper, we introduce the spread mechanism of solar power sail, and result of various tests or experiments of a proto-type model of IKAROS mission mechanism.