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SPROUT



    【1.Verification of design methods and the space demonstration of deploying of the inflatable membrane structure】
    (1)Deploying demonstration of the inflatable membrane structure
    The SPROUT is going to deploy the inflatable tubes and the equilateral triangle (one side is about 1500[mm]) membrane by injecting N2 gas to the tubes. The inflatable membrane structure is expected to building next era of the space craft technology such as the Photovoltaic Power Satellite or the Solar Sail. However, these have not demonstrated enough yet. Therefore, the SPROUT can make an opportunity (although the small size) of the realization for the spacecrafts by demonstrating by the SPROUT. In particular, while the Small Solar Power Sail Demonstrator IKAROS has succeeded in 2010 and the extension / expansion experiment SIMPLE of the inflatable structure in the JEM’s exposed section at HTV-3 had launched in the summer of 2012, the space demonstration of the inflatable membrane structure by the SPROUT will provide an important achievement that Japan keep the top spot in the world in this field. (Fig: Reprinted from JAXA digital archive)
    (2)Demonstration of the design methods of the inflatable membrane structure
    We are going to conduct validation of the design of the inflatable membrane structure and the deployment mechanism by the quantitative comparison with the data of numerical analysis and data during deploy the inflatable membrane. From the results of the deployment experiment of the ground, the inflatable tubes adopt the “Fold octagon”, the membrane adopts the “Fold Miura”. The validation methods of the design is two types. Firstly, we are going to be validated that history data of the gyro is consistent with an error less than 90% of the data analysis by using analysis software which is originally developed the “NEDA”. Secondly, three-dimensional coordinate data of the feature points of the membrane that is obtained from the stereo image by two mounted camera is consistent with an error of less than [TBD]% with data analysis. Deployment sequence can be divided two types, first stage (quasi-static) and second stage (dynamical).

    The first stage, cutting the string with thermal cutting by sending current through the nichrome wire, then, the lid will be released. After deployment, the inflatable membrane deploys slowly from the storage mechanism by the restoring force of the fold of the tube and the membrane. The second stage, inject the gas into inflatable tube for deploying. The deployment in the space plans the end of January in 2015.










    【2.Demonstration of the attitude determination and control technology of nano-satellite】
    Attitude determination experiment using the sun sensors, gyros sensors, magnetic sensors, and, to perform attitude control experiments with magnetic torquers, shows the attitude determination and control possible level nano-satellite. We will make the attitude control experiment using the magnetic torquers and attitude determination experiment using the inexpensive sun sensors, gyros sensors, magnetic sensors. In the SPROUT, emphasis is put on itself that the accuracy of attitude determination and control is shown from the data on an orbit, rather than aiming at highly precise attitude determination and control. Some nano-satellites equipped with attitude determination and control system already has launched, but it is hard to say that not necessarily sufficient success or technology assessment on an orbit has been performed. By repeating attitude determination and control experiment by the SPROUT, we can estimate quantitatively how far nano-satellite equipped with inexpensive and simple hardware can perform attitude determination and control. We expect that the attempt will be a precious achievement for nano-satellites of future.








    【3. Prediction of orbit descent rate change by the inflatable membrane structure】
    The SPROUT not only deploys the membrane but also it aims at orbital descent of a satellite by increasing air resistance by deployment membrane. The satellite whose weight a size is 1[kg] in 10[cm³] will take tens year, before an orbital descent is completed. But the SPROUT will be able to complete an orbital descent in several years by deploying a big membrane to the satellite. We consider the problem of the space debris which has become the center of attention recently, and we demonstrate and propose the design methods of non-debris of the nano-satellite. Therefore, we consider that it is able to promote the space experiment of nano-satellites in the future. (Figure: Reprinted from NASAHP)
    ) About the prediction method, we compare the orbital altitude that is simulated over a long time by the orbital predictive simulation in consideration of the increase in the atmospheric resistance by deployment of the inflatable membrane structure, and the actual orbital altitude of the SPROUT that is measured. By it being shown that it is agreement with an actual orbital altitude within error [TBD] %, the simulation result shows the validity of the simulation. About predictive accuracy, we accumulated the orbital element of the SPROUT which is offered by NORAD (North American Aerospace Defense Command) for five years, and we compute by comparing with the simulation result the orbital altitude for which it offered from there.





    【4. Operation of satellite by a ham radio operator】
    The ham radio missions are missions performed for the improvement in the ham radio technical of Nihon University to accumulate, after finishing engineering missions. We are going to exhibit the ground station software which is possible to uplink by a ham radio operators, and it is considered that we would like you to use as one of the places of the improvement in the radio technology. We would like to train our radio communications technology by carrying out technical exchange with the ham radio operator through this line. Specifically, we would like to perform the following five missions.

    • 1.Degi-talker
      Digitalker is the function which repeats voice mail messages from the satellite and transmits on the ground. In the SPROUT, the sound recorded on the ground beforehand is recorded on the IC called "Digitalker". And the recorded sound is transmitted from on an orbit to the ham radio station on the ground using FM transmitter. We think that it will carry out for making it the contents in accordance with the radio law.

    • 2.SSTV
      The SSTV is the function which transmits a still picture in color on the ground from a satellite using The SSTV (Slow Scan TeleVision). In the SPROUT, the picture that is mounted beforehand is changed into a SSTV signal, and it transmits to the ham radio station on the ground using FM transmitter. The send mode is set the picture size per sheet to 320 pixel × 256 pixel by Scotti1.

    • 3.Voice message box (recording + playback)
      The voice message box is the function to relay the data under voice transmitted from the ham radio station on the ground. When voice data is uplinked to the SPROUT, the SPROUT saves the uplinked voice data at the digitalker. And the voice data that is saved is transmitted by using FM transmitter in the SPROUT to the ham radio station on the ground.

    • 4.Text message box (text transmitting + text output)
      The message box is the function to relay the text data transmitted from the ham radio station on the ground. When the text data that is uplinked to the SPROUT, the SPROUT saves the uplinked text data. And, the text data that is saved is transmitted with FM packet (1200 bps) to the ham radio station on the ground . Now, the number of characters which can transmit is planning a maximum of 44 characters.

    • 5.Earth mapping project
      The project which will make the earth takes the photo of the earth using the camera that is carried in the SPROUT, and it classifies for the place of every photo, and enables it to watch on this homepage. In this homepage, we would like to also put the photograph taken and contributed not only on the photos of the earth in Nihon University but on ham radio operators. Please contribute "the photograph which carried out the downlink", and "the uplinked command" to the specially set-up page of the project. We specify the orbital coordinates which took a photo in Nihon University, and put on the homepage. Presently, we consider the following four patterns about the photography method of the earth.

    In the case of taking photo of the earth, we can choose the following four modes. Every mode takes a maximum of six photos, and performs the downlink of the picture by the SSTV.

    • Time specification photography mode (engineering missions camera and outreach missions camera)
      A shutter is pushed with the signal from a data-processing system.
    • ADC shutter mode (outreach missions camera)
      A shutter will be pushed if it judges that the camera turned to the direction of the earth from the solar sensor data of the ADC.
    • Attitude determination photography mode (outreach missions camera)
      Attitude determination is performed from the sun sensors, magnetic sensor, and gyro sensors data of the ADC and a shutter will be pushed if it judges that the camera turned to the direction of the earth.
    • Attitude control photography mode (outreach missions camera)
      The SPROUT is controlled by the magnetic torquers of the ADC, and a shutter will be pushed if it judges that the camera turned to the direction of the earth.












    【5.Local exchange activities】
    The first Satellite launched at April 2013. We offer amateur radio service which make an opportunity to hearing record voice form the satellite. This voice was recoded form the neighborhood school children. Also this service makes experience of using amateur radio wave with operators form all over the We planed "Let's send massage to the space." campaign which makes micro film collected from public. These micro films sent to space with our satellite. We got 800 massages form 1500 public peoples. We might make many peoples to feeling space familiar form these campaigns. We also plan some services to make space familiar at next satellite SPORUT. For example, we also planed micro film massage campaign and to hold a outreach activity to makes peoples space familiar. Now we are inviting massages. So if you have same massages to want to send space. Please send us.