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Romanian Reports in Physics 73, 902 (2021)A PICO-SATELLITE EMBEDDED IN A SODA CANAS AN EDUCATIONAL TOOL FOR ATMOSPHERIC MONITORINGAND TELEMETRY DATA TRANSMISSION THROUGH RFCOMMUNICATIONS. I. TANASE1,2,3*, E. M. BUGA4, L. POIENARIU5, D. TANASE31“Stefan cel Mare” National College, Department of Physics, Suceava 720007, Romania2“Stefan cel Mare” University, MANSiD Research Center, Suceava 720229, Romania3“Spiru Haret” Computer Science National College, Department of Physics,Suceava 720238, Romania4Creative Media and Game Technologies, Saxion University of Applied Sciences,M.H. Tromplaan 287513 AB Enschede, Netherlands5“Stefan cel Mare” University, Faculty of Electrical Engineering&Computer Science,Suceava 720229, Romania*Corresponding authors: tanase sorin2006@yahoo.comReceived February 14, 2020Abstract. Learning activities in which every student engages with hands-onexperiences are considered as a promising classroom activity to motivate youth inscience, technology, engineering and mathematics (STEM) education. One such learningactivities in classrooms which combine physics, engineering, and programming is CanSat.In this paper we present several results concerning the design and production of a picosatellite embedded in the volume and shape of a standard soda can which is capable toperform some of the tasks that artificial satellites carry out after being launched from aplane. The pico-satellite consists of an Arduino Pro-Micro MCU which uses an ATmega32u4MCU, a 9 DOF (degrees of freedom) sensor containing a 3-axis accelerometer, 3-axisgyroscope and a 3-axis magnetometer, pressure and temperature sensors, camera andtransceiver module in order to communicate with the ground station. Details about it,mechanical and electronic subsystems are presented along with the experimentalresults. The correlation between our CanSat design and the properties this device canmeasure could be valuable in the field of STEM education.Key words: Arduino microcontroller, CanSat, STEM education.1. INTRODUCTIONOver the past decade, there has been an increasing demand for new types ofsatellites with different forms, dimensions and improved functional properties susceptiblefor usage in aerospace applications [1–5]. A variety of small satellites capable oftransmitting information in the fields of global warming, earth science, meteorology,atmospheric observation and/or for different space missions have been also proposed[6–11].The CanSat (can-sized satellite) concept was introduced for the first time in1998 by prof. Robert Twiggs with the purpose of motivating children to study

Article no. 902S. I. Tanase, E. M. Buga, L. Poienariu, D. Tanase2Science, Technology, Engineering and Mathematics (STEM) [12–17]. CanSat is asimulation of a real satellite, integrated within the volume and shape of a soft drinkcan [6, 18–24]. The challenge is to fit all the subsystems (e.g. sensors, communicationsystem) in a satellite, labelled CanSat that adopts the dimension of a 350 ml drinkcan. The CanSat is then launched to an altitude of a few hundred meters by a rocketor dropped from a drone, plane and/or balloons and its mission to collect databegins, simulating the development of experiments in space during the descent ofthe CanSat by parachute and finally achieving a safe landing.In a relatively short time the CanSat and CubeSat nano-satellites conceptbecame an important educational tool for university and secondary school studentsto learn and design such satellites and found a wide area of applications in the fieldof aerospace education [25–28]. CanSat offers a great and unique opportunity foryoung students from secondary school to have a first-hand experience of a realspace project; they are responsible for all aspects ranging from designing and buildingthe CanSat to selecting its mission, integrating all the components in a soda can,testing, preparing for launch, the mission itself and then analysing the data.Much attention was given in the last years to the use of computers [29, 30],tablets or/and phone in physics education as supplements or even as substitutes forconventional experimental materials and it was revelead that students can carry outtheir own measurements of authentic physical data with their own smart device[31–37]. To encourage student engagement and motivation, it is recommended tocombin methods, procedures and materials by assessing physics and engineeringconcepts with new technologies. It was demonstrated [31–37] that such combinedmethods and learning activities during the classroom provide how youth canintegrate electronics (e.g. sensors, microcontroller) and learns to design a complexprogrammable circuit with creativity and fun.In this study we report on the design, process of assembling and testing of apico-satellite embedded in the volume and shape of a standard 350 ml soda can.The pico-satellite was designed to measure some physical parameters such astemperature, atmospheric air pressure, magnetic induction of the earth and telemetrydata (e.g. data concerning its position, acceleration, taking photos for analyzing theterrain from above) through radio frequency (RF) communication after beinglaunched from a plane at an altitude of approximately 1000 m. The engineering,physical concepts and theory underlying the CanSat can be explored withouthaving much in-depth knowledge of this subject.2. EXPERIMENTAL DETAILS2.1. CANSAT REQUIREMENTSThe pico-satellite was set according to our previous paper [38] and wasmanufactured under the CanSat competition guidelines [18, 28]. It encompassesdifferent rounds ranging from building the CanSat, integrating the components and

3A pico-satellite embedded in a soda canArticle no. 902sensors, programming the software, testing all the systems, preparing for the launchcampaign and finally data analyses.2.2. CANSAT DESIGNThe pico-satellite consists of five subsystems, each of them connected on a printedcircuit board (PCB), where all electronic components are assembled and soldered asfollows:(1) CanSat kit [39] containing an Arduino Pro Micro microcontroller (Fig. 1),RFM69HW 433 MHz transceiver and BMP180 temperature and barometric pressuresensor.Fig. 1 – Arduino Pro Micro microcontroller used to develop the CanSat (a)and block diagram of Arduino Pro Micro microcontroller used to develop the CanSat (b) [39].

Article no. 902S. I. Tanase, E. M. Buga, L. Poienariu, D. Tanase4Details about the CanSat kit specifications and sensors employed to developour pico-satellite are given in Table 1 and information about operating conditions,output signal and mechanical characteristics for the BMP180 temperature andpressure sensor are shown in Table 2.Table 1CanSat kit specification [39]MicrocontrollerCommunicationSensorsArduino Pro Micro microcontroller Clock speed: 16MHz 2kb of RAM and 16kb of flash memory I2C, SPI and UART serial communication ports; 9 10-bit ADC pins 12 Digital I/Os (5 are PWM capable)RFM69HW 433 MHz transceiver Frequency: selectable by software over 256 different channels Modulations: FSK, GFSK, MSK, GMSK, OOK 128 bit AES encryption Programmable output power: –18 to 20 dBm in 1 dB steps RF power: 100 mW Sensitivity: –120 dBm at 1.2 kbps SPI InterfacesBMP180 temperature and barometric pressure Logic: 3 to 5V compliant Pressure sensing range: 300–1100 hPa (9000 m to –500 m abovesea level) Up to 0.03hPa / 0.25m resolution – 40 to 85 C operational range, /–2 C temperature accuracy I2C interfaceTable 2Operating conditions, output signal and mechanical characteristics for the BMP180 temperatureand barometric pressure sensorParameterSymbolOperating temperatureTASupply voltageVDDSupply current@ 1 sample/sec25 l accuracyripple max. 50mVpp–4001.81.62ultra low power modestandard modehigh resolution modeultra high resolution modeTyp2.52.535712Max 85 653.63.6Units CVμAμAμAμA

5A pico-satellite embedded in a soda canArticle no. 902(2) Mission subsystem containing an AltIMU-10 v4 module: LPS25H pressureand temperature sensor, L3GD20H gyroscope, LSM303D accelerometer and LSM303Dmagnetometer.(3) Power subsystem: 2000 mAh 18650 lithium-ion battery together with a5V step-up converter was used as a power supply for all the system.(4) Recovery system & camera: for establishing the position of the picosatellite during its free fall, but also for recovering it if it will be lost, we shall usethe Sparkfun Venus GPS module that will give us the longitude and latitude of thesatellite; the module has a 20 Hz refresh rate and a 2.5 meters margin of error,making it ideal for our work. Also, TTL Serial JPEG Camera with a resolution of640 480 was mounted for taking photos.(5) Communication subsystem and ground station consists of a radio RFM69transceiver to provide long range communication capabilities. The frequency thatwe are going to use for data transmission/reception between our CanSat and theground station is 434 MHz (license free band in Romania). The CoolTerm softwarewas employed to record the serial data sent to the ground station on a text file forlater use in our graphing software, it provides a friendly interface without theproblems other serial-recording software seemed to have.All PCBs are connected and joined each other by means of pin-connectorsinstead of electrical wires to conform the integration in a 350 ml drink can. Theblock diagram of the CanSat is presented in Fig. 2.Fig. 2 – The block diagram of the CanSat (a) and the ground station (b)designed to measure some physics parameters and telemetry data through RF communication.In order to achieve a slow descent of the pico-satellite a parachute wasmounted out-side the soda can (Figs. 3, 4). The parachute was made with a circulargeometry (50 cm diameter). In order to provide vertical stability during the descenta 5 cm circular hole was made in the centre of the parachute.

Article no. 902S. I. Tanase, E. M. Buga, L. Poienariu, D. TanaseFig. 3 – Pico-satellite embedded in the volume and shape of a standard soda can(height: 115 mm, diameter: 66 mm).Fig. 4 – Pico-satellite embedded in the volume and shape of a standard soda canbefore the launch from the plane (Romanian CanSat competition).6

7A pico-satellite embedded in a soda canArticle no. 9023. RESULTS AND DISCUSSIONSIn order to verify the functionality of the pico-satellite, to confirm the datatransmission through RF communication and to verify the deployment of theparachutes a series of tests were made. In Fig. 5 the results obtained duringlaboratory tests of BMP180 sensor are presented.Fig. 5 – Temperature recording with the BMP180 sensor (a), signal strength (b) and screenshotof the Arduino software debug protocol during laboratory tests (c).Communication subsystem and ground station consists of a radio RFM69transceiver to provide long range communication capabilities. Using this type ofreceiver we ensure over 400 meters range when using whip antennas and a severalkm range when using a Moxon antenna (Fig. 6) on the receiving, while connectedto a notebook. In Fig. 7 we present the results during the calibration tests of Moxonantenna.

Article no. 902S. I. Tanase, E. M. Buga, L. Poienariu, D. Tanase8Fig. 6 – Moxon antenna design calculator generated with http://w4.vp9kf.com/moxon calculate.php (a)and Moxona antenna used during measurments (b).After the laboratory test, the CanSat was launched from a drone at analtitude of approximately 80 m in order to verify the deployment of the parachute.During the descent the total mass (m 0.300 kg) of the pico-satellite and theparachute exerted a force (Fig. 8), proportional to the square of velocity. The forceand the velocity were calculated using the following equations (1, 2) [25, 40, 41]Fd v 1 v 2 cd S2(1)2 m g, S cd(2)