collage-sat

The aim of this project was to generate a conceptual idea for turning an android or ubunto (linux based) smartphone device into a low orbit micro satellite. The satellite must utilise the phones processing as well as features such as the camera for capturing required data. Team Duct Tape took this project as three core elements, the hardware of the smartphone satellite as a unit, the software to run the unit, and what the phone will be doing, for example the Star Tracker App stated in the challenge. We focused mainly on the hardware aspect of this project and with collaboration with other teams hope to have a full, successful concept solution.

The smartphone satellite was broken down into three main areas, power supply, communication, and attitude control. It was decided the smartphone battery and additional solar panels will be used for the main power supply. It was calculated approximately 2x the required power will be generated by the solar panels chosen alone. The solar panels will be connected to the smartphone via the smartphones usb port. Initially the solar panels will be inside the satellite, similar to existing cubeSATs. Once in space, the solar panels will deploy and begin generating power. The smaller solar panels will have the low gain antenna attached for communication with earth.

For communication with earth the smartphone is connected to a radio transceiver through the headphone jack. The headphone jack has two outputs and one input. It will be only the ‘left ear’ output and ‘mic’ input parts of the headphone jack connected to the radio frequency transmitter. The transmitter is then connected to a low gain antenna (extending out from the satellite) which can then transmit either directly to ground base or to ground base via other satellites such as the Tracking and Data Relay Satellite (TDRS) system. Data sent to ground base must be encoded into to be sent as radio waves, this will be done using frequency shift keying. A 315MHz Transmitter can reach data speeds of 10Kb per second, this means in a 10 min pass, up to 6 Mb of data can be transmitted. Photos and other data will be compressed using traditional data compression.

Attitude control will be achieved using an arduino and a gyroscope connected to the smartphone. The arduino will receive orientation instructions from earth via the smartphone and then using the gyroscope can correctly position itself so the camera can take quality images. The arduino will be connected to the smartphone via the ‘right ear’ headphone jack output. A prototype was constructed to illustrate how this would work, however, due to a lack of resources, diodes were used to represent the motors and a potentiometer as a gyroscope. Turning the potentiometer (gyroscope) would tell the arduino it is moving, then the correct motors will turn on, causing the satellite to move into the right position. Once in the right position the motors can stop moving, if the satellite 'overshoots' its required position, the motors will turn in the opposite direction and repetition of this process will cause the satellite to maintain in the right position. The arduino code used can be found in the Google drive folder attachment below (Note, sign in to any google account to view document).

Due to the designs smaller profile, (10cm x 10cm x 4cm) 15 of these satellites will be able to fit in a normal 3 pod payload designed for normal cubeSATs. It was designed that the smartphone satellite has the same height and width as normal cubeSATs so existing launch methods can be used. The thickness has been greatly decreased with the smartphone addition. Due to the smaller profile and use of commercially available parts, the estimated cost of a smartphone satellite including launch is $10,000 (NZ). This is a substantially cheaper alternative to larger satellites.

In addition, due to the decreased cost of a smartphone satellite, space will be opened up to more people, with schools, universities and communities now able to launch their own satellite. This leads to a number of future applications where more people can be inspired by and involved with space.

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