The main mission of the TTÜ100 satellite is Earth observation and demonstration of Earth observation technologies. The satellite includes cameras, image processing and communication with ground-station. For cameras we are using RGB sensor for visual light image and NIR sensor for near-infrared image that can be used for assessing vegetation growth, climate, geology and sea conditions. Image processing on the satellite makes sure that we download only those images that provide valuable information.
Communication with the ground station works on two modes: two-way communication on 435 MHz radio band and one-way data download on 10.5 GHz. 435 MHz is used for telemetry and mission control. 10.5 GHz is used for receiving the Earth observation images made by the satellite. Data download speed is the bottleneck so we need to select the most useful images for downloading. Images that are off-target or have too much cloud cover are neglected.
In addition to Earth observation technology there are scientific experiments: computational fault tolerance and optical communication.
The experiment for fault tolerance of computers is carried out on a reprogrammable FPGA integrated circuit. Different computer hardware configurations can be implemented in this chip. Space is not too friendly to electronics – the radiation from the sun can cause bit-flips in computer memory and processors. It can also be permanently damaging in some cases. The bit-flips happen randomly and can cause false results or even crash the system. The faults need to be found and corrected for electronics to function. We are able to test different computational hardware configurations to determine the more fault-tolerant systems. This experiment also helps to advance microelectronics development on the ground. Today we have reached the level of high integration where the low radiation on the ground already can cause bit-flipping in our most modern computer chips.
|For optical communication experiment LED’s and laser-diodes ar on the satellite to transmit signals. On ground-station we are building a tracking telescope with optical sensors to be able to see the blinking satellite and decode the data. Satellite is able to turn the LED’s and lasers towards ground and transmit test signals. Telescope tracks the motion of the satellite and it is possible to see slow blinking. This way it is possible to send data to ground from our satellite. We are testing – what are the better sensors, how fast can we make the data transfer and at what wavelengths the LED’s or lasers transmit data better through atmosphere. The distance between the satellite and ground-station is 500 km in best case. The most important question that is aimed to answer is – if it is more effective to transmit data through atmosphere with coherent light (lasers) or non-coherent light (LED’s).|
Watch the interview about the TTÜ Mektory Nanosatellite programme with the ISU Program Director Prof. Chris Welch:
Watch the video summary of the TTÜ Mektory Nanosatellite programme Feasibility Study and Preliminary Design Review event with signing of the new partners AS Telegrupp and CGI Estonia.