$50SAT was developed by Bob Twiggs at Morehead State University (MSU) along with three other radio amateurs and was used to train students.[4] The satellite transmits telemetry data in various operating modes in the 70 cm (28 in) band. It is based on the PocketQube design for very small and inexpensive satellites and measures 5 × 5 × 7.5 cm (2.0 × 2.0 × 3.0 in) (1.5 CubeSat).[5] After several months of problems due to low battery voltage, $50SAT finally dropped below the 3.3 volts required for data transmission on July 19, 2015, and thus ceased operation.[6]
Objective
The objective of $50SAT was to see if a viable satellite could be built to the PocketQube standard.
The sequence of $50SAT transmissions repeats approximately every 75 seconds. An FM slow Morsecall signbeacon, data as fast FM Morse, FSK RTTY data and digital data telemetry.
The slow Morse call sign beacon can be picked up on a hand held UHF receiver when the distance to $50SAT is approximately 800 km or less. The received signal can be improved significantly by using a simple gain antenna such as a BiQuad, Moxon or small Yagi.
The FSK RTTY data has been decoded at up to approximately 2400 km using an omni directional antenna and low noise amplifier.
Digital data telemetry packets (1 kbit/s) from $50SAT can be received with a ground based RFM22B receiver at approximately 750 km using a low noise amplifier and omni directional antenna, with a considerable improvement in reception range when a small yagi is used. The T-LogoQube team have reported that their high gain yagi tracking antenna allowed them to send and receive data telemetry packets at up to 2700 km.
Together with T-LogoQube (Eagle1), QubeScout-S1 and WREN, $50SAT was the first of the new PocketQube standard satellites to be launched.
The primary purpose of $50SAT was to evaluate if PocketQubes would be a cost effective means for engineering and science students to use for developing real world skills.
$50SAT has demonstrated that very low cost satellites are viable in low Earth orbit. The low build cost of $50SAT (less than $250 in parts) means that Engineering models are readily affordable by schools and colleges. The PocketQube chassis has no precision mechanical parts and can be built from locally obtained sheet metal.
The electronics consist of two 40mm square circuit boards. The first is the processor/radio board with the PICAXE 40X2 processor, the Hope RFM22B transceiver module, a temperature sensor, latchup and watchdog protection devices. The second board is the solar power control and monitor board. This board contains the maximum power point controllers as well as current monitors for the battery and summed solar power. The battery is a common 3.7V lithium ion camera battery.
$50SAT was a collaborative education project between Professor Bob Twiggs, Morehead State University and 3 radio amateurs, Howie DeFelice, AB2S, Michael Kirkhart, KD8QBA, and Stuart Robinson, GW7HPW.[3]
Launches are separated by dots ( • ), payloads by commas ( , ), multiple names for the same satellite by slashes ( / ). Crewed flights are underlined. Launch failures are marked with the † sign. Payloads deployed from other spacecraft are (enclosed in parentheses).
