GAMASAT 1 (QB50 PT01)

GAMASAT 1 [University of Porto]

GAMASAT 1 is a 3U-CubeSat for technology development and upper atmosphere science. It is developed and built at the Faculty of Engineering of the University of Porto in coperation with TEKEVER.

It is a part of the QB50 constellation to gather science data in the upper layers of the troposphere in the altitude range from 350 km down to 200 km. The QB50 project, which demonstrates the possibility of launching a network of 50 CubeSats built by Universities Teams all over the world to perform first-class science in the largely unexplored lower thermosphere.

It carries the FIPEX (Flux-Φ-Probe Experiment) of TU Dresden as the primary payload for the QB50 project, which is able to distinguish and measure the time-resolved behaviour of atomic and molecular oxygen as a key parameter of the lower thermosphere.

Apart from this cooperation with the QB50 scientific goals, GAMASAT will have three technological objectives:

• GAMANET is an ambitious endeavour in space communications. Its challenge is the creation of the largest ad hoc communications network ever in Space. Its goal is to bring the networking capability to satellite constellations. As GAMANET participants, CubeSat Teams will have the networking resources required to send commands from Ground and to receive satellite telemetry, even when their own satellites are not within range of their Stations. Joining CubeSats and Ground Stations in a seamless communications network, the GAMANET initiative aims to 1) validate innovative communication technologies in space and 2) improve the overall QB50 communications and scientific results. GAMANET’s enabling device is GAMALINK, an advanced communications platform relying on the flexibility of Software-Defined Radio. Present on every GAMANET node, whether a CubeSat or a Ground Station, GAMALINK empowers the formation of mobile wireless ad hoc networks in space. GAMALINK also delivers accurate position determination based on GPS, which provides absolute position and timing information that may be used to achieve synchronisation between satellites.
• Radio-based attitude determination: GAMASAT proposes to develop a novel attitude determination experiment based on radio waves. Radio signals in the S-band region of the spectrum will be sent from three patch antennas on each face of the CubeSat, allowing the receiver(s), either ground stations or other GAMALINK enabled satellites, to measure the carrier phase difference between antennas. These differences are geometrically related to the relative attitude of the satellite to the observer. Between these antennas and the driving RF front-end there will be antenna switch electronics, allowing one RF front-end in the GAMALINK board to synchronously switch between antennas and generate the required attitude dependent signals in space. Besides coding to avoid interference with other radio sources, the signals transmitted will carry basic telemetry of GAMASAT. The bandwidth of these signals will fit 15 KHz, enabling reception at a ground station to be achieved through conventional equipment (an S-band dish antenna on a rotator, a radio receiver and a computer with an audio card). This will enable this mode of operation to act as a beacon, which can be received by amateur radio stations across the globe.
• Q-RED is a controlled de-orbiting and re-entry experiment. It will adjust the ballistic coefficient of the 3U CubeSat in order to adjust the re-entry point of the satellite, by periodically changing the attitude of the satellite relative to the apparent wind. In its nominal attitude, the satellite will fly with the smaller face associated to the scientific payload facing the flight direction. Between the altitudes of 120 km and 250 km, the satellite will be periodically rotated by 90 degrees in order to expose one of the larger faces, decreasing the ballistic coefficient by a factor of 3, in a duty cycle that will be controlled using feedback from navigation. Such rotation will be performed by the three reaction wheels, which are able to turn the satellite in a few seconds. Upon reaching an altitude of 120 km, a small re-entry capsule will be ejected. Such capsule is made of several layers of ablative and non-ablative heat-resisting material and contains a battery, micro-controller, temperature, acceleration and rotation rate sensors, a SDR transmitter capable of sending ARGOS messages, a GPS receiver and a passive oscillation dumper.

The satellite will be launched with the bulk of the QB50 constellation to the ISS in 2017, from where they will be deployed. The in-orbit lifetime of nSIGHT 1 is about 3 months, from deployment to de-orbit.