QB50, an international network of 50 CubeSats for multi-point, in-situ measurements in the lower thermosphere and re-entry research
Jean-Marie Muylaert(1), Ruedeger Reinhard(2), Cem Ozan Asma(1), Jean-Marie Buchlin(1), Patrick Rambaud(1) and Maria Rosaria Vetrano(1)
(1) von Karman Institute, Ch De Waterloo 72, 1640 Rh-St-Genese, Belgium
(2) ESA/ESTEC, Keplerlaan 1, 2200 AG Noordwijk, Netherlands
QB50 has the scientific objective to study in situ the temporal and spatial variations of a number of key parameters in the lower thermosphere with a network of about 50 CubeSats, separated by a few hundred kilometres and carrying identical sensors. It will also study the re-entry process by measuring a number of key parameters during re-entry and by comparing predicted and actual CubeSat trajectories and orbital lifetimes. Space agencies are not pursuing a multi-spacecraft network for in-situ measurements in the lower thermosphere because the cost of a network of 50 satellites built to industrial standards would be extremely high and not justifiable in view of the limited orbital lifetime. No atmospheric network mission for in-situ measurements has been carried out in the past or is planned for the future. A network of satellites for in-situ measurements in the lower thermosphere can only be realised by using very low-cost satellites, and CubeSats are the only realistic option.
For the QB50 network, double CubeSats (10x10x20 cm) are foreseen, with one half providing the usual satellite functions and the other half accommodating a set of identical sensors for lower thermosphere and re-entry research. All 50 CubeSats will be launched together on a single launch vehicle (a Russian Shtil-2.1 or Shtil-2R) into a circular orbit at about 300 km altitude, inclination 79º. The payload mass is about 200 kg (100 kg for the CubeSats, 80 kg for the CubeSat deployment system, 20 kg margin). Due to atmospheric drag the orbits of the CubeSats will decay and progressively lower and lower layers of the thermosphere will be explored, perhaps down to 90 km. The initial orbital altitude will be selected so that the mission lifetime of the individual CubeSats will be about three months. 34 CubeSats are envisaged to be provided by European universities in 19 countries, 11 by universities in the US, 2 by universities in Canada and 3 by Japanese universities. QB50 is planned for launch in mid 2012. By that time, GENSO, the Global Educational Network for Satellite Operations, will be fully operational. It will comprise more than 100 ground stations in different parts of the world, providing nearly continuous uplink and downlink capability for all CubeSats.
The multi-point, in-situ measurements of QB50 will be complementary to the remote-sensing observations of the much larger Earth observation satellites in higher orbits (500-800 km), the in-situ short-duration measurements by experiments on board sounding rockets and the remote-sensing observations from the ground with e.g. lidars. All atmospheric models, and ultimately numerous users of these models, will greatly benefit from the measurements obtained by QB50 in the lower thermosphere.