Designing gondola using satcom services and solar cell energy

Introduction of compact, and lightweight terminals for mobile satellite communication, opens up many opportunities to design new telecommunication systems for balloons. Architecture of this gondola, named Narcisse, is built around a control process unit able to support interface with all Inmarsat services, and Iridium or Thuraya satellite network as well. A first technological gondola was launched from Brazil in February 2001, under a Infra Red Mongolfiere (hot air balloon). This gondola used an Inmarsat terminal C which can support in two ways , store and forward messages at a data rate of 600 bits per second. During the 3 turns around the earth, the system worked well, and demonstrated its ability to handle change over from one geostationary spacecraft to the next, when balloon changes ocean region. Moreover this system provides high telemetry rate (Mbits) or telecommand capability, and greatly increase the performances of the scientific payloads . On the other hand, such types of gondola can be useful to operate long duration flight (days) with large stratospheric balloons, currently limited to range capability of UHF ground station . When line of sight of view is lost, between ground station and gondola, the switch would be made from UHF to the Inmarsat or iridium system to complete the mission. In this case, the TM/TC system has no range or altitude limitation, and the gondola descent trajectory can be followed until the ground improving the localization of landing which will be helpful for recovery operation. So, using a real time duplex mini M Inmarsat terminal, the Narcisse gondola has been operationally involved early 2002 in Archeops project. Launched from Kiruna, Narcisse provided a full duplex 2400bits per second link, all along the flight across Russia. Narcisse has been again involved in march 2003 in Mipas project, using Iridium as a cold redundancy to secure Inmarsat mini M not working at extreme polar regions (latitude more than 80°). During this flight an Inmarsat mini M was also used to provide a scientific telemetry and telecomand channel. A lighter version (15 Kg) of this gondola is currently involved in the Hibiscus project (launch of Infrared montgolfieres from Brazil ). This gondola fitted with the new terminal "Ec track" which taking advantage of better RF budget link offered by Inmarsat spacecraft third generation, requires 50% : launch of hundred pressurized balloons from south pole. The target being to decrease the gondola weight to less than 10 Kg. Expecting a life duration of three months, the energy to heat and power the electronic will be only provided from solar cells and Li Ion secondary battery. Plans for the future : Until now all the terminals we have used with Narcisse have a data rate limited to 2400 bit/s. We are now considering to transmit the data from scientific stratospheric balloons gondolas , by using a high speed terminal (64kbit/s) linked to a mechanically pointed antenna under a pressurized radome.