PPT Development for Nanosatellite Applications: Experimental Results
In this paper, the design and performances of a pulsed plasma thruster (PPT) for nanosatellite applications will be presented. The breadboard model PPT presented in this paper will be a part of six PPTs propulsion system designed to provide attitude and translational control for a 20-kg nanosatellite for a total delta-V of 40 m/s. The thruster performances have been characterized in terms of electrical parameters, mass bit, impulse bit, and specific impulse. The thruster was found to be compliant with the mission requirement. Moreover, preliminary electromagnetic noise interference measurements have been performed. The spark plug discharge was found to be the main source of noise as already found by previous authors. From the collected data, it can be inferred that the noise is mostly radiated.
The Design of a Lunar Farside Gravity Mapping Nanosatellite for the European Student Moon Orbiter Mission
The construction of a high-resolution map of the lunar gravity field would be very useful for studies of the lunar interior, and would be invaluable for accurately planning future lunar orbiter missions. Previous gravity-mapping missions have tracked the gravitational perturbations of lunar satellite orbits from Earth to construct nearside gravity maps, but have only been able to provide extrapolated measurements of the far side gravity field due to the lack of tracking data while the satellite's orbit is occluded by the Moon. Gravity-mapping payloads utilizing satellite-tosatellite range-rate tracking between a pair of lunar orbiters have been proposed on previous lunar missions, but have not yet flown. The University of Toronto Space Flight Laboratory, using expertise and design heritage from the CanX nanosatellite program, is in the process of developing a payload for the European Student Moon Orbiter (ESMO) called “Lunette,” a gravity-mapping nanosatellite that will separate from a parent spacecraft and fly along track in a 100 km altitude circular polar lunar orbit. The Lunette nanosatellite is based on SFL’s Generic Nanosatellite Bus and includes a coherent S-band radio transponder, three-axis attitude determination and control, and a 100 m/s propulsion system, allowing it to maintain an along-track orbital formation and measure the rangerate between itself and the parent spacecraft using Doppler tracking. These range-rate measurements will be used to construct a full-sphere lunar gravity map with an accuracy of 20 mGal or better, comparable to the current bestaccuracy nearside gravity map from the Lunar Prospector mission data. Lunette has been selected as a payload for the ESMO project under the Student Space Exploration and Technology Initiative (SSETI) program of the European Space Agency. ESMO is currently in Phase A study, and is targeting a launch in 2011.
First Insights into the Draft Genome Sequence of the Endophyte Paenibacillus amylolyticus Strain GM1FR, Isolated from Festuca rubra L.
ABSTRACT Paenibacillus amylolyticus strain GM1FR is an endophyte isolated from aerial plant tissues of Festuca rubra L. Here, we report the draft genome sequence (7.3 Mb) of GM1FR containing 6,241 protein-coding genes, some of which are potentially involved in plant growth promotion and biocontrol.