QSAT Mission Analysis and Operation Plan Design

Paper number

IAC-08.B4.3.7

Author

Mr. Alexander Natsuya Uryu, University of Stuttgart, Japan

Coauthor

Prof. Jozef C. van der Ha, Kyushu University, Japan

Coauthor

Prof. Hans-Peter Röser, University of Stuttgart, Germany

Coauthor

Mr. Toshinori Kuwahara, University of Stuttgart, Germany

Year

2008

Abstract

The small satellite QSAT is under development at the Space Systems Dynamics Laboratory of Kyushu University in Fukuoka, Japan. The 3-axis stabilized, 480 mm square, 302 mm height and less than 50 kg spacecraft will be launched in a sun-synchronous orbit to undertake a scientific investigation mission on mechanisms of earth plasma environment and spacecraft charging. Disturbed geomagnetic conditions caused by Field-aligned Currents result in hazardous charging of satellite systems. In order to prevent mission losses it is necessary to understand mechanisms of this phenomenon. A magnetometer developed by the Space Environment Research Center and a High-frequency and a Langmuir Probe, both developed by Kyushu Institute of Technology, are utilized to perform combined measurements. 	
The uniqueness of this mission is the parallel measurements of the geomagnetic field and the electric potential of the satellite, expecting new discoveries on the mechanisms of spacecraft charging.

The present paper deals with the operations concept development for QSAT to guarantee survival of the satellite and accomplishment of the scientific observations during the planned lifetime of one year. Design and operation concept of the QSAT follows the “Faster, Better & Cheaper” philosophy. The latter point is of particular interest for a university project and is mainly realised by the usage of Commercial-of-the-Shelf units. Furthermore, all tasks are conducted by students, considerable on-board autonomy is used and amateur frequency band plus the university owned ground-station is used for communication.	
Specific modes were combined in smooth interaction for every QSAT lifetime phase to ensure reliable and straightforward operability. In line with cost effectiveness and reliability, autonomy is utilised to ease mode transition and data processing. This applies especially in the nominal phase with only about 2 times of 2 successive ground-station accesses per day, separated by 5 or 6 passes of no communication possibility. During the latter autonomy ensures proper mode switching and thus acquirement of mission data and survival of the spacecraft.	
As QSAT uses the amateur frequency band with limited data rate and only one ground-station for downlinking the mission data, it is a challenge to develop an adequate operation plan. Only about 32 minutes of ground-station visibility are available, thus only about 18400 kbit of data can be downlinked per day at a transmission rate of 9600 bits per second. Aiming to meet the mission requirements of obtaining valuable scientific results, especially associated payload mission data, operation procedure is adjusted in “Science Observation Mode”.

Abstract document

IAC-08.B4.3.7.pdf

Manuscript document

IAC-08.B4.3.7.pdf (🔒 authorized access only).

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