Inter-Satellite Link System Design and Simulator for JAXA Magnetotail Exploration Missions

Paper number

IAC-07-B2.2.05

Author

Dr. Tomoaki Toda, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan

Coauthor

Ms. Sachiko Houzawa, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Dr. Yuichi Tsuda, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Dr. Yoshifumi Saito, Japan Aerospace Exploration Agency (JAXA), Japan

Coauthor

Dr. Iku Shinohara, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan

Coauthor

Prof. Masaki Fujimoto, Japan Aerospace Exploration Agency (JAXA)/ISAS, Japan

Year

2007

Abstract

It’s a common knowledge that formation flight technologies offer a suitable method to study dynamic behaviors of plasma distributed around Earth. The JAXA’s next mission to explore the magnetospheric region is also designed to make the most use of formation flight benefits. Its inter-satellite links need data transfer and ranging measurement in a more intensive manner than ever missions. Based on the autonomous closer connection among satellites than that between satellites and ground stations, the mission aims to reveal microscopic dynamical phenomena in the magnetotail. We have studied a S-band burst communication system as one applied to such a mission. 
  In our plan, plural satellites, for instance, more than 5 satellites take part in the magnetotail observation campaign during the mission. It is normal that the resource allocation for each satellite is strictly limited in such a mission assuming a simultaneous launch of satellites. Therefore, a simple switchable low gain antenna system to cover a wide area of sight of satellites was assumed to design necessary inter-satellite links. Additionally, we place one larger satellite at the center of formation as a mother satellite to control the other daughter satellites. Within this frame, we discuss our future inter-satellite onboard communication system.
  We have proposed S-band TDM/TDMA network system enabling data exchange and ranging operation among the satellites. This system relies on only one S-band channel and avoids us from a difficult task to coordinate larger bandwidth for the mission. Our primary target to apply this system is the mission named as SCOPE (cross Scale COupling in the Plasma universE). For this mission our system permits the data transfer from daughters to the mother up to 250kbps within the mutual distance of 100km and ranging operation of 1meter accuracy from the mother, clock synchronization less than a microsecond error among satellites, and optional range measurement among daughter satellites to improve formation estimation error in the orbit. Naturally the above inter-satellite link system is designed as a part of total communication system including continuous links from and toward ground stations. 
  We have developed a breadboard model to verify above inter-satellite communication scheme, where the initial inter-satellite link and following constant periodical burst link establishment become important depending on particular mission conditions. The initial test results were as designed for SCOPE and showed an even higher performance in ranging and clock synchronization function.

Abstract document

IAC-07-B2.2.05.pdf