The Quasi-Zenith Satellite System (QZSS) is a Japanese satellite navigation program planning for a future evolution to the regional satellite navigation system in East Asia and Oceania. A two stage system deployment is planned. In the first step, is the launch of a single satellite (QZS-1) in 2009 for technical validation and application demonstration. The second step involves the launch of the second and third satellites several years later to demonstrate full system operation. JAXA and related research institutes are in charge of technology development and demonstration of GPS complement and augmentation from QZSS.

QZSS is a three satellites constellation where each satellite is placed in the different orbital planes with inclined, geo-synchronous period and slight eccentricity. Each satellite is allocated in an orbit so as to pass over the same ground track at constant intervals with at least one satellite in place near zenith over Japan. QZS-1 will be launched by H-IIA launch vehicle from Tanegashima Space Center in Japan; the target launch year is 2009.

The QZSS has complete interoperability with GPS and will be worked as a GPS satellite with better geometrical position. QZS will improve availability and DOP compared with use of GPS only, especially in urban canyon and mountainous terrain. The satellite system is also a good platform for WDGPS (Wide-area Differential Global Positioning System). High elevation angle characteristics can be applied to the WDGPS platform for stable link.

QZS-1 precise orbit ephemeris will be transmitted through the QZS-1 Navigation Message in the same way as is currently done in GPS. JAXA will perform QZS-1 precise orbit determination using L-band Navigation data received at monitor stations. The target accuracy of SIS-URE (radial direction) is several tens centimeters. SLR of QZS-1 is necessary to estimate navigation data biases and evaluate orbit determination accuracy.

Mission Instrumentation:

QZS-1 has the following scientific instruments:

Radiation Cooled TWT
Laser Reflector
C-band TTC, L1-SAIF, L-band Helical Array, and TWSTFT Antennas

QZS-1 Mission Parameters:

QZS-1 Mission Parameters
Sponsor:	JAXA
Expected Life:	12 years
Primary Applications:	Technology demonstration Satellite navigation
Primary SLR Applications:	Calibration of GPS orbits
COSPAR ID:	TBD
SIC Code:	TBD
NORAD SSC Code:	TBD
Launch Date:	2009
NP Bin Size:	5 minutes
RRA Diameter:	1.6"
RRA Shape:	Planar
Reflectors:	36 corner cubes
Altitude:	32,000-40,000 km
Inclination:	45 degrees
Eccentricity:	0.099

Additional Information:

Web sites:

Publications:

M. Sawabe, S. Nakamura, Request for QZS-1 SLR Tracking at Missions Working Group Meeting, 15th International Workshop on Laser Ranging, October 2006