Nozomi with a prime mission to study the interaction between the solar wind and the Martian upper atmosphere was Japan's first attempt to send an orbiter around another planet. It was launched in July 1998 and the original Mars orbit insertion was scheduled for October 1999. It approached Mars to the distance of about 1000 km in December 2003, but failed to orbit Mars. This paper presents the overview of Nozomi project with a focus on the problems the spacecraft experienced and also the recovery trial which eventually has failed.

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NOZOMI spacecraft was launched on July 4 (JST), 1998 toward Mars. Due to some malfunctions in orbit, NOZOMI unfortunately could not be entered into Martian orbit and expected observation missions around Mars were not performed. However, some autonomous or automatic functions which were prepared to realize the missions were demonstrated ill orbit. This paper describes the autonomous or automatic control functions of NOZOMI AOCS (Attitude and Orbit Control System) and the autonomous imaging function of MIC (Mars Imaging Camera). AOCS autonomous functions were very useful in real in-orbit operation after the telemetry function had lost. The autonomous imaging function of MIC was tested using Moon as a tracking target.

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NOZOMI was the first Japanese mission to Mars. It was launched on 4 July, 1998 (JST) by M-V-3 launcher. The primary scientific objective of NOZOMI was to study the structure and dynamics of Martian upper atmosphere with emphasis on its interaction with the solar wind and 14 scientific instruments were carried on NOZOMI. Due to the malfunction of electronics parts, Mars orbit insertion was abandoned on 9 Dec. 2003 and NOZOMI mission was terminated. However some of the onboard instruments made observations both near the Earth and during cruise phase to Mars. This paper briefly describes the science results obtained by NOZOMI mission.

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NOZOMI spacecraft is the Japanese first mission to Mars, and it was launched in July 1998. After suffering several problems during the operation period of more than five years, It reached near Mars at the end of 2003, However, it was not put into the orbit around Mars. Although NOZOMI was not able to execute its main mission, it provided us a lot of good experiences from the point of the orbit determination of spacecraft. One of the most difficult works was the orbit determination for the period without the telemetry. In this period, for the most of the time the high gain antenna did not point to the earth because of a constraint of the attitude. Therefore the quality of the tracking data was not good, and for some period it was impossible to get the tracking data at all. Under such critical condition, we managed to get the solution of the orbit, and in a miraculous way, we were able to control NOZOMI and execute two earth swingbys successfully. Other issues related to the orbit determination are the spin modulation, the solar radiation pressure, the small force related to the attitude change, and the solar conjunction. We tried to solve these issues by the conventional way using range and Doppler data. However, we also tried the new method, that is the orbit determination by using the Delta-VLBI method (VLBI: Very Long Baseline Interferometry). In addition to this, we tried optical observations of NOZOMI at the earth swingbys.

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