Japan's Nozomi Mars probe launched in 1998

Japan's Nozomi Mars probe, launched on July 4, 1998, from the Kagoshima Space Center aboard a M-V rocket, faced multiple challenges during its five-year journey. Originally named Planet-B before launch, the probe was developed by the Institute of Space and Astronautical Science (ISAS) in collaboration with the University of Tokyo.

Nozomi's mission and technical details

Its objective was to study the Martian atmosphere, particularly its upper atmosphere, and to understand how the solar wind erodes it over time. The probe had a dry weight of 258 kilograms and 282 kilograms of propellants.

Initial flight plan and propulsion issues

The flight plan included two lunar flybys on August 24 and December 8, 1998, followed by a powered flyby near Earth on December 20, 1998, at approximately 1,000 kilometers altitude. This maneuver was intended to provide the necessary momentum to reach Mars as early as October 1999. However, a defective thrust valve led to insufficient thrust, and two trajectory corrections made the following day further worsened the fuel deficit.

Mission redesign and solar flare damage

The planned arrival on October 11, 1999, was canceled, and the mission had to be redesigned, requiring four additional years in heliocentric orbit and two new Earth flybys. A significant turning point occurred on April 21, 2002, when powerful solar flares struck Nozomi, damaging its communication and power systems.

Communication loss and recovery attempts

A short circuit occurred in a cell responsible for controlling the heating of the attitude control system, causing the hydrazine fuel, essential for orienting the probe, to freeze. Contact was lost on May 15, 2002. After two months of searching, ISAS teams rediscovered the probe's beacon, but the situation remained critical: the spacecraft was drifting, half blind, with a partially non-functional propulsion system.

Efforts to thaw frozen fuel

Engineers attempted to use natural warming as the probe approached Earth to thaw the frozen fuel. Two rescue Earth flybys, on December 21, 2002, at approximately 29,510 kilometers and June 19, 2003, at approximately 11,023 kilometers, allowed the frozen fuel to thaw. However, the systems damaged by the solar flares were not fully recovered.

Nozomi's final approach to Mars

On December 9, 2003, Nozomi finally approached Mars, five years after its departure. Orbital insertion was scheduled for December 14. However, attempts to orient the spacecraft correctly failed due to weakened electrical systems. The ISAS decided to fire the remaining small thrusters on December 9 to increase the closest approach distance to 1,000 kilometers to avoid an uncontrolled crash on the Martian surface, which could have caused potential biological contamination.

Nozomi's uncontrolled drift

On December 14, 2003, Nozomi passed near Mars without entering orbit and drifted back into space on a heliocentric trajectory of about two years. The mission cost approximately 20 billion yen, or around 186 million dollars. The economic newspaper Nihon Keizai Shimbun estimated the chances of success close to zero long before the official announcement of the mission's abandonment.

Japan's new Mars mission with MMX

Twenty-eight years after Nozomi's failed attempt, Japan is preparing to try again with the MMX probe. The Japan Aerospace Exploration Agency (JAXA) has confirmed the launch of the MMX probe on an H3 flight, with an initial launch date aimed for October 20, 2026, at 4:41 local time, with a contingency period extending until November 7.

MMX's mission to Phobos

This time, the target is not Mars itself but its moon Phobos, where the probe must collect at least 10 grams of material before returning them to Earth in 2031.