Skip to the timeline
Let's go to Mars

Nozomi takes five years to reach Mars, then flies past

Japan's first interplanetary probe lost the fuel to stop at Mars to a malfunctioning valve in 1998. ISAS flew it five more years anyway, then watched it coast past at 1,000 km.

A full-size spacecraft model with a squat body wrapped in black thermal blanketing, grey instrument boxes and a small square of gold foil on its near face, cone-shaped thruster nozzles below, a mesh dish antenna above it and one gold-framed solar panel on the right. It stands on a low black hexagonal platform in a glass-walled hall, with bare trees and a garden outside, exhibition boards and a chain barrier to the left, and Japanese and English labels at its base reading Mars Exploration "NOZOMI" (PLANET-B).</alt>
A full-scale model of Nozomi, on display at the Sagamihara City Museum. The museum stands directly opposite the JAXA institute that flew the spacecraft from its launch in 1998 until the mission ended in December 2003. · Image: Kestrel

On 14 December 2003 Nozomi passed Mars at about a thousand kilometres and kept going. Five days earlier, controllers at Japan's Institute of Space and Astronautical Science had failed to configure it for orbit insertion; they fired the small attitude thrusters instead, pushing the flyby further out to keep a dead, unsterilised spacecraft off the planet.

Nozomi, "hope", launched as Planet-B on 3 July 1998 on an M-V rocket from the Kagoshima Space Center at Uchinoura: Japan's first planetary spacecraft, and the first mission to Mars from any country other than the United States and the Soviet Union. It weighed 540 kilograms fuelled and carried fourteen instruments massing 33 kilograms in all — magnetometer, ion and electron spectrometers, dust counter, sounder, camera — aimed almost entirely at how the solar wind strips the upper atmosphere off a planet with no global magnetic field to shield it. A thermal plasma analyser would have been Canada's first instrument to orbit another planet.

It looped out to the Moon twice for gravity assists, then made a powered swingby of Earth on 20 December 1998. A valve in the propulsion system malfunctioned, the burn underperformed, and two corrections the next day spent propellant reserved for braking into Mars orbit, ending the October 1999 arrival. The team rebuilt the mission around what was left: four more years in interplanetary space, two further Earth flybys in December 2002 and on 19 June 2003, arrival at Mars at the end of 2003.

On 21 April 2002, inbound for those encounters, powerful solar flares damaged Nozomi's communications and power systems, and a short in the cell running the attitude-control heaters let the hydrazine freeze solid. Contact was lost that May, a beacon reacquired and the fuel eventually thawed, but the mission flew on through a crippled radio and a spacecraft that could not reliably point itself. That is what failed in December 2003.

ISAS ended the mission on 9 December. Nozomi returned interplanetary data on its long detour — dust counts, Lyman-alpha measurements, pictures of the Earth and Moon — and nothing from Mars.