Nozomi has been flying for five years and has already missed Mars once. It carries a Canadian-built instrument that would measure the gases in Mars' thin atmosphere. Nozomi is designed to orbit Mars.

But Japan acknowledges it can barely control Nozomi, and the spacecraft may crash on Mars within a few weeks, or miss the planet and drift aimlessly around the sun forever.

Nozomi means "Hope," and the little spacecraft could use some.

It has experienced a series of failures that kept it from reaching Mars on its first trip. Unfazed, its operators swung it around for a second pass at the Red Planet, but now say the probe is in its "final challenge" and may never arrive.

Translation: Nozomi, and the Canadian-built Thermal Plasma Analyzer, may continue a tradition of man-made probes that don't survive the trip to the bad-luck planet.

Canada's instrument is the country's first participation in a mission to another planet. In theory, once Mars orbit is established, the Thermal Plasma Analyzer will be extended out from the satellite on a boom, and its measurements of the Martian atmosphere will begin.

It is designed to measure low-energy particles and gases considered vital to the understanding of the origin and composition of the Martian atmosphere. Other instruments will study the magnetic field of Mars and take pictures of the planet's surface.

The Canadian Space Agency is funding this research. It involves scientists from the University of Calgary (the co-Principal Investigators of the TPA are Dr. Andrew Yau and Dr. Greg Garbe, professors of physics and astronomy at the University of Calgary), as well as scientists from the Universities of Alberta, Western Ontario, and Victoria. Others on the research team include scientists from Hokkaido, Nagoya and Tokyo.

Nozomi's troubles began in December 1998 during an Earth fly-by that was to "slingshot" the craft toward Mars, and arrive there in October 1999.

But the plan went wrong. A stuck valve forced controllers to do extra manoeuvres, leaving Nozomi too low on fuel to steer safely into orbit around Mars at the scheduled arrival time.

The Nozomi team was forced to steer a more indirect path, and the probe is now closing in on Mars, and is due to arrive next month. As well, the probe's main transmitter stopped working, so scientists now depend on a backup.

Also, a large solar flare a year-and-a-half ago damaged its power system.

Nozomi isn't dead yet. On Friday the Japanese Space Agency had this to say:

"Nozomi right now is under 'the last challenge' to repair its malfunction on which must be concentrated all [the] task force of scientists and engineers of Nozomi mission team until its outcome is clearly known. Upon recovering from the damage, we will then work on putting the probe to orbit around Mars and resume its exploration."

But if they can't repair the damage they will steer away from Mars. "Nozomi will, after once approaching Mars, escape from Martian gravitational sphere to become an artificial planet going around the orbit of the sun forever."