Rivals from the US and Europe get the bigger headlines and bigger budgets, but a little-noticed Japanese mission to a distant space rock may scoop them all.
Launched to the world's near-total indifference in May two years ago, the little probe Hayabusa (Falcon) is now on the brink of rendezvousing with a 630m asteroid on a mission that could prove historic.
If all goes well, Hayabusa will be the first spacecraft to bring home raw material from an asteroid, part of the primeval rubble left over from the making of the Solar System.
"It is an utterly remarkable project which has been given little coverage in the media," Patrick Michel, a French astrophysicist involved in the mission, said on Monday at a meeting of astronomers. "Understanding the chemical composition of asteroids will help us to understand how the planets were made. But the only asteroids we see on Earth are as scorched remains, as meteorites, not the raw substance itself."
Hayabusa, driven by an ion engine, a slow-but-steady form of propulsion which leaves maximum volume for scientific instruments, is now just 750km from the asteroid Itokawa, the mission Web site of the Japanese Aerospace Exploration Agency, said on Monday.
In November comes the white-knuckle part of the mission, said Michel, who works at the Cote d'Azur Observatory in southern France and with the French National Center for Space Research.
The craft will gingerly maneuver itself to within a few meters of the asteroid and then fire a projectile weighing about 5g into the surface at a speed of around 1,800kph.
If the arithmetic is right, and luck is on its side, material will be kicked out of the asteroid and some of it will shoot up a slender funnel.
The pellets are scheduled to be shot at three different sites in the asteroid, with each tiny sample being carefully stowed away onboard.
The spacecraft will also deploy a little robot, about the size of a large beer can, called Minerva, which for a couple of days will "hop" around the asteroid's surface, taking pictures and measuring the temperature.
Then it will be time to head for home. In June 2007, Hayabusa's precious payload, of just 100mg, should land in the Australian outback.
The US and the European Space Agency (ESA) have deployed huge resources on media-friendly missions to analyze comets and other primitive phenomena.
They include ESA's Rosetta, a US$1.2 billion mission, due to climax in 2014, to deploy a robot lab on a comet and analyze its soil and transmit the data back home.
In its Deep Impact mission, the US fired a metal projectile into a comet last July, using remote sensors to analyze the gas and dust spewed out by the impact.
Another US craft, Stardust, is due to return next year with material scooped by flying through the wake of a comet.
And it sent a spacecraft, Genesis, to capture samples of the solar wind. The craft crashed into the Utah desert in September last year, but some of its samples were saved.
"I'm going to be thrilled if the Japanese do this. I wish them all of the luck in the world," Carey Lisse, a senior scientist at Johns Hopkins University in Maryland and a member of the Deep Impact science team. "With all these missions, we're going to have a revolution in our understanding of these first bodies that formed the Solar System."