Farmer: Patience a necessity in scientific exploration

A little less than one year from today, NASA's Mercury Surface, Space Environment, Geochemistry and Ranging space probe, MESSENGER, is scheduled to settle into orbit around the planet Mercury. Getting there has required careful planning, teamwork and an awful lot of patience.

Most of NASA's missions have focused outward, away from our sun. The 1970s Viking missions, and more recently, the exploration rovers and the Phoenix sampler, have all sought to explore Mars, our next-nearest neighbor in the solar system. Both Martian rovers, Spirit and Opportunity, have been working hard since January 2004. While the rover Spirit appears to be permanently disabled, both now are resting, trying to get through another tough winter on the chilly plains of Mars where they have far exceeded their 90-day missions.

The deep-space probe missions of the 1970s have looked even farther out. Launched more than 30 years ago, the Voyager spacecraft visited the outer planets Jupiter, Saturn and Neptune. Having passed the outer edge of our solar system, they now are the most distant manmade objects in the universe. Both continue periodically to phone home and inform us about the outer limits.

But getting MESSENGER to Mercury has presented a different sort of challenge. In order to escape Earth's gravitational tug, the spacecraft had to be accelerated quickly aboard a Delta II rocket. The next thing it had to do was slow down - way down. The gravitational pull of the sun is so great on a tiny spacecraft that if it misses its target, it will get pulled toward the sun and never be heard from again. To slow down, MESSENGER has had to complete a number of "fly-bys" of Mercury in which it loses a little bit of its momentum each time - a trick known as gravitational braking. For nearly six years, MESSENGER has been patiently flying toward this goal.

If all goes according to plan, a year from now, MESSENGER will finish its journey and settle into orbit around the planet closest to the sun. It will begin sending back a wealth of information about Mercury's surface, atmosphere and perhaps even what lies deep in her core. But MESSENGER's journey began long befor