IT TOOK NINE YEARS for NASA's New Horizons spacecraft to travel the 3 billion miles to Pluto, but that's just a fraction of the time researchers like Ivan Linscott had invested in the mission.
The Stanford astronomer, a principal investigator for the program's Radio Science Experiment (REX), started work in the late '80s on the methodology used by the radio science receiver/radiometer, one of seven instruments in the spacecraft's payload. And he had been part of the New Horizons project since its inception 14 years ago.
The payoff came down to a few tense moments this summer, as New Horizons closed in on humanity's first close look at the dwarf planet. Linscott spent the night of July 13 in nervous vigil at the Mission Operations Center in Laurel, Md., monitoring the radio waves beaming towards the spacecraft from NASA's Deep Space Network in Australia and California.
Then came the wait for the reply. If all went to plan, REX would pick up and record NASA's radio waves as the spacecraft passed behind Pluto at 30,000 mph, gleaning data about the orb's atmospheric temperature, pressure and composition. (The average molecular weight and temperature of the icy rock's atmospheric gases could be determined by their effect on the path of the radio waves.) This was the first time a space mission's radio science experiment was using a signal from Earth rather than one from the spacecraft; only a ground-based antenna would give a signal strong enough to cover the spacecraft's vast distance from Earth and speed.
But the many successful rehearsals during New Horizons' long voyage could still have been rendered instantly meaningless by a collision with a speck of space dust, not to mention by technical mishaps. It was only when Mission Control reported "signal lock," meaning New Horizons data was being received and decoded, that the celebrations began.
Illustrations: NASA."I was unable to speak for a while," Linscott says. "My throat was choked."
REX was developed in partnership with Johns Hopkins University under the direction of Len Tyler, MS '65, PhD '67, a Stanford electrical engineering professor who was a principal investigator on the project before his retirement, and Linscott. They were supported by a small army of Stanford scientists and grad students who perfected REX—a pair of circuit boards each weighing just 3.5 ounces.
For all that work, the encounter with Pluto lasted just four hours. Linscott likens the event to Thanksgiving dinner—lots of preparations for something that passes before you know it. Still, it will take a year to fully digest this meal. New Horizons sends data at a rate that makes dial-up modems look swift.
And dessert may be yet to come. With the spacecraft in good shape, Linscott is hoping for an extended mission for REX to further explore the Kuiper Belt, home to comets and other dwarf planets orbiting in the solar system's frigid extremities.
