MOSCOW, Idaho – Seventeen years of work by a University of Idaho professor reached a critical milestone Friday when a probe from a spacecraft studying Saturn began its descent to the surface of one of the planet’s moons.
David Atkinson, an electrical engineering professor, has worked since 1987 on experiments carried aloft by the unmanned Cassini spacecraft studying the atmosphere of Titan, Saturn’s most mysterious moon.
On Christmas Eve, Atkinson received word that the probe with his experiment on board had detached itself from Cassini and had started its three-week descent.
The probe, called Huygens after the Dutch astronomer who discovered Titan in 1655, will study the ball of rock, ice and gas along the way. Scientists hope the 3-foot-wide, $700 million probe will survive its impact with the surface on Jan. 14.
“We’ve got 21 more days to hold our breath again,” said Atkinson. “But for now, I’m just feeling good.”
Launched in 1997, Cassini has been sending pictures and data from Saturn, the ringed planet almost 900 million miles from Earth, since last summer. Now, Atkinson and the other 200 scientists who have worked on the mission will have the chance to look even closer.
Titan was chosen because it is the only moon in the solar system known to have an atmosphere. Many believe it is representative of Earth at an early age.
Of the six experiments on board Huygens, four, including Atkinson’s, will study the moon’s thick orange atmosphere. As the probe descends, Atkinson’s Doppler wind-measurement experiment will chart the speed and direction of Titan’s winds. Other experiments will sample the atmosphere’s composition and will take pictures.
The orange haze is the reason so little is known about Titan. Atkinson said various theories speculate that Titan’s surface could be ice or liquid methane.
“Nobody really knows,” he said.
Telescopes sensitive to the near infrared spectrum can see the surface. “But we just don’t know what we’re looking at,” Atkinson said.
Another package of experiments, the “surface science package,” will study the composition of the surface.
If Huygens survives impact, that is.
There are no guarantees of success.
A European lander named Beagle 2 destined for Mars disappeared without a trace almost exactly a year ago after its separation from the Mars Express orbiter.
The hope for Huygens is that it will splash down in liquid since it is not designed for a hard-surface landing.
Most scientists think the internationally built probe will survive because its parachutes will slow it to only 5 meters per second at landing. That would reduce the impact to the equivalent of a normal-sized person jumping off a 4-foot-high wall, Atkinson said.
The data the probe should yield is expected to multiply the knowledge of Titan many times over and provide scientists with a peek at Earth’s past.
Space travel is the only way to make such discoveries, Atkinson said.
“I think of Titan and the planets as a laboratory for studying the Earth,” he said.
Atkinson’s next big project is a mission to Neptune and its moons. It is likely some of his students will be able to work on that flight because it won’t arrive for at least 30 years.
“These missions outlive us,” Atkinson said, noting the idea for the Cassini mission was hatched in the late 1970s. Atkinson is 49 years old now, and his first son was only 2 when Atkinson joined the mission.
“Now, he’s 19 years old,” Atkinson said. “My other two children are 16 and 13. They weren’t even here when this started.”