NASA says scientists are planning to return the New Horizons probe to normal science operations on Tuesday, a week before its historic Pluto flyby, after figuring out what caused a weekend glitch that briefly knocked it out of contact with Earth.
"I'm pleased that our mission team quickly identified the problem and assured the health of the spacecraft,” Jim Green, NASA’s director of planetary science, said Sunday in a mission update. “Now — with Pluto in our sights — we’re on the verge of returning to normal operations and going for the gold."
The New Horizons team traced Saturday's failure to a hard-to detect timing flaw in a spacecraft command sequence that occurred during operations to prepare for the July 14 flyby, NASA said. Because of the flaw, the spacecraft went out of communication for almost an hour and a half, switched control from its primary to its backup computer and came back online in protective safe mode.
The piano-sized spacecraft let engineers know that it was healthy and capable of receiving commands. Over the day that followed, New Horizons team members went through a troubleshooting routine to track down the glitch.
Now they're gradually bringing the spacecraft back to normal — but the task requires a few days in part because New Horizons is almost 3 billion miles (5 billion kilometers) away. It takes four and a half hours for signals to reach the probe at the speed of light, and another four and a half hours to receive the spacecraft's response.
The operation that triggered the flaw won't happen again, NASA said. New Horizons is currently about 6 million miles (9.9 million kilometers) from Pluto and is traveling on course for its flyby at a speed of more than 30,000 mph (50,000 kilometers per hour). NASA said the outage shouldn't have any impact on the $728 million mission's ability to meet its primary objectives.
"In terms of science, it won't change an A-plus even into an A," the mission's principal investigator, Alan Stern of the Southwest Research Institute, said in Sunday's update.
New Horizons was launched more than nine years ago with the objective of studying Pluto and its moons. The instruments aboard the spacecraft will map the dwarf planet's surface, gather data about its composition, sniff its thin nitrogen-rich atmosphere and taste the dust surrounding it.
Among the mysteries that have come to light already are a series of dark spots around Pluto's midsection, sometimes referred to as "train track terrain"; and a dark circle around one of the poles of Charon, Pluto's biggest moon.
After the flyby, New Horizons is expected to send data back to Earth over the span of 16 months or so. The team is already drawing up plans for another flyby of an object farther out in the Kuiper Belt, the broad ring of icy material beyond the orbit of Neptune.