A spacecraft on a mission to ex-planet Pluto has experienced a computer malfunction just a few days before reaching its destination.
The New Horizons probe, operated by Nasa, lost communication with ground control on Saturday. The space agency said the spacecraft continued flying on an autopilot for the duration of the outage and promptly switched from the main to the backup computer.
Nasa said a "hard-to-detect timing flaw in the command sequence" that occurred during preparations for the flyby scheduled for 14 July caused the incident and that no similar procedure was planned for the remainder of the journey ahead of the encounter.
“I’m pleased that our mission team quickly identified the problem and assured the health of the spacecraft,” said Jim Green, Nasa’s director of planetary science. “Now – with Pluto in our sights – we’re on the verge of returning to normal operations and going for the gold.”
It took controllers at the Applied Physics Laboratory of John Hopkins University about an hour and twenty minutes to re-establish contact on Saturday afternoon. At this point, the spacecraft was flying in a safe mode. Its backup systems initiated a data transmission process to help engineers diagnose the problem.
Due to the vast distance between Pluto and the Earth, the signal from New Horizons travels four and a half hours before reaching the ground control. It thus requires a nine-hour round-trip to complete the communication circle.
The engineers concluded no hardware or software fault occurred and the spacecraft is expected to return to normal operations on Tuesday.
According to the mission’s principal investigator, Alan Stern, the incident won’t affect the spacecraft’s primary objectives and may have limited implications for secondary objectives.
“In terms of science, it won’t change an A-plus even into an A,” said Stern, of the Southwest Research Institute, Boulder.
New Horizons, launched in 2006, will pass within 12,500km of Pluto and collect information about its atmosphere, moons and magnetosphere. It will also collect data on other objects in the Kuiper belt, a distant region of the Solar System beyond the orbit of Neptun.
The spacecraft has been taking images of Pluto since January this year.